| 摘要 |
PURPOSE:To detect the accurate temperature of even a wafer being heated by photoirradiation at all times by cooling the aperture stop of the objective in a light measurement optical system. CONSTITUTION:The temperature measurement optical system 10 provided below the center of a quartz chamber 2 consists of the objective 7 which forms an image of the wafer 5 through the aperture stop SA, the relay lens composed of two positive lens groups 8 and 9 for re-forming the wafer image obtained by the objective 7 on a detector 11, and a mirror 12 for two-dimensional scanning and a filter 13 which are arranged at a position S1 conjugate to the aperture stop. Then a cooling means 20 is provided at the periphery of the aperture stop SA and cooling water is supplied at all times by a circulation system to hold the aperture stop SA below constant temperature. Thus, the aperture stop SA of the objective is cooled to minimize heating emitted light incident directly on the temperature measurement optical system from a heating device and heating emitted light from a body to be heated by the aperture stop SA of the objective 7.
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