| 摘要 |
PURPOSE:To raise the accuracy of focus setting by providing the second reflector for reflecting further one of optical beams reflected by the first semi-transmitting mirror, in the direction of the first semi-transmitting mirror, and an optical means for observing each light reflected by the same surface of the first semi-transmitting mirror. CONSTITUTION:A slit 11 and a lens 12 constitute a part of a beam shaping optical system. The first recording beam 14 is rectangular. A polarized beam splitter 13 adds the first recording beam 14 and the second recording beam shown in a figure 15. Light which has passed through the polarized beam splitter 13 or has been reflected is led to a wedge plate 16, respectively, reflected by each end face, reflected partially by a semi-transmitting mirror 17, and led to a collimating system 26. On the other hand, light which has passed through the semi-transmitting mirror 17 is focused by a lens 18, and converted photoelectrically by a photoelectric converting element 19. The recording beam which has passed through the wedge plate 16 is totally reflected by a total reflection mirror 27, led to a recording lens 24, and focused onto a recording medium 25.
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