| 摘要 |
An apparatus for controlling the exposure for successively exposing or printing the same pattern in the different areas on a photosensitive surface of a photosensitive substrate such as a wafer or a photographic mask. The intensity of the light projected onto the photosensitive surface from a light source through a shutter is detected in response to the full opening of the shutter. The required exposure time is computed in accordance with the detection result and a desired exposure and the closing operation of the shutter is started when there is a special relation between the measured shutter time count and the computed result. To prevent any waste of the light source, the light source performs its light emitting operation such that alternate relatively high-intensity emission and relatively low-intensity emission are periodically repeated and the average input power to the light source during the interval is maintained at a predetermined value.
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