| 摘要 |
PROBLEM TO BE SOLVED: To provide a projection optical system capable of achieving the miniaturization and thinning of a device though an aspherical mirror is used. SOLUTION: The projection optical system has: a first optical system possessing a first (a) group having positive power and a first b group having negative power, and having positive power as a whole; a second optical system possessing a reflection surface having negative power; and a first deflecting means for guiding the luminous flux emitted from the first optical system to the second optical system in order from a display element side. The first deflecting means is positioned above the first optical system on a cross section including a line passing through the center of the screen of the projection device in an ordinary using state and extending in a vertical direction, deflects the incident luminous flux in a direction where the luminous flux goes away from the screen and guides it to the second optical system. The projection optical system satisfies following respective conditions: 6.0>D/f1>2.6 and -1>EXP1/f1>-2.2. Here D is a distance from the final surface of the first optical system to the second optical system, f1 is the focal distance of the first optical system, EXP 1 is a distance from the final surface of the first optical system to an exit pupil, respectively. COPYRIGHT: (C)2008,JPO&INPIT
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