SUPERIMPOSED EQUALLY ORIENTED DIFFRACTION GRATINGS FORMED IN As2S3 FILMS

Surface relief diffraction structures composed of two or three superimposed unidirectional gratings with unequal grating periods were produced using the electron beam recording and subsequent chemical etching. Diffraction patterns produced by different diffraction structures were studied. In addition to the main diffracted beams the low-intensity "ghost" diffracted beams were created by some grating structures. Their appearance was caused by a difference in spatial frequency between gratings and by summation of spatial frequencies as well. The calculated grating periods corresponding to "ghost" diffracted beams were found to agree well with those determined from diffraction patterns.