In order to fabricate orthogonal crossed gratings, we propose an interference fringe based alignment technique to adjust the angle between the two Lloyd’s mirrors to be 90° in the dual Lloyd’s mirror interferometer. An exposed crossed grating is put back to the exposure system and rotated about 90° around its normal direction. By observing the fringe spacing of the interference fringes generated by the diffracted beams of different orders, we can adjust the angle between the two Lloyd’s mirrors to be 90°. Simulation results indicate an orthogonality error smaller than 4″ can be obtained by this method. We fabricated a crossed grating with 0.30″ orthogonality error.

Date Published: 19 October 2016
PDF: 8 pages
Proc. SPIE 10155, Optical Measurement Technology and Instrumentation, 101553Q (19 October 2016); doi: 10.1117/12.2247443

Published in SPIE Proceedings Vol. 10155:
Optical Measurement Technology and Instrumentation
Sen Han; JiuBin Tan, Editor(s)