Method and device for separating diffracted light

TL;DR: In this paper, the authors proposed a method to easily separate diffracted light beams from diffraction gratings which are arranged nearby by converging or diverging a laser beam projected on the gratings by an exposure device which utilizes an optical heterodyne interference method.

Abstract: PURPOSE:To easily separate diffracted light beams from diffraction gratings which are arranged nearby by converging or diverging a laser beam projected on the diffraction gratings by an exposure device which utilizes an optical heterodyne interference method CONSTITUTION:A laser beam outputted by a two-wavelength orthogonal polarized light laser beam source 1 is passed through a cylindrical lens 3 to become an elliptic beam, which is split by a polarization beam splitter 4 into beams which differ in wavelength and are made incident on mirrors 5a and 5b Condenser lenses 31a and 31b are arranged in front of reflection type diffraction gratings 7 and 9, so the incident beam 31 and 33 incident on the diffraction gratings 7 and 9 are divergent beams Consequently, the diffracted beam 34 and 35 from the gratings are divergent beams, which are separated as they leave the diffraction gratings 7 and 9 Consequently, even when both diffraction gratings 7 and 9 are arranged closely to each other, their diffracted beams can be detected separately and independently with ease