A temperature measurement device and method based on laser reflection

Abstract

The present application discloses a temperature measurement device and method based on laser reflection, which relates to the field of laser technology. The device includes: a laser, an optical switch, a polarization beam splitter, a quarter wave plate, an objective lens of a microscope, a reference signal detector, a reflection signal detector, and a phase-locked amplifier. The present application efficiently obtains reflected laser light through a polarization beam splitter and a quarter wave plate, which can improve the resolution of imaging and reduce the thermal impact of reflected laser light on the sample to be measured; in the scheme provided by the present application, a differential detector including a reference signal detector and a reflection signal detector is introduced, which can effectively reduce the impact of noise on signal detection and improve the stability and accuracy of imaging; in the scheme provided by the present application, a phase-locked amplifier is used to perform phase-locked analysis on the reference signal detector and the reflection signal, which can quickly and accurately extract temperature information and improve the accuracy and speed of temperature measurement.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a temperature measurement device and method based on laser reflection. Background Art

[0002] With the rapid development of science and technology, the demand for high-speed and accurate measurement of thermal properties of materials at the microscopic scale is growing. Based on the thermal properties of materials, the temperature of devices can be measured, and the design and production process of micro-nano structures such as semiconductor devices can also be tested.

[0003] In related technologies, such as thermal reflection measurement technology, the relationship between the optical reflectivity of a material and temperature can be used to achieve high spatial resolution temperature measurement. However, the efficiency of measuring device temperature in related technologies is still relatively low, and the optical signal is easily masked by noise, resulting in inaccurate measurement results. Summary of the invention

[0004] In order to improve the accuracy and efficiency of temperature measurement of microscopic materials, the present application provides a temperature measurement device and method based on laser reflection. The technical solution is as follows:

[0005] In a first aspect, the present application provides a temperature measurement device based on laser reflection, the device comprising:

[0006] The optical modulation module includes a laser and an optical switch, wherein the laser is used to output an incident laser of a polarization state, and the optical switch is used to modulate the incident laser; a polarization beam splitter, a quarter wave plate, and an objective lens of a microscope are sequentially arranged along the incident optical path of the modulated incident laser; the polarization beam splitter is used to separate the modulated incident laser into a reference laser and an irradiation laser, and the irradiation laser is irradiated on the surface of the sample to be measured;

[0007] A differential detector, comprising a reference signal detector and a reflection signal detector, wherein the reference signal detector is used to detect the reference laser reflected by the polarization beam splitter and obtain a reference signal, and the reflection signal detector is used to detect the reflected laser from the sample to be tested and obtain a reflection signal;

[0008] A lock-in amplifier, the lock-in amplifier is connected to the differential detector, and the lock-in amplifier is used to perform a lock-in analysis based on the reflection signal and the reference signal to determine the temperature information of the sample to be tested;

[0009] The lock-in amplifier is connected to the optical switch, and the optical switch modulates the incident laser light according to a target modulation frequency determined by the lock-in amplifier based on the temperature information.

[0010] Optionally, the differential detector is further used to generate a temperature distribution image corresponding to the sample to be tested according to a differential signal and the temperature information, and the differential signal is obtained by the differential detector performing a differential operation on the reference signal and the reflected signal.

[0011] Optionally, the device further comprises a linear polarizer, wherein the linear polarizer is disposed between the reference signal detector and the polarization beam splitter, the direction of the linear polarizer is adjustable, and the linear polarizer is used to perform power compensation on the reference laser.

[0012] Optionally, when the reflection signal detector is a single-point detector, the device further includes a scanning module, wherein the scanning module is disposed between the polarization beam splitter and the quarter wave plate, and the scanning module is used for scanning the laser.

[0013] Optionally, the device further comprises a control unit, and the control unit is used to control the position of the scanning module and to control the modulation of the incident laser.

[0014] Optionally, the device further comprises an optical relay module, wherein the optical relay module is disposed between the scanning module and the 1 / 4 wave plate, and the optical relay module is used for laser beam expansion and aberration correction.

[0015] Optionally, the control unit is connected to the sample to be tested to synchronize time.

[0016] Optionally, the device further includes a reflector and a filtering unit, wherein the reflector and the filtering unit are arranged between the polarization beam splitter and the reflected signal detector, and the filtering unit is used for performing spatial filtering on the reflected laser.

[0017] Optionally, the device further comprises a reflector, wherein the reflector is arranged between the 1 / 4 wave plate and the objective lens of the microscope.

[0018] In a second aspect, the present application provides a temperature measurement method based on laser reflection, the method comprising:

[0019] The laser provides incident laser light of polarization state, which is modulated by an optical switch and transmitted to a polarization beam splitter;

[0020] The polarization beam splitter separates the modulated incident laser into reference laser and irradiation laser; the irradiation laser passes through a quarter wave plate and an objective lens of a microscope in sequence and then irradiates the surface of the sample to be measured, and generates reflected laser;

[0021] The polarization beam splitter reflects the reference laser to a reference signal detector in a differential detector;

[0022] The polarization beam splitter reflects the reflected laser to the reflection signal detector in the differential detector;

[0023] The reference signal detector detects the reference laser to obtain a reference signal;

[0024] The reflection signal detector detects the reflected laser to obtain a reflection signal;

[0025] The lock-in amplifier (3) performs a lock-in analysis based on the reflection signal and the reference signal to determine the temperature information of the sample to be tested (13);

[0026] The lock-in amplifier (3) determines a target modulation frequency according to the temperature information, so that the optical switch (2) modulates the incident laser according to the target modulation frequency.

[0027] Optionally, the method further includes:

[0028] The differential detector performs a differential operation on the reference signal and the reflected signal to obtain a differential signal;

[0029] The differential detector generates a temperature distribution image corresponding to the sample to be tested according to the differential signal and the temperature information.

[0030] Optionally, a scanning module is provided between the polarization beam splitter and the quarter wave plate, and the method further comprises:

[0031] When the scanning module moves to the target position specified by the control signal according to the control signal of the control center, the control center triggers the timing switch circuit to send a first time series signal and a second time series signal. The first time series signal is used to trigger the source meter to power the sample to be tested; the second time series signal is used to trigger the phase-locked amplifier to work.

[0032] The present application provides a temperature measurement device and method based on laser reflection, which has the following technical effects:

[0033] In the scheme provided by the present application, the temperature measurement device includes an optical modulation module, a differential detector and a phase-locked amplifier, the optical modulation module includes a laser and an optical switch, wherein the laser is used to output an incident laser in a polarization state, and the optical switch is used to modulate the incident laser; a polarization beam splitter, a 1 / 4 wave plate and an objective lens of a microscope are sequentially arranged along the incident light path of the modulated incident laser; the polarization beam splitter is used to separate the modulated incident laser into a reference laser and an irradiation laser, and the irradiation laser is irradiated on the surface of the sample to be measured; the differential detector includes a reference signal detector and a reflection signal detector, the reference signal detector is used to detect the reference laser reflected by the polarization beam splitter and obtain a reference signal, and the reflection signal detector is used to detect the reflected laser from the sample to be measured and obtain a reflection signal; the phase-locked amplifier is connected to the differential detector, and is used to perform phase-locked analysis based on the reflection signal and the reference signal to determine the temperature information of the sample to be measured; the phase-locked amplifier is connected to the optical switch, so that the optical switch modulates the incident laser according to the target modulation frequency determined by the phase-locked amplifier based on the temperature information.

[0034] The solution provided by the present application is based on the principle of thermal reflection to detect imaging and measure the temperature of the sample to be tested. In the solution provided by the present application, the reflected laser is efficiently obtained through a polarization beam splitter and a 1 / 4 wave plate, which can improve the resolution of imaging and reduce the thermal impact of the reflected laser on the sample to be tested; in the solution provided by the present application, a differential detector including a reference signal detector and a reflected signal detector is introduced, which can effectively reduce the impact of noise on signal detection and improve the stability and accuracy of imaging; in the solution provided by the present application, a phase-locked amplifier is used to perform phase-locked analysis on the reference signal detector and the reflected signal, which can quickly and accurately extract temperature information and improve the accuracy and speed of temperature measurement.

[0035] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 is a schematic structural diagram of a temperature measurement device based on laser reflection provided in an embodiment of the present application;

[0038] Figure 2 It is a schematic diagram of an implementation flow of a temperature measurement method based on laser reflection provided in an embodiment of the present application;

[0039] Figure 3 It is a control flow diagram of a temperature measurement method based on laser reflection provided in an embodiment of the present application;

[0040] Among them, 1-laser, 2-optical switch, 3-phase-locked amplifier, 4-reference signal detector, 5-reflection signal detector, 6-linear polarizer, 7-polarization beam splitter, 8-scanning module, 9-optical relay module, 10-1 / 4 wave plate, 11-reflector, 12-objective lens of microscope, 13-sample to be tested, 14-reflector, 15-filter unit, 16-pinhole. DETAILED DESCRIPTION

[0041] The embodiments of the present application provide a temperature measurement device and method based on laser reflection. The technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of this application. Examples of the embodiments are shown in the drawings, where the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions.

[0042] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0043] See also Figure 1 , which is a schematic diagram of the structure of a temperature measurement device based on laser reflection provided in an embodiment of the present application. Figure 1 As shown, the temperature measuring device at least includes a laser 1, an optical switch 2, a phase-locked amplifier 3, a reference signal detector 4, a reflection signal detector 5, a polarization beam splitter 7, a quarter wave plate 10, and an objective lens 12 of a microscope. The laser 1 and the optical switch 2 constitute an optical modulation module, and the reference signal detector 4 and the reflection signal detector 5 constitute a differential detector.

[0044] The laser 1 is used to output the polarized state of the incident laser, and the optical switch 2 is used to modulate the incident laser.

[0045] A polarization beam splitter 7, a quarter wave plate 10, and an objective lens 12 of a microscope are sequentially arranged along the incident optical path of the modulated incident laser light.

[0046] The polarization beam splitter 7 is used to separate the modulated incident laser into reference laser and irradiation laser, and the irradiation laser is irradiated on the surface of the sample 13 to be tested.

[0047] The reference signal detector 4 is used to detect the reference laser reflected by the polarization beam splitter 7 and obtain a reference signal.

[0048] The reflection signal detector 5 is used to detect the reflected laser from the sample to be tested 13 and obtain a reflection signal.

[0049] The lock-in amplifier 3 is connected to the differential detector, and is used to perform a lock-in analysis based on the reflection signal and the reference signal to determine the temperature information of the sample 13 to be tested.

[0050] The lock-in amplifier 3 is connected to the optical switch 2 , and the optical switch 2 modulates the incident laser light according to the target modulation frequency determined by the lock-in amplifier 3 based on the temperature information.

[0051] In one embodiment of the present application, the laser 1 may be a linearly polarized laser, and the incident laser wave generated by the linearly polarized laser vibrates along a specific direction.

[0052] In one embodiment of the present application, the illuminating laser emitted after the incident laser passes through the polarization beam splitter 7 is p-polarized light, and after passing through the 1 / 4 wave plate 10, it becomes circularly polarized light (such as right-handed circularly polarized light). The reflected laser reflected back from the sample to be tested 13 (left-handed circularly polarized light) passes through the 1 / 4 wave plate 10 and becomes s-polarized light. The s-polarized light will be reflected by the polarization beam splitter 7 and enter the reflection signal detector 5.

[0053] In one embodiment of the present application, the reference signal detector 4 and the reflection signal detector 5 have the same optical path.

[0054] In one embodiment of the present application, the surface of the sample 13 to be tested is covered with a metal layer, and the optical properties of the metal layer change with temperature, so that the surface temperature of the sample 13 to be tested can be measured according to the thermal properties of the metal layer.

[0055] In one embodiment of the present application, the microscope is a confocal microscope. Figure 1 The XYZ three-dimensional displacement platform shown can perform three-dimensional imaging of the sample 13 to be tested.

[0056] In one embodiment of the present application, during the initialization stage, the received light intensity of the reference detector 4 can also be changed by adjusting the polarizer 6 so that the output differential signal is close to zero, thereby achieving zero adjustment of the phase-locked amplifier 3, so that when the temperature changes, the phase-locked amplifier 3 can quickly and accurately determine the temperature change.

[0057] In the above embodiments, the detection imaging and temperature measurement of the sample to be tested are performed based on the principle of thermal reflection. In the scheme provided by the present application, the reflected laser is efficiently obtained through a polarization beam splitter and a 1 / 4 wave plate, which can improve the resolution of imaging and reduce the thermal impact of the reflected laser on the sample to be tested; in the scheme provided by the present application, a differential detector including a reference signal detector and a reflected signal detector is introduced, which can effectively reduce the impact of noise on signal detection and improve the stability and accuracy of imaging; in the scheme provided by the present application, a phase-locked amplifier is used to perform phase-locked analysis on the reference signal detector and the reflected signal, which can quickly and accurately extract temperature information and improve the accuracy and speed of temperature measurement.

[0058] The temperature measurement device provided by the present application can be used in various micro-nano structures such as integrated circuit manufacturing and biological tissue engineering. For example, in the production process of semiconductor devices, the system can quickly measure the temperature of the device, detect the heating process, and measure the impact of surges on the safety margin of device performance.

[0059] In one embodiment of the present application, the differential detector is also used to generate a temperature distribution image corresponding to the sample to be tested 13 according to the differential signal and the temperature information, and the differential signal is obtained by the differential detector performing a differential operation on the reference signal and the reflected signal. Performing a differential operation on the reference signal and the reflected signal can effectively reduce the influence of noise on signal detection, especially the background noise generated by the laser disturbance, and improve the stability and accuracy of imaging.

[0060] Furthermore, the lock-in amplifier 3 is used to perform lock-in analysis based on the differential signal and the reference signal to determine the temperature information of the sample to be tested 13. Using the differential signal and the reference signal to perform lock-in analysis can further improve the accuracy of the determined temperature information and reduce the influence of noise.

[0061] In one embodiment of the present application, the device further comprises a linear polarizer 6, which is disposed between the reference signal detector 4 and the polarization beam splitter 7, and the direction of the linear polarizer 6 is adjustable, and the linear polarizer 6 is used to perform power compensation on the reference laser. By using the linear polarizer 6 to perform power compensation on the reference laser, the disturbance of the laser can be further reduced, that is, by adjusting the intensity of the reference laser and the reflected laser, the laser disturbance can be removed, and the noise influence caused by the disturbance can be reduced.

[0062] In one embodiment of the present application, when the reflection signal detector 5 is a single-point detector, the device further includes a scanning module 8, which is disposed between the polarization beam splitter 7 and the quarter wave plate 10, and is used to scan the laser. That is, when the reflection signal detector 5 is a single-point detector, it does not have a spatial resolution function, and the scanning module 8 is used to scan the laser, and the reflected lasers at different positions of the sample 13 to be tested can be received by the reflection signal detector 5, so that the surface of the sample 13 to be tested can be completely imaged.

[0063] In one embodiment of the present application, the temperature measurement device further includes a control unit, which is used to control the position of the scanning module and to control the modulation of the incident laser. Preferably, the control unit may include a phase-locked amplifier 3, and the control unit controls the movement of the scanning module and sends the target modulation frequency determined by the phase-locked amplifier to the optical switch 2. Preferably, the control unit may also perform high-speed demodulation on the signal sent by the reference arm of the reference signal detector 4 and the signal sent by the reflection arm of the reflection signal detector 5 to measure more quickly.

[0064] In one embodiment of the present application, the control unit is connected to the sample to be tested 13 to synchronize time.

[0065] It is understandable that the working time information of the sample to be tested 13 may be included in the temperature distribution image to be generated. For example, some devices need to measure the temperature change at the switching moment, so the measurement time and the switching moment need to be synchronized. Specifically, when the scanning module 8 moves to the target position specified by the control signal according to the control signal of the control center, the control center triggers the timing switch circuit to send a first time series signal and a second time series signal. The first time series signal is used to trigger the source table to power the sample to be tested 13; the second time series signal is used to trigger the phase-locked amplifier 3 to work. The working time of the phase-locked amplifier 3 can be synchronized with the working time of the sample to be tested 13 through the first event sequence signal and the second time series signal. By measuring and imaging the temperature of the sample to be tested 13 for a period of time, an image or video of the temperature distribution change corresponding to the sample to be tested 13 can be obtained.

[0066] In one embodiment of the present application, the device further includes an optical relay module 9, which is disposed between the scanning module 8 and the 1 / 4 wave plate 10. The optical relay module 9 is used for laser beam expansion, and the optical relay module 9 can also be used to correct aberrations to reduce post-imaging processing. The irradiation laser output by the optical relay module 9 fills the entrance pupil of the objective lens 12 to maximize the optical resolution limit of the objective lens, thereby improving the resolution of the imaging. Furthermore, the optical relay module 9 can be a double telecentric structure, thereby reducing the distortion of the imaging.

[0067] In one embodiment of the present application, the device further includes a reflector 14 and a filter unit 15, which are arranged between the polarization beam splitter 7 and the reflection signal detector 5, and the filter unit 15 is used to perform spatial filtering on the reflected laser. The filter unit 15 may include two lenses and a pinhole 16, which may be used to block light outside the focal plane of the microscope from entering the reflection signal detector 5, such as stray light returned by the sample to be tested 13 or other optical elements.

[0068] In one embodiment of the present application, the device further comprises a reflector 11 , and the reflector 11 is disposed between the 1 / 4 wave plate 10 and the objective lens 12 of the microscope.

[0069] In a specific embodiment of the present application, the temperature measurement device includes: a laser 1, an optical switch 2, a control center, a control including a phase-locked amplifier 3, a reference signal detector 4, a reflection signal detector 5, a linear polarizer 6, a polarization beam splitter 7, a scanning module 8, an optical relay module 9, a 1 / 4 wave plate 10, a reflector 11, an objective lens 12 of a microscope, a sample to be tested 13, a reflector 14, a filter unit 15, and a pinhole 16. The surface of the sample to be tested 13 is covered with a metal layer. When the scanning module 8 moves to the target position specified by the control signal according to the control signal of the control center, the control center triggers the timing switch circuit to send a first time series signal and a second time series signal, and the first time series signal is used to trigger the source table to power the sample to be tested 13; the second time series signal is used to trigger the phase-locked amplifier 3 to work. The first event sequence signal and the second time series signal can be used to synchronize the working time of the phase-locked amplifier 3 with the working time of the sample to be tested 13. At the same time, the laser 1 outputs the incident laser in the polarization state, and the optical switch 2 modulates the incident laser. The modulation frequency is determined by the phase-locked amplifier 3 in the control center and can be adaptively adjusted according to the measured temperature information. The polarization beam splitter 7 is used to separate the modulated incident laser into the reference laser and the irradiation laser. The reference signal detector 4 is used to detect the reference laser reflected by the polarization beam splitter 7 and obtain the reference signal. The irradiation laser is scanned by the scanning module 8, expanded by the optical relay module 9, polarized by the 1 / 4 wave plate 10, and reflected by the reflector 11. It enters the objective lens 12 of the microscope and finally irradiates the surface of the sample 13 to be tested. The sample 13 to be tested generates the corresponding reflected laser. The reflected laser returns to the polarization beam splitter 7 along the original irradiation light path, and is detected by the reflection signal detector 5 and converted into a reflection signal through the reflection of the polarization beam splitter 7, the spatial filtering of the reflector 14 and the filtering unit 15. The reflected signal and the reference signal are transmitted to the phase-locked amplifier 3 of the control center for phase-locked demodulation analysis to determine the change of the laser reflectivity, and then determine the temperature change according to the change of the laser reflectivity. In addition, the phase-locked amplifier 3 can also adjust the modulation frequency of the incident laser according to the temperature change indicated by the temperature information.

[0070] See also Figure 2 , which is an implementation flow chart of a temperature measurement method based on laser reflection provided in an embodiment of the present application. The present application provides method operation steps as described in the embodiment or flow chart, but may include more or fewer operation steps based on conventional or non-creative labor. The order of steps listed in the embodiment is only one way of executing the steps among many orders, and does not represent the only order of execution. When the actual system or server product is executed, it can be executed in sequence or in parallel according to the method shown in the embodiment or the accompanying drawings (for example, in a parallel processor or multi-threaded processing environment). Please refer to Figure 2 A temperature measurement method based on laser reflection provided in an embodiment of the present application may include the following steps:

[0071] S210: Laser 1 provides incident laser light of a polarized state, which is modulated by optical switch 2 and transmitted to polarization beam splitter 7.

[0072] S220: The polarization beam splitter 7 separates the modulated incident laser into a reference laser and an irradiation laser; the irradiation laser passes through the 1 / 4 wave plate 10 and the objective lens 12 of the microscope in sequence and then irradiates the surface of the sample to be tested 13, and generates reflected laser.

[0073] In one embodiment of the present application, the irradiation laser is sequentially scanned by the scanning module 8, expanded by the optical relay module 9, irradiated on the surface of the sample 13 to be tested, after passing through the quarter wave plate 10, the reflector 11 and the objective lens 12 of the microscope.

[0074] S230: The polarization beam splitter 7 reflects the reference laser to the reference signal detector 4 in the differential detector.

[0075] In one embodiment of the present application, a linear polarizer 6 is provided between the reference signal detector 4 and the polarization beam splitter 7. The direction of the linear polarizer 6 is adjustable. By adjusting the direction, the power of the reference laser can be compensated to further reduce the disturbance of the laser. That is, by adjusting the intensity of the reference laser and the reflected laser, the laser disturbance can be removed and the noise impact caused by the disturbance can be reduced.

[0076] S240: The polarization beam splitter 7 reflects the reflected laser to the reflection signal detector 5 in the differential detector.

[0077] In one embodiment of the present application, a reflector 14 and a filter unit 15 are provided between the polarization beam splitter 7 and the reflection signal detector 5 , and the reflected laser is detected by the reflection signal detector 5 after being reflected by the reflector 14 and filtered by the filter unit 15 .

[0078] Exemplarily, the incident laser is transmitted through the polarization beam splitter 7 and the emitted illuminating laser is p-polarized light, which is circularly polarized light (such as right-handed circularly polarized light) after passing through the quarter wave plate 10. The reflected laser (left-handed circularly polarized light) reflected from the sample to be tested 13 is converted into s-polarized light after passing through the quarter wave plate 10. The s-polarized light will be reflected by the polarization beam splitter 7 and enter the reflection signal detector 5.

[0079] S250: The reference signal detector 4 detects the reference laser to obtain a reference signal.

[0080] Specifically, the reference signal detector 4 performs photoelectric conversion on the detected reference laser to obtain a reference signal.

[0081] S260: The reflection signal detector 5 detects the reflected laser to obtain a reflection signal.

[0082] Specifically, the reflection signal detector 5 performs photoelectric conversion on the detected reflected laser to obtain a reflection signal.

[0083] S270: The phase-locked amplifier 3 performs phase-locked analysis based on the reflected signal and the reference signal to determine the temperature information of the sample 13 to be tested.

[0084] S280: The lock-in amplifier 3 determines the target modulation frequency based on the temperature information, so that the optical switch (2) modulates the incident laser according to the target modulation frequency.

[0085] Specifically, the lock-in amplifier 3 can adjust the initial modulation frequency according to the temperature change indicated by the temperature information to obtain the target modulation frequency for the incident laser in the next measurement process.

[0086] Specifically, one input of the phase-locked amplifier 3 is a reflection signal containing noise. The amplitude of the effective signal in the reflection signal is relatively weak compared to the noise, so the signal-to-noise ratio of the input reflection signal is very low. The reflection signal needs to be pre-amplified first to amplify the weak effective signal to a level sufficient to promote phase-sensitive detection. At the same time, some interference and noise can be filtered out by filtering; another input of the phase-locked amplifier 3 is a reference signal, which is an electrical signal corresponding to a reference laser reflected by the polarization beam splitter 7 locked and tracked by the phase-locked loop. The reference signal can be amplified or attenuated first to meet the amplitude requirements of phase-sensitive detection, and the reference signal can be phase-locked and phase-shifted to generate sine waves and / or cosine waves of the same frequency for multiplication in the phase-sensitive detection link. In the phase-sensitive detection link, the reflected signal after amplification and filtering is multiplied with the reference signal after phase shifting to obtain DC and AC components. The DC component contains the amplitude of the effective signal, the amplitude of the reference signal, and the phase difference between the effective signal and the reference signal. When the effective signal and the reference signal are stable, the DC component is a fixed value, so the AC component containing noise information can be filtered out by a low-pass filter, leaving the DC component, and the amplitude and phase of the effective signal can be calculated.

[0087] Specifically, the changes in the amplitude and phase of the effective signal can characterize the changes in the reflection intensity, and then the phase-locked amplifier 3 determines the corresponding changes in the laser reflectivity based on the changes in the reflection intensity, and then determines the temperature changes of the sample 13 to be tested based on the temperature dependence of the light reflectivity.

[0088] In one embodiment of the present application, the method may further include:

[0089] The differential detector performs a differential operation on the reference signal and the reflected signal to obtain a differential signal;

[0090] The differential detector generates a temperature distribution image corresponding to the sample 13 to be tested according to the differential signal and the temperature information.

[0091] Specifically, the planar imaging result of the sample 13 to be tested can be determined according to the differential signal, and the temperature distribution image of the sample 13 to be tested can be obtained by superimposing the temperature information.

[0092] It can be understood that differential detection can amplify the difference between the two input signals while suppressing the common signal in the reference signal and the reflected signal, that is, the common mode noise. Described in mathematical expressions, the reference signal and the reflected signal are V in+ and V in- , the output of the differential amplifier V out It can represent:

[0093]

[0094] Among them: Ad is the differential gain (the ability to amplify the differential signal); A cm is the common-mode gain (the ability to amplify common-mode signals).

[0095] Differential probing with high differential gain A d and a near-zero common-mode gain A cm , which means that if the reference signal and the reflected signal contain the same common-mode noise V cm , then the differential output will not be affected by the common-mode noise V cm For optical signal light, most of the optical noise comes from the jitter of the laser. By using the differential principle, the jitter of the laser itself can be reduced, thereby reducing the impact of noise and improving the accuracy and efficiency of imaging.

[0096] Furthermore, the lock-in amplifier 3 performs a lock-in analysis based on the differential signal and the reference signal to determine the temperature information of the sample 13 to be tested.

[0097] In one embodiment of the present application, the method may further include:

[0098] When the scanning module 8 moves to the target position specified by the control signal according to the control signal of the control center, the control center triggers the timing switch circuit to send a first time series signal and a second time series signal. The first time series signal is used to trigger the source table to power the sample to be tested 13; the second time series signal is used to trigger the phase-locked amplifier 3 to work.

[0099] like Figure 3 As shown, the control center provides a control signal to the scanning module 8, and the control center waits for the scanning module 8 to step to the specified position. After reaching the specified position, the control center triggers the timing card (also known as the timing switch circuit). After receiving the trigger signal, the timing card sends out two time series signals, wherein the first time series signal is sent to the source meter so that the source meter powers the sample 13 to be tested. At the same time, the second time series signal is sent to the phase-locked amplifier 3 to trigger the phase-locked amplifier 3 to perform signal acquisition. The control center waits for the image acquisition of the current pixel to be completed. After the image acquisition of the current pixel is completed, the control center provides a new control signal to the scanning module to perform temperature measurement and imaging of the new pixel until all pixels of the sample 13 to be tested are fully acquired.

[0100] It should be noted that the above-mentioned sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above-mentioned specific embodiments of the present application are described. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0101] Each embodiment in this application is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device, equipment and storage medium embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0102] A person skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware or by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a disk or an optical disk, etc.

[0103] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A temperature measurement device based on laser reflection, characterized in that: The device comprises: The optical modulation module comprises a laser (1) and an optical switch (2), wherein the laser (1) is used to output incident laser light in a polarization state, and the optical switch (2) is used to modulate the incident laser light; a polarization beam splitter (7), a quarter wave plate (10), and an objective lens (12) of a microscope are sequentially arranged along the incident light path of the modulated incident laser light; the polarization beam splitter (7) is used to separate the modulated incident laser light into a reference laser light and an irradiation laser light, and the irradiation laser light is irradiated onto the surface of a sample (13) to be measured; A differential detector, comprising a reference signal detector (4) and a reflection signal detector (5), wherein the reference signal detector (4) is used to detect the reference laser reflected by the polarization beam splitter (7) and obtain a reference signal, and the reflection signal detector (5) is used to detect the reflected laser from the sample to be tested (13) and obtain a reflection signal; A lock-in amplifier (3), the lock-in amplifier (3) being connected to the differential detector, and the lock-in amplifier (3) being used to perform a lock-in analysis based on the reflection signal and the reference signal to determine the temperature information of the sample to be tested (13); The lock-in amplifier (3) is connected to the optical switch (2), and the optical switch (2) modulates the incident laser light according to a target modulation frequency determined by the lock-in amplifier (3) based on the temperature information.

2. The device according to claim 1, characterized in that The differential detector is also used to generate a temperature distribution image corresponding to the sample (13) to be tested according to the differential signal and the temperature information, and the differential signal is obtained by the differential detector performing a differential operation on the reference signal and the reflected signal.

3. The device according to claim 1, characterized in that The device further comprises a linear polarizer (6), wherein the linear polarizer (6) is arranged between the reference signal detector (4) and the polarization beam splitter (7), the direction of the linear polarizer (6) is adjustable, and the linear polarizer (6) is used to perform power compensation on the reference laser.

4. The device according to claim 1, characterized in that When the reflection signal detector (5) is a single-point detector, the device further comprises a scanning module (8), wherein the scanning module (8) is arranged between the polarization beam splitter (7) and the quarter wave plate (10), and the scanning module (8) is used to scan the irradiation laser and the reflection laser.

5. The device according to claim 4, characterized in that The device also includes a control unit, which is used to control the position of the scanning module and to control the modulation of the incident laser.

6. The device according to claim 4, characterized in that The device further comprises an optical relay module (9), wherein the optical relay module (9) is arranged between the scanning module (8) and the quarter wave plate (10), and the optical relay module (9) is used for laser beam expansion and aberration correction.

7. The device according to claim 5, characterized in that The control unit is connected to the sample to be tested (13) to synchronize time.

8. The device according to claim 1, characterized in that The device further comprises a reflector (14) and a filtering unit (15), wherein the reflector (14) and the filtering unit (15) are arranged between the polarization beam splitter (7) and the reflection signal detector (5), and the filtering unit (15) is used for spatially filtering the reflected laser.

9. A temperature measurement method based on laser reflection, characterized in that: The method comprises: The laser (1) provides incident laser light of a polarized state, which is modulated by an optical switch (2) and then transmitted to a polarization beam splitter (7); The polarization beam splitter (7) separates the modulated incident laser into reference laser and irradiation laser; the irradiation laser sequentially passes through a quarter wave plate (10) and an objective lens (12) of a microscope and then irradiates the surface of a sample to be measured (13), thereby generating reflected laser. The polarization beam splitter (7) reflects the reference laser to a reference signal detector (4) in a differential detector; The polarization beam splitter (7) reflects the reflected laser light to the reflection signal detector (5) in the differential detector; The reference signal detector (4) detects the reference laser to obtain a reference signal; The reflection signal detector (5) detects the reflected laser to obtain a reflection signal; The lock-in amplifier (3) performs a lock-in analysis based on the reflection signal and the reference signal to determine the temperature information of the sample to be tested (13); The lock-in amplifier (3) determines a target modulation frequency according to the temperature information, so that the optical switch (2) modulates the incident laser according to the target modulation frequency.

10. The method according to claim 9, characterized in that The method further comprises: The differential detector performs a differential operation on the reference signal and the reflected signal to obtain a differential signal; The differential detector generates a temperature distribution image corresponding to the sample (13) to be tested according to the differential signal and the temperature information.

11. The method according to claim 9, characterized in that A scanning module (8) is provided between the polarization beam splitter (7) and the quarter wave plate (10), and the method further comprises: When the scanning module (8) moves to the target position specified by the control signal according to the control signal of the control center, the control center triggers the timing switch circuit to send out a first time series signal and a second time series signal, wherein the first time series signal is used to trigger the source meter to supply power to the sample to be tested (13); and the second time series signal is used to trigger the lock-in amplifier (3) to operate.

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