RU2476834C1 - Diffraction polychromator - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: diffraction polychromator has an entrance spectral slit, a concave diffraction grating and a multi-element radiation receiver. At the input of the polychromator there are series-connected zero dispersion double monochromator, having an entrance slit, two concave diffraction gratings, an intermediate concave spherical mirror and an exit slit which is superimposed with the entrance slit of the polychromator.

EFFECT: high level of scattered light and providing high spectrum purity owing to a triple monochromatisation degree with minimum optical components.

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Description

The present invention relates to spectral devices, namely: to diffraction polychromators intended for decomposition into the spectrum of the analyzed radiation.

Known diffraction polychromators designed to operate in various spectral regions (Peysakhson I.V. Optics of spectral instruments, L .: Mashinostroenie, 1975, p. 177).

The level of scattered radiation in them depends on the quality of the optics, the number of optical elements, the dimensions of the optical-mechanical unit, and the degree of monochromatization. It is known that a double degree of monochromatization reduces the level of scattered light by two orders of magnitude. However, these polychromators do not have a sufficiently low level of scattered radiation, which is necessary to solve a certain range of problems.

The closest to the proposed technical essence is the diffraction polychromator of the QE 65000 spectrometer from Ocean Optics (Catalog 2007). Such a polychromator is constructed according to the crossed Czerny-Turner scheme and contains a flat diffraction grating, two concave spherical mirrors playing the role of a collimator and camera lenses, a set of transmission filters that cut off short-wave radiation, an entrance slit, and a multi-element radiation detector with a filter that cuts off radiation of the 2nd and 3rd order spectrum. The level of scattered light in this polychromator is 0.1%, which is very good for a polychromator of such small dimensions (the focal length of the lenses is 101.6 mm), but not always enough.

The aim of the invention is to reduce the level of scattered light and varying the bandwidth of the spectrum without replacing the optical parts (filters).

This goal is achieved due to the fact that in the diffraction polychromator containing a diffraction grating, an entrance slit and a multi-element radiation detector, the diffraction grating is made concave, a double monochromator with zero dispersion is installed at the input of the polychromator, containing an entrance slit, two concave diffraction gratings, an intermediate concave spherical mirror and an exit slit combined with an input slit of a polychromator. Thus, there is a triple degree of monochromatization.

The figure shows the optical scheme of the proposed diffraction polychromator:

4 - entrance slit of a double monochromator;

5 and 8 — two concave diffraction gratings located one below the other;

7 - concave mirror;

8 - exit slit of a double monochromator, it is also the entrance slit of a polychromator;

11 - concave diffraction grating of a polychromator;

12 is a multi-element radiation detector.

Radiation from a light source (for example, laser radiation from source 1 excites luminescence, or Raman radiation in volume 2) through a collective lens 3 and an entrance slit 4 diverges into a concave grating 5, which focuses the diffracted radiation of the spectrum under study onto the surface of a concave spherical mirror 7, and the exciting wavelength focuses into a light trap 6. Mirror 7 reflects the radiation of different wavelengths onto a grating 8 identical to grating 5. Grating 8 mixes the radiation of all wavelengths and Okushiri in the exit slit 10 which is input to the diffraction grating polychromator with a concave 11, a focusing the analyzed spectrum to a multi-element radiation detector 12. The flat mirror 9 is not essential, without gap 10 would be situated below the gap 4.

Calculations showed that the level of scattered light in such a polychromator will decrease by two orders of magnitude compared to the prototype.

Claims (1)

A diffraction polychromator containing an input spectral slit, a diffraction grating, and a multi-element radiation detector, characterized in that, in order to obtain the most pure spectrum with a minimum level of scattered light in the required wavelength range, the diffraction grating is concave, and the polychromator is arranged in series with it double monochromator with zero dispersion containing an entrance slit, two concave diffraction gratings, an intermediate concave spherical mirror and an exit slit, compatible schennuyu with the entrance slit of the polychromator.