Preston, Thomas, Joly, Charles Jasper, 1864-1906, Parsons, John Herbert, Sir, 1868-1957, donor, University College, London. Library Services · London : Macmillan and Co. · leaf 261
237 CURVED GRATINGS ART. 142 ruled be not plane, but have any curved section AB (Fig. 116) per- pendicular to the lines of the grating. If light from a source S fall upon it at an angle i with the normal, and be diffracted at an angle 6, … sides of the normal (as in Fig. 1 1 6). Fig- n^- To obtain the image S' of S, virtual or real, let us consider two rays SPS' and SQS' incident at angles i and i + di, and diffracted at 0 and B + dO respectively, and let the normals to the curve at P and Q meet at C. Denote the small angles at S, C,…
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