| 摘要 |
In a magneto-optical information reproducing apparatus comprising means for applying a light beam polarized in a predetermined direction onto a recording medium on which information is magnetically recorded, means for dividing the reflected or transmitted light beam from the recording medium modulated into a polarized state in conformity with the information by the magneto-optical effect, a plurality of analyzer means having their optic axes inclined in opposite directions with respect to the predetermined direction and analyzing the divided light beams, a plurality of photodetectors having no amplifying action and photoelectrically detecting the light beams transmitted through the plurality of analyzer means, and a signal processing circuit for amplifying the detection signals of the plurality of photodetectors, differentiating them and reproducing the information, the angle theta A formed between the optic axes of the plurality of analyzer means and the predetermined direction satisfies the following conditions: <IMAGE> S = 2e kappa epsilon ¦tA¦2¦R¦2I0 x DELTA B where I0 is the quantity of light of the incident light beam on the recording medium, R is the amplitude reflectance of the recording medium, epsilon is the light utilization efficiency of the optical system from the recording medium to the photodetectors except the analyzer means, kappa is the photoelectric conversion efficiency of the photodetectors, e is the amount of charge, T is the thermal noise of the amplifying means in a magneto-optical signal observation frequency, DELTA B is the band width of the detection signals, tA is the amplitude transmittance of the analyzer means, and eta A is the extinction ratio of the analyzer means.
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