| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a surface position detector in which a long optical path is not required even in the case of oblique incidence where the angle of incidence is large, and a prism used for bending a light beam can be arranged without separating excessively from a detected surface in the height direction.SOLUTION: In a surface position detector including a projection optical system, a reception optical system and a photoelectric conversion element, and detecting positional deviation of the detected surface from a reference surface, at least one of the projection optical system and reception optical system has a reflection member. The reflection member includes a first reflection face arranged closest to a detected region, and a second reflection face arranged farthest from the detected region. When an axis extending in the normal direction of the reference surface is a first axis, a first extension surface extending the first reflection face to the reference surface side crosses the first axis at a first angle. The angle formed by the detection light progressing on the second reflection face on the side opposite to the first reflection face and the detection light is smaller than the angle formed by the detection light progressing between the detected region and the first reflection face and the first axis.</p> |
