| 摘要 |
PURPOSE:To surely detect a magneto-optical signal by a constitution in which the number of parts is small, by placing a prescribed wavelength plate and a half mirror in a feedback optical path. CONSTITUTION:A linearly polarized light which has been rotated by a prescribed angle by a magneto-optical disk 19 is increased as to its virtual rotational angle in accordance with setting of a reflection factor and transmittivity of a beam splitter 17, passes through a lambda/4 plate 22 and becomes an elliptic polarization, transmits through a half mirror 23 and reaches a servo-detecting system 21. On the other hand, a reflected light of the mirror 23 passes through the plate 22 again and becomes a linearly polarized light. When a transmission light of the plate 22 passes through the splitter 17, the splitter 17 functions as an analyzer. This light is detected by a photodetector 24, and a magneto- optical signal is obtained.
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