Interferometric Methods for the Photographic Production of Large Gratings

Abstract

The need for new types of coarse gratings for moiré fringe applications has aroused fresh interest in the possibility of using interferometry to generate gratings photographically. It is shown that this is now practical, and that certain commercially available emulsions have adequate resolving power and freedom from distortion. A large two-beam interferometer has been constructed which is capable of producing gratings with between 1000 and 5000 lines per inch with an aperture 18 in. in diameter. The design and adjustment of the instrument are described. Large gratings of 1150 l.p.i. have been produced, and their application to stellar spectroscopy is being investigated. It is hoped to make the fringe spacing continuously variable, and this will open up further spectroscopic possibilities on the lines suggested by Connes [1].