Infrared reflection spectrum testing device based on confocal curved mirror design

Abstract

The invention relates to an infrared reflection spectrum measuring device which is adaptive to a commercial Fourier transform infrared spectrometer and is based on materials (including solids, powder, coatings and liquid phase in-situ reaction) of a confocal off-axis ellipsoidal reflector and an off-axis parabolic reflector. The device mainly comprises a sample cell, two plane mirrors, two off-axis parabolic mirrors and an off-axis ellipsoidal mirror, wherein the two off-axis parabolic mirrors and the off-axis ellipsoidal mirror are arranged in a confocal manner. Positioning and fine adjustment are achieved through the precise sliding rail and the spiral fine adjustment device. Compared with an existing butterfly-shaped light path infrared diffuse reflection accessory, through the coplanar design of the optical axis of each reflector and the detection light beam of the infrared spectrometer, the size of the device is effectively reduced, and the device is adaptive to all commercial infrared spectrometer types. And through the confocal design of the off-axis ellipsoidal reflector and the parabolic reflector, the integral collection angle and intensity of diffuse reflection light of the sample are expanded, and the accuracy of emissivity testing by a reflectometer optical method is improved.

Description

Technical Field

[0001] The invention belongs to an infrared reflection spectrum testing device, and more specifically to a material infrared reflection (or emission) spectrum testing device adapted to a commercial Fourier transform infrared spectrometer and based on a confocal off-axis ellipsoidal mirror and an off-axis parabolic mirror. Background Art

[0002] Emissivity is the ratio of the radiation emittance of an object to the radiation emittance of an absolute black body under the same temperature and wavelength conditions. It characterizes the thermal radiation capacity of an actual object and is an important factor that affects the temperature of an object through radiation heat exchange. With the demand for scientific and technological progress and the improvement of energy conservation and emission reduction targets, thermal management materials play an increasingly important role in many fields such as infrared camouflage, infrared stealth, infrared heat exchange, and radiation refrigeration. In addition to the single emissivity value obtained by traditional material calorimetry testing, researchers are more eager to obtain the emissivity spectrum of the material at the corresponding wavelength, so that the modification research of the material is more targeted and is also conducive to the evaluation of the actual application performance of the material. Therefore, the use of reflectometer optical methods to test the emission spectrum of materials has gradually become an indispensable choice: the substitute test sample is placed in the sample pool, and the infrared reflectivity spectrum of the sample is tested by Fourier infrared spectrometer. According to Kirchhoff's law of thermodynamics, for opaque materials, the spectral emissivity ε(λ) of the material and the reflectivity R(λ) at the same wave number have the following relationship: ε(λ)=1-R(λ), so the emissivity spectrum of the material in the infrared band can be obtained through the relative intensity information of the infrared reflection spectrum.

[0003] Compared with the transmission spectrum, the reflection test mode of the Fourier infrared spectrometer collects the reflected light and part of the scattered light of the sample, and the signal is relatively weak. Therefore, when using the infrared diffuse reflection spectrum as a means to detect the sample emissivity, attention should be paid to reducing the loss of the diffuse reflection light signal in the optical path propagation. The common commercial Fourier infrared spectrometer diffuse reflection accessories generally adopt a "butterfly optical path" in the optical path design: the design of plane reflector-plane reflector-off-axis ellipsoidal reflector-sample cell-off-axis ellipsoidal reflector-plane reflector-plane reflector is a symmetrical design for infrared spectrometers with different light source directions. For the reflectometer optical method to test the emission spectrum of materials, there are several shortcomings in the current commercial devices: 1. The incident light is illuminated into the sample surface through a plane reflector-ellipsoidal reflector. Most of the parallel light cannot be focused on the sample by the ellipsoidal reflector due to the non-ellipsoidal focus. The incident light of the spectrometer cannot be fully utilized, which reduces the intensity of the light signal. 2. To ensure the compatibility of the optical paths of different types of spectrometers, two symmetrical ellipsoidal reflectors are used in common commercial solutions. The diffusely reflected infrared light of the sample may return through the incident optical path and produce coherent decomposition with the incident light of the spectrometer, which will interfere with the test results. 3. The mirror profile of the off-axis ellipsoidal reflector is connected to the center of the sample pool at a 120° cone angle, which is only the minimum value required for the test, and it is only installed on one side of the sample pool. The collection effect of the diffusely reflected infrared light emitted by the sample is very limited, and the emission spectrum obtained by the final test has a large deviation from the true value. 4. In the process of multiple reflections of the sample reflected light into the spectrometer signal collection device through the ellipsoidal reflector-plane reflector-plane reflector, the diffusely reflected infrared scattering angle containing the sample information continues to increase, and the proportion of infrared light that can finally reach the signal collection point is further reduced. That is, the optical signal loss is large in the process of reaching the signal collection device after multiple reflections, and the infrared reflection signal is usually weaker than the transmission signal, and the collection angle and orientation are limited. Several factors are not conducive to the accurate determination of the optical properties of the sample such as the emissivity spectrum through infrared reflection spectroscopy. Summary of the invention

[0004] In view of this, in order to solve the problem of large collection loss of diffuse reflection light signals in traditional infrared diffuse reflection accessories, the present invention provides an infrared reflection spectrum testing device based on a confocal curved mirror design.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A device for measuring infrared emission spectra of materials (including solids, powders, coatings and liquid phase in-situ reactions) using a commercial Fourier transform infrared spectrometer, based on a confocal off-axis ellipsoidal reflector and an off-axis parabolic reflector. The present invention is composed of a plane reflector, an off-axis parabolic reflector, an off-axis ellipsoidal reflector and a sample pool, and is positioned and fixed by a precision slide rail and a spiral fine-tuner. There are two plane reflectors and two off-axis parabolic reflectors, and one off-axis ellipsoidal reflector (depending on the processing capacity, it can also be made of two pieces spliced ​​together). The optical axis of each reflector is coplanar with the detection beam of the Fourier transform infrared spectrometer, so as to reduce the size of the device and make it compatible with all commercial Fourier transform infrared spectrometer models;

[0007] The optical axis of each reflector is coplanar with the detection beam of the Fourier transform infrared spectrometer, so as to reduce the size of the device and make it suitable for all commercial models of Fourier transform infrared spectrometers;

[0008] The two plane reflectors are divided into a first plane reflector and a second plane reflector, and the two off-axis parabolic reflectors are divided into a first off-axis parabolic reflector and a second off-axis parabolic reflector;

[0009] After the detection light is emitted from the light outlet of the infrared spectrometer, it passes through the first plane reflector, the first off-axis parabolic reflector, the sample cell, the off-axis ellipsoidal reflector, the second off-axis parabolic reflector, the second plane reflector in sequence, and finally enters the light outlet hole, and the infrared test data is collected by the spectrometer.

[0010] In the present invention, the parallel detection light beam emitted from the light outlet of the spectrometer is reflected by the first plane reflector to the first off-axis parabolic reflector, and the first off-axis parabolic reflector converges the parallel detection light off-axis to the confocal point between the first off-axis parabolic reflector and the off-axis ellipsoidal reflector, that is, the position of the sample cell, which is recorded as F1;

[0011] The detection light reflected by the diffuse reflection (or specular reflection) sample in the sample pool is integrated and reflected by the off-axis ellipsoidal reflector and converged to the second focus of the off-axis ellipsoidal reflector, which is recorded as F2;

[0012] It is then converted into parallel light by a second off-axis parabolic reflector that is confocal (F2) with the off-axis ellipsoidal reflector, reflected by a second plane reflector into the light exit hole of the spectrometer, and the spectrometer collects data to measure the infrared emission spectrum of the material.

[0013] The F1 and F2 are two focal positions of the off-axis ellipsoidal reflector respectively. The position point F1 is the common focal point of the off-axis ellipsoidal reflector and the first off-axis parabolic reflector; the position point F2 is the common focal point of the off-axis ellipsoidal reflector and the second off-axis parabolic reflector.

[0014] Preferably, the infrared reflection spectrum testing device based on the confocal curved mirror design has an infrared optical path design that includes a total of five infrared high-reflection lenses, which reduces the number of lenses and reduces the loss of optical signals in the propagation path.

[0015] Preferably, the off-axis ellipsoidal reflector has a monomeric or spliced ​​structure, and its maximum forward collection angle is 180°, the maximum backward collection angle is 145°, the maximum bilateral lateral collection angle is 180°, and the overall shape is basically equivalent to three-eighths of a complete ellipsoidal surface reflector.

[0016] Preferably, the off-axis ellipsoidal reflector is fixed in position, and a circular light hole with a diameter of 10 mm is opened in the direction of the line connecting the first focus F1 and the first off-axis parabolic reflector to facilitate the detection of incident light;

[0017] Preferably, the line connecting the center of the first off-axis parabolic reflector and the position F1 is at an angle of 45° to the horizontal plane, so as to ensure that the incident light beam on the sample surface is within the range of 35-45° to obtain the strongest infrared light reflection signal;

[0018] Preferably, the reflection angles of the first plane reflector and the second plane reflector can be fine-tuned to ensure a smooth optical path and maximize signal strength;

[0019] Preferably, the position and reflection angle of the first off-axis parabolic reflector can be fine-tuned to facilitate adjusting the size of the incident light spot for samples of different properties and sizes;

[0020] Preferably, the position and reflection angle of the second off-axis parabolic reflector can be fine-tuned to facilitate the adjustment of the outgoing light beam so as to obtain the maximum signal strength;

[0021] Preferably, the carrier of the sample pool can be flexibly designed according to the properties and size of the sample, with a minimum diameter of 2 mm (or 2×2 mm 2 ), maximum diameter 10mm (or 10×10mm 2 ), the sample surface can be fine-tuned within a maximum range of 10° horizontally and tilted toward the incident beam to meet test needs.

[0022] Preferably, the size and shape of the sample pool can be changed according to different usage requirements such as powder / sheet / block testing, in-situ reaction, variable temperature testing, etc., and the available space dimensions include: height 70mm, length 50mm, and width 50mm.

[0023] Preferably, the sample pool has a precision slide rail positioning structure to facilitate the placement and positioning of samples and other auxiliary devices (such as a constant temperature and variable temperature testing mechanism);

[0024] The precision slide rail positioning structure includes a sample pool placement platform and a precision slide rail; the sample pool is connected to the precision slide rail via the sample pool placement platform;

[0025] Precision slide rails are fixed to the bottom of the device housing.

[0026] Preferably, the device is provided with a retractable light-shielding cylinder on the side wall of the housing, which can be adjusted according to different spectrometer signals to avoid external light interfering with the test.

[0027] Preferably, an angle regulator capable of controlling the angle of the sample pool is installed below the sample pool.

[0028] The positioning pins can be used to flexibly design and adjust the device base plate according to different matching spectrometers, and can be used with most models of Fourier infrared spectrometers.

[0029] Preferably, the reflective film is a gold film with high infrared reflectivity, which can reduce the loss of infrared light in the optical path propagation. Other optional infrared high reflective coating materials include aluminum and silver (protective layer is required).

[0030] Preferably, the accessory size information includes: height of 140 mm, length of 140 mm, width of 100 mm, and can be placed in most Fourier infrared spectrometers.

[0031] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0032] In the design of traditional infrared diffuse reflection accessories, a combination of plane reflector-plane reflector-ellipsoid reflector-sample cell-plane reflector-plane reflector is mostly used, while the present invention adopts a combination of plane reflector-off-axis parabolic reflector-sample cell-off-axis ellipsoid reflector-off-axis parabolic reflector-plane reflector, which reduces the number of lenses and reduces the loss of infrared light signals caused by mirror reflection; expands the collection angle of infrared light reflected by the sample, with a maximum forward collection angle of 180°, a maximum backward collection angle of 145°, and a maximum double lateral collection angle of 180°, which has a greater degree of accuracy in the collection process of sample optical information. The infrared light beam is incident on the sample surface at an angle of 35 to 45 degrees, which is the range for obtaining the strongest sample infrared light reflection spectrum signal; the scope of the accessories for test objects has been expanded, and the infrared spectrum information of diffuse reflection, quasi-mirror reflection, and mirror reflection samples can be collected; the combination of the confocal off-axis ellipsoidal reflector and the off-axis parabolic reflector solves the problem that the plane reflector further deviates from the convergent infrared light reflected by the ellipsoidal reflector, resulting in a small proportion of infrared light reaching the infrared spectrometer signal collection device after diffuse reflection of the sample, incomplete spectral information collection, and a large deviation between the emission spectrum and the true value.

[0033] Compared with traditional infrared diffuse reflectance accessories, the present invention can collect infrared spectral information in a larger range, improve the accuracy of emissivity testing using reflectometer optical methods, and at the same time control the design size of the overall device. It can be used in most Fourier infrared spectrometers, especially for testing samples with weak infrared reflection signals and for observing the optical properties of emission, reflection, and absorption of samples at corresponding wave numbers in a wide infrared band through infrared spectroscopy. It is convenient for researchers to study the infrared radiation characteristics of samples through inverse design optical methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0035] Figure 1 is a side view schematic diagram of the infrared reflection device of the present invention;

[0036] Figure 2 This is a schematic diagram of the installation of the infrared reflection device of the present invention in conjunction with a Fourier infrared spectrometer;

[0037] Figure 3 It is a schematic diagram of the optical path design of the infrared reflection device of the present invention;

[0038] Among them, in the figure:

[0039] 1-first plane reflector; 2-first off-axis parabolic reflector; 3-sample pool; 4-off-axis ellipsoidal reflector; 5-second off-axis parabolic reflector; 6-second plane reflector; 7-sample pool placement platform; 8-precision slide rail; 9-retractable light shielding tube; 10-angle regulator. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Example 1

[0042] This embodiment provides an infrared reflection spectrum test device based on a confocal curved mirror design. The infrared reflection test accessory is designed based on the Fourier infrared spectrometer FITR-650S. Under the condition that the size of the infrared spectrometer sample bin is met, it can theoretically be used with most types of infrared spectrometers.

[0043] The device of the present invention comprises: a plane reflector, an off-axis parabolic reflector, an off-axis ellipsoidal reflector, and a sample pool, wherein the plane reflector and the off-axis parabolic reflector are each provided with two pieces, and the off-axis ellipsoidal reflector is provided with one piece, and all of them are placed on a vertical plane passing through a line connecting a light exit hole and a light entrance hole of a spectrometer;

[0044] The plane reflector includes a first plane reflector 1 and a second plane reflector 6, the off-axis parabolic reflector includes a first off-axis parabolic reflector 2 and a second off-axis parabolic reflector 5, the off-axis ellipsoidal reflector is an off-axis ellipsoidal reflector 4, and the sample pool is a sample pool 3;

[0045] The first plane reflector 1 reflects the parallel detection light beam emitted from the light outlet of the spectrometer to the first off-axis parabolic reflector 2. The size of the mirror should be larger than the infrared light source, and the installation position should completely reflect the infrared light emitted by the infrared light source to the first off-axis parabolic reflector 2.

[0046] The first off-axis parabolic reflector 2 converges the parallel detection light off-axis to the common focus between it and the off-axis ellipsoidal reflector, i.e., the center F1 of the sample pool 3. The off-axis angle of the first off-axis parabolic reflector 2 can be designed according to the sample chamber space of the infrared spectrometer, and the mirror size should fully receive the infrared light reflected by the plane reflector 1.

[0047] The detection light reflected by the diffusely reflected (or specularly reflected) sample in the sample pool 3 is integrated and reflected by the off-axis ellipsoidal reflector 4 and converged to the position of the second focus F2 of the off-axis ellipsoidal reflector 4;

[0048] The light is then converted into parallel light by a second off-axis parabolic reflector 5 having the same focal point (F2) as the off-axis ellipsoidal reflector 4, and is reflected by a second plane reflector 6 into the light exit hole of the spectrometer. The spectrometer collects data to measure the infrared emission spectrum of the material.

[0049] The point F1 is both the ellipsoid major axis focus 1 of the off-axis ellipsoid reflector 4 and the parabola focus of the first off-axis parabolic reflector 2 , and the point F2 is both the ellipsoid major axis focus 2 of the off-axis ellipsoid reflector 4 and the parabola focus of the second off-axis parabolic reflector 5 .

[0050] The line connecting the center of the first off-axis parabolic reflector 2 and the position F1 is at an angle of 45° to the horizontal plane to ensure that the incident light beam on the sample surface is within the range of 35 to 45° to obtain the strongest infrared light reflection signal.

[0051] The off-axis ellipsoidal reflector 4 is fixed in position, and a circular aperture with a diameter of 10 mm is opened in the direction of the line connecting the first focus F1 and the first off-axis parabolic reflector to facilitate the detection of incident light;

[0052] The position and reflection angle of the first off-axis parabolic reflector 2 can be fine-tuned to facilitate adjusting the size of the incident light spot for samples of different properties and sizes;

[0053] The position and reflection angle of the second off-axis parabolic reflector 5 can be fine-tuned to facilitate the adjustment of the outgoing light beam so as to obtain the maximum signal strength;

[0054] The off-axis ellipsoidal reflector 4 is a single body or spliced ​​structure, and its maximum forward collection angle is 180°, the maximum backward collection angle is 145°, and the maximum bilateral side collection angle is 180°. The overall shape is basically equivalent to a three-eighths ellipsoidal reflector.

[0055] The base layers of the plane reflector, off-axis parabolic reflector and off-axis ellipsoidal reflector are all made of 6061 aluminum, and the reflective films are all infrared high-reflectivity gold films.

[0056] The size and shape of the sample pool 3 can be replaced according to different usage requirements such as powder / sheet / block testing, in-situ reaction, variable temperature testing, etc. The available space dimensions include: height 70mm, length 50mm, and width 50mm.

[0057] In this embodiment, the sample pool is provided with a precision slide rail positioning structure to facilitate the placement and positioning of samples and other auxiliary devices (such as a constant temperature and variable temperature testing mechanism).

[0058] The precision slide rail positioning structure includes a sample pool placement platform 7 and a precision slide rail 8; the sample pool 3 is connected to the precision slide rail 8 via the sample pool placement platform 7;

[0059] The precision slide rail 8 is fixed to the bottom of the device housing, and a retractable light-shielding cylinder 9 is installed on the side wall of the housing, which can be adjusted according to different spectrometer signals to avoid external light interfering with the test.

[0060] An angle regulator 10 for controlling the angle of the sample pool is installed below the sample pool.

[0061] The positioning pins can be used to flexibly design and adjust the device base plate according to different matching spectrometers, and can be used with most models of Fourier infrared spectrometers.

[0062] The accessory size information includes: height 140mm, length 140mm, width 100mm.

[0063] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0064] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An infrared reflection spectrum testing device based on a confocal curved mirror design, characterized in that: The device comprises: 2 plane reflectors, 2 off-axis parabolic reflectors, 1 off-axis ellipsoidal reflector, and a sample pool; The optical axes of the plane reflector, the off-axis parabolic reflector and the off-axis ellipsoidal reflector are designed to be coplanar with the detection beam of the spectrometer, and the plane is in a vertical state; The two plane reflectors are divided into a first plane reflector and a second plane reflector, and the two off-axis parabolic reflectors are divided into a first off-axis parabolic reflector and a second off-axis parabolic reflector; After the detection light is emitted from the light outlet of the infrared spectrometer, it passes through the first plane reflector, the first off-axis parabolic reflector, the sample cell, the off-axis ellipsoidal reflector, the second off-axis parabolic reflector, the second plane reflector in sequence, and finally enters the light outlet hole, and the infrared test data is collected by the spectrometer.

2. The infrared reflection spectrum testing device based on the confocal curved mirror design according to claim 1 is characterized in that: The parallel detection light beam emitted from the light outlet of the spectrometer is reflected by the first plane reflector to the first off-axis parabolic reflector, and the first off-axis parabolic reflector converges the parallel detection light off-axis to the confocal point between the first off-axis parabolic reflector and the off-axis ellipsoidal reflector, that is, the position of the sample cell, which is recorded as F1; The detection light reflected by the diffuse reflection or specular reflection sample in the sample pool is integrated and reflected by the off-axis ellipsoidal reflector and converged to the second focus of the off-axis ellipsoidal reflector, which is recorded as F2; The light is then converted into parallel light by a second off-axis parabolic reflector that shares the same focal point F2 with the off-axis ellipsoidal reflector, and is reflected by a second plane reflector into the light exit hole of the spectrometer. The spectrometer collects data to measure the infrared emission spectrum of the material. The F1 and F2 are two focal positions of the off-axis ellipsoidal reflector respectively.

3. The infrared reflection spectrum testing device based on the confocal curved mirror design according to claim 2 is characterized in that: The off-axis ellipsoidal reflector is fixed in position, and a circular aperture with a diameter of 10 mm is opened in the direction of the line connecting the first focus F1 and the first off-axis parabolic reflector to facilitate the detection of incident light; The reflection angles of the first plane reflector and the second plane reflector can be fine-tuned to ensure a smooth optical path and maximize signal strength; The position and reflection angle of the first off-axis parabolic reflector can be fine-tuned to facilitate adjusting the size of the incident light spot for samples of different properties and sizes; The position and reflection angle of the second off-axis parabolic reflector can be fine-tuned to facilitate the adjustment of the outgoing light beam so as to obtain the maximum signal strength; The sample pool carrier is flexibly designed according to the properties and size of the sample, with a minimum diameter of 2mm or 2×2mm 2 , maximum diameter 10mm or 10×10mm 2 The sample surface can be fine-tuned in the horizontal direction and in the tilt range of up to 10° toward the incident beam direction to meet the test needs.

4. The infrared reflection spectrum testing device based on the confocal curved mirror design according to claim 2 is characterized in that: Position point F1 is the common focus of the off-axis ellipsoidal reflector and the first off-axis parabolic reflector; Position point F2 is the common focus of the off-axis ellipsoidal reflector and the second off-axis parabolic reflector.

5. The infrared reflection spectrum testing device based on the confocal curved mirror design according to claim 2 is characterized in that: The off-axis ellipsoidal reflector has a structure of a single body or a spliced ​​structure, and its maximum forward collection angle is 180°, the maximum backward collection angle is 145°, and the maximum bilateral side collection angle is 180°. The overall shape is basically equivalent to a three-eighths ellipsoidal reflector; The line connecting the center of the first off-axis parabolic reflector and the position point F1 is at an angle of 45° to the horizontal plane to ensure that the incident light beam on the sample surface is within the range of 35 to 45° to obtain the strongest infrared light reflection signal.

6. The infrared reflection spectrum testing device based on the confocal curved mirror design according to claim 1 is characterized in that: A precision slide rail positioning structure is provided at the bottom of the sample pool; The precision slide rail positioning structure comprises a sample pool taking and placing platform and a precision slide rail; the sample pool is connected to the precision slide rail via the sample pool taking and placing platform.

7. The infrared reflection spectrum testing device based on the confocal curved mirror design according to claim 1 is characterized in that: The plane reflector, the off-axis parabolic reflector and the off-axis ellipsoidal reflector all include a substrate layer and an infrared high-reflection gold-plated film on the surface.

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