Calibration method for multi-optical-path weak absorption instrument

Abstract

The invention relates to a multi-optical-path weak absorption instrument calibration method. Comprising the steps of height setting, light driving position point control, shielding adjustment operation and four-stage debugging operation, and has the advantages that the structure is simple, the effectiveness and reliability of multi-optical-path focus positions are ensured, the acquisition effect is good, and the precision is high. In addition, the invention further provides a multi-light-path weak absorption instrument which comprises a pump light emitter, a detection light emitter, a first focusing lens, a three-dimensional XYZ-axis stepping motor, a power meter, a second focusing lens, a first silver-plated reflector, a second silver-plated reflector, a third focusing lens, a gold-plated hemisphere and a detector. Therefore, uncertain factors of the focus of the pump light, the coincidence position of the two laser detection light beams and the size of the light spots are accurately judged, the size of the pump light focusing light spots and the position of the light spots can be more accurately judged, and the calibration method, namely the calibration device for the multi-light-path weak absorption instrument, of the multi-light-path weak absorption instrument is higher in precision when being applied to calculation of the absorption coefficient of a sample. And data is more reliable.

Description

Technical Field

[0001] The invention relates to the technical field of photoelectric product measurement, and in particular to a calibration method for a multi-light path weak absorption instrument. Background Art

[0002] The existing technology uses the color card to calibrate the focus position when calibrating the multi-path weak absorption instrument. When the focus of the pump light and the detection light is uncertain, the detection light needs to be blocked to test the focal length position of the pump light. When the color card is used to measure the focus position of the pump light, it is necessary to use the naked eye to judge the position of the smallest spot. There is uncertainty in the focus position and large instability errors. After the focus position of the pump light is initially found, the focusing lens is moved back and forth according to the focal length of the focusing lens on the detection light path so that the focus position hits the focus position of the pump light. The above method has the problems of pump light focus instability, detection light focus uncertainty and other factors interfering with the photothermal deflection signal. The photothermal deflection signal is not strong enough, which will lead to large errors in the test results, large noise influence, low sensitivity and other problems.

[0003] To this end, the present invention provides a multi-path weak absorption instrument calibration method to solve the focus uncertainty factor, the overlap position of two laser beams and the accurate judgment of the spot size during use. Summary of the invention

[0004] (1) Technical issues to be solved

[0005] The object of the present invention is to provide a multi-path weak absorption instrument calibration method;

[0006] Another object of the present invention is to provide a multi-light path weak absorption instrument;

[0007] Another object of the present invention is to provide an application of the above-mentioned multi-path weak absorption instrument calibration method in calculating the absorption coefficient of a sample;

[0008] Another object of the present invention is to provide an application of the above-mentioned multi-path weak absorption instrument in calculating the absorption coefficient of a sample.

[0009] The present invention adopts a beam analyzer in the process of calibrating a multi-path weak absorption instrument, which can more accurately determine the size and position of the focused spot of the pump light, and can better observe through an external computer terminal, so that the pump light and the detection light can be better overlapped, and the intensity of the photothermal deflection signal can be effectively improved, so that the test results are accurate, reliable, and repeatable and stable.

[0010] (2) Technical solution

[0011] In order to solve the above technical problems, the first aspect of the present invention provides:

[0012] A multi-path weak absorption instrument calibration method comprises the following steps:

[0013] 1. Set the height: fix the center height of the pump light and the detection light, and keep the centers of all lenses at this height and on the same optical axis. The lenses include three focusing lenses with different focal lengths, the first silver-coated reflector and the second silver-coated reflector.

[0014] 2. Control the light injection position: the pump light passes through the first focusing lens and hits the power meter. The detection light passes through the second focusing lens and is reflected by the first silver-coated reflector and the second silver-coated reflector, and then passes through the third focusing lens and hits the gold-coated hemisphere. After being reflected by the gold-coated hemisphere, the final focus hits the detector.

[0015] 3. Blocking adjustment operation: A three-dimensional XYZ-axis stepper motor is arranged at the position where the first focusing lens transmits the light beam backwards, and a beam analyzer is installed on the three-dimensional XYZ-axis stepper motor. During the operation, the optical path of the detection light will pass through the first silver-plated reflector to the second silver-plated reflector. The three-dimensional XYZ-axis stepper motor is also arranged between the first silver-plated reflector and the second silver-plated reflector.

[0016] 4. Debugging operation:

[0017] The first stage: block the detection light. At this time, the pump light is in a normal emission state. Use the beam analyzer on the three-dimensional XYZ axis stepper motor to move along the Z axis at the position where the pump light is focused. Then use the beam analyzer software on the computer to check the spot size, mark the place where the spot is smallest and record the current coordinate position of the three-dimensional XYZ axis stepper motor.

[0018] The second stage: block the pump light and turn on the detection light. Set the beam analyzer position to remain unchanged or at the pump light focus position in the first stage. Move the second focusing lens at the rear end of the detection light beam emission back and forth. By adjusting the position of the second focusing lens, let the focus continue to hit the beam analyzer. Finally, make the focus position of the detection light the same as the Z-axis position of the pump light focus.

[0019] Stage 3: When the focal position of the detection light is the same as the focal position of the pump light in the Z-axis direction, fix the position of the second focusing lens, rotate the first silver-coated reflector to make the focal point of the detection light coincide with the focal point of the pump light in the Y-axis direction, and then the detection light hits the center of the third focusing lens after passing through the second silver-coated reflector;

[0020] Stage 4: The light beam emitted from the center of the third focusing lens hits the gold-coated hemisphere. The distance between the gold-coated hemisphere and the detector is adjusted so that the focused light spot hits the detector.

[0021] Furthermore, the wavelength of the pump light is 1064 nm, and the detection light is the light emitted by a 633 nm HE-NE laser.

[0022] Furthermore, the first focusing lens is a F=75 mm focusing lens, the second focusing lens is a 150 mm focusing lens, and the third focusing lens is a F=50 mm focusing lens.

[0023] Furthermore, during calibration, a beam analyzer is used to detect the focus of the pump light and the probe light to ensure that the focus of the two beams is at the same position.

[0024] Furthermore, the signal receiving platform is composed of a second silver-plated reflector, a third focusing lens, a gold-plated hemisphere, and a detector.

[0025] Furthermore, the distance from the first silver-coated reflector to the second silver-coated reflector is 220 mm.

[0026] The second aspect of the present invention provides:

[0027] A multi-path weak absorption instrument, wherein the multi-path weak absorption instrument is calibrated by the multi-path weak absorption instrument calibration method.

[0028] Furthermore, the multi-path weak absorption instrument comprises a pump light emitter and a detection light emitter, a first focusing lens, a three-dimensional XYZ-axis stepping motor and a power meter are arranged in the direction of the pump light beam emission of the pump light emitter, and a beam analyzer is mounted on the three-dimensional XYZ-axis stepping motor;

[0029] A second focusing lens and a first silver-plated reflector are arranged in the direction of the detection light beam emission of the detection light emitter. When in use, the focus of the detection light is overlapped with the focus of the pump light through the second focusing lens and the first silver-plated reflector; a second silver-plated reflector, a third focusing lens and a gold-plated hemisphere are also arranged behind the detection light path, and the three-dimensional XYZ-axis stepping motor and the beam analyzer are arranged between the first silver-plated reflector and the second silver-plated reflector, and the focused light spot is projected onto the detector through reflection of the gold-plated hemisphere.

[0030] Furthermore, the first focusing lens, the second focusing lens, the first silver-plated reflecting mirror, the second silver-plated reflecting mirror, the third focusing lens and the gold-plated hemisphere are arranged at the same height.

[0031] Furthermore, the multi-path weak absorption instrument is electrically connected to a computer terminal for checking the light spot size.

[0032] Furthermore, when using a beam analyzer to detect the focus of the pump light and the probe light, it is necessary to ensure that the focus of the two beams is at the same position.

[0033] The third aspect of the present invention provides:

[0034] The application of the above multi-path weak absorption instrument calibration method in calculating the absorption coefficient of the sample.

[0035] A fourth aspect of the present invention provides:

[0036] The application of the above multi-path weak absorption instrument in calculating the absorption coefficient of the sample.

[0037] (3) Beneficial effects

[0038] The beneficial effects of the present invention are as follows: the present invention overcomes the problems existing in the prior art, such as the instability of the focus of the pump light, the uncertainty of the focus of the detection light, etc., which interfere with the photothermal deflection signal, and the photothermal deflection signal is not strong enough, which will lead to large errors in the test results, large noise influence, low sensitivity, etc. The present invention adopts a beam analyzer in the process of calibrating the multi-path weak absorption instrument, solves the uncertainty of the focus of the pump light, the overlap position of the two laser detection lights, and the accurate judgment of the spot size, can more accurately judge the size and position of the pump light focus spot, and can better observe through the external computer terminal, can better overlap the pump light and the detection light, effectively improve the intensity of the photothermal deflection signal, make the test results accurate and reliable, and the repeatability is stable, and then the detection light is distorted when passing through the refractive index gradient area of ​​the sample, and the sample absorption coefficient is better calculated by measuring the distortion degree of the detection light, and the absorption of the sample is obtained. The present invention has a simple structure, ensures the effectiveness of the multi-path focus position, has a good collection effect, high precision and strong reliability, and is worthy of popularization and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The figure is a schematic diagram of the three-dimensional structure of a multi-light path weak absorption instrument of the present invention.

[0040] Figure 2 The figure is a schematic diagram of the top view of the structure of a multi-light path weak absorption instrument of the present invention.

[0041] Figure 3 In the present invention, a computer terminal displays a view of the separation of the pump light and the detection light.

[0042] Figure 4 In the present invention, a computer terminal displays a view of the overlap of the pump light and the detection light.

[0043] Figure 5 In the present invention, the two beams overlap to block the 633nm detection light, leaving only the 1064nm pump light.

[0044] Figure 6In the present invention, two beams overlap to block the 1064nm pump light, leaving only the 633nm detection light. In the figure: 1 pump light emitter, 2 first focusing lens, 3 detection light emitter, 4 second focusing lens, 5 first silver-coated reflector, 6 beam analyzer, 7 three-dimensional XYZ axis stepper motor, 8 power meter, 9 second silver-coated reflector, 10 third focusing lens, 11 gold-coated hemisphere, 12 detector. DETAILED DESCRIPTION

[0045] The present invention can be better understood according to the following examples. However, it is easy for those skilled in the art to understand that the specific material ratios, process conditions and results described in the examples are only used to illustrate the present invention, and should not and will not limit the present invention described in detail in the claims.

[0046] Unless otherwise specified, the experimental materials and reagents used are consumables and reagents that can be obtained from conventional commercial channels.

[0047] Embodiment 1:

[0048] A multi-path weak absorption instrument calibration method: using the beam analyzer measurement method, according to the attached Figure 1 The placement points of each part are preset in a manner, and a beam analyzer 6 is assembled on a three-dimensional XYZ axis stepper motor 7, that is, the calibration method includes a pump light source, a detection light source, a sample stage and a signal receiving platform, and a beam analyzer is arranged at the focus of the pump light and the detection light;

[0049] At this time, the sample stage is installed on the X-axis motor, and a beam analyzer 6 is placed on the sample stage; the second silver-coated reflector 9, the third focusing lens 10, the gold-coated hemisphere 11, and the detector 12 constitute a signal receiving platform; the distance from the first silver-coated reflector 5 to the second silver-coated reflector 9 is set to 220 mm;

[0050] It should be noted that the X-axis direction here is set as the vertical direction in space, and the Z-axis direction is set as the vertical direction in space. Figure 2 The left and right directions are the directions from which the pump light is emitted; the Y-axis direction is the direction from which the pump light is emitted. Figure 2 In the up-down direction, that is, the direction in which the detection light is emitted, the X-axis in this device adopts a fixed height and is not adjusted, because the position of the X-axis has been determined in the process of adjusting the light path, so the operation of the X-axis is not described in this scheme;

[0051] Then turn on the pump light, block the detection light, and use the beam analyzer 6 to move along the Z-axis direction at the position where the pump light is focused. Figure 2 Move horizontally in the computer to check the spot size, mark the place where the spot is smallest and write down the coordinate position of the current three-dimensional XYZ axis stepper motor;

[0052] Block the pump light, turn on the detection light, move the second focusing lens 4 of F=150mm back and forth to make the focus hit the beam analyzer 6. At this time, the position of the beam analyzer 6 remains unchanged and is still at the focus position of the pump light. Make the focus position of the detection light the same as the Z-axis position of the pump light focus. Fix the second focusing lens 4 of F=150mm, rotate the first silver-coated reflector 5 to make the focus of the detection light coincide with the focus of the pump light in the Y-axis direction. After passing through the second silver-coated reflector 9, the detection light hits the center of the third focusing lens 10 of F=50mm. Adjust the distance between the gold-coated hemisphere 11 and the detector 12 so that the focused light spot hits the detector 12.

[0053] It should be noted here that in the field of optics, the gold-plated hemisphere 11 generally refers to an optical element in the shape of a hemisphere, the surface of which is plated with a layer of gold. This special treatment can improve the hemisphere's ability to reflect light, especially in the infrared band. The gold-plated hemisphere 11 is often used in the fields of optical measurement, laser systems, infrared imaging and spectroscopy, because the high reflectivity of gold can provide more accurate measurement results and clearer image quality;

[0054] In the above process, according to the photothermal deflection technology, the center height is fixed and the centers of all lenses are kept on the same optical axis at this height, so that the 1064nm detection light passes through the F=75mm first focusing lens 2 and hits the power meter 8, and the 633nm HE-NE detection light passes through the F=150mm second focusing lens 4 and is reflected by two silver-plated reflectors through the F=50mm third focusing lens 10 and hits the gold-plated hemisphere 11, and is reflected by the gold-plated hemisphere 11 and finally hits the detector 12;

[0055] When the above operations are completed, the calibration effect of the multi-path weak absorption instrument is achieved.

[0056] Embodiment 2:

[0057] A multi-path weak absorption instrument, comprising a pump light emitter 1 and a detection light emitter 3, wherein the pump light emitter 1 emits a 1064nm pump light beam, the detection light emitter 3 is a 633nm HE-NE laser, and the detection light beam is emitted by the 633nm HE-NE laser, a first focusing lens 2, a three-dimensional XYZ axis stepping motor 7 and a power meter 8 are arranged in the pump light beam emitting direction of the pump light emitter 1, a beam analyzer 6 is mounted on the three-dimensional XYZ axis stepping motor 7, and the specification of the first focusing lens 2 is an F=75mm focusing lens;

[0058] The detection light emitter 3 is provided with a second focusing lens 4 and a first silver-plated reflector 5 in the direction of the detection light beam emission. The specification of the second focusing lens 4 is a focusing lens of F=150mm. When in use, the focus of the detection light is overlapped with the focus of the pump light through the second focusing lens 4 and the first silver-plated reflector 5. A second silver-plated reflector 9, a third focusing lens 10 and a gold-plated hemisphere 11 are also provided at the rear of the detection light path. The specification of the third focusing lens 10 is a focusing lens of F=50mm. The three-dimensional XYZ axis stepping motor 7 and the beam analyzer 6 are provided. It is placed between the first silver-coated reflector 5 and the second silver-coated reflector 9. During calibration, the beam analyzer 6 is set at the focus of the pump light and the detection light; finally, the focused light spot is hit on the detector 12 through the reflection of the gold-coated hemisphere 11, wherein the first focusing lens 2, the second focusing lens 4, the first silver-coated reflector 5, the second silver-coated reflector 9, the third focusing lens 10 and the gold-coated hemisphere 11 are set at the same height. In order to better observe the light spot situation, the multi-path weak absorption instrument is electrically connected to the computer end for checking the light spot size.

[0059] The multi-light path calibration method proposed by the present invention has a simple structure, ensures the effectiveness and reliability of the multi-light path focus position, and has good collection effect and high precision. It should be noted that the measurement principle of the present invention in the application of calculating the absorption coefficient of the sample adopts the surface thermal lens technology, which utilizes the film distortion caused by the photothermal effect generated by the optical material or film under the irradiation of the detection light intensity, that is, photothermal deformation. A standard detection light beam will produce a coupled diffraction effect after passing through the curved surface. By testing this diffraction effect and inferring the deformation of the film surface, many optical properties (including weak absorption characteristics) of the optical film and material can be obtained. The sample to be tested produces density changes caused by the increase in temperature of the laser working material and thermal deformation of the crystal surface due to the increase in temperature under the action of the pump light; when the laser is working, the heat generated will cause the surface of the crystal or working material to deform, and the detection light will be distorted when passing through the refractive index gradient area of ​​the sample. The absorption of the sample is obtained by measuring the degree of distortion of the detection light.

[0060] Use a beam analyzer to find the positions of the foci of the two beams and record the Z-axis distance. Place the fixture and calculate the error distance between the sample and the Z-axis of the beam analyzer to ensure that the foci of the two laser beams hit the sample.

[0061] In order to fully prove that the present invention is superior to the prior art, Figure 3-6 middle, Figure 5 The center of mass coordinates in this state are (X7010, Y2448), Figure 6The centroid coordinates in the state are (X6959, Y2421). At this time, the centroid coordinates of the focus of the two beams of light differ within 52um, which cannot be done by naked eye judgment using the existing color display card. Therefore, the beam analyzer can determine the overlap of the two beams of light more accurately, conveniently and quickly. The exemplary implementation of the scheme proposed in the present disclosure is described in detail above with reference to the preferred embodiments. However, it can be understood by those skilled in the art that, without departing from the concept of the present disclosure, various modifications and variations can be made to the above-mentioned specific embodiments, and various technical features and structures proposed in the present disclosure can be combined in various ways without exceeding the protection scope of the present disclosure, which is determined by the attached claims.

Claims

1. A multi-path weak absorption instrument calibration method, characterized in that: The following steps are involved:

1. Set the height: fix the center height of the pump light and the detection light, and keep the centers of all lenses at this height and on the same optical axis. The lenses include three focusing lenses with different focal lengths, the first silver-coated reflector and the second silver-coated reflector.

2. Control the light injection position: the pump light passes through the first focusing lens and hits the power meter. The detection light passes through the second focusing lens and is reflected by the first silver-coated reflector and the second silver-coated reflector, and then passes through the third focusing lens and hits the gold-coated hemisphere. After being reflected by the gold-coated hemisphere, the final focus hits the detector.

3. Blocking adjustment operation: A three-dimensional XYZ-axis stepper motor is arranged at the position where the first focusing lens transmits the light beam backwards, and a beam analyzer is installed on the three-dimensional XYZ-axis stepper motor. During the operation, the optical path of the detection light will pass through the first silver-plated reflector to the second silver-plated reflector. The three-dimensional XYZ-axis stepper motor is also arranged between the first silver-plated reflector and the second silver-plated reflector.

4. Debugging operation: The first stage: block the detection light. At this time, the pump light is in a normal emission state. Use the beam analyzer on the three-dimensional XYZ axis stepper motor to move along the Z axis at the position where the pump light is focused. Then use the beam analyzer software on the computer to check the spot size, mark the place where the spot is smallest and record the current coordinate position of the three-dimensional XYZ axis stepper motor. The second stage: block the pump light and turn on the detection light. Set the beam analyzer position to remain unchanged or at the pump light focus position in the first stage. Move the second focusing lens at the rear end of the detection light beam emission back and forth. By adjusting the position of the second focusing lens, let the focus continue to hit the beam analyzer. Finally, make the focus position of the detection light the same as the Z-axis position of the pump light focus. Stage 3: When the focal position of the detection light is the same as the focal position of the pump light in the Z-axis direction, fix the position of the second focusing lens, rotate the first silver-coated reflector to make the focal point of the detection light coincide with the focal point of the pump light in the Y-axis direction, and then the detection light hits the center of the third focusing lens after passing through the second silver-coated reflector; Stage 4: The light beam emitted from the center of the third focusing lens hits the gold-coated hemisphere. The distance between the gold-coated hemisphere and the detector is adjusted so that the focused light spot hits the detector.

2. A multi-path weak absorption instrument calibration method according to claim 1, characterized in that: The wavelength of the pump light is 1064 nm, and the detection light is the light emitted by a 633 nm HE-NE laser.

3. A multi-path weak absorption instrument calibration method according to claim 1, characterized in that: The first focusing lens is a focusing lens with F=75 mm, the second focusing lens is a focusing lens with F=150 mm, and the third focusing lens is a focusing lens with F=50 mm.

4. A multi-path weak absorption instrument calibration method according to claim 1, characterized in that: During calibration, a beam profiler is used to detect the focus of the pump light and the probe light to ensure that the focus of the two beams is at the same position.

5. A multi-path weak absorption instrument, characterized in that: The multi-path weak absorber is calibrated by the multi-path weak absorber calibration method according to any one of claims 1 to 4.

6. A multi-optical path weak absorption instrument according to claim 5, characterized in that: It comprises a pump light emitter (1) and a detection light emitter (3); a first focusing lens (2), a three-dimensional XYZ axis stepping motor (7) and a power meter (8) are arranged in the direction of the pump light beam emission of the pump light emitter (1); and a beam analyzer (6) is mounted on the three-dimensional XYZ axis stepping motor (7); A second focusing lens (4) and a first silver-plated reflector (5) are arranged in the direction of the detection light beam of the detection light emitter (3). When in use, the focus of the detection light is overlapped with the focus of the pump light through the second focusing lens (4) and the first silver-plated reflector (5). A second silver-plated reflector (9), a third focusing lens (10) and a gold-plated hemisphere (11) are also arranged behind the detection light path. The three-dimensional XYZ axis stepping motor (7) and the beam analyzer (6) are arranged between the first silver-plated reflector (5) and the second silver-plated reflector (9). The focused light spot is projected onto the detector (12) through reflection of the gold-plated hemisphere (11).

7. A multi-path weak absorption instrument according to claim 6, characterized in that: The first focusing lens (2), the second focusing lens (4), the first silver-plated reflecting mirror (5), the second silver-plated reflecting mirror (9), the third focusing lens (10) and the gold-plated hemisphere (11) are arranged at the same height.

8. A multi-path weak absorption instrument according to claim 7, characterized in that: The multi-light path weak absorption instrument is electrically connected to a computer terminal for checking the light spot size.

9. Application of a multi-path weak absorption instrument calibration method as described in any one of claims 1 to 4 in calculating the absorption coefficient of a sample.

10. Use of the multi-path weak absorption instrument as described in any one of claims 5 to 8 in calculating the absorption coefficient of a sample.

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