CN114279570B

CN114279570B - Spectrometer mounting and adjusting system

Info

Publication number: CN114279570B
Application number: CN202111490571.4A
Authority: CN
Inventors: 周辉; 袁丁; 吴红彦; 夏征
Original assignee: Ht Nova Co ltd
Current assignee: Ht Nova Co ltd
Priority date: 2021-12-08
Filing date: 2021-12-08
Publication date: 2023-11-28
Anticipated expiration: 2041-12-08
Also published as: CN114279570A

Abstract

The invention relates to the technical field of spectrometers, in particular to an assembling and adjusting system of a spectrometer, which comprises a chip, and a preset light source, a first light mirror system, a Fabry-Perot interferometer and a second light mirror system which are sequentially arranged.

Description

Spectrometer mounting and adjusting system

Technical Field

The invention relates to the technical field of spectrometers, in particular to an assembling and adjusting system of a spectrometer.

Background

Spectrometer: the spectrometer is also called a spectrometer, the most common is a direct-reading spectrometer, and a device for measuring the intensities of different wavelength positions of spectral lines by using a light detector such as a photomultiplier tube consists of an incident slit, a dispersion system, an imaging system and one or more emergent slits, and the electromagnetic radiation of a radiation source is separated into a required wavelength or wavelength region by using a dispersion element, and the intensity measurement is performed at a selected wavelength (or a certain wave band is scanned). Spectrometers are classified into monochromators and polychromators.

The spectral resolution is an important index for measuring the performance of the spectrometer, and the higher the spectral resolution is, the more minute spectral information in the spectrum can be identified. In measuring spectral resolution, the industry generally uses the full width at half maximum of natural light sources, specifically:

1) Spectral resolution: spectral resolution refers to the ability to decompose spectral features, spectral bands, into separate components. What spectral resolution is required by analysts and researchers is determined by the particular problem they face. For example, conventional analysis for basic sample identification requires only low/medium spectral resolution. In contrast, high resolution is often required for the characterization of polymorphs and crystallinity, as these phenomena only appear as very subtle changes in raman spectra, which are not observed in low resolution experiments;

2) The grating equation: d (sin i+sin θ) =mλ, where d represents a grating constant, i and θ represent an incident angle and a diffraction angle by resolution, m is a diffraction order, and λ represents an incident wavelength. 101 and 102 represent incident light, 103 and 104 represent outgoing light after the incident light is diffracted by the grating, and 105 represents the grating, as shown in fig. 1.

3) The full width at half maximum, abbreviated as FWHM (FWHM is an abbreviation of Full Width at Half Maxima), also known as the half width, half peak width, area width and area half width, is a term of spectral analysis, and refers to the width of a peak at half of the peak of a spectrum, that is, a straight line parallel to the bottom of the peak through the middle point of the peak, the distance between the two points where the straight line intersects both sides of the peak, is generally used to measure the spectral resolution of a spectrometer, as shown in fig. 2, the width of the peak at half of the peak of the spectrum, that is, a straight line parallel to the bottom of the peak through the middle point of the peak, and the distance between the straight line and the two points where the two sides of the peak intersect, where D in fig. 2 is the full width at half maximum, is used to measure the spectral resolution.

When designing a spectrometer, as shown in fig. 3, after the complex color light is spatially filtered by the slit 1, the complex color light is incident on the first concave mirror 2, the first concave mirror 2 collimates the complex color light into parallel complex color light, and irradiates the parallel complex color light on the grating 3, the grating 3 disperses the parallel complex color light into various monochromatic lights according to different wavelengths, the various monochromatic lights are imaged on the optical sensor 5 through the second concave mirror 4, P1, P2 and P3 respectively represent the convergence positions of the monochromatic lights with different wavelengths, and when the adjustment errors of the first concave mirror 2, the grating 3 and the second concave mirror 4 are not considered, the position of the optical sensor 5 is strictly at the design position, and then the resolution of the various wavelengths is the design value.

However, in the actual adjustment process, the first concave mirror 2, the grating 3, the second concave mirror 4 and the optical sensor 5 cannot be completely located at the ideal design position, taking the inclination of the position of the optical sensor 5 as an example, as shown in fig. 4, when the optical sensor 5 deviates from the design position, the image plane of a dotted line indicates the ideal position, and when the optical sensor 5 rotates around the point P2, the resolution of other points such as the point P4 and the point P5 is reduced except the single-color light energy converged to the point P2 guarantees the resolution, i.e. the required full-peak height is increased, besides the deflection error as shown in fig. 4, the defocus error exists, and even the deflection error and the defocus coexist.

Currently, in order to objectively measure the spectral resolution of the full spectrum as much as possible, it is common practice to find several points in the whole spectrum to measure the full width at half maximum, as shown in fig. 3, and simultaneously measure the full width at half maximum of wavelengths at positions P1, P2 and P3, where P1, P2 and P3 are used to represent the resolutions of the low band, the middle band and the long band in the whole spectrum, and most commonly, the Ar (argon) light source spectrum is applied, as shown in fig. 5, but in the conventional method, even if several points are found, the spectral resolution of the spectrometer cannot be measured in the full spectrum, and the adjustment of the spectrometer cannot be guided.

Disclosure of Invention

The invention aims to solve the technical problem of providing an assembling and adjusting system of a spectrometer aiming at the defects of the prior art.

The technical scheme of the adjustment system of the spectrometer is as follows:

the system comprises a chip, and a preset light source, a first light mirror system, a Fabry-Perot interferometer and a second light mirror system which are sequentially arranged, wherein the free spectral range FSR of the Fabry-Perot interferometer is smaller than the theoretical spectral resolution of a spectrometer to be assembled;

the first light mirror system collimates the multi-color light emitted by the preset light source into first parallel light and irradiates the first parallel light to the Fabry-Perot interferometer;

the first parallel light passes through the Fabry-Perot interferometer to obtain second parallel light, and the second parallel light is emitted to the second light mirror system;

the second light mirror system converges the second parallel light to obtain converged light, and first spectrum data of the converged light are obtained through a calibrated spectrometer;

the chip is used for:

obtaining a first data result comprising the full width at half maximum corresponding to each preset spectrum peak position according to the first spectrum data;

obtaining a second data result comprising the full width at half maximum corresponding to each preset spectrum peak position according to the second spectrum data, wherein the complex color light emitted by the preset light source is emitted to the spectrometer to be assembled to obtain the second spectrum data;

and comparing the first data result with the second data result, so that a user can adjust the spectrometer to be adjusted according to the comparison result until the deviation between the second data result and the first data result meets the preset condition.

The spectrometer debugging system has the following beneficial effects:

when the frequency of the first parallel light meets the resonance condition of the Fabry-Perot interferometer, the spectrum of the transmitted second parallel light has a very high peak value, so that the very high peak value appears in the first spectrum data of the converged light, the sensitivity to the subtle change sent by a preset light source can be improved, and the free spectrum range FSR of the designed Fabry-Perot interferometer is smaller than the theoretical spectrum resolution of the spectrometer to be adjusted, so that the adjusting system of the spectrometer has higher spectrum resolution, a first data result comprising the full width half maximum corresponding to each preset spectrum peak position is obtained according to the first spectrum data as a standard, and a part to be adjusted is more convenient for a user to determine according to the comparison result between the first data result and the second data result. For example, it is convenient for a user to adjust the components of the respective spectroscopic apparatus, such as the first concave mirror 2, the grating 3 and the second concave mirror 4, and the optical sensor 5, the adjustment dimensions including the position and the deflection angle of the components. In general, the first concave mirror 2, the grating 3, the second concave mirror 4 and the optical sensor 5 do not need to be adjusted at the same time, and the combination of the adjustment parts and the adjustment dimension can be reduced according to the comparison result.

On the basis of the scheme, the adjustment system of the spectrometer can be improved as follows.

Further, the first mirror system is a first convex lens.

Further, the second mirror system is a second convex lens.

Further, the preset light source is a halogen tungsten lamp.

The beneficial effects of adopting the further scheme are as follows: the halogen tungsten lamp is a multipurpose light source, is most suitable for a spectrometer with the wave band of 360nm-2000nm, has long service life of a bulb and is stable in output.

Drawings

FIG. 1 is a schematic diagram of a grating equation

FIG. 2 is a schematic diagram of full width at half maximum;

FIG. 3 is one of the schematic optical paths of the spectrometer;

FIG. 4 is a second schematic view of the optical path of the spectrometer;

FIG. 5 is an argon lamp light source spectrum;

FIG. 6 is a schematic diagram of a tuning system of a spectrometer according to an embodiment of the present invention;

FIG. 7 is a graph of the spectral power distribution of a tungsten halogen lamp;

FIG. 8 is a second schematic diagram of a tuning system of a spectrometer according to an embodiment of the present invention;

FIG. 9 is a schematic illustration of a first spectrum;

FIG. 10 is a schematic view of a partially enlarged spectrum;

FIG. 11 is a schematic illustration of a spectrum in the 750-1000nm band;

fig. 12 is a schematic view of the optical path of the spectrometer to be tuned.

Detailed Description

As shown in fig. 6, an adjustment system of a spectrometer according to an embodiment of the present invention includes: the optical system comprises a chip, and a preset light source 6, a first light mirror system 7, a Fabry-Perot interferometer 8 and a second light mirror system 9 which are sequentially arranged, wherein the free spectral range FSR of the Fabry-Perot interferometer 8 is smaller than the theoretical spectral resolution of a spectrometer to be adjusted;

the halogen tungsten lamp 60 is selected as the preset light source 6, the halogen tungsten lamp 60 is a multipurpose light source, the halogen tungsten lamp 60 is most suitable for a spectrometer with a wave band of 360nm-2000nm, the service life of a bulb is long, the output is continuous and stable, the spectrum energy distribution of the polychromatic light emitted by the halogen tungsten lamp 60 is shown in fig. 7, and other light sources can be selected according to the actual situation.

The first light mirror system 7 collimates the complex-color light emitted by the preset light source 6 into first parallel light and irradiates the first parallel light to the fabry-perot interferometer 8;

the first parallel light passes through the fabry-perot interferometer 8 to obtain second parallel light, and the second parallel light is emitted to the second light mirror system 9;

the second optical lens system 9 converges the second parallel light to obtain a converged light, and obtains first spectrum data of the converged light through a calibrated spectrometer, wherein P in fig. 6 represents an exit port of the converged light, and the calibrated spectrometer receives the converged light to obtain the first spectrum data of the converged light;

the chip is used for:

obtaining a second data result comprising the full width at half maximum corresponding to each preset spectrum peak position according to the second spectrum data, wherein the complex color light emitted by the preset light source 6 is emitted to the spectrometer to be assembled to obtain the second spectrum data;

The device capable of collimating the incident multi-color light into parallel light on the market may be selected as the first optical lens system 7, or a convex lens may be selected as the first optical lens system 7, and the convex lens as the first optical lens system 7 is labeled as the first convex lens 70, that is, the first optical lens system 7 is the first convex lens 70.

The device capable of converging the incident parallel light on the market may be selected as the second optical lens system 9, or a convex lens may be selected as the second optical lens system 9, and the convex lens as the second optical lens system 9 is labeled as the second convex lens 90, that is, the second optical lens system 9 is the second convex lens 90.

It will be appreciated that the light emitted by the preset light source 6 is polychromatic, and therefore, the first parallel light, the second parallel light and the converging light are polychromatic.

As shown in fig. 8, a tungsten halogen lamp 60 is selected as the preset light source 6, a first convex lens 70 is selected as the first mirror system 7, and a second convex lens 90 is selected as the second mirror system 9, specifically:

the first convex lens 70 collimates the complex-color light emitted by the halogen tungsten lamp 60 into a first parallel light and irradiates the first parallel light to the fabry-perot interferometer 8, the fabry-perot interferometer 8 comprises two high-reflectivity flat mirrors 80, the two high-reflectivity flat mirrors 80 form the fabry-perot interferometer 8, the distance between the two flat mirrors 80 is h, the refractive index between the two flat mirrors 80 is n, and if the light is in air, the refractive index n can be approximately the refractive index in vacuum, namely n=1;

the first parallel light passes through the fabry-perot interferometer 8 to obtain second parallel light, and the second parallel light is emitted to the second convex lens 90;

the second convex lens 90 converges the second parallel light to obtain a converged light, and obtains first spectrum data of the converged light through a calibrated spectrometer, where P in fig. 6 represents an exit port of the converged light, the calibrated spectrometer receives the converged light to obtain first spectrum data of the converged light, and obtains a first spectrum of the converged light according to the first spectrum data, as shown in fig. 9, and locally amplifies a spectrum with a wavelength in a range of 360nm-2000nm in the first spectrum shown in fig. 9, as shown in fig. 10.

As can be seen from fig. 9 and 10, the pulse spectrum peak is rich in the range of 360-2000nm, and the distance between two adjacent peaks, namely the free spectral range FSR, is only related to the fabry-perot interferometer 8:

by adjusting the distance h between two high reflectivity mirrors 80, the desired FSR can be obtained, which should be designed to be smaller than the theoretical resolution value of the spectrometer to be evaluated, i.e. the spectrometer to be tuned, specifically expressed in: the value of the free spectral range FSR is smaller than the theoretical full width at half maximum of the spectrometer to be tuned.

It can be understood that the distance between any two adjacent peaks can be selected as the free spectrum range FSR, and the average value of the distances between multiple groups of two adjacent peaks can be selected as the free spectrum range FSR, so that the difference between the values of the free spectrum range FSR determined by the two modes is extremely small.

The value of the free spectral range FSR is smaller than the theoretical full width at half maximum of the spectrometer to be assembled, and the free spectral range FSR can be set to be 2.5nm, and the theoretical full width at half maximum of the spectrometer to be assembled is 2.8nm.

According to the first spectrum data, a first data result comprising the full width at half maximum corresponding to each preset spectrum peak position is obtained, after a spectrum diagram is obtained, an algorithm is called to obtain each preset spectrum peak position and the full width at half maximum corresponding to each preset spectrum peak position, conventional commercial software can be realized, and a specific extraction process is not described;

and (3) emitting the multi-color light emitted by the halogen tungsten lamp 60 to the spectrometer to be modulated to obtain second spectrum data, obtaining a second data result comprising the full width at half maximum corresponding to each preset spectrum peak position according to the second spectrum data, wherein the spectrum of the 750-1000nm wave band is shown in fig. 11, and extracting part of preset spectrum peak positions and the full width at half maximum corresponding to each extracted preset spectrum peak position from the spectrum data corresponding to fig. 11 to obtain a second data result as shown in the following table 1.

Table 1:

preset spectral peak position (nm)	764	768	772	775	779	783	764	768	772
										Full width at half maximum (nm)	2.69	2.77	2.78	2.77	2.73	2.68	2.68	2.77	2.78

If a part of preset spectrum peak positions and half-peak full widths corresponding to each extracted preset spectrum peak position are extracted from the first spectrum data, obtaining a first data result, as shown in the following table 2;

table 2:

preset spectral peak position (nm)	764	768	772	775	779	783	764	768	772
										Full width at half maximum (nm)	2.68	2.76	2.79	2.76	2.72	2.65	2.65	2.78	2.80

Comparing the first data result with the second data result, specifically comparing the table 1 with the table 2, and obtaining the comparison result as follows: the full width at half maximum corresponding to the preset spectral peak position in the first data result and the full width at half maximum corresponding to the preset spectral peak position in the second data result have small differences, which means that the whole image plane is at the design position, namely the current positions of the first concave reflector 2, the grating 3, the second concave reflector 4 and the optical sensor 5 have extremely small differences from the ideal design positions, and in this case, the deviation between the second data result and the first data result can be considered to meet the preset condition, and the spectrometer to be assembled and adjusted is not assembled any more;

the preset conditions specifically may be: the full width half maximum of the preset spectrum peak position in the second data result and the full width half maximum of the corresponding preset spectrum peak position in the first data result are both within preset errors, for example, the preset errors are 1% or 0.5%, and preset conditions can be set according to actual conditions.

When the comparison result is that: if the full width half maximum of each preset peak position in the second data result is larger than the full width half maximum of the corresponding preset peak position in the first data result, the image surface may be out of focus, as shown in fig. 12, the dotted line position in fig. 12 represents the ideal image surface of the optical sensor 5, that is, the ideal position, and the solid line position represents the actual position of the optical sensor 5, at this time, it may be primarily determined that the actual position of the optical sensor 5 deviates from the ideal position, that is, by means of the comparison result, the user is helped to determine the component to be adjusted, that is, the optical sensor 5, without large-area searching, time and effort are saved, and the adjustment efficiency is improved.

When the comparison result is that: when the spectrum resolution of the full spectrum is low, the whole out-of-focus of the image plane may be prompted, the image plane focusing process may be preferentially considered during the adjustment, the image plane focusing process may be mainly considered to adjust the second concave mirror 4 and the optical sensor 5, and appropriate translation may be performed without performing deflection adjustment. Generally, the amount of adjustment of the second concave mirror 4 is set to be larger, so that the problem of out-of-focus image surface can be better solved by translating the second concave mirror 4.

When the comparison result is that: when the spectrum resolution of the full spectrum is low and the full spectrum is irregular, namely, the resolution of each point of the full spectrum is randomly distributed and the resolution is randomly staggered, but the whole is low, two possible reasons are generally suggested at the moment, namely, the first concave mirror 2 is not aligned, the first concave mirror acts to collimate the complex color light incident from the slit 1 into parallel light, if the first concave mirror 2 is not aligned (the position is not aligned and comprises inclination, dislocation and the like), the collimation effect is poor, once the collimation effect is poor, the complex color light incident to the grating 3 does not meet the conventional grating equation any more, the spectrum resolution is poor and irregular, at the moment, the first concave mirror 2 needs to be readjusted, and even the component needs to be reinstalled in serious cases. The second possible reason is that the grating 3 is not positioned correctly and the grating 3 is typically mounted together with the second concave mirror 4.

As shown in fig. 4, when the sensor 5 rotates around the point P2 to deviate from the ideal plane, the resolution of the spectrum will be lower at both ends of the spectrum, and the resolution of the rotation point is normal, so that the image plane needs to be rotated correspondingly during the adjustment. Therefore, the method for evaluating the resolution of the full-spectrum spectrometer can guide the adjustment of the spectrometer.

When the frequency of the first parallel light meets the resonance condition of the fabry-perot interferometer 8, the spectrum of the transmitted second parallel light has a very high peak value, so that the very high peak value appears in the first spectrum data of the converged light, the sensitivity to the subtle changes sent by the preset light source 6 can be improved, and the free spectrum range FSR of the designed fabry-perot interferometer 8 is smaller than the theoretical spectrum resolution of the spectrometer to be adjusted, so that the adjusting system of the spectrometer has higher spectrum resolution, the first data result comprising the half-peak full width corresponding to each preset spectrum peak position obtained according to the first spectrum data is used as a standard, and the user can determine the components to be adjusted more conveniently according to the comparison result between the first data result and the second data result.

In the present disclosure, the terms "first," "second," and "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying a number of technical features being indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.

Claims

1. The system for adjusting the spectrometer is characterized by comprising a chip, and a preset light source, a first light mirror system, a Fabry-Perot interferometer and a second light mirror system which are sequentially arranged, wherein the free spectral range FSR of the Fabry-Perot interferometer is smaller than the theoretical spectral resolution of the spectrometer to be adjusted;

the chip is used for:

2. The tuning system of claim 1, wherein the first optical lens system is a first convex lens.

3. The tuning system of a spectrometer of claim 1 or 2, wherein the second optical lens system is a second convex lens.

4. The tuning system of a spectrometer of claim 1 or 2, wherein the predetermined light source is a halogen tungsten lamp.