A liquid crystal (LC) beam deflector with a microblazed grating produced by stepping photolithography and reactive ion etching (RIE) was reported. A homogeneously aligned nematic liquid crystal (NLC) materials are filled inside the microcavity of blazed grating, and sandwiched between two glass plates. An indium tin oxide (ITO) transparent electrode is deposited on it to provide the beam steering capability. Our LC-micro blazed grating device gives a high diffractive efficiency (about 95%) and a controllable large steering angle over 7.2° (for ne) and 1.7° (for no), respectively. It was found that this type of non-mechanical beam steering without any moving parts is ideally suited for applications in optical communication and optical interconnection network.
{"title":"Study on controllable LC-micro blazed grating beam deflector in free space","authors":"Junbo Yang, Suzhi Xu, Jingjing Zhang, Shengli Chang","doi":"10.1117/12.2181231","DOIUrl":"https://doi.org/10.1117/12.2181231","url":null,"abstract":"A liquid crystal (LC) beam deflector with a microblazed grating produced by stepping photolithography and reactive ion etching (RIE) was reported. A homogeneously aligned nematic liquid crystal (NLC) materials are filled inside the microcavity of blazed grating, and sandwiched between two glass plates. An indium tin oxide (ITO) transparent electrode is deposited on it to provide the beam steering capability. Our LC-micro blazed grating device gives a high diffractive efficiency (about 95%) and a controllable large steering angle over 7.2° (for ne) and 1.7° (for no), respectively. It was found that this type of non-mechanical beam steering without any moving parts is ideally suited for applications in optical communication and optical interconnection network.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"396 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122185207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The accuracy of the heterodyne laser interferometer is strongly restricted by the optical nonlinearity harmonics. In order to mathematically reveal the formation and transformation mechanism of optical nonlinearity harmonics, the behavior of the nonlinearity harmonics is investigated with an optical nonlinearity expression based on the optical mixing parameters in the measurement signal. It is found that the formation and transformation of the first-order and second-order nonlinearity harmonics are closely related to the orthogonality of the optical mixing parameters. When the optical mixing parameters satisfy the orthogonal relation, the optical nonlinearity is purely the second-order harmonic whose peak-to-peak value is at least one order smaller than that of the first-order harmonic in the same optical mixing degree, indicating that a larger optical mixing level does not necessarily lead to a considerable optical nonlinearity error, which provides the theoretical guidance for building a heterodyne laser measurement system with low optical nonlinearity.
{"title":"Study on formation and transformation of the optical nonlinearity harmonics in the heterodyne laser interferometer","authors":"Haijin Fu, Jiubin Tan, Z. Fan","doi":"10.1117/12.2181519","DOIUrl":"https://doi.org/10.1117/12.2181519","url":null,"abstract":"The accuracy of the heterodyne laser interferometer is strongly restricted by the optical nonlinearity harmonics. In order to mathematically reveal the formation and transformation mechanism of optical nonlinearity harmonics, the behavior of the nonlinearity harmonics is investigated with an optical nonlinearity expression based on the optical mixing parameters in the measurement signal. It is found that the formation and transformation of the first-order and second-order nonlinearity harmonics are closely related to the orthogonality of the optical mixing parameters. When the optical mixing parameters satisfy the orthogonal relation, the optical nonlinearity is purely the second-order harmonic whose peak-to-peak value is at least one order smaller than that of the first-order harmonic in the same optical mixing degree, indicating that a larger optical mixing level does not necessarily lead to a considerable optical nonlinearity error, which provides the theoretical guidance for building a heterodyne laser measurement system with low optical nonlinearity.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"208 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124685943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An eddy current excitation signal source was designed based on the linear control theory. By analyzing the interference and characteristics of signal source, a multi-input-single-output (MISO) feedback control system was designed and created using a lock-in amplifier, and an eddy current sensor was applied in the feedback loop of the system. As a result, the noise in the loop circuit was suppressed; this resolved the current instability problem in eddy current sensor. Furthermore, a mathematical model was established, and the stability and bandwidth of the system were verified by simulations. Compared with the traditional signal sources, experimental results show that this signal source had steadier current output, smaller temperature drift and stronger load capability. Therefore, the foil thickness measurement based on this signal source had a very high accuracy.
{"title":"An excitation signal source with anti-interference ability for eddy current testing","authors":"Guodong Jiang, Po Li","doi":"10.1117/12.2180731","DOIUrl":"https://doi.org/10.1117/12.2180731","url":null,"abstract":"An eddy current excitation signal source was designed based on the linear control theory. By analyzing the interference and characteristics of signal source, a multi-input-single-output (MISO) feedback control system was designed and created using a lock-in amplifier, and an eddy current sensor was applied in the feedback loop of the system. As a result, the noise in the loop circuit was suppressed; this resolved the current instability problem in eddy current sensor. Furthermore, a mathematical model was established, and the stability and bandwidth of the system were verified by simulations. Compared with the traditional signal sources, experimental results show that this signal source had steadier current output, smaller temperature drift and stronger load capability. Therefore, the foil thickness measurement based on this signal source had a very high accuracy.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127153987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
GPS based high accuracy speed meter for vehicles is a special type of GPS speed meter which uses Doppler Demodulation of GPS signals to calculate the speed of a moving target. It is increasingly used as reference equipment in the field of traffic speed measurement, but acknowledged standard calibration methods are still lacking. To solve this problem, this paper presents the set-ups of simulated calibration, field test signal replay calibration, and in-field test comparison with an optical sensor based non-contact speed meter. All the experiments were carried out on particular speed values in the range of (40-180) km/h with the same GPS speed meter. The speed measurement errors of simulated calibration fall in the range of ±0.1 km/h or ±0.1%, with uncertainties smaller than 0.02% (k=2). The errors of replay calibration fall in the range of ±0.1% with uncertainties smaller than 0.10% (k=2). The calibration results justify the effectiveness of the two methods. The relative deviations of the GPS speed meter from the optical sensor based noncontact speed meter fall in the range of ±0.3%, which validates the use of GPS speed meter as reference instruments. The results of this research can provide technical basis for the establishment of internationally standard calibration methods of GPS speed meters, and thus ensures the legal status of GPS speed meters as reference equipment in the field of traffic speed metrology.
{"title":"Calibration of GPS based high accuracy speed meter for vehicles","authors":"Yin Bai, Qiao Sun, L. Du, Mei Yu, J. Bai","doi":"10.1117/12.2178005","DOIUrl":"https://doi.org/10.1117/12.2178005","url":null,"abstract":"GPS based high accuracy speed meter for vehicles is a special type of GPS speed meter which uses Doppler Demodulation of GPS signals to calculate the speed of a moving target. It is increasingly used as reference equipment in the field of traffic speed measurement, but acknowledged standard calibration methods are still lacking. To solve this problem, this paper presents the set-ups of simulated calibration, field test signal replay calibration, and in-field test comparison with an optical sensor based non-contact speed meter. All the experiments were carried out on particular speed values in the range of (40-180) km/h with the same GPS speed meter. The speed measurement errors of simulated calibration fall in the range of ±0.1 km/h or ±0.1%, with uncertainties smaller than 0.02% (k=2). The errors of replay calibration fall in the range of ±0.1% with uncertainties smaller than 0.10% (k=2). The calibration results justify the effectiveness of the two methods. The relative deviations of the GPS speed meter from the optical sensor based noncontact speed meter fall in the range of ±0.3%, which validates the use of GPS speed meter as reference instruments. The results of this research can provide technical basis for the establishment of internationally standard calibration methods of GPS speed meters, and thus ensures the legal status of GPS speed meters as reference equipment in the field of traffic speed metrology.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"9446 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129030846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The stabilization and tracking line-of-sight with high accuracy is the chief specification and key function of the optic-electronic sight stabilization platform and it has an effect on the performance of loading equipment. The high-speed target is tracked with the shipboard azimuth and pitch optoelectronic platform. The compound-axis tracking servo control technique , the stabilization mirror system and the methods that compensates the azimuth by the rolling angle rate of motion carrier are used. The practice shows that the shipboard azimuth and pitch opto-electronic platform can realize high tracking precision.
{"title":"Control methods of improving tracking precision","authors":"Hua Liu, Yinxiao Miao, Ke Liu","doi":"10.1117/12.2181174","DOIUrl":"https://doi.org/10.1117/12.2181174","url":null,"abstract":"The stabilization and tracking line-of-sight with high accuracy is the chief specification and key function of the optic-electronic sight stabilization platform and it has an effect on the performance of loading equipment. The high-speed target is tracked with the shipboard azimuth and pitch optoelectronic platform. The compound-axis tracking servo control technique , the stabilization mirror system and the methods that compensates the azimuth by the rolling angle rate of motion carrier are used. The practice shows that the shipboard azimuth and pitch opto-electronic platform can realize high tracking precision.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129041844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Based on a dual interferometry frequency modulated wave laser (FMCW) laser ranging system, three steps to optimize the signal processing is proposed in this paper. The first step is signal re-sampling, by which the sampling signal is turned to be equal optical frequency intervals. The second step is splicing the re-sampled signal, by which can break though the tuning range of the laser source limitation. The last step is the all-phase pretreatment of the signal, its means that the all-phase Fast Fourier Transformation (apFFT) is used to handle the re-sampled signal, which could reduce the phase error of the signal. The experiments shows that the noise effect due to the tuning nonlinearity of laser can be reduced by re-sampling the signal, 50μm range resolution can be easily obtained by this method, the apFFT is more reliable and effective than FFT in the processing to reduce the phase error and improve the speed of operation.
{"title":"Optimization of the signal processing in frequency modulated continuous wave laser ranging system","authors":"Xiang-Fu Meng, Fumin Zhang, Xinghua Qu","doi":"10.1117/12.2180836","DOIUrl":"https://doi.org/10.1117/12.2180836","url":null,"abstract":"Based on a dual interferometry frequency modulated wave laser (FMCW) laser ranging system, three steps to optimize the signal processing is proposed in this paper. The first step is signal re-sampling, by which the sampling signal is turned to be equal optical frequency intervals. The second step is splicing the re-sampled signal, by which can break though the tuning range of the laser source limitation. The last step is the all-phase pretreatment of the signal, its means that the all-phase Fast Fourier Transformation (apFFT) is used to handle the re-sampled signal, which could reduce the phase error of the signal. The experiments shows that the noise effect due to the tuning nonlinearity of laser can be reduced by re-sampling the signal, 50μm range resolution can be easily obtained by this method, the apFFT is more reliable and effective than FFT in the processing to reduce the phase error and improve the speed of operation.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124225373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Haitao Wang, W. Zeng, Xianming Yang, Guiyun Tian, R. Guo, G. Hu, M. Wan
In this paper, a visualization system was proposed based on ultrasound excitation from a Q-switched pulsed YAG laser. The ultrasonic wave was received by a piezoelectric transducer. The electrical time-domain signal was analyzed in the Fourier-domain in order to detect a hole-like reflector in an austenitic stainless steel specimen. At a given receiver position, a piezoelectric transducer received the ultrasonic wave signal. The electrical time-domain signal was analyzed in the Fourier-domain. The experimental research on the influence of the relative position distance between the laser excitation spot and the defect of the test specimen was conducted. The experimental results showed a significant geometrical imaging of the reflector shape with the scanned data. Therefore, a quantitative laser ultrasound visualization system was realized along with the spectral analysis. It will provide a new method of defects detection and sizing.
{"title":"Study on the detection of a cylindrical surface-breaking bore-hole reflector based on laser ultrasonic technology","authors":"Haitao Wang, W. Zeng, Xianming Yang, Guiyun Tian, R. Guo, G. Hu, M. Wan","doi":"10.1117/12.2180596","DOIUrl":"https://doi.org/10.1117/12.2180596","url":null,"abstract":"In this paper, a visualization system was proposed based on ultrasound excitation from a Q-switched pulsed YAG laser. The ultrasonic wave was received by a piezoelectric transducer. The electrical time-domain signal was analyzed in the Fourier-domain in order to detect a hole-like reflector in an austenitic stainless steel specimen. At a given receiver position, a piezoelectric transducer received the ultrasonic wave signal. The electrical time-domain signal was analyzed in the Fourier-domain. The experimental research on the influence of the relative position distance between the laser excitation spot and the defect of the test specimen was conducted. The experimental results showed a significant geometrical imaging of the reflector shape with the scanned data. Therefore, a quantitative laser ultrasound visualization system was realized along with the spectral analysis. It will provide a new method of defects detection and sizing.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"57 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120860111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Li Cai, Hai-yan Lu, Wei-wei Zhan, Zehn-yu Yang, Xiu Wang
This paper describes the quartz horizontal pendulum tiltmeter system based on CCD to convert traditional analog quartz horizontal pendulum tiltmeter to digital quartz horizontal pendulum tiltmeter, the measurement principle and application of CCD image sensor in this system. The system has the advantages of high resolution, fast response and it can realize the real-time observation. In the actual application, the system can provide valuable precursory information for the work of earthquake analysis and prediction.
{"title":"Design of the digital quartz horizontal pendulum tiltmeter based on CCD","authors":"Li Cai, Hai-yan Lu, Wei-wei Zhan, Zehn-yu Yang, Xiu Wang","doi":"10.1117/12.2180685","DOIUrl":"https://doi.org/10.1117/12.2180685","url":null,"abstract":"This paper describes the quartz horizontal pendulum tiltmeter system based on CCD to convert traditional analog quartz horizontal pendulum tiltmeter to digital quartz horizontal pendulum tiltmeter, the measurement principle and application of CCD image sensor in this system. The system has the advantages of high resolution, fast response and it can realize the real-time observation. In the actual application, the system can provide valuable precursory information for the work of earthquake analysis and prediction.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115880452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Bo, F. Duan, Fan Feng, C. Lv, Fu Xiao, Tingting Huang
A fiber-optic sinusoidal phase modulating (SPM) interferometer was proposed for the acquisition and reconstruction of three-dimensional (3-D) surface profile. Sinusoidal phase modulation was induced by controlling the injection current of light source. The surface profile was constructed on the basis of fringe projection. Fringe patterns are vulnerable to external disturbances such as mechanical vibration and temperature fluctuation, which cause phase drift in the interference signal and decrease measuring accuracy. A closed-loop feedback phase compensation system was built. In the subsystem, the initial phase of the interference signal, which was caused by the initial optical path difference between interference arms, could be demodulated using phase generated carrier (PGC) method and counted out using coordinated rotation digital computer (CORDIC) , then a compensation voltage was generated for the PZT driver. The bias value of external disturbances superimposed on fringe patterns could be reduced to about 50 mrad, and the phase stability for interference fringes was less than 6 mrad. The feasibility for real-time profile measurement has been verified.
{"title":"Phase compensation with fiber optic surface profile acquisition and reconstruction system","authors":"E. Bo, F. Duan, Fan Feng, C. Lv, Fu Xiao, Tingting Huang","doi":"10.1117/12.2180668","DOIUrl":"https://doi.org/10.1117/12.2180668","url":null,"abstract":"A fiber-optic sinusoidal phase modulating (SPM) interferometer was proposed for the acquisition and reconstruction of three-dimensional (3-D) surface profile. Sinusoidal phase modulation was induced by controlling the injection current of light source. The surface profile was constructed on the basis of fringe projection. Fringe patterns are vulnerable to external disturbances such as mechanical vibration and temperature fluctuation, which cause phase drift in the interference signal and decrease measuring accuracy. A closed-loop feedback phase compensation system was built. In the subsystem, the initial phase of the interference signal, which was caused by the initial optical path difference between interference arms, could be demodulated using phase generated carrier (PGC) method and counted out using coordinated rotation digital computer (CORDIC) , then a compensation voltage was generated for the PZT driver. The bias value of external disturbances superimposed on fringe patterns could be reduced to about 50 mrad, and the phase stability for interference fringes was less than 6 mrad. The feasibility for real-time profile measurement has been verified.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"381 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115898946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jianshuan Li, M. Zhang, Ming-zhao He, Dongjing Miao, Xiangrui Deng, Lianfu Li
Abbe error is the inherent systematic error in all large-scale laser comparators because the standard laser axis is not in line with measured optical axis. Any angular error of the moving platform will result in the offset from the measured optical axis to the standard laser axis. This paper describes to an algorithm which could be used to calculate the displacement of an equivalent standard laser interferometer and to eliminate an Abbe error. The algorithm could also be used to reduce the Abbe error of a large-scale laser comparator. Experimental results indicated that the uncertainty of displacement measurement due to Abbe error could be effectively reduced when the position error of the measured optical axis was taken into account.
{"title":"Elimination of Abbe error method of large-scale laser comparator","authors":"Jianshuan Li, M. Zhang, Ming-zhao He, Dongjing Miao, Xiangrui Deng, Lianfu Li","doi":"10.1117/12.2181500","DOIUrl":"https://doi.org/10.1117/12.2181500","url":null,"abstract":"Abbe error is the inherent systematic error in all large-scale laser comparators because the standard laser axis is not in line with measured optical axis. Any angular error of the moving platform will result in the offset from the measured optical axis to the standard laser axis. This paper describes to an algorithm which could be used to calculate the displacement of an equivalent standard laser interferometer and to eliminate an Abbe error. The algorithm could also be used to reduce the Abbe error of a large-scale laser comparator. Experimental results indicated that the uncertainty of displacement measurement due to Abbe error could be effectively reduced when the position error of the measured optical axis was taken into account.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131024657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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