High-precision strong laser power characteristic measuring system

Abstract

The invention discloses a high-precision strong laser power characteristic measurement system, which comprises a light power detection module, a photo-thermal detection module and equipment, the light force detection module comprises a closed black box, and a high-reflection mirror group and a weighing sensor which are arranged in the closed black box; the high-reflection mirror group comprises a first reflection mirror, a second reflection mirror and a third reflection mirror; a light inlet and a light outlet are formed in the two sides of the closed black box respectively, and the weighing sensor is arranged below the second reflecting mirror and used for obtaining the high-precision light force quality when the laser beam passes through the second reflecting mirror; and the light force detection module is arranged on a light path of a light outlet of the light force detection module. According to the invention, the optical power detection module and the photo-thermal detection module are successively arranged on one optical path, so that cooperative power measurement can be realized; and high-accuracy measurement of strong laser power in a range higher than 1.5 KW is realized through the light power detection module. According to the method, the instantaneous and average power of the laser can be measured, and stable long-time light emitting detection can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of optical measurement, and in particular to a high-precision strong laser power characteristic measurement system. Background Art

[0002] At present, with the development of laser technology, laser energy continues to break through the saturation threshold of photoelectric power meters. Therefore, photothermal power meters that can measure high power have emerged. This type of power meter probe absorbs energy under laser irradiation and measures power by increasing the temperature of the thermoelectric sensor in the probe. Based on the design principles of the thermal effect of lasers and the thermoelectric effect of metals, this power measurement method has the advantages of flat spectral response, relatively difficult to reach saturation, and relatively small influence by the angle and position of light. It can obtain accurate measurement results under conventional laser energy. However, under strong laser energy, the accumulation of laser thermal effect is high, resulting in reduced measurement accuracy; the thermal effect accumulation time is long, and the problem of slow response is prominent. This greatly restricts the application of this power characteristic measurement method in the field of high-intensity lasers.

[0003] In view of the need for accurate detection of the power of strong lasers, the current detection methods mainly have the following problems:

[0004] (1) Insufficient accuracy. At present, the power detection unit material is easily damaged by strong lasers, and the coupling coefficient will change, which will eventually lead to a detection accuracy greater than 5%, which is significantly lower than the conventional laser power measurement accuracy.

[0005] (2) Lack of means to detect instantaneous characteristics. Strong lasers have outstanding damage, impact, and cutting capabilities, and the operation time is generally within a few seconds. However, the current power measurement equipment requires a certain amount of time for thermal effects to accumulate, so it is impossible to measure instantaneous power, laser stability during operation and other characteristics.

[0006] (3) Lack of means to detect dynamic characteristics. Limited by the working mode that requires thermal effect accumulation, high-power lasers can only carry out static power measurement when the operation is stopped in the industrial field, processing and measurement applications, and lack the means to detect dynamic parameters such as online power characteristics.

[0007] Traditional high laser energy detection methods are mostly designed based on the thermal effect of light. For strong lasers, not only is the surface of the absorbing material easily damaged by the laser, but the properties of the absorbing material are also easily changed, which ultimately reduces the measurement accuracy and sensitivity, limiting the upper limit of laser energy that can be detected by this method. Summary of the invention

[0008] The purpose of the present invention is to provide a high-precision high-intensity laser power characteristic measurement system, which can realize the far-field power density and spot distribution measurement function, the laser instantaneous / average power measurement function, the light emission time measurement function and the power stability, so as to provide technical support for the high-intensity laser effect.

[0009] The technical solution adopted by the present invention is:

[0010] A high-precision high-intensity laser power characteristic measurement system comprises a light force detection module, a light heat detection module and a device; the light force detection module comprises a sealed black box and a high-reflection mirror group and a weighing sensor arranged in the sealed black box, the high-reflection mirror group comprises a first reflector, a second reflector and a third reflector; a light inlet and a light outlet are respectively arranged on both sides of the sealed black box, the first reflector is used to reflect the light beam entering the light inlet to the second reflector, the third reflector is used to reflect the light reflected by the second reflector to the light outlet, and the weighing sensor is arranged below the second reflector to obtain the high-precision light force quality of the laser beam when passing through the second reflector; the light force detection module is arranged on the optical path of the light outlet of the light force detection module, and is used to perform nested measurement on the laser, that is, to obtain the power value without consuming light energy; the cooling device is connected to the light heat detection module, and is used to ensure that the high heat generated by the light heat detection module when absorbing the tail light is taken away.

[0011] The photothermal detection module adopts a 15K-W-BB-45 photothermal detector.

[0012] The transmittance of the light inlet and light outlet of the sealed black box is higher than 99.8%, the reflectivity of the high reflector group is higher than 99.98%, and the installation angles of the first reflector, the second reflector and the third reflector are 35°, 0° and 35° respectively.

[0013] The materials of the reflective film used in the high-reflection mirror group are mainly ZnS, YbF3, and Ge. The coating processes of the three materials are locked from the perspective of the multi-layer film system to obtain the basic performance parameters of the materials; on this basis, the multi-layer film structure is optimized to achieve high reflection of the medium and long wave spectrum, and the maximum damage resistance threshold can reach 95.5KW / cm2.

[0014] The resolution of the weighing sensor is 10 μg.

[0015] It also includes a temperature sensor, an electric heating module, a semiconductor refrigeration module and a controller. The temperature sensor is used to detect the ambient temperature, and its output end is connected to the input end of the controller. The control input ends of the semiconductor refrigeration module and the electric heating module are respectively connected to the output end of the controller for controlling the start and stop, thereby maintaining the ambient temperature of the light force detection module.

[0016] It also includes a heat-insulating layer, which is arranged to cover the outside of the light force detection module.

[0017] The cooling device is a water cooler.

[0018] The present invention can achieve coordinated power measurement by successively setting up a light force detection module and a light heat detection module on an optical path; the light force detection module is used to achieve high-accuracy measurement of strong laser power in the range of more than 1.5KW, and the light heat detection module is used to measure and absorb the tail light in the range of 0W-1.5KW. The liquid cooling device not only ensures accurate measurement results, but also is used to process the heat of strong laser radiation to ensure equipment safety. The instantaneous and average power of the laser can be measured by the method of the present invention, and long-term light emission detection can be performed stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a system principle block diagram of the present invention;

[0021] Figure 2 is a flow chart of the measurement system of the present invention;

[0022] Figure 3 This is a schematic diagram of the structure of the optical force detection module described in the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] like Figure 1 , 2As shown in 3, the present invention includes an optical force detection module, an optical thermal detection module and a cooling device; the optical force detection module includes a sealed black box and a high-reflection mirror group and a weighing sensor arranged in the sealed black box, and the high-reflection mirror group includes a first reflector, a second reflector, and a third reflector; a light inlet and a light outlet are respectively arranged on both sides of the sealed black box, the first reflector is used to reflect the light beam entering the light inlet to the second reflector, and the third reflector is used to reflect the light reflected by the second reflector to the light outlet, and the weighing sensor is arranged under the second reflector to obtain the high-precision optical force quality when the laser beam passes through the second reflector; the optical force detection module is arranged on the optical path of the light outlet of the optical force detection module, and is used to perform nested measurement on the laser, that is, to obtain the power value without consuming light energy; the cooling device is connected to the optical thermal detection module, and is used to ensure that the high heat generated by the optical thermal detection module when absorbing the tail light is taken away.

[0026] In the optical force detection module described in the present application, in actual use, the energy and momentum of a single photon can be expressed as:

[0027]

[0028]

[0029] In the formula is Planck's constant, v is the photon frequency, and c is the speed of light in vacuum.

[0030] The number of photons contained in a laser with power P per unit time Δt can be expressed as:

[0031]

[0032] The force generated by the laser can be expressed as:

[0033]

[0034] Where P is the laser power, c is the speed of light in vacuum, θ is the incident angle, R is the reflectivity, and A is the absorptivity.

[0035] This tiny light pressure is equivalent to the gravity generated by placing an object with a tiny mass m on the reflector.

[0036]

[0037] As long as the relationship between laser power and this light pressure is obtained, the laser power can be characterized by quality.

[0038] The actual layout of the present invention is as follows Figure 2As shown, the laser continuously passes through the photoforce-photothermal power measurement system to achieve collaborative power measurement. The photoforce detection module achieves high-accuracy measurement of strong laser power above 1.5KW; the photothermal detection module is used to measure and absorb the tail light in the 0W-1.5KW range. The liquid cooling device not only ensures accurate measurement results, but also is used to process the heat of strong laser radiation to ensure equipment safety. This method can measure the instantaneous and average power of the laser, and can stably detect long-term light output.

[0039] Figure 3 This is the schematic diagram of the measuring device. After the incident light beam enters the sealed black box, it passes through the optical path system composed of three reflectors and is emitted in the original direction. Only the light beam energy distribution is rotated 180 degrees along the optical axis. Among them, the transmittance of the light inlet and light outlet of the sealed black box is higher than 99.8%, the reflectivity of the high reflector group is higher than 99.98%, and the installation angles of the first reflector, the second reflector, and the third reflector are 35°, 0°, and 35°, respectively. For medium and long-wave infrared strong lasers, the materials of the reflective film used in the high reflector group are mainly ZnS, YbF3, and Ge. From the perspective of the multilayer film system, the coating process of the three materials is locked to obtain the basic performance parameters of the materials; on this basis, the multilayer film structure is optimized to achieve high reflection of the medium and long-wave spectrum, and the maximum damage resistance threshold can reach 95.5KW / cm2.

[0040] A weighing sensor is installed under the second reflector, which can sensitively display the optical force effect. Its resolution reaches 10μg, and because the box is sealed and clean, the environmental influence of air flow and dust is eliminated, and the high-precision optical force quality of the laser beam passing through the reflector can be obtained. For example, when the incident power is 0.1KW~15KW, the pressure generated by the laser can be equivalent to the gravity generated by an object with a mass of 0.067mg~10.05mg, so the optical force detection module in the present invention can achieve high-precision measurement of strong lasers.

[0041] The photothermal detection module adopts the 15K-W-BB-45 model, which can accurately measure the laser power in the range of 0 to 1.5KW, with a measurement error of no more than 3%. It is also equipped with a liquid cooling device to accurately control the temperature of the probe's illuminated surface to ensure the reliability of the equipment.

[0042] The temperature control design module includes a temperature sensor, an electric heating module, a semiconductor refrigeration module and a controller. The temperature sensor is used to detect the ambient temperature, and its output end is connected to the input end of the controller. The control input ends of the semiconductor refrigeration module and the electric heating module are respectively connected to the output end of the controller to control the start and stop, thereby maintaining the ambient temperature of the light force detection module. It also includes a thermal insulation layer, and the thermal insulation layer is coated on the outside of the light force detection module. For the light force detection module, the present invention adopts a structural design of temperature measurement, electric heating film, semiconductor refrigeration and thermal insulation layer, and the specific logic is as follows:

[0043] 1) When the ambient temperature is lower than 15°C, the electric heating film automatically starts heating and stops heating when the temperature of the optical pressure measurement module reaches 20°C.

[0044] 2) When the ambient temperature is between 15°C and 25°C, the temperature of the optical pressure measurement module is maintained at the ambient temperature.

[0045] 3) When the ambient temperature is higher than 25°C, the semiconductor refrigeration starts automatically, and the refrigeration stops when the temperature of the optical pressure measurement module reaches 20°C.

[0046] For the photothermal detection module, an external liquid cooler design is adopted. The cooling device adopts a water cooler. In actual use, the liquid cooler is set to 23°C, and the cooling capacity reaches 5.2KW. When working, the coolant circulates through the probe to take away the high heat generated when the tail light is absorbed, ensuring the safety of the equipment and the effective treatment of the tail light.

[0047] The force effect of light refers to the fact that photons have kinetic mass and momentum, and when they collide with an object, they produce slight non-destructive deformation, and at the same time, they scatter, absorb, reflect and other wave characteristics. The particle characteristics are reflected in the momentum exchange between photons and matter. Momentum exchange will produce radiation pressure, so accurate detection of radiation pressure can obtain the corresponding power value. This method has the advantages of small size, light weight, and fast response speed. It can be connected in series into the optical system without energy loss. The higher the laser energy, the better the signal-to-noise ratio of the measurement result. Therefore, it has obvious advantages when measuring strong lasers.

[0048] Since the application scopes of the two power measurement methods are complementary, the photoforce-photothermal power measurement system of the present invention can ensure response speed and detection accuracy when measuring strong laser power.

[0049] The present invention has a new dynamic embedding capability. According to the needs of use, a single or multiple optical force detection modules can be embedded in any position of the optical system. Without consuming the laser energy of the original optical system and changing the direction of the light beam, the research on online power characteristics can be carried out. This is of great significance for real-time monitoring of high-power laser systems, early warning of mirror damage, and optical performance diagnosis. The laser measurement mode uses an optical pressure measurement unit to measure the instantaneous power of the laser far field, the average power of the laser far field, the laser light emission time, and the stability of the laser power.

[0050] The present invention can improve the laser power detection range through the above structure. The surface of the absorbing material of the traditional laser power measurement equipment is easily scratched when facing a strong laser, and the sampling method is also easy to change the sampling ratio under the action of high temperature, which restricts the application of the traditional method for high laser power detection. The photodynamic-photothermal power measurement system is not affected by the laser energy intensity. The equipped liquid cooling device can maintain a constant temperature (23°C) to ensure the normal operation of the equipment under strong laser conditions. As long as the reflector material of the photodynamic detection module can withstand the laser energy intensity, theoretically, the scope of use of the present invention is not restricted by the laser power.

[0051] Furthermore, the present invention can also improve the detection accuracy and response speed of laser power; the present invention can give play to the advantages of different devices, and take the reading results of the photothermal detection module at 0-1.5KW. Since it belongs to the conventional energy range, its measurement accuracy is 2%; when it is higher than 1.5KW, the reading results of the photoforce detection module are taken, and the measurement accuracy is 3%. On the whole, the measurement accuracy of the present invention is controlled within 3% during the energy growth process of conventional-strong laser. At the same time, the photothermal detection module can respond quickly within 3s under conventional laser conditions and the photoforce detection module can respond quickly within 3s under strong laser conditions. Compared with the traditional laser energy detection method that requires long-term stable readings when applied to strong lasers, the power measurement responsiveness of the present invention is significantly improved, and the instantaneous power in the power characteristics can be efficiently obtained.

[0052] The present invention can also capture the dynamic characteristics of laser power. Traditional power measurement equipment, such as photoelectric and calorimetric types, need to consume all the energy of the laser in order to accurately obtain laser power parameters. Therefore, traditional equipment can only carry out static measurements and can only be fixed at the tail end of the optical system or in the non-operating state of the optical system. This restricts the observation of the power characteristics of the operating state of the optical system in principle. The present invention has a new dynamic embedding capability, and can embed a single or multiple optical force detection modules into any position of the optical system according to the needs of use. It can carry out research on online power characteristics without consuming the laser energy of the original optical system and changing the direction of the light beam. This is of great significance for real-time monitoring of high-power laser systems, early warning of mirror damage, and optical performance diagnosis.

[0053] The following is a test and evaluation of key indicators, the uncertainty of the photo-thermal power measurement system;

[0054] Table 1 Uncertainty test results under different power conditions

[0055]

[0056] It can be seen from Table 1 that for incident lasers of different powers, the uncertainty of the photoforce-photothermal power measurement system is within 3%, which is better than the mainstream high laser energy detection equipment on the market.

[0057] Measurement of response speed: The response speed of the light force detection module can theoretically reach ms level. In actual experiments, the reading of the light pressure measurement device can be stable after 3s. The rising edge and falling edge are the response time of the light force detection module.

[0058] Therefore, compared with the traditional power measurement method that only relies on light and heat accumulation: the higher the laser energy, the more time is needed for heat accumulation, resulting in a lower response speed. The present invention solves the problem of low response speed in principle and can obtain parameters with evaluation value such as instantaneous power and light output stability of the laser.

[0059] After collecting laser light based on the high-precision optical pressure measurement system, the high-precision pressure sensor completes data collection; based on the collected optical pressure information, the power parameters are quickly calculated through the pressure-to-power formula; the thermal detection module completes the high-power absorption of the thermal tail light, and takes away the heat through the water cooling device. Based on the host computer control software, the power, average power, power stability and other measurements are completed.

[0060] In the description of the present invention, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like, indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific protection scope of the present invention.

[0061] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0062] Note that the above are only preferred embodiments of the present invention and the principles of the application technology. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the specific embodiments described herein, and may include more other effective embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A high-precision high-intensity laser power characteristic measurement system, characterized in that: It comprises an optical force detection module, an optical heat detection module and equipment; the optical force detection module comprises a sealed black box and a high reflector group and a weighing sensor arranged in the sealed black box, the high reflector group comprises a first reflector, a second reflector and a third reflector; a light inlet and a light outlet are respectively arranged on both sides of the sealed black box, the first reflector is used to reflect the light beam entering from the light inlet to the second reflector, the third reflector is used to reflect the light reflected by the second reflector to the light outlet, and the weighing sensor is arranged under the second reflector to obtain the high-precision optical force quality when the laser beam passes through the second reflector; the optical force detection module is arranged on the optical path of the light outlet of the optical force detection module, and is used to perform nested measurement on the laser, that is, to obtain the power value without consuming light energy; the cooling device is connected to the optical heat detection module, and is used to ensure that the high heat generated when the optical heat detection module absorbs the tail light is taken away.

2. The high-precision high-intensity laser power characteristic measurement system according to claim 1, characterized in that: The photothermal detection module adopts a 15K-W-BB-45 photothermal detector.

3. The high-precision high-intensity laser power characteristic measurement system according to claim 2, characterized in that: The transmittance of the light inlet and light outlet of the sealed black box is higher than 99.8%, the reflectivity of the high reflector group is higher than 99.98%, and the installation angles of the first reflector, the second reflector and the third reflector are 35°, 0° and 35° respectively.

4. The high-precision high-intensity laser power characteristic measurement system according to claim 3, characterized in that: The materials of the reflective film used in the high-reflection mirror group are mainly ZnS, YbF3, and Ge. The coating processes of the three materials are locked from the perspective of the multi-layer film system to obtain the basic performance parameters of the materials; on this basis, the multi-layer film structure is optimized to achieve high reflection of the medium and long wave spectrum, and the maximum damage resistance threshold can reach 95.5KW / cm2.

5. The high-precision high-intensity laser power characteristic measurement system according to claim 1, characterized in that: The resolution of the weighing sensor reaches 10 μg.

6. The high-precision high-intensity laser power characteristic measurement system according to any one of claims 1 to 5, characterized in that: It also includes a temperature sensor, an electric heating module, a semiconductor refrigeration module and a controller. The temperature sensor is used to detect the ambient temperature, and its output end is connected to the input end of the controller. The control input ends of the semiconductor refrigeration module and the electric heating module are respectively connected to the output end of the controller for controlling the start and stop, thereby maintaining the ambient temperature of the light force detection module.

7. The high-precision high-intensity laser power characteristic measurement system according to claim 6, characterized in that: It also includes a heat-insulating layer, which is arranged to cover the outside of the light force detection module.

8. The high-precision high-intensity laser power characteristic measurement system according to claim 7, characterized in that: The cooling device is a water cooler.

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