Profilometry gives good possibility to evaluate a quality of diffractive optics. However, distorted representation of diffractive zone boundaries inherent to majority of profilometric devices does not allow correct restoring the diffraction efficiency on the base of the profilogram. Similar problem appears at numerical optimization of direct laser writing or grey-tone lithography process for diffractive optics fabrication, because typical merit function for the optimization is the diffraction efficiency. The paper describes unified approach to characterization of continuous-relief DOEs and to optimization of fabrication process for these elements. Generalized point-spread function of the fabrication process (GPSF) has been used to simulate a grating profile for optimization of fabrication process and for evaluating the diffraction efficiency from profilometric data. For optimization purpose a designed profile is convoluted with GPSF for simplified modeling profile forming. For characterization purpose the diffractive structure is simulated by convolution of GPSF and a function approximating the profile measured by a profilometer. The results of numerical optimization and profilometric characterization for DOEs fabricated by graytone lithography have been considered.

Date Published: 14 May 2010
PDF: 9 pages
Proc. SPIE 7718, Optical Micro- and Nanometrology III, 77180S (14 May 2010); doi: 10.1117/12.854416

Published in SPIE Proceedings Vol. 7718:
Optical Micro- and Nanometrology III
Christophe Gorecki; Anand Krishna Asundi; Wolfgang Osten, Editor(s)