Optical transmission calibration method and system for visual laser coaxial calibration based on short wave band pass

Abstract

The invention discloses an optical transmission calibration method and system for visual laser coaxial calibration based on short wave band pass, and the method comprises the following steps: determining a gray scale identification interval of blue light on a camera image plane, and defining the gray scale identification interval as a blue light identification interval; gray level change in a calibration interval is determined through gray level from red light output by a laser to an image surface, focal length parameters are confirmed after gray level from red light saturation to red light unsaturation is confirmed, a red light peak value is found through a zoom curve to serve as a red light calibration basis, and a reference value after a maximum area of a red light response threshold mean value is calibrated is defined as a red light identification interval; carrying out difference recording between the gray values of the red light identification interval and the blue light identification interval, and then judging and outputting the blue light attenuation change; the calibration light source focal length automatic adjustment function and the CMOS parameter automatic adjustment function in laser processing coaxial adjustment measurement are achieved, the equipment adjustment time of technicians is greatly shortened, and the convenience of calibration equipment use is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the field of laser processing technology, and in particular relates to an optical transmission calibration method and system based on short-wave bandpass visual laser coaxial calibration. Background Art

[0002] Laser processing technology is a process for cutting, welding, surface treatment, drilling, and micromachining metal and non-metal materials. It has been widely used in automotive, electronics, electrical appliances, aviation, metallurgy, and machinery manufacturing. However, laser processing requires coaxial laser calibration. Current calibration methods rely on manual work, which is time-consuming, technically demanding, and cumbersome. To address at least one of these technical issues, it is necessary to develop an optical transmission calibration method and system based on shortwave bandpass visual laser coaxial calibration. Summary of the Invention

[0003] The purpose of the present invention is to provide an optical transmission calibration method and system based on short-wave bandpass visual laser coaxial calibration to solve the above technical problems. By calibrating the red light and blue light, automatic exposure adjustment and image plane focal length adjustment of the visual adjustment laser coaxial process are realized, and the functions of automatic adjustment of the focal length of the calibration light source and automatic adjustment of the CMOS parameters in the measurement of laser processing coaxial adjustment are realized, which greatly shortens the equipment adjustment time of technical workers and the convenience of using the calibration equipment.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0005] The optical transmission red light calibration method based on short-wave bandpass visual laser coaxial calibration includes the following steps:

[0006] Determine the grayscale identification interval of blue light on the camera image plane, which is defined as the blue light identification interval;

[0007] The grayscale change within the calibration interval is determined by measuring the grayscale from the laser output red light to the image plane. The focal length parameters are confirmed after the grayscale from the saturation to the non-saturation interval of the red light is confirmed. The red light peak is found through the zoom curve as the basis for calibrating the red light. The reference value after calibrating the maximum area of ​​the red light response threshold mean is defined as the red light identification interval.

[0008] After recording the difference between the grayscale values ​​of the red light identification interval and the blue light identification interval, the blue light attenuation change is determined and output; the CMOS image plane exposure compensation and focus compensation value are performed based on the output result.

[0009] Preferably, the grayscale identification interval of the blue light on the camera image plane is determined by calibrating the grayscale value of the blue light image plane of the device and considering the attenuation problem of blue light use, and performing dark field grayscale calibration on the blue light output beam.

[0010] Preferably, the zoom curve is obtained based on a test of the focal length change of the components of the processing head before and after the red light is focused;

[0011] Based on the characteristic that defocus will cause the peak value of the camera's overall grayscale value to decrease, it is judged whether the camera imaging focus meets the requirements.

[0012] Preferably, the focal length change is adjusted with reference to the red light peak grayscale.

[0013] Preferably, it is characterized in that, according to the relationship between the blue light output power and the overall illumination due to the distance and position, the grayscale value on the camera image plane is a fixed interval, and the interval can be used as an identifier to form a blue light identification interval;

[0014] The grayscale value of the red light after it is projected onto the camera image plane forms the red light identification interval;

[0015] The blue light identification interval is used as a reference to adjust the changes in the red light identification interval of the red light source to adapt to the corresponding camera parameters.

[0016] Preferably, the camera parameters include exposure time, gain, and signal-to-noise ratio.

[0017] Preferably, the overall illumination refers to the line and surface illumination mean formula:

[0018]

[0019] τ is the transmittance of the optical system,

[0020] L is the brightness of the object, the unit is cd / m 2 ,

[0021] D is the entrance pupil diameter of the lens, in mm,

[0022] f' is the focal length of the lens, in mm,

[0023] E' is the radiant illuminance, the unit is mW / mm 2 .

[0024] A system using any of the above-described methods for calibrating red light in optical transmission comprises a nozzle, a window disposed opposite to a light source emitted from the nozzle, a filter disposed on a side of the window away from the nozzle, a lens assembly disposed on a side of the filter away from the window, and a CMOS disposed on a side of the lens assembly away from the filter.

[0025] The light beam emitted by the nozzle passes through the window, filter, and lens group in sequence and then reaches the COMS.

[0026] This application has achieved beneficial technical effects:

[0027] The present invention realizes automatic exposure adjustment and image plane focal length adjustment of the visual adjustment laser coaxial process by calibrating red and blue light, and realizes the function of automatic adjustment of the focal length of the calibration light source and automatic adjustment of CMOS parameters in the measurement of coaxial adjustment of laser processing, which greatly shortens the equipment adjustment time of technical workers and the convenience of using the calibration equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Shown is a schematic diagram of the light source filter calibration scheme;

[0029] Figure 2 Shown is a system schematic.

[0030] Reference numerals

[0031] 1-nozzle; 2-window; 3-filter; 4-lens group; 5-CMOS. DETAILED DESCRIPTION

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific embodiments of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings and other embodiments can be obtained based on these drawings without inventive work.

[0033] The technical solution of the present invention is described in detail below with reference to specific embodiments.

[0034] Reference Figure 1 、 Figure 2 The optical transmission red light calibration method based on short-wave bandpass visual laser coaxial calibration in one embodiment of the present invention comprises the following steps:

[0035] Determine the grayscale identification interval of blue light on the camera image plane, which is defined as the blue light identification interval;

[0036] The grayscale change within the calibration interval is determined by measuring the grayscale from the laser output red light to the image plane. The focal length parameters are confirmed after the grayscale from the saturation to the non-saturation interval of the red light is confirmed. The red light peak is found through the zoom curve as the basis for calibrating the red light. The reference value after calibrating the maximum area of ​​the red light response threshold mean is defined as the red light identification interval.

[0037] After recording the difference between the grayscale values ​​of the red light identification interval and the blue light identification interval, the blue light attenuation change is determined and output; the CMOS image plane exposure compensation and focus compensation value are performed based on the output result.

[0038] In one embodiment, the grayscale identification interval of the blue light on the camera image plane is determined by calibrating the grayscale value of the blue light image plane of the device and considering the attenuation problem of blue light use, and performing dark field grayscale calibration on the blue light output beam.

[0039] In one embodiment, the zoom curve is obtained based on a test of the focal length change of the components of the processing head before and after the red light is focused;

[0040] Based on the characteristic that defocus will cause the peak value of the camera's overall grayscale value to decrease, it is judged whether the camera imaging focus meets the requirements.

[0041] In one embodiment, the focus change is adjusted with reference to the red peak grayscale.

[0042] In one embodiment, based on the relationship between the blue light output power and the overall illumination due to distance and position, the grayscale value on the camera image plane is in a fixed interval, and the interval can be marked to form a blue light marking interval;

[0043] The grayscale value of the red light after it is projected onto the camera image plane forms the red light identification interval;

[0044] The blue light identification interval is used as a reference to adjust the red light identification interval difference to adapt the corresponding camera parameters. Specifically, the value of the identification interval threshold response is used as a reference, that is, the value obtained by superimposing the identification interval and the threshold response;

[0045] In one embodiment, the camera parameters include exposure time, gain, and signal-to-noise ratio.

[0046] In one embodiment, the overall illumination refers to the line and surface illumination mean formula:

[0047]

[0048] τ is the transmittance of the optical system,

[0049] L is the brightness of the object, the unit is cd / m 2 ,

[0050] D is the entrance pupil diameter of the lens, in mm,

[0051] f' is the focal length of the lens, in mm,

[0052] E' is the radiant illuminance, the unit is mW / mm 2 .

[0053] In one embodiment, the calibration scheme may be adjusted for compensation based on the principle of gradient grayscale value changes of a blue light source.

[0054] The present technical solution also provides a system using any of the above-described light transmission red light calibration methods, comprising a nozzle 1, a window 2 arranged in a direction opposite to the light source emitted by the nozzle 1, a filter 3 arranged on a side of the window 2 away from the nozzle 1, a lens group 4 arranged on a side of the filter 3 away from the window 2, and a CMOS 5 arranged on a side of the lens group 4 away from the filter 3;

[0055] The light beam emitted by the nozzle 1 passes through the window 2, filter 3, and lens group 4 in sequence before reaching the COMS 5. The order in which the components of this system are set represents the direction of light transmission. The selection of components must consider the wavelength changes of the light beam after passing through each component and whether it affects the actual red light determination.

[0056] The embodiments of the present invention will be described in detail below with reference to specific examples.

[0057] This technical solution realizes automatic exposure adjustment and image plane focal length adjustment during visual adjustment of laser coaxial process by positioning red light and blue light.

[0058] By calibrating the grayscale value of the blue light image plane of the equipment and considering the attenuation of blue light usage, the blue light output beam is calibrated for dark field grayscale. The grayscale change within the calibration range is determined by outputting red light from the laser to the image plane grayscale. After confirming the grayscale of the saturated to unsaturated interval, the focal length parameters are confirmed. The peak value is found through the zoom curve as the basis for calibrating the red light. After recording the difference between the reference value after calibrating the red light peak and the blue light grayscale value, the blue light attenuation change is determined and output, and the CMOS image plane exposure compensation and focus compensation values ​​are output.

[0059] Due to the relationship between distance and position, the grayscale value of blue light output power (which can be divided into different power levels) and overall illumination on the camera image plane is in a fixed range, which can be marked. For example, if the blue light grayscale is marked in the range of 150-180 (not greater than 255), if the grayscale value of red light is in the range of 100-120 after projection, the blue light reference can be used to adjust the changes in the red light source difference to adapt to the corresponding camera parameters and optimize the image plane results. The specific camera parameters include exposure time, gain, SNR ratio adjustment, etc. to ensure the best imaging effect. Specifically, the quantum response efficiency of red and blue light can be characterized. The quantum response efficiency can refer to the photoelectric response efficiency curves of different CMOS.

[0060] During the red light transmission process, when the red light is searching for focus, the short wavelength of the blue light can suppress the redundant fluctuations of the red light, thereby improving accuracy. The CMOS calibration value corresponding to a wavelength can quickly adjust the basic CMOS response information of the light source that needs to be aligned, reducing the steps of independently adjusting parameters of the device.

[0061] Formula for average line and surface illumination:

[0062]

[0063] τ is the transmittance of the optical system,

[0064] L is the brightness of the object, the unit is cd / m 2 ,

[0065] D is the entrance pupil diameter of the lens, in mm,

[0066] f' is the focal length of the lens, in mm,

[0067] E' is the radiant illuminance, the unit is mW / mm 2 .

[0068] The zoom curve is obtained by testing the focal length change of the components of the processing head before and after red light focusing. Defocusing will cause the overall grayscale value peak of the camera to decrease, which is used to judge whether the camera imaging focus meets the requirements.

[0069] The calibration scheme can refer to the principle of gradient grayscale value change of blue light source for compensation adjustment. Specifically, different red light can be adjusted in combination with the blue light illumination intensity.

[0070] The focal length change is adjusted with reference to the peak grayscale, realizing the zoom adjustment of the processing head and the automatic adjustment of CMOS camera parameters during the coaxial calibration process.

[0071] In this technical solution, if Figure 1 As shown, the blue light is directed outward toward the window 2 to supplement the nozzle. As shown by the dotted line in the figure, the CMOS 5 can detect the reflected light and scattered light of the blue light; the red light is irradiated toward the setting direction of the CMOS 5. Specifically, the red light is irradiated along the setting direction from the window 2 to the CMOS 5.

[0072] In this technical solution, according to the coaxial adjustment requirements of the laser processing beam output calibration, a high-speed adjustment solution for the visual imaging of the beam adjustment lens calibration is provided, and a rapid adjustment solution for the optical parameters of the image plane camera for rapid visual coaxial calibration is provided; the functions of automatic adjustment of the focal length of the calibration light source and automatic adjustment of the CMOS parameters in the measurement of the laser processing coaxial adjustment are realized, which greatly shortens the equipment adjustment time of technical workers and the convenience of using the calibration equipment.

[0073] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

[0075] The above is a detailed description of the embodiments of the optical transmission red light calibration method and system for short-wave bandpass visual laser coaxial calibration provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. An optical transmission calibration method based on short-wave bandpass visual laser coaxial calibration, characterized in that: The steps include: Determine a grayscale identification interval of the first light source on the camera image plane, which is defined as a first identification interval; The grayscale change within the calibration interval is determined by measuring the grayscale of the second light source output by the laser to the image plane. After confirming the grayscale of the saturation to non-saturation interval of the second light source, the focal length parameters are confirmed. The peak value of the second light source is found through the zoom curve as the basis for calibrating the second light source. The reference value after calibrating the maximum area of ​​the mean threshold value of the second light source response is defined as the second identification interval. After recording the difference between the grayscale values ​​of the second identification interval and the first identification interval, the attenuation change of the first light source is determined and output; and CMOS image plane exposure compensation and focus compensation value are performed according to the output result.

2. The optical transmission calibration method based on short-wave bandpass visual laser coaxial calibration according to claim 1 is characterized in that: The first light source is blue light; the second light source is red light; the first identification interval is a blue light identification interval; the second identification interval is a red light identification interval; Determine the grayscale identification interval of blue light on the camera image plane, which is defined as the blue light identification interval; The grayscale change within the calibration interval is determined by measuring the grayscale from the laser output red light to the image plane. The focal length parameters are confirmed after the grayscale from the saturation to the non-saturation interval of the red light is confirmed. The red light peak is found through the zoom curve as the basis for calibrating the red light. The reference value after calibrating the maximum area of ​​the red light response threshold mean is defined as the red light identification interval. After recording the difference between the grayscale values ​​of the red light identification interval and the blue light identification interval, the blue light attenuation change is determined and output; the CMOS image plane exposure compensation and focus compensation value are performed based on the output result.

3. The optical transmission calibration method based on short-wave bandpass visual laser coaxial calibration according to claim 2, characterized in that: The grayscale identification interval of the blue light on the camera image plane is determined by calibrating the grayscale value of the blue light image plane of the device and considering the attenuation problem of blue light use, and performing dark field grayscale calibration on the blue light output beam.

4. The optical transmission calibration method based on short-wave bandpass visual laser coaxial calibration according to claim 2, characterized in that: The zoom curve is obtained based on the focal length change test of the components of the processing head before and after the red light is focused; Based on the characteristic that defocus will cause the peak value of the camera's overall grayscale value to decrease, it is judged whether the camera imaging focus meets the requirements.

5. The optical transmission calibration method based on short-wave bandpass visual laser coaxial calibration according to claim 4 is characterized in that: The focal length change is adjusted with reference to the red light peak grayscale.

6. The optical transmission calibration method based on short-wave bandpass visual laser coaxial calibration according to claim 2, characterized in that: According to the relationship between the blue light output power and the overall illumination due to the distance and position, the grayscale value on the camera image plane is in a fixed range, which can be used as a marker to form a blue light marker range; The grayscale value of the red light after it is projected onto the camera image plane forms the red light identification interval; The blue light identification interval is used as a reference to adjust the changes in the red light identification interval of the red light source to adapt to the corresponding camera parameters.

7. The optical transmission calibration method based on short-wave bandpass visual laser coaxial calibration according to claim 6, characterized in that: The camera parameters include exposure time, gain, and signal-to-noise ratio.

8. The optical transmission calibration method based on short-wave bandpass visual laser coaxial calibration according to claim 6, characterized in that: The overall illumination refers to the line and surface illumination mean formula: τ is the transmittance of the optical system, L is the brightness of the object, the unit is cd / m 2 , D is the entrance pupil diameter of the lens, in mm, f' is the focal length of the lens, in mm, E' is the radiant illuminance, the unit is mW / mm 2 .

9. A system using the optical transmission calibration method according to any one of claims 1 to 8, characterized in that: It comprises a nozzle (1), a window (2) arranged in a direction opposite to the light source emitted by the nozzle (1), a filter (3) arranged on a side of the window (2) away from the nozzle (1), a lens group (4) arranged on a side of the filter (3) away from the window (2), and a CMOS (5) arranged on a side of the lens group (4) away from the filter (3); The light beam emitted by the nozzle (1) passes through the window (2), the filter (3), and the lens group (4) in sequence before reaching the COMS (5).

10. The system of the optical transmission calibration method according to claim 9, characterized in that: The red light is irradiated along the direction from the window piece (2) to the CMOS (5); and the blue light is directed outward toward the window piece (2) to supplement the nozzle (1).

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