| 摘要 |
PROBLEM TO BE SOLVED: To perform a control of a high-accuracy exposure at the best throughput to an exposure error by a method wherein an exposure correction width is found by the time when an exposure is completed and the mean output energy of a laser and the number of exposure pulses are decided on the basis of this width and a necessary exposure to perform the control of the exposure. SOLUTION: The output of a photosensor 6 is converted into an exposure in every one pulse of a laser via a sensor amplifier 7. A CPU 8 operates the following output value of the laser on the basis of the exposure measured in the photosensor 6 and gives an output energy command value to a laser light source 1. Then, an exposure correction width (α) necessary for correcting an exposure error, which depends on the rotation of an illuminance unevenness eliminator, is found. This width (α) is stored by a method wherein the relation between the factor of an exposure error, for example, and the mean output energy of the laser is previously measured and the value of 1/2 of the fluctuation width of the exposure error is kept stored one of exposure parameters. Then, the total number of exposure pulses to satisfy a set exposure and the mean output energy of the laser are decided on the basis of this width (α).
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