METHOD AND DEVICE FOR EVALUATING PRISM UNIT AND METHOD OF MANUFACTURING PRISM UNIT

摘要

A method for evaluating a prism unit (20A) having a plural number of prisms (22, 23) with an air gap between air gap surfaces (b, c) tilting against an optical axis. A performance of the prism unit is evaluated based on an astigmatic difference which is a difference between an image point in a first direction X which is orthogonal to a plane (YZ plane) formed by an optical axis and normal lines of the air gap surfaces (b, c) crossing the optical axis and an image point in a second direction which is orthogonal to the first direction X and the optical axis. The performance evaluation may be carried out with regard to one of three primary colors and may be carried out with regard to every of three primary colors.