Spectroscopic apparatus

摘要

To cover a wide wavelength bandwidth, a spectroscopic apparatus uses three varied line spacing concave diffraction gratings G1 to G3, the corresponding energy ranges for G1, G2, and G3 being 50 to 200, 155 to 350, and 300 to 2200 eV, respectively. In the respective wavelength ranges, the diffraction conditions are satisfied. To provide a high throughput and a high resolution in the respective wavelength regions, the incident angles α1 to α3 for G1 to G3 measured from the normal line of the diffraction grating are specified to be α1<α2<α3. Presupposing the normal lines of all diffraction gratings are superposed upon a common normal line, in order to meet α1<α2<α3, the center positions Δ1 to Δ3 for G1 to G3 are set on the normal line (as Δ1<Δ2<Δ3). From G1 to G3, one diffraction grating can be selected.

主权项

1. A spectroscopic apparatus, including a plurality of varied line spacing diffraction gratings differing in range of wavelengths to be accommodated, one varied line spacing diffraction grating being selected from among the plurality of varied line spacing diffraction gratings for obtaining a desired wavelength of output light, an incident ray emitted from a light source entering the one varied line spacing diffraction grating, and a diffracted ray focusing onto an image surface common to all the varied line spacing diffraction gratings, the spectroscopic apparatus comprising a selection means for selecting the one varied line spacing diffraction grating to install it in a position where the incident ray is to be entered,
wherein, in selecting the one varied line spacing diffraction grating from among the plurality of varied line spacing diffraction gratings, the selection means treats the normal line passing through the center of the groove plane of the respective varied line spacing diffraction gratings as one to be superposed upon a common normal line, and in case where the light source is on the upper side of the groove plane, selects the one varied line spacing diffraction grating and installs it such that the smaller the value of the minimum wavelength to be accommodated, the higher the position at which the groove plane is set.