| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a space saving projection optical system without astigmatism in the case of a non-telecentric optical system successively synthesizing three beams with a mirror system. SOLUTION: Dichroic mirrors 4, 5 are arranged at the same tilt angleθon the position so that a surface S1 containing an incident optical path B1 and a reflection optical path (transmission optical path of green beam) G1 of a blue beam reflected by the reflection surface 5a of the dichroic mirror 5 is orthogonally intersected with the surface S2 containing the incident optical path R1 and the reflection optical path G1 of a red beam reflected by the dichronic mirror 4. Together with that, the dichroic mirrors 4 is constituted of joining two sheets of glass substrates 4a, 4b, and the reflection layer 4c of the red beam is formed on its joint surface.</p> |
