| 摘要 |
A reflection optical system placed between a light valve 5 and a screen 4, wherein curved surfaces are only three reflection surfaces of first to third mirrors 1 to 3, and satisfies the following: (1) thetaL<20 degrees, (2) 25 degrees<thetaUL<55 degrees, (3) 20 degrees<thetaM1<55 degrees, (4) 15 degrees<thetaM2<50 degrees, (5) 8 degrees<thetaM3<30 degrees, (6) thetaL<15 degrees, (7) 30 degrees<thetaUL and (8) 7.5 degrees<|thetaF|, where thetaL: minimum angle which a light beam of pupil center forms with respect to the enlargement side image surface; thetaUL: difference between maximum and minimum angles which a light beam of pupil center forms with respect to the enlargement side image surface; thetaM1, thetaM2 and thetaM3: deviation angles of the light beam of pupil center passing the center of the reduction-side image surface in first to third mirrors 1 to 3; and thetaF: reduction-side pupil divergent angle.
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