臨界角法のワイドレンジにおける平滑効果の考察

Abstract

An optical skid that uses the wide range of the critical angle method has a smoothing effect on high spatial frequency components. In the present paper, the extent of smoothing is estimated on grooves and gratings by calculating the intensity distribution on a detection photodiode taking into account the spherical aberration of the objective lens. Computer simulation shows that the spherical aberration of the lens at the image plane where the photodiode has been placed is the main factor responsible for the smoothing effect, the smoothing effect increases as the aberration increases. It is also shown that the ray which has twice reflections on the surface profile is another cause of the smoothing effect. Furthermore, with respect to grooves, the characteristics of the smoothing effect are seen to be related to the width and depth of the grooves, they increase as the depth increases or the width decreases. Good agreement is observed between the simulation results and the experimental results.