This paper focuses on the recent advances in tactical Anti- tank (ATGM) systems and related technologies. The growth profile of ATGM systems and related technologies has been discussed with special emphasis on technologies pertaining to guidance systems. 'Fire and forget' and 'Top attach' capabilities are the most important operational requirements of the third generation ATGM systems. Realization of 'Fire and forget' capability for tactical ATGMs calls for use of a passive or active homing system. The need for such a system has been the main driving factor for mobilizing the advanced technologies relating to IR and Millimetric Wave seeker based guidance systems. Generic design considerations and system constraints as well as technological aspects of these two types of guidance systems are covered. The 'Top attack' requirement calls for optimization of suitable trajectory schemes and it also impose design constants, mainly on the homing seeker. Use of tandem shaped charge warhead is essential to defeat modern tanks equipped with Explosive Reactive Armor. The implications of using the tandem shaped charge warhead on the design of the seeker as well as at system level design are briefly analyzed. In the concluding part, the emerging technological trends relating to ATGM systems with focus on guidance systems are presented.

The detection of targets in broad and highly cluttered scenes is an ongoing challenge for imagin electro-optic technology. We are interested in designing new imaging devices that provide optimal detection of targets in broad cluttered landscapes. Our approach is to employ image fusion where images from a number of electro-optic bands provide the input to algorithms for target detection. The aim is to produce images where the background clutter is suppressed and potential targets are highlighted either by brightness to color. Successful algorithms provide the basis for new sensor designs. This paper discusses the process of image enhancements and new sensor designs.

In this work, we propose a novel thresholding method to simplify the procedure of the binary joint transform correlator. Unlike the normal binary joint transform correlator which thresholds on the power spectra of both the reference image and the target image, we threshold on the power spectra of the reference image only. With this technique the additional on-line recording of the power spectra of the target is avoided. Therefore the procedure of the recognition is as simple as that of the normal joint transform correlator. We then extend the binary joint transform correlator to circular harmonic expansion to achieve the rotation invariant optical pattern recognition. We use a computer to decompose the reference image into a sum of circular harmonic components and form an input of the joint transform correlator with the first-order circular harmonic component and the target image. By use of this technique, we achieve circular-harmonic-based binary joint transform correlation with good performance merits. Computer simulation results and 3D output correlation profiles are presented.

Technological breakthroughs in the field of imaging and non- imaging sensor sand the related signal processors helped the military users to achieve 'force multiplication'. Present day 'smart-weapon systems' are being converted to 'brilliant-weapon systems' to bridge the gap until the most potent new 'fourth generation systems' come on line based on nanotechnology. The recent military tactics have evolved to take advantage of ever improving technologies to improve the quality and performance over time. The drive behind these technologies is to get a first-pass-mission-success against the target with negligible collateral damage, protecting property and the lives of non-combatants. These technologies revolve around getting target information, detection, designation, guidance, aim-point selection, and mission accomplishment. The effectiveness of these technologies is amply demonstrated during recent wars. This paper brings out the emerging trends in visible/IR/radar smart-sensors and the related signal processing technologies that lead to brilliant guided weapon systems. The purpose of this paper is to give an overview to the readers about futuristic systems. This paper also addresses various system configurations including sensor-fusion.

It is shown that the theoretical limit of the specific information capacity of electronic-vision systems depends only on density of photon flow producing the image and is directly proportional to this density. However, at significant flows the information capacity is restricted by diffraction effects in optics and the capacity of electron storages in pixels. The ultimate information capacity of multispectral electronic-vision systems is evaluated.

A passive hologram guided target designation is more superior than simple matrix or image guided system due to its 3D target acquisition and recognition. To implement this criterion a target hologram was loaded into onboard optics that was a part of a dynamic scanning system. The observed data was compared with onboard target hologram and found that the system accuracy was better than the conventional systems. To make the carrier invisible multi-layer coating were used that resulted in perfect concealing of the carrier. Once the target acquisition is compete the locking system stops further comparison and reorients the carrier direction on to the target. This paper critically overviews general principles involved and experimental furtherance in the field of optically guided target designators. There is say that a perfect control of the electromagnetic spectrum can close the eyes or ears and renders the defence blind and deaf. Normally laser and fiber optic guided missiles ar more popular than the conventional guided missiles but our proposed hologram guidance approach is likely to establish its own technical distinct and novelty.

Gradual development of improved types of sensor, image processing techniques, image fusion capability, innovative optical designs and AR coatings have enabled thermal imaging technology to undergo revolutionary advancements leading to the realization of all time and all weather vision. It has now been possible to have alight weight hand held thermal imaging system using uncooled detectors as well as very long range system for surveillance, target acquisition, tracking and guidance using FPAs. Not only has India made significant progress in the field of thermal imaging but innovative work has been carried out in order to enhance the performance of these systems. This has resulted in the development of a thermal imager giving ranges of 4 Km plus used in 'Fire and Forget' type missile in addition to thermal imagers for AFVs. A state-of-the-art second generation thermal image for airborne application co-developed with M/s TCO, France is under evaluation and testing. Innovative optics design has led to the enhancement of the range capabilities by 1.7 times of a hand held thermal imager of French origin. The paper focuses on intricacies of system as also technological capabilities in India including design capability of most sophisticated IR optical system, Single Point Diamond Turning for generation of aspheric and metal optics, Laser Interferometer for characteristics of lenses, multilayer AR coating and DLC coating, IR Image Evaluation System etc. Work carried out on Binary optics for Thermal Imaging System at IRDE as well as on indigenous development of thermal sensors, ASICs, Rigi-flex PCBs etc. for micro- miniaturization of electronics being progressed at various work centers are also discussed.

The ability of Lasers to generate every high radiation density at remote distances with high precision has made it ideally suited for a variety of applications both in civil and defence areas. While some of the techniques have been evolutionary, some other aspects have led to revolutionary applications. Like many other dual use technologies, rapid growth in Laser technology owes a lot to military research. Hence a brief review of 'Lasers and Defence' is considered appropriate at the turn of the century. Specifically, the direct use of Laser energy offers new optics for Electro- Optic Counter Measures and the High Power Lasers have proved successfully the potential use of Directed Energy Weapon for missile defence and other strategic applications. The technology is ripe to make a major impact in the coming new millennium. The paper present a brief review of this technology as applicable to defence with comments on future potentials.

This paper presents the design of a Compact High Power Diode Array Pumped Nd:CNGG laser employing cusp geometry concentrator for optical coupling in the side pumped configuration. The design addresses two major issues that influence the performance of a Diode Pumped Solid State Laser i.e. choice of suitable laser material and optical coupling scheme. The design employs an Nd:CNGG rod of (phi) 3mm X 10mm dimension, fluid cooled through coaxial flow tube of 5mm diameter. Light from a Quasi-CW laser diode array stack of 2 cm X 1 cm dimension is coupled through a cusp geometry concentrator of 18mm aperture. The system is capable of generating a high average power of approximately 30W at an input of 800W peak power. Optimum performance of the system has been compared with that of Nd:YAG laser operating under similar conditions. Nd:CNGG is found to be more efficient at higher input energies.

In this paper, the laser resonator of the diode-pumped self- mode-locked LNA laser had been analyzed and design by using the methods of linear and nonlinear matrices. Some characteristic parameters of LNA laser, such as the stability, the strength of the self-mode-locking, the change of beam spot size with intracavity normalized power, and nonlinear loss within resonators, have been calculated and optimized. The transform-limited pulses of 631-fs duration, corresponding to spectral width of 2.03-nm were obtained from the LNA laser in experiments. The time-bandwidth product and average output power of the laser were 0.34 and 11mW, respectively. The theoretical simulation result are in good agreement with the experimental parameters of laser.

Diode end-pumped solid-state lasers have the potential to yield high quality laser beams with high efficiency. However, its limited pump volume results in limited output power, usually under 1W. This paper presents a high- efficiency Nd:YVO₄ laser end-pumped by a 15W diode laser bar. An optical-optical efficiency as high as 42 percent and an output laser power of over 3W were obtained with a beam quality factor, M² of less than 1.2 and an output stability of +/- 0.5 percent. Theoretical calculations and experimental data showed that the pumping laser beam was well-matched to the intracavity laser mode.

Active feedback control has been implemented in a Q-switched diode-pumped Nd:YVO₄ laser by monitoring the fluorescence intensity from the laser crystal. When the initial inversion level indicated by the detected fluorescence has reached a predetermined value, Q-switching is initiated. The output Q pulse is stabler with our feedback scheme based on the fluorescence intensity than that with the conventional Q-switching when pumping source is not stable.

Theoretical treatment of nonlinear, three-wave interaction and second harmonic generation (SHG) of Bessel fundamental beams in case of collinear phase matching is reported. The expressions of power and conversion efficiency of SHG of Bessel fundamental beams are found. We also demonstrate operation of SHG pumped by a Nd:YAG Bessel beam using KD*P nonlinear crystal. It is shown that the output of SHG of Bessel beam has a transverse profile and its conversion efficiency is higher than that of the Gaussian beam.

To improve the compactness of Q-switched diode-pumped solid- state lasers, a passively Q-switched diode-end-pumped Nd:YVO₄ laser was constructed using undoped and uncoated GaAs wafers as saturable absorbers as well as output couplers. GaAs wafers with two different thicknesses, 625 micrometers and 500 micrometers , were employed and their corresponding experimental result were compared. The result were also compared with those obtained with an active A-O Q-switch with similar cavity configuration and pumping condition. It is found that the Fabry-Perot effect of the GaAs wafer played an important role in shortening the Q-switched pulses and stabilizing the laser operation. The performance of passive Q-switching using the GaAs wafer with Fabry-Perot effect was better than that of both the passive Q-switching without Fabry-Perot effect and the active A-O Q-switching.

Thermal effects of diode end-pumped Nd:YVO₄ laser are analyzed in this paper. A laser interferometer is set up to determine the optical path difference resulting from thermal effects in crystal under lasing condition. The beam distortions in Nd:YVO₄ rod are measured with a He-Ne laser at wavelength of 632.8nm. The changes of interference patterns record the deformation of the rod with increasing pump power. The experimental and theoretical curves of effective thermal focal lengths versus pump power are obtained, and it is found that the theoretical analysis agrees well with experimental measurement. With the analytic results of thermal effects, an optimized resonator is designed to insure that the laser operates in stable mode with an output power of 3.2W, slope efficiency of 52 percent and M² factor of 1.19.

In this paper, the thermally induced lensing effects of a diode-pumped high-average-power solid-state laser were treated by using appropriate linear and nonlinear matrices. The single- or two-rod resonators are investigated and optimized. Important parameters of the laser resonators, such as the curvature radii of the end mirrors, positions of the rods within resonators, the stabilities, the changes of beam spot size with respect to the diode-pumped power at the center of the laser gain material. The optimized designs for laser resonators not only enables laser to maximize TEM₀₀-volume mode in the laser rod but laser to be insensitive to the fluctuations of diode-pumped power and mechanical misalignment.

Recently, scanning probe lithography by applying an electric field between the tip and the sample has been shown to be a promising technique for nanofabrication. In this paper, we present a novel method of nanofabrication, namely, nanolithography by tip-enhanced laser irradiation. Based on the operation of the laser-assisted scanning tunneling microscope (STM), we established a nanolithography system using tip-enhanced laser irradiation, which was developed from a commercial scanning probe microscope (SPM). In our investigation, the SPM was operated as an STM. During imagin and lithography, the STM is in a constant current mode. The tip is fixed and the sample moves via a tube scanner. Nanolithography software controls the scanner movement in the x and y direction. The SPM has an open architecture, allowing an external laser beam incident on the tip at an incident angle between 0 to 45 degrees. A vertical polarized Nd:YAG pulsed laser with a pulse duration of 7 ns was focused on the surfaces of the tip and the sample. An electrical shutter was introduced to switch the laser irradiation during lithography. Alignment of the laser to the tip-sample gap was performed under a high power charge coupled device microscope. Nanolithography was performed on hydrogen (H)-passivated Si (100) surfaces and H-passivated Ge (100) surface.s The Si samples and the Ge samples were passivated in HF solution. STM tips were homemade electrochemically form a 0.5-mm tungsten wire. Oxide features were created by tip-enhanced laser irradiation. The experimental result will be discussed.

A photoresist films on Si and commercial glass and the paste dried and hardened for forming barrier rib of PDP were directly etched with Ar⁺ laser Nd:YAG laser beam. Exposing the photoresist to a fourth harmonic Nd:YAG laser beam to produce electrodes on the transparent conductive material, the etching threshold laser fluence was 25 J/cm² and the damage of substrate was appeared over the laser fluence of 40 J/cm². The reaction mechanism of the photoresist by the UV laser beam, compared to that by Ar⁺ laser, is photon-assisted ablation. A barrier rib is compared of mixtures that were made form organic gel, glass powder and ceramic powder. Using a second harmonic Nd:YAG laser the threshold laser fluence was 65 mJ/cm² for the barrier rib samples softened at 120 degrees C. The thickness of 130 (mu) M of the samples on the glass was clearly removed without any damage on the glass substrate by laser fluence of 19.5 J/cm². The barrier rib samples on hot plate were etched by Nd:YAG laser with increasing a temperature of the sample. The etch rate at 200 degrees C was 4 times of that at room temperature. Indium tin oxide thin films on lime glass were directly etched using the second and fourth harmonic Nd:YAG laser beam.

A laser writing system using a 325-nm UV laser beam for the fabrication of micro-optical elements is developed. The system consists essentially of a laser source, an optical subsystem, a moveable stage, a computer, and an observation and alignment subsystem. The laser writing system is characterized for the resolution of the system and optimal writing conditions, based on the objective of fabricating micro-optical elements. The resolution of the laser writing systems is 1.2 micrometers , obtained with the 40x UV objective lens at a writing speed of 100 micrometers /s, writing height of 6 micrometers and laser intensity of 1 (mu) W. This agrees fairly well with the calculated theoretical value. We have shown that the laser intensity, writing speed, writing height are three major parameters that determine the optical performance of the micro-optical elements fabricated by the laser writing system. The variation of the thickness and linewidth of the written pattern with the different laser intensities, writing speeds and writing heights are discussed.

GaN thin films have been grown on sapphire substrates by pulsed laser deposition. The thin films deposited at different substrate temperature have been evaluated by x-ray diffraction (XRD), photoluminescence spectroscopy (PL), and x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM). The influences of depositing temperature on surface and optical properties of the GaN thin films have been studied. The XRD result show that the lowest full width at half maximum of x-ray diffraction line of the GaN film was deposited at about 700 degrees C. The photoluminescence (PL) spectra were measured at 7 K. The quantum confinement effects of the nanocrystalline GaN films have been evaluated by the band edge PL peaks. The energy shift of the band edge PL peaks of GaN film deposited at 700 degrees C have been estimated by the effective mass approximation method. The chemical composition and the native oxide of the GaN film surface were investigated by the XPS spectra. Average roughness and surface morphology of the GaN thin films deposited on the sapphire substrates have been evaluated by AFM.

Titanium nitride (TiN) thin films were deposited on hydrogen-terminated silicon substrates by pulsed laser ablation of a ceramic TiN target. A KrF excimer laser with a wavelength of 248 nm and pulse duration of 23 ns was used in our experiments. The vacuum chamber was maintained at a pressure of 10^-5 Torr during the deposition and the substrate temperature ranged from room temperature to 600 degrees C. Nano-indentation and scanning tunneling microscopy (STM) were used to analyze the surface properties of the deposited thin films. The hardness, Young's modulus and morphology of the thin films at different substrate temperatures were investigated. The hardness of the thin films deposited at 600 degrees C was found to be as high as 26 GPa and the Young's modulus approximately 280 GPa. This can be explained by x-ray diffraction measurements. The root mean square roughness and the grain size of the thin films deposited at different substrate temperatures were measured by STM in the contact mode. The relationship between the surface morphology and the crystallinity will be discussed. The x-ray diffraction studies indicated that the grain size of the thin films increased with the substrate temperature and a high quality film can be obtained when the substrate temperature reaches 600 degrees C. Clear improvement of the film hardness and Young's modulus resulted from increasing the substrate temperature.

It has been reported that surface roughening is an effective approach to developing microtextures for high performance magnetic media, increased adherence of coatings on large thermal expansion coefficient mismatched substrates as well as enhanced surface coupling for photodetectors. An important prerequisite is that the controllable and reproducible pattern ought to be produced while minimum adverse effects result on materials. In this study, a novel interface ripple pattern is generated on the surface of the single crystal silicon coated with a thin silicon dioxide layer using a KrF excimer laser at different laser parameters. Experimental result show that the ripple period cannot be predicted by the Rayleigh's diffraction condition as conventional laser induced periodic surface structures on solids. The ripple pattern is firstly seeded at the interface and the tin film capping laser will yield ripple structures following the interface rippling. The amount of absorbed KrF laser energy by the SiO₂/Si interface is identified to have little dependence on film thickness. Within a certain range of laser parameters, ripple pattern grown with laser fluence or number of pulse linearly rather than exponentially. Of particular interest is that ripple period has been found to have a linear dependence on the film thickness at given laser parameters. This controllable ripple pattern provides a sound solution to the cases that require low laser fluence to prevent materials from damage or demand interface roughening which cannot be achieved by conventional techniques. The uniformity of ripple structures can be controlled by properly adjusting the laser parameters between melting and ablation thresholds and the single crystallinity of the Si substrate remains unchanged under laser irradiation at the fluence up to 1.3 J/cm².

It is meaningful to avoid irreversible changes in laser processing of silicon wafer and find out the cause to which the laser induced damage threshold is decreased along with increasing frequency. We investigated the PRE in laser irradiation on c-Si wafer by Raman spectroscopy. Time- resolved Raman spectrometer was developed based on holographic notch filter, optical fiber and optical multichannel analyzer which was applied to detect transient structure changes and stress in silicon wafer under laser shock. The surface morphology was monitored by CCD through a microscope when pulses were on. We applied 1.06 micrometers Nd:YAG laser in our experiment to silicon wafer with and without silicon oxide top layer. Raman spectra was sampled in 100microsecond(s) after laser triggering. Our system could easily detect the surface absorption changes by comparing the intensity before and after laser shock while the surface was not damaged. A reversible weak peak emerged around 500cm^-1 for c-Si with and without silicon oxide. It is attributed to grains under transient stress induced by laser which disappeared after seconds. No such peak is observed in sampling in 1ms after laser triggering. Such emergence of grain states may accelerate the damage process, which will contribute to PRE.

Folded quasi-sealed-off CO₂ laser units of both 1000W continuous wave and 500W mechanically Q-switched are presented. Their characteristics are high beam quality, high reliability, economy, easy to operate and maintain, and acceptable workshop floor area required. The CW laser is used for cutting and welding of thin metal sheets. The Q- switched laser is mainly used for crack-free cutting of hard and brittle material such as engineering ceramics.

The electrical resistance of AlN, an insulator with a typical electrical resistance greater than 10¹³ (Omega) - cm, was significantly reduce dafter irradiation from UV lasers. A typical value of a few hundreds (Omega) -cm was consistently achieved. The possible changes in the surface microstructure were investigated using a number of techniques, which included analysis of surface roughness, Raman spectroscopy and XPS. A thin aluminium layer is believed to have formed on the top surface that accounted for the shining metallic appearance after laser irradiation. The relationship between various laser parameters and the electrical conductivity were investigated. The etch rates of AlN with respective to laser power density are presented. The potential industrial application of this technology is discussed.

Laser cleaning is an effective cleaning method that can be widely used in microelectronic industry. Mechanisms of laser induced removal of particulate contaminants from solid substrates, such as Si wafer, are of great concern. The previous works on laser cleaning are mostly based on perfectly flat surface model, while few of them are objected to the influence of surface morphology. In the IC process, however, the Si surface morphology will change dramatically after few steps of processing, therefore its influence to laser cleaning efficiency is inevitable.In this experiment, the cleaning efficiencies of 2.5 and 1.0 micrometers spherical silica particles from Si with different surface morphologies are investigated. These surfaces were achieved by anisotropic etching of Si wafers in KOH solvent, with etching times raging form 1 minute to 30 minutes. Atomic force microscope observation showed the Rp-v roughness of thus-processed Si surfaces ranges from 1.6 nm to 70 nm, and rms roughness ranges from 0.1 nm to 9.0 nm. For both kinds of particles, the cleaning efficiencies decrease with increasing surface roughness. The possible reason is that the rough surface may buffer the sudden thermal expansion of the substrate, making the particles more difficult to be removed.

The manipulators of scanning tunneling microscope (STM) usually use 'long-travel' mechanically drived X-Y stages with piezoceramic actuators together with piezoceramic tubes. Magnetic- and electric Rheology manipulators combine the functions of the both drives in single unit and ensure the precision and the length of the travel L <EQ 200 mm along X, Y axes and L <EQ 400 mic along Z axe. Error of positioning of loop-contorlled MR- and ER drive may be expressed.

The present paper discusses the design and development of diode laser based sensor, which measures the snow particle size,the number of drifting snow particles passing per unit time through sampling volume and the speed of drifting snow particle. These factors, in turn determine the mass flux of drifting snow over the range of wind speeds. The design of sensor is based on interruption of the laser beam as the snow particle traverse through it. The extinction is detected by a suitable bi-element Pin photo detector. The sensor is designed for measuring snow particle size in the range of 100 micrometers to 2000 micrometers diameter and can count up to 100,000 particles per minute. The sensor is capable of measuring particle speed up to 50 meters per second. The sampling volume of sensor is selected in such a way that a single particle crosses the sampling volume at a time.

How to get a computerized program-controlled quasi-laser light source of 1.06 micrometers wavelength, with high speed response, stable and adjustable source power and high fidelity spectrum, has been studied in this paper. By using computer technology and time-delay method to simulate space distance, a series of problems about non-contact and undisintegration test of the while equipment, such as receiving sensitivity, range of blind area, accuracy of range finding, multi-target resolution, accuracy of selection and setting of laser range finder with 1.06 micrometers wavelength etc., has been solved. The characteristics of this light source is low cost, convenient to operate, and it has wide application prospect in manufacturing, debugging and fault repairing of laser range finder.

In this work, an optical system for digitizing 3D objects by using structured light is described. It is fast, contactless, highly accurate and it can work in strongly illuminated environments. An application for an industrial quality control set-up is presented, in which sand cores to be used in the car industry are automatically handled by a robot and analyzed by the 3D digitizer. After the analysis of each core presented by the robot, the digitizer sends an OK or KO instruction for the faultless or faulty piece to be placed by the robot in a different area. In order to perform all the calculations required for the analysis and for the hardware control, a specific software has been developed. A series of examples and result are shown with comments on the advantages of the method here described.

A mercury cadmium telluride (MCT) focal plane array has been sued to build a combined visible light and IR photoemission microscope with sensitivity up to 500 times better than conventional PEMs, which are based on either intensified or cooled CCDs. PEMs are widely used for integrated circuit failure analysis and in yield enhancement programs; they detect and identify failure sites by the low levels of light emitted from the semiconductor. An MCT based PEM operating in the wavelength range 800 nm to 2500 nm offers several advantages over systems operating in the visible part of the spectrum. Beyond 1000 nm, band gap emission is imaged directly from forward biased p-n junctions and this part of the spectrum includes the regions of most intense emission from avalanche breakdown and hot carrier defects. Beyond 1000 nm most silicon is effectively transparent and this offers significant advantages for backside failure analysis, especially for flip chip devices. Thermal emission is detected from ares approximately 1 degree C above ambient so failure mechanism not usually amenable to analysis by PEM can be located.

A new method of absolute measurement of photodetector quantum efficiency based on spontaneous parametric down- conversion (SPDC) biphoton field is discussed. The process of SPDC is studied theoretically. The single photon detection probability and two-photon coincidence probability are derived and the measurement principle of photodetectors is explained. An experimental system has been set up. The quantum efficiency of a photon-counting photomultiplier tube was measured, and the results were compared with that obtained using conventional method.

A portable phase shifting shearing TV-holography apparatus for non-destructive testing is presented in this paper. This apparatus has been utilized in the inspection of large area aluminum coated honeycomb structure of aeronautical composite for off-stick defect testing. The working principle and the configuration of the system are described. The structure will be detailed. Satisfactory result have been obtained with this system. Wrapped defect phase pattern will be shown.

Grating projection 3D profilometry has three major problems that have to be handled with great care. They are local shadows, phase discontinuities and surface isolations. Carrying no information, shadow areas give us no clue about the profile there. Phase discontinuities often baffle phase unwrappers because they may be generated for several reasons difficult to distinguish. Spatial phase unwrapping will inevitably fail if the object under teste have surface isolations. In this paper, a complementary grating projection profilometry is reported, which attempts to tackle the three aforementioned problems simultaneously. This technique involves projecting two grating patterns form both sides of the CCD camera. Phase unwrapping is carried out pixel by pixel using the two phase maps based on the excess fraction method, which is immune to phase discontinuities or surface isolations. Complementary projection makes sure that no area in the visible volume of CCD is devoid of fringe information, although in some cases a small area of the reconstructed profile is of low accuracy compared with others. The system calibration procedures and measurement results are presented in detail, and possible improvement is discussed.

A non-contact whole field vibration measuring method, which is based on speckle interferometry theory, is described in this paper. The whole field vibration model with amplitude ranging from zero to several microns can be obtained automatically. The frame update speed is 5 frames per second in our experimental. For demonstration, a round aluminum plate with 100 mm in diameter and 2 mm in thickness, of which the surrounding edge is bonded, is excited by PZT. The vibration model is measured. For the application, the preliminary result of the piezoelectric motor vibration model is described in this paper.

Phase unwrapping is an inevitable process in modern phase- evaluation based fringe analysis because the arctangent functions used in phase extraction only return phase modulo 2(pi) . In recent years, several temporal phase unwrapping methods have been proposed, which use a couple of phase maps with different sensitivities for the unique determination of the unwrapped phase on a pixel-by-pixel basis. We have found that, however, some of them are not effectively designed, probably due to the lack of proper philosophy for guidance. In this paper, we present a generalized mathematical excess fraction method, which is more compete and general in nature and can be used to re-interpret those temporal phase unwrapping algorithms in a unifying perspective. It is also demonstrated that more efficient and flexible algorithms can be designed based on the principle of the generalized excess fraction method.

A color-coded projection grating is used to provide means of measuring 3D surface profiles. In conventional 24 bits RGB model, each color has 256 gray levels, whereas we use only the levels of 0 and 255 to maximize the difference of gray levels. Thus there are eight colors which can be used to code the grating. They are white, red, green, blue, cyan, magenta, yellow, and black. In order to get a large space period grating, we code the grating on a specific order. If we use eight kinds of colors to code the grating, we can get 64 strips in one period. In this case the space period of the projection grating is large enough in the most of measurement of surface profiles. Only one image is needed in 3D measurement and so it is suitable for on-line inspection. In our system the measurement error is less than +/- 1.3 mm.

Abstract not available.

Modeling of generic scanned imaging systems was described in previous papers. The spatial, temporal and transform domain analysis was performed based on these models. But, the response function of detectors was variation-separable. This case is unsuitable for thermal imaging systems, which use signal-processing-in-the-element (SPRITE) detectors, because of the variation-inseparable response function of the SPITE detector. In this paper, the improved model of scanned thermal imaging system of SPRITE detector is described. Based on this model, the system analysis is performed on temporal-spatial domain, and also performed on temporal- spatial-frequency domain. Furthermore, the modulation transfer function (MTF) expression of SPRITE detectors is described. With that, it is convenient to evaluate the dynamic imaging capability of scanned systems, and image transfer characteristics of SPRITE detectors.

Abstract not available.

Development of high power solid state laser makes us notice that thermal conductivity and heat expansion coefficient of laser crystal are not constant as temperature is increased. When we assume the heat density in the laser crystal is uniform, the temperature and stress profiles are on- quadratic, and the temperature and stress in laser crystal are higher than those we treat thermal conductivity and heat expansion coefficient as constants. Actually, it is difficult to achieve uniform heat density. We apply end- pumping geometry to side-pumping geometry, and assume the heat density in any cross section of the laser crystal rod is Gaussian profile. Then optical to optical efficiency will be very high due to excellent overlap between optical pumping volume and mode volume. We simulated the temperature and stress profiles in this situation using finite element analysis.

Pulsed laser generated carbon plasma combined with a nitrogen ion source has been used to synthesize carbon nitride thin films. This synthesis method has both advantages of pulsed laser deposition (PLD) and ion implantation. The average ion beam current, the beam voltage, the laser pulse energy, and substrate temperature can be controlled systematically. STM has been sued to study the surface properties. The (dI/dV)/(I/V) values have been calculated to study the local density of states density of states on the film surface. Experiment results have been analyzed by Raman spectra to see the influence of the different ion beam voltages. Thin films CN_x with nitrogen content of 32 percent have been investigated by x- ray photoelectron spectroscopy. The result can reveal the formation of different bonds. Fourier transform IR was also used to study the bonding of films. The hardness of the synthesized thin film was analyzed be a nanoindenter. The result shows that the hardness of carbon nitride is quite high.

We report on the development of a dynamical model for the passive Q-switching of a diode-pumped Nd:YVO₄ laser using GaAs as the saturable absorber and output coupler. A complete set of rate equations are derived, taking into account the two-photon absorption and free-carrier absorption of GaAs. By solving the rate equations numerically under different conditions, it is demonstrated that the output pulse width can be predicted theoretically, and the results obtained show good agreement with hose obtained experimentally.

Conventional IR optical systems with high magnification and switchable FOBs suffer form strong unwanted Narcissus effect. This is mainly caused by retro-reflections from the objective lens back to the detector plane. In this project, a new dual aperture optical configuration has been developed to reduce substantially the Narcissus effect while maintaining good optical performance. A design example is presented in this paper. The relative Narcissus Induced Temperature is reduced from about 1.4 degree C to about 0.1 degree C, thus enhancing the detection range of the IR system.

Loss of image information is a profound problem with conventional IR cameras using focal plane array (FPA) technology. This is due to the limitation of semiconductor fabrication technology which results in ineffective are between the cells of the FPA detector. In this project, dual axis microscanners have been developed to capture the undetected image, as a result, improving the overall image resolution of the IR cameras.

Micro-machining techniques using pulsed lasers are currently being applied world-wise in many diverse industrial application areas including biomedical devices, printers, flat-panel displays, semiconductors devices and telecommunication systems. In particular, the use of excimer lasers has been at the forefront of the new developments in the manufacture of complex micro-structures for the production of micro-optical-electro-mechanical-systems units such as nozzles, optical devices and sensors. This paper reviews the fundamentals of excimer laser micromachining techniques and details recent developments which have enhanced the capabilities of these approaches. Application areas where these techniques are of interest are highlighted.

The 'optoelectronics industry' is a collection of six or more distinct industries that all depend on OE technology. The major markets are in communication, imaging, storage and displays. This paper gives a brief overview of the anticipated paradigm shifts, the potential markets and the promising new technologies in various OE markets.

The developing of vertical-cavity surface-emitting lasers (VCSELs) has led to new types of low power, high efficiency light sources for data communication. The small size, low power, and surface-normal emission of VCSELs has enabled relatively dense 2D arrays for highly parallel data communication and optical signal processing. In this paper we examine the issues of device scaling on VCSEL performance. We look specifically at what benefits may be derived from continued scaling of the active volume down to minimum sized dimensions, and what device schemes may be required to obtain the scaling. Laser rate equations are used to show that when the VCSEL mode volume is reduced to wavelength cubed dimensions, a significant improvement in modulation speed is predicted based on the radiative lifetime change due to the Purcell effect. However, several parasitic effects must be controlled in order to realize these benefits. Most important are control of the otpical loss due to diffraction or scattering, and control of the electronic losses due to carrier diffusion and surface effects. Novel optical confinement schemes based on oxide- apertures, photonic band gaps, and/or closely coupled 2D arrays may be useful for controlling optical loss, while self-assembled quantum dots are attractive for controlling electronic diffusion to dimensions within the minimum optical mode volume.

A microscope many-body theory for the nonlinear optical response of semiconductors is reviewed. The importance of Coulomb interaction induced carrier correlations is demonstrated in excitonic pump-probe spectra. The influence of excitonic and biexcitonic contributions to coherent pump- induced absorption changes at the exciton frequency are discussed. Absorption changes induced by incoherent exciton and unbound electron-hole populations are studied.

This paper discusses the role and impact of advancements in Photonics Technology on the performance enhancement of guided missile weapon systems with specific reference to the development of Indian guided missiles program. India is emerging as a technologically strong nation with core competence in Space, Missile and Nuclear technologies, advanced computing including supercomputers and software. Based on the realization of the fact that high technology strength is the key to economic prosperity and military strength, India is progressing several high technology areas that help in attaining the global competitiveness. Photonics is identified as one of the important areas in this direction and hence high priority has been accorded for R and D in Photonics. This paper reviews the current trends and developments in missile technology and highlights some of the important developments in Photonics that have a force multiplying effect on the performance enhancement of guided missile systems.