実用的なスポット像からの波面収差解析手法の開発(機械力学,計測,自動制御)

抄録

Aberration retrieval is an important technology for evaluation of quality of imaging optics. In this study, a practical system that identifies the aberration of imaging optics from spot intensity images has been developed. The complex amplitude distribution of spot on defocus plane is expanded to Nijboer-Zernike series and neglect higher order terms. Then the identification problem is reduced to the non-linear optimization problem whose design variables are Nijboer-Zernike coefficients. This problem is solved by the quasi Newton method. In addition, some accuracy improvement techniques have been applied to this method. These techniques are summarized as follows. (1) The captured spot intensity images are filtered with low-pass filter whose cutoff frequency is decided from the numerical aperture of imaging optics. (2) The background level is taking account for numerical model of intensity image, and background level is also identified during the optimization process. Some numerical experiments and practical ones were performed to demonstrate the effectiveness of the present method. In addition, four kinds of practical experiment based on theories were performed, and all of these experiment got high correlation between input parameter and measurement result and high consistency with theoretical forecast. These results proved that this aberration retrieval method have enough capability to be used practically.