LASER INTERFEROMETRIC DIFFRACTOMETRY FOR MEASUREMENTS OF DIFFRACTION GRATING SPACING

Two methods and an experimental setup for the measurement of spacing o f diffraction gratings have been developed. These methods depend on in terferometric measurements at different wavelengths of the angles of d iffraction beams from the grating to be measured. A lower limit for th e measured spacing is the half-wavelength of laser radiation. The resu lts of spacing measurements of approximately 0.28, 0.39, and 0.50 mu m are presented. (C) 1996 Optical Society of America