Patent ID: 8223419
Filing Date: 2012-07-17
Classification: G02B,H04N

Abstract:
1. A scanning optical system comprising: a light source for emitting a light flux with a wavelength of 500 nm or less, a deflecting optical system for deflecting the light flux emitted from the light source to carry out a scan in a main-scanning direction; and a scanning and image-forming optical system for forming a light flux deflected by the deflecting optical system into an image on a scanning surface, wherein the scanning and image-forming optical system comprises a first plastic lens arranged to be adjacent to the deflection optical system, the scanning optical system satisfies 0.05≦NA where NA wherein the first plastic lens is a plastic lens comprising a resin comprising a copolymer of α-olefin and cyclic olefin, as a base material, and the cyclic olefin is represented by the following general formula (I) or (II): where, in the general formula (I), n is 0 or 1, m is 0 or a positive integer, k is 0 or 1, and each of R where, in the general formula (II), each of p and q is 0 or a positive integer independently, each of r and s is one of 0, 1, and 2 independently, each of R