A method for calibrating a multi-path weak absorption instrument

Abstract

The present application relates to a kind of multi-light path weak absorption instrument calibration method.The present application relates to a kind of multi-light path weak absorption instrument calibration method, including setting height, control light and entering position point, shielding adjustment operation and four stages of debugging operation, with simple structure, ensure the effectiveness and reliability of multi-light path focal point position, with the advantages of good collection effect, high precision.In addition, the present application also proposes a kind of multi-light path weak absorption instrument, including pump light emitter, probe light emitter, first focusing lens, three-dimensional XYZ axis stepping motor, power meter, second focusing lens, first silver-coated mirror, second silver-coated mirror, third focusing lens, gold-coated hemisphere and detector, to solve the uncertain factors of pump light focal point, the accurate determination of the size of two laser probe light coincident position and light spot, can more accurately determine the size of pump light focusing light spot and the position of light spot, and a kind of multi-light path weak absorption instrument calibration method is used in calculating the absorption coefficient of sample, with higher precision, more reliable data.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photoelectric product measurement, in particular to a multi-light-path weak absorption instrument calibration method. BACKGROUND

[0002] The existing technology adopts the color chart indication to calibrate the focal point position when calibrating the multi-light-path weak absorption instrument. When the focal points of the pump light and the probe light are not determined, the focal length position of the probe light needs to be blocked to test the focal length position of the pump light. When the color chart is used to measure the focal point position of the pump light, the position of the smallest light spot needs to be determined by the naked eye. Here, there are large errors of the uncertainty and instability of the focal point position. After the focal point position of the pump light is preliminarily found, the focal point position is made to hit the focal point position of the pump light by moving the focusing lens forward and backward according to the focal length of the focusing lens on the probe light path. The above method has the problems of instability of the pump light focal point, uncertainty of the probe light focal point and other factors interfering with the photothermal deflection signal. The photothermal deflection signal is not strong enough, which can cause large test result errors, large noise influence and low sensitivity.

[0003] Therefore, the present application provides a multi-light-path weak absorption instrument calibration method to solve the problems of focal point uncertainty factors, two laser light overlapping positions and accurate determination of the light spot size. SUMMARY

[0004] (1) Technical problem to be solved

[0005] The present application aims to provide a multi-light-path weak absorption instrument calibration method.

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

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

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

[0009] The present application adopts a beam analyzer in the process of calibrating the multi-light-path weak absorption instrument, which can more accurately determine the size and position of the pump light focusing light spot, better observe through the external computer terminal, better overlap the pump light and the probe light, effectively improve the strength of the photothermal deflection signal, make the test result accurate and reliable, and stable in repeatability.

[0010] (2) Technical scheme

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

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

[0013] I. Set the height: the center height of the pump light and probe light is fixed, and all the mirrors are kept at the same height on the same optical axis, wherein the mirrors include three focusing lenses with different focal lengths, a first silver-coated mirror and a second silver-coated mirror;

[0014] II. Control the position of the light: the pump light passes through the first focusing lens and hits the power meter, and the probe light passes through the second focusing lens and hits the gold-coated half-sphere through the reflection of the first silver-coated mirror and the second silver-coated mirror, and finally hits the detector through the reflection of the gold-coated half-sphere;

[0015] III. Shielding adjustment operation: a three-dimensional XYZ-axis stepper motor is provided at the position where the first focusing lens transmits the light beam, and a light beam analyzer is installed on the three-dimensional XYZ-axis stepper motor. During the operation, the light path of the probe light is directed to the second silver-coated mirror through the first silver-coated mirror, and the three-dimensional XYZ-axis stepper motor is arranged between the first silver-coated mirror and the second silver-coated mirror;

[0016] IV. Debugging operation:

[0017] First stage: block the probe light, at this time, the pump light is in a normal emission state, and the light beam analyzer on the three-dimensional XYZ-axis stepper motor is moved along the Z-axis direction at the position of the pump light focus. Then, the spot size is checked on the computer using the light beam analyzer software, and the minimum spot position is marked and the current coordinate position of the three-dimensional XYZ-axis stepper motor is recorded;

[0018] Second stage: block the pump light and open the probe light, and set the position of the light beam analyzer unchanged or at the pump light focus position in the first stage. Move the second focusing lens at the back end of the probe light beam emission position forward and backward, adjust the position of the second focusing lens, and let the focus continue to hit the light beam analyzer. Finally, the focus position of the probe light is the same as the Z-axis position of the pump light focus;

[0019] Third stage: after the focus position of the probe light is the same as the Z-axis direction focus position of the pump light, fix the position of the second focusing lens, rotate the first silver-coated mirror to make the focus position of the probe light coincide with the Y-axis direction focus position of the pump light, and then the probe light hits the center of the third focusing lens after passing through the second silver-coated mirror;

[0020] Fourth stage: the light beam emitted through the center of the third focusing lens hits the gold-coated half-sphere, and the distance between the gold-coated half-sphere and the detector is adjusted to make the focused spot hit the detector.

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

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

[0023] Further, when calibrating, a beam analyzer is used to detect the focal points of the pump light and the probe light, so as to ensure that the focal points of the two beams of light are on the same position.

[0024] Further, the signal receiving platform is composed of a second silver-coated mirror, a third focusing lens, a gold-coated hemisphere and a detector.

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

[0026] The second aspect of the present application 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] Further, the multi-path weak absorption instrument comprises a pump light emitter and a probe light emitter, a first focusing lens, a three-dimensional XYZ axis stepping motor and a power meter are arranged on the pump light beam emission direction of the pump light emitter, and a beam analyzer is arranged on the three-dimensional XYZ axis stepping motor;

[0029] The probe light beam emission direction of the probe light emitter is provided with a second focusing lens and a first silver-coated mirror, and the focal points of the probe light and the pump light are overlapped through the second focusing lens and the first silver-coated mirror during use; a second silver-coated mirror, a third focusing lens and a gold-coated hemisphere are further arranged behind the probe light path, the three-dimensional XYZ axis stepping motor and the beam analyzer are arranged between the first silver-coated mirror and the second silver-coated mirror, and the focused light spot is reflected by the gold-coated hemisphere and is shot on the detector.

[0030] Further, the first focusing lens, the second focusing lens, the first silver-coated mirror, the second silver-coated mirror, the third focusing lens and the gold-coated hemisphere are arranged on the same height.

[0031] Further, the multi-path weak absorption instrument is electrically connected with a computer terminal for viewing the size of the light spot.

[0032] Further, the beam analyzer is used to detect the focal points of the pump light and the probe light, and it is necessary to ensure that the focal points of the two beams of light are on the same position.

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

[0034] The multi-path weak absorption instrument calibration method is applied to calculating the absorption coefficient of a sample.

[0035] In a fourth aspect of the present application, there is provided:

[0036] Application of the multi-path weak absorption instrument in calculating the absorption coefficient of a sample.

[0037] (3) Advantageous effects

[0038] The present application has the advantages that: the present application overcomes the problems in the prior art that the instability of the focus of the pump light, the uncertainty of the focus of the probe light and other factors interfere with the photothermal deflection signal, and the photothermal deflection signal is not strong enough, which leads to large test result errors, large noise influence and low sensitivity. In the process of calibrating the multi-path weak absorption instrument, the present application uses a beam analyzer to solve the problems of the uncertainty of the focus of the pump light, the coincidence position of the two beams of probe light and the accurate determination of the size of the light spot, can more accurately determine the size of the focused light spot of the pump light and the position of the light spot, and can better observe through an external computer terminal, can better overlap the pump light and the probe light, effectively improve the strength of the photothermal deflection signal, make the test result accurate and reliable, and stable in repeatability, and then make the probe light pass through the refractive index gradient region of the sample to be distorted, better calculate the absorption coefficient of the sample by measuring the distortion degree of the probe light, and obtain the absorption of the sample. The present application has the advantages of simple structure, effective multi-path focus position, good collection effect, high precision and high reliability, and is worth popularizing and using. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 Fig. 1 is a three-dimensional structural schematic view of a multi-path weak absorption instrument according to the present application.

[0040] Figure 2 Fig. 2 is a top view structural schematic view of a multi-path weak absorption instrument according to the present application.

[0041] Figure 3 Fig. 3 is a view of the separation of the two beams of light of the pump light and the probe light displayed on the computer terminal during use of the present application.

[0042] Figure 4 Fig. 4 is a view of the coincidence of the two beams of light of the pump light and the probe light displayed on the computer terminal during use of the present application.

[0043] Figure 5 Fig. 5 is a view of the two beams of light coinciding to block the 633nm probe light and only the 1064nm pump light during use of the present application.

[0044] Figure 6For the use of the present application, two beams of light coincide to block 1064 nm pump light, and only 633 nm probe light is viewed. In the figure: 1 pump light emitter, 2 first focusing lens, 3 probe light emitter, 4 second focusing lens, 5 first silver-coated mirror, 6 beam analyzer, 7 three-dimensional XYZ axis stepping motor, 8 power meter, 9 second silver-coated mirror, 10 third focusing lens, 11 gold-coated hemisphere, 12 detector. DETAILED DESCRIPTION

[0045] The present application can be better understood according to the following examples. However, it is readily apparent to those skilled in the art that the specific materials, process conditions and results described in the examples are illustrative only and are not intended to limit the present application as described in the claims.

[0046] The experimental materials and reagents used are all conventional consumables and reagents available commercially, unless otherwise specified.

[0047] Example 1:

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

[0049] At this time, the sample stage is installed on the X-axis motor, and the beam analyzer 6 is placed on the sample stage; the second silver-coated mirror 9, the third focusing lens 10, the gold-coated hemisphere 11 and the detector 12 form a signal receiving platform; the distance from the first silver-coated mirror 5 to the second silver-coated mirror 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, the Z-axis direction is the left-right direction in the Figure 2 , that is, the direction of the pump light emission; the Y-axis direction is the up-down direction in the Figure 2 , that is, the direction of the probe light emission. In the present device, the X-axis uses 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 the present scheme;

[0051] Then turn on the pump light, block the probe light, and use the beam analyzer 6 to move along the Z-axis direction at the position of the pump light focus, that is, move horizontally in the Figure 2 , view the spot size on the computer side, mark and record the current coordinate position of the three-dimensional XYZ axis stepping motor at the place where the spot is smallest;

[0052] The pump light is blocked, the probe light is opened, the F=150mm second focusing lens 4 is moved forward and backward to make the focal point on the beam analyzer 6, and the position of the beam analyzer 6 at this time is unchanged and is at the pump light focal point position, the focal point position of the probe light is the same as the pump light focal point Z-axis position, the F=150mm second focusing lens 4 is fixed, the first silver-coated mirror 5 is rotated to make the probe light focal point coincide with the pump light Y-axis direction focal point, and the probe light hits the center of the F=50mm third focusing lens 10 after passing through the second silver-coated mirror 9, and the distance between the gold-coated hemisphere 11 and the detector 12 is adjusted to make the focused light spot hit the detector 12;

[0053] It should be noted that in the optical field, the gold-coated hemisphere 11 generally refers to a semispherical optical element, the surface of which is coated with a layer of gold. This special treatment can improve the light reflecting ability of the hemisphere, especially in the infrared waveband. The gold-coated hemisphere 11 is commonly used in the fields of optical measurement, laser system, infrared imaging and spectroscopy, because the reflectivity of gold is high, it can provide more accurate measurement results and clearer image quality;

[0054] In the above process, according to the light-heat deflection technology, the center height is fixed and all lens centers are kept on the unified optical axis at this height, the 1064nm probe light passes through the F=75mm first focusing lens 2 and hits the power meter 8, the 633nm HE-NE probe light passes through the F=150mm second focusing lens 4 and is reflected by the two silver-coated mirrors and then passes through the F=50mm third focusing lens 10 to hit the gold-coated hemisphere 11, and the final focal point after reflection by the gold-coated hemisphere 11 hits the detector 12;

[0055] When the above operation is completed, the multi-path weak absorption instrument calibration effect is realized.

[0056] Embodiment 2:

[0057] A multi-path weak absorption instrument, comprising a pump light emitter 1 and a probe light emitter 3, the pump light emitter 1 emits a 1064nm pump light beam, and the probe light emitter 3 is a 633nm HE-NE laser, and emits a probe light beam from 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 on the pump light beam emission direction of the pump light emitter 1, a beam analyzer 6 is arranged on the three-dimensional XYZ-axis stepping motor 7, and the specification of the first focusing lens 2 is F=75mm focusing lens;

[0058] The probe light beam emission direction of the probe light emitter 3 is provided with a second focusing lens 4 and a first silver-coated mirror 5, the specification of the second focusing lens 4 is F=150mm focusing lens, in use, the probe light focus and the pump light focus are overlapped through the second focusing lens 4 and the first silver-coated mirror 5; a second silver-coated mirror 9, a third focusing lens 10 and a gold-coated hemisphere 11 are further arranged behind the probe light path, the specification of the third focusing lens 10 is F=50mm focusing lens, the three-dimensional XYZ axis stepping motor 7 and the light beam analyzer 6 are arranged between the first silver-coated mirror 5 and the second silver-coated mirror 9, in calibration, the light beam analyzer 6 is arranged at the pump light and the probe light focus; finally, the focused light spot is reflected by the gold-coated hemisphere 11 and is shot on the detector 12, wherein the first focusing lens 2, the second focusing lens 4, the first silver-coated mirror 5, the second silver-coated mirror 9, the third focusing lens 10 and the gold-coated hemisphere 11 are arranged at the same height, in order to better observe the light spot condition, the multi-light-path weak absorption instrument is electrically connected with the computer terminal for observing the light spot size.

[0059] The multi-light-path calibration method has simple structure, guarantees 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 in the application of calculating the absorption coefficient of the sample adopts surface thermal lens technology, utilizes the distortion of the film layer caused by the photo-thermal effect of the optical material or the film under the irradiation of the probe light intensity, that is, photo-thermal deformation, a standard probe light beam will produce coupling diffraction effect after passing through the curved surface, and the deformation of the film layer surface is obtained by testing the diffraction effect, so that many optical properties (including weak absorption characteristics) of the optical film and the material are obtained, the sample to be measured generates the density change of the laser working substance due to the temperature rise and the thermal deformation of the crystal surface due to the temperature rise under the action of the pump light; when the laser works, the heat generated will cause the deformation of the crystal or the working substance surface, the probe light passes through the refractive index gradient region of the sample and is distorted, and the absorption of the sample is obtained by measuring the distortion degree of the probe light.

[0060] The positions of the two light foci are found by using the light beam analyzer, the Z-axis distance is recorded, the clamp is placed, and the error distance of the sample and the Z-axis of the light beam analyzer is calculated, so that the foci of the two lasers can be ensured to be shot on the sample.

[0061] In order to fully prove that the present application is superior to the prior art, the attached drawings are Figures 3-6 In the state, Figure 5 The centroid coordinates in the state are (X7010, Y2448), Figure 6The centroid coordinates of the state are (X6959, Y2421), at this time the focal point centroid coordinates of the two beams are within 52um, which cannot be determined by naked eye judging the color chart with the prior art, therefore, the light beam analyzer can more accurately, conveniently and quickly determine the coincidence degree of the two light spots. The exemplary embodiments of the scheme proposed by the present disclosure are described in detail above with reference to the preferred embodiments, however, those skilled in the art can understand that various modifications and improvements can be made to the above specific embodiments, and various technical features and structures proposed by the present disclosure can be combined without departing from the concept of the present disclosure, and the protection scope of the present disclosure is determined by the appended claims.

Claims

1. A calibration method for a multi-path weak absorber, characterized in that, It comprises the following steps: I. Set the height: fix the center height of the pump light and the probe light, and keep all the mirrors centered at this height on the same optical axis, wherein the mirrors include three focusing lenses with different focal lengths, a first silver-coated mirror and a second silver-coated mirror; II. Control the light to enter the position point: the pump light passes through the first focusing lens and hits the power meter, the probe light passes through the second focusing lens and is reflected by the first silver-coated mirror and the second silver-coated mirror to pass through the third focusing lens and hit the gold-coated hemisphere, and the light reflected by the gold-coated hemisphere finally hits the detector; III. Shielding adjustment operation: a three-dimensional XYZ-axis stepping motor is arranged at the position where the first focusing lens transmits the light beam backward, and a light beam analyzer is mounted on the three-dimensional XYZ-axis stepping motor. During the operation, the light path of the probe light is shot to the second silver-coated mirror through the first silver-coated mirror, and the three-dimensional XYZ-axis stepping motor is arranged between the first silver-coated mirror and the second silver-coated mirror; IV. Debugging operation: First stage: block the probe light, at this time the pump light is in the normal emission state, use the light beam analyzer on the three-dimensional XYZ-axis stepping motor to move along the Z-axis direction at the position of the pump light focus, then use the light beam analyzer software on the computer to check the spot size, mark the place where the spot size is the smallest and record the coordinate position of the three-dimensional XYZ-axis stepping motor at this time; Second stage: block the pump light and open the probe light, set the light beam analyzer position unchanged or at the pump light focus position in the first stage, move the position of the second focusing lens at the back end of the probe light beam emission, adjust the position of the second focusing lens to make the focus continue to hit the light beam analyzer, and finally make the focus position of the probe light the same as the Z-axis position of the pump light; Third stage: after the focus position of the probe light is the same as the Z-axis focus position of the pump light, fix the position of the second focusing lens, rotate the first silver-coated mirror to make the focus of the probe light coincide with the focus of the pump light in the Y-axis direction, and then the probe light hits the center of the third focusing lens after passing through the second silver-coated mirror; Fourth stage: the light beam emitted from the center of the third focusing lens hits the gold-coated hemisphere, and the distance between the gold-coated hemisphere and the detector is adjusted to make the focused spot hit the detector; The wavelength of the pump light is 1064nm, and the probe light uses the light emitted by a 633nm HE-NE laser; The first focusing lens is a F=75mm focusing lens, the second focusing lens is a 150mm focusing lens, and the third focusing lens is a F=50mm focusing lens; During calibration, use the light beam analyzer to detect the focus of the pump light and the probe light to ensure that the focus of the two light beams is at the same position.

2. A multi-pass, weak absorption spectrometer, characterized in that, The multi-light-path weak absorption instrument is calibrated by the multi-light-path weak absorption instrument calibration method of claim 1.

3. A multi-optical-path weak absorption instrument according to claim 2, characterized in that, It comprises a pump light emitter (1) and a probe light emitter (3), a first focusing lens (2), a three-dimensional XYZ-axis stepping motor (7) and a power meter (8) are arranged on the pump light beam emission direction of the pump light emitter (1), and a light beam analyzer (6) is assembled on the three-dimensional XYZ-axis stepping motor (7). The probe light beam emission direction of the probe light emitter (3) is provided with a second focusing lens (4) and a first silver-coated mirror (5), in use, the probe light focus and the pump light focus are overlapped through the second focusing lens (4) and the first silver-coated mirror (5); a second silver-coated mirror (9), a third focusing lens (10) and a gold-coated hemisphere (11) are further arranged behind the probe light path, the three-dimensional XYZ axis stepping motor (7) and the light beam analyzer (6) are arranged between the first silver-coated mirror (5) and the second silver-coated mirror (9), and the focused light spot is reflected by the gold-coated hemisphere (11) and is shot on the detector (12).

4. A multi-optical-path weak absorption instrument according to claim 3, characterized in that, The first focusing lens (2), the second focusing lens (4), the first silver-coated mirror (5), the second silver-coated mirror (9), the third focusing lens (10) and the gold-coated hemisphere (11) are arranged at the same height.

5. A multi-optical-path weak absorption instrument according to claim 4, characterized in that, The multi-path weak absorption instrument is electrically connected with a computer terminal for viewing the size of the light spot.

6. Application of the calibration method of the multi-path weak absorption instrument according to claim 1 in calculating the absorption coefficient of a sample.

7. Application of the multi-path weak absorption instrument according to any one of claims 2-5 in calculating the absorption coefficient of a sample.

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