STRAY LIGHT IN CZERNY-TURNER AND EBERT SPECTROMETERS

Stray light due to undesired multiple dispersions has been investigated for Czerny-Turner and Ebert grating spectrometers. Both double dispersion and higher multiple dispersions are discussed in all orders of diffraction. Experimental and theoretical results are presented. An upper bound on the wavelength of this stray light is found as a function of the grating spacing. This shows that over any wavelength range of interest, the stray light due to multiple dispersion often can be eliminated by use of sufficiently finely ruled gratings. The results are also used to propose improvements on a previously suggested [C. M. Penchina, Appl. Opt. 6,1029 (1967)] masking technique. © 1968 Optical Society of America.