| 摘要 |
PURPOSE:To simultaneously measure an angle of torsion, transmittivity, and a reflection factor by a measuring light of an arbitrary wavelength safely and in a short time by one device, by photodetecting transmission light and reflected light by a beam splitter to be measured, by position detecting detectors, respectively. CONSTITUTION:A divergent light from a light source 11 of a semiconductor laser, etc. is made incident as a parallel luminous flux onto a beam splitter to be measured 13 by a collimator lens 12. Its transmission light is photodetected by a position detecting detector 15a through a condensing lens 14a, and also, its reflected is photodetected by a position detecting detector 15b through a condensing lens 14b in the same way. The position detecting detector 15a is constituted of a photodetector having 4-split photodetecting areas 16a-16d, and the sum of outputs of the photodetecting areas 16a, 16b arranged in the (y) direction, and the sum of outputs of the photodetecting areas 16a, 16d are derived by adders 17a, 17b respectively. By subtracting the outputs of these adders 17a, 17b by a subtracter 18a, position information in the (x) direction of a spot 19 condensed onto the detector 15a is obtained.
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