| 摘要 |
PURPOSE:To improve the incident/outgoing efficiency between a light waveguide and a space by providing blaze effect to a bent type diffraction grating of the optical waveguide so as to suppress the production of high-order diffraction wave. CONSTITUTION:The light from a semiconductor laser 21 is led to an optical waveguide layer 19 by the end face coupling and a minute spot is formed on a disk 23 by a coupling lens 22 and an objective lens 20. The light reflected from the disk passes through the objective lens 20, reflected in the polarized beam splitter 25 and made incident in a linear arrangement four-split photodetector 27 by a condenser lens 26. The blade type is adopted for the cross sectional shape of the objective lens 20 being the diffraction grating (on condition that the slope and the direction of light wave propagation are made perpendicular) and the production of high-order diffracted light is prevent more than the binary type, when the efficiency is improved. |
