CN114279570A

CN114279570A - Installation and adjustment system of spectrometer

Info

Publication number: CN114279570A
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: 2022-04-05
Anticipated expiration: 2041-12-08
Also published as: CN114279570B

Abstract

The invention relates to the technical field of spectrometers, in particular to an installation and adjustment system of a spectrometer, which comprises a chip, and a preset light source, a first optical mirror system, a Fabry-Perot interferometer and a second optical mirror system which are sequentially arranged, wherein when the frequency of first parallel light meets the resonance condition of the Fabry-Perot interferometer, the frequency spectrum of the second parallel light transmitted by the first parallel light has a very high peak value, so that the very high peak value appears in first spectral data of converged light, and the sensitivity of the first spectral data to fine variation emitted by the preset light source can be improved, it is more convenient for the user to determine the components that need to be adjusted.

Description

Installation and adjustment system of spectrometer

Technical Field

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

Background

A spectrometer: the spectrometer, also known as a spectrometer, most commonly a direct-reading spectrometer, uses a photo-detector such as a photomultiplier tube to measure the intensities of the spectral lines at different wavelength positions, and consists of an entrance slit, a dispersion system, an imaging system and one or more exit slits, and uses a dispersion element to separate the electromagnetic radiation of a radiation source into the desired wavelength or wavelength region and to measure the intensity at the selected wavelength (or scan a band). Spectrometers are divided 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 tiny spectral information in the spectrum can be identified. In measuring spectral resolution, the industry typically employs the full width at half maximum of a natural light source, specifically:

1) spectral resolution: spectral resolution refers to the ability to decompose spectral features, bands, into separate components. What spectral resolution is required by analysts and researchers is determined by the specific problems they are faced with. 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 polymorphism as well as crystallinity, as these phenomena only show very subtle changes in raman spectra, which are not observed in low resolution experiments;

2) the grating equation: d (sin i + sin θ) ═ m λ, where d represents the grating constant, i and θ resolve the incident and diffraction angles, m is the diffraction order, and λ represents the incident wavelength. 101 and 102 denote incident light, 103 and 104 denote outgoing light after the incident light is diffracted by the grating, and 105 denotes 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 maximum), also called Full Width at Half maximum, area Width and area Half maximum, is a term of spectral analysis, and refers to the peak Width at Half maximum of the spectrum, i.e. a straight line parallel to the peak bottom is drawn through the midpoint of the peak height, and the distance between the straight line and two intersecting points on both sides of the peak is usually used to measure the spectral resolution of the spectrometer, as shown in fig. 2, the peak Width at Half maximum, i.e. a straight line parallel to the peak bottom is drawn through the midpoint of the peak height, and the distance between the straight line and two intersecting points on both sides of the peak is drawn, and D in fig. 2 is the Full Width at Half maximum, and is used to measure the spectral resolution.

When designing a spectrometer, as shown in fig. 3, after being spatially filtered by a slit 1, the polychromatic light is incident on a first concave mirror 2, the first concave mirror 2 collimates the polychromatic light into parallel polychromatic light, and irradiates the parallel polychromatic light on a grating 3, the grating 3 disperses the parallel polychromatic light into monochromatic lights according to the size of the wavelength, the monochromatic lights are imaged on an optical sensor 5 through a second concave mirror 4, the positions of the monochromatic lights with different wavelengths are represented by P1, P2 and P3, 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 in the design position, and the resolution of each wavelength 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, for example, the position of the optical sensor 5 is inclined, as shown in fig. 4, when the optical sensor 5 deviates from the design position, the dotted image plane represents the ideal position, and the optical sensor 5 rotates around the point P2, so that the resolution of other points such as P4 and P5 is reduced, that is, the total height of the half peak is increased, besides the resolution of the monochromatic light converged to the point P2, the defocus error exists, and even the yaw error and the optical sensor exist simultaneously, as shown in fig. 4.

At present, in order to measure the spectral resolution of the full spectrum as objectively as possible, it is a conventional practice to find several points in the whole spectrum range to measure the full width at half maximum, as shown in fig. 3, and simultaneously measure the full widths at half maximum of the wavelengths at the positions P1, P2 and P3, respectively, P1, P2 and P3 represent the resolution of the low-wavelength band, the medium-wavelength band and the long-wavelength band in the whole spectrum range, and most commonly, the spectrum of the Ar (argon) lamp light source is applied, as shown in fig. 5.

Disclosure of Invention

The invention provides an adjusting system of a spectrometer aiming at the defects of the prior art.

The technical scheme of the assembling and adjusting system of the spectrometer is as follows:

the device comprises a chip, and a preset light source, a first optical mirror system, a Fabry-Perot interferometer and a second optical 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 first optical mirror system collimates the polychromatic light emitted by the preset light source into first parallel light and emits the first parallel light to the Fabry-Perot interferometer;

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

the second optical lens system converges the second parallel light to obtain converged light, and first spectrum data of the converged light is obtained through the calibrated spectrometer;

the chip is used for:

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

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

The installation and adjustment system of the spectrometer has the following beneficial effects:

when the frequency of the first parallel light meets the resonance condition of the Fabry-Perot interferometer, the frequency spectrum of the second parallel light transmitted by the first 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 fine change emitted 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. For example, it is convenient for the user to adjust the components of the corresponding spectroscopic instrument, 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. Generally, 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 components 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 further improved as follows.

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

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

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

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

Drawings

FIG. 1 is a schematic diagram of a grating equation

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

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

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

FIG. 5 is an argon lamp source spectrum;

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

FIG. 9 is a schematic of a first spectrum;

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

FIG. 11 is a diagram showing the spectrum in the 750-and 1000-nm bands;

fig. 12 is a schematic diagram of the optical path of the spectrometer to be loaded.

Detailed Description

As shown in fig. 6, an assembling system of a spectrometer according to an embodiment of the present invention includes: the device comprises a chip, and a preset light source 6, a first optical mirror system 7, a Fabry-Perot interferometer 8 and a second optical 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 arranged;

the halogen tungsten lamp 60 can be 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 the bulb is long, the output is continuous and stable, the spectral energy distribution of polychromatic light emitted by the halogen tungsten lamp 60 is shown in figure 7, and other light sources can be selected according to actual conditions.

The first optical mirror system 7 collimates the polychromatic light emitted by the preset light source 6 into first parallel light, and emits the first parallel light to the fabry-perot interferometer 8;

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

the second optical mirror system 9 converges the second parallel light to obtain converged light, and a calibrated spectrometer is used to obtain first spectral data of the converged light, where P in fig. 6 represents an exit port of the converged light, and the calibrated spectrometer receives the converged light to obtain the first spectral data of the converged light;

the chip is used for:

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

A device capable of collimating the incident polychromatic light into parallel light on the market can be used as the first optical lens system 7, or a convex lens can be used as the first optical lens system 7, and the convex lens used as the first optical lens system 7 is marked as a first convex lens 70, that is, the first optical lens system 7 is the first convex lens 70.

A device capable of converging incident parallel light on the market can be selected as the second optical lens system 9, a convex lens can also be selected as the second optical lens system 9, the convex lens serving as the second optical lens system 9 is marked as a second convex lens 90, and the second optical lens system 9 is the second convex lens 90.

It is understood that the light emitted by the light source 6 is a polychromatic light, and thus, the first parallel light, the second parallel light and the converging light are all polychromatic lights.

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

the first convex lens 70 collimates the polychromatic light emitted by the halogen tungsten lamp 60 source into a first parallel light, and emits the first parallel light to the fabry-perot interferometer 8, the fabry-perot interferometer 8 includes 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 first convex lens is located in the air, the refractive index n can be approximate to the refractive index in the vacuum, that is, n is 1;

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

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

From fig. 9 and fig. 10, it can be seen that there are abundant pulse spectrum peaks in the range of 360-2000nm, and the distance between two adjacent peaks is the free spectrum range FSR, which is only related to the fabry-perot interferometer 8:

by adjusting the distance h between the two plane mirrors 80 with high reflectivity, a 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 adjusted, and is specifically embodied as follows: the value of the free spectral range FSR is less than the theoretical full width at half maximum of the spectrometer to be loaded.

It is understood that the distance between any two adjacent peaks can be used as the free spectral range FSR, or the average value of the distances between a plurality of groups of two adjacent peaks can be used as the free spectral range FSR, and the values of the free spectral range FSR determined by the two methods are very small.

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

Obtaining a first data result comprising the full width at half maximum corresponding to each preset spectral peak position according to the first spectral data, and calling an algorithm to obtain the full width at half maximum corresponding to each preset spectral peak position after obtaining a spectrogram, wherein conventional commercial software can be realized, and the specific extraction process is not explained;

the complex color light emitted by the halogen tungsten lamp 60 is emitted to the spectrometer to be adjusted to obtain the second spectrum data, the second data result comprising the full width at half maximum corresponding to each preset spectral peak position is obtained according to the second spectrum data, the spectrum of the 750-plus-1000 nm wave band is shown in fig. 11, and part of the preset spectral peak positions and the full width at half maximum corresponding to each extracted preset spectral peak position are extracted from the spectrum data corresponding to fig. 11 to obtain the second data result, which is shown in table 1 below.

Table 1:

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

If part of preset spectral peak positions and full width at half maximum corresponding to each extracted preset spectral peak position are extracted from the first spectral data, a first data result is obtained, as shown in table 2 below;

table 2:

preset spectral peak position (nm)	764	768	772	775	779	783	764	768	772
										Full width 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 table 1 and table 2, and obtaining a comparison result as follows: the difference between the full width at half maximum corresponding to the preset spectrum peak position in the first data result and the full width at half maximum corresponding to the preset spectrum peak position in the second data result is very small, which indicates that the image plane is entirely at the design position, i.e. the difference between the current positions of the first concave mirror 2, the grating 3, the second concave mirror 4 and the optical sensor 5 and the respective ideal design positions is very small, under the condition, 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 adjusted is not adjusted;

the preset conditions may specifically be: the error between the full width at half maximum of the preset peak position in the second data result and the full width at half maximum of the corresponding preset peak position in the first data result is within a preset error, for example, the preset error is 1% or 0.5%, and the preset condition may also be set according to the actual situation.

When the comparison result is: the full width at half maximum of each preset spectral peak position in the second data result is larger than the full width at half maximum of the corresponding preset spectral peak position in the first data result, so that defocusing may occur on the image plane, specifically, as shown in fig. 12, the dotted line position in fig. 12 represents an ideal image plane, i.e., an ideal position, of the optical sensor 5, and the solid line position represents an actual position of the optical sensor 5, at this time, it can be preliminarily determined that the actual position of the optical sensor 5 deviates from the ideal position, that is, by means of the comparison result, it is helpful for the user to determine a component to be adjusted, i.e., the optical sensor 5, which does not need to search in a large area, saves time and effort, and improves the installation and adjustment efficiency.

When the comparison result is: when the full-spectrum spectral resolution is low, the whole defocusing of the image plane can be prompted at the moment, image plane focusing treatment can be considered preferentially during adjustment, the second concave reflecting mirror 4 and the optical sensor 5 are adjusted in the image plane focusing treatment, and proper translation can be carried out without deflection adjustment. Generally speaking, the translational adjustment amount of the second concave mirror 4 is set to be larger, so that the problem that the image plane is out of focus can be solved better by translating the second concave mirror 4.

When the comparison result is: when the spectral resolution of the full-spectrum segment is low and the full-spectrum segment is irregular, namely, the resolutions of all points of the full-spectrum segment are randomly distributed, and the resolutions are high and low and are randomly staggered, but when the whole is low, two possible reasons are generally suggested, namely, the positions of the first concave reflecting mirror 2 are not opposite, the first concave reflecting mirror has the function of collimating polychromatic light incident from the slit 1 into parallel light, if the positions of the first concave reflecting mirror 2 are not opposite (including inclination, ectopy and the like), the collimation effect can be deteriorated, once the collimation effect is deteriorated, the polychromatic light incident to the grating 3 can not meet the conventional grating equation any more, the spectral resolution is deteriorated and can be irregular and can be recycled, at the moment, the first concave reflecting mirror 2 needs to be adjusted in a heavy mode, and even the component needs to be installed again in a severe case. A second possible reason is that the grating 3 is not positioned correctly and the grating 3 is generally aligned 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 image plane, the resolution at both ends of the spectrum range is low, and the resolution at the rotation point is normal, so that corresponding adjustment such as rotating the image plane is required during adjustment. Therefore, the adjustment of the spectrometer can be guided by the evaluation method of the resolution of the full-spectrum spectrometer.

When the frequency of the first parallel light meets the resonance condition of the Fabry-Perot interferometer 8, the frequency spectrum of the second parallel light transmitted by the Fabry-Perot interferometer can have a very high peak value, so that the very high peak value appears in the first spectral data of the converged light, the sensitivity to fine changes emitted by the preset light source 6 can be improved, and the designed free spectral range FSR of the Fabry-Perot interferometer 8 is smaller than the theoretical spectral resolution of the spectrometer to be adjusted.

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

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean 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 invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer 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, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. The adjusting system of the spectrometer is characterized by comprising a chip, a preset light source, a first optical mirror system, a Fabry-Perot interferometer and a second optical mirror system, wherein the preset light source, the first optical mirror system, the Fabry-Perot interferometer and the second optical mirror system are sequentially arranged, and 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. A spectrometer fitting system according to claim 1 or 2, wherein the second optical lens system is a second convex lens.

4. A spectrometer fitting system according to claim 1 or 2, wherein the predetermined light source is a tungsten halogen lamp.