A solid state (Charge Coupled Device) imaging system is described which satisfies the requirement for multispectral, high resolution, real time imagery. The system, using an earth resources survey satellite as its platform is configured to yield a 10 meter ground resolution with a 50 kilometer swath width at approximately 1000 km altitude. Four spectral bands ranging from 0.5 to 1.1 μm have been selected and are implemented by optically butting three 1728 pixel linear arrays (5184 pixel per band) on appropriate beam splitting prisms. The device employed, the Fairchild CCD 121H, shown in Figure 1, is a monolithic self-scanned image sensor utilizing two phase, buried n-channel CCD technology. The device has an element-to-element pitch of 13 μm (approximately 2000 pixel inch) and has been demonstrated to have a wide dynamic range (2500:1), Figure 2, low noise equivalent exposure and dimensionally precise photosite spacing. Consideration of focal plane design, geometric accuracy, image registration, temperature control, optical design, and noise figures are discussed. Particular emphasis has been placed on the unique properties of CCD detectors which allow for specialized post processing of the video for dealing with low contract scenarios. The paper concludes with new trends in specialized time delay and integration (TDI) mode imaging systems now under study and development at Fairchild.

Buried channel charge coupled device TV technology has had an impact on the DOD sensor community to date, and with the imminent arrival of the CCD camera modules (resulting from the NAVE LEX sponsored CCD Modular Camera Program) it is anticipated that this trend will greatly accelerate. The characteristics of a family of versatile electro-optical building blocks satisfying a wide environmental range is de-scribed. The modules discussed include lens/ALC assemblies, several high performance thermo-electric cooled hermetic CCD device enclosures (typically 0.7 cubic inches), various logic, video processor, power supply, high efficiency temperature control circuits mounted on conventional printed circuit cards employing customized hybrid/MSI components. A unique module which allows direct coupling of image intensifiers to CCD arrays without the use of a vacuum enclosure is described. It is seen that appropriate selection of modules coupled with customized packaging/interconnect hardware presents attractive low cost high reliability alternatives to the present design/procurement techniques now associated with DOD-type TV cameras. Several applications of this technique are discussed including a current airborne cockpit television system, a TV training/scoring system used with the TOW missile program and an E/O missile guidance CCD seeker head.

The Thematic Mapper (with its 30 m ground footprint in five-spectral bands from 0.4 μm to 2.0 μm and 120 m GFT in a 10.5 μm to 12.5 μm spectral band) represents the next generation sensor system for application to earth resource survey. The Thematic Mapper (TM) uses a 56 cm x 42 cm oscillating mirror to scan the scene, and is designed to provide accurate radiometric measurements. Currently, in the visible focal plane the discrete detectors must provide 80% quantum efficiency, nominally 100 electrons noise, less than 5% ripple in the spectral response, and 0.5% signal crosstalk to meet system requirements. This focal plane uses complex hybrid assembly techniques to interface silicon photodiodes to JFET preamplifiers. This complexity can be ameliorated by using a new approach in signal pro-cessing which takes advantage of the properties of charge-coupled devices (CCD). A 20-channel time-delay-and-integration (TDI) CCD with nine stages of integration per channel has been built for a TM application. By going to a CCD array which operates in a TDI mode, over 700 individual Op Amps can be replaced with only 48 Op Amps. Smooth spectral response and 70% quantum efficiency have been provided by using doped tin oxide gates over the imaging region. The 20 x 9 TDI device when operated with all 9 integration stages, ,exceeded SNR requirements by a factor of 2. The crosstalk performance is controlled by providing high charge transfer efficiency using a buried channel CCD. The TDI device has demonstrated charge integration for both forward and reverse scans of the oscillating mirror, and a form of exposure control is provided by integrating over 3, 6, or all 9 stages in either direction of scan.

The Space Telescope (ST) will carry five astronomical instruments into Earth orbit in late 1983. The performance of each of these instruments is critically dependent on the detectors. The detectors studied during the planning stages for the ST and those to be used in the four US instruments for the first flight are described.

Work has been done with extending the useful imaging and detection range of CCD's and Solid State Arrays. This was accomplished both through direct optical coupling and bonding of image intensifiers to the arrays and using the arrays in the electron bombarded mode. The bonding of the intensifier is accomplished by matching the fiber optic output window of the image intensifier to the geometry of the array and bonding this special tube directly to the surface of the CCD. It has been shown that the useful range of a CCD may be extended four orders of magnitude using these techniques in coupling a microchannel plate image intensifier to the CCD array. The performance shows full image detection, not threshold imaging, down to 10^-5 ft-cd input with the array running at standard TV scan rates. This has been accomplished in a package 2.0 inches in diameter and less than 1.5 inches long. Other tubes have been made with arrays mounted inside the tube envelope and using a photocathode to image the photoelectrons on the array which is operated in the electron bombarded mode. All of this work was done with presently available CCD,CID and photodiode arrays made by Reticon, Fairchild and General Electric.

Using CCD and CID image sensors, the array of detector elements performs a spatial sampling, which sets a maximum limit (Nyquist frequency) on the spatial resolution. In some sensors the MTF is high at and beyond the Nyquist frequency. By moving the sensor relative to the scene it is possible to obtain samples in between the stationary sampling positions. Thereby, the maximum spatial frequency limit is increased. This paper describes measurements with a CCD image sensor using this dynamic sampling effect. Resolution up to 3.5 times the Nyquist limit is shown. A theoretical calculation of expected obtainable MTF's for different sets of parameters is presented. This can be used to select parameters for best possible result when using the dynamic sampling effect.

Astronomical imaging demands a great deal from a detector. Recently a number of systems have been developed which have increased the efficiency of telescope usage by more than a factor of ten. A number of the newer detectors are described with reference to the special characteristics required for astronomical work. It is expected that the trend toward the use of efficient detectors will increase as the readily available detectors continue to improve in performance and ease of operation.

M.I.T. Lincoln Laboratory is engaged in supporting the Electronic Systems Division (ESD) of the Air Force Systems Command (AFSC) in developing the Ground-based Electro-Optical Deep Space Surveillance (GEODSS) system. As a part of this program, low-light-level, large-format, silicon-diode-array vidicon sensors capable of photon-noise-limited operation under typical dark-sky conditions have been developed and tested both in the Laboratory and at the Experimental Test Site (ETS), White Sands Missile Range, New Mexico. This paper begins with descriptions of the GEODSS system, and ETS's role within that system. This is followed by a brief history of the design and development of the sensors, a general discussion of the theory of operation, a description of point-source experiments, and the presentation of an empirical model which describes the detection capability achieved in the field with the ETS electro-optical sensors. In the final sections of the paper, the problem of the detection of satellites by reflected sunlight is described and the highlights of data collected at the ETS are presented.

Optical design and engineering of the electro-optical (E-0) system used for automatic tracking and laser designating targets from high-performance aircraft require consideration of many aspects of the total system; for example, large look-back capability, maximum aperture, accurate boresight, and high transmission. First and second generation E-0 pods have been designed and manufactured using a multifunction objective lens that combines apertures for a dual field of view (FOV)/dual wavelength camera system, laser designator, laser ranger, and laser spot tracker. A diffraction-limited telephoto objective lens with an FOV capability of 1, 1.5, and 6 degrees is the heart of the optical system. The design provides good image quality while meet-ing the needs of the laser functions and allowing ease of maintenance through modular construction. The engineering of the optical bed for mounting the components in the pod in a dynamic environment required detailed analysis, using both optical deflection tolerances and structural characteristics. A mathematical model of the optical bed provided a means for determining stiffness requirements to meet the needs of imagery and boresight. The silicon target vidicon sensor allows a unique capability for automatic, in-flight boresight.

This paper addresses the first applications of low light level television to Army night training. All the progress made from the first application up to the present man-portable systems being fielded at Fort Hood, Texas, will be discussed.

The new SEC image camera tube is designed for astronomical application. Its large target allows a wide viewing, angle with excellent resolution and little distortion, as the tube is magnetically focussed. The target is able to store information over several days and with proper cooling, integration of weak light signals is possible over several hours. A. sequential writing - reading, slow scan mode is suggested for most effective application. The window is transmissive far into the vacuum UV-spectrum. Zooming with a fourfold magnification has been successfully demonstrated employing a magnetic lens in front of the image section. The tube construction is ruggedized to withstand the shock and vibration requirements of rocket launch.

Two general techniques may be used for whole image detection by electronic means in the extreme ultraviolet (XUV). 1) The XUV image is converted to a visible image for further processing, and 2) the XUV image is detected via the photoelectrons it ejects from a photocathode. The first technique involves the use of a phosphor either as a conversion layer to be excited directly by the XUV photons, or as a luminescent detector of photoelectrons created by the XUV photons. The second technique may require that the number of photoelectrons be amplified while preserving the same spatial coordinates as the impinging XUV protons. After amplification, the spatial coordinates of the amplified photoelectrons can be determined using different electronic techniques. Alternatively the second technique makes use of electronic imaging systems wherein the photoelectrons created by an XUV image on a photocathode are focussed onto nuclear track emulsion to form a photographic record of the image. Representative examples of each type of imaging system will be discussed.

Details of an advanced electronics imaging system which has been applied to field neutron radiography are presented in this paper. Heretofore, many applications of neutron radiography have not been utilized due to system mobility and long exposure times. A modified image intensifier was used with a scan conversion memory and mobile neutron radiography system to obtain neutron radiographs on a television monitor in .5 to 10 minutes. The electronic imaging system consists of a phosphor screen coupled to a light amplifier by a Bouwers' concentric mirror system with an aperature of GRA 1:0.65. The image is transferred from the light amplifier through relay optics to an image isocon television camera. A standard EIA 525 line system is used to interface easily with output devices such as frame integrator, video tape recorder, kinescope, and monitor. Some application areas of neutron radiographic systems for quality control are discussed, i.e. 1. Aircraft maintenance for detecting corrosion. 2. Ammunition inspection: Charge gradients. 3. Biomedical for pathological investigation of bone tumors. Real-time imaging is tied to reactors, accelerators, and large Californium-252 sources. Field applications dictate small Californium-252 sources for portability. When small sources are used, a frame integrator is added to the system which enables exposures to be made from seconds to ten minutes.

A fully portable, small-format X-ray imaging system with the acronym Lixiscope (Low Intensity X-ray Imaging Scope) is described. In the prototype, which has been built to demonstrate the feasibility of the Lixiscope concept, only well-developed and available components have been used. We discuss the principles of operation of the device, some of its performance characteristics as well as possible dental, medical and industrial applications.

We have evaluated the suitability of a CCD for use as a soft X-ray (E < 2 keV) image detector for astronomical and laboratory applications. The sensitivity of a currently available CCD to soft X-ray radiation has been measured. It was found to be comparable to that of other presently available X-ray image detectors. Back-illuminated CCDs which will be available soon offer significantly greater sensitivity, especially at longer X-ray wavelengths. Theoretical X-ray spectra of hot optically thin plasma sources such as those found in the solar corona or supernova remnants have been convolved with the response characteristics of the various CCDs, and minimum detectable fluxes have been determined as a function of plasma temperature. When operated at very low temperatures with optimal noise adjustment, the CCD may be used as an array of single X-ray photon detectors of excellent spectral and reasonable spatial resolution.

A new X-ray system developed by Reifsnider and Green is used in this work for cine recording of Laue transmission X-ray diffraction patterns. This system incorporated a cascaded image intensifying tube and permits direct viewing and recording of Laue transmission X-ray diffraction patterns produced on a fluorescent screen, with exposure time as short as 1/220 sec. The tube used was RCA type C70021A, three stage, cascaded and magnetically focused. It was surrounded by a water cooled magnetic coil which supplies a uniform axial field of about 300G. The tube had 1:1 magnification and the diameter of both input and output screens was 3.8 cm. The fluorescent screen was positioned at a distance of 3 cm on the side of the specimen mounted on Instron testing machine opposite the X-ray source. A Super-Farron, f:0.87, 72 mm, wide angle, coupling lens corrected for 4 to 1 demagnification demagnified Laue transmission X-ray diffraction pattern of about 15.4 cm size from the fluorescent screen and projected it on to the 3.8 cm. photocathode of the image intensifying tube. Cine recording of changing Laue patterns in non-stop tensile testing of aluminum single crystals up to fracture revealed details of lattice rotation hitherto unnoticed in conventional deform, stop and shoot the picture tests.

The Hanford Engineering Development Laboratory (HEDL), operated by the Westinghouse Hanford Company, is developing automated equipment for fabrication and inspection of nuclear reactor fuels. One inspection process that has been evaluated is automatic surface flaw inspection of nuclear fuel pellets. The inspection technique involves projecting a well-defined spot of light onto the surface of a rotating pellet and collecting the light specularly reflected from the pellet's surface. The data form a binary description of the surface topography, which is then processed to identify and quantify flaw attributes before accept/reject decisions are made. The inspection apparatus is designed to operate at a rate of three pellets per second. A unique flaw interpretation algorithm is used to evaluate surface acceptability. The size and shape of a flaw is characterized by its area and by its area-to-perimeter ratio.

The ThermAtrace, an innovative infrared scanning instrument was introduced in early 1977 and described in a paper presented at the SPIE 21st International Symposium in August, 1977. Since then the instrument has gained wide acceptance, particularly in energy related applications. This paper reviews the instrument's operating principles, illustrates a wide range of applications experienced over the past year and describes the improvements and refinements made to the instrument as a result of field experience.

A mathematical representation of the Manportable Modular FLIR resolution sensitivity has been derived from well known and accepted principles. The model incorporates the nonlinear operator/system interface in both the visual perception and the black level control optimization. Measured data from AN/TAS-4 (TOW night sight) and Martin Marietta's Combat Vehicle Night Sight provides a preliminary validation of the model.

A new method for determining the time distribution of blood-flow within a vessel using x-ray imaging is presented. The method has been validated by both stationary and pulsatile flow experiments. The method is capable of determining average flow values under conditions of high pulsatile flow. The application of this method to cine-recorded data of aortic blood flow in dogs is in good agreement with the known shape of the aortic flow distribution. An application of this method to evaluate aortic regurgitation is shown.

To view and align Shiva laser targets, two new telemicroscopic instruments integral with TV camera and HeNe laser illuminator have been designed. The common requirement of both instruments is the capability of imaging two objects of different sizes on a TV screen: the large surrogate target (5 mm diameter) and the laser fusion target (0.250 mm diameter) with the same resolution (better than 7 μm). Both instruments have an optical relay which images the targets on a fixed reference reticle; the object is to center each target on the reticle. One of the instruments reimages the reticle plane onto the TV detector using a zoom arrangement. This instrument translates the TV,camera-zoom assembly in three axes and is thereby capable of exploring an object-space volume of 1 cm³. In the other instrument, the reticle plane is reimaged by a zoom lens and this enlarged image is relayed to the TV detector by a cluster of five lenses. Four lateral lenses image the periphery of the surrogate target and the reticle for coincidence. The central objective images the center of the reticle and the fusion target when it is centered.

Computerized systems for industrial inspection of simple forms or limited variables have been wide spread. However, the automated inspection of complex patterns is still limited. This paper describes an in-process inspection system for the thick film screen printing process where high density complex signal patterns are printed on ceramic substrate. The cost of the process necessitates a high production yield. The quality requirement is stringent, and the alternative, manual inspection, is both inefficient and ineffective. Using existing digitizing tube technology coupled with a mini computer, the system scans and detects defects based on programmable parameters. The computer controlled stage transport allows full coverage of the object under inspection. An algorithm is developed to automatically align the object and the master images. The system represents a successful application of imaging technolopy to industrial inspection of complex and noisy pat-terns. It is fully automated and human engineered such that an operator with a minimum of skills and train-ing can operate a cluster of up to three systems, The high depree of confidence in its inspection efficiency and the throughput rate render the system a viable industrial inspection tool.

A systems approach to established analytical spectroscopic instrumentation is presented, incorporating modern photo-optical display components in a unique array. The resulting instrument has applications relevant to the state of the art in microprocessor controlled medical spectroscopy and toward the future of computer controlled analytical optical techniques. This novel instrumentation design approach adds new dimension to Beer's law by allowing an automatic ranging feature, requiring no chemical manipulation of the samples to be analyzed. This instrument ushers in a new era in flexibility and accuracy now possible in spectrophotometric diagnostic techniques.