Abstract
LONDON. Optical Society, Nov. 8.—T. Smith: (1) On systems of plane reflecting surfaces. An algebraic method is evolved of finding the co-ordinates of the image of any point and of the direction of the emergent portion of any given incident ray after reflection at any number of plane reflecting surfaces. Systems of reflectors are classified according to the nature of the self-conjugate region of the field. A method of designing a system having any assigned properties is described. Suitable criteria are given to determine whether with a prismatic system the whole is non-dispersive, and whether total internal reflection takes place at any given surface; also the boundary conditions at each surface are found. The calculations are simple and free from any ambiguity of sign.—(2) Reflecting systems for image inversion. The above method is applied to an inverting prism. Four surfaces involve oblique refraction into the prism whatever the number and order of the reflections. With five surfaces one form is possible with four reflections. All possible arrangements with six reflections at five surfaces are considered, and the application of the method to prisms with a greater number of reflections is illustrated.—L. C. Martin and T. C. Richards: The relations between field illumination and the optimum visual field for observational instruments. Experiments based on the application of the results of recent studies on spatial induction in vision to determine the conditions governing the optimum size of visual field under certain conditions are described. The results have a bearing on recent efforts to enlarge greatly the fields of view of binoculars, indicating that small fields are better under certain conditions.
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Societies and Academies. Nature 122, 908–911 (1928). https://doi.org/10.1038/122908a0
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DOI: https://doi.org/10.1038/122908a0