| 摘要 |
PROBLEM TO BE SOLVED: To provide a spectrometry instrument having such reliability that a spectrum position does not move within the surface of a detector against the temperature change, a compact size and light weight in the spectrograph type spectrometry instrument using a concave holography diffraction grating. SOLUTION: The spectrometry instrument is composed of a light source to be measured; the concave holography diffraction grating 3; and a telecentric correcting lens 8 telecentrically focusing diffracted light 5 from a diffraction grating on a spectrum converging surface. By this constitution, spectrum light is made vertically incident on a spectrum image formation surface, move of a spectrum on a light receiving surface is prevented even if a light receiving element in the optical axis direction is moved by temperature change, a converging action which is possessed by the concave holography diffraction grating 3 is actively employed, and the spectrometry instrument with a compact size and light weight can be developed without largely increasing the distance from the grating of only the concave diffraction grating to the spectrum converging surface.
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