MEASUREMENT EQUIPMENT FOR DECENTRATION OF ASPHERICAL LENS

摘要

PROBLEM TO BE SOLVED: To improve precision of decentration measurement by allowing an incidence optical system to include at least one optical element wherein astigmatic difference can be variably generated, or the astigmatic difference amount can be variably compensated, so that observed reflection spot diameter is suppressed to sufficiently small one. ;SOLUTION: The incidence optical system which makes light flux incident on a sample lens surface 11 comprises a light source 101 movable in the light axis direction, a beam splitter 5 which divides the light from the visible semiconductor laser light source 101, a projection lens 3, a mirror 111 movable in the direction of arrow x1. Further the incidence optical system in provided with an optical element 1 wherein, assigned between the light source 101 and the beam splitter 5, astigmatic difference can be variably generated. With the function of the element 1, appropriate astigmatic difference is supplied to incident light flux so that the astigmatic difference disappear in the light flux reflected on the sample lens surface 11.;COPYRIGHT: (C)1997,JPO