| 摘要 |
PURPOSE:To improve C/N in terms of signal detection by using a polarization beam splitter with an optimum polarization characteristic for a magneto-optical information reproducing device and setting the optical axial orientation of a detection means most suitable. CONSTITUTION:A semiconductor laser 21 emits a P polarization luminous flux, and projects a light spot with an intensity I0 to a recording medium 26 through the polarization beam splitter 12. The reflected luminous is modulated to be polarized, and led to a photodetector 27. Here the mean of the intensity of a polarization component which is not subjected to modulation due to an magnetic optical effect is denoted as IR, the mean of the squared fluctuation of intensity in a magneto-optical signal observation frequency as DELTAI<2>, xsi is shown by equiation 1, the luminous energy of light incident on the recording medium 26, is denoted as I0, amplitude reflectance as R, light usage efficiency from the recording medium to a photodetector 29 except for the splitter 12 and a light detection means as epsilon, amplitude transmissivity as tA, a quenching rate as etaA, photoelectric conversion efficiency as (kappa), the thermal noise of an amplification means as T, the band width of a detection signal as DELTAB, amplitude reflectance with respect to the polarization component in the prescribed direction of the splitter 12 as rP, amplitude reflectance with respect to the polarization components in the prescribed and vertical directions and an angle made by the optical axis of the light detection means and the prescribed direction as thetaA. All of them satisfy equations II-IV.
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