A coaxial transmission type damage threshold automatic measuring system

Abstract

The present application relates to optical measuring instrument equipment technical field, especially to a coaxial transmission type damage threshold automatic measuring system, solve the measurement in the prior art to avoid direct measurement to strong light and reduce the image processing error caused by sample impurities and uneven, namely, sample impurities affect image processing and the technical problem of missed detection caused by unobvious damage morphology, specifically configuration adopts computer and time sequence pulse generator automatic control CMOS camera, rotating wheel, energy meter, laser, two bit translation table and collects data, and carries out damage threshold calculation. The advantage of the present application is that the intensity distribution analysis of transmission detection spot is used, which is not only sensitive to transmittance, but also can detect irreversible phase change caused by laser damage; the coaxial transmission light path and weak-strong-weak mode measurement scheme are adopted, which is matched with corresponding computer control and data acquisition, so that direct measurement to strong light can be avoided, and image processing error caused by sample impurities and uneven can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical measuring instruments, in particular to a coaxial transmission type damage threshold automatic measuring system. BACKGROUND

[0002] The laser damage threshold is an important parameter index of laser-related optical materials and elements of a laser, that is, the maximum laser energy or power density that an optical element can withstand, and when the threshold is exceeded, the material will be damaged;

[0003] Unlike general optical elements or material samples, nonlinear crystals, optical limiting materials, and their surface antireflection films, photodetector substrates, and transparent electrodes, etc. transparent or semi-transparent materials have low light absorption rates in the response band (in-band), and it is difficult to cause electronic transition and subsequent energy conversion, so they usually have high in-band damage thresholds;

[0004] Under in-band damage, damage is usually caused by local heat sources generated by internal medium concentration, impurities, etc. defects, and around the impurity particles, there may be "crater" shaped damage pits, bulk damage, and other typical damage morphologies commonly seen in transmission damage.

[0005] In particular, near the damage threshold, the damage characteristics of the transparent medium may not be obvious under a microscope, so it is easy to be ignored when counting the ablation points, resulting in inaccurate measurement results. Therefore, the traditional method of using an optical microscope for observation and counting ablation points based on image processing is difficult to extract an accurate damage threshold.

[0006] In the prior art, Chinese invention application, publication number CN115096553A, entitled "Laser damage threshold measurement method and device" also uses a transmission type optical path; but this scheme uses damage-detection double optical path measurement, the system is relatively complex, the construction cost is relatively high, and other influencing factors are easily introduced due to the off-axis of the detection light path, at the same time, this scheme only measures the transmittance of the sample to be measured, and does not consider the change of optical properties due to the change of internal structure of the material.

[0007] In order to accurately measure the damage threshold of the transparent sample to the corresponding waveband laser, it is necessary to use a coaxial optical path to measure the transmission spot distribution of the damaged position, and at the same time, an image processing method is used to automatically analyze the mutation degree of the transmission spot distribution, so as to realize the automatic and accurate measurement of the damage threshold with high sensitivity. SUMMARY

[0008] The present application solves the technical problems of avoiding direct measurement of strong light and reducing image processing errors caused by sample impurities and non-uniformity during measurement in the prior art, that is, the technical problem of sample impurity affecting image processing and the problem of missed detection caused by unobvious damage morphology, and provides a coaxial transmission type damage threshold automatic measuring system.

[0009] To solve the above technical problems, the technical scheme of the present application is as follows:

[0010] A coaxial transmission type damage threshold automatic measurement system comprises:

[0011] A control terminal, which is a computer 10, is used to control a laser 20 to output two kinds of pulse light through an electric filter rotating wheel 30.

[0012] The two kinds of pulse light are weak light that cannot damage the sample and strong light near the damage threshold, respectively.

[0013] The weak light that cannot damage the sample is generated by a neutral filter on the optical axis.

[0014] The strong light near the damage threshold is generated by an empty light transmission hole on the optical axis.

[0015] The pulse light is reflected by a sampling mirror 40 to output a small part of light as sampling energy into an energy meter 50.

[0016] The energy meter 50 can represent the pulse energy of the incident laser by calibrating the sampling energy and the beam energy of the main light path, so as to calculate the energy density.

[0017] The main light path beam is focused on the sample to be measured by a wide-band reflector 60 and a wide-band focusing mirror 70 adjusted by a slider adjustment structure, so as to realize the damage of the sample.

[0018] The slider adjustment structure can adjust the positions of the wide-band reflector 60 and the wide-band focusing mirror 70 through the adjustment action.

[0019] The sample is placed on a hollow two-dimensional translation stage, so that the light beam can pass through the hollow position and irradiate onto the receiving screen (130) below.

[0020] The receiving screen 130 is a white screen or a conversion screen.

[0021] When the white screen is used, the spot projection is used for visible laser.

[0022] When the conversion screen is used, the spot projection is used for infrared laser.

[0023] A hollow plate 121 is arranged on the two-dimensional translation stage.

[0024] In an off-axis direction, a CMOS camera 110 is set up. The laser 20 and the CMOS camera 110 are synchronously controlled by the timing pulse generator 120 to capture the transmitted light spot. The laser pulse energy data collected by the energy meter 50 is then transmitted to the computer 10 in real time to complete the test steps.

[0025] Specifically, the main optical path is a coaxial transmission optical path, which uses three pulses (weak, strong, and weak) to collect the transmitted light spot, sample damage, and damaged transmitted light spot, respectively.

[0026] Specifically, the slider adjustment structure includes:

[0027] A stainless steel connecting rod 13 is provided with a first slider 11 and a second slider 12 that can slide on the stainless steel connecting rod 13 and be locked on the stainless steel connecting rod 13.

[0028] Specifically, the test steps include:

[0029] First, the computer 10 controls the electric filter wheel 30 to insert the filter into the optical path and controls the laser to emit a pulse, while simultaneously recording its energy and transmitted light spot. At this time, it is a weak light transmission.

[0030] Then control the electric filter wheel 30 to rotate to the empty hole position, control the laser 20 to emit one or more pulses to cause damage, and record its pulse energy. At this time, strong light is transmitted.

[0031] Next, repeat the weak light transmission steps described above and measure the transmitted light spot and pulse energy of the weak light after sample damage once more. This completes one cycle of the weak-strong-weak mode, which is equivalent to completing the measurement of one point.

[0032] Control the two-dimensional translation stage to move the relative position of the sample and repeat the test points;

[0033] Finally, the differences in light spots between the two weak light transmission tests were compared based on the overall transmittance criterion and the light spot morphology criterion.

[0034] Specifically, the testing steps also include a preparatory stage, the contents of which are as follows:

[0035] Confirm the connection of all components in the system and test the on / off control.

[0036] The transmitted pulse energy E of the sampling mirror 40 was measured. T With sampling pulse energy E S The ratio of r ST The transmitted pulse energy, E, is calibrated using the sampled pulse energy. T =r ST E S;

[0037] Adjusting the first slider 11 and the second slider 12 to make the sample surface close to the focal point;

[0038] Placing the knife on the light window of the hollow two-dimensional translation stage, the knife-edge method can be used to measure the size of the focused spot;

[0039] Wherein, the quotient of the pulse energy and the spot area is the pulse energy density.

[0040] Specifically, the test step further includes a collection stage, and the content of the collection stage is:

[0041] Step S1, using the computer 10 to control the electric filter wheel 20 to emit a weak light pulse, and synchronously collecting the sample pulse energy data Ew0 through the energy meter;

[0042] Step S2, collecting the spot photo Im0 projected on the conversion screen or the white screen through the CMOS camera 110;

[0043] Step S3, controlling the electric filter wheel 20 to emit 1 or S strong light pulses, recording E S And calculating the pulse energy data E T ;

[0044] Wherein, the pulse energy data E T In the case of single pulse, it is a number, and in the case of multiple pulses, it is an array of 1xS, that is, corresponding to 1 to 1 and S to 1 test;

[0045] Step S4, finally controlling the electric filter wheel 20 to emit a weak light pulse, and collecting the sample pulse energy data Ew1 through the energy meter 50, and collecting the spot photo Im1 projected on the conversion screen through the sample again.

[0046] Specifically, it further includes:

[0047] When the measurement of one point corresponding to the steps S1 to S4 is completed, the computer 10 is used to control the hollow two-dimensional translation stage 100 to move the sample to the next point to be measured, and the steps S1 to S4 are completed again.

[0048] The number of measurements of the point is any number in 50-100 times.

[0049] Specifically, it further includes a data processing stage, and the content of the data processing stage includes:

[0050] By performing edge detection, open-close operation and other image processing on the light spot photos Im0 and Im1, the Euler number, the standard second-order central moment long and short axes of the light spot, and the ratio of the integral gray value of the light spot photos Im0 / Im1 to the pulse energy Ew0 / Ew1 are calculated.

[0051] The present application has the following advantages:

[0052] The present application has the following advantages:

[0053] In the second aspect, the present application uses a coaxial transmission light path and a weak-strong-weak mode measurement scheme, cooperates with corresponding computer control and data acquisition, can avoid direct measurement of strong light and reduce image processing errors caused by sample impurities and non-uniformity, and thus solves the problems of automation and sensitivity of the existing measurement scheme. BRIEF DESCRIPTION OF DRAWINGS

[0054] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0055] Figure 1 The present application has the following advantages:

[0056] Figure 2 The present application has the following advantages: Figure 2 Comparison of advantages and disadvantages of coaxial and off-axis damage detection

[0057] Figure 3 The present application has the following advantages: Figure 3 Micrographs of not obvious (red) and more obvious damage pits (green)

[0058] Figure 4a The present application has the following advantages:

[0059] Figure 4b The present application has the following advantages:

[0060] Figure 4c The present application has the following advantages: DETAILED DESCRIPTION

[0061] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of the present application. It should be noted that, in the present application, in order to facilitate description, the "left side" in the current view is the "first end", the "right side" is the "second end", the "upper side" is the "first end", and the "lower side" is the "second end". The purpose of such description is to clearly express the technical solutions, and should not be understood as an improper limitation on the technical solutions of the present application.

[0062] The present application aims to solve the technical problems in the prior art, such as avoiding direct measurement of strong light and reducing image processing errors caused by sample impurities and non-uniformity during measurement, i.e., sample impurities affecting image processing and missing detection caused by non-obvious damage morphology, and provides a coaxial transmission type damage threshold automatic measurement system.

[0063] Specifically, the prior art damage threshold automatic measurement scheme is divided into two types.

[0064] One is to directly observe the damage morphology by microscopy after damage and perform image processing.

[0065] The other is to use a transmission or reflection light path to detect the transmittance and reflectance changes caused by damage.

[0066] However, both of the above-mentioned schemes are difficult to detect the damage caused by the subtle structural changes due to internal stress of the material, especially in the case of near damage threshold, which directly leads to overestimation of the damage threshold of such materials.

[0067] The advantage of the present application is that the intensity distribution analysis of the transmission detection light spot is not only sensitive to transmittance, but also can detect the irreversible phase changes caused by laser damage.

[0068] In the second aspect, the present application uses a coaxial transmission light path and a weak-strong-weak measurement scheme, combined with corresponding computer control and data acquisition, to avoid direct measurement of strong light and reduce image processing errors caused by sample impurities and non-uniformity, thereby solving the problems of automation and sensitivity of the existing measurement scheme.

[0069] Please refer to the accompanying drawings Figure 1 for a description. The collimated input laser beam wavelength is a visible to near-infrared nanosecond (0.5-1.6 μm) pulse laser 20. In the specific embodiments involved in the present application, the maximum pulse energy is 400 mJ, the pulse width is 4 ns, the wavelength is 1064 nm / 532 nm, the repetition frequency is 10 Hz, and the single pulse can be triggered.

[0070] The laser 20 is controlled by the computer 10 to generate a pulse of about 0.1 mJ, and the motorized filter wheel 30 is controlled to place the light passage hole with the neutral filter OD2 on the optical axis, so that the energy of the pulse after passing through the filter is about 1 μJ, i.e. the weak light pulse.

[0071] When the motorized filter wheel 30 is controlled to place the empty light passage hole on the optical axis, a pulse of about 0.1 mJ is emitted, i.e. the strong light pulse;

[0072] The Figure 1 A white screen or a switching up-conversion screen can be used in the embodiment for the damage threshold measurement of the visible and infrared waveband lasers respectively.

[0073] The up-conversion screen can be used for the spot projection of the infrared laser.

[0074] In the specific technical solution, the coaxial transmission type damage threshold automatic measurement system comprises:

[0075] The control terminal is the computer 10, which is used to control the laser 20 to output two kinds of pulse lights through the motorized filter wheel 30;

[0076] The two kinds of pulse lights are respectively weak light which cannot damage the sample and strong light near the damage threshold;

[0077] The weak light which cannot damage the sample is generated by placing the neutral filter on the optical axis;

[0078] The strong light near the damage threshold is generated by placing the empty light passage hole on the optical axis;

[0079] The pulse light passes through a sampling mirror 40 to reflect a small part of light as sampling energy into an energy meter 50;

[0080] The energy meter 50 can characterize the pulse energy of the incident laser by calibrating the sampling energy and the beam energy of the main light path, so as to calculate the energy density;

[0081] The main light path beam passes through the wide-spectrum reflecting mirror 60 and the wide-spectrum focusing mirror 70 which are adjusted by the slider adjustment structure

[0082] The main light path beam is focused on the sample to be measured, so as to realize the damage of the sample;

[0083] The slider adjustment structure can adjust the positions of the wide-spectrum reflecting mirror 60 and the wide-spectrum focusing mirror 70 by adjustment actions, so as to switch the output wavelength of the laser without replacing the optical elements in the system to avoid the introduction of errors due to the re-establishment of the system.

[0084] The sample is placed on the hollow two-dimensional translation stage, so that the light beam can pass through the hollow position and irradiate onto the receiving screen 130 below.

[0085] The receiving screen 130 is a white screen or a conversion screen.

[0086] When the white screen is used, the spot projection is used for visible laser.

[0087] When the conversion screen is used, the spot projection is used for infrared laser.

[0088] A hollow plate 121 is arranged on the two-dimensional translation table.

[0089] In an off-axis direction, a CMOS camera 110 is arranged, and the laser 20 and the CMOS camera 110 are synchronously controlled by a time sequence pulse generator 120 to capture the transmitted spot, and the laser pulse energy data collected by the energy meter 50 are synchronously transmitted to the computer 10 in real time to complete the test step.

[0090] In a more specific technical solution, the main light path is a coaxial transmission type light path, and the collection of the transmitted spot, the sample damage, and the collection of the damaged transmitted spot are realized by three times of weak, strong, and weak pulses.

[0091] In a more specific technical solution, the sliding block adjusting structure comprises:

[0092] A stainless steel connecting rod 13 is arranged with a first sliding block 11 and a second sliding block 12 which can slide on the stainless steel connecting rod 13 and can be locked on the stainless steel connecting rod 13.

[0093] In a more specific technical solution, the test step comprises:

[0094] First, the computer 10 is used to control the electric filter rotating wheel 30 to insert the filter into the light path, and the laser is controlled to emit one pulse, and the energy and the transmitted spot are recorded synchronously, at this time, it is weak light transmission.

[0095] Then, the electric filter rotating wheel 30 is controlled to rotate to the empty hole position, the laser 20 is controlled to emit one or more pulses to cause damage, and the pulse energy is recorded, at this time, it is strong light transmission.

[0096] Then, the above weak light transmission step is repeated to measure the transmitted spot and the pulse energy of the weak light after the sample is damaged once again, and one cycle of the above weak-strong-weak mode is completed to complete the measurement of one point.

[0097] The two-dimensional translation table is controlled to move the relative position of the sample, and the test point is repeated.

[0098] Finally, the difference between the two weak light transmission spots is compared based on the overall transmittance criterion and the spot morphology criterion.

[0099] More specifically, the test procedure further comprises a preliminary stage, the content of which is:

[0100] Confirming the connection of the components of the system and debugging the control of the on-off;

[0101] By actually measuring the transmitted pulse energy E T of the sampling mirror 40, and the sampling pulse energy E S , the ratio r ST is obtained, and the transmitted pulse energy is calibrated using the sampling pulse energy, i.e. E T = r ST E S ;

[0102] Adjust the first slider 11 and the second slider 12 so that the sample surface is close to the vicinity of the focal point;

[0103] Place the knife edge on the light window of the hollow two-dimensional translation stage, and use the knife edge method to measure the size of the focused light spot;

[0104] The quotient of the pulse energy and the spot area is the pulse energy density;

[0105] In the specific embodiment, the corresponding spot size is about 48.5 μm, and when a strong light pulse is incident, the pulse energy density F in the vicinity of the focal point is about 5.4 J / cm 2 .

[0106] Further comprising a collection stage, the content of which is:

[0107] Step S1: use the computer 10 to control the motorized filter wheel 20 to emit a weak light pulse, and synchronously collect the sampling pulse energy data Ew0 through the energy meter;

[0108] Step S2: collect the light spot photo Im0 projected on the conversion screen 90 or the white screen through the CMOS camera 110;

[0109] Step S3: control the motorized filter wheel 20 to emit 1 or S strong light pulses, record E S , and calculate the pulse energy data E T ;

[0110] Wherein, the pulse energy data E T is a number in the case of single pulse, and is an array of 1×S in the case of multiple pulses, i.e. corresponding to 1-to-1 and S-to-1 tests;

[0111] Step S4: finally control the motorized filter wheel 20 to emit a weak light pulse, and collect the sampling pulse energy data Ew1 through the energy meter 50, and again collect the light spot photo Im1 projected on the conversion screen through the CMOS camera 110.

[0112] The above steps are sequentially performed: measuring the light spot and pulse energy of weak light transmitted through the intact sample; damaging the sample by strong light pulse; measuring the light spot and pulse energy of weak light transmitted through the damaged position, i.e. the weak-strong-weak mode of the present patent.

[0113] Further, after the measurement of one point by steps S1 to S4 is completed, the hollow two-dimensional translation stage 100 is moved to the next point to be measured by using the computer 10, and steps S1 to S4 are again completed.

[0114] The number of measurements of the point is any number between 50 and 100 times;

[0115] Corresponding to the above weak-strong-weak mode program, 50-100 points are measured to complete automatic acquisition.

[0116] Further, the data processing stage includes: calculating the Euler number (i.e. topological parameter), the standard second-order central moment major and minor axes (i.e. shape parameter), and the ratio of the integral gray value of the light spot photo Im0 / Im1 to the pulse energy Ew0 / Ew1 (i.e. transmittance parameter) by performing edge detection, opening and closing operation and other image processing on the light spot photos Im0 and Im1; and determining that damage has occurred when the change rate of these parameters is higher than a certain threshold.

[0117] Finally, the data are processed by referring to the method 1 on 1 and S on 1 test described in GB / T 16601.2-2017, Laser and Laser-Related Equipment, Test Method for Laser Damage Threshold, Part 2: Threshold Determination (see Annex A-D of Laser and Laser-Related Equipment, Test Method for Laser Damage Threshold, Part 2: Threshold Determination), so as to obtain the damage threshold of the sample.

[0118] It should be noted that the white screen is used for imaging the light spot in the visible band, and the conversion screen is used for imaging the light spot in the infrared band, and they have nothing to do with the strong and weak light in the case of not being damaged by the laser. It should be noted that one of the purposes of setting the detection light spot for weak light is to prevent the strong scattered light from interfering or damaging the imaging photoelectric detector (CCD / CMOS), so the CCD / CMOS can be optionally turned off under strong light. The main purpose is to detect the current optical state of the sample without causing changes in the sample.

[0119] Please refer to Fig. 1 Figure 1 As shown in Fig. 1, the coaxial transmission type damage threshold automatic measurement system is configured to use a computer and a time sequence pulse generator to automatically control a CMOS camera, a rotating wheel, an energy meter, a laser, a two-dimensional translation stage and collect data, and calculate the damage threshold.

[0120] Please refer to Fig. 1 Figure 2The advantages and disadvantages of coaxial and off-axis damage detection are compared in the following table Figure 2 In the coaxial transmission system, the probe light path and the damage light path are coaxial, and the spatial overlap of the two light paths is higher, and the light path is easy to realize, so the cost is lower.

[0121] Please refer to the following table Figure 3 The micrographs of the unobvious (red) and the more obvious damage pits (green) are shown in the following table

[0122] The following table shows the damage pit photos of the quartz piece under 532nm laser Figure 3 The center of the unobvious damage pit has no obvious color change, and the annular pit caused by structural change is also not very obvious, so it is easy to be ignored during image processing, especially in the case of more impurities in the sample Figure 4a The sample platform top view of the coaxial transmission damage threshold automatic measurement system

[0123] The following table shows the damage pit photos of the quartz piece under 532nm laser Figure 4b The light spot before damage of the quartz piece is shown in the following table Figure 4c The light spot after damage

[0124] The following table shows the damage pit photos of the quartz piece under 532nm laser Figure 4a The following table shows the damage pit photos of the quartz piece under 532nm laser Figure 4b , The following table shows the damage pit photos of the quartz piece under 532nm laser Figure 4c The following table shows the damage pit photos of the quartz piece under 532nm laser

[0125] Obviously, the above examples are only examples for the purpose of clarity, and are not limited to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A coaxial transmission type damage threshold automatic measuring system, characterized by, The application relates to a laser damage test device and a test method thereof. The device comprises: a control terminal, which is a computer (10) for controlling a laser (20) to output two kinds of pulse lights through an electric filter wheel (30); the two kinds of pulse lights are weak light incapable of damaging a sample and strong light near a damage threshold; the weak light incapable of damaging the sample is generated on an optical axis through a neutral filter; the strong light near the damage threshold is generated on the optical axis through an empty light transmission hole; the pulse light is reflected by a sampling mirror (40) to output a small amount of light as sampling energy into an energy meter (50); the energy meter (50) can represent the pulse energy of incident laser light by calibrating the sampling energy and the energy of a main light path light beam so as to calculate the energy density; the main light path light beam passes through a wide-spectrum reflecting mirror (60) and a wide-spectrum focusing mirror (70) which are adjusted by a slider adjustment structure; the light beam is focused on a sample to be tested so as to damage the sample; the slider adjustment structure can adjust the positions of the wide-spectrum reflecting mirror (60) and the wide-spectrum focusing mirror (70) through the adjustment action; the sample is arranged on a hollow two-dimensional translation table so that the light beam can pass through the hollow position and irradiate onto a receiving screen (130) below; the receiving screen (130) is a white screen or a conversion screen; when the white screen is used, the white screen is used for spot projection of visible laser light; when the conversion screen is used, the conversion screen is used for spot projection of infrared laser light; a hollow plate (121) is arranged on the two-dimensional translation table; a CMOS camera (110) is arranged in an off-axis direction, the laser (20) and the CMOS camera (110) are synchronously controlled through a time sequence pulse generator (120) and controlled by the control terminal to capture the transmission spot, and the laser pulse energy data collected by the energy meter (50) are synchronously transmitted to the computer (10) in real time so as to complete a test step; the main light path is a coaxial transmission type light path, and the collection of the transmission spot, the damage of the sample and the collection of the damaged transmission spot are realized through three times of weak, strong and weak pulses respectively.

2. The on-axis, transmissive damage threshold automated measurement system of claim 1, wherein, The slider adjustment structure comprises: a stainless steel connecting rod (13), a first slider (11) and a second slider (12) which can slide on the stainless steel connecting rod (13) and can be locked on the stainless steel connecting rod (13). The test step comprises:

3. A measurement method based on the coaxial transmission type damage threshold automatic measurement system according to claim 2, characterized in that, firstly, the computer (10) is used to control the electric filter wheel (30) to insert a filter into a light path, control the laser to emit one pulse, and synchronously record the energy and the transmission spot, at this time, the light is weak light transmission; then, the electric filter wheel (30) is controlled to be turned to the position of the empty light transmission hole, the laser (20) is controlled to emit one or more pulses to cause damage, and the pulse energy is recorded, at this time, the light is strong light transmission; then, the above weak light transmission step is repeated, the transmission spot and the pulse energy of the weak light after the sample is damaged are measured once again, one cycle of the weak-strong-weak mode is completed, and one point of measurement is completed; the relative position of the sample is moved by controlling the two-dimensional translation table, and the test point is repeated. ​ Finally, the difference between the two weak light transmission spots is compared based on the overall transmittance criterion and the spot morphology criterion.

4. The measurement method of claim 3, wherein, The test step further includes a preparation stage, which includes: Confirming the connection of the system components and debugging the control on-off; By measuring the transmitted pulse energy of the sampling mirror (40) E T to the sampling pulse energy E S ratio r ST , the transmitted pulse energy is calibrated using the sampling pulse energy, i.e. E T = r ST E S ; Adjusting the first slider (11) and the second slider (12) to make the sample surface close to the vicinity of the focal point; Placing the knife blade on the light window of the two-dimensional translation stage and measuring the size of the focused spot using the knife-edge method; The quotient of the pulse energy and the spot area is the pulse energy density.

5. The measurement method of claim 4, wherein, The test step further includes a collection stage, which includes: Step S1: using the computer (10) to control the electric filter wheel (30) to emit a weak light pulse, and synchronously collecting the sample pulse energy data Ew0 through the energy meter; Step S2: collecting the spot photo Im0 projected on the conversion screen or white screen through the CMOS camera (110); Step S3, control the electric filter wheel (30) to emit 1 or S strong light pulses, record E S and calculate pulse energy data E T ; wherein the pulse energy data E T In the single pulse case it is a number, while in the multi-pulse case it is an array of 1 x S, i.e. corresponding to 1 vs 1 or S vs 1 tests; Step S4: finally, controlling the electric filter wheel (30) to emit a weak light pulse, collecting the sample pulse energy data Ew1 through the energy meter (50), and collecting the spot photo Im1 projected on the conversion screen through the CMOS camera (110).

6. The measurement method of claim 5, wherein, Further including: After completing the measurement of one point by the steps S1 to S4, using the computer (10) to control the two-dimensional translation stage to move the sample to the next point to be measured, and again completing the steps S1 to S4; The number of point measurements is any number between 50 and 100.

7. The method of measuring of claim 6, wherein, Further including: a data processing stage, which includes: Through edge detection and open-close operation image processing of the spot photos Im0 and Im1, the Euler number, the standard second-order central moment major and minor axes of the spot, and the ratio of the integral gray value of the spot photos Im0 and Im1 to the sample pulse energy data Ew0 and Ew1 are calculated.

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