Patent ID: 7001031
Filing Date: 2006-02-21
Classification: G02B,H04N

Abstract:
1. An image forming optical system provided with a plurality of curved mirrors whereby a first conjugate point and a second conjugate point are made to have an optically conjugate relationship, when an optical path is traced from said first conjugate point to said second conjugate point, in order starting with said first conjugate point, comprising: a first mirror with an optical power which reflects luminous flux from said first conjugate point to transform the luminous flux into substantially parallel luminous flux; a second mirror with an optical power which reflects the luminous flux reflected by said first mirror while keeping said luminous flux substantially parallel; a third mirror with an optical power which reflects the luminous flux from said second mirror; a fourth mirror with an optical power which reflects the luminous flux from said third mirror; a fifth mirror with an optical power which reflects the luminous flux from said fourth mirror; and a sixth mirror with an optical power which reflects the luminous flux from said fifth mirror, wherein the following condition is satisfied: where ξ is an absolute value of an angle formed by the normal of said first mirror and a reference axis at an intersection of said reference axis and said first mirror, said reference axis is an optical path along which a central ray of the luminous flux from said first conjugate point progresses, η is an absolute value of an angle formed by the normal of said second mirror and said reference axis at an intersection of said reference axis and said second mirror, and F is an effective F number on said first conjugate point side, and wherein a third conjugate point having an optically conjugate relationship with said first and second conjugate points is formed between an optical path of said fifth mirror and said sixth mirror.