Optical system phase acquisition method and optical system evaluation method

Abstract

When the optical system is illuminated with an illumination light flux emitted from one extant input image point, an interference image generated by superimposing an extant output light flux output from the optical system and a reference light flux coherent with the extant output light flux is imaged to acquire interference image data, and thus to acquire measured phase distribution, and this acquisition operation is applied to each extant input image point. Thus, each measured phase distribution is expanded by expanding functions μn(u, v) having coordinates (u, v) on a phase defining plane as a variable to be represented as a sum with coefficients Σn{Ajn·μn(u, v)}. When the optical system is illuminated with a virtual illumination light flux, a phase Ψ(u, v) of a virtual output light flux is determined by performing interpolation calculation based on coordinates of a virtual light emitting point.