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In this article principles of operation of a coherent optical image correlator based on a well know optical joint transform correlator are examined. Theoretical predictions and experimental data for of the optical image correlator with a holographic filter recorded on a thin holographic photographic plates PFG - 01 are analyzed. Results of the operation of the dynamic joint transform correlator on the basis of cadmium fluoride crystal, CdF2, with bistable impurity centers are demonstrated. Calculated and experimental correlation peak intensity dependencies with the scale and angular mismatch between an observed and reference objects for static and dynamic joint transform correlators are compared. Tangram figures were used as a test images. In the paper all computations were performed by use of MATLAB 7.0.1 mathematical program.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The development of the wave nature of light, over the last 430 years, resulted in the off-axis or Leith hologram. Earlier contributions were expressions for the resolution of microscopes and telescopes and the first color photographs. X-ray diffraction by crystals and recorded photographically (actually "holograms" recorded without a reference beam) eventually produced images of atoms in crystals. D. Gabor was the first to add an in line reference beam to a diffraction pattern by passing a coherent beam through a tenuous scene. Interference between the light scattered by the scene and the unperturbed beam was recorded (as in crystallography by a photographic plate, the hologram). The message was reconstructed when the plate was re illuminated with colored light. It is believed that the off axis reference beam was discovered during the classified development of side looking radars. The invention of the visible helium neon laser clarified the importance of the off axis hologram which produces 3D imagery with continuous parallax (miracle #1) of the recorded scene. It was found that the off axis hologram reconstructed the amplitude and phase of the original wavefront, making possible interferometric comparisons (miracle #2). Reconstruction of the conjugate wavefront was achieved by reversing the direction of the reconstructing beam (miracle #3). Phase conjugated holograms makes possible 3D microscopes and can be used to correct different optical systems. In hind sight, it could be said that the off axis or Leith hologram was too obvious, as are all other great discoveries.

We achieved the motion pictures of the ultrashort laser pulses propagating in air and some optical devices using the light-in-flight recording by holography. The pictures are recorded with a ~ 10-ps and a 130-fs pulsed laser, and a photographic plate. To reconstruct the motion pictures, the hologram is illuminated with a continuous wave (cw) laser, and the hologram is moved in parallel to the plane on which the recording material was set. The motion pictures can be also seen in the following two other cases. (1) We move in parallel to the hologram while the hologram is illuminated with a cw laser. (2) We stop to see the hologram scanning the hologram with the cw laser beam. The motion pictures are continuous in terms of both time and space. The reconstruction speed of the motion pictures is determined by the speed of the moving or the scanning. We demonstrate motion pictures of the ultrashort laser pulses going through several optical elements. Fundamental optical phenomena such as reflection, refraction, and diffraction are occurring are observed for the ultrashort laser pulse. We discuss the resolution of the motion pictures.

the photographic plate fixed to one point of the object under study and plane illumination normal to and through the plate,some interesting advantages can be obtained. The stability requirements are drastically reduced (a general translation anda rotation around an axis parallel to the illumination direction can be allowed); the optical set-up is very simple; white-lightreconstruction can be used.

The portable holographic camera for manufacturing high- quality volume reflection holograms reconstructed optically by white light has been designed. The holographic setup comprises a low-power He-Ne laser. The design of the holographic camera is the development of the holographic sandbox technique. High-silica sand is used for mechanical and temperature stabilization. A rigid mounting of an object and photographic plate is not provided for the construction of the holographic camera. This makes possible the high rate of photographic plates changing. The processing arrangement is designed for manufacturing several tens of high-quality reflection holograms in one operating cycle. The portable holographic camera has been used very successfully for making holograms of museum objects.

The PtSi IR CSD was evaluated for astronomical purposes. The device has enough potential to apply for the astronomical uses. Several collaborations are being promoted with the camera. The infrared cameras are reopening infrared windows to the universe since they realize very efficient observations. The appearance of the infrared camera is one of the biggest breakthroughs in the astronomical instrument like that of the photographic plate. The collaboration of the infrared camera is very important both in science and scientific activity of the countries where the camera is not available because of less efficiency of the conventional infrared instrument. The PtSi camera projects under collaboration with Mitsubishi Electric Co. are summarized in this paper.

Method for the recording and reconstruction of 3D images of objects when using a so-called reference-free selectogram is suggested. According to this method, the light scattered by the object is filtered by a horizontal slit and is then split into two components with the help of a diffraction grating that is positioned just in front of a thick-layered photographic plate. The interference pattern that originates as a result of the interaction of the components formed by the diffraction grating is recorded in a light-sensitive material in a form of a 3D deep hologram. The reconstruction of the selectogram is performed by the light scattered by a diffusing screen that is positioned in a so-called window of the system. The analysis of the processes of the selectogram recording and reconstruction in a coherent and noncoherent light is carried out and some properties of the reconstructed image are considered. It is also shown that the structure of the 3D hologram recorded by the system does not practically depend on the wavelength of the recording light. The advantages of the reference-free selectogram are low requirements as to the coherence of the recording and reconstructing light and the insensitivity to the vibrations of the setup during the recording.

The results on the experiments on recording reference-free selectograms that reconstruct 3D images of objects are given. The selectograms were recorded by splitting the radiation of the object into two identical components with the help of diffraction gratings placed in front of a light-sensitive layer. The recording was performed on thin-layered inclined light-sensitive plates by using the method of pseudodeep holograms. The possibilities of recording reference- free selectograms of such a kind by a coherent radiation as well as by the radiation with a restricted spatial coherence were studied. In the case for which the selectogram was recorded by a coherent radiation, the radiation scattered by the object was split into two components by a diffraction grating placed in front of an inclined light-sensitive plate. The selectograms recorded in such a way reconstructed the volume images of objects whose resolution was sufficient for visual perception. For recording in an incoherent radiation an interferometer was suggested that was composed of two diffraction gratings which shifts the plane of the zero path difference of interfering beams into the center of the inclined photographic plate. The restriction of the coherence of the beam illuminating the object was performed by moving a diffusor that was used for illuminating the object-transparency. The selectogram recorded in such a way reconstructed the image being in a form of a luminous horizontal stripe corresponding to one of the horizontal cross-sections of the object being recorded. The experiment on the multiple recording of selectograms on one photographic plate at the successive displacement of the interferometer along the optical axis of the system has been carried out. In this case, the reconstructed image represented a system of horizontal luminous stripes each of them representing one of the lines of the image of the recorded object.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Two types of holographic 3D imaging systems are considered. The first one is based on a so-called selectrogram, i.e., the structure that can be registered by using the light scattered by the object as a reference one. The distance to the object is not limited in this case because it does not effect the capability of the light scattered by the object to interfere with itself. Two methods that permit us to increase the diffraction efficiency of the selectogram are discussed and investigated. The first one involves the focusing of the image of the object in the region located near the surface of the selectogram. Special convenience of this method is that it is also accompanied by the increase of the candlepower of the optical system at the stage of the selectrogram recording. The second method to enhance the diffraction efficiency of the selectrogram involves the increase of the real physical depth of the recording by increasing the inclination of the rays that intersect the holographic layer. The Dupont photopolymer films that were sealed between two glass prisms with the help of immersion were used for the recording in this case. As a result of simultaneous applications of these methods, the brightness of the image reconstructed by the selectrogram became comparable with that of the image reconstructed by the hologram. The second type of a 3D imaging system being considered is designed for the recording of 3D holographic copies of small valuable objects. The parameters of this system are strongly influenced by the phenomenon of the shrinkage of the light-sensitive layer of the photographic plate. This phenomenon was eliminated by using photopolymer light- sensitive layers for the hologram recording.

A key element of the optical image processing system is an image memory to temporarily store a huge amount of information between processing. Attempts have been made to use a silver halide photographic plate, a non-linear photorefractive crystal, a liquid crystal display and other elements as the image memory. However, none of these elements has proved satisfactory with respect to the following criteria: write and erase by an electrical method, signal-to-noise ratio of stored images, size of memory area and optical resolution. A thermoplastic photographic plate (TPP), in view ofits advantages oflarge memory capacity and ability to write and erase electrically, has been used for real time holography. However, the TPP is subject to the drawback of a high signal-to-noise ratio and has not been suitable for the image memory of the optical image processing. Recently, the authors conceived three methods to eliminate the drawback, and applied the TPP to holographic defect detection in periodic patterns. The TPP was used as the image memory and defect images were separated by spatial filtering and holographic optical image processing. Our results showed that 0.09 pm defects can be detected with signal-to-noise ratio 3.

Using the rainbow effect produced by employing a white light source in the reconstruction step of an image hologram, it is possible to obtain colored two-dimensional images. In this work a holographic technique to obtain pseudocolored schlieren images is proposed. The method is based on recording three image holograms consecutively on the same photographic plate using a He-Ne laser and three different reference beams, each one with a different angle with respect to the axis of the optical system. Each image hologram is recorded with a different position of the knife-edge into a conventional schlieren system. The multiplexed image hologram thus obtained gives different color information which is associated with the phase variations of the object under test, when it is illuminated by a conventional white light source, in the reconstruction step. Comparing this work with the conventional color schlieren system, color filters are not necessary and the images obtained can have good contrast and bright colors. Experimental results are shown.

Considered within the limits of paraxial off-axis approximation is the image calculation technique where the image is reconstructed by the reflection hologram taking into account the position of the point of observation. Shown is the effect of the size of the eye pupil and its position on distortions of the reconstructed image of the standard object. 1. CALCULATION OF IMAGE POSITION In the known papers devoted to the hologram recording and reconst ruction geometryi2 the coordinates of the image point are determined from the known coordinates of the object point reference and reconstructing sources. This approach however does not account for the well known experimental fact i. e. the dependence of the image posit ion and form on the observer''s position. Let us consider an ordinary case of recording and unconjugate reconstruction of the hologram of a point object. When a photographic plate is illuminated with coherent light from a reference source and point object an elementary hologram with a definite geometry will be recorded in each element of its surface with respect to the angles of incidence of the reference and object beams. When reconstructing the obtained hologram with unconjugate source each element of the hologram will reconstruct its image and the summary image reconstructed by the whole hologram will take the finite region in space. Fig. l shows the images calculated for four points of the hologram under the conditions: y0 cm z0 cm RR cm R56 Rc2O cm ac560. Let us determine which image can be seen when observing from point N located in axis Z with coordinate zN cm. Taking into account the direction of the elementary reconstructed beams following from the hologram we may be sure that only one elementary beam emerging from the hologram region close to the estimated point 3 passes through the point of observation. The other elementary beams forming the image run in different directions and do not pass through point N. When observing from the point with coordinate ZN cm the image of point 4 can only be seen and with ZN being less than 9 cm the image will not be seen at all if the hologram size equals 12 cm. The given example reaffirms the need for obligatory account of the observer''s position when calculating the image reconstructed by the hologram. 62 / SPIE Vol. 1238 Three-Dimensional Holography: Science Culture Education (1989)

A new method of holographic recording in the form of a thin laser beam which moves consecutively parallel to itself is being discussed which gives the scanning of all the space which is being holographed (object+hologram). Such a recording has been experimentally carried out in a single-beam scheme after the method of reflective holography and the technique of receiving large- sized holograms of scenes of a sufficiently large size has been improved. The production of higheffective reflective holograms on bihromate gelatine has been discussed a new technology of heat treatment has been proposed and an experimental check has been carried out. Gabor studying the ways which help us to improve the resolving power of an electron microscope created a new holographic method of an optical image. In particular while illuminating an object by a coherent light wave (the greatest part of'' the wave Is supposed to penetrate the object without disturbance) the diffraction image formed as a result of the secondary wave interference which appear in the presence of an object with a strong reference wave is recorded on a photographic plate. The reference wave transforms phase differences into intensity differences that is the phase turns out to be encoded in the quantity which is recorded on a photographic plate. In 1962W 1964 E. Leit and U. Upatnieks substantially improved Gabor''s method by using2 a laser and the off-axis recording scheme.

Renesse and Bouts represented the phase variations of holograms formed by conventional bleaches in which the hologram is bleached after development and fixing as a function of original density. They showed that the phase variations are determined mainly by the volume of the molecules of silver halide formed in the bleach bath. They formulated the nuer of silver halide as function of the original density.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The paper presents a new technique of quantitative performing of kinoforms. During preparing the kinoform a photochemical operations have been used. The phase retardation in each zone is controlled by a new diffraction technique. A standard photographic plate glass substrate is sufficient for described method.

From Gabor's concept of information and Shannon's discrete channel, the capacity of an optical spatialchannel is calculated. We have illustrated two basic spatially image encoding processes; namely, the en-coding over a set of uniform resolution cells, and over a set of nonuniform resolution cells. One of theimportant results is that the most efficient image encoding is the one that provides the most probable en-coded irradiance distribution over the spatial channel.IntroductionLet H be the average information provided per unit resolution cell of an optical source, and the sourceis emitting at a rate of m unit cells per second. Then the rate of information emitted by the optical sourse is(1) I = mH bits per second. (1) However, in most of the optical information sources there is some degree of temporal and spatial redun- dancy. To reduce this redundancy it is convenient to replace the source with a different set of image codes.The technique of performing the image coding transformation is through an encoding process. If the decodingprocess, at the receiving end, is assumed to be a unique process, then the encoding and decoding processwill result in no loss of information.Optical Spatial ChannelIn general an optical system can be treated as a spatial and time variable channel, that is, it can bedescribed by a function of a spatial domain and varies with respect to time; f(x,y;t), where x and y are theorthogonal spatial coordinates.It is assumed that the encoded image to be transmitted through an optical spatial channel or to be re-corded on a photo -sensitive plate (e.g., photographic plate). We would search for the smallest spatialbandwidth Ap of the optical channel so that the image to be transmitted through the channel with a minimumresolution element Ax is

A 700 -mm f/4.7 spectrograph camera lens was designed for imaging spectral lines in the200- to 400 -nm region on a 120 -mm flat image field. Lens elements of fused silica andcrystalline calcium fluoride have so little secondary spectrum that raytracing calculationspredict a monochromatic resolution limit of 30 lines /mm without refocusing in the 238- to 365 -nm region. Light scattering at the polished calcium -fluoride surfaces is avoided bysandwiching the fluoride elements between fused silica and cementing with silicone fluid.The constructed lens makes good spectrograms.IntroductionThe ultraviolet spectrograph lens to be described was designed to re$lace the visible -light camera lens in the Los Alamos MOD -40 Sweeping Image Spectrograph, which sweeps veryshort spectral lines along the film to get data for the study of rapidly changing events.The problem was to design a lens that would focus light in the 200- to 400 -nm region witha resolution of about 15 lines /mm and good contrast throughout the 10- degree image fieldneeded for recording on a 102- by 127 -mm photographic plate. For wide ranging surveys, thecorrection of longitudinal chromatism should be so complete that, without refocusing, thedesired resolution would be obtained for all wavelengths at all parts of the image field.However, complete adherence to this difficult performance specification is not essentialbecause recording at the optimum focus is usual when studying a particular spectral line.Fortunately, the lens- design calculations indicate that most of the desired performancewill be obtained without refocusing. The first test films show sharp recordings of afew mercury lines, thus leading to the expectation that the desired performance will beachieved. Because quantitative evaluations are not yet available, we can only say thatperformance of the new lens seems to exceed the 10- line /mm photographic resolution thatwas obtained with the visible -light lens, which was a quadruplet made with ordinary opticalglasses for imaging in the 400- to 700 -nm region.DiscussionThere were several problems to be overcome before a successful special -purpose ultravioletlens could be constructed. The first problem was the discovery of optical glasses with goodlight transmission when a 200 -mm thickness is used in the 200- to 400 -nm spectral region.The large thickness is needed for construction of the large camera lens, an objective lens,and an explosion -proof window. The glasses must have dispersion characteristics suitablefor use as crown and flint glasses. Fortunately, these glasses had already been discoveredby earlier workers. Large artificially -grown single crystals of optical -grade calciumfluoride are available for use as the crown elements. Ultraviolet -grade optical fusedsilica is available for use as flint elements and windows.The second problem is the relatively poor polish taken by the soft crystalline calciumfluoride. When this lens design was initiated in 1977, the residual roughness of the bestavailable polished surface scattered enough light to degrade the image contrast an intoler-able amount. To overcome this difficulty, the fluoride elements were cemented betweenfused silica elements. To eliminate the light scattering by surface roughness, the opticalcoupling compound used as a cementing agent must have a refractive index close to that ofcalcium fluoride. Also, it must transmit the light efficiently and remain pliable duringthermal expansion changes. The lengthy search for a suitable cement turned up siliconefluid (20,000 centistoke viscosity), which has very good transmission to 200 nm when usedin thin films, is quite inert, has a very low evaporation rate at room temperature, andfreezes at a low temperature. Although the polish now available on calcium fluoride is muchbetter than formerly, lens redesign is not justified because it is not known how much thelight scattered at the air -fluoride surfaces will degrade image contrast.The third problem is the procurement of an antireflection coating that has low reflectionand high transmission characteristics in the 200- to 400 -nm region. To obtain good durabil-ity and wide -band antireflection characteristics, a multilayer coating is probably needed.Unfortunately, an effective antireflection coating for such a wide region does not seem tobe available. However, the uncoated lens makes satisfactory images.

A sensitometer has been commissioned for the photometric calibration of spectroscopicand wide field astronomical plates. A set of illuminated apertures of various diametersilluminate a corresponding set of apertures all of equal diameter located immediately infront of emulsions. Twenty calibration spots in irradiance steps of 1.27 are exposed on toeach plate. Burr -free apertures of precise diameter were photo- etched in thin foil.During periodic calibrations, a fibre -optic feed system is coupled to a photon countingphotomultiplier. The instrument is spectrally neutral and spot irradiance ratios arecalibrated to within 1 %.IntroductionThe photographic plate is still the most widely used detector in astronomy. One obviousdisadvantage of this method of detection is the non -linear relationship which existsbetween exposure and the optical transmission of the processed plate. The relationshipvaries with plate type, spectral content and duration of the exposing radiation, platehistory (age, storage conditions) and processing procedure. In short, every plate has tobe separately calibrated in most astronomical applications and sensitometers - theinstruments used for plate calibration - are to be found in most observatories and photo-graphic laboratories.The simplest type of calibration can be obtained from the exposure of a step filter ortablet onto the emulsion; a method described in most photographic textbooks'. The stepfilter consists usually of a glass substrate onto which strips of thin metallic films ofvarious transmissions are deposited side by side. This composite filter is placed close toor in contact with the emulsion and an exposure made through the filter. Subsequent densi-tometry of the processed emulsion and a knowledge of the filter transmissions enables acalibration curve to be drawn. This type of sensitometer suffers from several problems.The proximity of the filter to the plate emulsion gives rise to inter -reflections whichvary from plate to plate and cannot be easily simulated in filter calibrations. Themetallic thin films are not spectrally neutral in their optical properties and probablyage, again making filter calibration difficult. The difference between specular densityand diffuse density of filters requires that the mode of illumination during calibrationshould be the same as that during sensitometer usage. Thus although simple to use, thistype of sensitometer is difficult to calibrate precisely.A modification of the above principle is to image an illuminated step filter onto theemulsions. This system overcomes the inter -reflection problem. Also in astronomy thistype of system can be incorporated into a telescope' so that the astronomical and sensito-meter exposures occur simultaneously and are of equal duration; a desirable feature becauseof the dependence of emulsion response to different environments; namely temperature andhumidity. Bench type projection sensitometers have also been made'.For a number of years a simple step filter sensitometer has been in use at theUniversity Observatory, St Andrews, and in spite of careful calibrations the disadvantagesmentioned made it desirable for a more reliable instrument to be built. The instrument wasused on the bench for calibrating direct image plates obtained with a 37 -inch Cassegrain-Schmidt telescope. More recently a spectrograph using photographic detection has beencommissioned and used on a 20 -inch telescope at the University Observatory. Although mostobservations with the spectrograph have been for the measurement of radial velocities whichdoes not require precise sensitometry, it is desirable to calibrate the plates for otherpossible future use. In common with other observatories, plates are normally hypersensi-tised prior to exposure and a convenient sensitometer was required for use in the optimi-sation procedures for different plate types and batches. The sensitometer therefore had tobe adaptable to suit different plate sizes and because of its multiple role, a benchmounted instrument was necessary.Many different systems4 were considered but a spot sensitometer based on sound geometri-cal design principles was eventually chosen and the experiences and suggestions of otherworkers with similar instruments were used to define the detailed design.

A. square-array of holes forming a sampling screen is used to test the 3.2 m paraboloid primary for the Infrared. Telescope Facility that is to be installed at Mauna Kea on the island of Hawaii. A point source is used to illuminate the mirror through the screen, and the reflected light is recorded on a photographic plate. The data obtained. from measuring the spot locations on the plate are reduced to obtain surface departures from a desired surface. The data reduction is performed with the use of two different computer programs, one which uses trapezoidal, and another which uses spline-function integrations in order to obtain. the surface departures, given surface slope values obtained from the measured spot locations. Also considered is the effect of the number of holes used in the surface sampling compared to the method of analysis.

The Steward Observatory of the University of Arizona employs short optical fiber lengths to bring light from galaxy images at the 2.3 m telescope's focus to a line along a spectrograph slit, thereby obtaining simultaneous spectra of many objects of the field of view. After describing this instrument, attention is given to the development of an improved version through which efficiency gains will be obtained by remotely positioning the fibers under computer control and by correctly matching fiber outputs to the spectrograph optics. A CCD will replace the presently employed image tube and photographic plate detector system, in order to permit sky subtraction, yield increased dynamic range, and provide more accurate wavelength calibration due to the detector's fixed format.

K. Aa. Strand U. S. Naval Observatory Washington, D. C.Astrometry deals with the space-time behavior of celestial bodies. Important areas within this classical field of astronomy include the determination of stellar distances and motions, studies of star clusters, and construction of photographic star catalogs.Since the turn of the century these studies have been carried out by means of photography with telescopes of high optical and mechanical stability over periods of time measured in major fractions of a century.The major portion of this work has been carried out with long-focus refracting telescopes, considered optically more stable than the reflecting type telescopes.The first reflecting type telescope specifically designed for astrometric work was placed in operation at the U. S. Naval Observatory (USNO) Flagstaff Station, Flag­ staff, Arizona in 1964. The design and operating procedures of the 61-inch (155 cm) astrometric reflector have been described elsewhere (Ref. 1, 2). More than 10 years of operation have proved that the telescope has not only met, but exceeded, the optical stability of the long-focus refractors.In order to attain the maximum accuracy from the photographic material obtained with the telescope an automatic measuring machine was acquired in 1966.Built by Nuclear Research Instruments in Berkeley, California, and based upon design specifications by the USNO, the machine has over the past 8 years proved to be a reliable high speed measuring system, with which more than 50,000 plates have been measured.The following salient features have been incorporated into the machine:1. Automatic centering of images with an opto-mechanical scanner, with a disk with 24 slits rotating at 3600 RPM scanning at the rate of 1 jam in the plate scale in 1 n second.2. Moire fringe measuring system of x, y coordinates with a least count of 1 jim and recording of data on punched cards.3. Automatic prepositioning on selected images with input from punched cards.4. Image projection with 3X and 40X magnification on viewing screen in front of the control console.5. Easy access to the machine with features enabling rapid change over from plate to plate.main structural members of the machine itself are made of heavy granite as are the two carriages which carry the photographic plate over a 25 X cm area.As shown in Figure 1, the lower car­ riage rides over the base plate on eight lift air bearings (pressure 4.2 kg/cm2), and its motion is controlled by granite guideways mounted on the base plate. Guide air bearings maintain the linearity of the motion.The upper carriage (the stage) rests above the base on four lift air bearings (pressure 2.8 kg/cm2) and is held perpen­ dicular to the saddle by two guideways mounted on it, again using guide air bear­ ings moving against the granite guideways.17

We present an experiment based on speckle photography, to study the distribution of velocities in a fluidat a given instant. This technique is complementary to laser velocimetry (WV), in which the velocity ismeasured at a certain point of the fluid, as function of time. A section of the fluid is lit by a laserbeam widened in one direction by a cylindricai lens and an image of this section is formed on a photographic plate. When polystyrene balls are added to the fluid, the image of the section lit is speckled. The laserbeam is modulated so that the section of the fluid being studied is lit by two short pulses separated by aknown interval of time. The photographic plate thus records two speckles displaced from each other; thisdisplacement is variable in the plane of the photographic plate, because of the distribution of velocitiesin the lighted plane. An analysis of this photographic plate permits us to construct the map of velocitiesof the illuminated section of the fluid.The study of the measurement of velocities in fluids by diffusion of laser light has been greatly devel-oped in the last few years(l1 This light is diffused by particles of microscopic

The speckles of the image plane of an object are radially shifted and decorrelated when the object is axially translated . It will be shown that the radial shift of the corresponding speckles is removed when the pupil of the optical system is placed in the back focal plane of the imaging lens . A photographic plate twice exposed to the irradiance of image plane and laterally shifted between the exposures , exhibits , after processing , a system of Young's fringes in its Fourier plane . The contrast of these fringes , which represents the correlation degree of the recorded speckle patterns , is only a function of the relative value of the axial shift of the object in camparison with the depth of focus of the imaging lens . If the pupil of the optical system is placed in the plane of the imaging lens , the contrast of the fringes generated in the same way as above , depends on the maximum value of the radial shift suffered by the speckles with respect to their mean size in image plane .© (1978) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We have developed a spark-gap system which permits a Cranz-Schardin type camera to be used for the recording of high speed events. A Cranz-Schardin camera is a high speed photographic facility which consists of a multiple spark generator used as a short-duration light source, an optical system which gives multiple shadowgraphs of the object on a still photographic plate, and an electronic control unit which provides delays before and between successive frames. In applying the Cranz-Schardin method to recording light emitting high speed phenomena, a principal problem has been the lack of reliable intense light sources with very short radiating times and restricted radiating areas. At the same time it is desirable to increase the illumination power as far as possible.

A speckle-pattern image method is used to determine the inclination with regard to viewing direction of a diffusing plane surface. We recorded on a photographic plate a defocused double exposure image, illuminating along the viewing direction with two neighbouring wave-lengths. In the experiments we have used, too, diffusing plane dihedrons illuminated in this way. Good agreement with the equation founded is observed.© (1978) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Correlation between two speckle patterns obtained by successive exposures has been extensively studied by many researchers. The correlation coefficient is associated with the roughness of the measured surface, the angular offset of the incident beam between two exposures, and the diffraction distance from the rough surface ( or its image ) to the photographic plate. The correlation degree can be estimated by measuring the contrast of the Young's fringes, in turns, the fringe contrast is used for determining roughness of the measured surface. If the fringe contrast is high enough, the interfringe spacing can be measured, which contains a great deal of information about the surface displacement, the surface rotation and the phase distribution.

This method is a direct development method for achieving a solid state image pickup device with a high speed electronic shutter on itself. A field integrating time is divided into a useless integrating time and a useful integrating time. The shorter one is the useful integrating time, the faster one is the electronic shutter speed. The useless integrated charges are cleared by the "photographic plate" clearing method. This image pickup camera apparatus is a high speed image pickup camera apparatus having low or slight high frame frequency, short explosure. A clear, relatively still or very slowly spinning images can be obtained by adjusting the field frequency of the high speed pickup camera apparatus.

The beam of light emitted by a conven-tional pulse laser is a summation of a number of transverse and axial resonance frequency modes. This type of laser is not suitable for making holograms except with a very specific arrangement of the laser light, object, and photographic plate (Ref. 1-3). In this arrangement, the object is illuminated from behind. Thus, an observer looking through the hologram plate at the reconstructed image sees only the outline or shadow of the object. Obviously, this technique is inadequate when the observer desires to discern surface detail on the holographed object.

The intent of this paper is to present the photo graphic plate reduction procedures being used by ACIC for Project ANNA. The discussion includes a. description of the processes involved in the reduction of photographic plates of a flashing light satellite. These processes include locating the satellite flashed, identifying reference stars, measuring the plates, reducing time tapes and computing the ap parant. position of the satellite flashes.