Defect probability trigger detection system based on process database

Abstract

The present application relates to the field of optical technology, especially to a defect probability trigger detection system based on a process database, comprising a blue light scanning system for detecting a workpiece to be detected, wherein the blue light scanning system comprises an industrial computer, and the industrial computer stores a process database; the process database has a defect parameter library, and the defect categories are probabilistically associated. By setting the probabilistically associated defect parameter library, an intelligent trigger mechanism is established, and the review of other possible defects determined by probability association by the laser scanning system is automatically triggered, thereby saving detection time, reducing the risk of missing small associated defects, and achieving a balance between detection efficiency and reliability.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and in particular to a defect probability-triggered detection system based on a process database. Background Technology

[0002] An aero engine is a highly complex and precise thermodynamic machine, comprising five core components: intake system, compressor, combustion chamber, turbine, and exhaust system. These components work together to form the engine's gas passage and core mechanical system.

[0003] Among them, the compressor and turbine, as high-speed rotating components, are composed of a large number of blades, disks, shafts, etc. After these precision parts are manufactured, their geometric dimensions and form and position tolerances must strictly comply with the design specifications. Any manufacturing defects, such as distortion and deformation caused by improper heat treatment, inclusions generated during the casting process, or surface damage caused by the demolding process, may become potential safety hazards. Under extreme operating conditions (high temperature, high pressure, high speed), they may cause serious engine failures. Therefore, these precision parts must be subjected to comprehensive and precise defect detection before assembly.

[0004] Currently, defect detection mainly relies on coordinate measuring machines (CMMs) and blue light scanners. While CMMs offer high precision through contact-based single-point measurement, they are time-consuming and inefficient, making them unsuitable for full inspection in mass production. Blue light scanners, on the other hand, are non-contact optical measurement devices that can identify whether the surface geometric parameters of precision parts are out of tolerance. Their measurement accuracy is typically at the micrometer level. However, when a certain area has a significant defect, related areas with mechanical transmission or structural continuity relationships often experience nanometer-level micro-deformations. These tiny associated defects are difficult for blue light scanners to effectively capture, affecting the fatigue life and reliability of precision parts. Summary of the Invention

[0005] The purpose of this invention is to provide a defect probability-triggered detection system based on a process database to solve at least one of the above-mentioned technical problems.

[0006] The technical problem solved by the invention can be achieved using the following technical solutions:

[0007] The defect probability-triggered detection system based on the process database includes a blue light scanning system for detecting the workpiece to be inspected. The blue light scanning system includes an industrial control computer, which stores the process database.

[0008] The process database contains a defect parameter library, and defect categories are probabilistically associated. The association method for defect categories is as follows:

[0009] Based on statistics, if the probability of another defect existing when one defect occurs is greater than 30%, then the two are probabilistically correlated.

[0010] When a defect is detected, the detection of other defects is triggered through probability correlation;

[0011] The industrial computer is also connected to a laser scanning system;

[0012] The laser scanning system includes a beam splitter that separates a measurement beam and a reference beam with an angle between 5 and 15 degrees.

[0013] The measuring beam and the reference beam are projected onto the surface of the workpiece to be inspected, and are reflected by the surface of the workpiece to be inspected, forming two reflected beams;

[0014] The laser scanning system also includes two light-shielding channels that are parallel to the pointing directions of the measurement beam and the reference beam, respectively;

[0015] Optical components are installed behind the two light-shielding channels to adjust the two reflected rays and make them interfere.

[0016] First, a blue light scanning system is used to perform an overall scan. After detecting a defect, the laser scanning system is activated to perform a more precise spot scan on other possible defects determined by probability correlation.

[0017] An optical path adjuster is provided in the optical path of the measuring beam. The optical path adjuster includes a copper tube, and both ends of the copper tube are sealed by a flat and transparent glass plate. The end face of the glass plate is perpendicular to the optical path direction of the measuring beam.

[0018] It is also equipped with a liquid nitrogen evaporation refrigeration system, with the refrigeration pipes of the liquid nitrogen evaporation refrigeration system wrapped around copper pipes.

[0019] In the above design, an intelligent triggering mechanism is established by setting up a defect parameter library based on probability correlation. This mechanism enables the blue light scanning system and the laser scanning system to work together. After the blue light scanning system detects a defect, it automatically triggers the laser scanning system to re-examine other possible defects identified by probability correlation. This saves detection time and reduces the risk of missing minor associated defects, achieving a balance between detection efficiency and reliability.

[0020] The defect parameter library contains the design model data of the workpiece to be inspected, the location coordinates of at least one high-risk area, and the location coordinates of at least one associated hazardous area. The high-risk area is the area of ​​the workpiece to be inspected that is prone to deformation or surface damage during the manufacturing process. The associated hazardous area is the area that has a mechanical transmission or structural continuity relationship with the high-risk area. Statistically, it has been found that when an anomaly occurs in the high-risk area, the probability of associated deformation or damage is greater than 30%. When the blue light scanning system detects a defect within the coordinate range of a certain high-risk area, it can determine that the associated hazardous area with a mechanical transmission or structural continuity relationship with that location has an extremely high risk of associated damage. This enables the laser scanner to perform more precise flaw detection on the defect location and associated hazardous areas, avoiding the redundant operation of the coordinate measuring machine and the risk of missed detection by the blue light scanner, and improving the reliability and accuracy of the detection results.

[0021] Traditional laser scanning systems are high-precision measuring instruments based on the principle of interference. During the scanning process, it is unavoidable that there will be relative displacement and relative angle changes between the laser and the surface of the workpiece to be inspected, at least at the micrometer level. This causes irregular jumps in the interference fringes, making it impossible to scan out the real defect area.

[0022] This patent application eliminates the fixed reference mirror in traditional laser scanning systems, using the surface of the workpiece to be inspected as the reflecting surface of both the measuring beam and the reference beam. Since the two beams scan synchronously, any common displacement or angular change between the laser scanning system and the workpiece to be inspected has a synchronous and equal effect on the optical path of both beams. Therefore, the optical path difference between the measuring beam and the reference beam changes synchronously and is almost unaffected by slight positional changes between the laser scanning system and the surface of the workpiece to be inspected. This avoids the problem of irregular jumps in interference imaging during the scanning process, making it easier to accurately scan the location of minute damage. Theoretically, the scanning accuracy can be at the level of several micrometers or even nanometers.

[0023] Both the reference beam and the measurement beam are reflected from the surface of the workpiece to be tested, forming two reflected beams. After the direction is adjusted by the light-shielding channel and optical components, they finally form interference. The two beams serve as a reference to each other and are compared and verified by the surface of the workpiece to be tested at different positions. This constitutes a self-reference interferometric measurement system, which can accurately and reliably identify interference fringe anomalies caused by minute defects, so as to intuitively and quickly discover damage on the surface of the workpiece to be tested.

[0024] By setting up a light-shielding channel, only reflected light rays that are nearly parallel to the direction of the light-shielding channel can pass through, while light rays with a large angle difference are blocked by the light-shielding channel.

[0025] By setting up two optical components, the reflected light rays passing through the light-blocking channel are converted into parallel light, so that the two reflected light rays can eventually form a stable and clear interference pattern.

[0026] Secondly, this patent application also introduces a liquid nitrogen evaporative cooling system. The liquid nitrogen evaporative cooling system achieves precise control of the gas refractive index by cooling. Based on the ideal gas law PV=nRT, in a closed pipeline, the volume V and the amount of gas n remain constant. Therefore, the pressure P is directly proportional to the temperature T. By actively cooling the pipeline through the liquid nitrogen evaporative cooling system, according to the above formula, the decrease in temperature T will directly lead to a synchronous decrease in gas pressure P. The gas molecules are more densely distributed in a fixed space, that is, the gas density increases significantly. Since the refractive index of the gas is directly proportional to the gas density, precise control of the gas refractive index is achieved.

[0027] Preferably, it also includes an air compressor, the air outlet of which is connected to the interior of the optical path regulator, and the air inlet of which is connected to a gas container storing sulfur hexafluoride gas.

[0028] Preferably, a temperature sensor is attached to the inner wall of the copper tube. The temperature sensor is connected to the temperature signal input terminal of the control system of the liquid nitrogen evaporation refrigeration system, enabling feedback control of the temperature inside the copper tube. Based on the temperature sensor feedback control, the liquid nitrogen evaporation refrigeration system can monitor and dynamically adjust the temperature within the optical path regulator in real time, achieving precise control of the gas refractive index.

[0029] Preferably, the light-shielding channel has a straight circular tube inner wall, and the length of the light-shielding channel is 5cm to 15cm and the diameter is 0.3cm to 1cm.

[0030] Preferably, the inner wall of the straight circular tube of the light-shielding channel is provided with at least one continuous spiral baffle, and the extension length of the spiral baffle towards the center is 0.05cm to 0.1cm; and both the inner wall of the straight circular tube and the surface of the spiral baffle are coated with a light-absorbing coating of black copper. By providing a spiral baffle on the inner wall of the straight circular tube of the light-shielding channel and coating its surface with a light-absorbing coating of black copper, light rays with a large angle difference from the light-shielding channel are struck by the inclined side of the spiral baffle and absorbed, while reflected light rays parallel to the direction of the light-shielding channel can pass smoothly.

[0031] Preferably, the laser scanning system further includes a reflector, a converging lens, and a grating. The reflector is located behind the light-shielding channel. The reflected light rays passing through the light-shielding channel are reflected by the reflector to form a beam. The converging lens is located on the optical path of this beam, and the beam passing through the converging lens is projected onto the grating. By setting reflectors behind the two light-shielding channels respectively, the reflected light rays passing through the two light-shielding channels are reflected by their corresponding reflectors to form two parallel reflected light beams, so as to ultimately form a stable, clear, and high-contrast interference image.

[0032] Preferably, the laser scanning system is mounted on a pan-tilt unit, and a vertically lifting hydraulic lifting device is installed below the pan-tilt unit. The workpiece to be inspected is placed vertically, with the part of the workpiece to be inspected facing the laser scanning system. The laser scanning system rotates horizontally and moves vertically, causing the reference beam and the measuring beam to move synchronously, scanning the deviation area and associated danger area.

[0033] Preferably, the following process is adopted during use:

[0034] Step S1: Clamping and positioning of the workpiece to be inspected: Place the workpiece to be inspected vertically;

[0035] Step S2: Overall morphology scanning of the workpiece to be inspected: Start the blue light scanning system to perform an overall scan of the workpiece to be inspected and obtain the three-dimensional morphology data of the surface of the workpiece to be inspected.

[0036] Step S3: Identify defect points: Compare the three-dimensional topography data obtained in step S2 with the design model data in the process database, mark the deviation as defect points, and record them as a defect.

[0037] Step S4: Laser scanning system calibration: Start the laser scanning system and focus the measurement beam and reference beam on the smooth and intact surface next to the defect point. Adjust the pressure and density of sulfur hexafluoride gas in the optical path adjuster by using an air compressor, and adjust the temperature of sulfur hexafluoride gas by using a liquid nitrogen evaporation cooling system. Precisely adjust the optical path difference until a clear and stable interference image is obtained, and set this image as the standard interference image.

[0038] Step S5: Accurately confirm the defect point: The laser scanning system scans the defect point and acquires multiple sets of measurement interference images. Each set of measurement interference images is compared with the standard interference image obtained in step S4. When a change in the interference image that exceeds the set threshold is detected, the point is confirmed as a defect point.

[0039] Step S6: Defect extension detection: Based on the preset defect probability association rules, the laser scanning system moves to other defect locations that are probabilistically associated with the currently confirmed defect point, and repeats steps S5 to S6 to perform fixed-point scanning and confirmation.

[0040] In summary, the present invention has the following beneficial effects:

[0041] 1. By setting up a defect parameter library based on probability correlation, an intelligent triggering mechanism was established, enabling the blue light scanning system and the laser scanning system to work together. After the blue light scanning system detects a defect, it automatically triggers the laser scanning system to re-examine other possible defects identified by probability correlation. This saves detection time and reduces the risk of missing minor associated defects, achieving a balance between detection efficiency and reliability.

[0042] 2. This patent application eliminates the fixed reference mirror in traditional laser scanning systems, and uses the surface of the workpiece to be inspected as the reflecting surface of both the measuring beam and the reference beam. Since the two beams scan synchronously, any common displacement or angular change between the laser scanning system and the workpiece to be inspected has a synchronous and equal effect on the two optical paths. Therefore, the optical path difference between the measuring beam and the reference beam changes synchronously and is almost unaffected by slight changes in the position between the laser scanning system and the surface of the workpiece to be inspected. This avoids the problem of irregular jumps in interference imaging during the scanning process, so as to accurately scan the location of tiny damage. Theoretically, the scanning accuracy can be at the level of several micrometers or even nanometers.

[0043] 3. An optical path adjuster is set in the optical path of the measuring beam, and the pressure and density of sulfur hexafluoride gas in the optical path adjuster are adjusted by an air compressor. The temperature of sulfur hexafluoride gas is adjusted by a liquid nitrogen evaporation refrigeration system, and the optical path difference is precisely adjusted to achieve precise control of the gas refractive index. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the overall structure of the defect probability-triggered detection system based on a process database according to the present invention.

[0045] Figure 2 The present invention relates to a defect probability-triggered detection system based on a process database. Figure 1 Enlarged structural diagram at point A;

[0046] Figure 3 This is a cross-sectional structural diagram of a copper tube in the defect probability triggering detection system based on a process database according to the present invention.

[0047] Figure 4 This is a schematic diagram illustrating the structure of the reflector in the defect probability triggering detection system based on the process database of the present invention.

[0048] Figure 5 This is a flowchart of the defect probability triggering detection system based on a process database according to the present invention.

[0049] In the diagram, 1. Blue light scanning system; 2. Laser scanning system; 3. Light-shielding channel; 4. Copper pipe; 5. Glass plate; 6. Cooling pipe; 8. Reflector; 9. Converging lens; 10. Gimbal; 11. Hydraulic lifting device. Detailed Implementation

[0050] To make the technical means, creative features, objectives and effects of the invention easier to understand, the invention will be further explained below with reference to specific illustrations.

[0051] refer to Figures 1 to 5The system includes a blue light scanning system 1 for inspecting the workpiece to be inspected. The blue light scanning system 1 includes an industrial control computer, which stores a process database.

[0052] The process database contains a defect parameter library, and defect categories are probabilistically associated. The association method for defect categories is as follows:

[0053] Based on statistical findings, if the probability of another defect existing when one defect occurs is greater than 30%, then the two defects are probabilistically correlated.

[0054] When a defect is detected, the detection of other defects is triggered through probability correlation;

[0055] The industrial computer is also connected to a laser scanning system 2;

[0056] The laser scanning system 2 includes a beam splitter that splits a measurement beam and a reference beam with an angle between 5 and 15 degrees.

[0057] The measuring beam and the reference beam are projected onto the surface of the workpiece to be inspected, and are reflected by the surface of the workpiece to be inspected, forming two reflected beams;

[0058] The laser scanning system 2 also includes two light-shielding channels 3 that are parallel to the pointing directions of the measurement beam and the reference beam, respectively;

[0059] Optical components are respectively installed behind the two light-shielding channels 3 to adjust the two reflected rays and make them interfere;

[0060] First, a full scan is performed using the blue light scanning system 1. After detecting a defect, the laser scanning system 2 is activated to perform a more precise spot scan on other possible defects determined by probability correlation.

[0061] An optical path adjuster is provided in the optical path of the measuring beam. The optical path adjuster includes a copper tube 4. Both ends of the copper tube 4 are sealed by a flat and transparent glass plate 5. The end face of the glass plate 5 is perpendicular to the optical path direction of the measuring beam.

[0062] It is also equipped with a liquid nitrogen evaporation refrigeration system, with the refrigeration pipe 6 of the liquid nitrogen evaporation refrigeration system wrapped around the copper pipe 4.

[0063] The above design establishes an intelligent triggering mechanism by setting up a defect parameter library with probabilistic correlation, enabling the blue light scanning system 1 and the laser scanning system 2 to work together. After the blue light scanning system 1 detects a defect in the overall scan, it automatically triggers the laser scanning system 2 to re-examine other possible defects determined by probabilistic correlation. This saves detection time and reduces the risk of missing minor associated defects, achieving a balance between detection efficiency and reliability.

[0064] The defect parameter library contains the design model data of the workpiece to be inspected, the location coordinates of at least one high-risk area, and the location coordinates of at least one associated hazardous area. The high-risk area is the area of ​​the workpiece to be inspected that is prone to deformation or surface damage during the manufacturing process. The associated hazardous area is the area that has a mechanical transmission or structural continuity relationship with the high-risk area. Statistically, it has been found that when an anomaly occurs in the high-risk area, the probability of associated deformation or damage is greater than 30%. When the blue light scanning system 1 detects a defect within the coordinate range of a certain high-risk area, it can determine that the associated hazardous area with a mechanical transmission or structural continuity relationship with that location has an extremely high risk of associated damage. This enables the laser scanner to perform more precise flaw detection on the defect location and associated hazardous areas, avoiding the redundant operation of the coordinate measuring machine and the risk of missed detection by the blue light scanner, and improving the reliability and accuracy of the detection results.

[0065] Traditional laser scanning systems are high-precision measuring instruments based on the principle of interference. During the scanning process, it is unavoidable that there will be relative displacement and relative angle changes between the system and the surface of the workpiece to be inspected, at least at the micrometer level. This causes irregular jumps in the interference fringes, making it impossible to scan the true defect area.

[0066] This patent application eliminates the fixed reference mirror in the traditional laser scanning system 2, and uses the surface of the workpiece to be inspected as the reflecting surface of both the measuring beam and the reference beam. Since the two beams scan synchronously, any common displacement or angular change between the laser scanning system 2 and the workpiece to be inspected has a synchronous and equal effect on the optical path of the two beams. Therefore, the optical path difference between the measuring beam and the reference beam changes synchronously and is almost unaffected by slight changes in the position between the laser scanning system 2 and the surface of the workpiece to be inspected. This avoids the problem of irregular jumps in interference imaging during the scanning process, so as to accurately scan the location of tiny damage. Theoretically, the scanning accuracy can be at the level of several micrometers or even nanometers.

[0067] Both the reference beam and the measurement beam are reflected from the surface of the workpiece to be tested, forming two reflected beams. After the direction is adjusted by the light-shielding channel 3 and the optical components, they finally form interference. The two beams serve as a reference to each other and are compared and verified by the surface of the workpiece to be tested at different positions. This constitutes a self-reference interferometric measurement system, which can accurately and reliably identify interference fringe anomalies caused by minute defects, so as to intuitively and quickly discover damage to the surface of the workpiece to be tested.

[0068] By setting up the light-shielding channel 3, only reflected light rays that are nearly parallel to the direction of the light-shielding channel 3 can pass through, while light rays with a large angle difference are blocked by the light-shielding channel 3.

[0069] By setting two optical components, the reflected light rays passing through the light-shielding channel 3 are converted into parallel light, so that the two reflected light rays can eventually form a stable and clear interference pattern.

[0070] Secondly, this patent application also introduces a liquid nitrogen evaporative cooling system. The liquid nitrogen evaporative cooling system achieves precise control of the gas refractive index by cooling. Based on the ideal gas law PV=nRT, in a closed pipeline, the volume V and the amount of gas n remain constant. Therefore, the pressure P is directly proportional to the temperature T. By actively cooling the pipeline through the liquid nitrogen evaporative cooling system, according to the above formula, the decrease in temperature T will directly lead to a synchronous decrease in gas pressure P. The gas molecules are more densely distributed in a fixed space, that is, the gas density increases significantly. Since the refractive index of the gas is directly proportional to the gas density, and the control precision of the liquid nitrogen evaporative cooling system is much greater than that of the control precision of relying on an air compressor, the fluctuation of the refractive index is controlled within a very small range, thus achieving precise regulation of the gas refractive index.

[0071] It also includes an air compressor, the air compressor's outlet is connected to the interior of the optical path regulator, and the air compressor's inlet is connected to a gas container that stores sulfur hexafluoride gas. Sulfur hexafluoride gas with a high refractive index is selected. The pressure and density of the sulfur hexafluoride gas in the optical path regulator are adjusted by the air compressor to adjust the optical path difference.

[0072] A temperature sensor is attached to the inner wall of copper tube 4. The temperature sensor is connected to the temperature signal input terminal of the control system of the liquid nitrogen evaporative cooling system, realizing feedback control of the temperature inside copper tube 4. Based on the temperature sensor feedback control, the liquid nitrogen evaporative cooling system can monitor and dynamically adjust the temperature inside the optical path regulator in real time, achieving precise control of the gas refractive index.

[0073] The light-shielding channel 3 adopts a straight circular tube inner wall, and the length of the light-shielding channel 3 is 5cm~15cm and the diameter is 0.3cm~1cm.

[0074] The inner wall of the straight circular tube of the light-shielding channel 3 is provided with at least one continuous spiral baffle, and the extension length of the spiral baffle towards the center is 0.05cm to 0.1cm; both the inner wall of the straight circular tube and the surface of the spiral baffle are coated with a light-absorbing coating of black copper. By setting the spiral baffle on the inner wall of the straight circular tube of the light-shielding channel 3 and coating its surface with a light-absorbing coating of black copper, light rays with a large angle difference from the light-shielding channel 3 are struck by the inclined side of the spiral baffle and absorbed, while reflected light rays parallel to the pointing direction of the light-shielding channel 3 can pass through smoothly.

[0075] The laser scanning system 2 also includes a reflector 8, a converging lens 9, and a grating. The reflector 8 is located behind the light-shielding channel 3. The reflected light rays passing through the light-shielding channel 3 are reflected by the reflector 8 to form a beam. The converging lens 9 is located on the optical path of this beam, and the beam passing through the converging lens 9 is projected onto the grating. By setting reflectors 8 behind the two light-shielding channels 3 respectively, the reflected light rays passing through the two light-shielding channels 3 are reflected by the corresponding reflectors 8 to form two parallel reflected light rays, so as to ultimately form a stable, clear, and high-contrast interference image.

[0076] The laser scanning system 2 is mounted on a pan-tilt unit 10, and a vertically lifting hydraulic lifting device 11 is installed below the pan-tilt unit 10. The workpiece to be inspected is placed vertically, with the part of the workpiece to be inspected facing the laser scanning system 2. The laser scanning system 2 rotates horizontally and moves vertically, so that the reference beam and the measuring beam move synchronously to scan the deviation area and the associated danger area.

[0077] The following process is adopted when using it:

[0078] Step S1: Clamping and positioning of the workpiece to be inspected: Place the workpiece to be inspected vertically;

[0079] Step S2: Overall morphology scanning of the workpiece to be inspected: Start the blue light scanning system 1 to perform an overall scan of the workpiece to be inspected and obtain the three-dimensional morphology data of the surface of the workpiece to be inspected.

[0080] Step S3: Identify defect points: Compare the three-dimensional topography data obtained in step S2 with the design model data in the process database, mark the deviation as defect points, and record them as a defect.

[0081] Step S4: Calibrate the laser scanning system 2: Start the laser scanning system 2, focus the measurement beam and the reference beam on the smooth and intact surface next to the defect point, adjust the pressure and density of sulfur hexafluoride gas in the optical path adjuster by the air compressor, adjust the temperature of sulfur hexafluoride gas by the liquid nitrogen evaporation cooling system, and precisely adjust the optical path difference until a clear and stable interference image is obtained, and set this image as the standard interference image.

[0082] Step S5: Accurately confirm the defect point: The laser scanning system 2 scans the defect point and acquires multiple sets of measurement interference images. Each set of measurement interference images is compared with the standard interference image obtained in step S4. When a change in the interference image exceeding the set threshold is detected, the point is confirmed as a defect point.

[0083] Step S6: Defect extension detection: Based on the preset defect probability association rules, the laser scanning system 2 moves to other defect locations that are probabilistically associated with the currently confirmed defect point, and repeats steps S5 to S6 to perform fixed-point scanning and confirmation.

[0084] When in use, the operator first fixes the workpiece to be inspected on a detection platform, adjusts the workpiece to be inspected to a vertical position, and makes the surface of the workpiece to be inspected face the laser scanning system 2.

[0085] First, the blue light scanning system 1 is started, and blue light stripes are projected onto the surface of the workpiece to be inspected for a rapid overall scan to obtain the three-dimensional morphological data of the surface of the workpiece. The industrial control computer compares the obtained three-dimensional morphological data with the design model data in the process database and initially marks the areas with deviations as defect points.

[0086] Then, the laser scanning system 2 is activated. The measuring beam and the reference beam are precisely focused on the smooth and intact surface next to the defect point. The smooth and intact surface next to the defect point is located within 3 mm of the edge of the defect point and is scanned and detected by the blue light scanning system 1. It is determined that the deviation between its three-dimensional morphology data and the design data is within the allowable tolerance of the surface area of ​​the workpiece to be inspected. The pressure and density of sulfur hexafluoride gas in the optical path adjuster are adjusted by the air compressor, and the temperature of sulfur hexafluoride gas is adjusted by the liquid nitrogen evaporation cooling system. The optical path of the measuring beam is actively changed until a clear and stable standard interference image is obtained on the interferometer. This image serves as the defect-free benchmark for subsequent comparison.

[0087] The laser scanning system 2 rotates slowly and smoothly horizontally, causing the reference beam and the measurement beam to move synchronously. It scans the defect points on the surface of the workpiece to be inspected and acquires multiple measurement interference images. The industrial control computer compares these measurement interference images with the standard interference image. When the industrial control computer detects a change that exceeds the preset threshold, it confirms the location as a defect point.

[0088] After a defect is identified, the laser scanning system 2 moves to another possible defect location that is associated with the probability of the current defect point for detection scanning, according to the defect probability association rule. For qualified areas, no significant change in optical path difference occurs during the scanning process of the measurement beam and the reference beam. When the change in optical path difference shown in the interference image is greater than the set amplitude, it is considered that a defect point has been detected.

[0089] The foregoing has shown and described the basic principles, main features, and advantages of the invention. Those skilled in the art should understand that the invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made without departing from the spirit and scope of the invention, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection of the invention is defined by the appended claims and their equivalents.

Claims

1. Defect probability trigger detection system based on process database, comprising a blue light scanning system (1) for detecting a workpiece to be detected, the blue light scanning system (1) comprising an industrial computer, characterized in that: The industrial computer stores a process database; The process database has a defect parameter library, and the defect categories are probabilistically associated, and the association mode of the defect categories is: Based on statistics, when one defect occurs, the probability of another defect existing is greater than 30%, then the two are probabilistically associated; When a defect is detected, the detection of other defects associated by probability is triggered; The industrial computer is also connected with a laser scanning system (2); The laser scanning system (2) includes a beam splitter, which divides the measurement beam and the reference beam with an included angle of 5-15 degrees; The measurement beam and the reference beam are projected onto the surface of the workpiece to be detected and are reflected by the surface of the workpiece to be detected respectively, forming two reflected light beams; The laser scanning system (2) further includes two light shielding channels (3) parallel to the pointing directions of the measurement beam and the reference beam respectively; The rear of the two light shielding channels (3) is respectively provided with an optical assembly to adjust the two reflected light beams and make them interfere; First, the whole scanning is carried out by the blue light scanning system (1), after detecting a defect, the laser scanning system (2) is started, and more accurate point scanning is carried out on other possible defects determined by probability association; An optical path adjuster is arranged on the optical path of the measurement beam, the optical path adjuster includes a copper pipe (4), the two ends of the copper pipe (4) are sealed by flat and transparent glass plates (5), and the end faces of the glass plates (5) are perpendicular to the optical path direction of the measurement beam; A liquid nitrogen evaporation refrigeration system is also provided, and a refrigeration pipe (6) of the liquid nitrogen evaporation refrigeration system is wrapped outside the copper pipe (4); Further comprising an air compressor, the air outlet of the air compressor is communicated with the inside of the optical path adjuster, the air inlet of the air compressor is connected with a gas container, the gas container stores sulfur hexafluoride gas, and the pressure and density of the sulfur hexafluoride gas in the optical path adjuster are adjusted by the air compressor; The temperature of the sulfur hexafluoride gas is adjusted by the liquid nitrogen evaporation refrigeration system, the optical path difference is precisely adjusted, and a clear and stable interference image is obtained, which is set as a standard interference image.

2. The process database based defect probability triggered detection system of claim 1, wherein: The liquid nitrogen evaporation refrigeration system realizes precise control of the refractive index of the gas by cooling, based on the ideal gas state equation PV=nRT, in a closed pipeline, the volume V and the amount of substance n of the gas remain unchanged, so the pressure P and the temperature T are in a proportional relationship, the pipeline is actively cooled by the liquid nitrogen evaporation refrigeration system, according to the above formula, the decrease of the temperature T will directly lead to the synchronous decrease of the gas pressure P, the gas molecules are distributed more closely in the fixed space, that is, the gas density increases significantly, and the refractive index of the gas is proportional to the gas density, so the refractive index of the gas is precisely controlled.

3. The process database based defect probability triggered detection system of claim 1, wherein: A temperature sensor is attached to the inner wall of the copper pipe (4), the temperature sensor is connected with the temperature signal input end of the control system of the liquid nitrogen evaporation refrigeration system, and the feedback control of the temperature in the copper pipe (4) is realized.

4. The process database based defect probability triggered detection system of claim 1, wherein: The light shielding channel (3) adopts a straight circular tube type inner wall, the length of the light shielding channel (3) is 5-15 cm, and the caliber is 0.3-1 cm.

5. The process database based defect probability triggered detection system of claim 1, wherein: The straight circular tube type inner wall of the light shielding channel (3) is provided with at least one continuous spiral-shaped baffle, and the extension length of the spiral-shaped baffle to the middle part is 0.05-0.1 cm. And the inner wall of straight circular tube type and the surface of helical baffle are coated with black copper light-absorbing coating.

6. The process database based defect probability triggered detection system of claim 1, wherein: The laser scanning system (2) further comprises a mirror (8), a converging lens (9) and a grating; The mirror (8) is located behind the light shielding channel (3), the reflected light passing through the light shielding channel (3) is reflected by the mirror (8) to form a light beam, the converging lens (9) is located on the light path of the light beam, and the light beam passing through the converging lens (9) is projected to the grating.

7. The process database based defect probability triggered detection system of claim 1, wherein: The laser scanning system (2) is arranged on a holder (10), and a vertical lifting hydraulic lifting device (11) is arranged below the holder (10).

8. The process database based defect probability triggered detection system of claim 1, wherein: In use, the following process is adopted: Step S1: clamping and positioning of the workpiece to be detected: the workpiece to be detected is placed vertically; Step S2: overall appearance scanning of the workpiece to be detected: the blue light scanning system (1) is started to scan the workpiece to be detected as a whole, and three-dimensional appearance data of the surface of the workpiece to be detected is obtained; Step S3: identifying defect points: comparing the three-dimensional appearance data obtained in step S2 with the design model data in the process database, the deviation part is marked as a defect point, and is recorded as a defect; Step S4: calibration of the laser scanning system (2): the laser scanning system (2) is started, the measuring light beam and the reference light beam are focused on the smooth and intact surface beside the defect point, the pressure and density of sulfur hexafluoride gas in the optical path adjuster are adjusted by the air compressor, the temperature of the sulfur hexafluoride gas is adjusted by the liquid nitrogen evaporation refrigeration system, the optical path difference is precisely adjusted, until a clear and stable interference image is obtained, and the image is set as a standard interference image; Step S5: accurately confirming the defect point: the laser scanning system (2) scans the defect point, collects multiple groups of measurement interference images, compares each group of measurement interference images with the standard interference image obtained in step S4, and when the interference image is detected to change beyond the set threshold value, the place is confirmed as a defect point; Step S6: associated defect extension detection: based on the pre-set defect probability association rule, the laser scanning system (2) moves to other defect positions associated with the currently confirmed defect point, and steps S5 to S6 are repeatedly executed to perform point scanning and confirmation.

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