Buchroeder, Richard A. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1971-07)
      The history of modern wide -field, high-speed catadioptric lenses is reviewed. One system comprising only spherical curves and representative of the current art for low-light-level systems is evaluated and used as a baseline design in a weight-reduction study. Five aspheric designs are computed and evaluated. It is found that the use of aspherics will permit weight reduction only in certain instances, i.e., if one element of an all-spherical design can be eliminated or if a fundamentally different configuration that is possible only with aspherics is substituted for the all-spherical configuration. Of these possibilities, the elimination of an element is the best replacement for the baseline design. The case of a highly constrained, purely refractive triplet is studied in some detail. Four designs are computed -from the all-spherical case to the most complex polynomial aspheric. It is found that, if only conic aspherics are employed, significant improvement can be obtained and the problems involved are sensibly the same as those in all-spherical designs. When complex aspherics are applied, the problem becomes surprisingly difficult, and there is some indication that a computer can deal with it better than can a human lens designer.

      Cuneo, William J. Jr. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1970-10-30)
      The atmospheric transmission and airlight in three spectral bands as a function of an angle off nadir were calculated from radiometric measurements with cameras and film for a particular solar irradiance and atmosphere; the sun zenith angle was 49 °, the airpaths were from 15,000 ft m.s.l. to the surface at 1,900 ft on a clear day in Tucson, Arizona, and the azimuth was into the sun. The three spectral bands had peak transmissions at 430 nm (blue), 530 nm (green), and 800 nm (infrared). The statistics derived from numerous measurements show that a standard deviation of 2% can be attained in the relative radiances read out of multiband photography obtained with calibrated cameras and processed with carefully controlled sensitometry. In the blue and green bands, the atmospheric effect on contrast as a function of an angle off nadir became statistically noticeable at about 35° and 50 °, respectively. The standard deviations of the relative radiances measured in the blue and green bands were 3% and 2 %, respectively. The effect in the infrared band probably became significant at even larger angles; greater inaccuracy in the infrared band data precludes a more definitive statement. Also presented is a solution for an optimum ratio of playback lamp luminances for false color recombinations in two bands.

      Frieden, B. Roy (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1967-06-16)
      This paper derives a method for digitally reconstructing any two-dimensional, partially coherent, polychromatic object from experimental knowledge of the image and point spread function. In the absence of noise, the reconstruction is perfect. The object must lie wholly within a known region of the object plane. The optics may be generally coated and tilted, and may be aberrated to any extent. As an illustration, the reconstruction process is applied to the problem of resolving double stars. The reconstruction scheme is also used to correct the output of a conventional spectrometer for instrument broadening, and to correct the output of a Fourier -transform spectroscope for finite extent of the interferogram. Practical use of the method requires the calculation of prolate spheroidal wavefunctions and eigenvalues. The effect of noise upon the accuracy of reconstruction is analytically computed. It is shown that periodic noise and piecewise-continuous noise both cause zero error at all points in the reconstruction, except at the sampling points, where the error is theoretically infinite. Bandwidth -limited noise is shown to be indistinguishable from the object.
    • Catalog of Emission Lines in Astrophysical Objects

      Meinel, Aden B.; Aveni, Anthony F.; Stockton, Martha W. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1969-03)
      This edition has been prepared in order to include more recent information than was available at the time of the first printing. New material is not incorporated into the text directly but is placed at the end of each table. It will be found on pages B-133, C-12, D-12, and E-8.
    • Chirped Pulses in Laser Amplifiers

      Gieszelmann, Edward L. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1973-06)
      This dissertation presents a theoretical investigation into the production, evolution, and asymptotic form of chirped pulses in homogeneously and inhomogeneously broadened laser amplifiers. Amplifier equations of motion are obtained in a form appropriate for dealing with such frequency-modulated pulses. The transient response of laser amplifiers to variously chirped Gaussian input pulses is studied parametrically using numerical solutions of the amplifier equations. The chirping mechanisms of the intensity dependence (Kerr effect) and the quadratic frequency dependence of the index of refraction are discussed briefly, as are the chirps produced by them and the amplification of Gaussian pulses in their presence. The amplifier whose host exhibits these dispersive effects is treated as a sequence of pairs of slices. One of each pair amplifies and exhibits the Kerr effect; the other has an index with a quadratic frequency dependence. This slice model is used to obtain steadystate pulses in both homogeneously and inhomogeneously broadened amplifiers whose host indexes have a quadratic frequency dependence. The steady-state pulse characteristics are determined as functions of amplifier parameters and the index curvature. The principal results are as follows: The homogeneously broadened amplifier responds predominately to the temporal character of a chirped input pulse whereas the inhomogeneously broadened amplifier response depends primarily upon the pulse spectrum. Of three important concepts (area theorem, echoes, and optical nutation) used to describe unchirped pulse amplification in inhomogeneously broadened media, only photon echo is useful when pulses are more than slightly chirped. The presence of the Kerr effect can produce significant chirps on large pulses. Amplification in the presence of the Kerr effect produces pulses strikingly similar to experimental results. Quadratic frequency dependence in the index has very little influence on most pulses in short amplifiers but has a cumulative effect in long amplifiers and laser oscillators. Chirped steady-state pulses exist in both homogeneously and inhomogeneously broadened amplifiers when the host index has such frequency dependence. In the homogeneously broadened case, they exist at relative gain levels dramatically below other theoretical predictions. They occur in the inhomogeneously broadened case only for the smaller index curvatures.

      Hooker, R. Brian (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1970-05-15)
      The optical performance of three stereomicroscopes commonly used for photo - interpretation is described in terms of magnification, field of view, and square wave response (SqWR). For a given field size, the SqWR can be used to compare the amount of information in the image of each microscope. The SqWR was determined by scanning a square wave test target at four field positions for each of four field sizes (corresponding to magnifications of 6, 12, 25, and 50X). The measured SqWR was used to evaluate the relative ability of each microscope to perform two typical photointerpretation tasks: (1) detailed viewing of a target, and (2) scanning or searching for a target. For these tasks the Wild M -5 stereomicroscope was found to be somewhat better than the Bausch and Lomb 240 stereomicroscope, and both were found to be superior to the Olympus SZ III stereomicroscope. The SqWR curves are included and can be used to compare the stereo - microscopes for various photointerpretation tasks.
    • Design Examples of Tilted-Component Telescopes (TCT's) (A Class of Unobscured Reflectors)

      Buchroeder, Richard A. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1971-05)
      A tilted component telescope (TCT) is one that features no obstructions in the light path yet is appreciably simpler to build than conventional off -axis instruments. The principles of TCT design are applicable to scanning and image-stabilized optics and should allow improvements in that field. The author has collected and computer-evaluated designs representative of existing art: Schiefspiegler, Yolo, catadioptric Herschelian, and Schupmann. It is expected that these evaluations will enable optical scientists to appraise the merits of the TCT approach and will stimulate the development of second -generation designs.

      Wilkerson, Gary W. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1970-03-15)
      This report presents the author's basic findings on various optical systems that he studied and /or designed at the Jet Propulsion Laboratory, Pasadena, California, for the high -resolution telescope of NASA's Mariner '69 and '71 television experiments. This f/2.5 508-mm-efl system had a 2° full field. Application of Burch's plate diagram was found useful in describing the research. Design work was done using the Los Alamos Scientific Laboratory lens design program, which meant using an rms spot size radius as the design criterion. The JPL requirement was a 40% modulation transfer factor at 80 Qp /mm, taking into account diffraction effects. Particular emphasis is placed on presenting computed and actual performance of the "long" one-conic "Equi -Radii Baker" telescope, which was chosen to fly by Mars in the Mariner VI and VII spacecraft. This system had the best resolution and lightest weight of any system optimized by the author but was also the longest system. It consisted of an aspheric plate for the window plus two mirrors of equal radius, the primary being an oblate spheroid and the secondary a sphere. The aspheric plate had to have the proper sphericity to introduce enough axial color to balance the large amount of spherochromatism occurring over the required spectral bandwidth.
    • Design Specifications for an 84 and 100-Inch Telescope

      Meinel, A. B. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1966)
      This technical report was prepared from the specifications document used for the bids for the University of Arizona telescope. This telescope was funded by the National Science Foundation under the Science Development Program. This document is being included in the Optical Sciences report series since it may have some relevance to the programs in this area.
    • The Design, Construction, and Testing of the Optics for a 147-cm-Aperture Telescope

      Buchroeder. R. A.; Elmore, L. H.; Shack, R. V.; Slater, P. N. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1972-12)
      In this report we describe the work carried out under contract F19628-72-C-0047 entitled "Geodetic Optics Research" for the Air Force Cambridge Research Laboratories (AFCRL). The work consisted mainly of the fabrication of the optical components for a telescope with a 152 cm-diam (60-in.) primary mirror masked down to 147-cm diam for use by the AFCRL for a lunar ranging experiment. Among the noteworthy achievements of this contract were the following: (a) Completion of the primary and secondary mirrors for a high -quality 147 -cm- diam telescope system in eight months from the start of edging the primary. (b) Manufacture and testing of a unique center mount for the primary according to an AFCRL design that allowed for a thin-edged and therefore less-massive mirror. (c) Development of a quantitative analysis of the wire test for calculating the departure of the mirror figure from the design figure quickly and accurately after each polishing step. This analysis method in conjunction with a knowledge of polishing rates for given weights and diameters of tools, mirror, and polishing materials should considerably reduce the polishing time required for future large mirrors. The emphasis in this report is on these three items; however, considerable work was also undertaken in telescope design; null lens design and mounting; tracking optics design, fabrication, and mounting; and special thin -film coatings for the laser send and receive optics.

      Wheeler, L.; Daniel, T.; Seeley, G.; Swindell, W. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1971-12)
      We report here the first experiments in a long-range program for investigating the effectiveness of image-retrieval or image-enhancement procedures. We employed a signal-detection mode of observer response, and our stimuli were computer-generated, pointed, abstract forms that we call quadrigons. Four values of signal-to-noise ratio were provided by varying the amount of roundedness of the interior and exterior angles of these forms. Linear blur, grain magnification, and figure-surround contrast ratio were the other independent variables in our factorial design. For each quadrigon, observers gave scaled expressions of confidence that the photographed object was originally pointed (the "signal present" condition). Scores from 12 observers, who were each exposed twice to a set of 500 quadrigons, yielded receiver operating characteristics (ROC functions) that are sensitive, quantitative indicators of the discriminabilities of the stimuli. By this method, also, an observer's criterion state (his degree of willingness to guess that a signal was present) was evaluated and removed as a contaminating factor. Signal-to-noise ratio had a strong and systematic effect upon signal detection accuracy when the effects of all other variables were combined. Linear blur, grain size, and contrast ratio each affected observer performance greatly. All two-way, three-way, and four-way interactions among the independent variables were highly significant; each source of image degradation had differential effects upon every other variable, and combinations of the variables had additional effects. The results are complex, but they provide useful implications for image processing that is designed to enhance information retrieval. We can, for instance, define the effects upon signal detectability when linear blur is reduced by specified amounts, or grain size is reduced, or contrast conditions are improved. We can, moreover, specify certain optimum combinations of values for these variables.

      Mahajan, Virendra N. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1974-06)
      Diffraction of light by a sinusoidal sound wave is discussed in detail. Assuming that the sound column modulates only the phase of the incident light in both time and space, the frequencies, wavevectors, and intensities of the diffracted waves are obtained for normal incidence. A transition length (width of sound beam) is defined, above which all diffraction effects disappear due to destructive interference. Constructive interference is obtained, however, provided the light is incident at the Bragg angle, in which case the diffracted beam appears to be reflected from the acoustic wavefronts. The transition length thus separates the region of multiple -order (Raman -Nath) diffraction from the region of single -order (Bragg) diffraction. It is found to be directly proportional to the square of the acoustic wavelength and inversely proportional to the optical wavelength. In the case of Bragg diffraction, the energy is exchanged sinusoidally between the diffracted and undiffracted beams. Owing to the finite width of the sound beam, the Bragg condition is relaxed, and the effect can be used to control the direction and phase of the diffracted beam or to determine the angular distribution of the acoustic power. Next, a particle picture of diffraction in terms of photons and phonons is given. The diffraction process is described as a single as well as a multiple three -particle interaction. The effects of finite optical and acoustic beamwidths and variation of acoustic frequency are considered in terms of momentum conservation. Finally, an analysis based on Maxwell's equations for an arbitrarily polarized light beam propagating in an arbitrary direction is given using the partial -wave approach. A set of coupled difference- differential equations for the diffracted amplitudes is derived from the optical wave equation and analytic solutions are obtained in the Raman-Nath and Bragg regions of diffraction. The results for normal and Bragg incidence are obtained as special cases. Limits of the two regions are defined, thus giving a transition region in which numerical solutions can be obtained.

      Malvick, Allan J. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1968-08-15)
      The tensor equations of elasticity in nonorthogonal curvilinear coordinates are presented in a form suitable for the method of dynamic relaxation. This method is described briefly and then is applied to the solution of the problem of elastic deformation of curved mirrors.

      Baker, L. Ralph; Slater, Philip N. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1970-05-01)
      Multiband photography has been employed for several years as a tool for aerial reconnaissance. Recent experiments indicate a potential value in earth resources studies, particularly those utilizing an electro-optical image sensor. This report lists the imaging properties of an electro-optical multiband camera that uses one combined image tube /camera tube sensor to achieve high- quality imagery with maximum registration between separation images. A study was made to determine which camera tube would be the best choice for the earth resources program. The results of the study indicate the best choice is a standard vidicon with fiber optic faceplate coupled to an image intensifier with an extended red photocathode. This decision was based on lifetime, image quality, ruggedization, and cost criteria.

      Baker, L. Ralph (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1970-12-10)
      Multiband photography has been used for several years as a tool for aerial reconnaissance. Recent experiments indicate a potential value in earth resources studies, particularly those utilizing an electro-optical image sensor. This report summarizes the test parameters and testing philosophy of several electro-optical devices. The results of camera tube testing indicate that vidicons similar to the RCA 4589 are suitable for a multiband electro-optical camera system. Results of image tube testing indicate that careful specifying of imaging performance is necessary, and results of coupled camera tube /image tube testing indicate that improvement is necessary for coupling the fiber optics. It is recommended that the vidicon be used at rather high dark current (~100 nA) and that dark current subtraction be employed for the flight program.

      Seeley, G. W.; Yee, B.; Wheeler, L. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1975-10)
      The problem: to what extent do cortical evoked potentials correlate with differences in complex visual stimuli and with differences in observer confidence that a correct judgment has been made? Electroencephalographic records obtained in response to complex visual stimuli were examined in two studies involving thousands of stimulus presentations and a variety of stimulus characteristics. Six observers made responses to subsets of the stimuli. A signal detection paradigm governed the experimental procedures and analyses. Even when stimulus differences were extremely small, it was often possible to make accurate assignments of sets of averaged EEG's to the appropriate stimulus conditions and to an observer's degree of confidence in the correctness of his judgment.
    • Evaluation of Image Intensifier Tubes Using Detective Quantum Efficiency

      Smith, Gregory H. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1972-07)
      In recent years, many new image detectors have been developed that are sensitive to extremely low light levels. These devices have given new importance to a performance criterion called detective quantum efficiency, or DQE. The subject of this investigation is to develop the basic experimental technology necessary to measure DQE of image detectors, and to apply these techniques specifically to photographically recorded image intensifiers and to unaided photographic emulsions. DQE is defined as the square of the ratio of output S/N to input S /N. Input S/N is determined by the input photon statistics. Output S/N is determined by measuring the recorded image. Two ways of measuring DQE are the single-level gradient method and the two-level AD method. The AD method gives a more appropriate measure of the performance of image intensifiers that have light- induced background. A special two -channel projector was built to measure DQE by the AD method. Its function is to superimpose the image of a signal target upon a uniform background irradiance. The same instrument can be used to obtain DQE measurements using the gradient method. DQE was measured for two image intensifiers (a high -gain TSE tube, model P829D, made by EEV, and a two -stage cascade intensifier, model C3301 1, a Carnegie tube made by RCA) and two unaided photographic emulsions (Kodak IIa -O and Kodak Medium Contrast Projector Slide). The results show that different image detectors may have considerably different DQE performance. For example, at 425 nm, DQE values for the Carnegie tube were more than 20% (the quantum efficiency of the input photocathode is 28 %) whereas both of the unaided photo- graphic emulsions gave peak DQE values no greater than 0.8 %. In addition, the peak DQE of the Carnegie tube occurred at roughly 10' photons /cm2 whereas the peak DQE of unaided IIa-O occurred at 109 photons /cm2 (both at 425 nm). Furthermore, single photon event detectors (such as high -gain image intensifiers) have a peak DQE near zero exposure with DQE decreasing as exposure increases whereas multiple photon event detectors (such as unaided photographic emulsions) have zero DQE near zero exposure, a peak DQE at an exposure which yields a corresponding output density of about 0.2 above fog, and a decreasing DQE for further exposure increases. Also measured were granularity, light- induced background, system modulation transfer functions, and relative system speeds.

      Cromwell, R. H. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1969-04-25)
      A brief description is given of the various types of image tubes presently used in astronomical research and a review is presented of the past applications of image tubes to direct astronomical photography. A detailed laboratory evaluation of the Carnegie image tube is summarized and photographs at the telescope are presented to confirm and extend the results obtained in the laboratory. Iris photometry of stellar images can be carried out on Carnegie tube photographs with about the same accuracy as is obtained by normal photographic techniques. Compared to unaided plates the image tube typically requires about 1/15 the exposure time to record stellar images of a specified threshold magnitude. When exposures are made to near the sky limit, however, the Carnegie tube cannot record stars as faint as can be recorded with an unaided plate. When exposed at a given focal length telescope, the limiting magnitude of an image tube record is about 1 magnitude brighter than that of an unaided photograph. Primarily two characteristics of the Carnegie tube, an over-all mottled sensitivity pattern and a light- induced background, are found to be responsible for the loss in limiting magnitude of a Carnegie tube record. The mottle pattern is characterized by an rms variation in sensitivity of ±1.3 percent. It modulates the photographic record of the night-sky radiation and seriously affects the signal -to -noise ratio of the threshold images. The additional background produced by the light- induced background of the image tube generally amounts to 25 percent of the night-sky radiation on a sky-limited photograph. In order to record the same sky-limited magnitude on a Carnegie tube plate and an unaided plate, the image tube record must be exposed at a longer focal length telescope. The exposure time required by the image tube is then about 1/2 to 1/3 that of the unaided plate. Because of the higher scale of the image tube photograph in such a case, however, the effective gain provided by the image tube over the unaided plate is generally somewhat larger than the relative exposure time. The photography of extended objects is found to be particularly affected by the nonuniformities of the image tube. Besides reducing the over-all signal-to-noise ratio of the image tube record, the generalmottle pattern and additional discrete patches and ripples in sensitivity of the image tube tend to mimic low contrast features of galaxies and nebulae. The rather subjective effects of the nonuniformities can be significantly reduced by using telescopes with moderately long focal lengths, so that the seeing image is then large in comparison to the nonuniformities. The photography of astronomical sources through narrowband interference filters has been found to be a particularly promising application of the Carnegie image tube. Preliminary tests reported in the present study include the photography of supernova remnants, planetary nebulae, galaxies, and reflection nebulae. The basic quality criterion for comparing the image tube to unaided photographic emulsions is argued to be the detective quantum efficiency. Typical values of the gain over unaided emulsions provided by the Carnegie tube are calculated to be in the range 10 to 20. It is emphasized, however, that because of the variety of requirements in specific research areas and because of the several unique characteristics of a given image tube, no single figure of merit may be defined that will predict the usefulness of an image tube in all applications. It is suggested that the resolution of a detector should not generally be combined into the calculation of a single figure of merit but should be considered as a separate quality criterion. Certain problems with the Carnegie tube (and other image tubes as well) potentially limit its usefulness in specific research areas. Besides the problems already mentioned, other problems include low resolution, geometrical distortion, the complexities of analyzing the final record (as compared to an unaided photograph), and the limited field of the image tube. Each of these characteristics can be highly significant or entirely inconsequential in different applications.

      Frieden, B. Roy (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1969-07-01)
      A function PvN(ß) exists whose finite Fourier transform over a specified range of its argument is asymptotic (with N) to an Airy distribution with arbitrary scale compression. Consequently, when the function is applied as a passive coating to a diffraction -limited lens of fixed aperture,the point amplitude response collapses inward as if the lens were physically replaced by a diffraction-limited lens of greater aperture. Investigating the implications of coating PN(ß) to image theory, we find the following: (1) The scalar wave equation has intrinsically a particlelike solution. (2) A modification of PN(ß) causes an arbitrarily narrow depth of focus. (3) An arbitrary point amplitude response may be optically produced. (Suppose g(x) to be a required, and arbitrary, point response function with G(ß) its finite Fourier transform. Then pupil PN(ß)G(ß) produces g(x), asymptotic with N.) (4) When applied onto any band -limited pupil G(ß), coating PN(ß) effectively extrapolates G(ß) arbitrarily beyond the bounds of the aperture. Some amusing analog devices, based on the extrapolating property (No. 4 above), are next developed. These are an optical analog signal extrapolator, a picture extrapolator, and an analog method of band -unlimited image processing. We also suggest the existence of a laser "superposition mode" whose out- put would be arbitrarily directive, and the possibility of using an acoustical pupil NO) to resolve these long wavelengths with near-optical quality. The ultimate limitations on the practical use and fabrication of pupil PN(ß) are discussed.
    • An F/2 Focal Reducer For The 60-Inch U.S. Naval Observatory Telescope

      Meinel, Aden B.; Wilkerson, Gary W. (Optical Sciences Center, University of Arizona (Tucson, Arizona), 1968-02-28)
      The Meinel Reducing Camera for the U. S. Naval Observatory's 60-inch telescope, Flagstaff, Arizona, comprises an f /10 collimator designed by Meinel and Wilkerson, and a Leica 50-mm f/2 Summicron camera lens. The collimator consists of a thick, 5-inch field lens located close to the focal plane of the telescope, plus four additional elements extending toward the camera. The collimator has an efl of 10 inches, yielding a 1-inch exit pupil that coincides with the camera's entrance pupil, 1.558 inches beyond the final surface of the collimator. There is room between the facing lenses of the collimator and camera to place filters and a grating. The collimated light here is the best possible situation for interference filters. Problems of the collimator design work included astigmatism due to the stop's being so far outside the collimator, and field curvature. Two computer programs were used in development of the collimator design. Initial work, begun in 1964, was with the University of Rochester's ORDEALS program (this was the first time the authors had used such a program) and was continued through July, 1965. Development subsequently was continued and completed on the Los Alamos Scientific Laboratory's program, LASL. The final design, completed January 24, 1966, was evaluated with ORDEALS. This project gave a good opportunity to compare ORDEALS, an "aberration" program, with LASL, a "ray deviation" program. It was felt that LASL was the superior program in this case, and some experimental runs beginning with flat slabs of glass indicated that it could have been used for the entire development of the collimator. Calculated optical performance of the design indicated that the reducing camera should be "seeing limited" for most work. Some astigmatism was apparent, but the amount did not turn out to be harmful in actual astronomical use. After the final design was arrived at, minor changes were made to accommodate actual glass indices of the final melt, and later to accommodate slight changes of radii and thicknesses of the elements as fabricated. An additional small change in spacing between two of the elements was made at the observatory after the reducing camera had been in use for a short time. The fabricated camera is working according to expectations. Some photographs are included in the report to illustrate its performance and utility.