INPUT AND OUTPUT DEVICE FOR OPTICAL INFORMATION

摘要

PURPOSE:To simplify the consitution of an input/output device for optical information by setting a variable focus lens at a position closer to a light source than a light isolator and therefore omitting a special element which is needed to set the bearings of the linear polarization in the same direction. CONSTITUTION:The linear polarized laser light radiated from a laser light source 1 is transmitted through a variable focus lens 8 and a polarized beam splitter 3 and converted into the circular polarized light by a 1/4 wavelength plate 9. This circular polarized light is condensed on the recording surface of an information recording medium via an objective lens 10. The light reflected by the medium 6 travels back the above-mentioned route and is converted into the linear polarized light by the plate 9. In this linear polarized light, an electric vector is turned by 90 deg. to the linear polarized light of the going route and its direction is therefore bent by the splitter 3 and the light is received by a photodetector 7.