Patent ID: 8199231
Filing Date: 2012-06-12
Classification: G02B

Abstract:
1. An image pickup element unit comprising: a substrate; an image pickup element arranged on said substrate and configured to pick up an object image and output an electric signal corresponding to the object image; and an optical low-pass filter disposed between a photographic lens and said image pickup element, said optical low-pass filter including a phase grating having unit cells disposed in a regular pattern at a grating pitch P, said unit cells being formed by equal-width recesses and equal-width protrusions adjacent to each other; a spacer disposed between said image pickup element and said optical low-pass filter and configured to keep a predetermined spacing D therebetween; and a cover glass arranged to hermetically seal said image pickup element and said optical low-pass filter in association with said substrate, wherein when a shortest wavelength of light employed is λS, and a longest wavelength of light employed is λL, an optical path difference ΔH between lengths of optical paths of the shortest wavelength of light and the longest wavelength of light of which a phase is varied by said phase grating, is larger than λS/2, and at the same time smaller than λL/2, and wherein said optical low-pass filter and said image pickup element are arranged such that the predetermined spacing D between said phase grating and said image pickup element satisfies the relationship P