| 摘要 |
PURPOSE:To reduce the number of parts, to simplify constitution and to easily miniaturize a device by providing a system detecting light read out of a photomagnetic recording medium with a birefringence plate and obtaining a differential output. CONSTITUTION:The birefringence plate 40 is arranged by tilting 45 deg. with respect to the incident angle of light from the photomagnetic recording medium, and light receiving elements 42 and 44 independently detect an S polarization component and a P polarization component, both of which the plate 40 splits. The outputs detected by the elements 42 and 44 are inputted to a differential amplifier 46 to detect a differential output, and digital information is read out. Thus, such a complicated constitution is unnecessary that a half prism and a photodetector are combined, and only one birefringence plate 40 can obtain a differential output. Therefore the number of parts is reduced to simplify the constitution, and the device can be easily miniaturized.
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