Echelon spectroscope

Abstract

An echelle spectrometer has one or more echelle diffraction gratings, one or more separating devices for separating dispersed light into fractions according to different diffraction orders, and one or more imaging devices such as imaging mirrors, but Only one image detector is used. The entire wavelength range is divided into several smaller ranges, and the spectral light parts emitted from the light sources corresponding to these separated wavelength ranges respectively travel along different optical paths, but the formed images all fall on the same image detector. A shutter is used to selectively allow passage of one of the spectral light portions corresponding to one of the different wavelength ranges.

Description

technical field [0001] The present invention relates to a spectrometer for use in different types of spectroscopic analysis instruments such as emission or absorption spectroscopic analysis, and more particularly, the present invention relates to an echelle spectrometer using an echelon diffraction grating. Background technique [0002] As the light dispersing element in the step spectrometer, the echelon diffraction grating is usually designed to have a larger blaze angle θ than the ordinary echelon diffraction grating, and its free spectral range is narrower on the short wavelength side and wider on the long wavelength side, so it can provide stronger dispersion and resolving power. On the other hand, it is known that it is better to use an image detector including a CCD (Charge Coupled Device) or a photodiode matrix as a photodetection element to detect the spectral light split by the diffraction grating, because the spectral light of each wavelength It is detected by th...

AI Technical Summary

Problems solved by technology

If the image detector is shifted from one position to another, the mechanism to achieve this shift requires high precision, that is, in order to maintain the reproducibility of the position of the spectral image, it should be in both horizontal and vertical positions. direction has an accuracy no greater than a few microns. This increases the overall cost of the device

Moreover, because the displacement is done mechanically, there will be a stability problem. If the position accuracy of the image detector moving back and forth in the direction of the wavelength is not enough, the actual measurement result will be as follows: Figure 7A , Figure 7B , Figure 7C As shown, for example, due to the offset, as long as the actual measured wavelength is slightly different (with errors of Δλ and Δλ' for the original wavelength λi), different intensities will be measured (with ΔI and ΔI for the original measured intensity Ii ' error)

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