The key high-speed characteristics of specialty ITT streak-tubes, photomultiplier tubes (PMTs), gated image tubes, and vacuum photodiodes are discussed. Type #F4157 and #F4157U streak-tubes are operable in the extraction mode with 20 ps FWHM resolution and in the normal swept-imaging mode with 100 ps FWHM resolution, and their spectral sensitivities are above 10 mA/W for the 435-870 nm and 325-830 nm wavelength ranges, respectively. Microchannel plate (MCP) photomultiplier tubes (MPMTs) are being made with single anodes, multiple anodes, and resistive anodes, and they have speeds-of-response which range from 460 ps FWHM for the #F4129 in an #F4545 coaxial output holder, to 0.5-1.0 MHz maximum pulserate for the #F4146M photon-counting position sensing PMT (PSP). Gated MCP image tubes (CITs) have shutter periods down to 1 ns or less for specially designed versions. The 18 mm and 25 mm active diameter MPMTs and CITs are available with either conventional or GaAs photocathodes. The vacuum photodiodes are capable of producing output rise-and-fall times less than 100 ps.
Many years of research in Philips laboratories have enabled the development of a second generation image intensifier, the XX 1610, with characteristics close to an image intensifier of the third generation. In this paper, we will describe the various technical characteristics which determine the excellent performance of the XX 1610, such as photocathode sensitivity, signal to noise ratio, modulation transfer function and mean time to failure. We have made a comparison between image intensifiers of the second and third generation and the XX 1610. It is shown that the XX 1610 nearly matches the performance of a third generation image intensifier in term of equipment performance. When economic factors are also taken into account, the XX 1610 can be considered as a very competitive image intensifier.
This paper describes the gating properties of some first and second generation image intensifier tubes and the application of these tubes as preamplifiers for solid state image sensors. Results are given of the performance as a function of the gate pulse width of a single stage first generation inverter tube, a second generation wafer tube and a hybrid tube coupled to a solid state image sensor.
It is critically important to bias resistive-anode MCP photomultiplier tubes with the correct potentials in order to achieve optimum resolution. For the ITT version, type #F4146M, of this type of photon-counting imaging detector the optimum bias potentials are as follows: cathode-to-VMCP, 700 V; VMCP-to-ZMCP, -150 V; ZMCP to-anode, 100 V. The potentials applied across the VMCP and ZMCP for optimum gain and resolution are approximately 1800 V and 2100 V, respectively. Investigations of the tube and position computer have been undertaken in an attempt to significantly improve the resolution of the entire camera system. It appears that an improved understanding of the detailed signal flow through the tube will lead to ways to achieve higher resolution in this part of the camera system. Preliminary results of the modeling being used for the tube are presented. Forward and reverse bias conditions between the VMCP and ZMCP produce fundamentally different electron landing patterns on the ZMCP input face. These landing patterns appear to be key ones to study in terms of the possible significant resolution tradeoffs with MCP bias angle, gain, V-ZMCP bias potential, etc. The resolution effects of the cathode-to-VMCP and ZMCP-to-anode proximity focused sections appear to be straightforward: increased electric field strengths and reduced spacings reduce the resolution limiting effects in these sections.
High speed active gated image intensifier tubes can be used for vision through sea water and for target detection. The quality, range and field of view of the imaging system and the efficiency of the target detection is determined by the radiant power of the laser, water attenuation and image intensifier system parameters. This paper discusses the relationships between the imaging systems parameters and presents qualitative illustrations for systems applications.
The classical, idealized spread functions are defined as the probability density functions. In the case of image intensifier such a concept disregards the fact that in any real electron-optical system, the PSF is detected not as a density of probability but as an average value of this function in a neighborhood of a given point. This may be connected with the structure of the microchannel plate or with the granulation of the phosphor on the screen. Similarly, the use of the ray-tracing method and the endpoint counting procedure for the numerical calculation of the spread functions, results in the evaluation of the locally averaged values. According to that, the aim of this paper is introducing the new generalized formulas for real spread functions. This paper contains both the analytical and numerical formulaS for the spread functions in the general case of the aberrated spot diagram. A new concept of the three-dimensional (3-D) point spread function (PSF) is presented using the same mathematical formalism. The physical illustration of this concept is shown with reference to the statistical-image-surface (SIS). The proposed formulas may be also simply used as a basis for the calculation of the spread functions for the case of the polychromatic illumination.
A modular approach to design has contributed greatly to the success of the family of machine vision video equipment produced by EG&G Reticon during the past several years. Internal modularity allows high-performance area (matrix) and line scan cameras to be assembled with two or three electronic subassemblies with very low labor costs, and permits camera control and interface circuitry to be realized by assemblages of various modules suiting the needs of specific applications. Product modularity benefits equipment users in several ways. Modular matrix and line scan cameras are available in identical enclosures (Fig. 1), which allows enclosure components to be purchased in volume for economies of scale and allows field replacement or exchange of cameras within a customer-designed system to be easily accomplished. The cameras are optically aligned (boresighted) at final test; modularity permits optical adjustments to be made with the same precise test equipment for all camera varieties. The modular cameras contain two, or sometimes three, hybrid microelectronic packages (Fig. 2). These rugged and reliable "submodules" perform all of the electronic operations internal to the camera except for the job of image acquisition performed by the monolithic image sensor. Heat produced by electrical power dissipation in the electronic modules is conducted through low resistance paths to the camera case by the metal plates, which results in a thermally efficient and environmentally tolerant camera with low manufacturing costs. A modular approach has also been followed in design of the camera control, video processor, and computer interface accessory called the Formatter (Fig. 3). This unit can be attached directly onto either a line scan or matrix modular camera to form a self-contained units, or connected via a cable to retain the advantages inherent to a small, light weight, and rugged image sensing component. Available modules permit the bus-structured Formatter to be configured as required by a specific camera application. Modular line and matrix scan cameras incorporating sensors with fiber optic faceplates (Fig 4) are also available. These units retain the advantages of interchangeability, simple construction, ruggedness, and optical precision offered by the more common lens input units. Fiber optic faceplate cameras are used for a wide variety of applications. A common usage involves mating of the Reticon-supplied camera to a customer-supplied intensifier tube for low light level and/or short exposure time situations.
This paper presents pertinent information required in the specification of the components for an intensified solid state television camera. Design criteria for operating wavelength, input light levels, gating requirements, coupling techniques, and camera type will be discussed. Interaction of the various elements of an intensified television camera will be addressed as they relate to overall camera performance levels and equations for calculating certain performance characteristics will be provided.
This article discusses a number of the major problems confronting the devOopment of present day semiconducting IR focal plane detectors for large array space based applications, shows that an entirely new detector technology based on superconductivity may circumvent many of these difficulties, provides detailed data on the characteristics of these devices and outlines the development program underway to exploit this new technology.
The Heimann company has developed a 1" mixed field saticon (magnetic focus-electrostatic deflection) with diode gun. This new pick-up tube was specifically developed for High Definition Television (HDTV). The key requirements for an HDTV system piick-up tube are: o Very high resolution o Very high signal to noise ratio o Very low lag o Very low stray capacitance The improvements have been achieved through the use of an Se-As-Tle amorphous photocon-ductive target which does not limit resolution due to vitreous stru ture and high resistivity. Also, a diode gun is used which provides a nearly parallel, 1 w temperature electron beam which with electrostatic deflection guarantees optimal linearity. Signal to noise ratio is significantly improved as stray capacity is reduced, and the saticon photoconductive target with diode gun allows signal currents of 3 micro amps or more, his tube has been successfully demonstrated, both in HDTV and Medical X-Ray Imaging Systems as well.
We are developing an intensified charge-coupled device (ICCD) detector system, based on the incorporation of a thinned backside-illuminated CCD as the anode of a Hubble Space Telescope design Digicon tube, for particular application to astronomical observations with stringent requirements for accuracy, rapid temporal response, low background, and high two-dimensional resolution. In this paper, images are presented which demonstrate the capability this system provides in achieving sub-CCD-cell resolution, representing a substantial increase in this attribute. These results also indicate that the amount of this increase is at present constrained by the limited extent of the spreading of photoelectron-generated charge evident in the particular thinned CCD used here, and that further increases in resolution remain possible with the use of thicker chips. In connection with this, the potential benefits of magnetic deflection substepping in ensuring excellent uniformity of elemental response in the overall sensor system are shown dramatically in this study. Additionally, we present preliminary results from the fabrication and testing of mesh photocathodes suitable for inclusion in such a system, which may be applied to extend wavelength coverage into the extreme ultraviolet, and from the successful processing and operation of a sealed CCD-Digicon tube.
This paper describes a high resolution x-ray imaging device, which is under development at the University of Arizona. It is sponsored by NIH for application in coronary angiography, but has also application in other x-ray imaging fields requi ing high spatial resolution, such as mammography and nondestructive tasting. It consists of a 6" diameter external modular sensor, coupled fiber optically to the input of a 6" proximity focussed image intensifier. The intensifier's output is coupled via 6 fiber optic tapers to 6 CCD's for readout. The tapers are joined at the large end to form a 6" by 6" coplanar fiber optic taper assembly. The electronics is designed to form a composite image out of the 6 individual images provided by the 6 CCD's and display the image in full resolution (1152 x 1152) on a high resolution physicians review console. The paper discusses the design considerations, the features, the major problems and some preliminary results.
The High Output Technology Mlcrochannel Plate (MCP) is a state-of-art electron multiplier designed specifically for applications requiring sustained high output currents and extended dynamic range. Increases in dynamic range of up to 150X have been demonstrated without thermal runaway problems.
A preconditioning scheme for the stabilization of microchannel plate (MCP) Z stacks has been developed. Vacuum baking of MCP Z stacks is shown to have little effect on the gain and pulse height distribution characteristics, but tends to increase the background event rate. The major outgassing components during baking are found to be H2, N2, H2O, and CO2. The MCP stack resistance is found to decrease as the temperature rises, and the temperature coefficient has been determined. Burn-in of MCP stacks is shown to cause a 3x to 10x decrease in gain and also results in minimization of the background event rate. The major outgassing components during burn-in are found to be H2, N2, and CO2. Stabilization of the MCP stacks has been achieved when 0.06 to 0.08 Coulomb cm-2 have been extracted from the MCP stack output during burn-in.
A new type of Microchannel Plate (MCP) is described which has very small channels. MCPs with channels of both 6 and 4 micron pores are characterized. Single and multiple stage detectors were evaluated for rise-time, pulse width, spatial resolution, gain and pulse height resolution. A performance comparison with current state-of-the-art devices is made.
Performance data of curved channel microchannel MCP's from the last 3 years is presented. The parameters affecting curved channel MCP performance are discussed and graphs of gain and % full width at half maximum (%fwhm) are presented as a function of pore size and aspect ratio (L/D). Data for kun pore curved channel MCP's is presented. Performance of curved channel MCP's as a function of glass type is also discussed. The fabrication process of curved channel MCP's is discussed briefly.
A new type of microchannel plate (MCP) is described which possesses extremely low intrinsic background noise. This property was achieved by fabricating the MCP from a newly developed glass formulation which was designed to be essentially free of radioisotopes. New measurements are presented on recently fabricated low noise MCPs which show that these plates yield background count rates several times lower than the quietest MCPs available. The results of radioisotope assays performed on the first two groups of prototype low noise MCPs are reported; these assays suggest that even further reductions in noise can be achieved. Improvements made possible in the sensitivity of MCP detectors are discussed.
The design of the Quartz Envelope Heater(QEH) has progressed dramatically. We originally developed the QEH for application in MOCVD and other gas phase epitaxial technology. The present design expands its capabilities to include ultra high vacuum applications and possibly to applications in which other ceramics or refractory metals are substituted for the outer quartz envelope. The heater consists of an evacuated quartz outer envelope which supports the sample and an internal resistance heater, which is below the sample and up against the, upper, inner surface of the quartz envelope. The configuration of the QEH enables the construction of a high temperature resistance heater with an inert outer surface exposed to the process environment and functional parts which are shielded from that environment. We include a detailed description of several older models along with a description the the newest version of the QEH to give insight into its design.
This spectrophotometer is being used to measure the cathode photoresponse and quantum efficiency of image tubes in the UV to near IR region (from 200 nm to 900 nm), with an external lock-in amplifier synchronized to the Cary's internal optical chopper. Good day-to-day stability has been routinely verified by using an image tube calibrated by a photometrics laboratory. Fully automatic operation is achieved via a Varian personal computer and IEEE-488 communication. Hard copy printout is both numerical and graphical.