| 摘要 |
PROBLEM TO BE SOLVED: To obtain an apparatus and a method for detecting laser beam characteristic change whereby the spread of the beam shape due to making a high power structure, the right-left asymmetry, the degree change, etc., can be easily and exactly detected. SOLUTION: A photodetecting means 30 has a photodetecting surface divided for a photodetector element A disposed on the optical axis of a semiconductor laser 20 and a right and left photodetector elements B1, B2 adjacent to it. An inspection part 50 evaluates the total light characteristic from the sum of the output Ia of the photodetector element A and the outputs Ib1 and Ib2 of the photodetector elements B1, B2 and detects the nonlinearity of the right- left spread of the beam shape from a nonlinearity of the change characteristic to the exciting intensity (Ib1+Ib2)/Ia, and the total light characteristics and the right-left asymmetry of the beam spread are all measured during one scan of the exciting intensity.
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