MAGNETO-OPTICAL REPRODUCING DEVICE
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专利名称：MAGNETO-OPTICAL REPRODUCING DEVICE 发明人：SEKIGUCHI TORU,SASAKI YOSHIHIRO
申请号：JP15809287
申请日：19870624
公开号：JPS643841A
公开日：
19890109
专利内容由知识产权出版社提供
摘要：PURPOSE:To make the whole signal incident on the effective photodetection surface of a photodetector and to improve the SN ratio of signal detection by selecting the numerical aperture of a condenser lens so that the diameter of the signal light is smaller than the effective photodetection diameter of the photodetector. CONSTITUTION:Condenser lenses 10A and 10B are so designed that an expression I holds for the numerical aperture NA, where lambda is the wavelength of laser light, (w) the diameter of the effective photodetection surfaces of photodetectors 11A and 11B, and (k) a constant nearly equal to 1. Consequently, the whole signal light is incident on the effective photodetection surfaces of the photodetectors 11A and 11B and playback signal light is converted into an electric signal without any waste, thereby reproducing the signal from a magneto-optical recording medium 6 with an excellent SN ratio.
申请人：NEC CORP
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