Journals >Optics and Precision Engineering
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2024
Volume: 32 Issue 17
12 Article(s)
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Precision Measurement and Sensing
Grating interferometric precision nanometric measurement technology
Xinghui LI, and Can CUI
Grating interferometry is a crucial technology in precision nanometrology, valued for its high resolution, robustness, and adaptability for multi-axis measurement systems. It is essential in advanced semiconductor manufacturing and ultra-precision machine tools. This review first compares grating interferometry with laGrating interferometry is a crucial technology in precision nanometrology, valued for its high resolution, robustness, and adaptability for multi-axis measurement systems. It is essential in advanced semiconductor manufacturing and ultra-precision machine tools. This review first compares grating interferometry with laser interferometry and time grating, detailing their applications and performance. It then explains the two main principles: homodyne and heterodyne grating interferometry. The review also analyzes global development trends, highlighting key manufacturers and advancements in achieving nanometric to sub-nanometric precision in single and multi-axis systems. In addition, it examines error sources, classifications, and compensation methods in grating interferometry. Finally, it discusses the current state and future prospects of grating interferometers, offering insights for developing and optimizing measurement systems based on this technology..
Optics and Precision Engineering
- Publication Date: Sep. 10, 2024
- Vol. 32, Issue 17, 2591 (2024)
Displacement sensing mechanism and measurement model of planar two-dimensional time-grating based on alternating magnetic field
Ziran CHEN, hui OUYang, Hengxiao ZHANG, Kai PENG... and Nanchuan CUI|Show fewer author(s)
To address the limitations of traditional planar two-dimensional displacement sensors in ultra-precision lithography and large-area sensor manufacturing, a new method using a spatial alternating magnetic field is proposed. This method involves arranging uniform sine/cosine excitation windings on a fixed ruler and applyTo address the limitations of traditional planar two-dimensional displacement sensors in ultra-precision lithography and large-area sensor manufacturing, a new method using a spatial alternating magnetic field is proposed. This method involves arranging uniform sine/cosine excitation windings on a fixed ruler and applying time-quadrature electric current to these windings, creating a two-dimensional alternating magnetic field that links spatial displacement with a time reference. The method achieves spatial displacement measurement through a model of "dimension judgment + displacement decoupling." Dimension judgment is performed using the binary output signals from a dimension-judgment induction winding array. The alternating magnetic field is detected by a displacement-decoupling induction winding array arranged in two dimensions, producing spatial traveling-wave signals and enabling displacement decoupling via phase comparison. Error analysis of this two-dimensional time-grating displacement measurement model was conducted through electromagnetic simulation. A prototype and experimental platform were developed, demonstrating that within a 120 mm × 120 mm range, the maximum measurement errors were ±9.4 µm in the X direction and ±9.7 µm in the Y direction, with a resolution of 0.15 µm. This method achieves micron-level measurement accuracy using millimeter-sized excitation and induction windings, overcoming the limitations of traditional sensors in ultra-precision lithography and simplifying sensor manufacturing. The research holds significant theoretical and practical value..
Optics and Precision Engineering
- Publication Date: Sep. 10, 2024
- Vol. 32, Issue 17, 2612 (2024)
White-light interferometry immune to vibration disturbance over wide frequency region
Qian LIU, Le MI, and Xiaojin HUANG
The traditional white-light interferometer is highly sensitive to vibrations, causing scanning step errors and reducing measurement accuracy. To address this, a three-point arcsine (3P-Asin) algorithm is proposed. This method divides WLI interferograms into groups of three adjacent frames, with overlap between groups. The traditional white-light interferometer is highly sensitive to vibrations, causing scanning step errors and reducing measurement accuracy. To address this, a three-point arcsine (3P-Asin) algorithm is proposed. This method divides WLI interferograms into groups of three adjacent frames, with overlap between groups. By analyzing fringe movement, the phase shift deviation and exact scanning step are determined. Using this step, a least-squares method calculates phase and modulation for non-equal step scanning to reconstruct surface height. The 3P-Asin algorithm detects fast and large scanning step errors using only three interferograms, with no approximation. Simulations and experiments show it achieves an accuracy of 0.5% for a 10 μm step height and adapts to various surfaces in mechanical machining. Both theoretical and experimental results demonstrate that the 3P-Asin algorithm effectively attenuates scanning step errors across a wide frequency range, making it suitable for WLI in vibrating environments..
Optics and Precision Engineering
- Publication Date: Sep. 10, 2024
- Vol. 32, Issue 17, 2625 (2024)
Distributed stress measurement for water pressure test of diversion steel branch pipe
Guolu YIN, Jingming MA, Shengxian JIANG, Xin WANG... and Tao ZHU|Show fewer author(s)
The diversion steel branch pipe is large and complex to weld, requiring endurance for long-term water pressure of 6 MPa. There is a need for a high-precision, high-resolution stress measurement technique for comprehensive assessment during water pressure tests. Traditional strain gauges are limited to localized measureThe diversion steel branch pipe is large and complex to weld, requiring endurance for long-term water pressure of 6 MPa. There is a need for a high-precision, high-resolution stress measurement technique for comprehensive assessment during water pressure tests. Traditional strain gauges are limited to localized measurements and restricted by waterproofing, application processes, and temperature changes. This study proposes using optical frequency domain reflectometry for stress measurement in the pipe. A standard single-mode fiber sensor is laid along the weld seam for a spatial resolution of 5.8 cm. Stress correlates linearly with water pressure and varies periodically from 0.2 to 0.6 m along the weld seam. Maximum stress reaches 196.2 MPa at the crescent rib weld seam's waist, about 300 MPa at the main conical ring seam, and distributes symmetrically along the intersecting line, with a peak of 352.0 MPa near the waistline and minimal stress at the top and bottom..
Optics and Precision Engineering
- Publication Date: Sep. 10, 2024
- Vol. 32, Issue 17, 2635 (2024)
Single optical channel based Raman distributed optical fiber temperature measurement system
Yuxiang FENG, Zhikai LIU, Minnan HUANG, Yishan WANG, and Lidong LYU
To address the issue of position correction and temperature distortion caused by walk-off effects in conventional Raman distributed optical fiber temperature measurement systems, a new single optical channel scheme is proposed. This scheme incorporates a model for scattered light power correction and a temperature caliTo address the issue of position correction and temperature distortion caused by walk-off effects in conventional Raman distributed optical fiber temperature measurement systems, a new single optical channel scheme is proposed. This scheme incorporates a model for scattered light power correction and a temperature calibration algorithm to ensure accurate temperature measurement along the fiber. First, temperature demodulation formulas for single Raman Stokes and anti-Stokes light are derived based on the temperature sensitivity principle of Raman scattering. Since temperature demodulation via a single optical channel is hindered by the stability of pulse lasers and photodetectors, a temperature calibration unit and signal power correction algorithm are developed. An experimental platform was then built to compare the temperature measurement performance of traditional dual-channel systems with single channel Raman Stokes and Raman anti-Stokes schemes. Experiments on a 12 km fiber demonstrated that the scheme using Raman anti-Stokes light achieves a temperature deviation of -0.3 ℃ to 2.2 ℃, with a root mean square error of 1.0 ℃ and a spatial resolution of 6 m, showing superior performance over traditional systems. This single channel system with signal power correction offers high sensitivity and eliminates the walk-off correction issue inherent in dual-channel systems, proving its practical value..
Optics and Precision Engineering
- Publication Date: Sep. 10, 2024
- Vol. 32, Issue 17, 2645 (2024)
Perpendicularity measurement of multi-axis motion platform based on laser interferometry
Kaiyuan LUO, Wenwei ZHENG, and Lin YANG
Perpendicularity error is a critical geometric error in multi-axis motion platforms, indicating the vertical deviation of machine tool components during movement. This deviation significantly affects spatial positioning errors, particularly as the stroke length of the moving axis increases. Various methods exist for mePerpendicularity error is a critical geometric error in multi-axis motion platforms, indicating the vertical deviation of machine tool components during movement. This deviation significantly affects spatial positioning errors, particularly as the stroke length of the moving axis increases. Various methods exist for measuring perpendicularity error, including physical gauges, volumetric measurements, CCD measurements, planar gratings, laser trackers, and laser interferometry. However, these methods often suffer from drawbacks such as operational inconvenience, high costs, or inability to perform online measurements. This paper presents a multi-axis laser interferometric device for measuring perpendicularity, utilizing components like laser emitters, pentagonal beam splitters, prisms, straightness interferometers, and reflectors. With a well-designed optical path, this device can be integrated into the multi-axis motion platform, enabling efficient and precise online measurement of perpendicularity. A comparison test against a granite protractor showed a deviation of 1.4″ and a normalized deviation En<1, confirming the method's feasibility and accuracy..
Optics and Precision Engineering
- Publication Date: Sep. 10, 2024
- Vol. 32, Issue 17, 2654 (2024)
Whole-field deformation measurement of clear orthodontic aligner using electronic speckle pattern interferometry
Jiawen WANG, Junqing WU, Minyang WU, Yingbiao AN... and Fujun YANG|Show fewer author(s)
To objectively and accurately measure the full-field deformation of clear aligners for improved clinical effectiveness and safety, a comprehensive three-dimensional deformation measurement system based on laser electronic speckle pattern interferometry has been established. The specimen's surface is illuminated witTo objectively and accurately measure the full-field deformation of clear aligners for improved clinical effectiveness and safety, a comprehensive three-dimensional deformation measurement system based on laser electronic speckle pattern interferometry has been established. The specimen's surface is illuminated with a tri-wavelength laser, generating a color speckle pattern. A phase-shift device produces a quasi π/2 phase step for all three color channels. Multi-frame images of the color speckle pattern are captured using a 3CCD color camera. Deformation phases are extracted using a 90° step four-frame technique from the separated red, green, and blue channels. A window-deformable filter effectively denoises the phase fringe patterns, allowing six derivative components to be obtained directly from the three deformation components using a digital differential method. Results show that the system achieves a precision of no more than 2.4'' for micro-rotation and better than 10 με for strain measurements. Experimental results on clear aligners align closely with expected outcomes..
Optics and Precision Engineering
- Publication Date: Sep. 10, 2024
- Vol. 32, Issue 17, 2663 (2024)
Suppression of effects of air random disturbances in laser collimation measurements
Kuan DIAO, Xiaojun LIU, and Haiyu ZHAO
The highly directional laser collimated beam is extensively used as a linear measurement reference in precision measurement. However, random air disturbances like fluctuations in temperature, humidity, and atmospheric pressure can induce jitter, compromising stability and accuracy. This paper introduces a method to couThe highly directional laser collimated beam is extensively used as a linear measurement reference in precision measurement. However, random air disturbances like fluctuations in temperature, humidity, and atmospheric pressure can induce jitter, compromising stability and accuracy. This paper introduces a method to counteract these disturbances by using Empirical Mode Decomposition (EMD) combined with Least Squares (LS) fitting for laser collimation signal filtering. The developed signal processing scheme decomposes, reconstructs, and corrects laser signals to remove such interferences. Experiments under various disturbance conditions show that the method proposed results in a standard deviation of fluctuations of 0.01 μm in the horizontal direction and 0.02 μm in the vertical direction after processing the laser alignment signal following laser drift compensation, significantly improves the stability of laser collimation measurements affected by atmospheric randomness..
Optics and Precision Engineering
- Publication Date: Sep. 10, 2024
- Vol. 32, Issue 17, 2676 (2024)
Multi-pose coupled transformation calibration for combined tracking-based optical measurement
Renchuan YANG, Haihua CUI, Xifu ZHAO, Ronghui GUO, and Tao JIANG
Combining global positioning tracking with terminal measurement effectively addresses the overall measurement of large workpieces. The key to accuracy in this system is the transformation from the terminal to the target coordinate system. This paper introduces existing common feature points to calibrate the transit posCombining global positioning tracking with terminal measurement effectively addresses the overall measurement of large workpieces. The key to accuracy in this system is the transformation from the terminal to the target coordinate system. This paper introduces existing common feature points to calibrate the transit pose and addresses their station position constraints. To overcome these challenges, we propose a new multi-position coupled transit calibration method that eases global measurement system and feature point positioning requirements by using transit pose coupling with multiple targets to form equations for solutions. A multi-position coupled multi-point transit calibration method is also introduced to enhance pose solution stability and reduce calibration errors by coupling local feature points with the pose solution. Experiments comparing the methods demonstrate that the proposed multi-position and multi-point coupling transfer calibration method enhances stability and reduces the average measurement error by 10.13%, confirming its effectiveness..
Optics and Precision Engineering
- Publication Date: Sep. 10, 2024
- Vol. 32, Issue 17, 2686 (2024)
Coordinate unification and data fusion for composite measurement with contact and white light interferometric probes
Zhenying CHENG, Dongjian XU, Chengyao ZHANG, Yunlong LIU, and Ruijun LI
To achieve high-precision measurements of these components, micro/nano contact probes and white light interferometric probes must be combined for composite measurement. This paper presents a method to unify the spatial coordinate systems of the two probes using calibration points from a custom calibrator and the unit qTo achieve high-precision measurements of these components, micro/nano contact probes and white light interferometric probes must be combined for composite measurement. This paper presents a method to unify the spatial coordinate systems of the two probes using calibration points from a custom calibrator and the unit quaternion method to derive the spatial transformation matrix, evaluated by root mean square error (RMSE). A novel calibrator was designed to offer stable reference points, with a model linking their accuracy to coordinate unification precision. Additionally, a data fusion method blending spatial error ellipsoid search with weighted least squares was proposed, demonstrating a registration accuracy of 1.889 μm. This method decreased the relative error by 16% and improved repeatability precision by 38% compared to traditional least squares. The research enhanced the measurement precision and data fusion stability of composite measurement systems..
Optics and Precision Engineering
- Publication Date: Sep. 10, 2024
- Vol. 32, Issue 17, 2698 (2024)
Radio-frequency heterodyne detection of fiber-optic ultrasonic sensor
Wuxing LIUFU, Yizhi LIANG, Junjie CAO, Xiaoxuan ZHONG... and Long JIN|Show fewer author(s)
The detection sensitivity of fiber-optic ultrasound sensors is crucial for image quality in fiber-based photoacoustic imaging. In this study， we employed a dual-polarization fiber laser as the acoustic sensing element and introduced radio-frequency heterodyne demodulation for sensitivity enhancement. Experimental resulThe detection sensitivity of fiber-optic ultrasound sensors is crucial for image quality in fiber-based photoacoustic imaging. In this study， we employed a dual-polarization fiber laser as the acoustic sensing element and introduced radio-frequency heterodyne demodulation for sensitivity enhancement. Experimental results demonstrate that this method effectively eliminates noise from additional local radio-frequency oscillation sources. The proposed technique achieved an improved sensitivity， evidenced by a noise-equivalent pressure （NEP） of 9.0 Pa， compared to the 5.7 Pa offered by previous approaches within the frequency range of 8-32 MHz. Furthermore， applying this sensor to photoacoustic microscopy resulted in a signal-to-noise ratio enhancement of over 4 dB. The heterodyne detection technology significantly improves the sensitivity and image signal-to-noise ratio of fiber-optic sensors， facilitating the application of fiber-based photoacoustic imaging..
Optics and Precision Engineering
- Publication Date: Sep. 10, 2024
- Vol. 32, Issue 17, 2708 (2024)
Double-layer cross-type FBG tactile sensing unit based on strain sensitization
Shizheng SUN, Jiang HE, Hongyu QIN, Xiangyang XU, and Renxiang CHEN
Tactile perception is an important content of bionic intelligent perception， in order to improve the tactile sensitivity of fiber Bragg grating （FBG）， combined with the demand of tactile perception of the fingertip of the machine， this paper proposes a strain-enhanced FBG tactile perception unit. Firstly， based on the Tactile perception is an important content of bionic intelligent perception， in order to improve the tactile sensitivity of fiber Bragg grating （FBG）， combined with the demand of tactile perception of the fingertip of the machine， this paper proposes a strain-enhanced FBG tactile perception unit. Firstly， based on the analysis of strain sensitisation and tactile perception mechanism， a double-layer cross-type FBG tactile sensing unit based on strain sensitisation is designed， and a rigid spherical multi-point sensitisation structure is used for strain sensitisation； Then， the simulation analysis method was used to optimise the FBG spatial distribution and perform hydrostatic and thermodynamic simulations of the sensing unit. Finally， a haptic perception experiment platform was built， and temperature-force haptic synergistic perception experiments were completed in conjunction with a robotic hand. The simulation and experimental results show that the force haptic sensitivity of FBG1 and FBG2 are 18.069 nm/MPa and 1.065 nm/MPa， and the temperature sensitivity are 11.256 pm/°C and 11.153 pm/°C. The tactile sensing unit effectively improves tactile sensing sensitivity with good linearity and repeatability..
Optics and Precision Engineering
- Publication Date: Sep. 10, 2024
- Vol. 32, Issue 17, 2718 (2024)
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