High speed beam quality analyzer

Abstract

The utility model relates to high -intensity laser testing technical field discloses high -speed beam quality analysis appearance, in the utility model, along the light path direction places laser power attenuation device, no aberration focusing lens, polarization independent turning mirror group, light shutter, two -dimensional virtual image phase array standard tool group, big -area array camera and residual light light -receiving barrel in proper order. After the light beam of being measured passes two -dimensional virtual image phase array device, the distance of each virtual image on the two -dimensional virtual image array array formed is different and satisfies approximate arithmetic progression, to guarantee that big -area array camera measures the multiple light spots on the different transmission distance after no aberration focusing lens simultaneously, finally through the fitting of the hyperbola of partition image algorithm that represents the light beam quality, to obtain the light beam quality of the laser of being measured of current time. This method does not need real -time movement displacement platform, and the measurement speed mainly depends on the light shutter switch rate, camera sampling rate and host computer computing speed, has the high time -effect characteristic of data acquisition and analysis.

Description

Technical Field

[0001] This utility model relates to the field of high-brightness laser parameter testing technology, and more specifically to a high-speed beam quality analyzer. Background Technology

[0002] Fiber lasers, with their advantages of high beam quality, compact structure, and high energy conversion efficiency, have been widely used in industrial processing (such as laser cutting and welding), medical diagnosis and treatment (such as laser surgery), and military defense (such as laser ranging and defense). With the rapid iteration of technologies in these fields, the industry's requirements for laser beam quality are becoming increasingly stringent—beam quality directly determines the laser's effectiveness (such as processing accuracy, communication distance, and detection sensitivity). Therefore, accurate and real-time measurement of beam quality has become a key technological requirement.

[0003] The internationally recognized metric for evaluating the quality of high-brightness laser beams is the M² factor, defined as the ratio of the near-field and far-field characteristics of the test beam to that of an ideal Gaussian beam. Specifically specified in ISO standard 11146, it is a core performance parameter for light sources such as fiber lasers and solid-state lasers. Currently, the mainstream testing methods for the M² factor include: 1. Multi-position measurement method: This method characterizes the near-field characteristics and divergence properties of a beam by directly measuring the light spot and light field at multiple positions during beam propagation. It is a direct measurement method specified by ISO standards and has the highest measurement accuracy. 2. Liquid lens method: By adjusting the focal length of the liquid lens to simulate different transmission positions, the M² factor is indirectly calculated. This method is greatly affected by the accuracy of the lens refractive index adjustment. 3. Wavefront analysis method: Based on the wavefront information of the beam obtained by the wavefront detector, the M² factor is derived. It is an indirect measurement and is susceptible to interference from wavefront reconstruction algorithm errors. 4. Mode decomposition method: The M² factor is calculated by decomposing the mode components of the beam, but the measurement accuracy is low for complex mode beams.

[0004] Among these methods, the multi-position measurement method offers the highest accuracy but suffers from significant drawbacks. This method requires a CCD camera and a displacement platform to frequently move the folding mirror assembly or the CCD camera position to acquire beam spot information at different transmission locations. On one hand, it necessitates high-precision real-time displacement control components, increasing system complexity and cost. On the other hand, displacement adjustment and multiple sampling are time-consuming, failing to meet the real-time and continuous beam quality testing requirements of high-speed changing optical systems (such as pulsed lasers and dynamically Q-switched lasers).

[0005] Therefore, there is an urgent need for a high-speed beam quality analysis scheme that does not require real-time moving of the displacement platform and can simultaneously acquire beam spot information from multiple locations, in order to solve the timeliness and stability problems of existing multi-location measurement methods. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing multi-position measurement methods, which require real-time movement of the displacement platform, are time-consuming, and cannot be adapted to time-varying optical field systems. This invention provides a high-speed beam quality analyzer that enables synchronous acquisition and rapid analysis of optical field information at multiple positions, meets the requirements for instantaneous beam quality measurement, and improves test stability and data validity.

[0007] To achieve the above technical objectives, this utility model proposes a high-speed beam quality analyzer, comprising: a laser power attenuation device, an aberration-free focusing lens, a polarization-independent folding mirror group, an optical shutter, a two-dimensional virtual image phase array device, a large-area array camera, and a residual light collection barrel; the laser power attenuation device is used to attenuate the power of the beam to be measured, the aberration-free focusing lens is used to converge the beam to be measured, the polarization-independent folding mirror group is used for focal positioning of the light velocity to be measured, and the optical shutter is used to control the exposure time; After the laser under test passes through the two-dimensional virtual image phase array device, it forms a virtual image array composed of multiple virtual images arranged in two dimensions. The distance from each virtual image in the virtual image array to the photosensitive surface of the large-area array camera is different, and the distance from each row or column of virtual images in the virtual image array to the photosensitive surface of the large-area array camera is arranged in an approximately arithmetic sequence. The large-area array camera is used to record the light field intensity distribution of the two-dimensional virtual image array. The spot size of each virtual image on the large-area array camera is calculated by the partitioned image algorithm, and the beam quality of the laser to be tested at the current moment is calculated based on the relative difference in distance between each virtual image and the photosensitive surface of the large-area array camera. The residual light collection bucket includes a first residual light collection bucket and a second residual light collection bucket. The residual light collection bucket is used to collect residual light that has not entered the large-area array camera.

[0008] Furthermore, the two-dimensional virtual image phase array device includes a first virtual image phase array and a second virtual image phase array, which are placed orthogonally. The first virtual image phase array is used to generate a one-dimensional virtual image array in the x-direction, and the second two-dimensional virtual image phase array is used to generate a one-dimensional virtual image array in the y-direction.

[0009] Furthermore, both the first virtual image phase array and the second virtual image phase array are a glass plate with two parallel sides coated with a high-reflectivity film, or two parallel single-sided high-reflectivity glass plates.

[0010] Furthermore, the polarization-independent folding mirror assembly includes a first polarization-independent mirror, a second polarization-independent mirror, and a displacement platform. The displacement platform is used to adjust the optical path between the first polarization-independent mirror and the second polarization-independent mirror, so that the focal virtual image of the beam converged by the aberration-free focusing lens is located in the middle region of the photosensitive surface of the large-area array camera.

[0011] Furthermore, the displacement platform is an electrically adjustable displacement platform or a mechanical displacement platform.

[0012] Furthermore, the center-to-center distance between adjacent virtual images in the two-dimensional virtual image phase array group device is greater than 3 times the spot diameter of the laser to be tested.

[0013] Furthermore, the closing time of the optical shutter is adapted to the refresh cycle and background noise acquisition requirements of the large-area array camera. During the period when the optical shutter is closed, the large-area array camera performs refresh operation and background noise acquisition operation.

[0014] Furthermore, the operating band of the large-area array camera covers the wavelength of the laser to be tested, and the operating band includes the visible light band, the near-infrared band, or the mid-infrared band.

[0015] In summary, the technical solution proposed in this invention, compared with existing beam quality measurement solutions, can achieve at least the following beneficial effects: 1. High timeliness: The device realizes synchronous measurement of light spots at multiple positions through a two-dimensional virtual image phase array group, without the need for real-time movement of the displacement platform. The measurement speed depends only on the camera sampling rate and the host computing speed, which can meet the real-time monitoring requirements of the time-varying light field system. High stability: The displacement platform remains stationary during the measurement process, eliminating the need for real-time correction of the optical field center position, avoiding spot shift caused by displacement errors, and improving test repeatability and accuracy; High data validity: A large-area array camera can acquire spot information from multiple locations in a single measurement, resulting in a much larger amount of effective data than traditional single-location measurements, which is beneficial for raw data compression and subsequent analysis; System simplification: No need for high-precision real-time displacement control components, reducing system complexity and cost, while also reducing mechanical wear and extending equipment life. Attached Figure Description

[0016] This utility model will be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of a high-speed beam analyzer provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the light intensity distribution of the 5×1 output light spot after the virtual image phase array (5-1) in this embodiment of the present invention on the large-area array camera (6); Figure 3 This is a schematic diagram of the light intensity distribution of the 5×3 output light spot after the virtual image phase array (5-2) in this embodiment of the present invention on the large array camera (6).

[0017] Explanation of reference numerals in the attached figures: 1-Laser power attenuation device, 2-Aberration-free focusing lens, 3-Polarization-independent folding mirror group, 3-1 Polarization-independent reflector, 3-2 Polarization-independent reflector, 3-3 Displacement platform, 4-Optical shutter, 5-Two-dimensional virtual image phase array device, 5-1-First virtual image phase array, 5-2-Second virtual image phase array, 6-Large area array camera, 7-1-First residual light collection barrel, 7-2-Second residual light collection barrel. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. Therefore, the following detailed description of the embodiments of this utility model provided in the accompanying drawings is not intended to limit the scope of the claimed utility model, but merely to represent selected embodiments of this utility model.

[0019] In the description of this utility model, it should be understood that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0020] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0021] At least one exemplary embodiment is now provided in conjunction with the accompanying drawings. The detailed description of the exemplary embodiments provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate exemplary embodiments provided in the invention.

[0022] Example 1 like Figure 1 As shown, the high-speed beam quality analyzer includes: a laser power attenuation device 1, an aberration-free focusing lens 2, a polarization-independent folding mirror group 3, an optical shutter 4, a two-dimensional virtual image phase array group 5, a large-area camera 6, and a residual light collection barrel; the laser power attenuation device 1 is used to attenuate the power of the beam to be measured, the aberration-free focusing lens 2 is used to converge the beam to be measured, the polarization-independent folding mirror group 3 is used for focal positioning of the light velocity to be measured, and the optical shutter 4 is used to control the exposure time; After the laser to be tested passes through the two-dimensional virtual image phase array device 5, it forms a virtual image array composed of multiple virtual images arranged in two dimensions. The distance from each virtual image in the virtual image array to the photosensitive surface of the large-area array camera 6 is different, and the distance from each row or column of virtual images in the virtual image array to the photosensitive surface of the large-area array camera 6 is arranged in an approximately arithmetic sequence. The large-area array camera 6 is used to record the light field intensity distribution of the two-dimensional virtual image array. The spot size of each virtual image on the large-area array camera 6 is calculated by the partitioned image algorithm, and the beam quality of the laser to be tested at the current moment is calculated based on the relative difference in distance from each virtual image to the photosensitive surface of the large-area array camera 6. The residual light collection bins include a first residual light collection bin 7-1 and a second residual light collection bin 7-2. The residual light collection bins are used to collect residual light that has not entered the large-area array camera 6.

[0023] The laser power attenuation device 1 is used to attenuate the power of the test beam to the tens to hundreds of mW level, ensuring that the pixels of the large-area camera 6 are not overexposed or damaged, and that the device itself is free from thermal distortion. An aberration-free focusing lens converges the test beam, ensuring that at least ten pixels of the large-area camera 6 are covered within the diameter of the spot at the convergence point. The displacement platform 3-3 of the polarization-independent folding mirror group 3 is adjusted to position the focus of the converged beam near the center of the large-area camera 6, thus ensuring that the large-area camera 6 records spot information at multiple positions on both sides of the beam waist of the test beam. After passing through the two-dimensional virtual image phase array device 5, the test beam forms a two-dimensional virtual image array with different optical path differences. A residual light collector is used to collect residual light that does not enter the large-area camera 6. The large-area camera 6 simultaneously measures multiple spots at different transmission distances after passing through the aberration-free focusing lens 2, and finally, a hyperbola characterizing the beam quality is fitted using a partitioned image algorithm to obtain the current quality of the test laser beam.

[0024] Based on the multi-position measurement method, this invention enables simultaneous measurement of the light field at multiple positions, effectively shortening the measurement time and facilitating the measurement of real-time beam quality. Furthermore, during beam quality testing, the displacement platform 3-3 remains stationary, eliminating the need for real-time correction of the light field center position, thus promoting higher testing stability and faster data processing. Additionally, the large-area array camera 6 used in this invention generates more effective data in a single measurement, which is beneficial for compressing the raw data.

[0025] Furthermore, the two-dimensional virtual image phase array device 5 includes a first virtual image phase array 5-1 and a second virtual image phase array 5-2. The first virtual image phase array 5-1 and the second virtual image phase array 5-2 are placed orthogonally. The first virtual image phase array 5-1 is used to generate a one-dimensional virtual image array in the x direction, and the second two-dimensional virtual image phase array 5-2 is used to generate a one-dimensional virtual image array in the y direction.

[0026] Furthermore, both the first virtual image phase array 5-1 and the second virtual image phase array 5-2 are a glass plate with two parallel sides coated with a high-reflectivity film, or two parallel single-sided high-reflectivity glass plates.

[0027] Furthermore, the polarization-independent folding mirror group 3 includes a first polarization-independent mirror 3-1, a second polarization-independent mirror 3-2, and a displacement platform 3-3. The displacement platform 3-3 is used to adjust the optical path between the first polarization-independent mirror 3-1 and the second polarization-independent mirror 3-2, so that the focal virtual image of the light beam converged by the aberration-free focusing lens 2 is located in the middle region of the photosensitive surface of the large-area array camera 6.

[0028] Furthermore, the displacement platform 3-3 is an electrically adjustable displacement platform or a mechanical displacement platform.

[0029] In the two-dimensional virtual image phase array device, the center-to-center distance between adjacent virtual images is greater than 3 times the spot diameter of the laser beam to be tested.

[0030] Furthermore, the closing time of the optical shutter 4 is adapted to the refresh cycle and background noise acquisition requirements of the large-area array camera 6. During the period when the optical shutter 4 is closed, the large-area array camera 6 performs refresh operation and background noise acquisition operation.

[0031] Furthermore, the operating band of the large-area array camera 6 covers the wavelength of the laser to be tested, and the operating band includes the visible light band, the near-infrared band, or the mid-infrared band.

[0032] A high-speed beam analyzer includes a reflective high-power attenuator, a 1940nm aspherical convex lens with a focal length of 1000mm, an electrically operated polarization-independent folding mirror group 3, an electrically operated optical shutter 4, a 5×3 partitioned two-dimensional virtual image phase array device 5, a large-area CCD, and two residual light collection bins.

[0033] The reflective high-power attenuator can be selected according to the intensity of the input light, with an incident angle of 0°~12° and a reflectivity of 50%~99.9%. The reflected light can be collected by an external light-collecting container.

[0034] The motorized polarization-independent folding mirror group 3 consists of two triangular prisms with a reflectivity of over 99.9% and a motorized displacement platform with a movement accuracy of 0.1 mm, and its maximum displacement length is not less than 100 mm.

[0035] The motorized optical shutter 4 can be a single-blade or multi-blade shutter, or a rotary chopper, and its operating switching frequency is matched with the data acquisition cycle.

[0036] The 5×3 partitioned two-dimensional virtual image phase array device 5 consists of two VIPAs coated with 1940nm wavelength, with a transmittance of 99% and a reflectance of 99.9%; the optical path difference of the first virtual image phase array 5-1 is 50~100mm, which can produce 5 virtual images, such as... Figure 2 As shown; the optical path difference of the second virtual image phase array 5-2 is 10~15mm, which can produce 3 virtual images, such as... Figure 3 As shown; ultimately, it should be ensured that the maximum optical path distribution covers 3 times the Rayleigh length of the focused beam.

[0037] The large-area CCD can detect lasers in the 1940nm band. The internal single pixel size is ≤10um×10um, and the number of pixels in a single dimension is more than 2048. The controller can adjust the light spot intensity of key zones by adjusting the exposure time.

[0038] The residual light collecting barrel absorbs the remaining transmission from the final output surfaces of the first virtual image phase array 5-1 and the second virtual image phase array 5-2, thereby reducing the scattered background light within the system.

[0039] This invention is not limited to the specific embodiments described above; the operating wavelength can be near-infrared, visible light, or other wavelengths. This invention extends to any new features or combinations disclosed in this specification, as well as any new steps or combinations of any new methods or processes disclosed herein.

Claims

1. A high-speed beam quality analyzer, characterized in that, include: The system includes a laser power attenuation device (1), an aberration-free focusing lens (2), a polarization-independent folding mirror group (3), an optical shutter (4), a two-dimensional virtual image phase array device (5), a large-area array camera (6), and a residual light collection barrel; the laser power attenuation device (1) is used to attenuate the power of the beam to be measured, the aberration-free focusing lens (2) is used to converge the beam to be measured, the polarization-independent folding mirror group (3) is used to locate the focal point of the light velocity to be measured, and the optical shutter (4) is used to control the exposure time; After the laser to be tested passes through the two-dimensional virtual image phase array device (5), it forms a virtual image array composed of multiple virtual images arranged in two dimensions. The distance from each virtual image in the virtual image array to the photosensitive surface of the large-area array camera (6) is different, and the distance from each row or column of virtual images in the virtual image array to the photosensitive surface of the large-area array camera (6) is arranged in an approximately arithmetic sequence. The large-area array camera (6) is used to record the light field intensity distribution of the virtual image array. The spot size of each virtual image on the large-area array camera (6) is calculated by the partition image algorithm. Based on the relative difference in distance between each virtual image and the photosensitive surface of the large-area array camera (6), the beam quality of the laser to be tested at the current moment is calculated. The residual light collection bucket includes a first residual light collection bucket (7-1) and a second residual light collection bucket (7-2), which is used to collect residual light that has not entered the large-area array camera (6).

2. The high-speed beam quality analyzer according to claim 1, characterized in that: The two-dimensional virtual image phase array device (5) includes a first virtual image phase array and a second virtual image phase array. The first virtual image phase array and the second virtual image phase array are placed orthogonally. The first virtual image phase array is used to generate a one-dimensional virtual image array in the x direction, and the second virtual image phase array is used to generate a one-dimensional virtual image array in the y direction.

3. The high-speed beam quality analyzer according to claim 2, characterized in that: Both the first virtual image phase array and the second virtual image phase array are a glass plate with two parallel sides coated with a high-reflectivity film, or two parallel single-sided high-reflectivity glass plates.

4. The high-speed beam quality analyzer according to claim 1, characterized in that: The polarization-independent folding mirror group (3) includes a first polarization-independent mirror (3-1), a second polarization-independent mirror (3-2), and a displacement platform (3-3). The displacement platform (3-3) is used to adjust the optical path between the first polarization-independent mirror (3-1) and the second polarization-independent mirror (3-2) so that the focal virtual image of the beam converged by the aberration-free focusing lens (2) is located in the middle region of the photosensitive surface of the large-area array camera (6).

5. The high-speed beam quality analyzer according to claim 4, characterized in that: The displacement platform (3-3) is either an electrically adjustable displacement platform or a mechanical displacement platform.

6. The high-speed beam quality analyzer according to claim 1, characterized in that: In the two-dimensional virtual image phase array device, the center-to-center distance between adjacent virtual images is greater than 3 times the spot diameter of the laser beam to be tested.

7. The high-speed beam quality analyzer according to claim 1, characterized in that: The closing time of the optical shutter (4) is adapted to the refresh cycle and background noise acquisition requirements of the large-area array camera (6). During the closing period of the optical shutter (4), the large-area array camera (6) performs refresh operation and background noise acquisition operation.

8. The high-speed beam quality analyzer according to claim 1, characterized in that: The working band of the large-area array camera (6) covers the wavelength of the laser to be tested, including the visible light band, the near-infrared band, or the mid-infrared band.

Images