LENS SHAPE DESIGN METHOD, IMAGING ELEMENT, AND PHOTOMASK DESIGN METHOD

摘要

PROBLEM TO BE SOLVED: To provide a lens shape design method for minimizing the loss of incident light to a light receiving element of an imaging element used for an imaging device, which is suitably used when a layer below a lens is formed of a plurality of layers differed in refractive index.

SOLUTION: The method comprises: determining an optical path of refracted light into a lens material by performing calculation of tracking light beam reversely to an actual advancing direction of light beam within a laminated material in a setting in which the light beam is emitted at a fixed angle to an optical axis with a target position of light collection as a starting point; determining an intersection of the determined optical path of refracted light with the optical axis by extending the determined optical path; designing a rotary elliptic lens such that it has a focal point in the position of an apparent focal point while taking this intersection as the apparent focal point, on the assumption that the laminated material is the same material as the lens material; and taking a part of the surface shape on the parallel incident light beam group side of the designed rotary elliptic lens as a lens shape to be obtained.

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