OPTICAL DIMENSION MEASURING METHOD AND DEVICE

摘要

PROBLEM TO BE SOLVED: To suppress the sudden change of a measurement value by a temperature change. SOLUTION: In the measurement of the dimension or displacement of a measuring object by use of a laser beam 10 oscillated by a semiconductor laser 20 of single mode with concentrated oscillation spectrum, the working current of the semiconductor laser 20 is subjected to high frequency modulation and made into a multi mode to minimize the influence by mode hop.