ASPHERICAL OPTICAL ELEMENT, IMAGE READER, AND METHOD FOR MANUFACTURING ASPHERICAL OPTICAL ELEMENT

摘要

PROBLEM TO BE SOLVED: To provide an aspherical optical element capable of highly accurately measuring the position of an optical effective surface having a non-rotationally symmetrical aspherical shape, in a rotational direction, with a simple configuration.SOLUTION: An aspherical optical element 100 includes an optical effective surface 101 formed of a non-rotationally symmetrical aspherical surface and a plurality of projecting parts or a plurality of recessed parts 102 and 103 provided in the front surface of the optical effective surface 101. In the optical effective surface 101, other parts except a part in which the plurality of projecting parts or the plurality of recessed parts 102 and 103 are provided are shaped to be continuous.