Temperature-compensated spectrometer

摘要

The invention relates to a spectrometer comprising a hollow main optical body having at least one light channel, a light source, a diffraction grating having a grating central point, a light inlet opening, and a detector unit, which are arranged in such a way that the focal curve of the spectrometer satisfies the back focus equation. In order to create a spectrometer having sufficient spectral resolution from a low-price, light, and easy-to-process material, which spectrometer is able to operate in a large temperature interval even without thermostatic control, according to the invention the light inlet opening is arranged on a compensation body, the compensation body is arranged in the light channel and fastened to the main optical body between the light source and the diffraction grating, and the compensation body is dimensioned in such a way that the compensation body changes the distance between the light inlet opening and the grating central point when the main optical body thermally expands.

主权项

1. A spectrometer, comprising:
a hollow main optical body having at least one light channel; a light source; a diffraction grating having a grating central point; a light inlet opening; and a detector unit, which are arranged so that a focal curve of the spectrometer satisfies a back focus equation:cos2⁢αLA-cos⁢⁢αR+cos2⁢βLB-cos⁢⁢βR-n⁢⁢λ⁢⁢K=0where
α is an angle of incidence, β is a diffraction angle, LA is an inlet back focal length, LB is an outlet back focal length, R is a grating radius indicative of a radius of curvature of a spherical grating surface, n is a diffraction order, λ is a wavelength at the diffraction angle β and K is a spherical grating constant, and further comprising:
a compensation body, the light inlet opening disposed on the compensation body, the compensation body disposed in the light channel and fixed on the main optical body between the light source and the diffraction grating, the compensation body configured so that during thermal expansion of the main optical body the compensation body changes the distance between the light inlet opening and the grating central point such that a shift of the focal curve is corrected by overcompensating the thermal expansion of the main optical body by expansion of the compensation body.