Ladies and gentlemen, before I start my technical talk I want to welcome all of you to this congress in Taejon. It is a great pleasance to meet old friends and colleagues, in Korea. The high speed photography technology in Korea is now resonably matured in the last 15 years of time, the experimental technique has been innovated, and it has acquired elaboration and exploration as the speed of the phenomenon is getting faster and the applications are diversified. There are many applications of the m-sec high speed technique in the industries. In these cases although the speed is slow, usefulness of the image obtained is tremendous. p -sec high speed photography is applied in the usual ballistic and explosion researches and combustion researches of heat engines and jet engines. The applications of high speed laser pulse(n-sec, p-sec, and f-see) are made in chemical kinetics researches and laser plasma researches. We do not have many dedicated manufacturing industry for high speed photography instruments. The high speed cameras are in many cases imported from abroad, however, there is one efficient and active industry of medium size which is covering a major portion of the high speed framing and streak camera market in Korea.

This paper gives a brief survey on some new progress on high speed photography and photonics in China since 1988. It's history and organization and the status before 1988 had been reviewed by professor Wang Daheng at 18th ICHSPP held in 1988.

The straightness of the jet is the most challenging problem in shaped charge technology. Hence, the deviation of the jet from the symmetry axis originating from the collapse zone and, additionally, the dispersion velocities generated during the particulation processes are of crucial interest. In order to measure these quantities, one must look perpendicularly to the jet in at least two distances from the jet origin. To achieve this in an expedient and economic way, the author has developed a new electrically driven streak camera. At a writing speed of 1 mm/microsecond(s) the recording time is about 100 microsecond(s) . Such a long continuous recording time is needed to observe the jet as it passes at longer standoffs, and to obtain a highly accurate measurement of the jet straightness in two dimensions. The camera can also be applied in analyzing the 'normal' jet characteristics such as jet velocity distribution, accumulated jet length, accumulated particulization time, discrete particulation times, discrete particulation distances, jet diameter, jet surface characterization etc. By using as many commercially available components as possible the costs can be kept relatively low. By using the coincidence of the slit/slit position a build-in-shutter of 1 ms minimum exposure time is integrated in the camera.

To meet the needs of engineers and scientists of the 1990s, Hadland Photonics have developed a new concept high speed camera capable of framing rates up to 100,000,000 pictures per second as standard. Recent surveys have conclusively shown that better image quality than that offered by current image converter cameras is a criteria foremost in the minds of those who use high speed imaging as part of their recording instrumentation. To this end, the Imacon 468 has been developed offering a high resolution camera with virtually zero distortion and intensity variation across the total picture area. Variable interframe, exposure, gain and image manipulation are fully controlled by a PC making this camera compatible with modern trends of data recording. The unique optical system, designed specifically for this camera, allows a single viewpoint for the multiple intensified CCD image sensors. Comprehensive software for controlling the camera, data transfer, and image processing is available for IBM P.C. compatible computers allowing finger tip access to experimental parameters.

Air bubbles are observed at the moment of there emergence from a vertical nozzle in water. We can classify them into two types by formation process. The bubbles broken off from a large air bulk always emit sound pulses, but those not being split but keeping their initial volume hardly produce any sound. By comparing their motions and distortions not only by means of the sequential series of photographs but also by the streak photographs of the vertical linear portion of the axisymmetric bubble, we obtain the difference of the subtle distortion of their surface which causes the emission of sound pulse.

A new high repetition shutter camera with the unique framing tube has been studied. The shutter time of 580 ps and dynamic spatial resolution better than 400 TVL have been experimentally obtained at the repetition shutter rate of 1 MHz. Also, ultra short shutter time of 34 ps has been obtained at the repetition shutter rate of 10 KHz.

Design of universal camera operating in streak and four-, six-, and eightframe modes is reported; the camera is intended for recording high speed phenomena in ultra violet and hard X-rays with limiting temporal resolution of 2 X 10^-10 s and 5 X 10^-9 s for streak and frame modes, respectively.

1. The streak camera for observation and measuring of characteristics of picosecond and nanosecond radiation processes with single photoelectron count mode was created. 2. The streak camera, in couple with calibrating systems of its characteristics and high-level software, may be applied both as experimental and standartifying units for ultra short optical signals.

Modules of three types based on single-camera ICT with magnification 1, 0.6 and 0.3 are described which operate in regimes of supplying ICTs with dc and pulsed voltage. The modules are intended for image intensification.

A possibility of temporal analysis of picosecond light pulses in the IR region with the help of photocathodes based on semiconductor superlattices (SL) of type I (InP/InGaAs) with Schottky barrier is discussed. A new principle of avalanche photoelectron emission from such an SL at interband absorption of light is suggested. The principle is based on the electrons free length path increasing in a SL with narrow quantum wells under high electric field applied to the SL. The idea makes it possible to develop a new device - avalanche photocathode with internal amplification for the IR region of 0.9-2 micrometers and temporal resolution better than 30 ps. It is proposed to use doped as well as undoped SL as basis for photocathodes sensitive to the IR radiation in the range of up to 10 micrometers . The photoemission from such structures is caused by the intersubband absorption of light in quantum wells. The use of undoped SL greatly reduced the thermoemission current of the photocathode but requires additional excitation of the SL by light pulses with energy approximately corresponding to the band gap of the narrow band gap material of the SL. The temporal resolution of such photocathodes is supposed to be less than 30 ps. The conditions for the avalanche photoelectron emission obtaining are determined, and the SL parameters which meet the requirement of maximum quantum efficiency of the photocathode are calculated.

The properties of IR photocathodes intended for streak tubes as well as InGaAs/InP heterostructures were investigated. It has been shown that optical transmittance, photoluminicence, photovoltaic and C-V measurements made possible to control the heterostructure composition with the precision better than 1% and to determine its type of conductivity and carriers concentration. Since these techniques are nondestructive ones and they do not require any electric contacts deposited onto the structure they could be used for controlling of the grown heterostructures. The properties of InGaAs/InP heterostructures with Schottky barriers were studied by scanning electron microscope (SEM) working in electron beam induced current (EBIC) mode. It has been shown that for the investigated photocathodes the photoemission current value strongly depends on the applied anode voltage, and therefore at high electric field 10⁴ V/cm the photoemission quantum efficiency is substantially increased. Preliminary study of the photoemission current stability were carried out for a sealed volume serving as a model of a streak tube.

An advanced modification of a picosecond frame tube with an additional electrostatic lens allowing to equate the sensitivity of deflection plates is described. A formula to determine a focal distance of the additional lens is given.

A specialized camera based on a low noise ICT without the image sweep is described; it allows to record by a CCD TV-camera a series of frames with comparatively high frequency due to ICT strobing and short persistence of its screen.

For providing time-, space- and intensity- information of pulsed radiation sources, several new techniques of fast-gated imaging systems have been developed: nanosecond gated proximity-focused MCP intensifiers, CCD solid-state cameras, image recording digitally systems and image processors. Gated MCPI are designed to provide large gain (10³-10⁴), fast optical shutter (< 1 ns), low shading (< 10%), high spatial resolution (10 lp/mm). CCD are used for the imager in the solid-state cameras. The cameras are designed to achieve a large dynamic range (-200:1), small frame time (1.0-3.0 ms), and high stability. Digitized image recording and new image processing made it possible to process images a local.

This paper discusses the characterization of a cylindrical microwave resonant cavity used as a deflection system of convert tube. In the cavity two TM₁₁₀ mode fields vertical to each other are excited and the electron beam is deflected by their magnetic field. Unlike usual deflection system of convert tube in which electron beam is deflected by electric field, this system has some special characters. Calculation shows this system introduces less spatial and temporal aberration, with almost no effect on the image quality, and the scanning speed can be very high. Also confining the field in a cavity, this deflection system has no edge field, which should be considered in metal plate systems. This system can be used in a circle-scan time analyzer and synchroscanner, or more in frame tube under some conditions.

Multiframe images at a meander shape microstripline were gated sequentially by a single high voltage pulse. The meander microstripline was made by a fine mesh contacting the input surface of the MCP and the coated rear face of the MCP to reduce the ohmic losses. The dynamic gain characteristics of the MCP gated by picosecond pulse were simulated by Monte-Carlo method taking into account the effect of electron transit time dispersion. The measured spatial resolution of the framing camera is 20 lp/mm and exposure time is approximately equals 100 ps.

In this paper a universal streak camera will be introduced. This camera consists of time distortion-compensated optical lens, vacuum ultraviolet-sensitive streak image tube, multifunction sweep circuits and CCD real-time readout system. It can work in 3 modes, including single shot, synchroscan and dual scan. This camera can also work in circular scan mode. The temporal resolution of 1.2 ps can be achieved in single shot mode. The operation frequency can be 82 MHz, 164 MHz, 200 MHz and 300 MHz for synchroscan and circularscan modes. In this case, the temporal resolution is operation frequency dependent, usually in the range of 1-3 ps. In dual scan operation mode, one deflector is driven by sine wave circuit, another by a slow ramp circuit. The scan speed along the fast and slow axis is 5 cm/ns and 26 cm/microsecond(s) -2 cm/microsecond(s) .

It is shown in this paper that if two microchannel plates are used in chevron configuration and are gated one by one by ultrashort electric pulses, the exposure time can be reduced considerably compare to that of one MCP due to the superposition of the gain narrowing effects of the two stages gating. Another advantage of this method is that the signal to noise ratio can be improved because of the increase of gain and reduction of hard X-ray induced background.

Triggering of instrumentation devices is crucial for successful recordings of high speed events, e.g. in experimental work on terminal ballistics and explosives. In harsh electromagnetic environments,, where reliable triggering may become a problem, opto fiber transmission links are attractive alternatives. Plastic fiber opto link components are, in our experience, very easy to use not only for signal transmission but also for detection of different experimental events. This paper describes simple, yet reliable, methods which have been used with flash radiography systems and an Imacon model 790 high speed camera.

The Prototype of Image Converter Streak Camera as single shot mode was developed by the joint research project between V TEK/Yonsei Univ. in Korea and GPI in Russia. The sweeping speed over (phi) 25 mm output screen area is selectable from 1 ns to 500 ns and the time resolution is better than 10 ps. This paper is showing the characteristics of streak camera and its simple applications.

High speed single frame camera using proximity focused MCP was designed and manufactured by V TEK with help of Yonsei University. The gating time of this camera is adjusted by specially designed control board and S/W easily and this camera has high repetition rate up to 250 KHz. In this paper, we are introducing the newly designed Single Frame Camera and its applications.

Two algorithms for determining of ICT time instrumental function are proposed that are applicable for the optical and IR regions of recorded radiation at different modes of operation. A program based on the algorithms is described. Examples of calculations are presented, on the basis of which the ICT mode of operation with the best temporal resolution has been chosen.

Experimental and calculated determination of temporal resolution of soft X-ray streak camera 'Agat-VUF' is described. The ways of improvement of temporal resolution are discussed.

A camera based on MCP-ICT with image rotation is described; it allows to get single frames of 2 X 10^-7 to 5 X 10^-3 s duration in a single triggering mode or with maximum frequency from 10 kHz to 100 Hz depending on frame duration.

A unit designed to control a planar ICT with a single MCP is described. The main parameters of the unit are given, some questions related to its circuit engineering are considered briefly, the test results are reported.

Within the framevork of "one-event losses" theory the following formula is obtained for t -pulse radiation response aD) Jr Q rrt ,C p LA cos ix z xexp ( ' c ° ) u I on(t, L / Ucosf) G(#ii: I 0 out oc(OL/Ucsf) RadI at i on from the vacuum s i de ( "di rect" rad i at i on) corresponds z=i and " }( 4. cos I "; radi at i on from the other s i dc (,' ind i rect" rad iat ion) corresponds e arid "ç csa". Q - r'adiatiori pulse energy; m - defines the fraction of photoactive absorption; L - probability of absorption of radiation; p - probability of passing by the electron of the harrier at the vacuum boundar'y; u - photoelectron velocity in the conducting band; P - angle between normal to vacuum boundary and the elect1rori trajectory; K - probability of loss of energy by an electron required for emission per unite of distance; L thickness of photosensitive layer. When indirect radiation the time resolution corresponds to and according to our estimation (for When direct radiation the time resolution is equal T0T -14accord 1 ng to our est imat i on T0 (0.6 ÷ 3)xlO at contrast 0. (for = i.O6pim). For determine T one must take into account photocurrent fluctuations arid Coulomb's interaction.

The technique features and main structure of Model DPG Continuous Access High Speed Rotation Mirror Streak Camera are presented and its application examples introduced in detonation experiments.

High-speed photographic recording as one of the most effective methods for studying high-speed processes, is used in solving contemprorary scientific and technological problems, thus facilitating engineering progress. High-speed photography is widely used in plasmas studying when is ofvital concern in developing new sources of energy (for example, controlled thermonuclear reaction and magnetohydrodynamical methods of direct trasformation of energy) powerful light sources, lasers and studying aerodynamic and hydrodynamic processes. The problems of fuel combustion in engines and furnaces, which are of decisive significance for automobile turbines, metallurgical and chemical industries also use investigations with the help of high-speed photography. In this way, methods of high-speed photography and cinematography have became one of most important means of technological advancement. In Russia, the first information appeared in the middle of the XVIII century, when luminary Academician Michael Lomonosov and your colleague the famous physicist, Academician Georg Reichman used the rotating mirror for investigating into lightning. In the second half of XIX century director of the Pulkov observatory Academician Struve, at the saue time as Physo, used the method of the modulate light by means of rotating a wheel for determiniting light velocity. Later the known Russian astrophysicist professor Belopolsky for the experimental testing of Dopler effect used that is known as the so-called optical acselerator (some rotating mirrors wich where instafixed on the wim of a wheel and magnified the velocity of light the beam movement and solved the problem. At the beginning of the XX century few methods of investigating high-speed processes where used to study burning and explosing by means of photochronographers by our outstanding scientists Academicians N.N. Semyenov and Ju.Chariton. Optical-mechanical systems for high-speed photography where widely used after the Second World War(1945) was constructed. In 1947 at the "Krasnodarsky plant" enterprise the first cinemacamera (SKS-1) with optical compensator. It was used up to now by a scientists. An extensive development of high-speed methods received recognition in the Institute of Chemical Physics the Academy Sciences of the USSR, under Leadership of Academicians N.N.Semyenov and M.A.Sadovsky and in the State Optical Institute headed by the Academician A.N. Terenin and professor E.N.Zarevsky. It began studies in the Field of methods and conctruction of devices for the recording and measuring spatial-time and power parameters of high-speed processes. Under the leadership of professor G.L. Shnirman and J.A.Cherny high-speed photochronographer and photocamera for measuring the velocity of the development, dimensions , the coloured and brightness temperatura and the distribution of the energy in the process under investigation wire constructed. The actual constructors were professor A.S. Dubovik and S.G.Grenidun and senior scientific worker P. V. Kevlisvily, G.P.Starcev and M.V.Leykin, leading engineers B.G.Belov, B.T. Vorobyev and l.a.Saburov. The important stage in the developing high-speed photography in Russia was constructed in 1948 (the Institute of Chemical Physics the USSR Academy Sciences) it was the universal hidh-speed photocamera and photochronograph SFR. By means of this instrument some thousands of impotent experements were carryed out in the various spheres of knowledge and tehnology. The centres of construction and production of hidh-speed devices are: the Institute Chemical Physics of the USSR Academy Sciences, the Earths physics of the USSR Academy Sciences, the Earths physics of the USSR Academy of Sciences, Industrial Enterprise "Krasnogorsky Plant" (Krasnogorsk) ,the Institute of fine mechanics and optics (St. Petersborg) , the Scientific-Industry Enterprise (SIE) , "Photopribor" (Cherkassy) , the Research Institute of optical-physical meansurements (RIOPhM) (Moscow) , the Moscow Construction Burean of cinema-apparatus (MCBCA) (Moscow). Like this optical-mechanical systems for high-speed photography and cinematography widely development in Russia and make it possible to solve scientific and technology problems.

The programmable electronic high-speed camera announced at the 20th ICHSPP has now been progressed to initial production stage and tested in several applications. The whole camera system consists of a camera body with a single interchangeable standard objective lens, an eight channel frame grabber integrated in an industrial computer, and eight channel light pulser (for backlight mode only), a programmable sequencer and a high-resolution SVGA monitor plus 1 to 8 video monitors for immediate frame observation. The camera operates in backlight as well as in frontlight mode providing a sequence of up to eight high resolution images. A framing rate of up to 1 million fps (frontlight) or 10 million fps (backlight) can be achieved. The system and some application results are described.

This paper describes a fully solid state high speed video recording system. Its principle of operation is based on the use of several independent CCD imagers and an array of liquid crystal light valves that control which imager receives the light from the subject. The imagers are exposed in rapid succession and are then read out sequentially at standard video rate into digital memory, generating a time-resolved sequence with as many frames as there are imagers. This design allows the use of inexpensive, consumer-grade camera modules and electronics. A microprocessor-based controller, designed to accept up to ten imagers, handles all phases of the recording: exposure timing, image digitization and storage, and sequential playback onto a standard video monitor. The system is capable of recording full screen black and white images with spatial resolution similar to that of standard television, at rates of about 10,000 images per second in pulsed illumination mode. We have designed and built two optical configurations for the imager multiplexing system. The first one involves permanently splitting the subject light into multiple channels and placing a liquid crystal shutter in front of each imager. A prototype with three CCD imagers and shutters based on this configuration has allowed successful three-image video recordings of phenomena such as the action of an air rifle pellet shattering a piece of glass, using a high-intensity pulsed light emitting diode as the light source. The second configuration is more light-efficient in that it routes the entire subject light to each individual imager in sequence by using the liquid crystal cells as selectable binary switches. Despite some operational limitations, this method offers a solution when the available light, if subdivided among all the imagers, would not allow a sufficiently short exposure time.

This paper presents a prototype digital still camera of which features are passive auto focus, effective memory control, JPEG image compression/decompression, image of storage of JFIF format, use of PCMCIA standard IC memory card, image display on LCD, data interchange with other multimedia systems.

A questionnaire was distributed to scientists and engineers all over Japan to compile information on conventional and potential application of high-speed videography and special conditions associated with using them in practice. The distribution of the required frame rate shows that existing high-speed videocameras of 10³ to 10⁴ pps cover only 30-40% of the potential usages, while existing image-converter multiframing cameras of 10⁶ to 10⁷ pps cover more than 90%. It is, however, clear from the authors' experiences that dynamic recognition, which is supported by videocameras but not by multiframing cameras, is an essential and very powerful tool in scientific and engineering research. New concepts to produce high-speed videocameras of 10⁵ to 10⁷ pps are therefore presented.

This paper treats principles of design of a readout device with CCD matrix for a high definition spectrometer. The device allows getting 512 counts in dispersion direction, has the dynamic range of 10³ at threshold illumination of 10^-3 lx.

Automatic measuring of image information recorded on high-speed 35 mm photography film is realized by a measuring system with adoption of 2D Charge Coupled Device (CCD) array as an image sensor and in connection with optics, precision mechanics, electronics, image processing and computer technology. The pixel numbers of CCD image sensor are 1300 X 1000, the pixel size is 6.8 micrometers X 6.8 micrometers and the pixel resolution is 19 micrometers . The system also has semiautomatic reading mode. The automatic and semiautomatic mode can be interchanged. The measuring accuracy of 2D coordinates is within 15 micrometers and the measuring speed is 2 f/s approximately equals 3 f/s.

This paper describes two complete fast imaging systems using a commercial Charge Coupled Device (CCD). It includes two different storage systems (analogical and digital) and describes a new high speed sensor built as an Application Specific Integrated Circuit (ASIC) in Complementary Metal Oxide Semiconductor (CMOS) 1.2 micrometers technology. The first system has been applied to a biological research.

In this paper, we propose the architecture of the sensor of a snapshot video which allows to store the set of images from a sequence of snapshots. We describe the elementary cell which associates the photosensitive element to the memory zones. We present the circuit with which we are characterize the photoelements, and we present the charge transfer study circuit.

This article describes a method that allows the digital recording of sequences of three black and white images at rates of several thousand frames per second using a system consisting of an ordinary CCD camcorder, three flash units with color filters, a PC-based frame grabber board and some additional electronics. The maximum framing rate is determined by the duration of the flashtube emission, and for common photographic flash units lasting about 20 microsecond(s) it can exceed 10,000 frames per second in actual use. The subject under study is strobe- illuminated using a red, a green and a blue flash unit controlled by a special sequencer, and the three images are captured by a color CCD camera on a single video field. Color is used as the distinguishing parameter that allows the overlaid exposures to be resolved. The video output for that particular field will contain three individual scenes, one for each primary color component, which potentially can be resolved with no crosstalk between them. The output is electronically decoded into the primary color channels, frame grabbed and stored into digital memory, yielding three time-resolved images of the subject. A synchronization pulse provided by the flash sequencer triggers the frame grabbing so that the correct video field is acquired. A scheme involving the use of videotape as intermediate storage allows the frame grabbing to be performed using a monochrome video digitizer. Ideally each flash- illuminated scene would be confined to one color channel, but in practice various factors, both optical and electronic, affect color separation. Correction equations have been derived that counteract these effects in the digitized images and minimize 'ghosting' between frames. Once the appropriate coefficients have been established through a calibration procedure that needs to be performed only once for a given configuration of the equipment, the correction process is carried out transparently in software every time a sequence is acquired.

High speed photographic systems like the image rotation camera, the Cranz Schardin camera and the drum camera are typically used for recording and visualization of dynamic events in stress analysis, fluid mechanics, etc. All these systems are fairly expensive and generally not simple to use. Furthermore they are all based on photographic film recording systems requiring time consuming and tedious wet processing of the films. Currently digital cameras are replacing to certain extent the conventional cameras for static experiments. Recently, there is lot of interest in developing and modifying CCD architectures and recording arrangements for dynamic scene analysis. Herein we report the use of a CCD camera operating in the Time Delay and Integration (TDI) mode for digitally recording dynamic scenes. Applications in solid as well as fluid impact problems are presented.

A videography system is introduced and its ability in catching image of high speed projectile is shown. This microcomputer-based system consists of two optical gates, a CCD camera, a frame grabber, a flash lamp and some ancillary electronics. The optical gates are accompanied with some electronic circuits to provide accurate timing for image catching, and the frame grabber provides real time process capability for image processing.

When a high speed train enters a long tunnel, compression waves which were generated in front of the high speed train, coalesce into a weak shock wave and the shock wave eventually is emitted from the tunnel exit as a sonic boom. In order to investigate the tunnel sonic boom a 1/300 scaled tunnel simulator was constructed in which a plastic cylinder slides down along a 8 degree(s) inclined long tube with a speed of 60 to 110 m/s. The high speed cylinder and the steel tube represent the train and the tunnel, respectively. Double exposure holographic interferometric flow visualization was used for clarifying the formation and propagation of weak shock waves in the scale tunnel simulator. For interpretation of behaviors of weak shock waves, a shock tube experiment was also carried out again by using holographic interferometry.

this paper describes the experimental study of shockwave propagation conducted in high-speed real-time holographic interferometry and dual- reference-beam pulsed laser holographic interferometry. In these experiments, three kinds of holographic interferometers were used for visualizing and recording of the propagation of shockwave; a real-time holographic interferometer with high-speed framing camera, a real-time holographic interferometer with high-speed streak camera and a double pulsed ruby laser holographic interferometer with dual-reference-beam module. The holographic fringe patterns obtained from the first two interferometers could be used for qualitative analysis. However, the fringe patterns from the pulsed holographic interferometer could be processed digitally by phase stepping during reconstruction and the processed phase map demonstrated the possibility of quantitative analysis of high-speed flow phenomena.

A speckle-photographic method with a diffraction grating is proposed for improving the sensitivity of out-of-plane displacement measurement. This technique is based on the fact that the speckle displacement due to out- of-plane object displacement increases in the higher-order diffracted field.

A real time interferometric autocorrelator was fabricated for characterizing the pulse width and the phase distribution of ultrashort laser pulses. A data acquisition system based on the direct memory access (DMA) was devised in order to monitor the real time autocorelation trace. The system is capable of measuring not only the intensity distribution but also the phase distribution of optical pulses. The output pulses of a femtosecond Ti:sapphire laser were analyzed utilizing the system. Applications were made to demonstrate the characterization of the nonlinear optical processes in KDP and (beta) - BBO crystals. In a (beta) -BBO crystal, the phase mismatch effect was successfully identified and measured in the second harmonic generation (SHG) processes.

Interactions of a shock wave with a gas bubble were visualized by double exposure holographic interferometry or shadowgraph for four combinations of liquid/gas which are silicone-oil (1.0 cSt)/air, silicone-oil (10 cSt)/air, water/air, and water/helium. The gas bubble was exposed to a spherical shock wave generated by detonation of a microexplosive. The gas bubble contracted by hitting of the shock, and a liquid jet formed, as the case may be. Eventually, one or plural rebound shock waves occurred. It was found that there are at least three types of the rebound shock. The generation of it for each type is explained by sequential flow visualizations.

For continuous recording of interior acceleration process of high-speed projectile in a gas gun, a new method using inline hologram of a slender wire is proposed and demonstrated. The hologram pattern is recorded by a streak camera via a mirror, which is moving between the wire and the recording plane. The mirror is glued onto the nose of an accelerating projectile. Fringe spacings of the pattern depend only on distance Z between the wire and the recording plane for a fixed wavelength of a laser light source. The acceleration process, therefore, can be obtained precisely by analyzing the fringe spacings which gradually narrow with decreasing the distance Z due to the projectile motion. It was found that (1) the acceleration time of the projectile is about 14.1 ms, (2) the acceleration is almost constant except in the early stage, and (3) two kinds of oscillatory behavior of the projectile during the acceleration are recorded simultaneously.

To visualize the 3D motion history of a particle, an analysis method has been developed for streak holography. The method is based on the fact that inline hologram of a particle has circular fringe pattern that can be calculated either Mie scattering theory, or Fraunhofer or Fresnel diffraction theory. Generalized formulation of the analysis method has been made under the assumption of circular fringe patterns followed by giving various fomulae for the case of Fraunhofer approximation. The image analysis can be further simplified at discrete times when one of the fringes is just tangent to the camera slit. This method is successfully applied to one of particle streak hologram to obtain 3D trajectory of it. The results of these examinations suggest the feasibility of streak holography for the visualization of particle field such as aerosol transport, combustion, multiphase flow, etc.

Rain water polluted with natural and industrial contaminants, more commonly known as acid rain, has been used as an electrolyte to account for its effect on the flashover phenomenon across high voltage outdoor insulators. Optical and electrical techniques using high speed Schlieren photography and current measurement with LED were employed. The propagation of an impulse breakdown was then studied by varying the voltage waveforms. Experiments were also conducted with artificial acid rainwater of low pH value to determine the factor of safety over the actual rainwater characteristics. It was found in the present conditions, that given the same conductivity (sigma) neither the dissolved components nor the pH value of the rainwater influence significantly the discharge growth, while a substantial decrease of the propagation speed was measured with the increase of the front duration of the applied voltage.

In the process of tempering glass plates, high pressure air jets were impinged on heated glass plates and became supersonic ones for quenching and pressing efficiently the glass plates. Holographic interferometric flow visualization has been carried out in order to interpret the effect of supersonic flows and shock waves on the process of manufacturing the tempered glass plates.

This paper describes a new optical method, the high speed Moire topography of the shadow, to measure the yaw angle of a free-flight projectile, in which, the equipment can be simplified, for it needs only one camera, but the older ones need at least two. The formula of the calculation are deduced and the errors are analyzed. The final experimental results of a free-flight projectile by the new method mentioned above show that the yaw angle of a free-flight projectile can be measured accurately with the dynamic Moire topography of the surface of the projectile. This new method is available.

Laser Doppler shift velocimetry operating in the fringe mode is widely used to record the velocity history of optically reflective solid objects. When the object is rapidly accelerated, the time resolution of the Fabry-Perot Interferometer (FPI)/streak camera system is frequently inadequate to unambiguously record the data. That is, there is a 'dead time' during which fringes form and expand without producing a resolvable record. To remedy this, we have developed a dual, parallel cavity FPI which produces two sets of fringes at the slit of the recording streak camera. The input mirror of the FPI is a conventional flat while the output mirror is stepped so there are two mirror spacings. The input light is divided by the respective areas of the stepped mirror to form two sets of fringes; a higher quality set of fringes 'A' is used to determine the velocity history while a second set of fringes 'B' is used as a 'referee' to determine the number of fringe jumps during the 'dead time'. Since the two sets of fringes are necessarily interleaved, there is a possibility of fringe overlap, i.e., fringes of set A can spatially overlap fringes of set B. To date, two dual FPI's have been successfully constructed and characterized. The theory of operation, details of construction, and the results are described.

A method is presented for simultaneous measurement of object shape and displacement by combining Light-in-Flight recording by holography with holographic interferometry. The technique makes it possible to use ultra-short pulses, picoseconds or shorter, to examine extremely rapid dynamic events. Theoretical and experimental results for fringe evaluation are presented. If a Light-in-Flight hologram is double exposed, and the object under study is displaced between the exposures, two images will overlap. If the deformations are in the order of micrometers, an ordinary interferogram is attained by letting an image processing system adding together the interference fringes seen for each contouring line, but with the additional advantage of information of the 3D shape. If the deformations are large compared to the wavelength and small compared to the coherencelength, the two images will partly overlap. The envelope of the intensity curve becomes broadened. This broadening is a measure of the displacement. If the deformations are large compared to both the wavelength and the coherencelength used, two separated contouring lines results, representing the two different object positions.

Heat transfer characteristics for natural convection in open cavity has been investigated by using the holographic interferometer. The diameter of test area exposed by interferometer was 130 mm. The study of open cavity was obtained with single flush-heated height 42.8 mm and width 58.8 mm. The vertical plate was uniformly heated and two horizontal surfaces were insulated. Experiment has been performed with changing of heat flux 5 W to 50 W from vertical plate. Experimental results are compared with the results of numerical code under same condition and the agreement is found to be good. Holographic interferometer was assumed to be an appropriate method of the study about heat transfer characteristics from the results.

The liquid fuel injected at a high injection pressure into the combustion chamber of a diesel engine undergoes atomization, evaporation, mixing with air and combustion. The quantitative measurements of these processes are essential to understand and control the combustion phenomena. This article summarizes recent work that has been performed by the author's group at Tokyo Institute of Technology in the field of 2D imaging diagnostics of diesel fuel sprays. The work was concentrated on enhancing the capabilities of quantitative measurement by 2D imaging techniques which use a pulsed laser sheet as the incident light source. Experiments were conducted applying these techniques to nonevaporating, evaporating, and combusting sprays achieved in the optically accessible chamber of a rapid compression machine. One of the most exciting outcomes is the 2D quantitative measurement of local dropsize distribution in a spray: The fluorescence and scattering intensities from droplets in a spray were imaged simultaneously and their ratio yielded a successful 2D particle sizing. Another application of the 2D imaging is the time and space resolved measurement of fuel vapor concentration in a transient spray. Selected 2D contour mappings of droplet size, fuel vapor concentration and soot concentration are presented.

The high spectral brightness and short pulse duration of tunable high power excimer lasers allows the 2D and 3D application of techniques like laser-induces fluorescence (LIF), Mie and Rayleigh scattering for high speed imaging in industrial applications. The construction of these lasers allows easy transportation and installation to perform measurements at industrial applications. The construction of these lasers allows easy transportation and installation to perform measurements at industrial facilities which can not be moved. In combination with suitable filters and gated image-intensified CCD cameras techniques are now available to measure multidimensional distributions of temperatures and concentrations. Simultaneous measurements of temperature fields and hydroxyl radical distributions were performed to study the influence of turbulence on large premixed natural gas flames. A combination of temperature and nitric oxide concentration measurements yielded information about the correlations between NO formation and burner design in domestic gas burners. Detailed experimental studies on the carbon dioxide-laser induced ignition of CH₃OH/O₂-mixtures in quartz reactor are performed to supply quantitative data for direct comparison with the numerical results of a mathematical model for ignition processes in 2D geometries. Temporally and spatially resolved measurements of flame position and OH concentration are presented for different conditions and compared directly to the computational results. LIF, Rayleigh and Mie scattering were used for measurements of temperature fields, fuel and OH radical distributions in engines. Finally a novel type of combustion control system for municipal waste incinerators using fast infrared thermography to obtain information about the temperature distribution in the furnace interior is described. A fast scanner camera operating in the mid infrared was installed which allows the direct imaging of the fuel bed through the overlying flame and flue gas atmosphere and rapid determination of temperature distribution.

Tunable ArF and KrF lasers are being used to produce species-, space-, and time-resolved images of complex gaseous media. These media may be analyzed for composition, density, temperature, or flow velocities with the observation of various laser induced light emissions. The techniques are, in general, highly selective, sensitive, and nonintrusive. We discuss methods that can yield an increase in signal, or that allow desired signals to be differentiated from interfering emissions, by the use of appropriately polarized lasers or by polarization analysis of emitted light.

The new imaging system developed in our laboratory facilitates the solutions of problems otherwise difficult to remedy. In this lecture, the progressive steps taken for building our new diagnostic tool are explained, followed by a description of the system and our data processing methods. Some of the results obtained by using the device are presented. The system design was directed to incorporation of off-the- shelf components with several newly fabricated units in order to overcome limitations in existing infrared (IR) imaging systems. In the new IR imaging system which recently became operational, four high-speed IR camera units are lined up to a single (reflective) optical unit having three spectral beam splitters. This permits simultaneous framing of four geometrically (pixel-to-pixel) identical images of the same object in respective spectral bands. The multispectral imaging by the camera is activated either by the internal clock (at a rate over 1,800 frames/sec) or an external signal such as pulses generated by an encoder. Unique features incorporated in the system include: independent variation of the framing rate and the exposure period in terms of time period (as short as 30 microsecond(s) ec) or the number of external pulses; control of the total number of images to be obtained per event from successive cyclic processes. The new device is applied to 'quantitative imaging' of rapidly reacting events/objects, e.g. determination of temporal and spatial variations of the thermochemical characteristics. Thermal objects, which typically involve a reactor wall and a gaseous mixture in front, are studied by obtaining the high-speed digital readout from the corresponding pixels of: two wall images in separate wavebands and two mixture images in other bands, i.e., total of four matrices of digital output at a time. The results are processed by the conventional two-color method and a new dual-band spectrometric algorithm.

The soot formation rate at high pressures has been studied with a premixed propane-oxygen-inert gas combustion in a specially designed disk-type constant-volume combustion chamber. Premixtures are simultaneously ignited by eight spark plugs located on the circumference of chamber at 45 degree intervals in order to observe the soot formation rate under high pressure. The eight flames being converged compress the end gases to a high pressure. The laser schlieren and direct flame photographs for observation field with 10 mm in diameter are taken to investigate the effects of curvature for the optical path in the flame front and gas flow in the measured position on soot formation rate. The soot formation rate in the chamber center during the final stage of combustion at the highest pressure is measured by the in situ laser extinction technique at the following conditions; 0.4 to 5.0 MPa for pressure, 1600 to 1900 K for temperature and 2.0 to 2.2 for equivalence ratio. The burnt gas temperature is measured by the two-color pyrometry method. The pressure and temperature during soot formation are changed by varying the initial charge pressure and the volume fraction of inert gas in the premixture, respectively. In the present study, it is found that the soot formation rate can be expressed by an empirical pseudo- first-order kinetics for surface growth even at high pressures, and that the rate constant of soot formation is only dependent of the temperature.

In order to establish the ignition system for lean burn, the influence of the number of spark plug, spark times and spark intervals on discharge pattern of spark energy, ignitability and combustion characteristics were evaluated. By visualizing the flame propagation with the number of spark plug, heat release was related with flame area, heat loss related with contact wall area by burned gas, combustion duration related with maximum flame travel distance respectively. It showed that, ignitability remarkably increases with the case of MSCDI than with the case of single spark and the lean limit extended fuel/air equivalence ratio by 0.1, the increase of magnitude and lasting time of capacity component and inductance component was multi spark discharge in a row.

Optically accessible D.I Diesel engine with a rectangular combustion chamber was constructed to visualize the behavior of sprays and flames in the combustion chamber with close conditions of pressure and temperature of actual engine. The behaviors of sprays and flames in the combustion chamber at compression stroke and expansion stroke in accordance with operating conditions were photographed with high speed camera by Back Illumination Scattering Method and Schlieren method. With photographs taken by these methods, behavior of evaporating sprays and spray droplets, ignition points, the flame propagation were observed and analyzed at a time- and space-dependent fashion with image processor.

New type nonlinear crystals are widely used materials for frequency doubling and parametric process to generate the ultrashort pulse over a large wavelength range. The angle phase-matching curves for optical parametric generation in three principal planes of biaxial crystal KTP pumped by 355 nm, 532 nm and 1064 nm ultrashort pulse light have been calculated and analyzed. The calculated results have been confirmed by experiment. Picosecond tunable parametric laser from 630 to 3420 nm was obtained with a 20 mm long KTP pumped by 532 nm in the X-Z plane via type II phase matching. The maximum energy conversion efficiency is 30%, pulse duration 40 ps, repetition rate 10 pps and maximum peak power of signal wave is more than 30 MW. Efficient second harmonic generation pumped by ultrashort pulsed parametric laser has been obtained from 427- 470 nm in KNbO₃ with 1.5 mm in length at room temperature. The energy conversion efficiency is over 40%. The peak power of 30 ps pulsed blue light is up to 60 KW.

A sealed-off and compact CuBr laser was used to be an image-brightness amplifier in high-speed photography and high-speed microphotography. The 20 ns/16 kHz amplified spontaneous emission (ASE) from a mirror-less CuBr discharge tube was used to illuminate the target and the brightness of its image was amplified by the same discharge tube. It is shown that the relatively weak illumination from ASE is strong enough to be recorded every laser shot on a 100 ASA film and would be useful in the study of the biology samples. A gated high-speed photography was demonstrated using a normal CuBr laser to illuminate a target at long distance and its image was amplified by another CuBr discharge tube. The image-brightness amplifier acts not only as an atom resonance filter, but also a distance-selective device by controlling the relative delay time of these two discharge tubes. Such a gated high-speed photography technique may be useful in the underwater imaging.

The possibility of solid-state ring laser (SSRL) as a gyroscope was examined first in a frame of diode-laser pumped monolithic Nd:YAG ring resonator. Weak coupling between the counter-propagating waves results in antiphase sinusoidal self-modulation of the intensities. It is observed that the self-modulation frequencies depend on the external rotation rate.

In this study, a YAG frequency-doubled pulsed laser with no Q-switch was constructed for the optical measurements under high-velocity phenomena. The laser consisted of the doubled-elliptical pump cavity with a Nd:YAG rod and two xenon flash lamps, the optical resonator with a KTP crystal, and the high-voltage pulsed electrical source. The stimulated emission of the frequency-doubled pulsed laser of 532 nm in wavelength was confirmed by a spectrometer. The laser output power was estimated to be larger than 4 kW by a pyroelectric joulemeter. The delay time from trigger signal and the effective time duration were about 40 and 65 microsecond(s) , respectively.

Analysis of passive mode-locking for lasers with Kerr intracavity nonlinear elements has been presented. Nonlinear diffraction losses, which result from the transverse beam size changes produced by self- focusing, has been determined. The transient evolution and the stability regime of a stationary pulse have been investigated. We have obtained an expression of the pulse duration as a function of the laser system parameters: the refractive index nonlinearity, the intracavity aperture size, the linear diffraction loss, and so on. Optimum conditions for the shaping of ultrashort pulses have been found.

A specially developed femtosecond solid-state laser source destined for dynamic calibration of streak cameras with picosecond and sub-picosecond temporal resolution is described.

On base of coherent manganese vapor laser it was made high time-spatial resolved framing device. High speed framing registration has been used for the optical quality interferometric measurements in excimer and iodine lasers.

The R & D results of manganese vapor laser as light source for high speed framing registration are presented. The high spatial coherence of this laser have been achieved by using of a conjugate cavity. High reproducibility of the coherent characteristics was observed at pulse repetition up to 10 s^-1.

A controlled-frequency-spectrum-transformation single-shot phase- sensitive autocorrelation technique is described, which enables for the first time the complete characterization of the intensity and phase of arbitrary ultrashort optical pulses by using second-order- autocorrelation.

This paper describes the performances of Cr:GaAs photoconductive switch that is conducted with a gain switch semiconductor laser. This photoconductive switch generates stable and reliable electrical pulses. This system has compactness, high efficiency, and bright application prospects.

Electro-Optic (EO) sampling is a potentially powerful technique to characterize very high speed electrical wave forms in the time domain and to examine wave forms internal to integrated circuits, where external connections cannot be made. It is more attractive when the semiconductor laser is used as a laser source because of its compactness, inexpensiveness and arbitrary repetition rate for gain-switched operation. However such laser systems have limitations for practical use, i.e. the poor voltage sensitivity, which is caused by laser power. Noise suppression is the most important point in EO sampling system using a laser diode.

Combination of backward Brillouin scattering and grating compressor has made possible the production of extremely bright laser source. The first step towards the realization of such a source is the development of small size laser system. Using this suggestion, 100 time pulse compression of a 5 ns initial pulse down to 30 ps is obtained.

The steady-state characteristics of the femtosecond Ti:sapphire lasers are discussed with the help of the mode-locked equation derived by us. The characteristics are both valuable in the research of the mode- locking mechanism and guidable to optimized design of the cavity configuration. The optimum parameters of the cavity configuration are reported. With the optimum arrangement, the self-mode-locked Ti:sapphire lasers produces pulses as short as 60 fs, and for the pump power of 4 W, the average output power can exceed 300 mW. The pump power threshold for CW laser oscillation is 1 W, and for self-mode-locked oscillation is about 3 W.

The sequential pulsed white light source is widely used for synchronous illumination in high-speed photography. Usually, the move range of the object is large and wide spectral coverage of the light source is required. In this case, laser is not a suitable illumination light source. Thus it is better to use a gas discharge tube. When discharge energy of every flash is larger than 10 J, and a flash frequency reaches 2 X 10⁴ Hz, the output power of the circuit should be high up to several hundred KW. In fact, the repetition frequency of the strobe will be restricted by charge velocity of the circuit if a traditional monocircuit for charge and discharge is used. In addition, high-voltage resistant and large current quick switch is very expensive. So the above mentioned traditional type of strobe is difficult to spread widely. We have designed and tested a novel high frequency strobe driven by multicircuit. The strobe consists of a few charge and discharge circuits with several small thyratrons, flash Xe tube and its preionization circuit, trigger generator and amplifier, and trigger signal distributor. Its principal parameters are summarized as follows: flash pulse width, 0.2-10 microsecond(s) ; average power, 1 X 10⁴ approximately equals 1 X 10⁷ W; discharge energy per flash, 1 approximately equals 15 J; flash frequency, 1 X 10³ approximately equals 5 X 10⁵ Hz. In this report, we described the principle of the strobe and the choice of the main parameters.

Cross-correlation method for determination of the temporal profile of the ultrashort light pulse (USP) has been substantiated theoretically and checked experimentally. The method has been checked experimentally at the YAG:nd laser wavelength of 1,064 micrometers .

An experimental setup of photon counting real-time image acquisition system is introduced, wherein a photon image head (an image intensifier with high radiant emittance gain) is coupled with a high frame rate CCD camera by a super powerful relay lens. The restrictions on luminous emittance of object are analyzed for multiphoton and single photon imaging modes. The methods of determining readout noise are introduced. The application examples of system in adaptive optics wavefront sensor operated with a faint object, and in experimental study on the optical wave-particle duality and the uncertainty relation are presented.

A prototype of a PC-based motion analysis system specialized for the car-crash test with 2D and 3D analysis capabilities was developed. The core of the proposed motion analysis system is the film-to-video conversion and the semiautomatic marker tracking. Construction of the converter using a 16 mm film projector and a CCD camera is currently undergoing. The semiautomatic marker tracking system was tested in an outdoor pilot experiment a with a small-sized passenger car. A film-to- video converter, a PC with a frame grabber, an RGB video monitor and the tracking software are the components of the tracking system. A location- prediction & marker-detection algorithm was embedded in the tracking software of automatic marker detection. Other data analysis features were also discussed.

This paper proposes a method for offering information and realizing communication to the deaf-mute. The deaf-mute communicates with another person by means of sign language, but most people are unfamiliar with it. This method enables to convert text data into the corresponding image sequences for Korean sign language (KSL). Using a general 3D shape model of the upper body leads to generating the 3D motions of KSL. It is necessary to construct the general 3D shape model considering the anatomical structure of the human body. To obtain a personal 3D shape model, this general model is to adjust to the personal base images. Image synthesis for KSL consists of deforming a personal 3D shape model and texture-mapping the personal images onto the deformed model. The 3D motions for KSL have the facial expressions and the 3D movements of the head, trunk, arms and hands and are parameterized for easily deforming the model. These motion parameters of the upper body are extracted from a skilled signer's motion for each KSL and are stored to the database. Editing the parameters according to the inputs of text data yields to generate the image sequences of 3D motions.

This paper describes the digital image processing techniques of a thermal observation system, which is a serial/parallel scan and standard TV display type using a SPRITE (Signal PRocessing In The Element) detector. The designed digital electronics has two major signal processing stages: a high speed digital scan converter and an autoregressive (AR) filter. The digital scan converter is designed with analog-to-digital converter (ADC) and dual port RAM that can carry out reading and writing simultaneously, thus enabling compact scan conversion. The scan converter reformats the five parallel analog signals generated from the detector elements into serial digital signals compatible with RS-170 video rate. For the improvement of signal-to- noise ratio and compensation for the gamma effect of the monitor, we have implemented a real time 1st order AR filter that adopts frame averaging method. With the look-up-table (LUT) ROM that contains the frame averaging factors and the gamma coefficients, this digital filter performs the noise reduction and the gamma correction at the same time. This digital image processor has been proven to provide excellent image quality and superior detection capability for distant targets at night time.

The next generation coding techniques are closely connected to the major techniques on computer vision and computer graphics especially in the field of segmentation. This paper deals with a study on the foreground and background segmentation in videophone-type sequence and tries to use it for quality enhancement of reconstructed image. A simple 1D high-pass mask is used to reduce redundant correlated image information. And an edge information from edge operator is incorporated to help to find the contour of object boundary. An appropriate bridging strategy is proposed as one part of constructing the linear contour. Simulation results show that the proposed algorithm works well for videophone-type sequence and improves the reconstructed image quality considerably.

This paper proposes a method for extracting facial feature points automatically using deformable templates whose shape and brightness are changeable. Also, we show adjustment of 3D shape model on facial images using the extracted feature points. The deformable templates are constructed with a mean facial image. The mean facial image is obtained by adjusting 3D shape model on 50 facial images and meaning those. There are the templates for whole face and 6 kinds of facial parts (right eyebrow, left eyebrow, right eye, left eye, nose and mouth). The whole face templates have 7 sizes and 7 levels of brightness for each size. The templates for each facial part have 7 sizes. This algorithm begins from searching face region with the whole face templates. The second step determines candidate region for each facial part by referring the searched face region. The third step searches each facial parts in each candidates region in the order of eyes, nose, eyebrows and mouth. The 3D shape model is adjusted on the facial images using the searched feature points. This method is more stable in extracting feature points than the traditional method with only shape because the shape and brightness of our templates are changeable.

Research results for parameters of optical signals arising under investigation of gas-dynamic processing with the application of fiber- optic systems are presented. Analysis of factors affecting these signals shape and type is given for some experiment arrangements.

It is narrated that the optical signal is transmitted by an optical fiber in detail. The optimum gap from the reception point of optical fiber to measured surface of explosive is determined after a lot of experiments, and the cause lost signal from optical fiber and the mechanism forming optical signal in this gap are briefly introduced. Thus a great deal of optical signals are lost in experiments. It is solved that a great deal of optical signals are lost in experiment.

Dealing with dynamic behavior of solids, flows, detonator initiation, high explosives properties, shock waves and other fast processes, implies a large amount of metrology problems. When studies on shock waves began, forty five years ago, only flash X-ray radiography achieving chronometric measurements was developed, in order to investigate shaped charges jets. This technique has also been widely used in detonics because it does not affect hydrodymanic phenomena. Since that time, a large amount of data has been gathered and has allowed physicists to confirm many theories. Later pulsed high energy radiographic machines emitting X-rays have allowed large images record of voluminous objects containing dense materials (with high atomic numbers) and therefore very absorbing. Our laboratory has been working in this field for more than 30 years. A great deal of effort has been spent to enhance the radiographic capabilities of our X-ray machines. High dose levels and better spot size diameter of X-ray sources have allowed quite good records for a better understanding on material densities and boundaries. During the same period of time many works were led on the detection of low X-ray fluences. We present in this communication the main studies developed in that field on cells of light screens coupled with visible film and on microchannel plates image intensifiers.

The constructions and the fundamental studies of high-speed soft x-ray generators which can be used for performing biomedical radiography with maximum photon energies of less than 150 keV are described. The flash x- ray generators having cold-cathode radiation tubes are classified to four types: (1) high-intensity single flash x-ray generators, (2) dual- energy flash x-ray generators, (3) single plasma flash x-ray generators, and (4) repetitive compact flash x-ray generators. In general, when we employed flash x-ray generators with diodes, the pulse widths had values of less than 200 ns. In the case where we employed a long-duration flash x-ray generator having a triode, the width could be increased up to about 40 microsecond(s) . The maximum tube currents achieved with high-intensity generators were more than 10 kA, and the maximum repetition rate of a compact generator has a value of about 0.4 kHz. In order to obtain higher repetition rates of more than 1 kHz, we developed three types of pulsed x-ray generators having hot-cathode tubes as follows: (5) a 30 kHz high-dose-rate generator, (6) a 30 kHz variable-duration microsecond generator, and (7) two 10 kHz high-photon-energy generators. When a high-dose-rate generator was employed, the maximum tube current can be increased up to about 2 A by applying the positive grid voltage. In contrast, as the duration was controlled in a microsecond range by using a microsecond generator, the sufficient x-ray intensities for the normal radiography were obtained. The maximum photon energy could be increased more than 100 keV using a high-voltage transformer in conjunction with a diode. Using these generators, we performed various kinds of high- speed soft radiographies.

The passade of the bremsstrahlung spectrum with boundary energy equal to 70 MeV through the lead and iron absorbers whose thickness corresponds to the widely spread investigated objects is calculated. Further, by applying the statistical modelling method the calculation of the interaction between the obtained spectra of the gamma radiation and the converting plate of the gas discharge converter (GDC) is performed. The trajectories of electrons entering into gas volume are followed and the radial distribution of the energy losses in gas is calculated. It is shown that unsharpness being found in the gas layer depends on the distance from the converter electrode. The calculation of the gas amplification processes is carried out, and on the basis of this calculation it is shown that by choosing the high-voltage pulse form, duration and amplitude of the GDC power supply it is possible to achieve the essential improvement of the GDC spatial resolution.

Consideration is given to the two frame radiographic facility to study fast-running processes on the basis of the air-cored pulsed betatrons. The facility with accelerators comprised, the method of synchronizing accelerators between themselves and with the process under investigation are described.

A 10 MeV linear induction accelerator has been built for use in flash radiography. This machine consists of a 1 MeV injector followed by 28 accelerating induction cells. Each accelerating cell adds 320 kV to the electron beam. An electron beam of 2 kA with focal spot diameter < 4 mm on the target has been obtained. Exposure dose at a distance of 1 meter is 90 R, and the pulse length is 90 ns. In this paper the construction of the accelerator and its operation characteristics are presented.

The radiographic characteristics of a high-intensity plasma flash x-ray generator having a solid-target (anode) radiation tube are described. This generator consisted of the following essential components; a high- voltage power supply, a low-impedance coaxial transmission line, a coaxial oil condenser of 0.2 (mu) F, a turbo-molecular pump, a thyratron pulser as a trigger device, and a flash x-ray triode having a rod-shaped long double anode; a 2.0 mm inner tungsten anode was embedded in 3.0 mm copper anode. The high-voltage condenser was charged from 40 to 60 kV by the power supply, and the electric charges in the condenser were discharged to the tube after triggering the cathode electrode. The maximum tube voltage was equivalent to the charged voltage of the main condenser, and the voltage decreased after the triggering. Both the tube voltage and the current displayed damped oscillations, and the maximum tube current was less than 20 kA. The pulse height of the flash x rays substantially increased according to increases in the charged voltage, and the x-ray durations had values of a few microseconds. The plasma x- ray source substantially grew when the charged voltage was increased. The flash x-ray spectra from the plasma x-ray source were measured by a transmission-type spectrometer having a LiF curved crystal of 0.5 mm in thickness. Compared to the intensities of copper K(alpha) ₁ and K(alpha) ₂ including nondiagram lines increased by using the double target.

The constructions and the fundamental studies of two types of kilohertz- range pulsed x-ray generators are described. The multiple-pulse generator was primarily designed in order to increase the x-ray intensities even when the x-ray duration increased. In contrast, as the damped oscillation of the tube voltage was prevented by using a high- voltage diode in conjunction with a resistor, we designed the single- pulse generator to obtain short x-ray durations. Each generator employed the following essential components: a thyratron pulser, a high-voltage transformer, a CD power supply for the cathode (filament), and an x-ray tube. The main condenser in the pulser was charged from 8 to 16 kV, and the electric charges in the condenser were repetitively discharged to the primary coil of the transformer. Because the high-voltage impulses were then applied to the x-ray tube, repetitive x rays were generated. The x-ray tube was of a diode having a hot-cathode with a maximum temperature of about 2,000 K. The tube voltage increased in proportion to the charged voltage, and the maximum value was about 110 kV. The tube current was primarily determined by both the filament temperature and the tube voltage and has values of less than 1 A. The minimum widths of the pulsed x rays by the single type were less than 250 ns, and the maximum repetition rate was about 10 kHz.

The fundamental studies on a high-intensity flash vacuum-ultraviolet (VUV) generator for producing water-window flash x rays are described. This generator consisted of the following essential components: a high- voltage power supply, a coaxial high-voltage pulser having a 0.2 (mu) F condenser, a Krytron pulser as a trigger device, a turbo molecular pump, and a VUV tube. The VUV tube employed a surface-discharge ferrite substrate having two copper electrodes and was evacuated by the pump with a pressure of 1.3 X 10^-3 Pa. The condenser in the pulser was charged from 10 to 30 kV by the power supply, and the electric charges in the condenser were discharged to the radiation tube after closing a gap switch by the Krytron pulser. Then the flash VUV rays were generated. The maximum output voltage from the pulser was almost equivalent to the charged voltage, and both the tube voltage and current displayed damped oscillations. The maximum values of the tube voltage and current were approximately 23 kV and 13 kA, respectively. Since the effective accelerating voltage was substantially decreased by the substrate, soft x rays were easily generated. The pulse durations of the VUV rays including water window x rays were nearly equivalent to those of the damped oscillations of the voltage and current, and their values were less than 30 microsecond(s) .

The fundamental studies on a dual-energy flash x-ray generator for performing the energy-selective two-direction radiography are described. This generator consisted of the following components: a negative high- voltage power supply, a polarity-inversion-type high-voltage pulser having a 5 nF combined ceramic condenser, a turbo molecular pump, and two flash x-ray tubes. The condenser in the pulser was charged from -60 to -80 kV, and the electric charges in the condenser were discharged to two x-ray tubes. The maximum output voltage from the pulser was about -1.5 times the charged voltage because the cable transmission line was employed. Using a tube, the maximum tube voltage was about 110 kV. The maximum tube current and the x-ray intensity were less than 3 kA and 5 (mu) C/kg at 0.5 m per pulse, respectively. In contrast, the tube current and the intensity has approximately half the above values when two tubes were employed. The pulse widths were less than 200 ns, and two shots of flash x rays were obtained simultaneously. Each photon energy of flash x rays can be changed by controlling the space between the anode and cathode electrodes.

SPECTRA is a powerful image simulation system which supported our fundamental research on the optimum control of the flash x-ray spectrum. We have extended this system to manage the real images obtained from various imaging media including the Computed Radiography (CR) system. With the extended SPECTRA we have derived the approximating functions which represented the relationship between the total bremsstrahlung spectrum intensity and the gray level of the images obtained from an imaging medium. These functions well fitted in with our data. These functions were built in SPECTRA and were used for estimating the thickness of the absorber material at arbitrary location on the real image. As a test object for evaluating our estimation method, we used a step-shaped solid model of aluminum which had 3 steps of 5.02, 10.04 and 15.08 mm in thickness, respectively. Estimated thicknesses of aluminum steps were 3.60, 9.40 and 12.2 mm, respectively.

A 30 kHz pulsed x-ray generator utilizing a hot-cathode triode in conjunction with a new type of grid controller for varying the x-ray duration is described. This generator consisted of the following essential components: a constant high-voltage power supply, a high- voltage main condenser of 97 nF, a DC power supply for the filament (hot cathode), and a hot-cathode triode. The high-voltage main condenser was charged from 50 to 70 kV by the power supply, and the electric charges in the condenser were discharged to the x-ray tube repetitively by the grid controller. The maximum values of the grid voltage (negative value) and the tube current were about -2.2 kV and 0.6 A, respectively. The x-ray duration was controlled by the time constant of the grid controller and the electron cutoff voltage. The x-ray intensity with a pulse width of 70 microsecond(s) and a charged voltage of 70 kV had a value of 1.26 (mu) C kg-1) at 0.5 m per pulse. The maximum repetition rate was about 30 kHz, and the size of the x-ray source had a value of 3.5 X 3.5 mm.

The constructions and the fundamental studies of a flash x-ray generator having a liquid-anode diode are described. This flash x-ray generator consisted of the following essential components: a high-voltage power supply, a high-voltage pulser, a thyratron pulser as a trigger device, an oil diffusion pump, and a flash x-ray tube. The main condenser was negatively charged from 50 to 70 kV by the power supply, and the electric charges in the condenser were discharged to the x-ray tube after closing a gap switch by using the thyratron pulser. The flash x- ray tube was of a diode type having a mercury anode and a ferrite cathode. The pressure of the tube was primarily determined by the steam pressure of mercury as a function of temperature. The maximum output voltage from the pulser was about -1 times the charged voltage. The maximum tube voltage and current were approximately 60 kV and 3 kA, respectively, with a charged voltage of -60 kV and a space between the anode and cathode electrodes (AC space) of 2.0 mm. The pulse widths of flash x rays were about 50 ns, and the x-ray intensity measured by a thermoluminescence dosimeter had a value of about 2.5 (mu) C/kg at 0.3 m per pulse with a charged voltage of -70 kV and an AC space of 1.0 mm.

We have developed a new assembly for the shock compaction of difficult- to-consolidate powder such as intermetal compounds or ceramic materials. We have successfully obtained crack free bulks of consolidated sample from several kinds of powders for example TiAl alloy or Si₃N₄ powder etc, using this assembly. This assembly consists of three parts. They are, an explosive container, a water chamber and a powder container. Once an explosive is detonated in the container, the detonation wave occurs and propagates to impinge on the water in the water chamber. When the detonation wave impinges on the water, an underwater shock wave occurs immediately. The underwater shock wave interacts with the solid wall in the chamber, converging its strength as it propagates down stream. Finally, the converged underwater shock wave enters into the powder container to consolidate the powder. The mechanism of this process described above has not yet been fully analyzed. In this paper, the interaction process between the detonating wave and the water are investigated by the streak photograph taken by an image converter camera. The underwater shock wave is accelerated in a short time up to its final velocity, which is slightly larger than that determined by the impedance match method. The converging process of the underwater shock wave was also understood by the high speed photograph obtained by framing photographs using shadowgraph system. The incident shock wave comes up to about 18 GPa after being converged by the wall of the pressure chamber. Finally, we suggest the most suitable design of pressure assembly.

Photography's inestimable contribution to science and technology is beyond question. Applied photography, or in this case applied cinematography, is that area of work which assumes an integral part of a research project and where the results of photographic analysis form a major source of information. In military research and development or testing there are various fast events that need to be recorded and analyzed. High speed cameras allow the capture of movement too fast to be recognized by the human eye and provide data that is essential for the analysis of such events.

It is important to use high time-resolved photonics system and to use good quality specimens for the shock-wave measurements of ceramics, because the sound velocities are very fast, and their shock compression behaviors are complicated compared with those of metals. We produced the rotating-mirror type streak camera with the maximum streak rate to film of faster than 10 mm/microsecond(s) and the intense Xenon-flash lamp, and have been measuring the Hugoniot data of various kinds of ceramics by the inclined-mirror method. In this report, the high-velocity streak photonics system combined with a powder gun is described, and the measurement experiments on some hard ceramics (Si₃N₄, AlN and B₄C ceramics) are reviewed.

A variety of possible image converter and streak camera technique applications for the junction lasers spectral-spatial and spectral- temporal radiation characteristics research in nano- and picosecond ranges is considered. Traditional methods of laser dynamics research, which are based on the streak camera technique, commonly use the time sweeps of near (far) field or the spectrally resolved near field of laser radiation. In the research of the laser diodes phase-locked arrays (LD PLA) dynamics it is important to analyze an instant spatial structure of each radiation mode of a complex multielement laser structure. It appears to be possible, to transform an usual 2D image of the spectral-spatial distribution (SSD) into an 1D and to sweep it in time. Examples of 1D SSD time sweeps for two- and three-element LD PLA are presented and their features are discussed. These spatially resolved spectral-temporal sweeps display an instant spatial structure of each laser radiation mode for any moment of a continuous time sweep. The given method can be applied also for the investigation of a broad area LD spectral dynamics and specific high-speed processes in optics.

Since High-Speed-Photography is used for the analysis of accelerated motions at safety tests within the automotive industry, light was always very important. In the beginning the tests had been performed under natural daylight, which limited the efficiency of the complete test stand, due to the unpredictable outdoor conditions. Due to the use of artificial light sources, which open the possibilities for indoor testing, the performance of such tests was much more controllable and, which was very important, reproducible. Till today several light sources and techniques had been used. Regarding the performance, the efficiency, the applicability and the economy, this lecture will describe some of the benefits and disadvantages of different light sources and systems. Finally an overview on the use of modern lighting systems for various applications ranges as, crash-barrier test, sled bench test, air-bag static test and different installation techniques to increase the utility of such lighting system, will be given.

Within the automotive industry, especially for the development and improvement of safety systems, we find a lot of high accelerated motions, that can not be followed and consequently not be analyzed by human eye. For the vehicle safety tests at AUDI, which are performed as 'Crash Tests', 'Sled Tests' and 'Static Component Tests', 'Stalex', 'Hycam', and 'Locam' cameras are in use. Nowadays the automobile production is inconceivable without the use of high speed cameras.

Automobile crash tests are filmed in order to demonstrate the resistance of the vehicles and the safety guaranteed to the passengers. The conventional analysis of the high speed films works by manual measurement of specified markers in each frame. In cooperation with the automobile industry the computer system MOTION was designed which automizes all steps necessary for generation of calibrated trajectories. It provides all hardware features for scanning, displaying and storage of image sequences as well as an extensive software package with an user interface adapted to the task. The robustness, accuracy and reproducibility of the evaluated results is achieved by a new developed tracking algorithm based on a special marker type.

The analysis of complex movement processes in the development of engines and major components using high speed cameras follows a long tradition at Mercedes-Benz. Already in 1 939 aircraft engines were perfected with the help of a high speed film crnera. In 1959 we carried out the first passenger car crash and rollover tests - this at a time when the concept of "crashworthiness and accident safety" was still insignificant. It was then that my fascination for high speed film analysis began which, from then on, was never to leave me. Other investigations resulted in the rotary engine and prechamber and fuel injection systems - not forgetting the developent of the airbag which, without the use of high speed cameras, would, without doubt, not have reached the high standard of development it enjoys today.

Since the beginning of the use of high speed cameras for crash and hyge- testing substantial changements have taken place. Both the high speed cameras and the electronic control equipment are more sophisticated nowadays. With regard to high speed equipment, a short historical retrospective view will show that concerning high speed cameras, the improvements are mainly concentrated in design details, where as the electronic control equipment has taken full advantage of the rapid progress in electronic and computer technology in the course of the last decades. Nowadays many companies and institutes involved in crash and hyge-testing wish to perform this testing, as far as possible, as an automatic computer controlled routine in order to maintain and improve security and quality. By means of several in practice realize solutions, it will be shown how their requirements could be met.

High-speed photography has been used to make kinematic measurements for more than 120 years, but only in the last twenty-five years have significant advances been made in data capture techniques. In the 1970's, generalized photogrammetric methods for reconstructing two- and three-dimensional trajectories were devised, but in practice, few investigators could find the time to manually extract coordinate data from hundreds, if not thousands, of images. The 1980's saw the introduction of consumer vide and desktop computing, and the shift to electronic imaging began. New hardware, and more sophisticated software, made it possible to exploit the potential of an old technology. By the mid 1980's, investigators could extract coordinate data from a video signal, store the data in a workstation, and reconstruct 3D trajectories soon after a test has been conducted. 4D VIDEO was formed in October 1988. We have found that there is depth and breadth to the potential users of image-based motion measurement. However, few end-users are interested in the procedures required to capture and manipulate the coordinate data. Further, we have found that the sophisticated procedures required to extract kinematic data from images have become a burden in their own right. Techniques are required that minimize the effort of the end-user and provide results quickly and efficiently.

We have developed a spark gap system which permits PMAS to be used for the recording of high speed events. PMAS is a high speed photographic facility which consists of a double spark generator used as an ultra short duration light source, an optical system, and on an electronic control unit which provides delay before and between successive frames. In applying the PMAS to record light emitting high speed phenomena, a principal problem has been the lack of reliable intense light source with very short radiating times and restricted radiating areas. At the same time it is desirable to increase the illumination power as far as possible. In order to resolve the problem, we developed a groove type spark gap light source on the assumption that the electric discharge occurs along and is confined to the groove, and that the circular character of the spark channel would insure continuous electric discharge action while preventing pinching. With a sequental operation of such spark gaps, PMAS has been used in spray atomization, ballistic, detonics, schlieren studies, shadowgraph, etc.

When an explosive detonates in water, it is well known that an underwater shock wave occurs immediately and propagates into the water. Generally speaking, the explosion phenomena near the explosives are too complex for us to understand the shock generating mechanism. Although the characteristics of underwater shock waves far from the explosives have already been investigated by many researchers, the behavior near the explosives has not yet been sufficiently investigated. We have been approaching the metal processing using the underwater shock waves. In this approach, we used the underwater shock waves which were caused in the region close to the explosive. Therefore it is very important to know how the generation and the propagation of the underwater shock waves occurred by the underwater explosion of the explosive. Once the explosives detonate in water, the pressure just behind the detonation wave rises abruptly up to its Chapman-Jougel value. The pressure of the water adjacent to the explosives also immediately rises to its suitable pressure value. The phenomena near the explosives were unsteady, so we used an optical technique to determine their characteristics. We also used a numerical procedure to obtain their characteristics more precisely. Two kinds of explosives were used in experiments. One was a detonating cord and the other a plastic explosive called SEP. The characteristics of underwater shock waves were investigated by shadow graphs and streak photographs. We used a couple Lagrangian-Eulerian method in calculations.

In various underwater explosive metal processing such as a forming, a cutting or a welding, we have applied suitable regulated shock waves. For example, in the case of making holes on the wall of a pipe from the inside, it is necessary to get the plane underwater shock wave to move perpendicular to its direction of progress. In the case of metal forming, an underwater shock wave with a broad pressure distribution is required. It is very important to know what is the best configuration of the underwater shock wave for the purpose of metal processing. In our case, the explosives are pasted on a plate called a reflector to use their energy efficiently. However, the characteristics of an underwater shock wave generated by detonating these explosives have not yet been understood. The effects of the reflector on the strength and on the configurations of an underwater shock wave are investigated by high speed photography and by an image converter camera. The effects of the angle of the reflector are also investigated. It was confirmed that the strength of the underwater shock wave increases as the angle of the reflector becomes lesser.

When a spark discharge occurs at the first focal point of a semiellipsoid or a reflector located in water, a spherical shock wave is produced. A part of the wave spreads without reflecting on the reflector and is called direct wave in this paper. Another part reflects on the semiellipsoid and converges near the second focal point, that is named the focusing wave, and locally produces a high pressure. This phenomenon is applied to disintegrators of kidney stone. But it is concerned that cavitation bubbles induced in the body by the expansion wave following the focusing wave will injure human tissue around kidney stone. In this paper, in order to examine what happens when shock waves strike bubbles on human tissue, the aspect that an air bubble is truck by the spherical shock wave or its behavior is visualized by the schlieren system and its photographs are taken using an image converter camera. Besides,the variation of the pressure amplitude caused by the shock wave and the flow of water around the bubble is measured with a pressure probe.

Manufacturing techniques using shock waves generated by underwater explosion have been developed and studied for many years. The major advantages of these techniques are that the pressure acts for a relatively long duration, and there are no thermal effects on the materials. We have been approaching the utilization of the underwater shock wave for various metal processing methods such as in metal forming, explosive welding and shock compacting of difficult-to- consolidate powder. It is necessary to control the underwater shock waves with regard to the processing objectives. In many cases, the underwater shock waves have been used quite close to the explosives. The properties of the underwater shock wave in the region far from the origin of the explosion (more than 1000 mm) have been investigated since long time, but those near the explosive are not yet known. In this paper, we have tried to make clear the properties of shock waves near the explosive. The pressure of the underwater shock wave generated by a detonation cord was measured by a pressure transducer, which was made by a tungsten bar with semiconductor gauges. We found that the pressure of the underwater shock waves decreased almost exponentially. We also investigated the properties of the underwater shock waves by high speed photography. Two kinds of high speed photography were used in experiments. One was the streak photograph and the other was the shadow graph. The propagating of the underwater shock waves was made to clear by framing photographs with an image converter camera. The Profiles of the underwater shock waves were also obtained from high speed photography using a pulses laser as an optical source. Using these profiles of the underwater shock wave, we could obtain the velocity of the shock wave front, and finally we could obtain the pressure across the underwater shock waves by using the Rankine-Hugoniot condition. The pressure obtained by optical measurement agreed with the results obtained by the transducer. As a result of these experiments, the attenuating processes of underwater shock waves, even those near the explosives, were understood.

A spherical shock wave induced by an under water spark discharge at the first focal point of a semiellipsoid or a reflector, converges near the second focal point and a high pressure is locally produced. This phenomenon is applied to disintegrators of kidney stone by extracorporeal shock waves on the assumption that the acoustic characteristics in human tissue are very similar to those in water. But the behavior of the shock wave which propagates from water to human tissue has been unknown still now. In this paper, we observe the behavior of the shock waves which propagates through two kinds of media, that is, water and silicone oil and its photographs are taken with a high-speed camera (image converter camera) by means of the schlieren system. Besides, a semiellipsoid is modified to make the spherical shock wave produced at its focal point converge at its second one taking account of the refraction at the boundary between water and silicone oil. The result that it is possible to make the spherical shock wave converge across the boundary between water and silicone oil with the modified semiellipsoid is obtained.

For the design of barriers for detonation wave shapers in shaped charges, the shock wave attenuation characteristics of different materials or composite arrangements had to be tested. This paper will explain a test configuration for the diagnostic of the shock wave attenuation of homogeneous and sandwiched inert materials, which measures the delay time between the detonation of a doner and an acceptor charge. Applying the double-flash-gap technique, the analyzed pressure levels render possible conclusions about the existence of divergent or convergent detonation waves.

Double-exposed holographic interferograms of 3D shock wave phenomena are presented. Details of experiments and the equipment used are also briefly described. Advantages of this kind of visualization technique are pointed out with the examples of a normal shock generated in an air shock tube for a straight channel, T-junction and sudden enlargement channels, channels with differently shaped obstacles.