High technology is shrinking the sky, ground, and sea. With advanced electro-optic, infrared, and millimeter wave systems, objects in the sky or on the ground and sea can be detected, recognized, identified, and eliminated, if that is the goal, all before these objects can be seen with the naked eye. The advent of modern systems, however, has also resulted in sensitivities to environmental factors above and beyond those commonly associated with the weather. At issue then is whether the system will function as it was designed to function when one needs it. That means designing equipment to function under adverse environmental conditions when practical. If this is not practical, then the system's deficiencies and the environmental conditions that cause them must be understood so that systems are not depended upon to function when the design criteria are exceeded. This would allow for optimum system utilization and proper system selection for the application to environmental conditions of interest. It would also allow for effective countermeasures or supply opportunities to take advantage of systems used against you. Hence, if it is not practical to design around environmental effects, then methods and environmental sensors must be developed to mitigate those adverse effects. New operational environmental support requirements must be identified at an early stage so that the operational capability for that support will be available when the material enters the inventory. This will optimize system utilization in an adverse environment.

Fifteen electro-optical obscuration models in use within the Army are examined in terms of input and output requirements, and 18 data bases from major Army obscuration effectiveness tests are examined and summarized. Tables showing side-by-side model data requirements and test measurements on hand are presented along with short descriptions of each model and test. The results are discussed in relation to strengths and deficiencies in current modeling and testing capabilities.

As the field of optical engineering grows, Optical Engineering is growing with it. The next step in that growth has been approved by the SPIE Board of Governors. I n this editorial, I want to suggest some of the effects we can expect from that decision and why that decision was a difficult one to make.

A brief description of each of the eighteen modules contained in the 1982 version of the Electro-Optical Systems Atmospheric Effects Library (EOSAEL 82) is given together with the purpose of the module. References are included to direct the reader to detailed technical material on the models. The spectral range of application of the models is given in tabular form. A brief description of the EOSAEL computer code is included.

Measurements have been made with radars from 35 to 217 GHz of near-earth propagation through both natural and cultural obscurants. Results of measurements made in rain, fog, snow, high humidity, dust, and some smokes are presented for the major millimeter wave windows. Some modeling performed by other agencies is presented for comparison.

Increasing emphasis is being placed on the study of the effects of atmospheric turbulence on the propagation of millimeter and submillimeter waves because of the potential usefulness of these frequency bands in both military and civilian applications. The characterization of millimeter wave turbulence effects is more complicated than that of the optical propagation case because of a strong dependence on the humidity structure parameter CO2, as well as on the temperature structure parameter Gr2. In addition, there is a dependence on the cross-correlation of these two parameters, denoted by CI-0. Measured results on the effects of atmospheric turbulence on millimeter wave propagation, which include both amplitude and phase fluctuations, are very limited and have generally been obtained incidental to other propagation measurements. However, comparison of these limited experimental results with theory has shown good agreement. This paper compares scattered results measured at 35, 94,140, and 220 GHz to theory, and shows that agreement in most cases is plausible. A future experiment specifically designed to characterize millimeter wave turbulence, with special emphasis on measurement of the pertinent atmospheric parameters, is also described.

The phase function of smoke produced by dropping premier grade diesel fuel on a hot soldering iron was measured using a polar nephelometer. Measurements of the polarized and depolarized components were made at 0.6328 micrometers. The polarized components of the phase function exhibit a strong forward scattering peak, a shoulder extending to approximately 60°, a region of very weak scattering between 60° and 115°, and a backscattering region. The depolarized components are quite weak, within the range of experimental error, leading to the conclusion that smoke particles are spherical.

Wind speed and relative humidity have been the physical variables used in empirical expressions for equilibrium marine aerosol distributions. Recent formulations, which include the role of hydrostatic stability because it influences turbulent transport and entrainment of clear air from aloft, are examined on the basis of 1 um radius aerosol number density values. The aerosol data were collected along with a quite complete meteorological data set in the Northeast Atlantic during the international Joint Air Sea Interaction Experiment (JASIN-78). The 1 um number density values are normalized for generation and relative humidity influences, and analyses are performed to gain reasonable assurance that the aerosol were of sea salt origin. A stability influence was observed in the normalized number density results, but it was less than that predicted by a flux-profile relationship in which the only removal velocity was the gravitational fallout rate. Better agreement occurs when the entrainment rate of overlying air into the boundary layer is added as a removal velocity. This indicates that entrainment of clear air from aloft dilutes the near surface marine aerosol number densities a measurable amount.

The total aerosol optical depth p is the sum of three components: the stratospheric, us; the upper tropospheric um and the marine boundary layer, um. The extinction coefficient at the sea surface ao can be calculated from ao = f(u-us-um)/h, where h is the height of the boundary layer and f is a factor that accounts for the height dependence of aerosol extinction in the boundary layer. A boundary layer aerosol model is presented that explains the height dependence of a. Both f and h depend on the general synoptic weather pattern. This is demonstrated using a set of aircraft aerosol profiles measured over the Pacific Ocean in the vicinity of Monterey, California.

A model is presented which predicts optical and infrared extinction and absorption from marine aerosol for wavelengths of 0.2 to 40 micrometers. The model utilizes standard meteorological measurements as inputs but has default values built into it so that input values are not absolutely necessary, but when they are available they will increase the accuracy of the predictions. The model is based on aerosol size distribution measurement data taken by several investigators from platforms close to the sea surface. The optical predictions of the model are derived from precalculated terms stored in the program which were originally obtained from lengthy Mie calculations on special aerosol size distributions.

The propagation of radiation through a cloud depends on the concentration and size distribution of drops. A series of aerosol measurements in various types of fogs and hazes shows a direct relationship between a subset of the dry aerosol and fog drops. These measurements allow identification of the specific aerosol component (fog condensation nuclei, FCN) upon which fog droplets condense. The extensive variability of these particle concentrations can be seen in the preliminary FCN climatology which is presented. It is shown that the variability in fog drop concentration is largely due to differences in FCN concentrations which are characteristic of various air masses.

The wavelength location of extinction spectra peaks for individual particles depends on their size, shape, and orientation. An aerosol cloud consists of many particles with a collection of sizes, shapes, and orientations. When electromagnetic radiation passes through a cloud, the individual particle extinction spectra add together, and the resulting extinction spectra for the particle ensemble become essentially flat. This occurs for particle sizes approximately on the order of and larger than the wavelength measured inside the particle. The flat spectra depend only upon particle size and shape distribution and are independent of complex refractive index. At particle sizes smaller than this, Rayleigh scattering and absorption takes place, and extinction spectral peaks will be observed for the particle ensemble in regions of anomalous dispersion. In the Rayleigh region extinction, when dominated by absorption, will depend upon particle shape distribution and complex refractive index but will be independent of size distribution. Metal particles have a complex refractive index that is strongly dependent on wavelength; however, for most other particles with weaker refractive index dependence on wavelength, there will be an inverse wavelength dependence in the Rayleigh absorption spectra and an inverse fourth power wavelength dependence in the Rayleigh scatter spectra.

The optical properties of falling snow depend on physical characteristics such as snowflake size, density, and concentration. A semiempirical model is being developed to determine falling snow characteristics from micrometeorological conditions. The model is validated by comparing results to data taken during the U.S. Army SNOW ONE-A tests. Several of the inputs to the model are treated parametrically to provide a preliminary look at the sensitivity of optical properties to changes in meteorological variables.

A method is presented for extracting extinction coefficients from transmittance measurements in a scattering atmosphere. Computation of unscattered, first-order scattered, and second-order scattered contributions to received power are calculated by using the phase function of the scattering particles and the optical characteristics of the measuring system. The method has been applied to measurements at 0.6328 and 8 to 12 micrometers made in a falling snow consisting mainly of needle-type crystals 1.5 mm in length and 100 micrometers radius. The resulting extinction coefficients at the two wave-lengths were found to be equal.

Visible and infrared extinction in falling snow is a function of snow particle concentration and snow crystal size and shape. Relationships between existing meteorological conditions and these characteristics have been investigated using measurements made during the SNOW-ONE (Scenario Normalization for Operation in Winter-Obscuration and the Natural Environment) Field Experiment. Effects of meteorological conditions upon extinction are discussed, and empirical models are suggested. Causes of the variation of extinction with wavelength in the visible and infrared are identified, and the magnitudes of some of the possible effects are estimated.

Measurement data from a helicopter snow obscuration field test conducted at the SNOW ONE-A test at Camp Ethan Allen, Vermont, are discussed relative to temporal and spatial effects of helicopter-downwash-produced snow clouds on visible and infrared transmission. Two tests were conducted-one on December 15, 1981 and one on December 17, 1981. Intervening between these two dates was a snowstorm which left approximately 20 cm of new snow on the ground. During each test a helicopter performed several different flight patterns including hovering at fixed altitude, landing, rapid and slow descent, and forward motion flights, both perpendicular and parallel to the transmissometer line of sight. Application of the multispectral and temporal data for understanding transmission through helicopter-produced snow clouds is discussed. Also reported on briefly in this paper is the phenomenon of helicopter contrast enhancement resulting from obscuration of the (dark) background by the blowing snow cloud.

A mobile optical laboratory has been developed for the study of atmospheric electro-optical phenomena. This system offers significant advantages over previously fielded measurement hardware. The system incorporates 0.9 meter collecting optics; precision, motor-driven, optical support structures; secondary standard, broadband IR sources; visible and IR laser sources; a full duplex FM microwave data link; four transmissometer channels; four radiometer channels; and a high-resolution thermal imager. A modular system design combined with extraordinary mobility make this system a versatile research tool capable of addressing many diverse atmospheric electro-optical problems. A detailed description of the system is presented. The application of the system to the study of battlefield obscurant effects on electro-optical systems is demonstrated with specific examples.

The secondary mirror of an infrared telescope is attached to a unit which causes the mirror to oscillate, thus modulating the infrared signal. Since the plane of oscillation of the modulating unit is fixed, the change in direction of modulation necessary during observations must be obtained by releasing the unit from the supporting shaft, rotating it to the required angle, and then returning it to its seating with high precision. This series of operations is made possible in the device described here by the activation of an electromagnet, the field of which frees from its seating the shaft which carries the unit. After rotation, the shaft is recalled to its seating by two disk springs. Constructional details are given of the whole support system which includes the electro-magnetic device, supporting shaft, focusing system, and spider attachment to the upper ring of the telescope. The completed structure has been tested and mounted on the Italian National Infrared Telescope at the Gornergrat.

A new approach to blood vessel boundary estimation is presented in this paper. By appropriately modeling the blood vessel as a dynamically evolving state vector, and by taking into account the Poisson statistics of the x-ray imaging noise, we arrive at a state-space system with a nonlinear measurement equation which includes non-Gaussian, nonadditive noise. Maximum a posteriori (MAP) smoothing equations are derived for the state vector describing the vessel, and the optimally smoothed state vector is found by a dynamic programming search. This method performs especially well in images with low signal-to-noise ratio and low sampling rate. The performance of the proposed method is demonstrated by the boundary estimates obtained by applying the algorithm to a simulated vessel and measurement data as well as to real vessel phantom measurement data at various SNRs.

We report considerable success in using the technique of laser annealing to reduce scattering in a variety of thin-film optical waveguides deposited onto thermally oxidized silicon substrates. For the materials Si3N4, Nb2O5, and Ta205, values of waveguide loss less than 1 dB/cm were achieved. Values of waveguide loss as low as 0.01 dB/cm have been measured for laser-annealed ZnO waveguides and for Corning 7059 glass waveguides which have been both laser annealed and had surface coatings applied.

The design of an optical probe/camera objective having good image quality over an extended focusing range is described. Bearing some resemblance to a periscope, it simultaneously provides an image to both vidicon tube and photographic film. The entire system is used in the production of television commercials where a certain type of special effects may be required.

The operation of an optical observatory with commands and instructions passed from the laboratory computer to the observatory computer via telecommunications has enabled us to routinely operate unattended at a remote site three sophisticated optical instruments. We report on the scientific and instrumental considerations, software development, and hardware decisions that made this achievement possible.

A Wolter Type I x-ray telescope, intended both for astronomical observations and to serve as a prototype module for the large area modular array of reflectors (LAMAR) mission, is now in definition study under NASA's Spacelab program. The five mirror telescope presently being designed is to have a blur circle radius of 20 arc sec and an effective area of about 400 cm2 at 1/4 keV, 200 cm2 in the 0.5 to 2 keV range, and 50 cm2 between 2 and 5 keV. Future expansion to a full ten mirror telescope will approximately double these effective areas. A rotary interchange mechanism will allow either of two imaging proportional counters (IPCs) to be placed at the telescope focus; one operating between 0.15 and 2 keV and the other optimized for the 0.6 to 6 keV energy range. During flight, the telescope will utilize an instrument pointing system for a series of observations lasting from six minutes to several hours. This investigation has dual objectives: The primary objective is scientific and involves observational study of galactic and extragalactic x-ray sources, extending the work of the Einstein Observatory to much fainter sources and to higher energies. The second objective is to provide an assessment of the cost and improved performance of utilizing Wolter Type l x-ray optics for the LAMAR mission and to extend the technology for producing these optics to still higher angular resolution and toward lower cost.

Deposition of multilayered diffraction coatings on the reflecting surfaces of a Wolter Type I x-ray telescope offers the potential of using Bragg reflection to achieve enhanced effective area in selected high energy bandpasses. The structure of a gold-carbon multilayer has been optimized for study of 1.8 A iron-line emission with an x-ray telescope designed for observations from Spacelab. The response of this mirror assembly has been calculated as a function of x-ray energy, and the resulting effective area is enhanced by a factor of ten and peaks at 160 cm2 with a bandpass of 0.4 keV FWHM. This enhanced response is sufficient to allow study of the angular distribution of iron-line emission from the 20 brightest cluster x-ray sources during a seven day Spacelab mission. The possibility of achieving x-ray imaging in narrow bandpasses at even higher energies has been investigated. We conclude that it should be possible to achieve effective areas of approximately 5 cm2 in bandpasses -1 keV wide for energies in the 15 to 25 keV range, a spectral region of much importance during the impulsive phase of solar flares.

The possibility of considerably increasing the resolution of an extended image taken through a turbulent atmosphere by selecting random "lucky" diffraction limited exposures out of many normal-turbulence degraded-short exposures is experimentally explored. For an imaging aperture D, larger than the atmospheric spatial coherence length ro, the probability P of getting a diffraction limited short exposure image of a point source is found to be exp[-0.6(D/r0)2 ]. This result is in agreement with Fried's prediction. The angular isoplanatism is measured to be -X/ro. However, observed random wavefront tilts scramble the diffraction limited picture elements in an isoplanatic patch, thus complicating the probabilistic imaging method.

The present paper describes the basic principles and the geometries of certain simple catadioptric magnifiers that have been designed and fabricated. These magnifiers are made of moderately curved spherical surfaces and are capable of producing high visual magnifications with large eye-relief. Such magnifiers are found to be useful for reading microfiche having nominal frame sizes of 16mm X 12mm and 12mm X 9mm.

By illuminating a ground glass with a laser beam, a spatial field of speckles is created. These speckles are used as displacement gauging ele-ments of curved 3-D objects whose surfaces are coated with photosensitive material. Equations are derived to show that all three components of the surface displacement can be obtained from two specklegrams.

A technique of white-light color encoding of misfocused speckle interferometric fringe patterns is presented. The encoding is performed in the spatial frequency plane with color filters. This technique allows the viewing of a multiset of encoded speckle interferograms simultaneously. Thus, it may provide new informational interferometric aspects of the object under stress or vibration. The effect on the speckle fringe pattern due to the spatial filtering is briefly discussed, and experimental demonstrations of color encoded fringe patterns are presented. Due to the simplicity and versatility of the processing technique, we feel that the technique may develop into a practical tool for strain, stress, and vibrational measurement.

In this paper we report the observation of periodic oscillations and chaos in a hybrid optical bistable system with an optical delay and examine some of the practical aspects of these phenomena. A simple explanation of the square-wave output from such instabilities is given, along with a suggestion for possible all-optical square-wave generators.

The function of the cryogenic limb-scanning interferometer/radiometer (CLIR) is to observe infrared emissions of the earth's upper atmosphere from space. The earth's surface is an extended source of intense background radiation with a small angular separation from the desired scene. The CLIR employs an off-axis Gregorian telescope whose primary mirror and baffles are cooled by an open-cycle cryogenic system. A system of specular annular baffles has been designed to minimize both stray light problems and cryogen consumption by retromapping the aperture into itself. Off-axis rays which enter the aperture and strike the baffles are reflected so that they pass out of the aperture again and are not absorbed on cryogenic surfaces. The edge ray principle is used to configure the specular baffle surfaces. The baffle which lies closest to the aperture is an ellipsoid whose foci trace out the circular aperture on revolution about the axis. Its theoretical "ray trace" efficiency is 100 percent. A subsequent baffle has an elliptical cross section whose near focus traces out the central hole in the ellipsoidal baffle and whose far focus traces out the aperture. Its theoretical efficiency is about 90 percent. These baffles reduce the earth radiation heat load on the cryogenic cooler by an order of magnitude, changing it from the dominant cause of cryogen consumption to a relatively small effect. An aperture shield is also desirable to reduce cryogen consumption, stray light, and contamination.

A simple technique of producing two-dimensional hologram images with a slide projector is presented. The technique offers considerable flexibility, adaptability, and less stringent requirements for hologram construction as compared with the conventional two-dimensional laser holography. With this technique it may be possible to record three-dimensional objects of limited depth. Simple experimental demonstrations are given. We note that color hologram images can also be produced by this technique. By proper design, high quality hologram images may be obtained by this technique.