In fabricating a diffractive optical element the ratio of the etching depth between the (<i>n</i> − 1)th and the <i>n</i>th mask is usually 1/2. We found that the diffraction efficiency of a diffractive optical element can be improved by as much as 7.8% if the above ratio (1/2) is not kept constant. For achieving this improvement the difference between the desired and the actual diffraction pattern is also used as an objective function for phase quantization.
© 2001 Optical Society of America
Chung J. Kuo, Hung C. Chien, Ni Y. Chang, and Chia H. Yeh, "Diffractive Optical Element Designed by Use of an Irregular Etching-Depth Sequence," Appl. Opt. 40, 5894-5897 (2001)