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Studies of Visual Telescope System Employing Reflection Optics Theodore Dunham, Jr. 1951 A subcommittee of the Committee on Vision undertook a study of the possible uses of optical systems for employing reflecting elements for visual applications by the Armed Forces in January 1950. Although particular attention was given to the telescopes recently developed by Dr. Bouwers and his group in Holland, a number of other designs were also studied. The group was reorganized in July 1950 as a working group. This report summarizes the studies done through February 1951 and includes recommendations for further work in this field. The basic principle of the reflecting systems discussed is based on the use of a concave spherical mirror to form an image, together with a meniscus lens with suitable thickness and surface curvatures to correct spherical aberration. A system of this type avoids the difficulty ordinarily encountered in forming, with sufficient accuracy for visual applications, an aspherical optical surface, such as is required for a Schmidt correcting plate to serve a similar purpose. Although a meniscus lens cannot provide quite as perfect correction on the axis as a Schmidt correcting plate, the extent of useful field of view is considerably greater. The use of a meniscus lens to correct the spherical aberration of a concave spherical mirror appears to have been invented independently by D.D. Maksutov in Russia, ~ Bouwers in Holland, D. Gabor in England, and H.F. Bennett in the United States. In October 1949, Dr. Bouwers visited this country and described to several groups including military rep- resentatives the developments that had been carried out in his laboratory. These included several types of reflecting monocular and binocular tele- scopes, microscopes, and cameras, all of which employ meniscus lenses in combination with one or two spherical mirrors. Many of these systems appear to have potentially attractive features, from the point of view of overall dimensions, weight, and simplicity of design. The group was asked to evaluate the relative advantages of instruments employing reflecting el- ements compared with comparable conventional refracting systems, giving particular attention to instruments intended for visual use. 51 pp. 38 figures 9 tables 14 references Availability: National Technical Information Service (NTIS), 5285 Port Royal Road, Springfield, VA 22161. 57
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Theory of Slant Visibility Leonard Foitzik 1952 The meteorological visual range represents an extraordinarily complex quantity. The definition of the visual range is not uniform. In this report, the visual range is defined as the distance at which the contrast between the target and its surroundings equals the threshold of contrast of the eye, i.e., the target lies just at the boundary of visibility. The parameters are partly determined by meteorological factors (state of turbidity along the pyramid of vision, conditions of illumination, cloudiness), partly by the target properties (position of target, size of target, reflectivity and color of the target). An additional portion of the parameters can be traced back to physiological properties of the eye (dependence of the threshold of contrast on the angular subtense of target, on the target brightness, and on the target shape.) In meteorology, and especially in synoptic meteorology, the visual range is of interest primarily because it characterizes the state of turbidity of the air layers near the surface. The Koschmieder theory of horizontal visual range is extended, at first, to inhomogeneous conditions of turbidity along the pyramid of vision, and a graphical method is presented for the determination of the visual range with any stratification of turbidity. A formula of visual range is derived for the case of a uniform decease in turbidity with maease in distance. In order to be able to apply this formula to the slant-visibility of aerial targets as observed from the ground, an extension of the formula is necessary for the consideration of the target size. A graphical method is described by means of which it is possible to determine the slant-range of a black aerial target for any target size and target altitude as well as for any condition of turbidity with uniform decrease in turbidity with altitude. Finally, a numerical survey of the magnitude of the slant-range of black aerial targets is presented in several tables. 22 pp. 10 figures 7 tables 7 references Availabilay: Committee on Vision, 2101 Constitution Ave., N.W., Wash- ington, D.C. 20418. 58
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A Bibliography on Reflecting Optics 1925-1950 . . Stanley S. Ballard 1950 (revised 1955) This bibliography on reflection optics would be useful to those working in a field of such increasing interest and importance. Special attention is given to technical papers that are relatively inaccessible because they appear in foreign publications or in journals of limited circulation. The bibliography contains 229 literature references and 58 patents. Very little material is dated prior to 1934. The best sources of references were Physics Abstracts and the footnote references found in some articles, but not, themselves, listed in the abstract journals. 2% pp. no figures no tables 287 entries Availability: National Technical Information Service (NTIS), 5285 Port Royal Road, Springfield, VA 22161. 59
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1962 Symposium on Physiological Optics 1962 This report, which appeared as a complete issue of the Journal of the Optical Society of America, includes the texts of many of the papers presented at the Optical Society's 1962 spring meeting. The meeting included sessions on the microanatomy and biochemistry of the visual system, the electrophysiology of the visual system, refined image formation, simple discriminatory functions, and contributions to color discrimination theory. The papers are as follows: "Structure and Molecular Organization of Retinal Photoreceptors," J.J. WoLken; "The Problem of Visual ~cita- tion," G. Wald et al.; "Cellular Physiology of the Retina," W.K Noell; "Electrical Activity in the Vertebrate Retina," T. Tomita; "Integrative Pro- cesses in Central Visual Pathways of the Cat," D.H. Hubel; "Functional Basis for 'On'-Center and 'Off'-Center Receptive Fields in the Retina," H.G. Wagner et aL; "Optical Properties of the Retinal Receptors," J.M. Enoch; "Optical and Motor Factors in the Formation of the Retinal Im- age," G. Westheimer; "Retinal Image Formation: Review, SummaIy, and Discussion," G.~ Fly; "Initial Stages of Dark and Light Adaptation," H.D. Baker; "Increment Threshold and Dark Adaptation," W.~H. Rushton; "Spatial and Temporal Aspects of Retinal Inhibitory Interaction," F. Ratliff et al.; "Fluctuation Theory of Luminance and Chromaticibr Discrimina- tion," M.^ Bouman; "Neural Theories of Simple Visual Discriminations," H.R. Blackwell; "Supple Discriminatory Functions: Review, Summary, and Discussion," C.H. Graham; "Contnbutions of Threshold Measurements to Color-Discrimination Theory," R.M. Boynton; "Studies of Anomalous Contrast and Assimilation," H. Helson; "Further Studies on Acquired Deficiency of Color Discrimination," G. Verriest, and "Contributions to Color-Discrimination Theory: Review, Summary, and Discussion," L.M. Hurvich. 201 pp. 316 figures 39 tables 739 references The Journal of He Optical Society of America VoL 53, No. 1, 1963. Availability: National Technical Information Service (NTIS), 5285 Port Royal Road, Spnngfield, VA 22161. 60
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Current Developments in Optics and Vision William Benson and Milton ~ Whitcomb, Editors 1968 This report describes the current developments in optics and vision un- der the following topics: Dynamic Parallax: Dynamic Visual Cues in Flying; Vision and Driving; Holography: Principles and Properties of Hologram Photography; Present and Future Applications of Holography; Scientific Applications of Holography; Image Restoration and Enhancement: The Elastic Surface Transformation; Image Processing as it Relates to the Hu- man System; Experiments in Spatial Filtering; Visual Factors Related to the Design and Use of Direct-View Electro-Optical Devices; The Influence of Spatial and Temporal Bandwidth on Threshold Contrast Sensitivity of the Eye; and Visual Detection of Oscilloscopic liacings. 128 pp. 44 figures 3 tables 113 references Availability: AD 673425, National Technical Information Service (NTIS), 5285 Port Royal Road, Springfield, VA 22161. 61
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