| 摘要 |
PROBLEM TO BE SOLVED: To provide a diffraction grating element that can eliminate the need for a temperature control mechanism or simplify it. SOLUTION: The diffraction grating element 1 has a diffraction grating formed on a 1st surface 10A of a transparent flat plate 10 having the 1st surface 10A and a 2nd surface 10B which are in contact with media 21 and 22, respectively, and parallel to each other. The diffraction grating formed on the 1st surface 10A has its grating direction in parallel to a (y) axis and also has unevenness periodically formed in cyclesΛalong an (x) axis. The media 21 and 22 are, for example, air and the transparent flat plate 10 is made of, for example, quartz glass. At some temperature in a temperature range of -20 to +80°C, the sum of the coefficient of linear expansion of the cyclesΛof the diffraction grating and temperature coefficients of refractive indexes of the media 21 and 22 is 0. COPYRIGHT: (C)2005,JPO&NCIPI |
