| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical element in which an optical length is ensured despite its compact design and manufacturing accuracy is improved without increasing its cost. SOLUTION: The optical element OE includes a transparent body which has two refracting faces R1 and R5 and a plurality of reflecting faces R2 to R4 and in which, when the optical element OE is disposed in an optical system, a central principal ray PR from the center of the face of an object to the center of a pupil via each face crosses itself within the transparent body. In the optical element OE, projecting parts HP having no optical actions are disposed on both sides of the transparent body. When one and the other areas having, as their boundary, a first flat plane PP passing through both the projecting parts are defined as a first area I and a second area II, the plurality of reflecting faces are arranged in the first area and the second area alternately in order in which the central principal ray propagates. COPYRIGHT: (C)2006,JPO&NCIPI
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