A method and device for stably splitting a laser beam, and a method and device for calibrating a laser power meter
By dividing the high-power fiber laser beam into two beams in a specific proportion and synchronous dual sampling technology, the spectral inaccuracy caused by the polarization randomness of high-power fiber lasers is solved, and the accurate calibration and on-site monitoring of the laser power meter are achieved, reducing the cost of optical components.
Patent Information
- Application Number
- CN202210546483.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-05-19
- Publication Date
- 2025-07-04
- Estimated Expiration
- 2042-05-19
AI Technical Summary
The prior art cannot effectively solve the problem of inaccurate laser power measurement caused by the random polarization direction of high-power fiber lasers, especially when high-power laser beam splitting, the polarization dependence of the dielectric film spectrometer leads to uncertain power magnitude, making it difficult to achieve accurate calibration of high-power laser power meter.
A laser beam stabilization spectroscopy method is adopted to divide the laser beam into two beams in the ratio of n:% and (1-n)%, and n:% and (1-n)% of the original beam are synchronized through a beam-combining mirror to ensure the accuracy of spectroscopy. Combined with synchronous dual sampling technology, sampling and standard laser power meter readings are used to achieve the calibration of the laser power meter by fitting functional relationship.
Accurate spectroscopy of fiber laser with unstable polarization is achieved, eliminating the influence of random polarization states of fiber laser on spectroscopy, ensuring accurate calibration and on-site monitoring of laser power meter, and reducing the cost requirements of optical components.
Smart Images
Figure CN114838817B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for stably splitting a laser beam, a device thereof, a method for calibrating a laser power meter, and a device thereof, belonging to the technical field of laser beam splitting and laser power meter calibration. Background Art
[0002] High-power fiber lasers with output powers of dozens of watts, hundreds of watts, thousands of watts, or even tens of thousands of watts have been mass-produced and applied to industrial production practices. The output powers of these high-power fiber lasers that have penetrated into all walks of life in industrial production must be frequently measured and monitored using a laser power meter.
[0003] In order to ensure accurate measurement and monitoring of the output power of the laser, it is necessary to regularly calibrate and numerically correct these power meters used in industrial production sites, which requires the development of calibration equipment for high-precision and high-stability laser power meters.
[0004] To calibrate a laser power of up to several kilowatts or even tens of thousands of watts, first, a stable high-power fiber laser light source at the instrument level is required. However, there is no high-power fiber laser with very stable various physical parameters that meets the use of test instruments. Because usually, the polarization direction of the laser beam output by a high-power fiber laser is randomly variable and uncertain, and most of the beam splitters suitable for high-power laser beam splitting are dielectric film beam splitters, and dielectric film beam splitters are polarization-dependent. Therefore, the magnitude of the power of the split laser beam has serious randomness and uncertainty, which brings great difficulties to the development of high-power laser test instruments, resulting in the inability to calibrate the power meter using a high-power fiber laser. So far, there is no effective solution to stably and reliably split a fiber laser with random polarization, nor is there any relevant report on using a fiber laser with random polarization for high-power laser power meter calibration. Summary of the Invention
[0005] The present invention provides a method for stably splitting a laser beam, a device thereof, a method for calibrating a laser power meter, and a device thereof, which can stably and accurately split laser beams of various energy levels, and can turn a high-power fiber laser beam with a random polarization direction into a completely controllable laser light source, achieving the purpose of calibrating a high-power laser power meter and on-site monitoring using a high-power fiber laser beam.
[0006] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:
[0007] A method for stably splitting a laser beam includes the following steps:
[0008] 1) Divide the laser beam It into a first beam Ia and a second beam Ib, where It, Ia, and Ib represent the light intensities of the corresponding beams respectively, and It = Ia + Ib;
[0009] 2) Divide the first beam Ia into a first A beam n%Ia and a first B beam (100 - n)%Ia; divide the second beam Ib into a second A beam n%Ib and a second B beam (100 - n)%Ib;
[0010] 3) Combine the first A beam n%Ia and the second A beam n%Ib to obtain n%It; combine the first B beam (100 - n)%Ia and the second B beam (100 - n)%Ib to obtain (100 - n)%It; achieving stable splitting of the laser beam.
[0011] In step 1), due to the randomness of the polarization direction of the light output by the fiber laser itself, the intensities of the two split beams are not the same. Moreover, as the polarization direction of the laser changes, the intensities of the two beams also change, fluctuating. Sometimes the first beam Ia is stronger, and sometimes the second beam Ib is stronger. That is, although the laser power output from the fiber laser may be relatively stable, due to the uncertainty of its polarization direction, the intensities of the two split beams are fluctuating and uncertain. Therefore, in steps 2 - 3), the first beam Ia and the second beam Ib are respectively split according to the ratio of n:(1 - n). n% of the laser power is extracted from each of these two beams, while the remaining (1 - n)% of the light energy is extracted separately. The combination of the first A beam n%Ia and the second A beam n%Ib is n% of the entire laser beam, and the combination of the first B beam (100 - n)%Ia and the second B beam (100 - n)%Ib is (1 - n)% of the entire laser beam, fundamentally ensuring the accuracy of beam splitting and avoiding the problem of inaccurate beam splitting caused by the randomness and uncertainty of the polarization direction of light.
[0012] Through the above method, precise splitting of the fiber laser with unstable polarization is achieved. The influence of the uncertainty and randomness of the polarization state of the fiber laser on beam splitting is eliminated. Regardless of how the polarization direction of the fiber laser changes, the laser beam can always be split in real time and accurately according to a specific ratio.
[0013] To reduce costs, in step 1), first expand the laser beam It and then divide it into the first beam Ia and the second beam Ib. The purpose of beam expansion is to reduce the power density of the laser beam to lower the quality requirements for subsequent optical components.
[0014] For the convenience of layout, in step 1), the laser beam It is divided into a first beam Ia and a second beam Ib that are perpendicular to each other; in step 2), the first beam Ia is divided into a first A beam n%Ia and a first B beam (100 - n)%Ia that are perpendicular to each other; the second beam Ib is divided into a second A beam n%Ib and a second B beam (100 - n)%Ib that are perpendicular to each other.
[0015] A method for calibrating a laser power meter using the above-mentioned stable beam splitting method of a laser beam includes the following steps:
[0016] First, simultaneously detect n%It using a sampling laser power meter and detect (100 - n)%It using a standard laser power meter (that is, detecting n%It using a sampling laser power meter and detecting (100 - n)%It using a standard laser power meter are carried out simultaneously, and the following similar expressions have similar meanings), and fit the readings of the sampling laser power meter and the standard laser power meter obtained to obtain the functional relationship f1 between the readings of the sampling laser power meter and the standard laser power meter;
[0017] Second, simultaneously detect n%It using a sampling laser power meter and detect (100 - n)%It using a laser power meter to be measured, and fit the readings of the sampling laser power meter and the laser power meter to be measured obtained to obtain the functional relationship f2 between the readings of the sampling laser power meter and the laser power meter to be measured;
[0018] Finally, through the conversion of f1 and f2, the functional relationship f3 between the readings of the laser power meter to be measured and the standard laser power meter is obtained, and the calibration of the standard laser power meter is realized using the functional relationship f3. In practical applications, according to any reading value of the laser power meter to be measured, the reading value of the standard laser power meter can be inverted.
[0019] A stable beam splitting device for a laser beam includes a first polarization beam splitter, a second polarization beam splitter, a first reflector, a first polarization beam combiner, a third polarization beam splitter, a second reflector, and a second polarization beam combiner;
[0020] Along the propagation directions of the reflection optical path of the first polarization beam splitter and the transmission optical path of the second polarization beam splitter, the first polarization beam splitter, the second polarization beam splitter, the first reflector, and the first polarization beam combiner are arranged in sequence;
[0021] Along the propagation directions of the reflection optical path of the first polarization beam splitter and the reflection optical path of the second polarization beam splitter, the first polarization beam splitter, the second polarization beam splitter, the second reflector, and the second polarization beam combiner are arranged in sequence;
[0022] Along the propagation directions of the transmission optical path of the first polarization beam splitter and the reflection optical path of the third polarization beam splitter, the first polarization beam splitter, the third polarization beam splitter and the first polarization beam combiner are arranged in sequence.
[0023] Along the propagation directions of the transmission optical path of the first polarization beam splitter and the transmission optical path of the third polarization beam splitter, the first polarization beam splitter, the third polarization beam splitter and the second polarization beam combiner are arranged in sequence.
[0024] In order to reduce costs, the above-mentioned stable beam splitting device for laser beams further includes a beam expander. Along the optical path propagation direction, the beam expander is arranged upstream of the first polarization beam splitter. The direction from upstream to downstream is consistent with the optical path propagation direction.
[0025] The splitting ratios of the above-mentioned second polarization beam splitter and the third polarization beam splitter are the same.
[0026] The splitting ratio of the above-mentioned first polarization beam splitter is 1:1. Of course, other splitting ratios can also be used.
[0027] The beam splitting method using the above-mentioned stable beam splitting device for laser beams includes the following steps:
[0028] 1) The laser beam It emitted by the high-power fiber laser is split by the first polarization beam splitter into a first beam Ia and a second beam Ib that are perpendicular to each other. Among them, It, Ia, and Ib respectively represent the light intensities of the corresponding beams, and It = Ia + Ib;
[0029] 2) After the first beam Ia passes through the third polarization beam splitter, it is split into a first A beam n%Ia and a first B beam (100 - n)%Ia that are perpendicular to each other; after the second beam Ib passes through the second polarization beam splitter, it is split into a second A beam n%Ib and a second B beam (100 - n)%Ib that are perpendicular to each other;
[0030] 3) The first A beam n%Ia and the second A beam n%Ib reflected by the first reflector are combined by the first polarization beam combiner to obtain n%(Ia + Ib) = n%It; the first B beam (100 - n)%Ia and the second B beam (100 - n)%Ib reflected by the second reflector are combined by the second polarization beam combiner to obtain (100 - n)%(Ia + Ib) = (100 - n)%It, completing the stable beam splitting of the laser beam.
[0031] Preferably, in the above step 1), the laser beam It emitted by the high-power fiber laser is expanded by the beam expander and then split by the first polarization beam splitter into a first beam Ia and a second beam Ib that are perpendicular to each other.
[0032] Generally, any physical quantity is a function of time and constantly fluctuates with time. The output power of a fiber laser is no exception. If the fiber laser is directly used to first measure the reading of a standard laser power meter and then measure the reading of the laser power meter to be tested, due to the different times of the two measurements, an error is introduced due to the fluctuation of the laser output power. Therefore, the power meter cannot be simply calibrated by comparing the two measurement values. As described above, our solution divides the fiber laser with random polarization into two beams of light with a certain ratio. One beam is the sampling beam n%It, and the other beam is the measurement beam (100 - n)%It. We further adopt the method of synchronous dual sampling to simultaneously read the values of the sampling beam and the measurement beam, eliminating the time fluctuation error of the laser output.
[0033] A device for applying an industrial fiber laser to calibrate a laser power meter, comprising a first polarization beam splitter, a second polarization beam splitter, a first reflector, a first polarization beam combiner, a third polarization beam splitter, a second reflector, a second polarization beam combiner, a first laser power meter and a second laser power meter; the first laser power meter is a sampling laser power meter, and the second laser power meter is a laser power meter to be tested or a standard laser power meter;
[0034] Along the propagation direction of the reflected light path of the first polarization beam splitter and the transmitted light path of the second polarization beam splitter, the first polarization beam splitter, the second polarization beam splitter, the first reflector, the first polarization beam combiner and the first laser power meter are sequentially arranged;
[0035] Along the propagation direction of the reflected light path of the first polarization beam splitter and the reflected light path of the second polarization beam splitter, the first polarization beam splitter, the second polarization beam splitter, the second reflector, the second polarization beam combiner and the second laser power meter are sequentially arranged;
[0036] Along the propagation direction of the transmitted light path of the first polarization beam splitter and the reflected light path of the third polarization beam splitter, the first polarization beam splitter, the third polarization beam splitter, the first polarization beam combiner and the first laser power meter are sequentially arranged;
[0037] Along the propagation direction of the transmitted light path of the first polarization beam splitter and the transmitted light path of the third polarization beam splitter, the first polarization beam splitter, the third polarization beam splitter, the second polarization beam combiner and the second laser power meter are sequentially arranged.
[0038] To reduce costs, the above device further includes a beam expander, which is arranged upstream of the first polarization beam splitter along the light path propagation direction.
[0039] The splitting ratios of the above second polarization beam splitter and the third polarization beam splitter are the same.
[0040] Install a sampling laser power meter on the sampling optical path, and install a laser power meter under test or a standard laser power meter on the test optical path to simultaneously read the powers of two lasers, eliminating the variation in the readings of the two optical paths caused by time.
[0041] To facilitate reading, the device for calibrating a laser power meter by applying an industrial-grade fiber laser further includes a sampler. Both the first laser power meter and the second laser power meter are connected to the sampler and transmit data to the sampler simultaneously.
[0042] A method for calibrating a laser power meter using the device for calibrating a laser power meter by applying an industrial-grade fiber laser includes the following steps:
[0043] 1) The laser beam of the high-power fiber laser is divided by the first polarization beam splitter into a first beam Ia and a second beam Ib that are perpendicular to each other. Here, It, Ia, and Ib represent the light intensities of the corresponding beams, and It = Ia + Ib;
[0044] 2) After the first beam Ia passes through the third polarization beam splitter, it is divided into a first A beam n%Ia and a first B beam (100 - n)%Ia that are perpendicular to each other; after the second beam Ib passes through the second polarization beam splitter, it is divided into a second A beam n%Ib and a second B beam (100 - n)%Ib that are perpendicular to each other;
[0045] 3) The first A beam n%Ia and the second A beam n%Ib reflected by the first mirror are combined by the first polarization beam combiner to obtain n%(Ia + Ib) = n%It, which is detected by the first laser power meter; the first B beam (100 - n)%Ia and the second B beam (100 - n)%Ib reflected by the second mirror are combined by the second polarization beam combiner to obtain (100 - n)%(Ia + Ib) = (100 - n)%It, which is detected by the second laser power meter. The first laser power meter is the sampling laser power meter, and the second laser power meter is the laser power meter under test or the standard laser power meter. The specific process is as follows:
[0046] First, install the standard laser power meter, and simultaneously obtain the readings of the sampling laser power meter and the standard laser power meter by means of double sampling, and fit to obtain the functional relationship f1 between the readings of the sampling laser power meter and the standard laser power meter;
[0047] Second, replace the standard laser power meter with the laser power meter under test, and also simultaneously obtain the readings of the sampling laser power meter and the laser power meter under test by means of double sampling, and fit to obtain the functional relationship f2 between the readings of the sampling laser power meter and the laser power meter under test;
[0048] Finally, through the conversion of f1 and f2, the functional relationship f3 between the readings of the laser power meter to be measured and the readings of the standard laser power meter is obtained, and the calibration of the standard laser power meter is achieved by using f3. In practical applications, according to any reading value of the laser power meter to be measured, the reading value of the standard laser power meter can be inverted.
[0049] In the above step 1), the laser beam It is first expanded and then divided into a first beam Ia and a second beam Ib. The purpose of beam expansion is to reduce the power density of the laser beam to reduce the quality requirements for subsequent optical elements.
[0050] In the above step 3), the sampler simultaneously reads the readings of the first laser power meter (sampling laser power meter) and the second laser power meter (laser power meter to be measured or standard laser power meter).
[0051] In the above step 3), no matter how unstable the relative intensities of the two split beams Ia and Ib are due to the uncertainty of laser polarization, the optical power detected by the first laser power meter is n% of the total laser output power, which is certain; and the optical power detected by the second laser power meter is (100 - n)% of the total laser output power, which is also a certain value.
[0052] The laser output power sometimes shows large fluctuations over time, which also affects the accuracy of the measuring instrument. In this application, a simultaneous dual-sampling scheme is further proposed to eliminate the influence of the time fluctuation of the laser output on the accuracy of the test instrument.
[0053] For different types of lasers, the numerical definition of high power is different. Usually, a fiber laser power greater than 100W is considered high power.
[0054] Technologies not mentioned in the present invention shall refer to the prior art.
[0055] The stable beam splitting method and device for the laser beam of the present invention can stably and accurately split the laser beams of each energy level, including high-power fiber laser beams with random polarization directions, completely eliminating the problem that it is difficult to split the intensity according to a precise ratio due to the random polarization direction of high-power fiber laser beams, etc.; achieving the purpose of calibrating high-power laser power meters and on-site monitoring using high-power fiber laser beams. Further, by using the method of simultaneously reading the values of the sampling beam and the measurement beam, the time fluctuation error of the laser output is eliminated. BRIEF DESCRIPTION OF THE DRAWINGS
[0056] Figure 1 is the optical path structure diagram of applying an industrial fiber laser to the calibration of a laser power meter in the present invention (the part of the optical path structure of the stable beam splitting device for the laser beam is in the dotted box in the figure);
[0057] Figure 2 This is a structural schematic diagram of the device for applying an industrial fiber laser to calibrate a laser power meter according to the present invention;
[0058] Figure 3 It is the functional relationship f1 between the readings of the sampling laser power meter and the standard laser power meter in Example 2;
[0059] Figure 4 It is the functional relationship f2 between the readings of the sampling laser power meter and the laser power meter to be measured in Example 2;
[0060] Figure 5 It is the functional relationship f3 between the readings of the laser power meter to be measured and the standard laser power meter in Example 2;
[0061] In the figure, 1 is the first polarization beam splitter, 2 is the second polarization beam splitter, 3 is the first reflector, 4 is the first polarization beam combiner, 5 is the third polarization beam splitter, 6 is the second reflector, 7 is the second polarization beam combiner, 8 is the first laser power meter, 9 is the second laser power meter, 10 is a high-power fiber laser, 11 is a beam expander, 12 is a stable beam splitting device for the laser beam, and 13 is a sampler. Detailed implementation manners
[0062] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments, but the content of the present invention is not limited to the following embodiments only.
[0063] Embodiment 1
[0064] As Figure 1 shown, a stable beam splitting device for a laser beam includes a beam expander, a first polarization beam splitter, a second polarization beam splitter, a first reflector, a first polarization beam combiner, a third polarization beam splitter, a second reflector, and a second polarization beam combiner;
[0065] The beam expander and the first polarization beam splitter are arranged in sequence along the optical path propagation direction;
[0066] Along the propagation direction of the reflected optical path of the first polarization beam splitter and the transmitted optical path of the second polarization beam splitter, the first polarization beam splitter, the second polarization beam splitter, the first reflector, and the first polarization beam combiner are arranged in sequence;
[0067] Along the propagation direction of the reflected optical path of the first polarization beam splitter and the reflected optical path of the second polarization beam splitter, the first polarization beam splitter, the second polarization beam splitter, the second reflector, and the second polarization beam combiner are arranged in sequence;
[0068] Along the propagation direction of the transmitted optical path of the first polarization beam splitter and the reflected optical path of the third polarization beam splitter, the first polarization beam splitter, the third polarization beam splitter, and the first polarization beam combiner are arranged in sequence;
[0069] Along the propagation directions of the transmission optical paths of the first polarization beam splitter and the third polarization beam splitter, the first polarization beam splitter, the third polarization beam splitter, and the second polarization beam combiner are arranged in sequence.
[0070] The beam splitting method using the above-mentioned stable beam splitting device for laser beams is characterized in that it includes the following steps:
[0071] 1) The laser beam It emitted by the high-power fiber laser is expanded by an expander and then split by the first polarization beam splitter (with a splitting ratio of 50%:50%, and in practice, it can also be other ratios such as 40%:60%, 30%:70%, 20%:80%, etc.) into a first beam Ia and a second beam Ib that are perpendicular to each other. Both the first beam Ia and the second beam Ib are pure linearly polarized light. In this example, as Figure 1 shown, the first beam Ia is to the right and the second beam Ib is upward, where It, Ia, and Ib respectively represent the light intensities of the corresponding beams, and It = Ia + Ib; due to the randomness of the polarization direction of the light output by the fiber laser itself, although the laser power output from the high-power fiber laser may be relatively stable, even if the splitting ratio of the first polarization beam splitter is 50%:50%, the intensities of the two beams, the first beam Ia and the second beam Ib, obtained are also different;
[0072] 2) After the first beam Ia passes through the third polarization beam splitter (with a splitting ratio of n%:(100 - n)%, in this example, n takes 0.1, and in practice, n can also be other values such as 0.5, 2, 5, etc.), it is split into a first A beam n%Ia and a first B beam (100 - n)%Ia that are perpendicular to each other; after the second beam Ib passes through the second polarization beam splitter (with the same splitting ratio as the third polarization beam splitter, and in this example, n is also 0.1), it is split into a second A beam n%Ib and a second B beam (100 - n)%Ib;
[0073] 3) The first A beam n%Ia and the second A beam n%Ib reflected by the first reflector are combined by the first polarization beam combiner to obtain n%(Ia + Ib) = n%It, which is 0.1%It in this example; the first B beam (100 - n)%Ia and the second B beam (100 - n)%Ib reflected by the second reflector are combined by the second polarization beam combiner to obtain (100 - n)%(Ia + Ib) = (100 - n)%It, which is 99.9%It in this example, thus completing the stable beam splitting of the laser beam.
[0074] Through the above method, precise beam splitting of the fiber laser with unstable polarization is achieved. The influence of the uncertainty and randomness of the polarization state of the fiber laser on beam splitting is eliminated. No matter how the polarization direction of the fiber laser changes, the laser beam can always be split in real time and accurately according to a specific ratio.
[0075] Example 2
[0076] As Figure 1 shown, a device for applying an industrial fiber laser to the calibration of a laser power meter includes a beam expander, a first polarization beam splitter, a second polarization beam splitter, a first reflector, a first polarization beam combiner, a third polarization beam splitter, a second reflector, a second polarization beam combiner, a first laser power meter, and a second laser power meter; the first laser power meter is a sampling laser power meter, and the second laser power meter is a laser power meter to be measured or a standard laser power meter;
[0077] The beam expander and the first polarization beam splitter are arranged in sequence along the optical path propagation direction;
[0078] Along the propagation direction of the reflected optical path of the first polarization beam splitter and the transmitted optical path of the second polarization beam splitter, the first polarization beam splitter, the second polarization beam splitter, the first reflector, the first polarization beam combiner, and the first laser power meter are arranged in sequence;
[0079] Along the propagation direction of the reflected optical path of the first polarization beam splitter and the reflected optical path of the second polarization beam splitter, the first polarization beam splitter, the second polarization beam splitter, the second reflector, the second polarization beam combiner, and the second laser power meter are arranged in sequence;
[0080] Along the propagation direction of the transmitted optical path of the first polarization beam splitter and the reflected optical path of the third polarization beam splitter, the first polarization beam splitter, the third polarization beam splitter, the first polarization beam combiner, and the first laser power meter are arranged in sequence;
[0081] Along the propagation direction of the transmitted optical path of the first polarization beam splitter and the transmitted optical path of the third polarization beam splitter, the first polarization beam splitter, the third polarization beam splitter, the second polarization beam combiner, and the second laser power meter are arranged in sequence.
[0082] For the convenience of simultaneous reading, as Figure 2 shown, the above-mentioned first laser power meter and second laser power meter are both connected to a sampler and transmit the detected data to the sampler simultaneously.
[0083] A method for calibrating a laser power meter by using the above device for applying an industrial fiber laser to the calibration of a laser power meter includes the following steps:
[0084] 1) The laser beam It emitted by a high-power fiber laser (2000W) is expanded by a beam expander and then divided by a first polarization beam splitter (the splitting ratio is 50%:50%, and in practice, it can also be other ratios such as 40%:60%, 30%:70%, 20%:80%, etc.) into a first beam Ia and a second beam Ib that are perpendicular to each other. The first beam Ia and the second beam Ib are both pure linearly polarized light. In this example, as Figure 1As shown, the first light beam Ia is directed to the right, and the second light beam Ib is directed upward. Here, It, Ia, and Ib represent the light intensities of the corresponding light beams respectively, and It = Ia + Ib. Due to the randomness of the polarization direction of the light output by the fiber laser itself, although the laser power output from the high-power fiber laser may be relatively stable, even if the splitting ratio of the first polarization beam splitter is 50%:50%, the intensities of the two light beams, the first light beam Ia and the second light beam Ib, obtained are not the same.
[0085] 2) After the first light beam Ia passes through the third polarization beam splitter (with a splitting ratio of n%:(100 - n)%, in this example, n is taken as 0.1, and through practice, n can also be other values such as 0.5, 2, 5, etc.), it is divided into a first A light beam n%Ia and a first B light beam (100 - n)%Ia that are perpendicular to each other; after the second light beam Ib passes through the second polarization beam splitter (with the same splitting ratio as the third polarization beam splitter, and n is also 0.1 in this example), it is divided into a second A light beam n%Ib and a second B light beam (100 - n)%Ib.
[0086] 3) The first A light beam n%Ia and the second A light beam n%Ib reflected by the first mirror are combined by the first polarization beam combiner to obtain n%(Ia + Ib) = n%It, which is detected by the first laser power meter and is 0.1%It in this example; the first B light beam (100 - n)%Ia and the second B light beam (100 - n)%Ib reflected by the second mirror are combined by the second polarization beam combiner to obtain (100 - n)%(Ia + Ib) = (100 - n)%It, which is 99.9%It in this example and is detected by the second laser power meter.
[0087] Regardless of how unstable the relative intensities of the two split light beams Ia and Ib are due to the uncertainty of laser polarization, the optical power detected by the first laser power meter is n% of the total laser output power, which is determined; and the optical power detected by the second laser power meter is (100 - n)% of the total laser output power, which is also a determined value.
[0088] Generally, any physical quantity is a function of time and continuously fluctuates with time. The output power of the fiber laser is no exception. If the fiber laser is directly used to first measure the reading of the standard laser power meter and then measure the reading of the laser power meter to be tested, due to the different times of the two measurements, an error is introduced due to the fluctuation of the laser output power. Therefore, the calibration operation of the power meter cannot be simply carried out by comparing the two measurement values; the above-mentioned fiber laser with random polarization is divided into two light beams with a determined ratio, one of which is the sampling light beam n%It and the other is the measurement light beam (100 - n)%It. The following uses the synchronous double-sampling method to simultaneously read the values of the sampling light beam and the measurement light beam to eliminate the time fluctuation error of the laser output. The specific calibration process is as follows:
[0089] First, install a standard laser power meter. Both the sampling laser power meter and the standard laser power meter are connected to the sampler and transmit the detected data to the sampler simultaneously. That is, the readings of the sampling laser power meter and the standard laser power meter are obtained simultaneously, and the functional relationship f1 between the readings of the sampling laser power meter and the standard laser power meter is obtained by fitting, as Figure 3 shown;
[0090] Second, replace the standard laser power meter with the laser power meter to be measured. Both the sampling laser power meter and the laser power meter to be measured are connected to the sampler and transmit the detected data to the sampler simultaneously. That is, the readings of the sampling laser power meter and the laser power meter to be measured are obtained simultaneously, and the functional relationship f2 between the readings of the sampling laser power meter and the laser power meter to be measured is obtained by fitting, as Figure 4 shown;
[0091] Finally, through the conversion of f1 and f2, the functional relationship f3 between the reading of the laser power meter to be measured and the reading of the standard laser power meter is obtained, as Figure 5 shown, and the calibration of the standard laser power meter is realized by using f3.
[0092] The accuracy of the above beam splitting reaches 100%. Through the accurate beam splitting of the industrial high-power fiber laser, the precise calibration of the high-power laser power meter is realized by using the high-power fiber laser with a random polarization direction. In this example, the standard laser power meter used is Pronto-3k, and the reference laser power meter is UP50M-50W-W9-D0. It has been verified that the calibration using the above device and method does not cause any reduction in the accuracy rate of the standard laser power meter.
Claims
1. A method for stably splitting a laser beam, characterized in that: It includes the following steps: 1) Divide the laser beam It into a first beam Ia and a second beam Ib. Both the first beam Ia and the second beam Ib are pure linearly polarized light. Here, It, Ia, and Ib represent the light intensities of the corresponding beams respectively, and It = Ia + Ib; 2) Divide the first beam Ia into a first A beam n%Ia and a first B beam (100 - n)%Ia; divide the second beam Ib into a second A beam n%Ib and a second B beam (100 - n)%Ib; 3) Combine the first A beam n%Ia and the second A beam n%Ib to obtain n% It; combine the first B beam (100 - n)%Ia and the second B beam (100 - n)%Ib to obtain (100 - n)% It, achieving stable splitting of the laser beam.
2. The method for stably splitting a laser beam according to claim 1, wherein: In step 1), first expand the laser beam It and then divide it into the first beam Ia and the second beam Ib.
3. The method for stably splitting a laser beam according to claim 1 or 2, characterized in that: In step 1), divide the laser beam It into the first beam Ia and the second beam Ib which are perpendicular to each other; in step 2), divide the first beam Ia into the first A beam n%Ia and the first B beam (100 - n)%Ia which are perpendicular to each other; divide the second beam Ib into the second A beam n%Ib and the second B beam (100 - n)%Ib which are perpendicular to each other.
4. A method for calibrating a laser power meter using the method for stably splitting a laser beam according to any one of claims 1-3, characterized in that: It includes the following steps: First, simultaneously detect n% It using a sampling laser power meter and detect (100 - n)% It using a standard laser power meter, and fit the readings of the sampling laser power meter and the standard laser power meter obtained to get the functional relationship f1 between the readings of the sampling laser power meter and the standard laser power meter; Second, simultaneously detect n% It using a sampling laser power meter and detect (100 - n)% It using a laser power meter to be measured, and fit the readings of the sampling laser power meter and the laser power meter to be measured obtained to get the functional relationship f2 between the readings of the sampling laser power meter and the laser power meter to be measured; Finally, through the conversion of f1 and f2, obtain the functional relationship f3 between the reading of the laser power meter to be measured and the reading of the standard laser power meter, and use the functional relationship f3 to calibrate the standard laser power meter.
5. A stable beam splitting device for a laser beam, characterized in that: It includes a first polarization beam splitter, a second polarization beam splitter, a first reflector, a first polarization beam combiner, a third polarization beam splitter, a second reflector, and a second polarization beam combiner; Along the propagation direction of the reflection optical path of the first polarization beam splitter and the transmission optical path of the second polarization beam splitter, the first polarization beam splitter, the second polarization beam splitter, the first reflector, and the first polarization beam combiner are arranged in sequence; Along the propagation direction of the reflection optical paths of the first polarization beam splitter and the second polarization beam splitter, the first polarization beam splitter, the second polarization beam splitter, the second reflector, and the second polarization beam combiner are arranged in sequence; Along the propagation direction of the transmission optical path of the first polarization beam splitter and the reflection optical path of the third polarization beam splitter, the first polarization beam splitter, the third polarization beam splitter, and the first polarization beam combiner are arranged in sequence; Along the propagation directions of the transmission optical paths of the first polarization beam splitter and the third polarization beam splitter, the first polarization beam splitter, the third polarization beam splitter and the second polarization beam combiner are arranged in sequence. The laser beam It emitted by the high-power fiber laser is split by the first polarization beam splitter into a first beam Ia and a second beam Ib that are perpendicular to each other. Here, It, Ia, and Ib respectively represent the light intensities of the corresponding beams, and It = Ia + Ib. After the first beam Ia passes through the third polarization beam splitter, it is split into a first A beam n%Ia and a first B beam (100 - n)%Ia that are perpendicular to each other; after the second beam Ib passes through the second polarization beam splitter, it is split into a second A beam n%Ib and a second B beam (100 - n)%Ib that are perpendicular to each other; the first A beam n%Ia and the second A beam n%Ib reflected by the first reflector are combined by the first polarization beam combiner to obtain n%(Ia + Ib) = n%It; the first B beam (100 - n)%Ia and the second B beam (100 - n)%Ib reflected by the second reflector are combined by the second polarization beam combiner to obtain (100 - n)%(Ia + Ib) = (100 - n)%It, completing the stable splitting of the laser beam.
6. The stable beam splitting device for laser beams according to claim 5, characterized in that: It further includes a beam expander, which is arranged upstream of the first polarization beam splitter along the optical path propagation direction; the splitting ratios of the second polarization beam splitter and the third polarization beam splitter are the same.
7. A splitting method of a laser beam using the laser beam splitting device according to claim 5 or 6, characterized in that: It includes the following steps: 1) The laser beam It emitted by the high-power fiber laser is split by the first polarization beam splitter into a first beam Ia and a second beam Ib that are perpendicular to each other. Here, It, Ia, and Ib respectively represent the light intensities of the corresponding beams, and It = Ia + Ib. 2) After the first beam Ia passes through the third polarization beam splitter, it is split into a first A beam n%Ia and a first B beam (100 - n)%Ia that are perpendicular to each other; after the second beam Ib passes through the second polarization beam splitter, it is split into a second A beam n%Ib and a second B beam (100 - n)%Ib that are perpendicular to each other. 3) The first A beam n%Ia and the second A beam n%Ib reflected by the first reflector are combined by the first polarization beam combiner to obtain n%(Ia + Ib) = n%It; the first B beam (100 - n)%Ia and the second B beam (100 - n)%Ib reflected by the second reflector are combined by the second polarization beam combiner to obtain (100 - n)%(Ia + Ib) = (100 - n)%It, completing the stable splitting of the laser beam.
8. The spectroscopic method according to claim 7, wherein: In step 1), the laser beam It emitted by the high-power fiber laser is expanded by the beam expander and then split by the first polarization beam splitter into a first beam Ia and a second beam Ib that are perpendicular to each other.
9. A device for calibrating a laser power meter by applying an industrial fiber laser, characterized in that: It includes a first polarization beam splitter, a second polarization beam splitter, a first reflector, a first polarization beam combiner, a third polarization beam splitter, a second reflector, a second polarization beam combiner, a first laser power meter and a second laser power meter; the first laser power meter is a sampling laser power meter, and the second laser power meter is a laser power meter to be measured or a standard laser power meter. Along the propagation directions of the reflection optical path of the first polarization beam splitter and the transmission optical path of the second polarization beam splitter, the first polarization beam splitter, the second polarization beam splitter, the first reflector, the first polarization beam combiner, and the first laser power meter are arranged in sequence; Along the propagation directions of the reflection optical path of the first polarization beam splitter and the reflection optical path of the second polarization beam splitter, the first polarization beam splitter, the second polarization beam splitter, the second reflector, the second polarization beam combiner, and the second laser power meter are arranged in sequence; Along the propagation directions of the transmission optical path of the first polarization beam splitter and the reflection optical path of the third polarization beam splitter, the first polarization beam splitter, the third polarization beam splitter, the first polarization beam combiner, and the first laser power meter are arranged in sequence; Along the propagation directions of the transmission optical path of the first polarization beam splitter and the transmission optical path of the third polarization beam splitter, the first polarization beam splitter, the third polarization beam splitter, the second polarization beam combiner, and the second laser power meter are arranged in sequence; The laser beam It emitted by the high-power fiber laser is divided by the first polarization beam splitter into a first beam Ia and a second beam Ib that are perpendicular to each other. Among them, It, Ia, and Ib represent the light intensities of the corresponding beams respectively, and It = Ia + Ib; After the first beam Ia passes through the third polarization beam splitter, it is divided into a first A beam n%Ia and a first B beam (100 - n)%Ia that are perpendicular to each other; after the second beam Ib passes through the second polarization beam splitter, it is divided into a second A beam n%Ib and a second B beam (100 - n)%Ib that are perpendicular to each other; the first A beam n%Ia and the second A beam n%Ib reflected by the first reflector are combined by the first polarization beam combiner to obtain n%(Ia + Ib) = n%It; the first B beam (100 - n)%Ia and the second B beam (100 - n)%Ib reflected by the second reflector are combined by the second polarization beam combiner to obtain (100 - n)%(Ia + Ib) = (100 - n)%It, completing the stable splitting of the laser beam.
10. The device for calibrating a laser power meter by applying an industrial fiber laser as claimed in claim 9, wherein: It also includes a beam expander, which is arranged upstream of the first polarization beam splitter along the optical path propagation direction; it also includes a sampler. Both the first laser power meter and the second laser power meter are connected to the sampler and transmit data to the sampler simultaneously; the splitting ratios of the second polarization beam splitter and the third polarization beam splitter are the same.
11. A method for calibrating a laser power meter by applying an industrial fiber laser, which is calibrated by using the device for calibrating a laser power meter by applying an industrial fiber laser according to claim 9 or 10, characterized in that: It includes the following steps: 1) The laser beam It of the high-power fiber laser is divided by the first polarization beam splitter into a first beam Ia and a second beam Ib that are perpendicular to each other. Among them, It, Ia, and Ib represent the light intensities of the corresponding beams respectively, and It = Ia + Ib; 2) After the first beam Ia passes through the third polarization beam splitter, it is divided into a first A beam n%Ia and a first B beam (100 - n)%Ia that are perpendicular to each other; after the second beam Ib passes through the second polarization beam splitter, it is divided into a second A beam n%Ib and a second B beam (100 - n)%Ib that are perpendicular to each other; 3) The first A beam n%Ia and the second A beam n%Ib reflected by the first reflector are combined by the first polarization beam combiner to obtain n%(Ia + Ib) = n%It, which is detected by the first laser power meter; the first B beam (100 - n)%Ia and the second B beam (100 - n)%Ib reflected by the second reflector are combined by the second polarization beam combiner to obtain (100 - n)%(Ia + Ib) = (100 - n)%It, which is detected by the second laser power meter. The first laser power meter is a sampling laser power meter, and the second laser power meter is a laser power meter to be measured or a standard laser power meter. The specific process is as follows: First, install the standard laser power meter, and at the same time obtain the readings of the sampling laser power meter and the standard laser power meter, and fit to obtain the functional relationship f1 between the readings of the sampling laser power meter and the standard laser power meter; Secondly, replace the standard laser power meter with the laser power meter to be measured, and at the same time obtain the readings of the sampling laser power meter and the laser power meter to be measured, and fit to obtain the functional relationship f2 between the readings of the sampling laser power meter and the laser power meter to be measured; Finally, through the conversion of f1 and f2, obtain the functional relationship f3 between the readings of the laser power meter to be measured and the standard laser power meter, and use f3 to realize the calibration of the standard laser power meter.
Citation Information
Patent Citations
Stable laser beam splitting device and laser power meter calibration device
CN217687505U