| 摘要 |
A surface position detection device detects the position of a surface to be detected with an uneven profile. The device includes an illumination unit, first and second imaging optical systems, a photodetector, and a position detector. The first imaging optical system projects the image of the object onto a surface to be detected. The second imaging optical system re-focuses the image of the object reflected from the surface to be detected. The photodetector detects the image re-focused by the second imaging optical system. The position detector detects the position of the surface to be detected, based on the signal generated by the photodetector. The first imaging optical system comprises a first aperture member defining the cone angle of a light ray flux projected onto the object, which is denoted as phi TRANSMIT. The second imaging optical system comprises a second aperture member for defining the cone angle of the light ray flux, reflected from the surface to be detected, and detected by the photodetector, which is denoted as phi RECEIVE. phi TRANSMIT>/= phi RECEIVE.
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