| 摘要 |
<P>PROBLEM TO BE SOLVED: To aim at miniaturization of the device by reducing the number of members and to aim at improving the performance. <P>SOLUTION: Three light receiving surfaces of a photo detector 21 are composed of a main beam light receiving surface 22 for receiving a 0-order light and a pair of sub-beam light receiving surfaces 23 and 24 for receiving ±1st light respectively which are located opposite to each other with the main beam light receiving surface 22 in between. The main beam light receiving surface is quatered by two cross-shaped area dividing lines 22a and 22b. On each of the pair of sub-beam light receiving surfaces, the first spot dividing lines 23a and 24a and the second spot dividing lines 23b and 24b for dividing each of light receiving spots of a laser beam having the first wavelength and a laser beam having the second wavelength in the direction in which the three light receiving surfaces are arranged are formed. <P>COPYRIGHT: (C)2004,JPO |
