| 摘要 |
PROBLEM TO BE SOLVED: To precisely control the distance between an objective lens and an object. SOLUTION: This controller 20 is constituted so that light beams 2 are radiated onto the object 4 through the objective lens 3, the focus state of the objective lens 3 is detected as movement of position of a reflection luminous flux 5 from the object 4 by a photodetector 21 and the focus state of the objective lens 3 is adjusted based on a detection signal 22 in the photodetector 21. In such a case, the photodetector 21 is constituted of a photoreceiving body group consisting of plural photoreceiving bodies P1, P2,... PN-1, PN of the same size subdivided in the direction X that the position of the reflection luminous flux 5 is moved, and the position of the photoreceiving body PN light-receiving the maximum light quantity among the photoreceiving bodies P1, P2,... PN-1, PN of the photodetector 21, or the position that the position of the photodetecting body PN light receiving the maximum light quantity is correction operated according to the light receiving amounts of front/rear photoreceiving bodies to be obtained is detected as the position of the reflection luminous flux 5. This exposure device is provided with the controller 20.
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