| 摘要 |
PROBLEM TO BE SOLVED: To reduce losses to be generated when light is received with a diffraction grating, without making the diffraction grating larger. SOLUTION: An optical diffraction apparatus is provided with an optical fiber 2 for emitting an elliptic beam, and a diffraction grating 4 which is provided with diffracting grooves in a direction vertical to the major axis of the elliptic beam and diffracts the elliptic beam. Since the length in the direction of the minor axis 10S of a beam spot 10 is short, the diffraction grating 4 can be reduced in size moreover in the direction of the minor axis 10S, compared with the case where the beam spot 10 is circular. Moreover, the spectral resolution of the diffraction grating 4 is proportional to the number of diffracting grooves 4a on the beam spot 10. Here, the number of the diffracting grooves 4a on the beam spot 10 can be increased, since the diffracting grooves 4a are vertical to the major axis 10L of the beam spot 10. Accordingly, it is not necessary to reduce the spectral resolution of the diffraction grating 4 so much, in spite of having made the beam spot 10 smaller. COPYRIGHT: (C)2006,JPO&NCIPI
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