A deep hole detection device and method based on light reflection

Abstract

This invention discloses a deep hole detection device and method based on light reflection, specifically relating to the field of deep hole optical detection technology. The device includes a light source assembly, an optical path separation assembly, a single-mode transmission and receiving optical fiber, a detection probe, a return light detection assembly, a processing and control unit, and a relative positioning scanning assembly. The detection probe includes a collimation assembly, a two-dimensional micro-deflection reflector, and a relay imaging assembly. During detection, the relative detection position of the local detection area remains unchanged, forming a complementary micro-deflection state along two adjustment directions, so that the effective illumination areas of different incident directions overlap in a predetermined manner. Back-coupling optical power is obtained through the same single-mode transmission and receiving optical fiber to form a normalized differential momentum, searching for two-dimensional reflection balance, and determining the corresponding two-dimensional center deflection parameter as the local reflection balance parameter, thereby improving the stability and reliability of deep hole inner wall detection.

Description

Technical Field

[0001] This invention relates to the field of deep hole optical inspection technology, and more specifically, to a deep hole inspection device and method based on light reflection. Background Technology

[0002] Deep holes are widely used in aerospace, equipment manufacturing, and precision mechanical parts. The machining condition of their inner walls directly affects the fitting accuracy and reliability of the parts. Due to the characteristics of deep holes, such as large hole depth and limited internal space, conventional contact inspection tools are difficult to continuously obtain the hole wall condition. Therefore, non-contact optical inspection methods that use inspection light to illuminate the hole wall and collect the reflected information have become an important technical means for deep hole inspection.

[0003] Existing invention patent CN102062586B proposes an internal hole laser measurement device. This device illuminates the inner surface of the hole under test with a laser, and the reflected light is imaged onto a CCD via a prism and lens. The hole depth or diameter information is obtained based on the centroid shift of the light spot, thus reducing the influence of factors such as inner wall roughness and cleanliness when simply measuring using reflected light intensity. However, this method mainly establishes the geometric measurement relationship of hole depth or diameter based on the positional change of the reflected light spot. Its detection object is the internal hole size parameter. For situations where changes in reflection amplitude and local reflection direction simultaneously cause signal changes in the detection of local anomalies in the hole wall, there is still a lack of corresponding characterization of the local reflection state.

[0004] Existing invention patent CN117804357B proposes a deep hole detection device and method based on laser reflection. This method uses a ring laser to irradiate the inner wall of a deep hole, and a conical internal mirror guides the reflected light to a screen to form a ring-shaped spot. Parameters such as hole diameter, roundness, and cylindricity are obtained based on the spot size, and the spot boundary state can also reflect the roughness of the hole wall. However, this method mainly relies on the size of the reflected spot and image features for detection. For finely machined deep hole inner walls, cleaning residue, thin layers of oil, processing texture, and differences in local reflectivity can all alter the reflection response. When these factors coexist with local surface changes such as scratches, pits, and burrs, a single reflection response is insufficient to stably characterize the local reflection state of the hole wall.

[0005] Therefore, there is an urgent need in this field for a deep hole detection technology that can stably characterize the local reflection state of the inner wall of a deep hole and reduce the interference of non-geometric reflection amplitude changes on the detection results. Summary of the Invention

[0006] To overcome the aforementioned deficiencies of the prior art, the present invention provides a deep hole detection device and method based on light reflection. By keeping the local detection area unchanged during the reflection balance search, the complementary micro-deflection state is repeatedly sampled with predetermined overlap in the same local detection area at different incident directions. The normalized differential momentum is formed by using the back-coupling optical power of the same single-mode transmission and receiving optical fiber to determine the local reflection balance parameters corresponding to the two-dimensional reflection balance, thereby solving the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A deep hole detection device based on light reflection includes a light source assembly 1, an optical path separation assembly 2, a single-mode transmission and reception optical fiber 3, a detection probe 4, a return light detection assembly 5, and a processing and control unit 6. The optical path separation assembly 2 is used to separate the detection light and the return light. The detection probe 4 includes a collimation assembly 41, a two-dimensional micro-deflection reflector 42, and a relay imaging assembly 43. The two-dimensional micro-deflection reflector 42 forms a first micro-deflection state and a second micro-deflection state with equal amplitude and opposite direction to the center deflection state in two adjustment directions, respectively. The relay imaging assembly 43 causes the first micro-deflection state and the second micro-deflection state in the same adjustment direction to irradiate the inner wall of the deep hole of the workpiece 8 under test with different incident directions, and the corresponding... The effective irradiation area overlaps with the same local detection area 81; during the reflection balance search, the relative detection position of the detection probe 4 and the workpiece 8 remains unchanged; the single-mode transmission receiving fiber 3 transmits the detection light and receives the return light reflected from the local detection area 81, propagated in the reverse direction through the detection probe 4, and recoupled; the return light detection component 5 detects the return light power, and the processing control unit 6 uses the ratio of the difference between the return light power of the first micro-deflection state and the second micro-deflection state in the same adjustment direction to the sum as the normalized differential momentum, adjusts the center deflection state until the absolute values ​​of the two normalized differential momentum are not greater than the preset balance threshold, forms a candidate reflection balance state, and determines the corresponding two-dimensional center deflection parameter confirmed by the reflection balance as the local reflection balance parameter.

[0008] As a further embodiment of the present invention, the detection device further includes a relative positioning scanning component 7, which is used to keep the relative detection position of the detection probe 4 and the workpiece 8 under test unchanged during the reflection balance search, and to transfer to the next local detection area 81 after forming the current local detection result.

[0009] As a further aspect of the present invention, when the sum of the back-coupling optical power of the two states in the same adjustment direction is lower than a set threshold, the processing control unit 6 searches for an effective response region; only when the normalized differential momentum on both sides of the candidate reflection balance state forms a sign change consistent with the calibrated zero-crossing direction, and there is only one stable zero-crossing interval within the predetermined verification interval, the local reflection balance parameter is output; otherwise, the reflection balance invalid state is output.

[0010] As a further embodiment of the present invention, the relay imaging component 43 images the beam action area of ​​the two-dimensional micro-deflection reflector 42 onto the local detection area 81, so that the ratio of the overlapping area of ​​the two effective irradiation areas corresponding to the first and second micro-deflection states to the smaller area therein is not less than 80%.

[0011] As a further aspect of the present invention, the processing control unit outputs local reflection balance parameters only when the normalized differential momentum on both sides of the candidate reflection balance state forms a sign change consistent with the calibrated zero-crossing direction, and when there is only one stable zero-crossing interval within the predetermined verification interval; the stable zero-crossing interval is the interval in which the sign change is formed between the same pair of adjacent verification center deflection states when three complete verification samples are executed consecutively, otherwise the reflection balance invalid state is output.

[0012] As a further aspect of the present invention, the micro-deflection states of the two adjustment directions are collected sequentially in time through the same single-mode transmission and receiving optical fiber and the same return light detection component; after each state switch of the two-dimensional micro-deflection reflector, the return optical power is obtained after a pre-calibrated stabilization time.

[0013] As a further aspect of the present invention, the processing control unit stores a background calibration grid established under the condition of blocking the effective return light. The background calibration grid records the background back-coupling power corresponding to different micro-deflection states of the two-dimensional micro-deflection reflector. During formal testing, the original back-coupling power is subtracted from the background based on the background back-coupling power corresponding to the current micro-deflection state, and the normalized differential is calculated based on the back-coupling power after background subtraction.

[0014] As a further aspect of the present invention, the processing control unit searches for two center deflection parameters with opposite signs in the two adjustment directions, and gradually narrows the search range within the formed opposite-sign interval; the two adjustment directions are adjusted alternately, and each time any center deflection parameter is changed, the back-coupling optical power of each micro-deflection state in the two adjustment directions is obtained again and the normalized differential is calculated. After the center deflection parameter in the other adjustment direction is changed, it is reconfirmed whether the two ends of the original opposite-sign interval still maintain opposite signs. When the opposite-sign relationship fails, the opposite-sign interval is re-established.

[0015] This invention also provides a deep hole detection method based on light reflection, comprising the following steps: Step 1: Position the detection probe in the local detection area of ​​the deep hole inner wall of the workpiece to be tested, set the center deflection state of the two-dimensional micro-deflection reflector and keep the relative detection position unchanged; Step 2: Along the first adjustment direction, with the current center deflection state as the reference, form a first micro-deflection state and a second micro-deflection state with equal amplitude and opposite direction. The effective illumination areas of the two states are overlapped in the same local detection area through the relay imaging component. The back-coupling optical power of the two states is obtained through the same single-mode transmission and receiving optical fiber, and the ratio of their difference to their sum is used as the first normalized differential momentum. Step 3: Along the second adjustment direction, based on the current center deflection state, form a first micro-deflection state and a second micro-deflection state with equal amplitude and opposite direction, and obtain the second normalized differential momentum in the same way as in Step 2. Step 4: Adjust the center deflection state according to the first and second normalized differential momentum, and repeat steps 2 and 3 until the absolute values ​​of both are not greater than the preset equilibrium threshold, thus forming a candidate reflection equilibrium state. Step 5: Validity of candidate reflection balance states is determined, and the confirmed two-dimensional center deflection parameters are identified as local reflection balance parameters and transferred to the next local detection area 81.

[0016] As a further aspect of the present invention, in steps two and three, when the sum of the back-coupling optical power of the two states in the same adjustment direction is lower than a set threshold, the center deflection state is changed within a predetermined search interval to search for an effective response region; in step five, the reflection balance state is determined only when the normalized differential momentum on both sides of the candidate reflection balance state forms a sign change consistent with the calibrated zero-crossing direction, and there is only one stable zero-crossing interval within the predetermined verification interval; otherwise, it is determined as an invalid reflection balance state.

[0017] The technical effects and advantages of the deep hole detection device and method based on light reflection of this invention are as follows: This invention achieves deep hole detection by ensuring that "the ratio of the overlapping area of ​​the two effective illumination areas to the smaller area is not less than 80%" and "the sign change is consistent with the calibration zero-crossing direction + there is only one stable zero-crossing interval in the predetermined verification interval." Furthermore, it achieves deep hole detection through "fixed position, complementary micro-deflection in two directions, more than 80% overlap of illumination areas, backcoupling with the same single-mode fiber, difference and sum normalization, and two-dimensional unique stable zero-crossing." This invention enables the same local detection area to maintain a relatively consistent spatial sampling range under different micro-deflection states, reducing the local reflection differences of the hole wall introduced by changes in the detection spot position, and improving the comparability between reflection responses from different incident directions and the repeatability of local detection results. The normalized differential momentum obtained by this invention mainly reflects the relative backcoupling relationship between two complementary detection states. When the two states are affected by approximately the same changes in light source power, local reflection capability, and common optical path loss, the influence of their common multiplicative amplitude change on the reflection equilibrium position is reduced, resulting in better amplitude stability of the detection results compared to single absolute backcoupling optical power. This invention uses the center deflection parameters corresponding to the two-dimensional reflection balance to form local reflection balance parameters, enabling deep hole inner wall detection to obtain local reflection state information that is different from the single absolute back-coupling optical power. For regions with insufficient return signals, unstable reflection responses, or non-unique balances, an invalid reflection balance state is formed, avoiding the forced use of responses without stable physical correspondence as valid detection results. This improves the reliability of deep hole inner wall anomaly detection and reduces the risk of misjudgment caused by non-geometric factors such as cleaning residues and changes in local reflection capabilities. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a deep hole detection device based on light reflection according to the present invention; Figure 2 This is a schematic diagram of the complementary micro-deflection reflection balance detection principle of the detection probe of the present invention.

[0019] In the diagram: 1. Light source assembly; 2. Optical path separation assembly; 3. Single-mode transmission and receiving optical fiber; 4. Detection probe; 41. Collimation assembly; 42. Two-dimensional micro-deflection reflector; 43. Relay imaging assembly; 44. Protective window; 5. Return light detection assembly; 6. Processing and control unit; 7. Relative positioning scanning assembly; 8. Workpiece to be tested; 81. Local detection area. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1

[0022] This embodiment provides a deep hole detection device and method based on light reflection for detecting the inner wall of a precision-machined deep hole with detectable directional reflection components. During detection, the limited area actually covered by the detection light on the inner wall of the deep hole of the workpiece 8 is designated as a local detection area 81. While maintaining the relative detection position corresponding to the current local detection area 81, the two-dimensional micro-deflection reflector 42 is controlled to form a first micro-deflection state and a second micro-deflection state, opposite to the direction of the center deflection state, along two adjustment directions. The back-coupling optical power of each state is sequentially obtained by the same single-mode transmission and receiving optical fiber 3. The processing control unit 6 generates a normalized differential based on the back-coupling optical power of the two states in the same adjustment direction and adjusts the center deflection state. After the normalized differential in both adjustment directions satisfies the preset balance condition, a candidate reflection balance state is formed. After verifying the effectiveness of the reflection balance, the corresponding two-dimensional center deflection parameter is determined as the local reflection balance parameter of the current local detection area 81.

[0023] like Figure 1 As shown, the deep hole detection device based on light reflection in this embodiment includes a light source assembly 1, an optical path separation assembly 2, a single-mode transmission and reception optical fiber 3, a detection probe 4, a return light detection assembly 5, a processing and control unit 6, and a relative positioning scanning assembly 7. The workpiece 8 to be tested is a metal workpiece with a precision-machined deep hole. The nominal diameter of the deep hole is 18mm, and the effective detection depth is 150mm. The detection probe 4 is a slender rod-shaped structure with an outer diameter of 8mm and an effective insertion length of 180mm. The relative positioning scanning assembly 7 changes the detection position by feeding the detection probe 4 along the axial direction of the deep hole and rotating the workpiece 8 around the axis of the deep hole. After a local detection area 81 is detected, the relative positioning scanning assembly 7 stops axial feeding and circumferential rotation. From the time the return light power of the current area is first obtained until the local detection result is formed, the relative detection position between the detection probe 4 and the workpiece 8 remains unchanged.

[0024] The light source assembly 1 uses a single-mode coupled low-coherence light source with a center wavelength of 1310nm, and the detection light power coupled into the single-mode transmission and receiving fiber 3 is adjusted to approximately 2mW. The optical path separation assembly 2 uses a three-port fiber optic circulator; its input end is connected to the light source assembly 1, its common end is connected to the single-mode transmission and receiving fiber 3, and its return end is connected to the return light detection assembly 5. This circulator is used to send the detection light into the single-mode transmission and receiving fiber 3 and guide the return light to the return light detection assembly 5. The return light detection assembly 5 uses a photodetector matched to the 1310nm band and sends the detection signal corresponding to the return light power to the processing and control unit 6. The micro-deflection states in both adjustment directions are acquired sequentially over time through the same single-mode transmission and receiving fiber 3 and the same return light detection assembly 5.

[0025] like Figure 2 As shown, the front end of the detection probe 4 is sequentially arranged with a collimation component 41, a two-dimensional micro-deflection reflector 42, a relay imaging component 43, and a protective window 44 along the direction of detection light propagation. The collimation component 41 forms the detection light output from the single-mode transmission and receiving fiber 3 into a near-collimated beam with a diameter of approximately 0.20 mm. The two-dimensional micro-deflection reflector 42 is a biaxial micromirror with an effective reflecting surface diameter of approximately 1 mm. Its installation posture directs the detection light propagating along the axis of the detection probe 4 in the center deflection state towards the inner wall of the deep hole. The usable mechanical deflection range of the two-dimensional micro-deflection reflector 42 in both adjustment directions at least covers... to The search range for the center deflection state used to determine the local reflection equilibrium parameters is limited to... to The first and second micro-deflection states, relative to the current center deflection state, employ equal-amplitude, opposite-direction mechanical micro-deflection. The complementary detection micro-deflection amount in the first adjustment direction is denoted as... The second adjustment direction is denoted as In this embodiment The actual change in the incident direction at the aperture wall is determined by the angular calibration relationship after the detection probe 4 is installed and adjusted, and the mechanical deflection of the micro-mirror is not directly used as the incident angle at the aperture wall.

[0026] In this embodiment, "equal amplitude and opposite direction" means that in the same adjustment direction, the absolute changes in the mechanical deflection parameters of the two-dimensional micro-deflection reflector in the first micro-deflection state and the second micro-deflection state relative to the current center deflection state are equal but opposite in sign. The actual incident direction corresponding to the hole wall is determined by the angle calibration relationship after the detection probe is installed and adjusted. It is not required that the mechanical deflection of the two-dimensional micro-deflection reflector be directly equal to the actual change in the incident angle at the hole wall.

[0027] The relay imaging component 43 is positioned between the two-dimensional micro-deflector 42 and the protective window 44. It consists of two near-infrared microlenses with an equivalent focal length of approximately 2.1 mm, an equivalent object distance of approximately 3.5 mm, and a nominal image distance of approximately 5.5 mm. During assembly and adjustment, the axial position of the relay imaging component 43 and the lens spacing are adjusted so that the detection beam action area at the two-dimensional micro-deflector 42 and the local detection area 81 form a predetermined imaging relationship. The effective illumination area is defined as the light intensity distribution obtained by calibrating the microscopic imaging device, which includes the peak position and whose light intensity is not lower than the peak light intensity. The continuous region is determined, and the center of the light spot is determined using the intensity centroid of the effective irradiation area. The areas of the effective irradiation areas corresponding to the first and second micro-deflection states are denoted as follows: and The overlapping area of ​​the two effective irradiation areas is denoted as Its overlap rate for: In the formula, and These represent the areas of the effective irradiation regions in the first and second micro-deflection states, respectively. The area of ​​overlap between the two effective irradiation areas. The effective irradiation area overlap rate. This embodiment uses... As a predetermined overlap condition.

[0028] After assembly and adjustment, the effective light spot The intensity diameter is 0.29–0.31 mm; the center-to-center distance between the two complementary micro-deflection states in the first adjustment direction is 0.036 mm, and in the second adjustment direction it is 0.039 mm. Calculated using two circular effective irradiation areas with a diameter of 0.30 mm and a center-to-center distance of 0.04 mm, the overlapping area accounts for approximately 83.1% of the smaller area, satisfying the predetermined overlap condition. Therefore, although the first and second micro-deflection states change the incident direction of the detection light at the aperture wall, the main spatial sampling range of the two states still corresponds to the same local detection area 81. The protective window 44 uses a 0.5 mm thick near-infrared anti-reflection quartz window and is set approximately [missing information - likely a measurement] relative to the detection light in the center-deflection state. The tilt angle is adjusted to reduce direct reflections from the surface of the protective window 44 and recouple it into the single-mode transmission and receiving fiber 3.

[0029] The returned light generated in the local detection region 81 passes sequentially through the protective window 44, the relay imaging component 43, the two-dimensional micro-deflection reflector 42, and the collimation component 41 before being recoupled into the single-mode transmission and receiving fiber 3. When the propagation direction, lateral position, and wavefront state of the returned light change, the degree of matching between it and the guided mode field of the single-mode transmission and receiving fiber 3 changes, thereby causing a change in the back-coupled light power detected by the returned light detection component 5. Therefore, the back-coupled light power of each micro-deflection state is used to characterize the return coupling state of the current local detection region 81 under the corresponding incident direction of the detection light.

[0030] After the device is assembled and adjusted, the beam overlap calibration, angle calibration, and reflection balance zero-crossing direction calibration are performed. The reflection calibration component is set at the same working distance as the inner wall of the deep hole to be measured. The two center deflection parameters of the two-dimensional micro-deflection reflector 42 are changed respectively, according to the aforementioned... The intensity boundary obtains the effective irradiation area, intensity centroid, and intensity centroid of each micro-deflection state. By adjusting the relay imaging component 43, both adjustment directions are satisfied. Then, the center deflection state is moved from one side of the reflection equilibrium position through the equilibrium position to the other side. The order of sign changes of the normalized differential in the two adjustment directions is recorded, and this order is determined as the calibration zero-crossing direction of the corresponding adjustment direction.

[0031] To ensure that the local reflection balance parameters obtained from different testing batches have consistent coordinate meanings, the reflection calibration component is also set along two adjustment directions during angle calibration. , , , and Complete complementary micro-deflection sampling and reflection balance search are performed at each tilt angle position, and the corresponding two-dimensional center deflection parameters are recorded. This establishes the correspondence between the center deflection parameters of the two-dimensional micro-deflection reflector 42 and the reflection direction of the calibration component. When testing the workpiece 8, local reflection balance parameters are directly saved without being forcibly converted to the absolute normal of the ideal hole wall. When comparisons are needed between different devices, the above calibration relationship is used to convert them to a unified reflection direction coordinate system.

[0032] During the assembly and adjustment process, state-related background backcoupling data is simultaneously established. The effective return light generated by the reflective calibration element is blocked. Within the usable mechanical deflection range of −1.0° to +1.0° in the two adjustment directions of the two-dimensional micro-deflection reflector 42, the background backcoupling power for each two-dimensional micro-deflection state is recorded at 0.10° intervals to establish a background calibration grid. The original backcoupling power for a given actual micro-deflection state is denoted as... The background backcoupling optical power corresponding to this state is denoted as . The backcoupling optical power that participates in subsequent processing for: In the formula, The original back-coupling optical power is directly obtained from the return light detection component 5. The background backcoupling power corresponds to the micro-deflection state. This represents the back-coupling optical power after background subtraction. When the actual state lies between background calibration grid nodes, it is obtained by bilinear interpolation based on adjacent grid nodes. .

[0033] After background calibration, 100 pairs of background residuals were continuously collected using the sampling method of formal testing, with the effective return light blocked. The standard deviation of the sum of the background residual powers of the two complementary states in each pair was calculated. And will set a threshold Set to: In the formula, The standard deviation of the sum of paired background residual powers. A threshold is set for the backcoupling optical power to determine whether the current center deflection state is within the effective response zone. The sum of the backcoupling optical power after background subtraction for two micro-deflection states in the same adjustment direction is not less than [a certain threshold]. At that time, the processing control unit 6 calculates the corresponding normalized differential.

[0034] During formal testing, the relative positioning scanning component 7 positions the detection probe 4 to the current local detection area 81 and stops moving. The two-dimensional center deflection parameter during round search is denoted as ,in The center deflection parameter is the first adjustment direction. This refers to the center deflection parameter in the second adjustment direction. In the first adjustment direction, the two-dimensional micro-deflection reflector 42 sequentially enters... and Two complementary micro-deflection states are used. After each state transition, a pre-calibrated settling time is waited for. In this embodiment, the settling time of the two-dimensional micro-deflection reflector 42 is 1.5 ms. Subsequently, multiple detection values ​​are continuously acquired within a 1 ms sampling time and averaged to obtain the backcoupling optical power after background subtraction. and .when: At that time, the first normalized differential momentum for: In the formula, and These are the backcoupling optical powers in the first and second micro-deflection states of the first adjustment direction, respectively. This is the first normalized differential momentum.

[0035] The second adjustment direction uses the same method, allowing the two-dimensional micro-deflection reflector 42 to enter sequentially. and Obtain the backcoupling optical power after background subtraction. and .when: At that time, the second normalized differential momentum for: In the formula, and These represent the backcoupling optical power in the first and second micro-deflection states of the second adjustment direction, respectively. This is the second normalized differential momentum. , , and All data were obtained in chronological order from the same single-mode transmission and reception fiber 3 and the same return light detection component 5.

[0036] All four-state sampling in the same local detection area 81 is completed after the relative positioning scanning component 7 stops. Based on the stabilization and sampling times of this embodiment, the basic sampling time for one round of sampling for the two complementary states in each of the first and second adjustment directions is approximately 10ms. Only after this is the center deflection state changed according to the obtained normalized differential momentum. Therefore, each complementary state spatially corresponds mainly to the same local detection area 81, and temporally they are also adjacent in their acquisition. After the center deflection state changes, four back-coupling optical powers are reacquired, without using the data from the previous center deflection state.

[0037] While maintaining a constant working distance on the reflective calibration component, the center deflection state in the first adjustment direction is changed, and the center deflection state is fixed at the relative reflection equilibrium position. The input optical power was changed at different times, and the resulting feedback response data are shown in Table 1.

[0038] Table 1. Recoupling response data under different center deflection states and input optical power conditions. Center deflection relative to equilibrium position / ° Input optical power ratio / % First micro-deflection state reflux optical power / μW Second micro-deflection state hysteresis power / μW Normalized differential momentum -0.08 100 20.02 10.55 0.310 -0.04 100 19.14 13.92 0.158 0 100 17.06 17.08 -0.001 0.04 100 13.95 19.20 -0.158 0.08 100 10.55 20.01 -0.310 0.04 80 11.17 15.34 -0.157 0.04 60 8.36 11.50 -0.158 As shown in Table 1, when the center deflection state moves from one side of the reflection equilibrium position to the other, the first normalized differential momentum changes from a positive value to a negative value after passing through a position close to zero. The direction of adjustment for the center deflection parameter can be determined based on its sign. The center deflection state remains... When the input optical power decreases from 100% to 80% and 60%, the backcoupling optical power in both micro-deflection states decreases simultaneously, while the first normalized differential momentum is -0.158, -0.157, and -0.158, respectively, with a maximum change of 0.001. This result indicates that when the first and second micro-deflection states mainly act on the same local detection region 81 and the backcoupling optical power in both states undergoes a common amplitude change, the ratio of the difference to the sum maintains the relative backcoupling relationship between the two states.

[0039] When the sum of the backcoupling optical power in the current two states is less than 1000 rpm in any adjustment direction At this time, the processing control unit 6 enters the effective response area search, but does not immediately determine that the current local detection area 81 is in an invalid reflection balance state. The first local detection area 81 is in both adjustment directions with to The predetermined search interval, as the center deflection parameter, is used to... A two-dimensional coarse search is performed using the step size; the sum of the back-coupled optical power is found to reach the desired level. After the area, in the vicinity of that area The step size is used to obtain the normalized differential momentum. Adjacent local detection regions 81 are preferentially used with the local reflection balance parameters of the previous effective local detection region as the initial center deflection state, and a predetermined search interval is established in their vicinity. If there are no preceding effective parameters, the search is performed in the same manner as the first local detection region. If no effective response is obtained or no change in the sign of the normalized differential momentum is formed, the search range is gradually expanded until coverage is achieved. to If no effective response is obtained or a normalized differential momentum sign change is formed after expansion in any adjustment direction, the current local detection area 81 is determined to be in an invalid reflection balance state.

[0040] After obtaining the effective response region, the processing control unit 6 searches for two center deflection parameters with opposite signs of normalized differential momentum in the two adjustment directions, and gradually narrows the search range within the resulting intervals of opposite signs. In this embodiment, the center deflection parameters are updated using the midpoint of the interval. The endpoints of the intervals of opposite signs in the first adjustment direction are denoted as... and The intermediate parameter is: The endpoints of the opposite-sign interval in the second adjustment direction are denoted as... and The intermediate parameter is: In the formula, , These are the two endpoints of the interval with opposite signs in the first adjustment direction. Let be the midpoint of its interval; , These are the two endpoints of the interval with opposite signs in the second adjustment direction. The midpoint of its interval is used. The two adjustment directions are adjusted alternately, and the value is re-acquired each time the center deflection parameter changes. , , and And calculate , After the center deflection parameter of the other adjustment direction is changed, reconfirm whether the two ends of the original opposite sign interval still maintain opposite signs. If the opposite sign relationship fails, re-establish the opposite sign interval according to the current other adjustment direction parameter.

[0041] The preset balance threshold is denoted as In this embodiment, the following is taken: when: and: At that time, the current center deflection state is taken as the candidate reflection equilibrium state. In the formula, The allowable normalized differential momentum balance error. The maximum number of alternating adjustments in a single local detection area of ​​81. Set to 20 times. This indicates the maximum number of two-dimensional center deflection adjustment rounds allowed to be executed in the current local detection area 81; reaching... It still couldn't be made and When the preset balance threshold is met, the current local detection area 81 is determined to be in an invalid reflection balance state.

[0042] After the candidate reflection equilibrium state is formed, its effectiveness is verified. The deflection parameter of the candidate center in the first adjustment direction is denoted as... The deflection parameter of the candidate center in the second adjustment direction is denoted as The balance verification offset is denoted as In this embodiment, .by Set as center , , and The four verification centers deflected states, and the method was still used in each verification center state. Complementary detection of micro-deflection to regain backcoupling optical power and The second adjustment direction is to Using the same method around the center, and with regain The center deflection parameter is located at When searching the boundary, verify the maximum offset of the center. Then superimposed Complementary detection of micro-deflection, with a maximum mechanical deflection of It remains within the usable mechanical deflection range of the two-dimensional micro-deflection reflector 42.

[0043] A stable zero-crossing interval refers to a normalized differential momentum sign change consistent with the calibrated zero-crossing direction that occurs between the same pair of adjacent verification center deflection states during three consecutive complete verification samplings. If only one stable zero-crossing interval is detected within a predetermined verification interval for an adjustment direction, that adjustment direction passes validity verification; after both adjustment directions pass verification, the current two-dimensional center deflection parameters are set as follows: The parameters are determined as local reflection balance parameters. In the formula, These are the local reflection balance parameters for the current local detection area 81. and These are the center deflection parameters when effective reflection balance is achieved in the first and second adjustment directions, respectively. If a stable zero-crossing is not achieved in either adjustment direction, or if there are two or more mutually separate stable zero-crossing intervals within the predetermined verification interval, the reflection balance is determined to be invalid.

[0044] The processing control unit 6 simultaneously records the axial and circumferential positions corresponding to the current local detection area 81. For areas that pass the validity verification, the local detection result includes at least the stated positions and local reflection balance parameters. For areas that fail the validity verification, the local detection results record the location and the invalid reflection balance state. Therefore, the results obtained from subsequent scans can be arranged point by point according to the axial and circumferential positions of the deep hole, without replacing the local reflection balance parameters with the level of absolute backcoupling optical power at a certain time.

[0045] After completing the detection of the current local detection area 81, the relative positioning scanning component 7 changes its detection position. In this embodiment, the axial detection step size is 0.20 mm, and the circumferential detection step size is... For a deep hole with a diameter of 18mm, The corresponding borehole wall arc length is approximately 0.236 mm. Both the axial detection step distance and the circumferential arc length are less than the effective spot diameter of 0.29–0.31 mm, resulting in partial overlap between adjacent local detection areas 81 in both the axial and circumferential directions. The detection process proceeds in the following sequence: positioning, maintaining relative detection position, complementary micro-deflection sampling, effective response zone search, two-dimensional reflection balance search, validity verification, recording local detection results, and moving to the next local detection area 81, until the deep borehole inner wall detection is completed.

[0046] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A deep hole detection device based on light reflection, characterized in that, The system includes a light source assembly (1), an optical path separation assembly (2), a single-mode transmission and receiving optical fiber (3), a detection probe (4), a return light detection assembly (5), and a processing control unit (6). The optical path separation assembly (2) is used to separate the detection light from the return light. The detection probe (4) includes a collimation assembly (41), a two-dimensional micro-deflection reflector (42), and a relay imaging assembly (43). The two-dimensional micro-deflection reflector (42) forms a first micro-deflection state and a second micro-deflection state with equal amplitude and opposite direction in two adjustment directions, respectively, with the center deflection state as the reference. The relay imaging assembly (43) enables the two states in the same adjustment direction to irradiate the inner wall of the deep hole of the workpiece (8) under test with different incident directions, and the effective irradiation area overlaps with the same local detection area (81). During the reflection balance search, the relative detection position of the detection probe (4) and the workpiece (8) under test remains unchanged. The single-mode transmission receiving fiber (3) transmits detection light and receives the return light reflected from the local detection area (81), propagated in the opposite direction through the detection probe (4), and recoupled; the return light detection component (5) detects the return light power, and the processing control unit (6) takes the ratio of the difference and sum of the return light power of the two states in the same adjustment direction as the normalized differential momentum, adjusts the center deflection state until the absolute values ​​of the two normalized differential momentum are not greater than the preset balance threshold, forms a candidate reflection balance state, and determines the corresponding two-dimensional center deflection parameter confirmed by the reflection balance as the local reflection balance parameter.

2. The deep hole detection device based on light reflection according to claim 1, characterized in that, It also includes a relative positioning scanning component (7) for maintaining the relative detection position of the detection probe (4) and the workpiece (8) during the reflection balance search, and for moving to the next local detection area (81) after the current local detection result is formed.

3. The deep hole detection device based on light reflection according to claim 1, characterized in that, When the sum of the back-coupling optical power of the two states in the same adjustment direction is lower than the set threshold, the processing control unit (6) changes the center deflection state within the predetermined search interval to search for the effective response area; if no effective response is obtained or no normalized differential momentum sign change is formed, the search range is expanded; if no effective response is obtained or no normalized differential momentum sign change is formed after expansion, the reflection balance invalid state is output.

4. The deep hole detection device based on light reflection according to claim 1, characterized in that, The relay imaging component (43) images the beam action area of ​​the two-dimensional micro-deflection reflector (42) onto the local detection area (81), so that the ratio of the overlapping area of ​​the two effective irradiation areas corresponding to the first micro-deflection state and the second micro-deflection state to the smaller area is not less than 80%.

5. The deep hole detection device based on light reflection according to claim 1, characterized in that, The processing control unit (6) outputs local reflection balance parameters only when the normalized differential momentum on both sides of the candidate reflection balance state forms a sign change consistent with the calibrated zero-crossing direction, and there is only one stable zero-crossing interval within the predetermined verification interval; the stable zero-crossing interval is the interval in which the sign change is formed between the same pair of adjacent verification center deflection states when three complete verification samples are executed consecutively, otherwise the reflection balance invalid state is output.

6. The deep hole detection device based on light reflection according to claim 1, characterized in that, The micro-deflection states of the two adjustment directions are collected in chronological order through the same single-mode transmission receiving fiber (3) and the same return light detection component (5); after each state switch of the two-dimensional micro-deflection reflector (42), the return optical power is obtained after a pre-calibrated stabilization time.

7. The deep hole detection device based on light reflection according to claim 1, characterized in that, The processing control unit (6) stores a background calibration grid established under the condition of blocking the effective return light. The background calibration grid records the background back-coupling power corresponding to different micro-deflection states of the two-dimensional micro-deflection reflector (42). During formal testing, the original back-coupling power is subtracted from the background based on the background back-coupling power corresponding to the current micro-deflection state, and the normalized differential is calculated based on the back-coupling power after background subtraction.

8. The deep hole detection device based on light reflection according to claim 1, characterized in that, The processing control unit (6) searches for two center deflection parameters with opposite signs of normalized differential momentum in the two adjustment directions, and gradually narrows the search range within the formed opposite sign interval; the two adjustment directions are adjusted alternately, and after each change of any center deflection parameter, the back-coupling optical power of each micro-deflection state in the two adjustment directions is obtained again and the normalized differential momentum is calculated. After the center deflection parameter of the other adjustment direction is changed, it is reconfirmed whether the two ends of the original opposite sign interval still maintain opposite signs. When the opposite sign relationship fails, the opposite sign interval is re-established.

9. A deep hole detection method based on light reflection, characterized in that, include: Step 1: Position the detection probe (4) in the local detection area (81) of the deep hole inner wall of the workpiece (8) to be tested, set the center deflection state of the two-dimensional micro-deflection reflector (42) and keep the relative detection position unchanged; Step 2: Along the first adjustment direction, with the current center deflection state as the reference, form a first micro-deflection state and a second micro-deflection state with equal amplitude and opposite direction. Through the relay imaging component (43), make the effective illumination area of ​​the two states overlap in the same local detection area (81). Obtain the back-coupling optical power of the two states through the same single-mode transmission and receiving optical fiber (3), and use the ratio of their difference to the sum as the first normalized differential momentum. Step 3: Along the second adjustment direction, based on the current center deflection state, form a first micro-deflection state and a second micro-deflection state with equal amplitude and opposite direction, and obtain the second normalized differential momentum in the same way as in Step 2. Step 4: Adjust the center deflection state according to the first and second normalized differential momentum and repeat steps 2 and 3 until the absolute values ​​of both are not greater than the preset equilibrium threshold, thus forming a candidate reflection equilibrium state. Step 5: Validity of candidate reflection balance states is determined, and the confirmed two-dimensional center deflection parameters are determined as local reflection balance parameters and transferred to the next local detection area (81).

10. The deep hole detection method based on light reflection according to claim 9, characterized in that, In steps two and three, when the sum of the back-coupling optical power of the two states in the same adjustment direction is lower than the set threshold, the center deflection state is changed within the predetermined search interval to search for an effective response region. In step five, the reflection equilibrium state is determined only when the normalized differential momentum on both sides of the candidate reflection equilibrium state forms a sign change consistent with the calibrated zero-crossing direction, and there is only one stable zero-crossing interval within the predetermined verification interval; otherwise, it is determined as an invalid reflection equilibrium state.

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