Journals >Optics and Precision Engineering
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2022
Volume: 30 Issue 13
11 Article(s)
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Information Sciences
Detection of foreign object debris on night airport runway fusion with self-attentional feature embedding
Zifen HE, Guangchen CHEN, Sen WANG, Yinhui ZHANG, and Linwei GUO
Foreign object debris （FOD） on an airport runway threaten aircraft safety during takeoff and landing， especially at night. This study introduces an intelligent vision algorithm to detect debris on airport runways at night. Considering the problems of existing models such as low detection accuracy owing to a tendency toForeign object debris （FOD） on an airport runway threaten aircraft safety during takeoff and landing， especially at night. This study introduces an intelligent vision algorithm to detect debris on airport runways at night. Considering the problems of existing models such as low detection accuracy owing to a tendency to focus on local features， a CSPTNet debris detection algorithm fused with self-attentional feature embedding is proposed. This algorithm replaces the standard BottleNeck module prevalent in conventional models with a Transformer BottleNeck module. In addition， the feature patch is flat segmented and embedded with position feature encoding to transform image representation from the pixel format to vector format. After capturing the relationship between the pixels in a high-dimensional vector space， the multi-head self-attention mechanism is employed to achieve the fusion of global and local features by obtaining feature information aggregated by different branches from the attention branch subspace. To solve the problems of blurred contour edges and difficult positioning due to the small scale of objects in datasets， we introduce the CIoU loss function to optimize predicted frame sizes and center positions. Thereby， the positioning accuracy of foreign object contours is enhanced. The experimental results show that the detection speed of this algorithm reaches 38 frames/s， which meets the requirements of real-time detection， and its average accuracy is 88.1%. Compared with the experimental results of the standard bottleneck module， the accuracy is increased by 5.7% through the Transformer BottleNeck module fusion with self-attentional feature embedding. In addition， compared with the state-of-the-art model YOLOv5， our is 5.2% more accurate. The obtained results demonstrate the effectiveness and engineering practicability of CSPTNet for FOD detection on airport runways at night..
Optics and Precision Engineering
- Publication Date: Jul. 10, 2022
- Vol. 30, Issue 13, 1591 (2022)
Hyperspectral reconstruction from RGB images based on Res2-Unet deep learning network
Beibei SONG, Suina MA, Fan HE, and Wenfang SUN
Because of hyperspectral imaging equipment are expensive， a deep learning network to reconstruct high-quality hyperspectral images from easily obtained RGB images was proposed. The proposed network was based on the Unet framework， and its backbone network was primarily constructed using the Res2Net module， which could Because of hyperspectral imaging equipment are expensive， a deep learning network to reconstruct high-quality hyperspectral images from easily obtained RGB images was proposed. The proposed network was based on the Unet framework， and its backbone network was primarily constructed using the Res2Net module， which could extract fine local and global image features. The channel attention mechanism was introduced to adaptively adjust the channel characteristic response， and the information of different scales and depths was fully integrated through a skip connection between the coding and decoding paths. Finally， it was trained and tested on the dataset provided by the new trends in the image restoration and enhancement （NTIRE） 2020 international challenge. Experiments show that compared with the adaptive weighted attention network （AWAN） and hierarchical regression network （HRNet）， the proposed method obtains the best results in the four objective evaluation methods， such as the mean of relative absolute error （MRAE）， root mean square error （RMSE）， peak signal-to-noise ratio （PSNR）， and mean of spectral angle mapper （MSAM）. Compared with AWAN and HRNet， the proposed method improves the mean of the PSNR by 0.08 dB and 1.73 dB， respectively， on the clean track， and 0.72 dB and 0.97 dB， respectively， on the real-world track. The proposed method reconstructs images with better subjective quality in the low-frequency flat area and the high-frequency texture area than the hyperspectral reference images..
Optics and Precision Engineering
- Publication Date: Jul. 10, 2022
- Vol. 30, Issue 13, 1606 (2022)
Relocation non-maximum suppression algorithm
Shuzhi SU, Runbin CHEN, Yanmin ZHU, and Bowen JIANG
Non-Maximum Suppression （NMS） is a post-processing algorithm used for object detection. It selects optimal bounding boxes from the bounding boxes set and suppresses other bounding boxes. NMS selects the bounding box with the highest score of classification confidence as the optimal bounding box. However， it ignores theNon-Maximum Suppression （NMS） is a post-processing algorithm used for object detection. It selects optimal bounding boxes from the bounding boxes set and suppresses other bounding boxes. NMS selects the bounding box with the highest score of classification confidence as the optimal bounding box. However， it ignores the correlation between localization accuracy and the classification confidence score. The classification confidence score cannot effectively represent the localization accuracy. This paper proposes a novel Relocation Non-Maximum Suppression （R-NMS） algorithm to solve the above-mentioned problem. First， the bounding box with the highest score of classification confidence in the bounding boxes set is selected as the optimal bounding box. Second， a new box distance measurement method is proposed based on R-NMS instead of using Intersection over Union （IoU） to measure the distance between the bounding boxes. Then， the location information of the bounding boxes around the optimal bounding box is obtained. Finally， the location information is used to relocate the optimal bounding box to obtain the new optimal bounding box. Compared with NMS and Soft-NMS， the mAP of R-NMS on YOLOv3 increased by 0.7 % and 0.5 %， respectively. The mAP of R-NMS on Faster-RCNN is 80.83 %， and the effectiveness of the proposed algorithm in the improvement of the mAP of various object detectors is confirmed..
Optics and Precision Engineering
- Publication Date: Jul. 10, 2022
- Vol. 30, Issue 13, 1620 (2022)
Defect detection in ceramic substrate based on improved YOLOV4
Feng GUO, Qibing ZHU, Min HUANG, and Xiaoxiang XU
A ceramic substrate is an important basic material for semiconductor components. Detecting defects in it is of great significance for ensuring high product quality. An automatic defect detection method for a ceramic substrate based on the improved YOLOV4 network was proposed in this paper. To ease the difficulty associA ceramic substrate is an important basic material for semiconductor components. Detecting defects in it is of great significance for ensuring high product quality. An automatic defect detection method for a ceramic substrate based on the improved YOLOV4 network was proposed in this paper. To ease the difficulty associated with defect detection caused by small defect size， varying color and shape， and large size variation between different kinds of defects in a ceramic substrate， the improved YOLOV4 model optimized the design of the initial prior box by referring to the Complete Intersection over Union （CIoU） idea. The model then introduced the Confidence Loss function based on the Gradient Harmonizing Mechanism （GHM） and CRISS-Cross Attention Net （CCNet） to improve the defect detection ability. The experimental results show that the average accuracy of the detection method based on the improved YOLOV4 model for ceramic substrate defects， including stain， foreign matter， gold edge bulge， ceramic gap and damage， can reach 98.3%. This accuracy meets the industry requirements for the detection accuracy of ceramic substrate defects..
Optics and Precision Engineering
- Publication Date: Jul. 10, 2022
- Vol. 30, Issue 13, 1631 (2022)
Micro/Nano Technology and Fine Mechanics
Influence of micropore airflow pressurization on flatness of laser etched ITO glass
Rong CHEN, Zhaojie CHEN, and Jin XIE
During laser etching of indium tin oxide （ITO） glass， micro-deformation of the glass workpiece， which results from positioning problems， causes breakpoints or deformation of micro-scale etching lines， resulting in short circuits and open circuits in adjacent areas. Therefore， during the laser etching of ITO glass surfaDuring laser etching of indium tin oxide （ITO） glass， micro-deformation of the glass workpiece， which results from positioning problems， causes breakpoints or deformation of micro-scale etching lines， resulting in short circuits and open circuits in adjacent areas. Therefore， during the laser etching of ITO glass surface lines， microporous ceramics are typically used to pressurize the workpiece with airflow from a micro-hole array to ensure high-precision laser etching. In this study， the micropore airflow pressure distribution under different processing techniques was analyzed， and the influence of the gas flow pressure and the etching gap on the flatness of the etched surface of the ITO glass was explored. The results revealed that after being pressurized by the microporous airflow， the workpiece is subjected to a positive pressure in the area where the gas flows so that the pressure distribution in the processing area is relatively uniform. Such a uniform air pressure on the surface of the workpiece can prove beneficial for the positioning of the etched surface； however， an excessive pressure may lead to micro-deformation of the workpiece. The experimental results indicate that the flatness can be as low as 8 μm under an appropriate pressure， and at a pressure of 0.16-0.2 kPa and an etching gap of 1.8-1.9 mm， the surface pressure of the workpiece becomes 13.2-14.4 Pa. At this time， the surface degree is the best， and the etched lines on the micron scale are clear and do not cause damage. Finally， the laser etching process of an ITO glass pressurized using a micro-hole airflow was conducted， and surface fine lines of 8 μm and 25 μm could be etched. This resolved the issues of short circuits or open circuits in the product， which are typically caused by local breakpoints or deformations resulting from the etching process， which is usually conducted in the presence of air without micropores..
Optics and Precision Engineering
- Publication Date: Jul. 10, 2022
- Vol. 30, Issue 13, 1564 (2022)
Theoretical modeling and displacement response characteristics of V-shaped electrothermal actuator
Feng LI, Xinjie WANG, and Hao CHEN
To study the characteristics of displacement response for a V-shaped electrothermal actuator， considering that the material parameters are affected by temperature nonlinearity and discontinuous boundary problems in the mathematical model， the characteristics of displacement response for the V-shaped electrothermal actuTo study the characteristics of displacement response for a V-shaped electrothermal actuator， considering that the material parameters are affected by temperature nonlinearity and discontinuous boundary problems in the mathematical model， the characteristics of displacement response for the V-shaped electrothermal actuator were studied in theory， simulation， and experiment. First， an electro-thermal-mechanical coupling model of a V-shaped electrothermal actuator was established by introducing updating functions of a material parameter related to the temperature. Expressions for the temperature and transient displacement of the V-shaped electrothermal actuator were obtained using the improved Chebyshev spectrum method to solve the constructed coupling model. Then， a finite element simulation and theoretical analysis of the temperature and displacement of the V-shaped electrothermal actuator were performed to verify the correctness of the model. Finally， an experimental platform for the transient displacement response of the electrothermal actuator was constructed. The experimental results of the displacement response for the V-shaped electrothermal actuator under constant voltage excitation were compared with the theoretical and simulation results. The displacement response of the V-shaped electrothermal actuator under a periodic square wave voltage was tested. The test results reveal the following： the V-shaped electrothermal actuator performs periodic variation after a certain amount of time. The cycle is identical to that of the square wave voltage. Under similar conditions of other parameters， the average displacements of the electrothermal driver under the action of the peak-to-peak 14 V periodic square wave voltage are 20 µm. Furthermore， the average displacements under the action of the peak-to-peak 7 V periodic square wave voltage are 28 µm. The displacement variation of the electrothermal actuator under the action of a periodic square wave voltage with a frequency of 50 Hz is 7 µm larger than that under a frequency of 100 Hz. The mean displacement is approximately equal. However， the variation range of displacement is negatively correlated with frequency..
Optics and Precision Engineering
- Publication Date: Jul. 10, 2022
- Vol. 30, Issue 13, 1572 (2022)
Optimization of sensitivity of MEMS micro-pressure sensor
Shiqiu PENG, and Saining ZHU
Aiming to increase the sensitivity of a micro-electro-mechanical system （MEMS） micro-pressure sensor， the primary factors that influence sensor sensitivity were introduced according to the working principle of a silicon piezoresistive pressure sensor. Subsequently， simulations were conducted using the COMSOL MultiphysiAiming to increase the sensitivity of a micro-electro-mechanical system （MEMS） micro-pressure sensor， the primary factors that influence sensor sensitivity were introduced according to the working principle of a silicon piezoresistive pressure sensor. Subsequently， simulations were conducted using the COMSOL Multiphysics software to analyze the influence of film thickness， optimal position， and length of the varistor. Based on the simulation results， the sensitivity of a 40 kPa MEMS micro-pressure sensor was optimized. The sensitivity of the micro-pressure sensor could be enhanced effectively by reducing the film thickness to 15 μm， setting the length of the varistor to 120 μm， and strategically placing the varistor 10 μm away from the edge of the film. The test results of the optimized sensor show that by optimizing the structure design， a sensitivity of 0.444 mV/kPa can be achieved for the MEMS micro-pressure sensor. The sensitivity of the optimized sensor is 26.8% greater than that of the standard sensor， which has a sensitivity of 0.35 mV/kPa. Thus， the system requirements of higher sensitivity and linearity can be satisfied using the optimized MEMS micro-pressure sensor..
Optics and Precision Engineering
- Publication Date: Jul. 10, 2022
- Vol. 30, Issue 13, 1582 (2022)
Modern Applied Optics
Interferometric coherence imaging aberration due to non-rotationally symmetric secondary wavefront degradation
Sida LÜ, Mingzhuo LI, Haixiang HU, Donglin XU, and Xuejun ZHANG
The degradation of the detected wavefront during the propagation of the compensation optical path in the interferometric compensation detection system inevitably introduces interferometric coherent imaging aberration， causing the instrument transfer function to degrade sharply in the high frequency band and severely liThe degradation of the detected wavefront during the propagation of the compensation optical path in the interferometric compensation detection system inevitably introduces interferometric coherent imaging aberration， causing the instrument transfer function to degrade sharply in the high frequency band and severely limiting the detection accuracy of interferometric compensation detection. In this study， an interferometric coherence imaging aberration model is developed to reveal the degradation mechanism of wavefront spatial frequency information caused by interferometric coherence imaging aberration. First， a non-rotationally symmetric wavefront propagation theory is proposed to describe the evolution mechanism of the non-rotationally symmetric wavefront. Second， the mathematical model of interferometric coherent imaging aberration is established by combining the hybrid analysis method of fine beam tracing and wavefront evolution， and the numerical value of the FM function under the condition of non-rotationally symmetric secondary wavefront propagation is realized to further establish the function relationship between the out-of-focus amount and wavefront distribution. Finally， the experimental verification of the model is completed using the interference compensation detection system. The experimental results show that the residuals of the actual and expected values are less than 0.05 waves， the symmetric mean absolute percentage error （SMAPE） of the model is 8.26%， and the mean relative error （MRE） is 3.35%； therefore， the proposed model has a better fit than the theoretical one based on Talbot effect and Fresnel diffraction analysis proposed by the University of Arizona. The accuracy and predictability of the proposed model， which is important for improving the detection accuracy of interference compensation detection， are verified..
Optics and Precision Engineering
- Publication Date: Jul. 10, 2022
- Vol. 30, Issue 13, 1523 (2022)
Deep-space laser communications telescope array based on single photon detector
Xiaoliang LI, Rongke LIU, Jianjun WANG, and Xiangnan LIU
With the increase of different types of space borne detectors and data capacity， as well as the expansion of the exploration field， requirements in the deep space exploration of ground communication rate and communication distance are also increasing. Compared with radio communication， space laser communication has sevWith the increase of different types of space borne detectors and data capacity， as well as the expansion of the exploration field， requirements in the deep space exploration of ground communication rate and communication distance are also increasing. Compared with radio communication， space laser communication has several advantages， such as high data rate， narrow laser beam， higher security， terminal light-weight， and low power-consumption. Thus， it has great potential in deep space communication. However， space laser communication faces great challenges in the case of long distances. Generally， long-distance， high-sensitivity communication is performed by increasing the peak power of the transmit laser in the aircraft terminal， which increases the receiving area of the ground optical system， thereby improving the receiving sensitivity of the detector. By analyzing the number of photons reaching the surface of the detector， the PPM modulation system and superconducting nanowire single photon detector （SNSPD） is found to be significantly better for deep space laser communication. More specifically， the bit error rate （BER） of the system is derived from the detection probability and false probability of SNSPD. A receiving telescope array with an effective aperture of 10 m is composed of several telescopes through the combination of ‘or’ and ‘and’ signals. Subsequently， the BER of several different cascading modes is analyzed， and the results reveal that the BER with sixteen 2.5 m-aperture telescopes is relatively better than 10-7 under strong background conditions， a communication distance of 2.67 AU， and a communication rate of 1 Mb/s..
Optics and Precision Engineering
- Publication Date: Jul. 10, 2022
- Vol. 30, Issue 13, 1534 (2022)
Measurement of pixel full-well parameters of detector used on spaceborne spectrometer
Zhen CHANG, Yu WANG, Fang LIN, Xin ZHAO... and Fuqi SI|Show fewer author(s)
During the development of a charge-coupled device （CCD） imaging circuit， it is necessary to adjust the parameters of the CCD’s driving signal and repeatedly test the full-well parameters dozens or even hundreds of times to ensure the optimal full-well performance of the CCD. To achieve this， the general method employedDuring the development of a charge-coupled device （CCD） imaging circuit， it is necessary to adjust the parameters of the CCD’s driving signal and repeatedly test the full-well parameters dozens or even hundreds of times to ensure the optimal full-well performance of the CCD. To achieve this， the general method employed， known as the photon transfer curve method， requires integrating a sphere and other equipment to create a flat-field light source system. However， the resulting system is complex， and hence， it is unsuitable for application in a full-well testing method during the development of an imaging system. In this paper， a novel full-well testing method， a light-emitting diode （LED） point test method， is proposed. Accordingly， CCD full-well testing can be easily realized by developing an LED point light source and common civilian lens. The results reveal that the number of full-well electrons of a spaceborne CCD can reach 817.013ke-， and the error can be less than 0.643%. The results also indicate that the errors resulting from the LED point test method and the traditional method are， respectively， 0.0397% and 1.9% compared with the errors resulting from the photon transfer curve method. In summary， the LED point test method can be used as a general method to rapidly measure the full-well parameters of a CCD under simple conditions， and it can enhance the efficiency of CCD imaging circuit development..
Optics and Precision Engineering
- Publication Date: Jul. 10, 2022
- Vol. 30, Issue 13, 1542 (2022)
Controllable manipulation of long-distance microparticles based on fiber optic tweezers
Chunlei JIANG, Huasheng SHUI, Peng CHEN, Shuo FANG, and Tao WANG
The flexible manipulation of particles or cells in fluids， particularly the transport of cells or particles to a specified location， has proven to be of vital importance in cell analysis， disease diagnosis， drug delivery， etc. However， the flexibility of contact-free optical capture of cells or particles is clearly insThe flexible manipulation of particles or cells in fluids， particularly the transport of cells or particles to a specified location， has proven to be of vital importance in cell analysis， disease diagnosis， drug delivery， etc. However， the flexibility of contact-free optical capture of cells or particles is clearly insufficient owing to the short operating distance of optical fiber tweezers. Therefore， a novel optical fiber tweezer with a simple structure and controllable long-distance contact-free control of particles is proposed. In this study， a special cone-like flat port fiber probe is fabricated via heating and stretching techniques. A 980 nm laser passing through the fiber probe exerts a large scattering force on the particles， which gradually pushes the particles away from the fiber port. Simultaneously， with the aid of reverse fluid resistance， the output power of the laser light source is adjusted without moving the fiber probe. A polystyrene particle with a diameter of 6 µm in an axial position can be controlled round-trip with a distance of 102.2 µm. The intensity distribution of the optical tweezers is simulated using the finite element method， and the force exerted by the optical tweezers on the particles is analyzed using the Maxwell stress tensor method. The feasibility of the proposed cone-like flat port optical tweezers is verified via both experiments and simulations..
Optics and Precision Engineering
- Publication Date: Jul. 10, 2022
- Vol. 30, Issue 13, 1555 (2022)
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