| 摘要 |
PROBLEM TO BE SOLVED: To obtain a refraction optical device which hardly lowers the diffraction efficiency, even in the use of a diffractive optical device, having such a shape that the curvature radius of the enveloping face of each refraction grating is small. SOLUTION: In the refractive optical device, in which refraction gratings 6 and 7 made of materials that are different in diversion from each other are bonded together one on the other and refraction efficiency in specific order is increased in the entire area of a wavelength used, the enveloping faces on which the grating leading ends 6b and 7b of the refraction gratings 6 and 7, respectively, are arranged in series are curved faces 9 and 10. The absolute values of the curvature radii of the enveloping faces are made greater than the absolute values of the curvature radii of the grating faces 11 and 12 of the gratings 6a and 7a, respectively. COPYRIGHT: (C)2006,JPO&NCIPI
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