For two flatness requirements involved in the testing of air survey cameras special techniques have been devised.
Photographic plates used for camera calibration should be flat to one or two microns. To achieve this the plate glass supporting the emulsion is bent flat and held flat during exposure. Flatness is determined in an interferometer using infrared light.
Camera register glass flatness is also checked interferometrically. Since counts of over 100 fringes are required, two monochromatic light sources are used, chosen to produce regular arrangements of black and colored fringes which permit counting by groups.
© 1955 Optical Society of AmericaFull Article | PDF Article
OSA Recommended Articles
George R. Harrison and George W. Stroke
J. Opt. Soc. Am. 45(2) 112-121 (1955)
George W. Stroke
J. Opt. Soc. Am. 45(1) 30-35 (1955)
Vincent J. Coates and Harry Hausdorff
J. Opt. Soc. Am. 45(6) 425-430 (1955)