Patent ID: 6943888
Filing Date: 2005-09-13
Classification: G02B,G03F

Abstract:
1. A pattern reading apparatus, comprising: a minute-area light source that causes an illumination light beam to be incident on an object surface having a pattern formed thereon as an object to be read; an objective lens that converges a light beam carrying the information of the pattern; a spatial filter having a shading region that shades a portion of the light beam that forms an image of said light source from the light beam, said spatial filter shielding non-diffusing component of the light beam and permitting formation of an image by the diffusing component of the light beam, said spatial filter being positioned such that a size of an image of said light source formed by said objective lens is smaller than a size of the image at a paraxial image point; and an imaging lens that forms the image of the pattern using the portion of the light beam that passes through said spatial filter.