A large aperture light spot profile stitching measurement device and method

Abstract

The application relates to a large-aperture light spot appearance splicing measuring device and method, which comprises a beam splitter arranged behind a laser to be measured, used for splitting a large-aperture light beam emitted by the laser to be measured into two paths, i.e. a first light beam and a second light beam, which are respectively used for light beam stability measurement and light spot appearance collection; a light beam stability monitoring module, which comprises a focusing lens, a first shutter, a first attenuating sheet and a first CCD arranged in sequence behind the beam splitter, used for calculating a relative light beam reference position offset by monitoring the stability of the first light beam; and a light spot appearance collection module, which comprises a second attenuating sheet, a second shutter, a second CCD and a two-dimensional motor arranged in sequence behind the beam splitter, used for collecting ROI images of the second light beam based on the offset and splicing the ROI images to obtain a full-aperture light spot appearance. Compared with the prior art, the application solves the problem of poor splicing effect caused by pulse laser beam jitter.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection, and in particular to a measuring device and method for splicing large-aperture light spot morphology. Background Technology

[0002] Beam morphology measurement is crucial in many optical applications, especially in the design, manufacturing, and optimization of high-power lasers and optical systems. Accurate measurement and analysis of beam morphology are essential for ensuring the performance and stability of optical systems, optimizing beam quality, and improving the quality of laser processing and optical communication. In laser processing, the uniformity and stability of the beam morphology directly affect the consistency and precision of the processed surface. In optical transmission and communication, accurate measurement and control of the beam morphology can improve transmission bandwidth, reduce signal distortion, and ensure the stability of communication system performance. In optical manufacturing, measuring the morphology of large-aperture beams allows for feedback and optimization to improve the manufacturing precision of optical components and ensure the performance and quality of optical systems.

[0003] For small-aperture lasers, beam quality analyzers can be used to acquire the beam morphology. However, measuring the morphology of large-aperture lasers requires beam shrinking or stitching. Beam shrinking reduces the beam size and introduces lens aberrations, failing to accurately reflect the true morphology of the beam. Furthermore, due to the jitter of the laser output, especially for pulsed lasers, direct stitching can lead to problems such as misalignment and poor image quality. Summary of the Invention

[0004] The purpose of this invention is to provide a measurement device and method for large-aperture spot morphology stitching that solves the problem of poor stitching effect caused by pulsed laser beam jitter.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A measuring device for large-aperture light spot morphology stitching, comprising:

[0007] Beam splitter: Located after the laser under test, it is used to split the large-aperture beam emitted by the laser under test into two paths, namely the first beam and the second beam, which are used for beam stability measurement and spot morphology acquisition, respectively.

[0008] Beam stability monitoring module: This module includes a focusing lens, a first shutter, a first attenuator, and a first CCD arranged sequentially after the beam splitter. It is used to calculate the offset relative to the beam reference position by monitoring the stability of the first beam.

[0009] Light spot morphology acquisition module: This module includes a second attenuator, a second shutter, a second CCD and a two-dimensional motor arranged sequentially after the beam splitter. It is used to acquire ROI images of the second beam one by one based on the offset and stitch them together to obtain the full aperture light spot morphology.

[0010] Furthermore, the optical path lengths of the first beam and the second beam are the same.

[0011] Furthermore, the beam splitter has a beam splitting ratio of 1:1.

[0012] The present invention also provides a measurement method based on the above-described large-aperture spot morphology stitching measurement device, comprising the following steps:

[0013] Turn on the laser under test, the first shutter, and the second shutter;

[0014] Observe the CCD image and adjust the first and second attenuators to bring the energy to a suitable value.

[0015] The average value of the first beam position is taken as the beam reference position after reading the first beam position several times. The offset relative to the beam reference position is calculated, and the ROI image size and region position of the second beam are set according to the offset.

[0016] The scanning path and step distance of the two-dimensional motor are set, and the two-dimensional motor moves the second CCD to acquire the ROI image of the second beam;

[0017] The two-dimensional motor completes the acquisition, and all the acquired ROI images are stitched together to obtain the full-aperture light spot morphology.

[0018] Furthermore, the two-dimensional motor moves the second CCD to acquire ROI images in a grating scanning manner.

[0019] Furthermore, the size of the raster scan matrix satisfies:

[0020] m×l ROI >d

[0021] n×h POI >d

[0022] In the formula, m×n is the size of the matrix, l ROI ×h ROI d represents the size of the ROI image, and d represents the diameter of the light spot to be measured.

[0023] Furthermore, the stepping distance of the two-dimensional motor is equal to the size of the ROI image.

[0024] Furthermore, the energy is adjusted to a suitable value by increasing or decreasing the number of the first and second attenuators.

[0025] Furthermore, the formula for calculating the size of the ROI image is:

[0026]

[0027]

[0028] l ROI =l-2×Δs xmax

[0029] h ROI =h-2×Δs ymax

[0030] In the formula, Δx max Δy max To obtain the maximum value of the offset relative to the beam reference position among several positions of the first beam read by the first CCD, where f is the focal length of the focusing lens and Δs xmax Δs ymax The maximum offset of the second beam mapped onto the second CCD is given by l0, where l0 is the optical path from the laser output port to the target surface of the second CCD. ROI h ROI The width and height of the ROI image.

[0031] Furthermore, the reading interval when reading the position of the first beam is greater than the pulse interval of the laser under test.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) This invention splits a large-aperture beam into two paths through a beam splitter. One path is used for beam stability measurement, and the other path is used for spot morphology acquisition. In the beam stability measurement, the deviation value between the beam position and the reference position is calculated to determine the size and position of the ROI image based on the deviation value, thereby correcting the ROI image. This allows the full-aperture spot morphology obtained after stitching together all ROI images to effectively improve the influence of laser beam stability on the spot stitching effect.

[0034] (2) In order to prevent the splicing effect from being affected by too weak light intensity or overexposure, the present invention adjusts the first attenuator and the second attenuator to make the laser energy to a suitable value, thereby improving the splicing effect. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the measuring device structure according to an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the grating scanning path according to an embodiment of the present invention;

[0037] Figure 3 The deviation Δx of the first beam relative to the reference position in this embodiment of the invention. i Δyi Schematic diagram;

[0038] Figure 4 The location Δs of the ROI region is set in this embodiment of the invention. xi ,Δs yi ) Schematic diagram;

[0039] Figure 5 This is a schematic diagram of the measurement process according to an embodiment of the present invention;

[0040] Figure 6 This is a schematic diagram illustrating the direct splicing effect of an embodiment of the present invention;

[0041] Figure 7 This is a schematic diagram of the ROI stabilization correction splicing effect in an embodiment of the present invention. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0043] This embodiment provides a measurement device for stitching together the morphology of large-aperture light spots, such as... Figure 1 As shown, the measuring device includes:

[0044] Beam splitter 2: Located after the laser under test 1, it is used to split the large-aperture beam emitted by the laser under test 1 into two paths, namely the first beam and the second beam, which are used for beam stability measurement and spot morphology acquisition, respectively.

[0045] Beam stability monitoring module: This module includes a focusing lens 7, a first shutter 8, a first attenuator 9 and a first CCD (Charge-Coupled Device) 10, which are sequentially arranged after the beam splitter 2. It is used to calculate the offset relative to the beam reference position by monitoring the stability of the first beam.

[0046] Light spot morphology acquisition module: This module includes a second attenuator 3, a second shutter 4, a second CCD 5 and a two-dimensional motor 6, which are sequentially arranged after the beam splitter 2. It is used to acquire the ROI (Region of Interest) images of the second beam one by one based on the offset and stitch them together to obtain the full aperture light spot morphology.

[0047] In this embodiment, the diameter of the beam spot emitted by the laser under test 1 is dmm; the beam splitter 2 has a splitting ratio of 1:1 and a working angle of 45°; the optical path lengths of the first beam and the second beam are equal, i.e., l1 = l2; therefore, the two CCDs acquire the same pulse signal, and the beam offset of the monitoring module and the beam offset of the acquisition module satisfy the following relationship: Where f is the focal length of the focusing lens 7, and Δx i Δy i To monitor the deviation of the beam relative to the reference position in real time, (Δs) xi ,Δs yi The ROI region position of the beam stability monitoring module is set for real-time deviation; l0 is the optical path from the laser output port to the target surface of the second CCD 5; the focusing lens 7 reduces the large-aperture beam to below the target surface size of the first CCD 10, facilitating stability deviation measurement; the first shutter 8 controls the light transmission of the beam stability monitoring module; the first attenuator 9 is used to directly adjust the laser energy of the beam stability monitoring module through the first CCD 10; the first CCD 10 has a target surface size of l×h, as shown in the figure. Figure 3 As shown, the deviation Δx of the beam relative to the reference position is monitored in real time. i Δy i And based on the real-time deviation, the ROI region position of the spot morphology monitoring module is set as (Δs). xi ,Δs yi ),like Figure 4 As shown; the second attenuator 3 is used to adjust the laser energy of the spot morphology acquisition module; the second shutter 4 controls the light transmission of the spot morphology acquisition module; the second CCD 5 has a target surface size of l×h, which is set to l ROI ×h ROI The ROI region is used to collect and stitch the beam pattern; the 2D motor 6 is a 2D stepper motor that controls the movement of the beam analyzer through a 3×4 grating scanning method, with the scanning path as follows: Figure 2 As shown, the ROI scanning area covers the full aperture spot.

[0048] Next, this embodiment performs measurements using the aforementioned measuring device, such as... Figure 5 As shown, the specific measurement steps are as follows:

[0049] Step 1: Turn on the laser under test 1, the first shutter 8, and the second shutter 4.

[0050] The laser under test 1 emits a large-aperture beam, and the first shutter 8 and the second shutter 4 are used to transmit light to the beam stability monitoring module and the spot morphology acquisition module, respectively.

[0051] Step 2: Observe the CCD image and adjust the first attenuator 9 and the second attenuator 3 to bring the energy to a suitable value.

[0052] The large-aperture beam is split into two paths by the beam splitter 2, namely the first beam and the second beam. The first beam is focused by the focusing lens 7, with the focal point located at the center of the CCD target surface, which is used to monitor the stability of the beam in real time. The second beam does not pass through the focusing and is scanned by the CCD controlled by the two-dimensional motor. The acquired images are set according to the real-time stability of the beam, and after the scanning is completed, all ROI images are stitched together to obtain the full-aperture beam shape.

[0053] To prevent insufficient light intensity or overexposure from affecting the stitching effect, the image intensity captured by the CCD at the light intensity peak position should be approximately 80% of the maximum threshold. The laser energy can be adjusted by increasing or decreasing the number of attenuators or by directly adjusting the laser output. In this embodiment, the energy is adjusted to a suitable value by adjusting the number of the first attenuator 9 and the second attenuator 3.

[0054] Step 3: Read the first beam position several times, take the average value as the beam reference position, calculate the offset relative to the beam reference position, and set the size of the ROI image according to the offset.

[0055] Wait 15 minutes for the laser under test to stabilize its output, then collect the reference position of the first beam. Read the centroid data of the beam every t seconds; the reading interval t must be greater than the laser pulse interval. Take n sets of data and calculate their average value. The result is the reference position of the beam. The maximum value of the offset of the n positions relative to the reference position is Δx. max Δy max ,Depend on and l ROI =l-2×Δs xmax h ROI =h-2×Δs ymax Determine the size of ROI ROI ×h ROI , where Δs xmax Δs ymax The maximum value of the offset of the first beam measured n times on the first CCD 10 before splicing is mapped onto the second CCD 5.

[0056] Step 4: Set the scanning path and step distance of the two-dimensional motor 6. The two-dimensional motor 6 moves the second CCD 5 to acquire the ROI image of the second beam.

[0057] 2D motor 6 is a stepper motor. The scanning path and step distance are as follows: Figure 2 As shown, it satisfies 3h ROI >d、4l ROI >d. The stepper motor moves the second CCD 5 to acquire ROI images in a 3×4 raster scan manner, with a step distance equal to the ROI size l. ROI ×h ROIThe scanning range needs to cover all areas of the large-aperture light spot, meaning the size of the grating scanning matrix must satisfy m×l. ROI >d、n×h ROI >d, where d is the diameter of the light spot to be measured.

[0058] like Figure 3 As shown, in this step, the deviation Δx of the beam relative to the reference position is monitored in real time. i Δy i And based on the real-time deviation, the ROI region position of the spot morphology monitoring module is set as (Δs). xi ,Δs yi ),like Figure 4 As shown.

[0059] Step 5: The two-dimensional motor 6 completes the acquisition, and the acquired ROI images are stitched together to obtain the full-aperture light spot morphology.

[0060] The two-dimensional motor 6 collects all ROI images along a predetermined path, stitches them together, and obtains the full-aperture light spot morphology.

[0061] If the images acquired by the second CCD 5 are directly stitched together, the stitched images will not match well because the offset of the light spot acquired at each position relative to the reference position is different. A schematic diagram of the stitching effect is shown below. Figure 6 As shown; the schematic diagram obtained by stitching together after stabilizing the ROI is as follows. Figure 7 As shown, by real-time monitoring of the beam spot stability offset and setting the ROI region, beam stability can be effectively improved.

[0062] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A measuring device for stitching together the morphology of a large-aperture light spot, characterized in that, include: Beam splitter (2): Located after the laser under test (1), it is used to split the large-aperture beam emitted by the laser under test (1) into two paths, namely the first beam and the second beam, which are used for beam stability measurement and spot morphology acquisition, respectively. The optical path of the first beam and the optical path of the second beam are the same. Beam stability monitoring module: This module includes a focusing lens (7), a first shutter (8), a first attenuator (9) and a first CCD (10) arranged sequentially after the beam splitter (2), for calculating the offset relative to the beam reference position by monitoring the stability of the first beam, wherein the focusing lens (7) reduces the first beam to below the target surface size of the first CCD (10); The light spot morphology acquisition module includes a second attenuator (3), a second shutter (4), a second CCD (5) and a two-dimensional motor (6) arranged sequentially after the beam splitter (2). It is used to set the ROI region position of the second beam based on the offset, acquire the ROI image of the second beam one by one and stitch them together to obtain the full aperture light spot morphology. The two-dimensional motor (6) controls the second CCD (5) to perform light spot scanning.

2. The measuring device for large-aperture light spot morphology stitching according to claim 1, characterized in that, The beam splitter (2) has a beam splitting ratio of 1:

1.

3. A measurement method based on the large-aperture spot morphology stitching measurement device according to any one of claims 1-2, characterized in that, Includes the following steps: Turn on the laser under test (1), the first shutter (8), and the second shutter (4); Observe the CCD image and adjust the first attenuator (9) and the second attenuator (3) to bring the energy to a suitable value; The average value of the first beam position is taken as the beam reference position after reading the first beam position several times. The offset relative to the beam reference position is calculated, and the ROI image size and region position of the second beam are set according to the offset. Set the scanning path and step distance of the two-dimensional motor (6), and the two-dimensional motor (6) moves the second CCD (5) to acquire the ROI image of the second beam; The two-dimensional motor (6) completes the acquisition and stitches together all the acquired ROI images to obtain the full aperture spot morphology.

4. The measurement method according to claim 3, characterized in that, The two-dimensional motor (6) moves the second CCD (5) in a grating scanning manner to acquire ROI images.

5. The measurement method according to claim 4, characterized in that, The size of the raster scan matrix satisfies: In the formula, m n Size of the matrix The size of the ROI image. d The diameter of the light spot to be measured is denoted as .

6. The measurement method according to claim 3, characterized in that, The stepping distance of the two-dimensional motor (6) is the size of the ROI image.

7. The measurement method according to claim 3, characterized in that, The energy is adjusted to a suitable value by increasing or decreasing the number of the first attenuator (9) and the second attenuator (3).

8. The measurement method according to claim 3, characterized in that, The formula for calculating the size of the ROI image is: In the formula, , To read the maximum value of the offset relative to the beam reference position among several positions of the first beam by the first CCD (10), f The focal length of the focusing lens (7) is... , The maximum value of the offset mapped to the second beam on the second CCD (5) The optical path from the laser output port to the target surface of the second CCD (5) is given. , The width and height of the ROI image.

9. The measurement method according to claim 3, characterized in that, The reading interval when reading the position of the first beam is greater than the pulse interval of the laser under test (1).

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