| 摘要 |
The present invention solves the problem that, in an observation device such as an ellipsometer, aberration in an image formed by an equal-magnification reflection type image forming optical system becomes large. An ellipsometer 100 is provided with an image forming optical system 30 for imaging, on a light receiving surface 40, luminous flux of reflection light from an object surface S. The image forming optical system 30 includes a concave main mirror 32, a convex auxiliary mirror 34, and a drawing plane mirror 36. The image forming optical system 30 is formed of an equal-magnification reflection type image forming optical system which can cause luminous flux of reflection light from the object surface S to be reflected by the concave main mirror 32, the convex auxiliary mirror 34, and the concave main mirror 32, in this order, and then, image the luminous flux on the light receiving surface 40 via the drawing plane mirror 36. The convex auxiliary mirror 34 is a rear surface mirror. |
