High power laser multi-parameter measurement device based on laser interference

Abstract

The application discloses a high-power laser multi-parameter measuring device based on laser interference, and relates to the technical field of laser parameter measurement. The internal part of the measuring device comprises a radiation pressure measuring module, a light attenuation module, a light field analysis component, a reference light source component, an interference system module and a high-speed photoelectric sensor. The laser to be measured is a laser source whose parameters need to be measured. The radiation pressure measuring module is used for measuring the radiation pressure generated by the light source to be measured, and the laser power / energy value is calculated based on the radiation pressure. The light attenuation module is used for attenuating the intensity of the laser to be measured to prevent the device from being damaged. The application carries out multi-parameter measurement of laser based on the interference principle, reduces the complexity of the optical path, and guarantees the measurement accuracy by high-precision interference measurement, which is beneficial to the modular design of laser multi-parameter measurement. The device can withstand the requirements of high-energy laser measurement and is not easy to be damaged.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of laser parameter measurement, and particularly relates to a high-power laser multi-parameter measurement device based on laser interference and a data processing method. BACKGROUND

[0002] In order to meet the needs of accurate control of laser output parameters in different fields, the output characteristics of a laser need to be measured in terms of energy, frequency domain, time domain, space domain and other parameters, such as laser energy, pulse waveform, pulse width, peak power, repetition power, instantaneous power, power stability, beam diameter, divergence angle, ellipticity, transverse mode, wavelength, spectral width, and beam quality factor. Most of the existing laser parameter measurement instruments measure one or more associated laser parameters, and cannot measure multiple parameters in terms of energy, frequency domain and time domain at the same time. Moreover, the existing laser parameter measurement devices cannot simultaneously detect the energy, power, frequency domain, time domain and spatial domain characteristics of high-power pulsed or continuous laser. To obtain the parameter information of laser in different domains, multiple different measurement devices need to be used, such as a spectrometer for measuring the wavelength and spectral distribution of laser in the frequency domain, an ultrafast photoelectric detector combined with an oscilloscope for measuring the repetition frequency, pulse width and pulse stability of laser in the time domain, and an energy meter probe combined with a meter head for measuring the power / energy of laser. The existing laser multi-parameter measurement devices are composed of multiple different measurement instruments, which increases the complexity of the measurement device and cannot meet the real-time online detection requirements, especially in the quality control scene of medical laser. For the clinical application of high-power laser, such as the treatment of myopia by femtosecond laser and the treatment of skin diseases by picosecond laser, the monitoring of laser output characteristics is more stringent. Therefore, it is necessary to propose a reliable real-time monitoring system for laser output characteristics.

[0003] For example, the laser parameter measurement device with application number 200610167350.2 includes a to-be-measured light source, a reference light source, an imaging light target and an image processing device. The related parameters of the to-be-measured laser are obtained by the ratio of the gray-scale image of the diffuse reflection laser of the to-be-measured laser and the reference light source and the diffuse reflection laser spot of the reference laser. However, the parameters that can be measured by the device are limited by the hardware equipment (image acquisition card), that is, the measured parameters are limited to image-related parameters such as pulse width and frequency, and the output characteristics of the to-be-measured laser cannot be comprehensively detected.

[0004] As the application number is 201010268566.4, the laser multi-parameter real-time measuring device, the system is composed of a light splitting device, a measuring device of each parameter, a comprehensive processing device and a display device, completes the measurement of the laser to be measured in many aspects, realizes the comprehensive, efficient and real-time measurement and monitoring of the laser output characteristics, and provides a faster and more convenient measurement for the debugging and research of the laser, but the optical path structure of the device is complex and the application scene is limited, and the device cannot measure high-power laser and cannot monitor in the laser working process.

[0005] As the application number is 201921785821.5, a multi-parameter measuring device, using a laser transmission element and a variety of parameter measuring devices can realize the measurement of laser multi-parameters, effectively solve the technical problem of needing to use a variety of different devices to measure the parameter information of different domains of laser, realize the effect of saving devices and facilitating the measurement of parameter information of different domains of laser, and also suitable for high-power laser. But the device cannot monitor in real time in the laser working scene.

[0006] The beneficial effects of the present application provide a laser multi-parameter measuring device based on laser interference principle, which solves the problem of needing to use a variety of different measuring instruments to measure the parameters of different fields of laser in the prior art, and provides a measuring device capable of simultaneously measuring a plurality of parameters such as laser wavelength in frequency domain parameters, repetition frequency, pulse width, etc. in time domain parameters, spot size, beam quality factor, etc. in space domain parameters, and pulse energy in energy power. The device can simultaneously measure the frequency domain, time domain, space domain, energy / power and the parameters calculated from the above results of high-power laser, realize more comprehensive and convenient monitoring of the output characteristics of laser beam, and will not affect the normal use of laser. SUMMARY

[0007] To solve the above technical problems, the present application is realized by the following technical scheme:

[0008] The high-power laser multi-parameter measuring device based on laser interference of the present application comprises a radiation pressure measuring module, an optical attenuation module, an optical field analysis assembly, a reference light source assembly, an interference system module and a high-speed photoelectric detector in the inside of the measuring device.

[0009] Radiation pressure measuring module: used for measuring the radiation pressure generated by the to-be-measured light source, and calculating the laser power / energy value according to the radiation pressure;

[0010] Optical attenuation module: used for attenuating the intensity of the to-be-measured laser to prevent damage to the device;

[0011] Optical field analysis assembly: used for analyzing the laser optical field and obtaining the space domain related parameters of the laser;

[0012] Interference system: the generation of interference signals of the displacement of the mirror for laser radiation pressure;

[0013] Reference light source assembly: used for emitting laser combined with the interference system to measure the displacement of the high reflector under the action of the radiation pressure generated by the measured laser, and further obtain the laser radiation pressure;

[0014] High-speed photoelectric detector: used for processing the interference signals in time domain and frequency domain to obtain the time domain and frequency domain parameters of the laser.

[0015] Further, the radiation pressure measuring module is used for completing the measurement of the laser power / energy of the to-be-measured laser, comprising an anti-interference shell, a lens light window, a high reflector and an elastic element connected with the high reflector, wherein the high reflector is fixed on the elastic element.

[0016] Further, the high reflector is used for reducing the thermal radiation effect of the laser.

[0017] Further, the light attenuation module is used for attenuating the intensity of the to-be-measured laser to avoid the damage of the measuring element; the light attenuation module is connected with a second beam splitter, and the light attenuation module is connected with a third beam splitter.

[0018] Further, the light field analysis assembly is composed of a beam sampler, a first beam absorption module, a second beam absorption module and a CCD sensor, and is used for measuring the spatial domain parameters of the to-be-measured laser.

[0019] Further, the CCD sensor is used for completing the measurement of the spatial domain parameters of the to-be-measured laser, the output end of the beam sampler is connected with the input end of the CCD sensor, and the output end of the CCD sensor is connected with an upper computer.

[0020] Further, the reference light source assembly is composed of a He-Ne laser and an optical isolator, and is used for emitting laser combined with the interference system to measure the displacement of the high reflector under the action of the radiation pressure generated by the measured laser, and further obtain the laser radiation pressure.

[0021] Further, the optical isolator is used for isolating the reflected light from being reflected back to the He-Ne laser, and the optical isolator is connected with the output end of the He-Ne laser.

[0022] Further, the high-speed photoelectric detector is used for detecting the interference signals generated by the interference part to complete the measurement of the time domain and frequency domain parameters of the to-be-measured laser.

[0023] The present application has the following beneficial effects compared with the prior art:

[0024] 1. The present application is based on the interference principle to measure the multiple parameters of the laser, reduces the complexity of the optical path, and the high-precision interference measurement can ensure the measurement accuracy, which is beneficial to the modular design of the laser multiple parameter measurement.

[0025] 2、Benefit in the device in the sampler and light attenuation module, the device can withstand the requirement of high energy laser measurement, not easy to damage.

[0026] 3、The application can monitor the laser in real time while the laser is working normally when measuring the laser to be measured.

[0027] Of course, any product implementing the present application does not necessarily need to achieve all the advantages described above at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0029] Figure 1 The measurement logic flowchart of the present application;

[0030] Figure 2 The optical path schematic diagram of the laser multi-parameter measurement device provided by the embodiment of the present application.

[0031] Among them, 1, laser to be measured; 2, radiation pressure measurement module; 3, first beam splitter; 4, first beam absorption module; 5, second beam splitter; 6, beam sampler; 7, second beam absorption module; 8, CCD sensor; 9, light attenuation module; 10, third beam splitter; 11, optical isolator; 12, He-Ne laser; 13, high-speed photodetector; 14, fourth beam splitter; 15, first mirror; 16, upper computer signal processing system. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0033] The high-power laser multi-parameter measurement device based on laser interference of the present application, the inside of the measurement device contains a radiation pressure measurement module 2, a light attenuation module 9, a light field analysis component, a reference light source component, an interference system module and a high-speed photodetector 13;

[0034] Radiation pressure measurement module 2: used for measuring the radiation pressure generated by the light source to be measured, and calculating the laser power / energy value;

[0035] Light attenuation module 9: for attenuating the intensity of the laser to be measured 1 to avoid damage to the device;

[0036] Optical field analysis component: for analysis of the laser light field, obtaining the spatial correlation parameters of the laser;

[0037] Interference system: for generating an interference signal of the displacement of the mirror under the pressure of the laser radiation;

[0038] Reference light source component: for emitting laser light combined with the interference system to measure the displacement of the highly reflective mirror under the radiation pressure generated by the laser to be measured, and then obtain the laser radiation pressure;

[0039] High-speed photodetector 13: for processing the interference signal in time domain and frequency domain to obtain the time domain and frequency domain parameters of the laser.

[0040] Preferably, the radiation pressure measurement module 2 is used to complete the measurement of the laser power / energy of the laser to be measured 1, including: an anti-interference shell, a lens light window, a highly reflective mirror and an elastic element connected thereto, wherein the highly reflective mirror is fixed on the elastic element.

[0041] Preferably, the highly reflective mirror is used to reduce the thermal radiation effect of the laser, and its reflectivity should be as high as possible. Considering the limitation of the material, a right-angle prism can be used instead of the highly reflective mirror, which can achieve total reflection of the laser, maximize the reduction of the thermal radiation effect of the laser, and reduce the uncertainty of the measurement.

[0042] Preferably, the light attenuation module 9 is used to attenuate the intensity of the laser to be measured 1 to avoid damage to the measurement element; the light attenuation module 9 is connected with the second beam splitter 5, and the light attenuation module 9 is connected with the third beam splitter 10, which is connected with the first input end of the third beam splitter 10 and the output end of the second beam splitter 5.

[0043] Preferably, the optical field analysis component is composed of a beam sampler 6, a first beam absorption module 4, a second beam absorption module 7 and a CCD sensor 8, which is used to measure the spatial parameters of the laser to be measured 1. One side of the first beam absorption module 4 is provided with a first beam splitter 3, the output end of the first beam splitter 3 is connected with the input end of the first beam absorption module 4, and the input end of the first beam splitter 3 is connected with the input end of the second beam splitter 5.

[0044] Preferably, the CCD sensor 8 is used to complete the measurement of the spatial parameters of the laser to be measured 1, and the output end of the beam sampler 6 is connected with the input end of the CCD sensor 8; the output end of the CCD sensor 8 is connected with an upper computer.

[0045] Preferably, the reference light source assembly is composed of a He-Ne laser 12 and an optical isolator 11, which is used to emit laser light combined with an interference system to measure the displacement of the high reflector under the radiation pressure of the measured laser, and then obtain the laser radiation pressure.

[0046] Preferably, the optical isolator 11 is used to isolate the reflected light back to the He-Ne laser 12, which is connected with the output end of the He-Ne laser 12 and also connected with the second input end of the third beam splitter 10. The third beam splitter 10 is provided with a fourth beam splitter 14 on one side. The output end of the third beam splitter 10 is connected with the first input end of the fourth beam splitter 14. The first output end of the fourth beam splitter 14 is connected with the input end of the first reflector 15. The second output end of the fourth beam splitter 14 is connected with the input end of the high-speed photodetector 13. The output end of the first reflector 15 is connected with the second input end of the fourth beam splitter 14.

[0047] Preferably, the high-speed photodetector 13 is used to detect the interference signal generated by the interference part to complete the measurement of the time domain and frequency domain parameters of the measured laser 1. The third beam splitter 10 is provided with the first reflector 15 on one side. The output end of the third beam splitter 10 is connected with the input end of the first reflector 15. The output end of the first reflector 15 is connected with the input end of the high-speed photodetector 13. One side of the high-speed photodetector 13 is provided with the upper computer signal processing system 16. The output end of the high-speed photodetector 13 is connected with the input end of the upper computer signal processing system 16. The He-Ne laser 12, the third beam splitter 10, the fourth beam splitter 14 and the first reflector 15 form an interference system.

[0048] As shown in Figure 1 The measurement process of the present application is as follows: a small amount of measured laser 1 is obtained by the light beam sampling system to avoid damage to the device elements by high-power laser; the measurement device mainly refers to the above-mentioned interference system, the above-mentioned high-speed photodetector 13 and the above-mentioned CCD sensor 8; after processing and display by the upper computer, the energy parameter, the time domain parameter, the spatial parameter and the frequency domain parameter are obtained.

[0049] The measurement principle of each parameter is as follows:

[0050] 1. Laser power / energy measurement: the measured laser beam first enters the radiation pressure measurement module 2 to measure the output energy or instantaneous power of the laser. The laser radiation pressure is converted into displacement through an elastic element, and then the displacement is measured by the interferometer system. The linear relationship between the displacement and the radiation pressure is established by the elastic equation as follows:

[0051] F = K·X

[0052] F is the radiation pressure of the laser on the mirror, K is the elastic modulus of the elastic element in the radiation pressure measuring module, and x is the displacement of the mirror after the action of F on the elastic modulus. The displacement is measured by the interference system. The radiation pressure is calculated by the displacement, and the laser power P is obtained by bringing the radiation pressure F into the following formula:

[0053]

[0054] 2. Time domain parameters: laser pulse width and repetition frequency measurement:

[0055] The photoelectric detector is preferably a high-speed photoelectric detector 13, and the interference signal of the laser radiation pressure is collected by a high-speed signal collection system, and the repetition frequency of the laser can be obtained by simple time domain to frequency domain conversion signal analysis; the pulse width can be determined by time domain analysis of the collected signal;

[0056] 3. Frequency domain parameters: laser wavelength measurement:

[0057] The time domain analysis is performed on the interference signal in the interference system, and the level of the interference fringes changes under the condition that the optical path difference in the interference system is unchanged,

[0058]

[0059] λ is the measured laser wavelength, nl is the optical path difference of the interferometer, and N is the interference order. We prefer a reference laser wavelength, that is, the center of the measured laser wavelength range, and the absolute difference between the measured laser wavelength and the reference wavelength is not more than half of the reference wavelength, so that the measured laser wavelength can be analyzed within a maximum and minimum intensity range. When measuring the measured laser wavelength, the interference system can be adjusted to a fixed position, such as the position of optical interference constructive or destructive, the reference laser is turned off, and the measured laser is turned on. The time domain signal intensity analysis of the high-speed photoelectric detector 13 obtains the wavelength of the measured laser;

[0060] 4. Spatial domain parameters: laser light field analysis:

[0061] The measured laser is attenuated into the light field analysis system, and the spot size, contour, laser beam quality, wavefront distribution and other related parameters are obtained through image pixel analysis;

[0062] By using the radiation pressure measuring module 2, the optical lens, the light field analysis module, the high-speed photoelectric detector 13 and the reference laser source, the measurement of multiple parameters in different domains of the laser can be realized, and the technical limitation of the prior art that multiple measuring instruments are required to measure different domain parameters of the laser is effectively solved, and the effect of accurately measuring different domain parameters of the laser on the basis of saving devices is realized.

[0063] To realize Figure 1 The functions are described in detail.Figure 2 The device provided by the embodiment of the application comprises 1, a laser to be measured; 2, a radiation pressure measurement module; 3, a first beam splitter; 4, a first beam absorption module; 5, a second beam splitter; 6, a beam sampler; 7, a second beam absorption module; 8, a CCD sensor; 9, a light attenuation module; 10, a third beam splitter; 11, an optical isolator; 12, a He-Ne laser; 13, a high-speed photodetector; 14, a fourth beam splitter; 15, a first mirror; and 16, an upper computer signal processing system.

[0064] The arrow is the transmission direction of the laser beam. When the high-power laser is incident to the radiation pressure measurement module 2, the laser is incident to the high reflector through the lens window of the shell. The laser photons are reflected on the high reflector, the momentum of the photons changes to generate radiation pressure, the radiation pressure acts on the high reflector, and the elastic element is deformed under the light pressure. Because the high reflector is fixed on the elastic element, the high reflector is micro-displaced. The interferometer composed of the first mirror 15, the high reflector and the fourth beam splitter 14 and the high-speed photodetector 13 can accurately measure the micro-displacement value of the high reflector, and the laser power / energy can be obtained after the displacement value is calculated. At the same time, the high-speed photodetector 13 records the intensity change of the interference signal, and the laser pulse width and repetition frequency can be obtained through the frequency domain analysis of the time-frequency signal, and the laser energy (power), time domain and frequency domain information such as pulse width, pulse frequency and laser wavelength are obtained.

[0065] The laser to be measured 1 is reflected by the high reflector, and is emitted from another lens window of the shell to the first beam splitter 3. The main beam is emitted from the measurement light path to the first beam absorption module 4 to be absorbed at the first beam splitter 3. Another part of the reflected light proceeds to the second beam splitter 5 along the measurement light path, and is divided into two paths. One path passes through the beam sampler 6, and then enters the second beam absorption module 7 to be absorbed. A small amount of sampling light enters the CCD sensor 8. After the sensor collects data, the data is transmitted to the upper computer for processing, and the spatial domain parameters of the laser such as spot diameter, spatial distribution and beam quality can be obtained, so that the acquisition and analysis of the laser spatial domain information are realized.

[0066] The other light passes through the light attenuation system 8, reaches the third beam splitter 10, and then enters the interferometer composed of the first mirror 15, the high reflector and the fourth beam splitter 14 and the high-speed photodetector 13. The time-frequency characteristics of the interference signal can be analyzed, and the laser pulse width and repetition frequency can be obtained through the frequency domain analysis of the time-frequency signal. The laser wavelength information is calculated, the measurement result is integrated and output to the signal processing system 16 of the host computer for processing and display, so that the output characteristics of the laser can be monitored in real time. Considering the influence of the peak power of the high-power laser on the measuring element, in the embodiment, the high-reflective mirror can be replaced by a right-angle prism, which can realize total reflection of the high-power laser, and the rest of the measurement process is consistent with the above measurement process. The input end laser power of the second beam splitter 5 is 5%-10% of the input end laser power of the first beam splitter 3, the input end laser power of the beam sampler 6 is 5%-10% of the input end laser power of the third beam splitter 10, and the input end laser power of the CCD sensor is about 1% of the input end laser power of the beam sampler 6.

[0067] In order to avoid the damage of the output signal of the third output end of the above-mentioned light attenuation element to other elements, the third output end of the first beam splitter 3 is connected with the first beam absorption module 4, and the third output end of the beam sampler 6 is connected with the second beam absorption module 7, wherein the first beam absorption module 4 can be replaced by a working target of the laser to realize online measurement of the laser working.

[0068] The laser multi-parameter measurement device provided by the application greatly reduces the operation complexity and cost by using an interference system to realize real-time measurement of the laser multi-parameters, rather than using a plurality of different instruments to realize measurement. The laser multi-parameter measurement device mentioned in the embodiment can simultaneously measure a plurality of laser parameter characteristics of high-power laser or ultra-short pulse, including laser energy / power, frequency characteristics: wavelength, time domain characteristics: pulse width, repetition frequency, and spatial domain characteristics: spot diameter. In addition to the above-mentioned plurality of parameters, the application can also measure other parameters of the laser, such as waveform, beam quality factor, power stability, etc.

[0069] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details, nor limit the application to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of the specification. The embodiments are selected and described in detail in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application. The application is limited by the claims and their entire scope and equivalents.

Claims

1. A high power laser multi-parameter measuring device based on laser interference, characterized in that, The internal part of the measuring device comprises a radiation pressure measuring module, a light attenuation module, a light field analysis assembly, a reference light source assembly, an interference system module and a high-speed photoelectric detector; The radiation pressure measuring module is used for measuring the radiation pressure generated by the to-be-measured light source and calculating the laser power / energy value, and comprises an anti-interference shell, a lens light window, a high reflector and an elastic element connected with the high reflector, wherein the high reflector is fixed on the elastic element; the high reflector is used for reducing the thermal radiation effect of the laser; The light attenuation module is used for attenuating the intensity of the to-be-measured laser to prevent damage to the device, and is connected with a second beam splitter and a third beam splitter; The light field analysis assembly is used for analyzing the laser light field and obtaining the spatial correlation parameters of the laser; the light field analysis assembly comprises a beam sampler, a first beam absorption module, a second beam absorption module and a CCD sensor; The interference system module is used for generating the interference signal of the mirror displacement formed by the laser radiation pressure; the interference system module comprises a He-Ne laser, a third beam splitter, a fourth beam splitter and a first reflector; one side of the third beam splitter is provided with the first reflector, the output end of the third beam splitter is connected with the input end of the first reflector, the output end of the first reflector is connected with the input end of the high-speed photoelectric detector, one side of the high-speed photoelectric detector is provided with an upper computer signal processing system, and the output end of the high-speed photoelectric detector is connected with the input end of the upper computer signal processing system; The reference light source assembly comprises a He-Ne laser and an optical isolator, is used for emitting laser combined with the interference system module, measuring the displacement of the high reflector under the action of the radiation pressure generated by the to-be-measured laser, and then obtaining the laser radiation pressure; The high-speed photoelectric detector is used for detecting the interference signal generated by the interference system module and completing the measurement of the time domain and frequency domain parameters of the to-be-measured laser.

2. The high power laser multi-parameter measurement device based on laser interference according to claim 1, characterized in that, The CCD sensor is used for completing the measurement of the spatial domain parameters of the to-be-measured laser; the output end of the beam sampler is connected with the input end of the CCD sensor; and the output end of the CCD sensor is connected with the upper computer signal processing system.

3. The high power laser multi-parameter measurement device based on laser interference according to claim 1, characterized in that, The optical isolator is used for isolating the reflected light from being reflected back to the He-Ne laser, and is connected with the output end of the He-Ne laser.

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