Recently, considerable interest has been expressed in the use of radar to detect underground targets both small (e.g., antipersonnel mines) and large (e.g., buried vehicles). Particular interest has been directed at airborne SAR for this purpose. Several important issues requiring study include the scattering signature of objects buried in soil media, the attenuation and scattering of radar energy in inhomogeneous soils, and the impact of clutter (and particularly the impact of surface clutter layover) on subsurface target detection and recognition. To address these issues, a radar ground penetration experiment was conducted in the desert near Yuma, AZ from June 4 to 15, 1993. In this experiment a number of large and small targets of various shapes were buried at depths up to 3 m, and data was collected using several air- and ground-based radars using both real and synthetic aperture data processing. The variety of radars available covered the range from 20 to 1500 MHz. The data collected was calibrated with sufficient accuracy to permit the measurement of in situ radar signatures, allowing the calculation of ground penetration losses. Data from this test have been analyzed to develop a phenomenological understanding of soil penetration losses and clutter backscattering, and to investigate the characteristic signatures of specific buried targets. These data are compared to laboratory soil measurements and modeling studies. This paper will describe the experiment, sensors, sample radar measurements and some of the results of the data analysis.

CARABAS, an acronym for `coherent all radio band sensing,' is an airborne, horizontal-polarization SAR operating across the frequency band 20 to 90 MHz, conceived, designed and built by FOA in Sweden. The original motivation for designing such a low frequency system was that a large relative or fractional bandwidth could be achieved at low frequencies. For reasons to be explained, a large fractional bandwidth was considered to be of potential benefit for radar detection in severe clutter environments. A feasibility study of a short wave ultra-wideband radar started at FOA in 1985. Actual construction of the CARABAS system commenced 1987, aircraft integration took place during 1991 and the first radar tests were conducted in early 1992. From the fall of 1992 onwards, field campaigns and evaluation studies have been conducted as a joint effort between FOA and MIT Lincoln Laboratory in the US. This article will focus on experiences concerning foliage penetration with the system. First we touch upon the CARABAS system characteristics, outline the arguments behind a large fractional bandwidth VHF-band SAR approach to foliage penetration, and finally present some early experimental results. We refer to other papers for a fuller explanation of the system, for more details of image calibration, and for results concerning underground imaging.

For the past four years Airborne Environmental Surveys, a division of Era Aviation, Inc., has used unique and patented airborne frequency modulated, continuous wave radars and processes for detection and mapping subsurface phenomena. Primary application has focused on the detection of manmade objects in landfills, hazardous waste sites (some of which contain unexploded ordnance), and subsurface plumes of refined free- floating hydrocarbons. Recently, MSB Technologies, Inc. has developed a form of synthetic aperture radar processing, called GPSAR, that is tailored especially for the AES radars. Used as an adjunct to more conventional airborne ground-penetrating radar data processing techniques, GPSAR takes advantage of the radars' coherent transmission and produces imagery that is better focused and more accurate in determining an object's range and true depth. This paper describes the iterative stages of data processing and analysis used with the radars and shows the added advantages that GPSAR processing offers.

LLNL is developing an ultra-wideband, side-looking, ground- penetrating impulse radar system that can be mounted on an airborne platform for the purpose of locating buried mines. The radar system is presently mounted on an 18-meter boom. We have successfully imaged a minefield located at the Nevada Test Site. The minefield consists of real and surrogate mines of various materials and sizes placed in natural vegetation. Some areas have been cleared for noncluttered studies. A technical description of the system will be presented, describing the wideband antennas, the video pulser, the receiver hardware, and the data acquisition system. The receiver and data acquisition hardware are off-the- shelf components. The data was processed using LLLNL-developed image reconstruction software, and has been registered against the ground truth data. Images showing clearly visible mines, surface reference markers, and ground clutter will be presented.

The Lincoln Laboratory ground-based rail SAR was used to collect UHF band data on buried and partially buried trihedral corner reflectors in Yuma soil. The frequency range was 0.25 to 1 GHz in discrete steps. Both HH and VV polarization data were collected in the vicinity of the pseudo-Brewster angle. The partially buried trihedrals revealed two principal components for the returned signals: (1) a surface reflected component, and (2) a ground penetrated component. A model is described for partially buried trihedrals that accounts for these two components and the model is used in estimating ground penetration parameters.

This paper describes site measurements and resulting images of buried objects made with the Earth Penetration Radar Imaging System (EPRIS) developed by Coleman Research Corporation (CRC). EPRIS makes use of frequency stepped radar technology and synthetic aperture imaging algorithms for nonintrusive characterization and imaging of buried objects, contamination, and geological or hydrological features. This paper is an extension or follow-up to CRC's EPRIS paper presented at last year's OE/AEROSPACE convention in Orlando, FL. It gives a brief description of the EPRIS system and contains the results from several DOE site surveys. These results include 2D and 3D images of buried test targets as well as images of actual buried waste and hydrological or geological features. The paper concludes with the recommendations or suggestions that should be followed up on future efforts.

This paper describes the significant results of shipboard and airborne studies of some oceanic processes by means of multispectral mm-wave technique. The remote sensing data and in- situ measurements are analyzed. The qualitative model for possibility of microwave diagnostics of the deep oceanic processes and underwater objects is discussed.

We demonstrated that radio imaging method (RIM) surface-to- surface, borehole-to-surface, and borehole-to-borehole sensing technologies at the Otay Mesa test site east of San Diego, CA could detect and delineate a horizontal 4 X 6-foot (cross- section) tunnel buried at a depth of approximately 45 feet. Utilizing monochromatic, continuous wave electromagnetic signals from a magnetic dipole source operating in the range between 22 kHz and 15 MHz, we confirmed the effectiveness of two general approaches: (1) mapping the electrical conductivity contrast between the country rock (sandstone) and the tunnel (i.e. the void and surrounding desiccation fractures) and (2) locating a cable (i.e. conductor) within and running the length of the tunnel from its induced, secondary radiation. Surface-to-surface RIM, utilizing a gradiometer receiver, mapped the 2D plan view location of the tunnel. Borehole-to-surface delineated both the depth and plan view location of the tunnel. Borehole-to-borehole RIM delineated the depth of the tunnel.

The United States Department of Energy is facing a large task in characterizing and remediating waste tanks and their contents. Because of the hazardous materials inside the waste tanks, all of the work must be done remotely. The purpose of this paper is to show how to reconstruct an enclosed environment from various scans of a Laser Range Finder. The reconstructed environment can then be used by a robot for path planning, and by an operator to monitor the progress of the waste remediation process. Environment reconstruction consists of two tasks: image processing and laser sculpting. The image processing task focuses first on reducing the quantity of low-confidence data and on smoothing random fluctuations in the data. Then the processed range data must be converted into an XYZ Cartesian coordinate space, a process for which we examined two methods. The first method is a geometrical transform of the LRF data. The second uses an artificial neural network to transform the data to XYZ coordinates. Once an XYZ data set is computed, laser sculpting can be performed. Laser sculpting employs a hierarchical tree structure formally called an octree. The octree structure allows efficient storage of volumetric data and the ability to fuse multiple data sets. Our research has allowed us to examine the difficulties of fusing multiple LRF scans into an octree and to develop algorithms for converting an octree structure into a representation of polygon surfaces.

Precise dual-band IR (DBIR) thermal imaging provides a useful diagnostic tool for wide-area detection of defects from corrosion damage in metal airframes, heat damage in composite structures and structural damage in concrete bridge decks. We use DBIR image ratios to enhance surface temperature contrast, remove surface emissivity noise and increase signal-to-clutter ratios. We clarify interpretation of hidden defect sites by distinguishing temperature differences at defect sites from emissivity differences at clutter sites. This reduces the probability of false calls associated with misinterpreted image data. For airframe inspections, we map flash-heated defects in metal structures. The surface temperature rise above ambient at corrosion-thinned sites correlates with the percentage of material loss from corrosion thinning. For flash-heated composite structures, we measure the temperature-time history which relates to the depth and extent of heat damage. In preparation for bridge deck inspections, we map the natural day and night temperature variations at known concrete slab delamination sites which heat and cool at different rates than their surroundings. The above- ambient daytime and below-ambient nighttime delamination site temperature differences correlate with the volume of replaced concrete at the delamination sites.

Radiography of large dense objects often require the use of highly penetrating radiation. For example, a couple of centimeters of steel attenuates 50 keV x-rays by a factor of approximately 10^-14 whereas this same amount of steel would attenuate a 500 keV photon beam by only a factor of about 0.25. However, this increase in penetrating power comes with a price. In the case of x-radiation there are two bills to pay: (1) For projection radiography, this increase in penetration directly causes a corresponding decrease in resolution. (2) This increase in penetration occurs in a region where the interaction of radiation and matter is changing from absorption to scattering. In the above example the fraction of scattering goes from about 0.1 at 50 keV to over 0.99 at 500 keV. These scattered photons can significantly degrade contrast. In order to overcome some of these difficulties, radiography using scattered photons has been studied by myself and numerous other authors. In all the above cases, calculation of the intensity of scattered radiation is of primary importance. In cases where scattering is probable, multiple scattering can also be probable. Calculations of multiple scattering are generally very difficult and usually require the use of extremely sophisticated Monte Carlo simulations. It is not unusual for these calculations to require several hours of CPU time on some of the worlds largest and fastest supercomputers. In this paper I will present an alternative approach. I will present an analytical solution to the equations of double scattering, and show how this solution can extended to the case of higher order scattering. Finally, I will give numerical examples of these solutions and compare them to solutions obtained by Monte Carlo simulations.

In this paper, radar cross section (RCS) models of buried dipoles, surface steel pipe, and buried steel pipes are dicussed. In all these models, the ground is assumed to be a uniform half space. The calculated results for the buried dipoles and the surface steel pipe compare favorably with those measured in the 1993 Yuma ground penetration radar (GPR) experiment. For the buried dipoles, a first-order RCS model is developed. In this model, a solution for an infinitely long conducting cylinder, together with a mirror image approximation (which accounts for the coupling between the dipole and the ground-air interface) is used to calculate the dipole RCS. This RCS model of the buried dipoles explains the observed loss of dipole RCS. For the surface steel pipe, a geometrical optics model, which includes the multipath interaction, is developed. This model explains the observed multipath gain/loss. For the buried steel pipes, a zero order physical optics model is developed. Also discussed is desert radar clutter statistics as a function of depression angle. Preliminary analysis, based on samples of Yuma desert suface profiles, indicates that simple rough-surface models cannot explain the observed average backscatter from desert clutter.

A subsurface-imaging synthetic-aperture radar (SISAR) has potential for application in areas as diverse as non- proliferation programs for nuclear weapons to environmental monitoring. However, subsurface imaging is complicated by propagation loss in the soil and surface-clutter response. Both the loss and surface-clutter response depend on the operating frequency. This paper examines several factors which provide a basis for determining optimum frequencies and frequency ranges which will allow synthetic-aperture imaging of buried targets. No distinction can be made between objects at different heights when viewed with a conventional imaging radar (which uses a 1D synthetic aperture), and the return from a buried object must compete with the return from the surface clutter. Thus, the signal-to-clutter ratio is an appropriate measure of performance for a SISAR. A parameter-based modeling approach is used to model the compelx dielectric constant of the soil from measured data obtained from the literature. Theoretical random-surface scattering models, based on statistical solutions to Maxwell's equations, are used to model the clutter. These models are combined to estimate the signal-to-clutter ratio for canonical targets buried in several soil configurations. Results indicate that the HF spectrum (3-30 MHz), although it could be used to detect certain targets under some conditions, has limited practical value for use with SISAR, while the upper VHF through UHF spectrum ($AP100 MHz - 1 GHz) shows the most promise for a general purpose SISAR system. Recommendations are included for additional research.

The adaptive matched filter was implemented as a spatial detector for amplitude-only or complex images, and applied to an image formed by standard narrowband means from a wide angle, wideband radar. Direct performance comparisons were made between different implementations and various matched and mismatched cases by using a novel approach to generate ROC curves parametrically. For perfectly matched cases, performance using imaged targets was found to be significantly lower than potential performance of artificial targets whose features differed from the background. Incremental gain due to whitening the background was also found to be small, indicating little background spatial correlation. It is conjectured that the relatively featureless behavior in both targets and background is due to the image formation process, since this technique averages together all wide angle, wideband information. For mismatched cases where the signature was unknown, the amplitude detector losses were approximately equal to whatever gain over noncoherent integration that matching provided. However, the complex detector was generally very sensitive to unknown information, especially phase, and produced much larger losses. Whitening under these mismatched conditions produced further losses. Detector choice thus depends primarily on how reproducible target signatures are, especially if phase is used, and the subsequent number of stored signatures necessary to account for various imaging aspect angles.

This paper presents an algorithm for image reconstruction of ground-penetrating synthetic aperture radar that can be implemented in real time. The algorithm permits underground focusing. The algorithm was successfully demonstrated at scale using a Ka-band radar in the laboratory that has 1 cm range resolution. The equipment utilized objects on the surface and at depths of 7.5 and 15 cm. With the imaging set for focus at the surface, the buried objects were not detected. The buried objects were detected and resolved to the theoretical limits with the focus appropriately set, with the surface object detected but blurred. Thus, the algorithm provides better detection and resolution of underground objects than algorithms sans underground focus, and also permits an estimate of the depth.

The ultraviolet and visible imaging and spectrographic imaging (UVISI) experiment consists of five spectrographic imagers and four imagers. These nine sensors provide spectrographic and imaging capabilities from approximately equals 110 nm to approximately equals 900 nm. The spectrographic imagers (SPIMs) share an off-axis parabolic design in which selectable slits (1.00 degree(s) X 0.10 degree(s) or 1.00 degree(s) X 0.05 degree(s)) provide spectral resolutions between approximately equals 0.5 nm and approximately equals 4.0 nm. SPIM image planes have programmable spectral dimensions with 68, 136, or 272 pixels and programmable spatial dimensions with 5, 10, 20, 40 pixels. A scan mirror sweeps the slit through a second spatial dimension and generates a spectrographic image once every 5, 10, or 20 seconds. The four imagers provide narrow-field and wide-field viewing. Each imager has a six-position filter wheel that selects various spectral regimes and neutral densities. Each of the nine sensors use intensified CCD detectors that have an intrascene dynamic range of approximately equals 10³ and an interscene dynamic range of approximately equals 10⁵; neutral density filters provide an additional dynamic range of approximately equals 10^2-3. An automatic gain control adjusts the intensifiers to scenes of varying intensity. UVISI also includes an image processing system that uses the raw data from any single imager to acquire and track targets of various sizes, shapes, and brightnesses. The image processor relays its results to a master tracking system that uses the UVISI data (as well as other data) to point the satellite in real time. UVISI will be launched on the MSX satellite in late 1994 and will investigate a multitude of celestial, atmospheric, and point sources during its planned five-year lifetime.

Sandia National Laboratories has developed a fieldable wide-angle detection system which utilizes wide dynamic range spectrometer and radiometer subsystems to generate simultaneous, independent measurements of incident optical radiation collected through a common aperture. The large dynamic ranges of the subsystems can create large amounts of continuous data which must be processed in real time to avoid saturating the system. Thus, the spectrometric and radiometric data are sent to a system processor subsystem which, due to the inherent sensitivity and timing differences between the two sensor subsystems, executes a complex data fusion algorithm in an effort to fully characterize the incident radiation. The raw subsystem data and the fused data are logged to a system disk and displayed on an operator display.

In this paper, we present an approach to improve weak signal detection in a non-Gaussian environment. This solution is developed under the assumption that the interference is described by a spherically invariant random process. As such, the weak signal detector reduces to a conventional correlator, modulated by a zero-memory nonlinearity prior to threshold processing. This receiver is designed for operation in those regions of the angle- Doppler space where target returns and interference are coincident, and not separable through conventional space-timing filtering.

This paper describes a Phillips Laboratory internal design for a high sensitivity, large field of view IR acquisition camera. Currently, the acquisition of a satellite with the 1.5 meter telescope of the Starfire Optical Range typically requires a sunlit target and dark sky. However, the level of thermal radiation from such a satellite is often sufficiently high in the long wavelength IR (LWIR) to permit detection with ground based telescopes irrespective of target illumination. The drawbacks of LWIR acquisition include the high levels of thermal radiation from both the telescope and the atmosphere which pose two constraints: (1), the 'background signal' usually exceeds the target signal and must be removed on time scales over which it is relatively constant, and (2), associated with the background signal is a noise level that dominates all system noise sources. The background signal level at the detector array for our application varies between 10¹⁵ to 10¹⁶ photons sec^-1 cm^-2, depending on the IR bandpass used. Our optical design for the LWIR acquisition camera maps a 128x128 pixel detector array onto a two milliradian (mrad) scene. The optical design uses two aspheric lenses, one to re-image the field onto a cold field stop, and the telescope pupil onto a cryogenic chopping mirror and collocated radiation stop. The second lens re-images the field stop onto the detector array. Aberrations are designed to be better than diffraction limited over the entire two mrad field of view. The end product of the acquisition system is a video display of the IR scene, with the background signal removed. A user then positions mouse-driven cross hairs over a target in the scene. The resulting position and time update is used to revise the target ephemeris, and to provide pointing information for target acquisition by other SOR tracking platforms.

An integrated optics, controls, and structures modeling tool has been developed to analyze the performance of complex electro- optical (EO) sensing systems. Hosted within an object-oriented graphical environment (Khoros) developed by the University of New Mexico, complex systems such as active ground-based telescopes, airborne spectrometers, and space-based sparse array telescopes can be simulated and rapidly evaluated. The TAOS model integrates data products from existing codes such as MATLAB, CODE 5, NASTRAN, and others to allow multi-disiplinary parametric analysis of system performance. Because the model includes accurate physical optics and radiometric representations, almost any function of an optics system can be quickly generated and studied. In addition, degrading effects of dynamic structures, use of compensating control systems, and effects of the observing environment (wind load, boundary layer, and seeing) can also be included. Use of this simulation tool on NASA programs such as the Space Telescope Imaging Spectrometer has reduced design schedules by factors of three. Other typical analysis applications include the study of atmospheric compensated imaging systems using combined adaptive optics/post-processing techniques, simulation of hyper-spectral imagers, and methods for achieving coherent phasing of telescope arrays. This paper also provides a progress report on TAOS modeling of the European Southern Observatory (ESO) Very Large Telescope (VLT).

`The demand for high detectivity LWIR IR focal plane arrays that operate at low backgrounds is shown to drive the HgCdTe technology toward increased detector performance. Reduced operating temperature together with advanced material technology and detector design are presented as solutions. High performance MWIR, MLWIR and LWIR HgCdTe detector test arrays and variable area test structures were recently demonstrated through the joint collaboration of Aerojet Electronic Systems Division and Rockwell International. These devices are based on the innovative buried planar heterostructure (BPH) detector architecture grown by liquid phase epitaxy of HgCdTe on II-VI substrates. The major features of the BPH design include planar geometry, heterostructure wide gap p-type on narrow gap n-type HgCdTe and a buried LWIR electrical junction. Excellent 78K median R_(omicron )A performance across the IR spectrum from 5.2 micrometers to 12 micrometers is reported and shown to follow the diffusion trend line. Excellent 40K median R_(omicron )A performance for devices with cutoffs ranging from 9 micrometers to 19 micrometers are also presented. LWIR R_(omicron )A statistical performance data at both 78K and 40K from fanout test arrays are presented with median R_(omicron )A values of 100 ohm-cm² at 78K and > 10⁶ ohm-cm² at 40K for cutoffs of 10.4 micrometers and 11.4 micrometers respectively. The 90% test array operability was found to exceed 5 x 10⁵ ohm-cm² at 40K. Devices with median R_(omicron )As of 20 ohm-cm² at 78K and 7 x 10⁵ ohm-cm² at 40K were measured for cutoffs of 12 micrometers and 13 micrometers respectively. Uniform and high quantum efficiencies were measured at 40K with a median of approximately equals 70%.

This paper describes the implementation of a modular, decentralized surveillance system which incorporates a range of sensors including TV cameras, ultra-sonic and IR devices, and optical barriers. The key features of the approach are fault tolerance, modularity, and scalability, which are achieved through the use of a Decentralized Kalman Filter (DKF) as the main data association and tracking technique, and Dempster- Schafer evidential reasoning as the basis for combining estimates of target identity from the various sensors. The surveillance system is able to track multiple objects from multiple sensors, and can provide estimates of target identity fused over time. Results are communicated to the user through a graphical interface implemented under X Windows, which supports the designation of 'exclusion zones' where the user can specify conditions for the triggering of an alarm.

1.1 Prior art In the past , multispectralimaging instruments were generally custom designed to suite a particular requirement or need. This meant that the imagers were either of simplistic single function or they were complex, expensive, and customized. In the Eighties ,withthe development of CCD technology ,manyof the existing film based systems were transitioning to electro-optical systems.One driving reason for the interest in electrooptical systems was the near real-time acquisition. A second key driver was the lower material and logistics costs. 1.2 New technology Now ,theadvent of High Definition television in the United States requiring high resolution and color accurate imaging and display devices ,hasprompted new technological developments in CCD imagers1'2,high data rate digital recording3' and display devices capable of displaying 2 million pixels with 24 bit color.High Definition (HD)has pushed the technological envelope enabling high resolution imaging technology to enter the domain of the multispectral reconnaissance community. 1.3 Application to reconnaissance Until recently most of the reconnaissance cameras had to be custom developed due to the lack of existing technology to meet the requirements of the application. Typically the cost of focal plane development was prohibitively expensive, costing 2-15 million dollars for simple linear arrays; therefore, only few varieties were developed. High definition technology offers to reconnaissance camera designers visible focal planes 1920 x 1036 pixels with frame rates of 30 frames/sec ,small 3 color prism /CCD optical blocks for multispectral capability, dynamic range of 10 f/stops or 72 db, and a sensitivity of f/8 at 2000 lux. On the recording side, High Definition technology offers 1.2 GBit/sec digital recording devices with a 63 minute capacity or 5400 frame write-once laser disc recorders. HD offers two unique capabilities to reconnaissance namely : (1) Color (multispectral) and (2) Real-time ( adding temporal to spatial information). HD also provides a family of compatible imaging, recording and display devices that are cost effective.

Delta-doped CCDs have achieved stable quantum efficiency, at the theoretical limit imposed by reflection from the Si surface in the near UV and visible. In this approach, an epitaxial silicon layer is grown on a fully-processed commercial CCD using molecular beam epitaxy. During the silicon growth on the CCD, 30% of a monolayer of boron atoms are deposited nominally within a single atomic layer, resulting in the effective elimination of the backside potential well. These devices are highly uniform and have exhibited long-term stability. To achieve significantly higher total quantum efficiency, antireflection layers can be directly deposited on the device. This was demonstrated in the 250-400 nm region.

Many radar systems need to be able to accurately determine a target's height above terrain. In airborne early warning (AEW) systems, the radar antenna is limited in its vertical aperture, thus producing a broad beamwidth in elevation. This reduces its curacy for height fmding. An alternate method of height fmding is to measure the delay of a ground-bounce (multipath) signal from the target, referenced to the direct line of sight path. This has been demonstrated successfully with AEW radars which operate over water in certain situations, but has had limited success over land. The problem has been the lack of an accurate, robust signal processing algorithm for determining the time delay between closely spaced direct and ground bounce returns. Our basic objective was to make credible the premise that an airborne AEW radar can accurately determine height of targets by processing the delayed echo due to the multipath ground bounce. Current AEW systems use this technique, but in a limited way -usually only over water, where the surface reflection is strong and predictable and when it is well separated from the direct reflection. It has been recognized for some time that land also can cause multipath reflections, but due to its irregular nature, this technique has not been exploited thoroughly. Therefore, our objectives were to show height finding can be done accurately when the direct pulse overlaps the specular return (over water or land). The signal processing problem is essentially one of performing time-of-arrival estimation of two or more pulse returns; the direct plus one or more ground bounce echoes. For typical AEW scenarios, the echoes may overlap the direct return and are usually of lower amplitude. Therefore, the algorithm must make use of the maximum information content of the signal and should have as low a threshold signal to noise ratio as possible in order to apply in the greatest number of conditions. This problem will also occur in laser radar systems, and has an exact analog for the phased-array direcfion-of-arrival estimation. The signal processing results of this paper can be applied to pulsed or frequency modulated continuous wave radar/ladar systems. We assume that the target has been detected and that it is of interest to estimate the target's height above terrain. This processing would occur at baseband using a complex demodulated channel. In general, some form of averaging is often used to enhance the SNR of small signals, such as Doppler processing (the technique is described later in this paper) and the algorithms are shown to be compatible with these operations. The algorithm could be used in some situations for enhanced detection as well. Using knowledge of the terrain, the surveillance aircraft altitude and the time delay estimates of the echoes, we can infer target height. Concurrent with the basic objective, we gathered an extensive, fairly high-resolution data set of the surface reflection of various terrain types at two radar hand frequencies: 430 MHz (UHF) and 1255 MHz (L-band). Data were to be collected for each polarization: horizonial, vertical, and cross-polarization. The main terrain of interest was rugged terrain; the predominant view being that the echo data taken in very rugged terrain would be the most difficult to extract. Calibration data were collected over water, and much data of fairly flat, predictable terrain were also taken.

Lincoln Laboratory, Massachusetts Institute of Technology has built and tested the space-based visible (SBV) sensor to be flown on the Ballistic Missile Defense Office's Midcourse Space Experiment spacecraft. SBV, one of a group of sensors on the spacecraft, is designed to perform above-the-horizon surveillance experiments and acquire visible/VNIR band data (450 to 950 nm) on targets and backgrounds. This paper describes the flight configuration of SBV and some calibration results.

Characterization of an acousto-optic tunable filter (AOTF) is performed by measuring the filter's laser line response, tuning relationship, and diffraction efficiency. An imaging spectrometer that utilizes the filter is described. The system is comprised of an optical system, AOTF filer, dual focal plane CCD camera, and a control computer. Data from the system is presented.

Each device ror radiation registration in radio range containes an antenna. Mainly it is the antenna dimention the sensitivity o such a device belnp determined by. Can the antenna ror registration or' more short wave radiation be constructed? The main reature o antenna action is tile conversion o the insident radiation mode into the mode passing through antennaAt this moment the radiation brightness (which is equivalent to a number or photons per mode ) can increase . In accordance WI th the geometry optics (Shtraubel theorem) the lenth and mirror systems cannot raise the radiation brightness in principle and cannot be treated an antennas.

The development of surveillance technologies based on remote detection of anomalies of gaseous (atomic) composition of media near industrial objects, underground storage of oil and gas mains, as well as along trajectories of space objects is reported. Remote correlation spectroscopy of gas plumes and development of surveillance technologies are discussed.

Skipper is the third space experiment in the Bow Shock series to obtain aerothermochemistry and emission data from shock-heated layers. Onboard instrumentation will include two scanning spectrometers and 20 photometers. The spectrometers will scan over the range of 0.2 to 0.4 micrometers . The photometers will be designed to view the VUV and UV wavelengths with emphasis on atomic oxygen, Lyman-alpha, NO, OH, and N₂+ wavelengths. The mission starts with launch into a 822 km circular orbit at 97 degree(s) inclination. Utah Sate University designed Skipper with their instrumentation module integrated on top of the Russian spacecraft bus. After spacecraft checkout in the 822 km orbit, the satellite uses hydrazine engines to change to an elliptical orbit with a perigee of about 180 km and begins the scientific measurements. The experimenters will then lower the perigee farther (in approximately 10 km steps) to increase the signal to noise ratios, as drag and thermal limits permit. These experiments will be completed in a two week period, followed by positioning the satellite for reentry over a Pacific test range. Additional data will be collected during the reentry (until the satellite burns up) using both onboard instrumentation and ground observation systems. Thermal modeling predicts that data can be collected down to about 80 km (at a speed of 7 km/sec).

In the past government and private industry have produced hazardous waste in ever increasing quantities. These untold millions of tons of environmentally dangerous wastes have been disposed of by undocumented burial, simple carelessness, and purposeful abandonment. Society has recently dictated that before new construction may be initiated, these wastes must be found and cleaned up. The first step is to locate these undocumented waste depositories. The noncontact, nondestructive, remote sensing techniques of computer enhanced IR thermography and ground penetrating radar, may be used to detect buried waste sites, buried tanks/pits, and tank/pit leak plumes. These technologies may be used from mobile vehicles, helicopters, or man-portable systems and are able to cover tens of acres per day depending upon the system fusion method used. This relatively new combination of technologies will be described in theory by procedure and the use of case studies based upon successful projects.

The use of scattered radiation for radiography has many potential advantages over conventional projection techniques: for high energy photons the scattering process strongly dominates all other processes. The intensity of scattered radiation is due directly to the electron density and highly insensitive to chemical composition. Finally, the use of scattered radiation allows the investigator to position the radiation source on the same side of the object as the detector. In this paper I will present some recent results of a set of measurements made with our uncollimated Compton backscattering tomography apparatus. This technique uses the Compton energy shift of scattered gamma rays to determine the scattering site. By measuring the spectrum of these scattered gamma rays it is then possible to determine the electron density of the object being investigated. I will give a brief description of the apparatus and present the results of numerous measurements made on a brass phantom with voids placed at various depths. These results imply that for this crude apparatus occlusions as small as one cubic millimeter may be located to an accuracy of about one millimeter at depths of about 15 millimeters in solid brass.

In the last 10 years passive IR based (8 to 12 microns) motion sensing has matured to become the dominant method of volumetric space protection and surveillance. These systems currently cost less than $25 to produce and yet use traditionally expensive IR optics, filters, sensors, and electronic circuitry. This IR application is quite interesting in that the volumes of systems produced and the costs and performance level required prove that this is potential for large scale commercial applications of IR technology. This paper will develop the basis and principles of operation of a staring motion sensor system using a technical approach. A model for the motion of the target is developed and compared to the background. The IR power difference between the target and the background as well as the optical requirements are determined from basic principles and used to determine the performance of the system. Low cost reflective and refractive IR optics and bandpass IR filters are discussed. The pyroelectric IR detector commonly used is fully discussed and characterized. Various schemes for `false alarms' have been developed and are also explained. This technology is also used in passive IR based motion sensors for other applications such as lighting control. These applications are also discussed. In addition the paper will discuss new developments in IR surveillance technology such as the use of linear motion sensing arrays. This presentation can be considered a `primer' on the art of passive IR motion sensing as applied to surveillance technology.

The past decade has seen extensive development of strategic IR focal plane arrays, with the result that surveillance, tracking, and interceptor sensors are a much more credible force for national and theater defense. Investment in IR detector materials, especially HgCdTe, has resulted in breakthrough improvements in array sensitivity, uniformity, and size, making these materials viable for the vital strategic defense systems currently envisioned for deployment. Development of silicon impurity band conductor detector arrays has resulted in arrays for the very long-wave IR that approach theoretical limits for performance in the surveillance applications of tomorrow. Programs for the development of readout circuitry have allowed array sizes to increase dramatically, while permitting longer operational lifetimes in space radiation environments with reduced electronics noise. Efforts under these development programs to cut array costs, while improving yield and performance, are preparing us for programs to manufacture the number required at a cost that will allow the surveillance system to be affordable. This paper presents an overview of space sensor missions, technical progress from recently completed programs, status of ongoing efforts, and speculation about development needs and directions for the future.