Laser morphology measuring device based on hollow scanning probe method

Abstract

The invention discloses a laser morphology measuring device based on a hollow scanning probe method, and belongs to the technical field of high-energy laser measurement. The device comprises a rotating part, a front-back translation part and a vertical translation part, the front-back translation part is of a hollow structure, and the rotating part is located in the hollow structure; laser passes through the rotating part, is collected by a hollow scanning probe of the rotating part, and then enters the front-back translation part; the rotating part drives the hollow scanning probe to rotate; the front-back translation part drives the hollow scanning probe to translate front and back; and the vertical translation part is connected with the front-back translation part and drives the front-back translation part to vertically translate. According to the invention, the sampling precision and the testing efficiency of the high-energy focusing laser spot are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-energy laser measurement, and particularly relates to a laser topography measurement device based on a hollow scanning probe method. Background Art

[0002] High-energy focused lasers play an important role in fields such as processing, manufacturing, and welding. The typical focused spot diameter ranges from hundreds of micrometers to millimeters. The quality of high-energy focused lasers directly affects the performance of the lasers. It is urgent to evaluate parameters such as the beam quality factor, spot diameter, spot intensity distribution, beam width, focal position, beam parameter product, and beam focusing characteristics. A measurement device that can efficiently and stably measure the characteristics of high-energy focused lasers is crucial for improving the application of lasers.

[0003] For high-energy laser beam quality test systems, mainly measurement methods such as the CCD detector attenuation measurement method, the drum-type laser measurement method, and the hollow probe scanning sampling measurement are used.

[0004] The CCD detector attenuation measurement method is an indirect measurement method. It often uses attenuation and beam splitting methods to attenuate the high-energy laser power and energy to a range below the detector threshold, and converts the optical signal into an electrical signal through the detector for measurement. However, the CCD attenuation detection method cannot directly detect strong lasers. It is necessary to greatly split or attenuate the incident laser to a range below the detector threshold. The accuracy of beam splitting and attenuation directly affects the entire measurement system. In an actual built test system, due to environmental or other factors, it is impossible to ensure a stable and consistent beam splitting and attenuation ratio. At the same time, for high-power attenuation and beam splitting, the nonlinearity of the test system cannot be guaranteed either, and the test accuracy of the spot topography is relatively low. In addition, the CCD attenuation detection method can only measure the topography of the laser beam at the same position each time, and multiple tests at different positions are required to calculate laser parameters such as the beam waist and divergence angle.

[0005] The drum-type laser measuring instrument uses a drum-type structure for measurement. The laser irradiates the positions of small holes distributed in a spiral. After passing through the small holes, it is focused on the detector through a lens. By rotating the drum, multiple scanning bands can be obtained, and then the power density distribution of the entire beam can be measured. However, this measurement method cannot perform real-time measurement and cannot be used to measure the focused spot.

[0006] The hollow probe scanning method uses a micro mirror to reflect a small part of a large laser beam spot for detection. By rotating the sampling probe and moving the detector forward and backward, two-dimensional distributions of the corresponding laser intensity and power density are sampled. This method can measure the power density distribution of high-power laser beams. However, the probe scanning sampling method can only measure the morphology of the same position of the laser beam each time. Multiple tests at different positions are required to calculate laser parameters such as the beam waist and divergence angle. The operation is complex, resulting in a decrease in measurement accuracy. At the same time, there is a phenomenon of damaging the scanning probe when measuring the high-energy laser focusing spot of ten thousand watts. The current test device does not have a position feedback device and cannot meet the test requirements of small laser spots.

[0007] Therefore, it is extremely urgent to design a scanning measurement device for online real-time measurement of laser morphology. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides a laser morphology measurement device based on the hollow scanning probe method. The high-energy laser to be detected passes through the scanning probe and the mirror, and the optical signal is reflected to the detector. By controlling the movement of the scanning probe through three-dimensional movements such as rotation, forward and backward translation, and vertical translation, real-time online measurement of the position, intensity, beam quality, etc. of the entire laser is achieved.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A laser morphology measurement device based on the hollow scanning probe method includes a rotating part, a forward and backward translation part, and a vertical translation part. Among them,

[0011] The forward and backward translation part is of a hollow structure, and the rotating part is located inside the hollow structure;

[0012] The laser enters the rotating part through the forward and backward translation part and is collected by the hollow scanning probe of the rotating part; the rotating part drives the hollow scanning probe to rotate; the forward and backward translation part drives the hollow scanning probe to translate forward and backward;

[0013] The vertical translation part is connected to the forward and backward translation part and drives the forward and backward translation part to translate vertically.

[0014] The beneficial effects of the present invention are as follows:

[0015] By rotating, translating forward and backward, and translating vertically the scanning probe, the present invention realizes real-time online full-automatic measurement of the position, intensity, beam quality, etc. of the entire laser, improving the sampling accuracy and test efficiency of the high-energy focused laser spot.

[0016] An inert gas can be introduced into the device of the present invention to prevent the generation of plasma during the high-energy laser test, which not only reduces the damage of the high-energy focused laser to the surface material of the probe, but also increases the measurable maximum power density range.

[0017] The rotation and translation mechanisms in the device of the present invention are provided with high-precision position feedback sensors, which greatly improve the position accuracy of the platform and meet the test requirements for the morphology of micro-light spots. Brief Description of the Drawings

[0018] Figure 1 is a sectional view of a laser morphology measurement device based on a hollow scanning probe method of the present invention;

[0019] Figure 2 is a schematic diagram of the detailed structure of the rotating part.

[0020] Reference Signs:

[0021] 1 - laser to be measured; 2 - micro-hole; 3 - first reflector; 4 - hollow scanning probe; 5 - second reflector; 6 - turntable; 7 - sampling port; 8 - front-back translation stage; 9 - front-back translation guide rail; 10 - quick-insert gas inlet; 11 - front-back translation motor; 12 - circuit board; 13 - vertical translation motor; 14 - gear belt; 15 - housing; 16 - vertical translation guide rail; 17 - vertical translation lead screw; 18 - vertical translation stage; 19 - front-back translation lead screw; 20 - rotation motor; 21 - photodetector. Detailed Embodiments

[0022] The present invention will be further described below with reference to the drawings and embodiments.

[0023] Refer to Figure 1 , the present invention provides a laser morphology measurement device based on a hollow scanning probe method. The working principle is that the laser to be measured 1 is sampled through the micro-hole 2 at the tip of the hollow scanning probe 4, and then reflected by multiple reflectors inside the hollow scanning probe 4, and the optical signal is reflected to the photodetector 21. By rotating, translating forward and backward, and translating vertically the hollow scanning probe 4, real-time online measurement of the position, intensity, beam quality, etc. of the entire laser can be achieved; specifically, it includes a rotating part, a front-back translation part, and a vertical translation part. Among them,

[0024] The rotating part is fixed inside the front-back translation part, and includes a hollow scanning probe 4, a turntable 6, and a rotation motor 20. Among them, a first reflector 3 is arranged inside the hollow scanning probe 4 for reflecting the laser after it enters the micro-hole 2 at the front end of the hollow scanning probe 4 and then propagating in the hollow cavity through the first reflector 3. A second reflector 5 is arranged inside the turntable 6 for reflecting the light of the first reflector 3 to the photodetector 21; the rotation motor 20 drives the turntable 6 to rotate at a high speed through a gear belt;

[0025] The front-to-back translation part includes a photoelectric detector 21, a front-to-back translation stage 8, a front-to-back translation lead screw 19, two front-to-back translation guide rails 9, a linear bearing, a trachea quick-plug (including a quick-plug air inlet 10), and a front-to-back translation motor 11; the interior of the front-to-back translation part is close to a closed space, a sampling port 7 is set at the head end of the front-to-back translation stage 8, and a trachea quick plug is installed at the tail end. Inert gas can enter from the quick-plug air inlet 10 and be discharged from the sampling port 7 to avoid plasma generation during high-energy laser irradiation, which may cause damage to the hollow scanning probe 4. The two ends of the translation lead screw 19 are respectively fixedly connected to the front-rear translation stage 8 and the vertical translation stage 18, and the two ends of the front-rear translation guide rail 9 are respectively slidably connected to the front-rear translation stage 8 and the vertical translation stage 18. The front-rear translation lead screw 19 is driven by the front-rear translation motor 11 on the vertical translation stage 18, and the front-rear translation lead screw 19 drives the front-rear translation stage 8 to move forward and backward along the direction of the front-rear translation guide rail 9; the photoelectric detector 21 is installed on the front-rear translation stage 8 at a position corresponding to the turntable 6, and is located in the reflection light path to realize optical signal detection;

[0026] The vertical translation part includes a vertical translation stage 18, a vertical translation lead screw 17, a lead screw nut, two vertical translation guide rails 16, a linear bearing, a vertical translation motor 13, a gear belt 14, and a housing 15. The front and rear translation parts are fixed on the vertical translation stage 18. The vertical translation lead screw 17 is fixedly connected to the vertical translation stage 18. The two vertical translation guide rails 16 are slidingly connected to the vertical translation stage 18. Both ends of the vertical translation lead screw 17 and the two ends of the vertical translation guide rails 16 are connected to the housing 15. One end of the vertical translation lead screw 17 is also connected to the vertical translation motor 13 through the gear belt 14. The vertical translation motor 13 can realize the vertical movement of the vertical moving stage 18 along the direction of the vertical translation guide rail 16, thereby realizing the characteristic parameters of the test light beam at different positions. The lead screw nut is connected to the vertical translation lead screw 17 and the vertical translation platform 18 respectively, and the linear bearing is connected to the vertical translation guide rail 16 and the vertical translation platform 18 respectively. By rotating the vertical translation lead screw 17, the vertical translation platform 18 can be driven to move up and down along the vertical translation guide rail 16.

[0027] The hollow scanning probe 4 has a hollow structure inside, and the probe cover and inner cavity surface are plated with gold or silver, but not limited to gold and silver. A microhole 2 with a diameter of more than ten μm to one hundred μm is opened at the tip of the probe. The high-energy focused laser to be measured is sampled through the microhole 2. A miniature first reflector 3 (mirror / diffuse / scattering) is installed directly below the microhole 2. After the laser passes through the microhole 2, it is reflected by the first reflector 3 and propagates in the hollow to reach the second reflector 5. The light is further compensated by the attenuation lens. Finally, the high-energy focused laser to be measured is converted into low-intensity light as the output light signal to be measured to the subsequent photoelectric detector 21.

[0028] The hollow scanning probe 4 is installed on the circumference of the circular turntable 6. A second reflector 5 is installed inside the turntable 6, and the sampled laser can propagate in a specified direction inside the turntable 6, such as reaching the photodetector 21 after passing through the second reflector 5. Gears and bearing fittings are installed above the turntable 6. The inner and outer rings of the bearing are respectively fixed to the turntable 6 and the front and rear translation stages 8. During the rotation of the turntable 6, the direction of laser transmission can remain unchanged.

[0029] The inner part of the front and rear translation section is of a hollow structure. The bottom cover is fixed under the front and rear translation stage 8 to make the hollow close to being closed. The rotating part is fixed inside the hollow through a bearing. The photodetector 21 is installed directly above the front and rear translation stage 8 at the position where the laser passes, facilitating the reception of the sampled signal. The rotation motor 20 is installed above the front and rear translation stage 8 and is connected to the gear of the rotating part through gears and a belt to drive the rotating part to perform rotational scanning. A small window is opened at the front end position of the front and rear translation stage 8 as the sampling port 7, and the hollow scanning probe 4 can pass through here during rotation. The two rear ends on both sides of the front and rear translation stage 8 are connected to two front and rear translation guide rails 9, and a front and rear translation lead screw 19 is installed at the rear end in the middle. An air vent channel is machined inside one of the front and rear translation guide rails 9. One end of the front and rear translation guide rail 9 is connected to the hollow inside the front and rear translation stage 8, and the other end is installed with a quick connector for air intake. Inert gases such as nitrogen and argon are introduced, and the gas is discharged from the sampling port 7.

[0030] The housing 15 can be fixed by screws using metal plates. The front and rear covers can be removed to facilitate the installation and maintenance of parts. The vertical translation motor 13 is fixed on the top of the housing 15 and is connected to the gear on the vertical translation lead screw 17 inside the vertical translation section through a gear belt 14, which can drive the vertical translation stage 18 to move up and down. A lining plate is provided inside the housing 15 for installing and fixing the circuit board 12. A power socket, a data exchange interface (not limited to network port / DB9 / DB15), an air intake port, and a working indicator light are provided at the rear of the housing 15.

[0031] In summary, in the present invention, high-energy laser enters the inner cavity of the scanning probe rotating at high speed, is reflected by a mirror and enters a photodetector. The forward and backward translation motor drives the probe rotating at high speed through a forward and backward translation screw guide rail to first perform forward and backward translation, and then perform vertical translation. This cycle is repeated multiple times, thereby realizing the scanning of the characteristics of the position of the entire laser. Parameters such as intensity and beam quality can be obtained through a single test. It avoids the disadvantages of the traditional scanning device that requires multiple measurements and has low accuracy. At the same time, an inert gas ventilation device is added to avoid the generation of plasma during the irradiation of high-energy laser, increase the damage threshold of the probe, and can meet the measurement requirements of high-energy focused lasers with different powers and damage thresholds. Additionally, optionally, high-precision position feedback sensors can be installed in the rotation and translation mechanisms in the scanning device to improve the position accuracy of the platform. After installing a grating scale encoder sensor in the rotation mechanism, the accuracy can reach ±1 arc second, and the repeat positioning accuracy can reach ±0.1 arc second. After embedding position sensors such as grating scales in the translation mechanism, the accuracy can reach the level of ±1 micrometer, and the repeat positioning accuracy can reach ±0.3 micrometer, meeting the test requirements for the morphology of microspots.

[0032] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only specific embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A laser profile measurement device based on a hollow scanning probe method, characterized in that: It includes a rotating part, a front-to-back translation part, and a vertical translation part, wherein: The front-rear translation part is a hollow structure, and the rotation part is located in the hollow structure; The laser passes through the rotating part, is collected by the hollow scanning probe of the rotating part, and then enters the front-to-back translation part after reflection; the rotating part drives the hollow scanning probe to rotate; the front-to-back translation part drives the rotating part to translate back and forth; The vertical translation part is connected to the front-rear translation part and drives the front-rear translation part to translate vertically.

2. The laser profile measurement device based on the hollow scanning probe method according to claim 1, characterized in that: The forward and backward translation part includes a sampling port, the rotating part includes a microhole, the sampling port is arranged corresponding to the microhole, and the laser enters the microhole through the sampling port and is collected by the hollow scanning probe.

3. The laser profile measurement device based on the hollow scanning probe method according to claim 1, characterized in that: The rotating part includes a hollow scanning probe, a turntable, and a rotating motor, wherein the hollow scanning probe is installed below the circumference of the circular turntable, a bearing accessory is installed above the turntable, the inner and outer rings of the bearing accessory are respectively fixed to the turntable and the front and rear translation parts, and the rotating motor drives the turntable to rotate through a synchronous belt.

4. The laser profile measurement device based on the hollow scanning probe method according to claim 3, characterized in that: A second reflector is installed inside the turntable. After the laser is sampled by the microhole of the hollow scanning probe, it reaches the first reflector directly below the microhole and the second reflector inside the turntable in sequence, and is detected by the photoelectric detector.

5. The laser profile measurement device based on the hollow scanning probe method according to claim 4, characterized in that: The front-to-back translation part includes a front-to-back translation platform, a front-to-back translation lead screw, a front-to-back translation guide rail, a front-to-back translation motor and a photoelectric detector. The photoelectric detector is installed on the front-to-back translation platform and is used to receive the light signal reflected from the second reflector. The two ends of the front-to-back translation lead screw are respectively fixedly connected to the front-to-back translation platform and the vertical translation platform. The two ends of the front-to-back translation guide rail are respectively slidably connected to the front-to-back translation platform and the vertical translation platform. The front-to-back translation lead screw is driven by the front-to-back translation motor, and the front-to-back translation lead screw drives the front-to-back translation platform to move forward and backward along the direction of the front-to-back translation guide rail.

6. The laser profile measurement device based on the hollow scanning probe method according to claim 5, characterized in that: The vertical translation part includes a vertical translation platform, a vertical translation lead screw, a vertical translation guide rail and a vertical translation motor. The front and rear translation parts are fixed on the vertical translation platform. The vertical translation lead screw is fixedly connected to the vertical translation platform. The vertical translation guide rail is slidably connected to the vertical translation platform. The vertical translation motor is used to realize the vertical movement of the vertical translation platform along the direction of the vertical translation guide rail.

7. The laser profile measurement device based on the hollow scanning probe method according to claim 3, characterized in that: Gears and bearing accessories are installed above the turntable, and the inner and outer rings of the bearings are fixed to the turntable and the front and rear translation stages respectively. During the rotation of the turntable, the direction of laser transmission remains unchanged.

8. The laser profile measurement device based on the hollow scanning probe method according to claim 6, characterized in that: A sampling port is arranged at the front end of the front and rear translation platform, and a quick-insert air inlet is arranged at the rear end. Inert gas enters through the quick-insert air inlet and is discharged from the sampling port.

9. The laser profile measurement device based on the hollow scanning probe method according to claim 7, characterized in that: Both ends of the vertical translation lead screw and both ends of the vertical translation guide rail are connected to the housing, and one end of the vertical translation lead screw is connected to the vertical translation motor through a gear belt.

10. The laser profile measurement device based on the hollow scanning probe method according to claim 9, characterized in that: The shell is formed by fixing metal plates by screws, and an inner lining plate is arranged inside the shell for installing and fixing the circuit board. A power socket, a data exchange interface, an air inlet and a working indicator light are arranged at the rear of the shell.

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