| 摘要 |
PROBLEM TO BE SOLVED: To eliminate trouble in a laser drive controller, e.g. breakdown due to dew formation. SOLUTION: A dew formation sensor and a temperature sensor for a laser diode LD are provided and operated as follows under control of a control section. When start of exposure is designated, the LD is checked for dew formation (S10). If dew formation is present in the LD, temperature of the LD is checked against a specified level (S14, 816) and error processing is performed (S26) because the operating environment is inappropriate if the specified level is exceeded otherwise an offset current lower than a threshold level is fed (S18). Consequently, dew formation is eliminated by raising the temperature of the LD and then exposure is started by driving the LD (S22). If dew formation is not eliminated within a specified time after starting offset current supply, exposure is not started but error processing is performed (S24, S26).
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