Photoacoustic measuring device and adjusting method thereof

Abstract

The invention belongs to the technical field of film thickness measurement, and particularly relates to a photoacoustic measurement device and an adjusting method thereof. The method comprises the following steps: focusing detection light and / or pumping light on a knife edge, and obtaining the actual size of a detection light spot and the actual size of a pumping light spot; and the spot size of the detection spot and / or the pumping spot is adjusted to a preset size through the focus lens module and the power measuring device. According to the invention, the size and the power of the two focusing spots can be accurately obtained, and the precision of testing the thickness of the film is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of film thickness measurement, and particularly relates to a photoacoustic measurement device and an adjustment method thereof. Background Art

[0002] The semiconductor manufacturing process is essentially a process of manufacturing impurity regions (semiconductor thin films), wirings (metal films), and insulating films on a silicon wafer. Among them, the function of the metal film is to connect transistors, and the wiring can not only extend two-dimensionally in the horizontal direction, but also connect transistors in the vertical direction. Thus, plating a metal film is an important step in the semiconductor chip preparation process. Therefore, metal film thickness measurement is a key technology in the semiconductor chip preparation process.

[0003] The existing method for measuring the thickness of a metal thin film is a measurement method based on the photoacoustic effect and pump-probe technology. Its working principle is as follows: A femtosecond laser beam is divided into two beams of light - a pump beam and a probe beam by a beam splitter. The probe beam and the pump beam are focused on the same position of the thin film to be measured after passing through a lens. Among them, the pump beam induces the generation of sound waves. Through the change of the optical properties of the thin film to be measured by the sound waves, the reflectivity of the probe beam irradiated on the thin film to be measured changes. According to the time when the reflectivity changes and the propagation speed of the ultrasonic wave in the thin film to be measured, the thickness of the thin film to be measured is obtained.

[0004] Since the pump light spot has a Gaussian distribution, the central energy of the pump light spot is relatively high, and the energy fluctuation at the edge is relatively large. In a photoacoustic measurement device, the pump light spot is used to excite sound waves, and thus the film thickness of the sample to be measured is measured based on the influence of the sound waves on the probe light spot. In the actual application process, if the probe light spot is located in the edge region of the pump light spot, it will cause large fluctuations in the sound waves, resulting in inaccurate measurement of the film thickness. If the size of the probe light spot is larger than the size of the pump light spot, the sound waves excited by the pump light spot cannot affect the entire probe light spot. In addition, the actual sizes of the probe light spot and the pump light spot will also affect the measurement of the film thickness of the sample to be measured. Therefore, the size and power density of the focused light spots of the pump light spot and the probe light spot on the surface of the sample to be measured have a great influence on the detection signal. Ideally, it is required that the centers of the probe light spot and the pump light spot coincide, and the size of the probe light spot is smaller than the size of the pump light spot, so as to avoid the probe light spot being located in the region with unstable energy fluctuations of the pump light spot. In addition, it is also required that the actual sizes of the probe light spot and the pump light spot are the same as their respective preset sizes. Therefore, it is of great significance to accurately measure the actual sizes of the probe light spot and the pump light spot. And how to accurately obtain the sizes of the two focused light spots and the power of the focused light spots to improve the accuracy and repeatability of measuring the film thickness of the thin film (the test results of multiple tests are the same) has become one of the problems that need to be solved urgently by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention aims to provide a photoacoustic measurement device and an adjustment method thereof, so as to solve the problem that the prior art cannot accurately obtain the sizes of two focused light spots and the power of the focused light spots. The present invention can accurately obtain the sizes of two focused light spots and the power of the focused light spots, and improve the accuracy of measuring the thickness of a thin film.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows: A photoacoustic measurement device includes: A light source device that emits detection light and / or pump light. The optical path where the detection light is located is the detection optical path, and the optical path where the pump light is located is the pump optical path; A carrier stage that carries a sample to be measured and a knife edge. Moving the carrier stage causes the detection light and / or the pump light to be focused on the sample to be measured or the knife edge, so as to form a detection light spot and / or a pump light spot on the sample to be measured or the knife edge. When the light spot is focused on the sample to be measured, it is in the measurement state, and when the light spot is focused on the knife edge, it is in the adjustment state. The detection light is reflected to form a first measurement light, and the pump light is reflected to form a second measurement light; A focusing lens module that adjusts the spot size of the detection light spot and / or the pump light spot; A power measurement device that measures the power of the first measurement light and / or the second measurement light in the adjustment state; A controller that calculates the diameter of the detection light spot and / or the pump light spot according to the power of the first measurement light and / or the second measurement light; A detector that receives the first measurement light in the measurement state and determines the detection result of the sample to be measured according to the first measurement light.

[0007] Further, calculating the diameter of the detection light spot and / or the pump light spot according to the power of the first measurement light and / or the second measurement light is specifically as follows: Moving the carrier stage along the diameter direction of the detection light spot and / or the pump light spot, obtaining the first position indication value of the carrier stage corresponding to the critical maximum power before the power of the first measurement light and / or the second measurement light decreases, and the second position indication value of the carrier stage corresponding to the power decreasing to the critical minimum power. According to the difference between the first position indication value and the second position indication value, the diameter of the detection light spot and / or the pump light spot is correspondingly calculated; or Moving the carrier stage along the diameter direction of the detection light spot and / or the pump light spot, obtaining the third position indication value of the carrier stage corresponding to the critical minimum power before the power of the first measurement light and / or the second measurement light increases, and the fourth position indication value of the carrier stage corresponding to the power increasing to the critical maximum power. According to the difference between the third position indication value and the fourth position indication value, the diameter of the detection light spot and / or the pump light spot is correspondingly calculated.

[0008] Further, the light source device includes a laser, a beam splitter, a first shutter, and a second shutter; The laser beam emitted by the laser is incident on the beam splitter for beam splitting to obtain a detection light beam and a pump light beam; The pump light beam is emitted under the control of the first shutter; The detection light beam is emitted under the control of the second shutter.

[0009] Further, the photoacoustic measurement device further includes: an optical modulator provided in the pump optical path and / or the detection optical path; a time delay line provided in the pump optical path and / or the detection optical path.

[0010] Further, it includes an angle adjustment mechanism, and the angle adjustment mechanism adjusts the positions of the pump light spot and / or the detection light spot.

[0011] Further, the photoacoustic measurement device further includes a displacement stage module, and the focusing mirror module is placed on the displacement stage module, and the displacement stage module drives the focusing mirror module to move.

[0012] Further, the focusing mirror module includes one focusing mirror or two focusing mirrors, and each focusing mirror is correspondingly provided with a displacement stage; The focusing mirror module includes one focusing mirror, and the focusing mirror focuses the detection light beam and / or the pump light beam; or the focusing mirror module includes two focusing mirrors, and the two focusing mirrors respectively focus the detection light beam and the pump light beam.

[0013] Further, the power measurement device includes a power meter and a switching station, and the switching station switches the measurement position of the power meter so that the power meter measures the first measurement light beam, the second measurement light beam or is in a non-operating state.

[0014] A method for adjusting a photoacoustic measurement device, implemented by using the photoacoustic measurement device, specifically includes: Focus the detection light beam and / or the pump light beam on the knife edge to obtain the actual sizes of the detection light spot and the pump light spot; Adjust the spot sizes of the detection light spot and / or the pump light spot to a preset size through the focusing mirror module and the power measurement device.

[0015] Further, the preset sizes of the detection light spot and the pump light spot are obtained based on the working parameters of the laser of the light source device; the preset powers and preset power densities of the detection light spot and the pump light spot are obtained based on the output power of the laser.

[0016] Further, moving the carrier stage to focus the detection light beam and / or the pump light beam on the knife edge to obtain the actual sizes of the detection light spot and the pump light spot specifically includes: Obtain the first position indication value of the carrier stage corresponding to the critical maximum power before the power of the first measurement light beam decreases, Move the carrier stage along the diameter direction of the detection light spot, and obtain the second position indication value of the carrier stage corresponding to the power of the first measurement light ray decreasing to the critical minimum power. Calculate the diameter of the detection light spot according to the difference between the first position indication value and the second position indication value. Replace the first measurement light ray with the second measurement light ray, and repeat the above steps to obtain the diameter of the pump light spot; or Obtain the third position indication value of the carrier stage corresponding to the critical minimum power before the power of the first measurement light ray increases. Move the carrier stage along the diameter direction of the detection light spot, and obtain the fourth position indication value of the carrier stage corresponding to the power of the first measurement light ray increasing to the critical maximum power. Calculate the diameter of the detection light spot according to the difference between the third position indication value and the fourth position indication value. Replace the first measurement light ray with the second measurement light ray, and repeat the above steps to obtain the diameter of the pump light spot.

[0017] Further, the focusing mirror module of the photoacoustic measurement device includes a focusing mirror, and the displacement stage module of the photoacoustic measurement device includes a displacement stage; the focusing mirror is used to adjust the spot sizes of the detection light spot and the pump light spot. The specific method for adjusting the spot sizes of the detection light spot and the pump light spot to the preset sizes through the focusing mirror module and the power measurement device is as follows: Use the displacement stage to drive the focusing mirror to move, and adjust the distance between the focusing mirror and the carrier stage so that the actual size of at least one of the detection light spot and the pump light spot is the same as its respective preset size.

[0018] Further, detect whether the actual sizes of the detection light spot and the pump light spot are both the same as their respective preset sizes. If so, make the detector receive the first measurement light ray in the measurement state; otherwise, adjust the spot size of one of the detection light spot and the pump light spot through the focusing mirror module until the preset size, and use the power measurement device to measure the actual power value of the measurement light ray corresponding to the spot of the other one, and adjust the power of the current measurement light ray according to the actual power value of the current measurement light ray so that the spot power density of the other one is the same as the preset power density.

[0019] Further, the power measurement device of the photoacoustic measurement device includes a power meter; the specific steps for using the power measurement device to measure the actual power value of the measurement light ray corresponding to the spot of the other one are as follows: When the measurement light ray is the first measurement light ray, make the detection light ray be completely reflected by the knife edge, and use the power meter to measure the power of the first measurement light ray to obtain the actual power value of the first measurement light ray. When the measuring light is the second measuring light, the pump light is completely reflected by the knife edge, and a power meter is used to measure the power of the second measuring light to obtain the actual power value of the second measuring light.

[0020] Further, the photoacoustic measurement device includes a beam splitter and an attenuator. The specific adjustment method for adjusting the power of the current measuring light according to the actual power value of the current measuring light is to simultaneously adjust the attenuation value of the attenuator and the splitting ratio of the beam splitter.

[0021] Further, the focusing mirror module of the photoacoustic measurement device includes two focusing mirrors, and the displacement stage module of the photoacoustic measurement device includes two displacement stages; the focusing mirror is used to adjust the spot sizes of the detection spot and the pump spot. The specific method for adjusting the spot sizes of the detection spot and the pump spot to the preset sizes through the focusing mirror module is as follows: The pump light and the detection light respectively form a pump spot and a detection spot on the knife edge through the two focusing mirrors; According to the difference between the actual size and the preset size of the pump spot and the difference between the actual size and the preset size of the detection spot, the distances of the two focusing mirrors relative to the carrier stage are correspondingly adjusted so that the actual sizes of the detection spot and the pump spot are both the same as their respective preset sizes.

[0022] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) For the photoacoustic measurement device of the present invention, the adjustment of the spot size is realized by setting the focusing mirror module, so that the pump spot and the detection spot are consistent with their respective preset sizes; in addition, the present invention also sets a power measurement device to realize the real-time measurement of the powers of the detection light and the pump light. In order to avoid the influence of the power measurement device on the optical path of the photoacoustic measurement device in the measurement state, in the test state, the power meter is moved out of the optical path by using the power measurement device.

[0023] (2)The adjustment method of the photoacoustic measurement device according to the present invention provides a specific method for measuring the size of the focused spot based on the knife-edge method, that is, using a power measurement device to measure two critical states when the focused spot moves on the knife-edge, and calculating the actual size of the focused spot by combining the indicated values corresponding to the carrier stage. In addition, based on the setting method of the focusing lens module, the present invention adjusts the focused spot under two conditions. One is to set focusing lenses for the pump beam and the probe beam respectively, and by moving the two focusing lenses, make the pump beam and the probe beam both have the same preset size. The other is when using a single focusing lens to adjust the pump beam and the probe beam, if there is a situation where the probe beam and the pump beam cannot be simultaneously adjusted to their respective preset sizes, by changing the light transmission ratios of the attenuator and the beam splitter, changing the incident powers of the pump light and the probe light, and always keeping the power density of the focused spot that cannot be consistent with the preset size unchanged, the purpose of accurately obtaining the sizes of the two focused spots and the power of the focused spot is achieved, and the accuracy of measuring the film thickness is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings: FIG. 1(a) is a schematic diagram of the change of the knife-edge position in the X direction according to the embodiment of the present invention; FIG. 1(b) is a schematic diagram of the change of the knife-edge position in the Y direction according to the embodiment of the present invention; Figure 2 is a schematic structural diagram of the photoacoustic measurement device according to the embodiment of the present invention; Figure 3 is a schematic flowchart of the adjustment method of the photoacoustic measurement device according to the embodiment of the present invention.

[0025] DESCRIPTION OF THE REFERENCE NUMERALS 1. Carrier stage; 2. Knife-edge; 3. Light spot; 4. Sample to be measured; 5. Femtosecond laser; 6. Attenuator; 7. First mirror; 8. Beam splitter; 9. First shutter; 10. Optical modulator; 11. Second mirror; 12. Third mirror; 13. Second shutter; 14. Time delay line; 15. Fourth mirror; 16. Fifth mirror; 17. Sixth mirror; 18. Focusing lens; 19. Displacement stage; 20. Focusing lens; 21. Power measurement device; 22. Detector; 23. Light collector. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the following further details the present invention in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and do not constitute a limitation to the present invention.

[0027] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0028] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and defined, the terms "install", "connect", "couple" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0030] The following will detail the present invention with reference to the accompanying drawings and in conjunction with the embodiments.

[0031] On the one hand, the present invention provides a photoacoustic measurement device, comprising: a light source device that emits detection light and / or pump light, the optical path where the detection light is located being the detection optical path, and the optical path where the pump light is located being the pump optical path; a carrier stage that carries a sample to be measured and a knife edge, and moves the carrier stage to focus the detection light and / or pump light on the sample to be measured or the knife edge, so as to form a detection light spot and / or a pump light spot on the sample to be measured or the knife edge. When the light spot is focused on the sample to be measured, it is in the measurement state, and when the light spot is focused on the knife edge, it is in the adjustment state. The detection light is reflected to form a first measurement light, and the pump light is reflected to form a second measurement light; a focusing lens module that adjusts the spot size of the detection light spot and / or the pump light spot; a power measurement device that measures the power of the first measurement light and / or the second measurement light in the adjustment state; a controller that calculates the diameter of the detection light spot and / or the pump light spot according to the power of the first measurement light and / or the second measurement light; and a detector that receives the first measurement light in the measurement state and determines the detection result of the sample to be measured according to the first measurement light.

[0032] The photoacoustic measurement device provided by the present invention can realize the film thickness detection of the sample to be measured. By using the focusing lens module to adjust the spot size of the detection light spot and / or the pump light spot, and using the controller to calculate the diameter of the detection light spot and / or the pump light spot according to the power of the first measurement light and / or the second measurement light, the size and power of at least one focused light spot can be accurately obtained, so as to improve the accuracy and repeatability of measuring the film thickness.

[0033] It should be noted that the knife edge is integrated on the carrier stage, and the integration methods include fixing methods such as embedding, gluing, and mechanical connectors. The knife edge can be made of a standard wafer, etc.

[0034] In some embodiments, calculating the diameter of the detection light spot and / or the pump light spot according to the power of the first measurement light and / or the second measurement light is specifically as follows: moving the carrier stage along the diameter direction of the detection light spot and / or the pump light spot, obtaining the first position indication of the carrier stage corresponding to the critical maximum power before the power of the first measurement light and / or the second measurement light decreases, and the second position indication of the carrier stage corresponding to the power decreasing to the critical minimum power, and calculating the diameter of the detection light spot and / or the pump light spot corresponding to the difference between the first position indication and the second position indication; or, moving the carrier stage along the diameter direction of the detection light spot and / or the pump light spot, obtaining the third position indication of the carrier stage corresponding to the critical minimum power before the power of the first measurement light and / or the second measurement light increases, and the fourth position indication of the carrier stage corresponding to the power increasing to the critical maximum power, and calculating the diameter of the detection light spot and / or the pump light spot corresponding to the difference between the third position indication and the fourth position indication.

[0035] Specifically, as shown in FIGS. 1(a)-1(b), when the light spot 3 is completely incident on the knife edge 2, the beam to be measured is completely reflected by the knife edge 2. At this time, the power value measured by the power measurement device is the largest. As the carrier stage 1 under the knife edge 2 moves continuously (along the diameter direction of the cutting beam, and the knife edge 2 and the carrier stage 1 move simultaneously), the overlapping portion between the light spot 3 and the knife edge 2 will gradually decrease. At this time, the power value measured by the power measurement device is decreasing; when the light spot 3 does not overlap with the knife edge 2, the power value measured by the power measurement device is the smallest. In order to make the measured size of the light spot 3 more accurate, it is necessary to pay attention to the critical state here, that is, when the power of the light spot 3 changes from the maximum to the minimum, it is necessary to find the critical maximum power value before the light spot 3 starts to decrease, and the critical minimum power value when the light spot 3 decreases to the minimum, and vice versa. The position indication of the carrier stage 1 changes with the position change of the carrier stage 1. When the corresponding critical power values are found, record the position of the carrier stage 1, and obtain the diameter of the light spot 3 by calculating the difference between the above-mentioned critical maximum power value and critical minimum power value.

[0036] In some embodiments, the light source device includes a laser, a beam splitter, a second shutter, and a first shutter. The laser beam emitted by the laser is incident on the beam splitter for beam splitting to obtain a detection light beam and a pump light beam; the pump light beam is emitted under the control of the first shutter; the detection light beam is emitted under the control of the second shutter. Among them, the second shutter and the first shutter are mainly used to switch the optical path. In the adjustment state and the measurement state, the detection light beam and / or the pump light beam are selectively emitted according to the measurement and use requirements of the user.

[0037] In some embodiments, the laser can generally be a femtosecond laser; in some embodiments, the beam splitter can be a grating, a semi-transmissive semi-reflective mirror, a beam splitting prism, etc.

[0038] In some embodiments, the photoacoustic measurement device further includes: an optical modulator disposed in the pump optical path and / or the detection optical path; a time delay line disposed in the pump optical path and / or the detection optical path.

[0039] In some embodiments, the optical modulator and the time delay line can be disposed between the light source device and the focusing mirror module.

[0040] It should be noted that when performing photoacoustic measurement on the object to be measured (such as measuring the film thickness), it is required that there is a time delay between the pump light beam and the detection light beam incident on the object to be measured, and the time delay is adjustable. Therefore, the present invention provides a time delay line. And modulating the amplitude of the pump light beam in the measurement device can save costs, and modulating the pump light beam with periodic changes is convenient for subsequent signal extraction. Therefore, the present invention also provides an optical modulator.

[0041] In some embodiments, the photoacoustic measurement device further includes a displacement stage module. The focusing mirror module is placed on the displacement stage module, and the displacement stage module drives the focusing mirror module to move, so that the focusing mirror module approaches or moves away from the carrier stage 1.

[0042] In some embodiments, the focusing mirror module includes one focusing mirror or two focusing mirrors, and each focusing mirror is correspondingly provided with a displacement stage; the focusing mirror module includes one focusing mirror, and the focusing mirror focuses the detection light and / or the pump light; or the focusing mirror module includes two focusing mirrors, and the two focusing mirrors respectively focus the detection light and the pump light. In some examples, the displacement stage can be an electric displacement stage.

[0043] In some embodiments, the power measurement device includes a power meter and a switching stage. The switching stage switches the measurement position of the power meter, so that the power meter is respectively located in the pump optical path, the detection optical path, and the non-measurement position, so as to measure the first measurement light, the second measurement light, or be in a non-operating state.

[0044] It should be noted that the method of making the power meter measure the first measurement light, the second measurement light, or be in a non-operating state is not limited to the above method, and there are other methods. For example, a beam splitting prism (or other devices capable of beam splitting) is respectively provided in the pump optical path and the detection optical path, so that a part of the first measurement light or the second measurement light is incident on the power meter for power measurement, and the other part of the light is incident on the light collector or the detector to realize the film thickness measurement of the sample to be measured.

[0045] The following takes Figure 2 as an example to describe the working process of the photoacoustic measurement device as follows: The femtosecond pulsed laser emitted by the femtosecond laser 5 is incident on the beam splitter 8 successively through the attenuator 6 and the first mirror, and is split into detection light and pump light by the beam splitter 8. The optical path where the detection light is located is the detection optical path, and the optical path where the pump light is located is the pump optical path. Here, the optical modulator 10 is arranged on the pump optical path, and the time delay line 14 is arranged on the detection optical path. The pump light is incident on the surface of the sample to be measured 4 successively through the first shutter 9, the optical modulator 10, the second mirror 11, the third mirror 12, and the focusing mirror 18 located on the displacement stage 19, and ultrasonic signals are excited inside the material of the sample to be measured 4. The detection light is incident on the surface of the sample to be measured 4 successively through the second shutter 13, the time delay line 14, the fourth mirror 15, the fifth mirror 16, the sixth mirror 17, and the focusing mirror 18 located on the displacement stage 19. The presence of the time delay line 14 makes the detection light have a femtosecond-picosecond level Δt relative to the pump light sThe time delay. It should be noted that the focusing lens module here includes a focusing lens 18. The centers of the detection light spot and the pump light spot formed after the detection light and the pump light pass through the focusing lens 18 coincide, and the size of the detection light spot is smaller than that of the pump light spot, avoiding the detection light spot being located in the area where the energy of the pump light spot fluctuates, so as to ensure that the particles in the detected area are excited to the excited state. The first measurement light passes through the focusing lens 20 and the power measurement device 21 in sequence and is received by the detector 22, and the detection result of the sample 4 to be measured is determined according to the first measurement light. From the time delay △t between the detection light and the pump light s , a signal of the reflectivity of the first measurement light changing with the time delay can be obtained. By accurately measuring the time when the reflectivity change signal occurs and combining the sound velocity of the material of the sample 4 to be measured, the formula d = v s* t echo / 2 (where v s is the sound velocity in the material of the sample 4 to be measured, d is the thickness of the sample 4 to be measured, and t echo is the time when the reflectivity change signal occurs) can be used to calculate the thickness of the sample 4 to be measured.

[0046] As Figure 3 shown, on the other hand, the present invention also provides an adjustment method for a photoacoustic measurement device, which is implemented by using the photoacoustic measurement device, and specifically includes: using the controller to move the carrier table 1 to focus the detection light and / or the pump light on the knife edge 2, and obtaining the actual size of the detection light spot and the actual size of the pump light spot; using the controller to control the focusing lens module and the power measurement device 21 to adjust the light spot sizes of the detection light spot and / or the pump light spot until the preset sizes.

[0047] In some embodiments, the preset sizes of the detection light spot and the pump light spot are obtained based on the working parameters of the laser of the light source device; the preset power and preset power density of the detection light spot and the pump light spot are obtained based on the output power of the laser.

[0048] In some embodiments, moving the carrier stage 1 by using a controller to focus the detection light and / or the pump light on the knife edge 2 and obtaining the actual sizes of the detection light spot and the pump light spot specifically include: moving the carrier stage 1 by using the controller to change the relative position between the detection light spot and the knife edge 2, obtaining the first position indication of the carrier stage 1 corresponding to the critical maximum power before the power of the first measurement light decreases, moving the carrier stage 1 along the diameter direction of the detection light spot, obtaining the second position indication of the carrier stage 1 corresponding to the power of the first measurement light decreasing to the critical minimum power, calculating the diameter of the detection light spot by using the controller according to the difference between the first position indication and the second position indication, replacing the first measurement light with the second measurement light, and repeating the above steps to obtain the diameter of the pump light spot; or, moving the carrier stage 1 by using the controller to change the relative position between the detection light spot and the knife edge 2, obtaining the third position indication of the carrier stage 1 corresponding to the critical minimum power before the power of the first measurement light increases, moving the carrier stage 1 along the diameter direction of the detection light spot, obtaining the fourth position indication of the carrier stage 1 corresponding to the power of the first measurement light increasing to the critical maximum power, calculating the diameter of the detection light spot by using the controller according to the difference between the third position indication and the fourth position indication, replacing the first measurement light with the second measurement light, and repeating the above steps to obtain the diameter of the pump light spot.

[0049] Based on the setting mode of the focusing lens module, the adjustment method is adjusted under two conditions. The first condition is that the focusing lens module includes one focusing lens 18 and the displacement stage 19 module includes one displacement stage 19; the second condition is that the focusing lens module includes two focusing lenses 18 and the displacement stage 19 module includes two displacement stages 19. In the test state, the sizes of the pump light spot and the detection light spot are measured by the knife edge 2 method. If the size of the focused light spot changes, move the displacement stage 19 to change the position of the focusing lens 18 so that the sizes of the focused light spots corresponding to the pump light and the detection light always remain unchanged.

[0050] The following introduces the specific method for adjusting the spot sizes of the detection light spot and the pump light spot to the preset sizes by using the focusing lens module and the power measurement device 21 under the first condition: under the action of the controller, use the controller to control the displacement stage 19 to drive the focusing lens 18 to move, adjust the distance between the focusing lens 18 and the carrier stage 1 so that the actual size of at least one of the actual sizes of the detection light spot and the pump light spot is the same as their respective preset sizes.

[0051] In some embodiments, it is detected whether the actual sizes of the detection light spot and the pump light spot are both the same as their respective preset sizes. If so, the detector 22 is made to receive the first measurement light in the measurement state; otherwise, the light spot size of one of the detection light spot and the pump light spot is adjusted by the focusing lens module until the preset size, and the actual power value of the measurement light corresponding to the light spot of the other is measured by the power measurement device 21, and the power of the current measurement light is adjusted according to the actual power value of the current measurement light, so that the light spot power density of the other is the same as the preset power density.

[0052] It should be noted that if the light spot size of the detection light spot is adjusted until the preset size, the first shutter 9 is opened and the second shutter 13 is closed; if the light spot size of the pump light spot is adjusted until the preset size, the first shutter 9 is closed and the second shutter 13 is opened. After the adjustment of the light spot size of the detection light spot or the pump light spot is completed, the controller controls the power meter to move to the position corresponding to receiving the first measurement light or the second measurement light, so that the power meter measures the first measurement light or the second measurement light correspondingly. Accordingly, when measuring the first measurement light, the first shutter 9 needs to be opened and the second shutter 13 needs to be closed, while when measuring the second measurement light, the first shutter 9 needs to be closed and the second shutter 13 needs to be opened.

[0053] In some embodiments, under the action of the controller, the displacement stage 19 is used to drive the focusing lens 18 to move, and the actual size of the pump light spot is preferentially adjusted to be the same as its own preset size.

[0054] In some embodiments, the power measurement device 21 includes a power meter; the specific steps for the controller to control the power meter of the power measurement device 21 to switch the measurement circuit and measure the actual power value of the measurement light corresponding to the light spot of the other are as follows: when the measurement light is the first measurement light, the first shutter 9 is opened and the second shutter 13 is closed, the controller is used to move the carrier stage 1 so that the detection light is completely reflected by the knife edge 2, and the controller is used to control the power meter to measure the power of the first measurement light to obtain the actual power value of the first measurement light; when the measurement light is the second measurement light, the first shutter 9 is closed and the second shutter 13 is opened, the controller is used to move the carrier stage 1 so that the pump light is completely reflected by the knife edge 2, and the controller is used to control the power meter to measure the power of the second measurement light to obtain the actual power value of the second measurement light.

[0055] During the process of moving the displacement stage 19 under the control of the controller to change the position of the focusing mirror 18, if it is impossible to adjust the sizes of the pump light spot and the probe light spot to be consistent with their respective preset sizes simultaneously, the incident powers of the pump light and the probe light can be changed by changing the light transmission ratios of the attenuator 6 and the beam splitter, so that the power density of the focusing light spot that cannot be consistent with the preset size remains unchanged. Specifically, in some embodiments, the photoacoustic measurement device includes a beam splitter 8 and an attenuator 6. The specific adjustment method for adjusting the power of the current measurement light according to the actual power value of the current measurement light is: adjusting the attenuation value of the attenuator 6 and the beam splitting ratio of the beam splitter 8 simultaneously.

[0056] The following introduces the specific method for adjusting the spot sizes of the probe light spot and the pump light spot to the preset sizes through the focusing mirror module and the power measurement device 21 under the second condition: Open the first shutter 9 and the second shutter 13, and use the controller to move the carrier stage 1 so that the pump light and the probe light respectively form a pump light spot and a probe light spot on the knife edge 2 through two focusing mirrors 18; According to the difference between the actual size and the preset size of the pump light spot and the difference between the actual size and the preset size of the probe light spot, the controller controls the two displacement stages 19 to move, correspondingly adjusting the distances of the two focusing mirrors 18 relative to the carrier stage 1, so that the actual sizes of the probe light spot and the pump light spot are both the same as their respective preset sizes.

[0057] It should be noted that when changing the sizes of the probe light spot and the pump light spot only through one displacement stage 19, there may be a situation where it is impossible to adjust the probe light spot and the pump light spot to be consistent with their respective preset sizes simultaneously. If such a situation exists, a focusing mirror 18 and a corresponding displacement stage 19 can be respectively arranged above the respective focusing positions of the probe light spot and the pump light spot, so that the probe light and the pump light are independently focused on the two focusing mirrors 18, adjusting the corresponding displacement stage 19, respectively adjusting the sizes of the probe light spot and the pump light spot, so that the probe light spot and the pump light spot are consistent with their respective preset sizes, avoiding the occurrence of the above situation. Measure the actual sizes of the pump light spot and the probe light spot by the knife edge method. If the size of the focusing light spot changes, move the displacement stage 19 to change the position of the focusing mirror 18, so that the sizes of the focusing light spots corresponding to the pump light and the probe light are always the same as their respective preset sizes.

[0058] It should be understood that the various forms of the processes shown above can be used, reordering, adding or deleting steps. For example, the steps recorded in the disclosure of the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and no limitation is made herein.

[0059] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A photoacoustic measurement device, characterized in that, Comprising: A light source device that emits detection light and / or pump light. The optical path where the detection light is located is the detection optical path, and the optical path where the pump light is located is the pump optical path. A carrier stage that carries the sample to be measured and a knife edge. The carrier stage is moved to focus the detection light and / or pump light on the sample to be measured or the knife edge, so as to form a detection light spot and / or a pump light spot on the sample to be measured or the knife edge. When the light spot is focused on the sample to be measured, it is in the measurement state, and when the light spot is focused on the knife edge, it is in the adjustment state. The detection light is reflected to form a first measurement light, and the pump light is reflected to form a second measurement light. A focusing lens module that adjusts the spot size of the detection light spot and / or the pump light spot. A power measurement device that measures the power of the first measurement light and / or the second measurement light in the adjustment state. A controller that calculates the diameter of the detection light spot and / or the pump light spot according to the power of the first measurement light and / or the second measurement light. A detector that receives the first measurement light in the measurement state and determines the detection result of the sample to be measured according to the first measurement light.

2. The photoacoustic measurement device according to claim 1, characterized in that, Calculating the diameter of the detection light spot and / or the pump light spot according to the power of the first measurement light and / or the second measurement light, specifically: Moving the carrier stage along the diameter direction of the detection light spot and / or the pump light spot, obtaining the first position indication value of the carrier stage corresponding to the critical maximum power before the power of the first measurement light and / or the second measurement light decreases, and the second position indication value of the carrier stage corresponding to the power decreasing to the critical minimum power. According to the difference between the first position indication value and the second position indication value, the diameter of the detection light spot and / or the pump light spot is correspondingly calculated; or Moving the carrier stage along the diameter direction of the detection light spot and / or the pump light spot, obtaining the third position indication value of the carrier stage corresponding to the critical minimum power before the power of the first measurement light and / or the second measurement light increases, and the fourth position indication value of the carrier stage corresponding to the power increasing to the critical maximum power. According to the difference between the third position indication value and the fourth position indication value, the diameter of the detection light spot and / or the pump light spot is correspondingly calculated.

3. The photoacoustic measurement device according to claim 1, characterized in that, The light source device includes a laser, a beam splitter, a first shutter, and a second shutter. The laser beam emitted by the laser is incident on the beam splitter for beam splitting to obtain detection light and pump light. The detection light is emitted under the control of the first shutter. The pump light is emitted under the control of the second shutter.

4. The photoacoustic measurement device according to claim 1, characterized in that, The photoacoustic measurement device further includes: an optical modulator provided in the pump optical path and / or the detection optical path; a time delay line provided in the pump optical path and / or the detection optical path.

5. The photoacoustic measurement device according to claim 1, characterized in that Including an angle adjustment mechanism that adjusts the position of the pump light spot and / or the detection light spot.

6. The photoacoustic measurement device according to claim 1, characterized in that, The photoacoustic measurement device further includes a displacement stage module. The focusing lens module is placed on the displacement stage module, and the displacement stage module drives the focusing lens module to move.

7. The photoacoustic measurement device according to claim 6, characterized in that, The focusing lens module includes one focusing lens or two focusing lenses, and each focusing lens is correspondingly provided with a displacement stage. The focusing lens module includes one focusing lens that focuses the detection light and / or the pump light; or the focusing lens module includes two focusing lenses that respectively focus the detection light and the pump light.

8. The photoacoustic measurement device according to claim 1, characterized in that, The power measurement device includes a power meter and a switching station. The switching station switches the measurement position of the power meter, enabling the power meter to measure a first measurement light ray, a second measurement light ray, or to be in a non-operating state.

9. A method for adjusting a photoacoustic measurement device, implemented by using the photoacoustic measurement device according to any one of claims 1-8, characterized in that, Specifically, it includes: Focusing the probe light ray and / or the pump light ray on the knife edge to obtain the actual size of the probe light spot and the actual size of the pump light spot; Adjusting the spot size of the probe light spot and / or the pump light spot through the focusing lens module and the power measurement device until a preset size is reached.

10. The adjustment method of the photoacoustic measurement device according to claim 9, characterized in that, The preset size of each of the probe light spot and the pump light spot is obtained based on the operating parameters of the laser of the light source device; the preset power and preset power density of each of the probe light spot and the pump light spot are obtained based on the output power of the laser.

11. The adjustment method of the photoacoustic measurement device according to claim 9, characterized in that, Moving the carrier stage to focus the probe light ray and / or the pump light ray on the knife edge to obtain the actual size of the probe light spot and the pump light spot specifically includes: Obtaining the first position indication of the carrier stage corresponding to the critical maximum power before the power of the first measurement light ray decreases, Moving the carrier stage along the diameter direction of the probe light spot to obtain the second position indication of the carrier stage corresponding to the power of the first measurement light ray decreasing to the critical minimum power, Calculating the diameter of the probe light spot based on the difference between the first position indication and the second position indication, Replacing the first measurement light ray with the second measurement light ray and repeating the above steps to obtain the diameter of the pump light spot; or, Obtaining the third position indication of the carrier stage corresponding to the critical minimum power before the power of the first measurement light ray increases, Moving the carrier stage along the diameter direction of the probe light spot to obtain the fourth position indication of the carrier stage corresponding to the power of the first measurement light ray increasing to the critical maximum power, Calculating the diameter of the probe light spot based on the difference between the third position indication and the fourth position indication, Replacing the first measurement light ray with the second measurement light ray and repeating the above steps to obtain the diameter of the pump light spot.

12. The adjustment method of the photoacoustic measurement device according to claim 9, characterized in that, The focusing lens module of the photoacoustic measurement device includes a focusing lens, and the displacement stage module of the photoacoustic measurement device includes a displacement stage; the focusing lens is used to adjust the spot size of the probe light spot and the pump light spot. The specific method for adjusting the spot size of the probe light spot and the pump light spot through the focusing lens module and the power measurement device until a preset size is reached is: Using the displacement stage to drive the focusing lens to move, adjusting the distance of the focusing lens relative to the carrier stage to make the actual size of at least one of the probe light spot and the pump light spot the same as their respective preset sizes.

13. The adjustment method of the photoacoustic measurement device according to claim 12, characterized in that, Detecting whether the actual sizes of the probe light spot and the pump light spot are both the same as their respective preset sizes. If so, enabling the detector to receive the first measurement light ray in the measurement state; otherwise, adjusting the spot size of one of the probe light spot and the pump light spot through the focusing lens module until the preset size is reached, and using the power measurement device to measure the actual power value of the measurement light ray corresponding to the spot of the other one, and adjusting the power of the current measurement light ray according to the actual power value of the current measurement light ray to make the power density of the spot of the other one the same as the preset power density.

14. The adjustment method of the photoacoustic measurement device according to claim 13, characterized in that, The power measurement device of the photoacoustic measurement device includes a power meter; the specific steps for measuring the actual power value of the measurement light corresponding to the light spot of another object using the power measurement device are as follows: When the measurement light is the first measurement light, make the detection light be completely reflected by the knife edge, and use the power meter to measure the power of the first measurement light to obtain the actual power value of the first measurement light; When the measurement light is the second measurement light, make the pump light be completely reflected by the knife edge, and use the power meter to measure the power of the second measurement light to obtain the actual power value of the second measurement light.

15. The adjustment method of the photoacoustic measurement device according to claim 13, characterized in that, The photoacoustic measurement device includes a beam splitter and an attenuator. The specific adjustment method for adjusting the power of the current measurement light according to the actual power value of the current measurement light is as follows: adjust the attenuation value of the attenuator and the splitting ratio of the beam splitter simultaneously.

16. The adjustment method of the photoacoustic measurement device according to claim 9, characterized in that, The focusing lens module of the photoacoustic measurement device includes two focusing lenses, and the displacement stage module of the photoacoustic measurement device includes two displacement stages; the focusing lens is used to adjust the spot sizes of the detection light spot and the pump light spot. The specific method for adjusting the spot sizes of the detection light spot and the pump light spot to the preset size through the focusing lens module is as follows: Make the pump light and the detection light respectively form a pump light spot and a detection light spot on the knife edge through two focusing lenses; According to the difference between the actual size and the preset size of the pump light spot and the difference between the actual size and the preset size of the detection light spot, correspondingly adjust the distances of the two focusing lenses relative to the carrier stage so that the actual sizes of the detection light spot and the pump light spot are both the same as their respective preset sizes.

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