Calibration method for installation error of laser interferometer

Abstract

The invention belongs to the technical field of laser interferometer calibration, and discloses a laser interferometer installation error calibration method comprising the following steps: environment preparation: setting temperature, humidity and vibration parameters of a laser interferometer calibration environment; optical element cleaning, wherein absolute ethyl alcohol and lens paper are used for wiping the optical elements, and the optical elements specifically comprise a laser transmitter, a receiver and a reflector; laser wavelength calibration; calibrating the straightness; calculating an Abbe error; cosine error calculation; and calculating a dead stroke error. According to the calibration method for the installation error of the laser interferometer, the measurement precision of the laser interferometer is effectively improved, the measurement result is more stable and accurate, and the strict requirement of a high-precision numerical control machine tool for displacement measurement precision is met; and meanwhile, the method also has good universality and effectiveness in a complex curved surface measurement scene, and the measurement precision of the laser interferometer in a complex application environment can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of laser interferometer calibration technology, and in particular to a calibration method for installation errors of laser interferometers. Background Technology

[0002] Laser interferometers, with their high-precision measurement characteristics, are widely used in numerous fields such as industrial manufacturing, aerospace, and scientific research. For example, they play a crucial role in machine tool precision inspection and calibration, aircraft component assembly and inspection, and optical component inspection. However, laser interferometers are prone to various errors during installation, which can severely affect the accuracy and reliability of their measurements, thus adversely impacting production and research work in related fields.

[0003] Currently, there are various calibration methods for installation errors in laser interferometers, but all have certain limitations. Traditional calibration methods often rely on manual operation and physical gauge blocks, which are inefficient and easily affected by human factors, leading to significant errors in the calibration results. For example, when calibrating a laser interferometer using gauge blocks, the precision error of the gauge blocks themselves, as well as operational errors by the operator during installation and measurement, will all result in inaccurate calibration results. Moreover, this method is difficult to comprehensively and effectively calibrate complex installation errors, such as those involving multiple errors simultaneously.

[0004] While some software-based calibration methods improve the automation of calibration to some extent, their accuracy remains limited due to inherent limitations of the algorithms and their adaptability to different measurement environments. These algorithms are typically designed based on specific models and assumptions; when the actual measurement environment differs from these model assumptions, the calibration effect is significantly reduced. For example, in situations where environmental factors such as temperature and humidity vary considerably, software calibration methods based on fixed models may fail to accurately compensate for the impact of environmental factors on the measurement accuracy of laser interferometers.

[0005] Some calibration methods are complex to operate, requiring specialized technicians and expensive equipment. This not only increases calibration costs but also limits their adoption in actual production and application. For example, some high-precision calibration equipment requires specific constant temperature, humidity, and vibration-proof environments, which are difficult to meet in many production sites. Moreover, operating this equipment requires professional training and skills, increasing the difficulty of use and labor costs.

[0006] In conclusion, existing laser interferometer installation error calibration methods cannot meet the current demand for high-precision measurements. Developing a more comprehensive, efficient, accurate, and easy-to-operate calibration method is urgently needed and has significant practical and application value. Summary of the Invention

[0007] The purpose of this invention is to provide a calibration method for installation errors of laser interferometers, which solves the problems of low efficiency, limited accuracy, and complex operation of existing calibration methods. By systematically calibrating various errors generated during the installation of laser interferometers, the measurement accuracy of laser interferometers is effectively improved, enabling them to be applied more accurately in fields with extremely high measurement accuracy requirements, such as industrial manufacturing, aerospace, and scientific research experiments, thus ensuring the accuracy and reliability of production and research work.

[0008] To achieve the above objectives, the present invention provides a calibration method for the installation error of a laser interferometer, comprising the following steps: Step S1, Environmental Preparation: Set the temperature, humidity, and vibration parameters of the laser interferometer calibration environment; Step S2, cleaning optical components: Wipe the optical components, including the laser emitter, receiver and reflector, with anhydrous ethanol and lens paper; Step S3: Laser wavelength calibration; Step S4: Straightness calibration; Step S5: Abbe error calculation; Step S6: Calculate the cosine error; Step S7: Calculate dead travel error.

[0009] Preferably, in step S1, the temperature is controlled within the range of 20℃±2℃; and the ambient humidity is maintained within the range of 40%-60%. Use vibration isolation platforms to reduce the impact of ground vibration and vibration generated by equipment operation; when placing vibration isolation platforms, ensure that they are level and keep a distance from surrounding equipment to reduce interference from vibration sources.

[0010] Preferably, in step S3, a known length etalon is used as a reference, the laser interferometer is started, the laser is allowed to pass through the reference etalon, and the number of interference fringes of the laser at the standard length is measured; based on the principle of laser interference, multiple sets of data are obtained by measuring multiple standard lengths, and the actual wavelength of the laser is calculated using a data processing algorithm; When the measured laser wavelength deviates from the theoretical value, the laser wavelength is adjusted using the adjustment device of the laser interferometer.

[0011] Preferably, in step S4, the device under test is mounted on a linear guide rail, and the reflector of the laser interferometer is fixed at the end of the device under test; the position of the laser emitter is adjusted so that the laser beam is parallel to the linear guide rail of the device under test; then, the device under test is moved so that the reflector reciprocates along the linear guide rail. During the movement of the device under test, the laser interferometer collects interference fringe data and converts it into displacement data; by analyzing the displacement data, the straightness error of the linear guide rail of the device under test is obtained. When the straightness error exceeds the allowable range, the error can be reduced by adjusting the installation position or mechanical structure of the equipment under test.

[0012] Preferably, in step S5, the Abbe error calculation formula is: ; in, Indicates Abbe error; This indicates the offset distance between the installation height of the measuring optical lens assembly and the motion axis of the device under test; This indicates the angular motion error generated by the tested device during its movement.

[0013] Preferably, in step S6, the cosine error calculation principle is based on the difference between the measured distance and the actual movement distance when the laser beam path is not collimated with the measured axis; Let the angle between the laser beam and the axis being measured be . The actual distance traveled was The measured distance is The approximate calculation formula is: ; Therefore, the cosine error is: ; in, This represents the cosine error.

[0014] Preferably, in step S7, the cause of the dead path error is that during the linear measurement process, there is an optical path difference between the two coherent lights of the laser interferometer at the zero position, i.e., the dead path. After the measurement system is calibrated, changes in environmental conditions will cause changes in the laser wavelength, and the dead path part will not be compensated. Let the dead process length be The wavelength of a laser in a vacuum is The actual wavelength under the influence of environmental factors is The dead-path error is: ; in, This indicates the dead-path error.

[0015] Therefore, the present invention employs the above-mentioned calibration method for installation error of a laser interferometer, and the beneficial effects are as follows: (1) In terms of improving measurement accuracy, this invention comprehensively and systematically calibrates various errors generated during the installation of the laser interferometer, such as Abbe error, cosine error, and dead-path error. This effectively eliminates or reduces the impact of these errors on the measurement results, significantly improving the measurement accuracy of the laser interferometer. Compared with traditional calibration methods, it can more accurately measure physical quantities such as displacement, length, and angle of objects, meeting the high-precision measurement needs of fields such as industrial manufacturing, aerospace, and scientific research experiments.

[0016] (2) In terms of reducing calibration costs, this invention avoids reliance on expensive physical gauge blocks and complex specialized equipment. Through reasonable environmental control, cleaning of optical components, error calculation based on the principle of light wave interference, and calibration strategies, it reduces equipment and labor costs in the calibration process. At the same time, due to the improved measurement accuracy, it reduces product rework and scrap caused by measurement errors, thereby indirectly reducing production costs.

[0017] (3) In terms of simplifying the operation process, the present invention provides clear and specific calibration steps and calculation methods. Operators only need to follow the steps of environmental preparation, optical component cleaning, laser wavelength calibration, and straightness calibration, and use the corresponding calculation formulas to calculate and adjust the error. No complicated professional skills and experience are required, which reduces the difficulty of operation and improves the calibration efficiency.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a flowchart of a calibration method for installation errors in a laser interferometer. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] This invention discloses a calibration method for installation errors in laser interferometers, based on the principle of optical wave interference. A laser interferometer splits a laser beam into a reference beam and a measurement beam. When the measurement beam encounters a displacement or other change in the object being measured, its optical path changes. When the reference beam and the changed measurement beam reunite, interference fringes are generated due to the optical path difference. By accurately analyzing the changes in the interference fringes, physical quantities such as the object's displacement, length, and angle can be obtained.

[0022] Therefore, during the installation error calibration process, this principle is used to detect the installation error of the laser interferometer by analyzing abnormal changes in the interference fringes, specifically including Abbe error, cosine error, dead path error, etc.

[0023] For Abbe error, because the measuring optical lens group and the motion axis of the device under test are not aligned, angular motion error will cause the interference fringes to change in a specific pattern when the device moves. The magnitude of the Abbe error can be calculated by analyzing this pattern. For cosine error, the misalignment of the laser beam path with the measured axis will cause the change in interference fringes to mismatch with the actual displacement. The cosine error can be determined by comparing the theoretical and actual changes in interference fringes. Dead path error is related to changes in laser wavelength caused by environmental factors. The dead path error can be calculated by monitoring changes in environmental factors and the changes in interference fringes at zero position.

[0024] Based on the calculation results of these errors, corresponding adjustment and compensation measures are taken to calibrate the installation errors, thereby improving the measurement accuracy of the laser interferometer.

[0025] like Figure 1 As shown, the present invention provides a calibration method for the installation error of a laser interferometer, the specific implementation process of which is as follows: Step S1: Environment preparation.

[0026] Laser interferometers have stringent requirements for the measurement environment; environmental factors such as temperature, humidity, and vibration significantly affect measurement accuracy. Temperature changes cause alterations in the laser wavelength, thus affecting the measurement results. For example, for every 1°C increase in temperature, the laser wavelength changes, causing deviations in the measurement results.

[0027] Therefore, it is necessary to ensure that the ambient temperature is stable before calibration, generally within the range of 20℃±2℃, and temperature fluctuations should be minimized during the calibration process. An air conditioning system or constant temperature equipment can be used to maintain a stable ambient temperature, and the laser interferometer and the device under test should be placed in a temperature-stable environment for a sufficient period of time to allow them to reach thermal equilibrium.

[0028] Ambient humidity also affects the performance of laser interferometers. High humidity can cause moisture to adhere to the surface of optical components, affecting laser propagation and reflection. Therefore, the ambient humidity should be maintained within the range of 40%-60%, which can be controlled through dehumidification equipment or ventilation systems.

[0029] Vibration can also interfere with the calibration process. External vibrations may cause minute displacements or vibrations in the optical components of the laser interferometer, leading to unstable interference fringes and affecting measurement accuracy. To avoid interference from external vibrations, the laser interferometer should be placed on a vibration isolation platform. This platform effectively reduces the impact of vibrations from ground vibrations, equipment operation, and other sources. When placing the vibration isolation platform, ensure it is level and maintain a certain distance from surrounding equipment to minimize interference from vibration sources.

[0030] Step S2: Cleaning optical components.

[0031] The cleanliness of optical components such as laser emitters, receivers, and reflectors directly affects laser propagation and reflection, thus impacting measurement accuracy. Dust and stains can scatter the laser, affecting laser intensity and the accuracy of the measurement signal.

[0032] Therefore, gently wipe the optical windows of the laser emitter and receiver using tools such as anhydrous ethanol and lens paper. Be careful not to use excessive force to avoid damaging the optical components. Similarly, carefully clean the surface of the reflector with anhydrous ethanol and lens paper. The angular accuracy and surface quality of the reflector have a significant impact on the measurement results. If the reflector surface is not clean or the angular deviation is too large, the reflected laser light will deviate from the receiver, making it impossible to accurately measure the displacement.

[0033] Step S3: Laser wavelength calibration.

[0034] Using known length etalons as references, these etalons are rigorously calibrated, and their length values ​​are traceable to national standards. For example, high-precision gauge blocks can achieve dimensional accuracy down to the nanometer level. The laser interferometer is activated, allowing the laser to pass through the reference etalons, and the number of interference fringes at that standard length is measured. According to the principle of laser interference, there is a definite relationship between the laser wavelength and the number of interference fringes. By measuring multiple standard lengths, multiple sets of data are obtained, and the actual wavelength of the laser is calculated using a data processing algorithm. If the measured laser wavelength deviates from the theoretical value, the laser wavelength can be adjusted using the adjustment device of the laser interferometer to bring it closer to the theoretical value.

[0035] Step S4: Straightness calibration.

[0036] Mount the device under test (DUT) on a linear guide rail and fix the reflector of the laser interferometer to the end of the DUT. Adjust the position of the laser emitter so that the laser beam is parallel to the linear guide rail of the DUT. Then, move the DUT so that the reflector reciprocates along the linear guide rail.

[0037] During the movement of the device under test (DUT), a laser interferometer collects interference fringe data and converts it into displacement data. Analysis of this displacement data reveals the straightness error of the linear guide rail. If the straightness error exceeds the allowable range, it can be reduced by adjusting the installation position or mechanical structure of the DUT. For example, fine-tuning the height of the DUT's support points or adjusting the guide rail's fixing bolts can alter the device's orientation, thereby reducing the straightness error.

[0038] Step S5: Abbe error calculation.

[0039] The formula for calculating Abbe error is: ; in, Indicates Abbe error; This indicates the offset distance between the installation height of the measuring optical lens assembly and the motion axis of the device under test; It represents the angular motion error (such as pitch, yaw, etc.) generated by the tested equipment during the movement.

[0040] For example, in the inspection of a certain machine tool, the offset distance of the optical lens group is measured. =50mm, angular motion error generated by the machine tool during movement. =0.001 radians, then the Abbe error is calculated according to the formula. .

[0041] After calculating the Abbe error, the measurement results are corrected or the equipment installation is adjusted according to the actual situation to reduce the impact of the Abbe error on the measurement accuracy.

[0042] Step S6: Calculate the cosine error.

[0043] The principle of cosine error calculation is based on the difference between the measured distance and the actual movement distance when the laser beam path is not collimated with the measured axis. Let the angle between the laser beam and the measured axis be θ. The actual distance traveled was The measured distance is The approximate calculation formula is: ; Therefore, the cosine error is: ; This formula is applicable In smaller cases, when When smaller, ,at this time .

[0044] For example, in the determination of positioning error of a coordinate measuring machine, the angle between the laser beam and the direction of slide movement is... =0.01 radians, actual distance traveled =100mm, then according to the approximate formula .

[0045] By calculating the cosine error, the measurement results can be corrected, thereby improving the accuracy of the measurement.

[0046] Step S7: Calculate dead travel error.

[0047] The dead-path error is caused by the optical path difference (i.e., dead path) between the two coherent beams of the laser interferometer at the zero position during linear measurement. After the measurement system is calibrated, changes in environmental conditions (such as temperature and air pressure) will cause changes in the laser wavelength, and the dead-path part will not be compensated.

[0048] Considering changes in environmental factors, the dead distance length is assumed to be... The wavelength of a laser in a vacuum is The actual wavelength under the influence of environmental factors is The dead-path error is: ; For example, dead length =10mm, wavelength in vacuum =632.8nm, the actual wavelength changes due to changes in ambient temperature. =632.9nm, then the dead path error .

[0049] By calculating the dead travel error, it can be compensated for during the measurement process, thereby improving measurement accuracy.

[0050] Example 1 This embodiment takes the X-axis displacement measurement and calibration of a certain type of high-precision CNC machine tool as an example to demonstrate the specific implementation process and effect of the calibration method of the present invention.

[0051] A laser interferometer of brand A was used, with a nominal measurement accuracy of ±0.5ppm, equipped with a linear measuring mirror group. The device under test was a high-precision CNC machine tool with an X-axis travel of 1000mm. High-precision gauge blocks were selected as length standards, with a length accuracy of ±0.001mm, for laser wavelength calibration. In addition, auxiliary tools such as a thermometer / hygrometer, a vibration isolation platform, anhydrous ethanol, and lens paper were prepared.

[0052] Step S1, Environmental Preparation: Place the laser interferometer and CNC machine tool in a temperature- and humidity-controlled workshop. Use an air conditioning system to control the ambient temperature at 20℃±1℃ and the humidity at 50%±5%. Install the laser interferometer on a vibration isolation platform, ensuring it is placed horizontally and at least 1 meter away from surrounding equipment to reduce vibration and other interference.

[0053] Step S2, Optical Component Cleaning: Using lens paper soaked in anhydrous ethanol, gently wipe the optical surfaces of the laser emitter, receiver, and reflector of the laser interferometer to remove dust and stains. During the cleaning process, take care to avoid scratching the optical component surfaces to ensure cleanliness and reflective performance.

[0054] Step S3, Laser Wavelength Calibration: Place a 100mm long gauge block on the measurement path of the laser interferometer, start the laser interferometer, and allow the laser beam to pass through the gauge block. Measure the number of interference fringes produced by the laser along the length of the gauge block. Repeat the measurement 5 times and record the number of interference fringes each time.

[0055] Based on the principle of laser interference, the actual wavelength of the laser was calculated. The calculation revealed a deviation of 0.002 nm between the actual and theoretical wavelengths. The wavelength was then adjusted using the wavelength adjustment device of the laser interferometer to bring it closer to the theoretical value.

[0056] Step S4, Straightness Calibration: Fix the reflector of the laser interferometer onto the X-axis worktable of the CNC machine tool, and adjust the position of the laser emitter so that the laser beam is parallel to the X-axis guide rail. Set the X-axis of the CNC machine tool to perform reciprocating linear motion at a speed of 50 mm / min, with a motion range of 0-1000 mm. The laser interferometer collects interference fringe data in real time and converts it into displacement data, recording the displacement data every 1 mm of movement.

[0057] Step S5, Abbe error calculation and compensation: Measure the installation height of the measuring optical lens group and the offset distance between the X-axis motion axis. =30mm, the angular motion error generated by the machine tool during movement is measured by the machine tool's angle sensor. =0.0008 radians.

[0058] According to the Abbe error calculation formula The Abbe error was calculated. During the measurement data processing, Abbe error compensation is performed by subtracting the Abbe error value from the measured displacement data to obtain a more accurate displacement measurement result.

[0059] Step S6, Cosine Error Calculation and Compensation: Determine the angle between the laser beam and the X-axis through measurement and analysis. =0.005 radians, the actual movement distance in this measurement is taken as... =500mm.

[0060] According to the formula for calculating cosine error The cosine error was calculated. Similarly, during data processing, cosine errors are compensated to correct the displacement data obtained from the measurements.

[0061] Step S7, Dead Stroke Error Calculation and Compensation: Given the dead stroke length =8mm, wavelength in vacuum =632.8nm, the actual wavelength changed due to changes in ambient temperature and air pressure during the measurement process. =632.85nm.

[0062] According to the formula for calculating dead travel error The dead travel error was calculated. Dead-travel errors are compensated for in the measurement data to improve measurement accuracy.

[0063] During the straightness calibration process, displacement measurement data of the X-axis at different positions were recorded, as shown in Table 1.

[0064] Table 1. Linear displacement measurement data of the X-axis at different positions.

[0065] The data shows that there was a large error in the displacement measurement before calibration. After calculating and compensating for Abbe error, cosine error, dead path error, etc., the measured displacement after calibration is closer to the true value, and the error is significantly reduced.

[0066] Before calibration, the X-axis was repeatedly measured multiple times, and the standard deviation of the measurement results was [value missing]. =0.035mm, with a maximum error of 0.12mm. After calibration, the same number of repeated measurements were performed, and the standard deviation of the measurement results decreased to =0.002mm, the maximum error is reduced to 0.01mm. The comparison clearly shows that the calibration method of this invention effectively improves the measurement accuracy of the laser interferometer, resulting in more stable and accurate measurement results, meeting the stringent requirements of high-precision CNC machine tools for displacement measurement accuracy.

[0067] Example 2 This embodiment takes the surface profile measurement and calibration of an aero-engine blade as an example to further verify the universality and effectiveness of the calibration method. This application scenario has extremely high requirements for measurement accuracy and environmental adaptability, and the shape of the measurement object is complex, which is different from the linear displacement measurement in Embodiment 1.

[0068] A high-resolution and stable laser interferometer of brand B was selected, with a measurement accuracy of ±0.3ppm, and equipped with an optical lens group suitable for measuring complex curved surfaces. The object under test was an aero-engine blade, and a high-precision standard template was used as a reference. The profile accuracy of this template had been rigorously calibrated. A high-precision three-dimensional adjustment platform was prepared to fix the blade and the optical components of the laser interferometer, as well as environmental monitoring equipment (thermometer, hygrometer, barometer, etc.).

[0069] Step S1, Environmental Preparation: Measurements were conducted in an aero-engine manufacturing workshop with strict environmental control. A constant temperature and humidity system was used to maintain the temperature at 20℃±0.5℃ and the humidity at 45%±3%. A high-precision air pressure regulator was used to stabilize the air pressure near standard atmospheric pressure. The laser interferometer and blades were placed on a high-precision vibration isolation platform with active vibration isolation capabilities, effectively isolating vibrations generated by other equipment operating within the workshop.

[0070] Step S2, Optical Component Cleaning: Using professional optical cleaning tools, including ultra-clean lens paper and high-purity anhydrous ethanol, carefully clean the laser emitter and receiver of the laser interferometer, as well as the special optical mirror used for measuring blade profiles. The cleaning process follows strict operating procedures to ensure that the surfaces of the optical components are free of any dust, oil, and impurities, avoiding interference with laser propagation and interference fringes.

[0071] Step S3, Laser Wavelength Calibration: Place the standard template on the three-dimensional adjustment platform and adjust its position and angle so that the laser beam can accurately scan the standard contour of the template. Start the laser interferometer and perform multiple scan measurements on the template, recording the interference fringe data generated during each scan.

[0072] Based on the principle of laser interferometry and the known dimensions of a standard template, the actual wavelength of the laser is calculated using a complex data processing algorithm. After calculation and comparison, if a deviation is found between the laser wavelength and the theoretical value, fine-tuning is performed using the high-precision wavelength adjustment system built into the laser interferometer to achieve the optimal measurement state for the laser wavelength.

[0073] Step S4, Blade Profile Measurement and Calibration: Fix the aero-engine blade on a three-dimensional adjustment platform. Adjust the position and attitude of the blade precisely by adjusting the platform so that the measurement beam of the laser interferometer can scan and measure along the profile of the blade.

[0074] During the measurement process, the laser interferometer acquires interference fringe data in real time and converts it into three-dimensional coordinate data of the blade profile. Due to the complexity of the blade profile, various installation errors will occur during the measurement process, such as Abbe error, cosine error, and local measurement errors caused by the micro-morphology of the blade surface.

[0075] Step S5, Abbe error calculation and compensation: Measure the perpendicular distance between the optical mirror group and the measurement point on the blade profile using a precise laser interferometer. And using high-precision angle measurement equipment to monitor minute angle changes of the blades during the scanning process. According to Abbe's error formula Calculate the Abbe error.

[0076] For example, at a certain measurement point, the measurement is obtained. =25mm, =0.001 radians, then the Abbe error During data processing, Abbe error compensation is performed on the measurement data of each measurement point to correct measurement deviations caused by Abbe error.

[0077] Step S6, Cosine Error Calculation and Compensation: Using a precise beam collimation measurement device, measure the angle between the laser beam and the blade profile measurement direction. According to the cosine error formula Calculate the cosine error.

[0078] Assuming that in a certain measurement segment, the actual measured length =50mm, the included angle was measured. =0.006 radians, then the cosine error Cosine error compensation is applied to the measurement data at each measurement point to improve measurement accuracy.

[0079] Step S7: Handling local measurement errors related to the micro-morphology of the blade surface: Due to the presence of micro-processing textures and roughness on the surface of aero-engine blades, local interference will occur in laser interferometry, leading to measurement errors.

[0080] By employing multiple measurements and averaging the results, combined with advanced filtering algorithms, the measurement data is processed to remove outlier data points caused by microscopic morphology, smooth the measurement curves, and improve the reliability of the measurement data.

[0081] 1. Data recording and analysis.

[0082] During the blade profile measurement process, the original measurement coordinate data and the coordinate data after error compensation are recorded for each measurement point. A detailed analysis of the measurement data is performed, including plotting the blade profile contour curve, comparing the contour curves before and after calibration with the contour curve of the standard template, and calculating the contour deviation. Simultaneously, the error distribution at different locations is analyzed to determine the effectiveness of the calibration method in correcting measurement errors at different locations.

[0083] Data analysis revealed that in areas with significant curvature changes, such as the leading and trailing edges of the blade, the maximum deviation between the measured profile and the standard profile before calibration reached 0.15 mm, while the maximum deviation decreased to 0.02 mm after calibration. In the flat area in the middle of the blade, the standard deviation of the measurement deviation was 0.08 mm before calibration, while the standard deviation decreased to 0.005 mm after calibration.

[0084] 2. Verification of calibration effectiveness.

[0085] The same blade was measured using another coordinate measuring machine C, which had been calibrated with higher precision, and the measurement results were used as a reference standard. The measurement results before and after calibration of this laser interferometer were compared with the reference standard to verify the effectiveness of the calibration method.

[0086] The results show that the consistency between the blade profile measured by the laser interferometer and the reference standard is significantly improved after calibration. All measurement indicators meet the high precision requirements of aero-engine blade manufacturing, proving that the calibration method of the present invention also has good versatility and effectiveness in complex curved surface measurement scenarios, and can effectively improve the measurement accuracy of the laser interferometer in complex application environments.

[0087] Therefore, this invention employs the aforementioned calibration method for installation errors of laser interferometers. In terms of improving measurement accuracy, by comprehensively and systematically calibrating various errors generated during the installation process of the laser interferometer, such as Abbe error, cosine error, and dead-path error, the influence of these errors on the measurement results can be effectively eliminated or reduced, significantly improving the measurement accuracy of the laser interferometer. Compared with traditional calibration methods, it can more accurately measure physical quantities such as displacement, length, and angle of objects, meeting the high-precision measurement needs of fields such as industrial manufacturing, aerospace, and scientific research experiments.

[0088] In terms of reducing calibration costs, this invention avoids reliance on expensive physical gauge blocks and complex specialized equipment. Through reasonable environmental control, cleaning of optical components, error calculation based on the principle of optical wave interference, and calibration strategies, it reduces equipment and labor costs during the calibration process. Simultaneously, by improving measurement accuracy, it reduces product rework and scrap caused by measurement errors, indirectly lowering production costs.

[0089] In terms of simplifying the operation process, this invention provides clear and specific calibration steps and calculation methods. Operators only need to follow the steps of environmental preparation, optical component cleaning, laser wavelength calibration, and straightness calibration, and use the corresponding calculation formulas to calculate and adjust the error. No complicated professional skills and experience are required, which reduces the difficulty of operation and improves the calibration efficiency.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A calibration method for installation error of a laser interferometer, characterized in that, Includes the following steps: Step S1, Environmental Preparation: Set the temperature, humidity, and vibration parameters of the laser interferometer calibration environment; Step S2, cleaning optical components: Wipe the optical components, including the laser emitter, receiver and reflector, with anhydrous ethanol and lens paper; Step S3: Laser wavelength calibration; Step S4: Straightness calibration; Step S5: Abbe error calculation; Step S6: Calculate the cosine error; Step S7: Calculate dead travel error.

2. The calibration method for installation error of a laser interferometer according to claim 1, characterized in that, In step S1, the temperature is controlled within the range of 20℃±2℃; the ambient humidity is maintained within the range of 40%-60%. Use vibration isolation platforms to reduce the impact of ground vibration and vibration generated by equipment operation; when placing vibration isolation platforms, ensure that they are level and keep a distance from surrounding equipment to reduce interference from vibration sources.

3. The calibration method for installation error of a laser interferometer according to claim 1, characterized in that, In step S3, a known length etalon is used as a reference, the laser interferometer is started, and the laser is allowed to pass through the reference etalon to measure the number of interference fringes of the laser at the standard length. Based on the principle of laser interference, multiple sets of data are obtained by measuring multiple standard lengths, and the actual wavelength of the laser is calculated using a data processing algorithm. When the measured laser wavelength deviates from the theoretical value, the laser wavelength is adjusted using the adjustment device of the laser interferometer.

4. The calibration method for installation error of a laser interferometer according to claim 1, characterized in that, In step S4, the device under test is mounted on a linear guide rail, and the reflector of the laser interferometer is fixed at the end of the device under test; the position of the laser emitter is adjusted so that the laser beam is parallel to the linear guide rail of the device under test; then, the device under test is moved so that the reflector reciprocates along the linear guide rail. During the movement of the device under test, the laser interferometer collects interference fringe data and converts it into displacement data; by analyzing the displacement data, the straightness error of the linear guide rail of the device under test is obtained. When the straightness error exceeds the allowable range, the error can be reduced by adjusting the installation position or mechanical structure of the equipment under test.

5. The calibration method for installation error of a laser interferometer according to claim 1, characterized in that, In step S5, the Abbe error is calculated using the following formula: ； in, Indicates Abbe error; This indicates the offset distance between the installation height of the measuring optical lens assembly and the motion axis of the device under test; This indicates the angular motion error generated by the tested device during its movement.

6. The calibration method for installation error of a laser interferometer according to claim 1, characterized in that, In step S6, the cosine error calculation principle is based on the difference between the measured distance and the actual movement distance when the laser beam path is not collimated with the measured axis. Let the angle between the laser beam and the axis being measured be . The actual distance traveled was The measured distance is The approximate calculation formula is: ； Therefore, the cosine error is: ； in, This represents the cosine error.

7. The calibration method for installation error of a laser interferometer according to claim 1, characterized in that, In step S7, the dead path error is caused by the optical path difference between the two coherent lights of the laser interferometer at the zero position during the linear measurement process, i.e., the dead path. After the measurement system is calibrated, changes in environmental conditions will cause changes in the laser wavelength, and the dead path part will not be compensated. Let the dead process length be The wavelength of a laser in a vacuum is The actual wavelength under the influence of environmental factors is The dead-path error is: ； in, This indicates the dead-path error.

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