| 摘要 |
PURPOSE:To prevent accuracy unstableness and an accuracy decrease from being caused by taking a measurement while slanting the measurement surface of an object of measurement to a parallel scanning light beam so that when the parallel scanning light beam scans on the object of measurement, its reflected light is not incident on a photodetector for the temperature compensation of a semiconductor laser light source. CONSTITUTION:An optical axis 62 of measurement which connects a polygon 16, a collimator lens 18, a condenser lens 22, and the photodetector 26 is slanted previously to the center axis of a measuring instrument 60 so that the object 24 of measurement can be set slantingly to the optical axis. Consequently, the light reflected by the surface of the object 24 of measurement never returns to a semiconductor laser unit through the collimator lens 18 and polygon 16. Therefore, a laser output is prevented from varying owing to the reflected light and a measurement is taken stably.
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