| 摘要 |
PROBLEM TO BE SOLVED: To provide a measuring device capable of preventing device down (elongating a lifetime) applied to the exposure device, and warning early throughput decline and optical system unit deterioration. SOLUTION: This device has a light source 12; two accumulation type photodetectors 9, 10; a dimmer 11 which is used in common for the two photodetectors, for adjusting a light quantity from the light source; and a controller 13 for controlling the dimmer so that each output from the two photodetectors falls within a tolerance. The device performs measurement by detecting respectively two lights from an object illuminated by light whose light quantity is adjusted by the dimmer by the two photodetectors. In this case, when only either output from the two photodetectors falls within the tolerance by control by the dimmer, the controller sets the other accumulation time so that the other output from the two photodetectors falls within the tolerance. COPYRIGHT: (C)2008,JPO&INPIT
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