Patent ID: 6278554
Filing Date: 2001-08-21
Classification: G02B

Abstract:
An image pickup optical system comprising:an optical element of a transparent, optical material comprising an entrance surface, at least one reflective surface, and an exit surface, said optical element having an optical power; andan image pickup element comprising a plurality of pixels, wherein on the image pickup element an image is formed by light from an object through said optical element,wherein said optical material is a material having an index change amount .DELTA.n from an absolute dry condition at the temperature of 50.degree. C. to saturation under a circumstance of the temperature being 50.degree. C. and the humidity being 90%, the index change amount .DELTA.n satisfying the following condition:.DELTA.n.ltoreq.F.delta.r.sub.0.sup.2 /(2f.sup.2 L)where F is the F-number of said image pickup optical system, f is the focal length of said image pickup optical system, .delta. is the pitch of the pixels of said image pickup element, L is the optical path length of said optical element along the reference axis, and r.sub.0 is half of the length of said optical element along a direction perpendicular to a plane including the reference axis.