| 摘要 |
PURPOSE:To enable the covering a broad wavelength with a high sensitivity to a certain extent by setting several kinds of diffraction gratings varied in the blaze wavelength so that sharing wavelength ranges of the respective diffraction gratings give specified multiplied values of blaze wavelengths of the diffraction gratings. CONSTITUTION:In the embodiment, three kinds of diffraction gratings having the same grating constant and with blaze wavelengths of 0.2, 0.53 and 1.4mum respectively and the sharing wavelength ranges of the respective diffraction gratings are set at 0.14-0.37, 0.37-0.98 and 0.93-2.59mum with respect to the blaze wavelengths of 0.2, 0.53 and 1.4mum correspondingly. The range of the sharing wavelength area is set at (0.65-0.7)lambdab-(1.7-2.0)lambdab when the blaze wavelength is put at lambdab. In this embodyment the relative diffraction intensity with respect to the entire measuring wavelength area is as illustrated. The grating switching waves are 0.37 and 0.98mum where the relative diffraction intensity is a half of that at the blaze angle while the relative diffraction intensity is held within the range of 0.5-1 from 0.14-2.59mum in the wavelength. |
