| 摘要 |
<P>PROBLEM TO BE SOLVED: To make light transmittance increasable without causing the loss of light quantity and the increase of wave aberration. <P>SOLUTION: In the diffraction grating for a plurality of wavelength 10, the cross section is formed in a periodically rugged pattern, and a 1st grating area 11 is formed long and slender in a depth direction orthogonal to the repeating direction of the rugged pattern, and a 2nd grating area 12 has the same constitution and has a recessed part whose groove depth is set different from the groove depth of the recessed part of the 1st grating area 11, and by alternatively arranging the 1st grating area 11 and the 2nd grating area 12, a stripe pattern is formed, and the groove depth of each recessed part of both grating areas 11 and 12 is set so that incident light of 1st wavelength is transmitted through the 1st grating area 11, and incident light of 2nd wavelength different from the 1st wavelength is diffracted in the 1st grating area 11, and also, the incident light of the 2nd wavelength is transmitted through the 2nd grating area 12 and the incident light of the 1st wavelength is diffracted in the 2nd grating area 12. Besides, such the diffraction grating 10 is used for an optical pickup device and an optical disk device. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
