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Laboratory demonstration of geopotential measurement using transportable optical clocks 被引量:1
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作者 刘道信 曹健 +6 位作者 袁金波 崔凯枫 袁易 张平 晁思嘉 舒华林 黄学人 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第1期272-277,共6页
We report an experimental demonstration of geopotential difference measurement using a pair of transportable ^(40)Ca^(+) optical clocks(TOC-729-1 and TOC-729-3)in the laboratory,each of them has an uncertainty of 1.3&... We report an experimental demonstration of geopotential difference measurement using a pair of transportable ^(40)Ca^(+) optical clocks(TOC-729-1 and TOC-729-3)in the laboratory,each of them has an uncertainty of 1.3×10^(−17) and an instability of 4.8×10^(−15)/√τ.Referenced to a stationary clock of TOC-729-1,the geopotential difference measurements are realized by moving TOC-729-3 to three different locations and the relevant altitude differences are measured with uncertainties at the level of 20 cm.After correcting the systematic shifts(including gravitational red shift),the two-clock frequency difference is measured to be–0.7(2.2)×10^(−17),considering both the statistic(1.0×10^(−17))and the systematic(1.9×10^(−17))uncertainties.The frequency difference between these two clocks is within their respective uncertainties,verifying the reliability of transportable ^(40)Ca^(+) optical clocks at the low level of 10^(−17). 展开更多
关键词 geopotential difference measurement transportable optical clock repeatability evaluation of clocks
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Finesse measurement for high-power optical enhancement cavity
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作者 陆心怡 柳兴 +3 位作者 田其立 王焕 汪嘉俊 颜立新 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第1期414-421,共8页
Finesse is a critical parameter for describing the characteristics of an optical enhancement cavity(OEC). This paper first presents a review of finesse measurement techniques, including a comparative analysis of the a... Finesse is a critical parameter for describing the characteristics of an optical enhancement cavity(OEC). This paper first presents a review of finesse measurement techniques, including a comparative analysis of the advantages, disadvantages, and potential limitations of several main methods from both theoretical and practical perspectives. A variant of the existing method called the free spectral range(FSR) modulation method is proposed and compared with three other finesse measurement methods, i.e., the fast-switching cavity ring-down(CRD) method, the rapidly swept-frequency(SF) CRD method, and the ringing effect method. A high-power OEC platform with a high finesse of approximately 16000 is built and measured with the four methods. The performance of these methods is compared, and the results show that the FSR modulation method and the fast-switching CRD method are more suitable and accurate than the other two methods for high-finesse OEC measurements. The CRD method and the ringing effect method can be implemented in open loop using simple equipment and are easy to perform. Additionally, recommendations for selecting finesse measurement methods under different conditions are proposed, which benefit the development of OEC and its applications. 展开更多
关键词 optical enhancement cavity finesse measurement cavity ring-down ringing effect
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A novel indirect optical method for rock stress measurement using microdeformation field analysis
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作者 Yujie Feng Peng-Zhi Pan +2 位作者 Zhaofeng Wang Xufeng Liu Shuting Miao 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第9期3616-3628,共13页
Stress measurement plays a crucial role in geomechanics and rock engineering,especially for the design and construction of large-scale rock projects.This paper presents a novel method,based on the traditional stress r... Stress measurement plays a crucial role in geomechanics and rock engineering,especially for the design and construction of large-scale rock projects.This paper presents a novel method,based on the traditional stress relief approach,for indirectly measuring rock stress using optical techniques.The proposed method allows for the acquisition of full-field strain evolution on the borehole’s inner wall before and after disturbance,facilitating the determination of three-dimensional(3D)stress information at multiple points within a single borehole.The study focuses on presenting the method’s theoretical framework,laboratory validation results,and equipment design conception.The theoretical framework comprises three key components:the optical imaging method of the borehole wall,the digital image correlation(DIC)method,and the stress calculation procedure.Laboratory validation tests investigate strain field distribution on the borehole wall under varying stress conditions,with stress results derived from DIC strain data.Remarkably,the optical method demonstrates better measurement accuracy during the unloading stage compared to conventional strain gauge methods.At relatively high stress levels,the optical method demonstrates a relative error of less than 7%and an absolute error within 0.5 MPa.Furthermore,a comparative analysis between the optical method and the conventional contact resistance strain gauge method highlights the optical method’s enhanced accuracy and stability,particularly during the unloading stage.The proposed optical stress measurement device represents a pioneering effort in the application of DIC technology to rock engineering,highlighting its potential to advance stress measurement techniques in the field. 展开更多
关键词 Rock stress measurement optical technology Digital image correlation(DIC)technology Micro-deformation field
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Phase-Based Optical Flow Method with Optimized Parameter Settings for Enhancing Displacement Measurement Adaptability
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作者 Zhaoxin Peng Menglian Liu +2 位作者 Zhiliang Wang Wei Liu Xian Wang 《Open Journal of Applied Sciences》 2024年第5期1165-1184,共20页
To enhance the applicability and measurement accuracy of phase-based optical flow method using complex steerable pyramids in structural displacement measurement engineering applications, an improved method of optimizi... To enhance the applicability and measurement accuracy of phase-based optical flow method using complex steerable pyramids in structural displacement measurement engineering applications, an improved method of optimizing parameter settings is proposed. The optimized parameters include the best measurement points of the Region of Interest (ROI) and the levels of pyramid filters. Additionally, to address the issue of updating reference frames in practical applications due to the difficulty in estimating the maximum effective measurement value, a mechanism for dynamically updating reference frames is introduced. Experimental results demonstrate that compared to representative image gradient-based displacement measurement methods, the proposed method exhibits higher measurement accuracy in engineering applications. This provides reliable data support for structural damage identification research based on vibration signals and is expected to broaden the engineering application prospects for structural health monitoring. 展开更多
关键词 Displacement measurement Phase-Based optical Flow Optimized Parameter Setting
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The Evolution of Landscape Patterns of and Optimization Measures for Urban Core Areas Against the Background of Urbanization: A Case Study of Yangling Demonstration Zone
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作者 TANG Ying ZHANG Pei SHI Chengyong 《Journal of Landscape Research》 2018年第4期67-71,77,共6页
Studying tiie urban landscape pattern plays a crucial role in scientific land use and management and in improving the urban ecological environment In this paper, AutoCAD, ArcGIS, Fragstats, and other software were u... Studying tiie urban landscape pattern plays a crucial role in scientific land use and management and in improving the urban ecological environment In this paper, AutoCAD, ArcGIS, Fragstats, and other software were used to analyse the data of the fourth phase of land use in the core atea of Yangling Demonstration Zone. The results showed that: ① in the core area, the percentage of construction land incteased from 18.22% to 61.72%, and the percentage of agricultufal land decreased from 58.36% to 11.14%. And the fafm land was fragmented, and traffic connectivily was strengthened. The afea of garden land was reduced from 251.89 hm2 to 50.38 hm^2, and the landscape metric of forest land showed an inverted V-shaped curve. ②The year 2009 in four phases witnessed the greatest landscape fragmentation, both Edge Density (ED) and Ingest Patch Index (LPI) increased, and human interference enhanced the overall landscape complexity. Measures were fotmulated in terms of deaf development goals, optimized allocation of land resoutces, effective protection of ecological ted lines, and definite ecological responsibility, so as to optimize the urban landscape pattern. 展开更多
关键词 Yangling demonstration Zone Urban core area Changes in landscape patterns Optimization measures
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Strategic Measures for Implementing 300 Demonstration Projects to Lead the Construction of Modern Agricultural Industrial Clusters with Output of 100 Billion Yuan
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作者 Ying GAO Changjia PENG +4 位作者 Fengyuan LI Jun LUO Jiawei DU Feng LUO Ning LU 《Asian Agricultural Research》 2018年第11期14-22,共9页
To carefully implement the rural revitalization strategy,further promote the structural reform of the agricultural supply front,implement the "155 Development Strategy",speed up the cultivation of the modern... To carefully implement the rural revitalization strategy,further promote the structural reform of the agricultural supply front,implement the "155 Development Strategy",speed up the cultivation of the modern agricultural industrial clusters with output of 100 billion yuan,and constantly consolidate the industrial foundation of the " Second City in Chengdu-Chongqing Line",the Municipal Party Committee and the Municipal Government of Nanchong City decided to implement the " 300 Demonstration Projects" of modern agriculture. It firmly grasps the " bull nose"( key part) of the project,energetically implements the construction of 100 modern circular agricultural demonstration parks,100 agricultural leading enterprises with output value of 100 billion yuan,and 100 agricultural new business model demonstration projects( hereinafter referred to as 300 Demonstration Projects),to realize the goal of the output value of the modern agriculture industrial clusters of Nanchong City exceeds 100 billion yuan in 2020. 展开更多
关键词 农村 振兴战略 供应链 结构改革
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A New Method for In-Situ Measurement of Internal Solitary Waves Based on the Stimulated Raman Scattering in Optical Fibers
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作者 WANG Jing ZHANG Meng +4 位作者 MIAO Xiangying YANG Zhonghao LI Zhixin HUO Dianheng MIAO Hongli 《Journal of Ocean University of China》 SCIE CAS CSCD 2023年第3期658-664,共7页
In-situ measurement of internal solitary waves(ISWs)is complicated in the ocean due to their randomness.At present,the ISWs are mainly detected by the chain structure of conductivity-temperature-depth systems(CTDs)or ... In-situ measurement of internal solitary waves(ISWs)is complicated in the ocean due to their randomness.At present,the ISWs are mainly detected by the chain structure of conductivity-temperature-depth systems(CTDs)or temperature sensors.The high cost limits the spatial resolution,which ultimately affects the measuring accuracy of the ISW amplitude.In this paper,we developed an experimental measurement system for detecting ISWs based on the stimulated Raman scattering in distributed optical fibers.This system has the advantages of high precision,low cost,and easy operation.The experimental results show that the system is consistent with CTDs in the measurement of vertical ocean temperature variation.The spatial resolution of the system can reach 1.0 m and the measuring accuracy of temperature is 0.2℃.We successfully detected 3 ISWs by the system in the South China Sea and two optical remote sensing images collected on May 18,2021,the same day of two detected ISWs,verify the occurrence of the measured ISWs.We used the image pairs method to calculate the phase velocity of ISW and the result is 1.71 ms^(-1).By extracting the distances between wave packets,it can be found that the semi-diurnal tide generates the detected ISWs.The impact of the tidal current velocity on the ISW in amplitude is undeniable.Undoubtedly,the system has a great application prospect for detecting ISWs and other dynamic phenomena in the ocean. 展开更多
关键词 internal solitary wave optical fiber stimulated Raman scattering in-situ measurement
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Quantum-enhanced optical precision measurement assisted by low-frequency squeezed vacuum states
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作者 康国辉 冯晋霞 +2 位作者 程琳 李渊骥 张宽收 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第10期438-442,共5页
Stable low-frequency squeezed vacuum states at a wavelength of 1550 nm were generated.By controlling the squeezing angle of the squeezed vacuum states,two types of low-frequency quadrature-phase squeezed vacuum states... Stable low-frequency squeezed vacuum states at a wavelength of 1550 nm were generated.By controlling the squeezing angle of the squeezed vacuum states,two types of low-frequency quadrature-phase squeezed vacuum states and quadrature-amplitude squeezed vacuum states were obtained using one setup respectively.A quantum-enhanced fiber Mach–Zehnder interferometer(FMZI)was demonstrated for low-frequency phase measurement using the generated quadrature-phase squeezed vacuum states that were injected.When phase modulation was measured with the quantumenhanced FMZI,there were above 3 dB quantum improvements beyond the shot-noise limit(SNL)from 40 kHz to 200 kHz,and 2.3 dB quantum improvement beyond the SNL at 20 kHz was obtained.The generated quadrature-amplitude squeezed vacuum state was applied to perform low-frequency amplitude modulation measurement for sensitivity beyond the SNL based on optical fiber construction.There were about 2 dB quantum improvements beyond the SNL from 60 kHz to 200 kHz.The current scheme proves that quantum-enhanced fiber-based sensors are feasible and have potential applications in high-precision measurements based on fiber,particularly in the low-frequency range. 展开更多
关键词 squeezed vacuum states fiber Mach–Zehnder interferometer optical precision measurement
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Measuring small longitudinal phase shifts via weak measurement amplification
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作者 徐凯 胡晓敏 +7 位作者 胡孟军 王宁宁 张超 黄运锋 柳必恒 李传锋 郭光灿 张永生 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第3期105-111,共7页
Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted ... Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted into phase signals,it is interesting and important to consider measuring small longitudinal phase shifts by using weak measurement.Here,we propose and experimentally demonstrate a novel weak measurement amplification-based small longitudinal phase estimation,which is suitable for polarization interferometry.We realize one order of magnitude amplification measurement of a small phase signal directly introduced by a liquid crystal variable retarder and show that it is robust to the imperfection of interference.Besides,we analyze the effect of magnification error which is never considered in the previous works,and find the constraint on the magnification.Our results may find important applications in high-precision measurements,e.g.,gravitational wave detection. 展开更多
关键词 weak measurement phase estimation quantum optics
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Precise Optical Fiber Length Measurement System Based on Fresnel Reflection
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作者 Firat Ertac Durak Arif Basgumus +1 位作者 Serif Ali Sadik Ahmet Altuncu 《Journal of Electrical Engineering》 2016年第3期128-132,共5页
In this study, a precise optical fiber length measurement system is proposed. The measurement technique is based on the measurement of relative Fresnel reflected light intensity in a test fiber. Time delayed optical r... In this study, a precise optical fiber length measurement system is proposed. The measurement technique is based on the measurement of relative Fresnel reflected light intensity in a test fiber. Time delayed optical reflected pulses are obtained from a single nanosecond pulse injected at the input due to the difference in lengths of the reference and test fibers. The lengths of the different optical fibers have been measured with this technique with high resolution and fast response time. The measured results show that, the proposed technique has a comparable performance with the well-known length measurement systems. 展开更多
关键词 Fresnel reflection nanosecond pulse optical fiber length measurement time delayed pulses.
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Comparing different light-emitting diodes as light sources for long path differential optical absorption spectroscopy NO_2 and SO_2 measurements 被引量:1
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作者 陈嘉乐 凌六一 +7 位作者 Andreas Hartl 郑尼娜 Gerrit Kuhlmann 秦敏 孙友文 谢品华 刘文清 Mark Wenig 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第11期587-596,共10页
In this paper, we present a comparison of different light-emitting diodes (LEDs) as the light source for long path differential optical absorption spectroscopy (LP-DOAS) atmospheric trace gas measurements. In our ... In this paper, we present a comparison of different light-emitting diodes (LEDs) as the light source for long path differential optical absorption spectroscopy (LP-DOAS) atmospheric trace gas measurements. In our study, we use a fiberoptic design, where high power LEDs used as the light source are coupled into the telescope using a Y shape fiber bundle. Two blue and one ultraviolet (UV) LEDs with different emission wavelength ranges are tested for NO2 and SO2 measurements. The detailed description of the instrumental setup, the NO2 and SO2 retrieval procedure, the error analysis, and the preliminary results from the measurements carried out in Science Island, Hefei, Anhui, China are presented. Our first measurement results show that atmospheric NO2 and SO2 have strong temporal variations in that area and that the measurement accuracy is strongly dependent on the visibility conditions. The measured NO2 and SO2 data are compared to the Ozone Monitoring Instrument (OMI) satellite observations. The results show that the OMI NO2 product underestimates the ground level NO2 by 45%, while the OMI SO2 data are highly influenced by clouds and aerosols, which can lead to large biases in the ground level concentrations. During the experiment, the mixing ratios of the atmospheric NO2 and SO2 vary from 8 ppbv to 36 ppbv and from 3 ppbv to 18 ppbv, respectively. 展开更多
关键词 light-emitting diode fiber optic designed telescope NO2 measurement SO2 measurement
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Plastic optical fiber refractometer for continuous refractive index measurement
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作者 景宁 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2016年第2期103-105,共3页
This paper investigated the continuous measurement of a refractive index(RI)sensor based on macrobending microoptical plastic fiber(m-POF).The sensing properties of the RI sensor depend on the structure parameter,whic... This paper investigated the continuous measurement of a refractive index(RI)sensor based on macrobending microoptical plastic fiber(m-POF).The sensing properties of the RI sensor depend on the structure parameter,which is the ratio of macrobending radius of m-POF to the radius of fiber itself.The ratio changes with the measurement time increasing because of the water absorption,which introduces an maximum measurement deviation of 7.3×10^(-5) RIU when the immersion time exceeds 40 h.This work indicates that for the sensors based on POF,the measurement time must be taken into consideration for continuous measurement. 展开更多
关键词 plastic optical fiber(POF) water absorption continuous measurement
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A method for phase reconstruction in optical three-dimensional shape measurement
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作者 乔闹生 贺志 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第9期267-270,共4页
In optical three-dimensional shape measurement, a method of improving the measurement precision for phase reconstruction without phase unwrapping is analyzed in detail. Intensities of any five consecutive pixels that ... In optical three-dimensional shape measurement, a method of improving the measurement precision for phase reconstruction without phase unwrapping is analyzed in detail. Intensities of any five consecutive pixels that lie in the x-axis direction of the phase domain are given. Partial derivatives of the phase function in the x- and y-axis directions are obtained with a phase-shifting mechanism, the origin of which is analysed. Furthermore, to avoid phase unwrapping in the phase reconstruction, we derive the gradient of the phase function and perform a two-dimensional integral along the x- and y-axis directions. The reconstructed phase can be obtained directly by performing numerical integration, and thus it is of great convenience for phase reconstruction. Finally, the results of numerical simulations and practical experiments verify the correctness of the proposed method. 展开更多
关键词 phase reconstruction optical three-dimensional shape measurement measurement pre-cision
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Highly sensitive digital optical sensor with large measurement range based on the dual-microring resonator with waveguide-coupled feedback 被引量:3
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作者 向星烨 王葵如 +3 位作者 苑金辉 晋博源 桑新柱 余重秀 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第3期284-288,共5页
We propose a novel high-performance digital optical sensor based on the Mach-Zehnder interferential effect and the dual-microring resonators with the waveguide-coupled feedback. The simulation results show that the se... We propose a novel high-performance digital optical sensor based on the Mach-Zehnder interferential effect and the dual-microring resonators with the waveguide-coupled feedback. The simulation results show that the sensitivity of the sensor can be orders of magnitude higher than that of aconventional sensor, and high quality factor is not critical in it. Moreover, by optimizing the length of the feedback waveguide to be equal to the perimeter of the ring, the measurement range of the proposed sensor is twice as much as that of the conventional sensor in the weak coupling case. 展开更多
关键词 optical sensor microring resonator high sensitivity large measurement range
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Simultaneous estimation of aerosol optical constants and size distribution from angular light-scattering measurement signals 被引量:3
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作者 Zhen-Zong He Dong Liang +1 位作者 Jun-Kui Mao Xing-Si Han 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第5期564-572,共9页
The angular light-scattering measurement(ALSM) method combined with an improved artificial bee colony algorithm is introduced to determine aerosol optical constants and aerosol size distribution(ASD) simultaneousl... The angular light-scattering measurement(ALSM) method combined with an improved artificial bee colony algorithm is introduced to determine aerosol optical constants and aerosol size distribution(ASD) simultaneously. Meanwhile, an optimized selection principle of the ALSM signals based on the sensitivity analysis and principle component analysis(PCA)is proposed to improve the accuracy of the retrieval results. The sensitivity analysis of the ALSM signals to the optical constants or characteristic parameters in the ASD is studied first to find the optimized selection region of measurement angles. Then, the PCA is adopted to select the optimized measurement angles within the optimized selection region obtained by sensitivity analysis. The investigation reveals that, compared with random selection measurement angles, the optimized selection measurement angles can provide more useful measurement information to ensure the retrieval accuracy. Finally,the aerosol optical constants and the ASDs are reconstructed simultaneously. The results show that the retrieval accuracy of refractive indices is better than that of absorption indices, while the characteristic parameters in ASDs have similar retrieval accuracy. Moreover, the retrieval accuracy in studying L-N distribution is a little better than that in studying Gamma distribution for the difference of corresponding correlation coefficient matrixes of the ALSM signals. All the results confirm that the proposed technique is an effective and reliable technique in estimating the aerosol optical constants and ASD simultaneously. 展开更多
关键词 angular light-scattering measurement method aerosol optical constants aerosol size distribution inverse radiation problem
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First Evaluation and Frequency Measurement of the Strontium Optical Lattice Clock at NIM 被引量:13
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作者 林弋戈 王强 +7 位作者 李烨 孟飞 林百科 臧二军 孙震 房芳 李天初 方占军 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第9期17-20,共4页
An optical lattice clock based on 87Sr is built at National Institute of Metrology (NIM) of China. The systematic frequency shifts of the clock are evaluated with a total uncertainty of 2.3×10-16. To measure it... An optical lattice clock based on 87Sr is built at National Institute of Metrology (NIM) of China. The systematic frequency shifts of the clock are evaluated with a total uncertainty of 2.3×10-16. To measure its absolute frequency with respect to NIM's cesium fountain clock NIM5, the frequency of a flywheel H-maser of NIM5 is transferred to the Sr laboratory through a 50-kin-long fiber. reference frequency of this H-maser, is used for the optical this Sr clock is measured to be 429228004229873.7(1.4)Hz. A fiber optical frequency comb, phase-locked to the frequency measurement. The absolute frequency of 展开更多
关键词 AOM First Evaluation and Frequency measurement of the Strontium optical Lattice Clock at NIM
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Magic Wavelength Measurement of the ^(87)Sr Optical Lattice Clock at NIM 被引量:2
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作者 王强 林弋戈 +5 位作者 孟飞 李烨 林百科 臧二军 李天初 方占军 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第10期45-48,共4页
We report on the magic wavelength measurement of our optical lattice clock based on fermion strontium atoms at the National Institute of Metrology (NIM). A Ti:sapphire solid state laser locked to a reference cavity... We report on the magic wavelength measurement of our optical lattice clock based on fermion strontium atoms at the National Institute of Metrology (NIM). A Ti:sapphire solid state laser locked to a reference cavity inside a temperature-stabilized vacuum chamber is employed to generate the optical lattice. The laser frequency is measured by an erbium fiber frequency comb. The trap depth is modulated by varying the lattice laser power via an acousto-optic modulator. We obtain the frequency shift coefficient at this lattice wavelength by measuring the diffbrential frequency shift of the clock transition of the strontium atoms at different trap depths, and the frequency shift coefficient at this lattice wavelength is obtained. We measure the frequency shift coefficients at different lattice frequencies around the magic wavelength and linearly fit the measurement data, and the magic wavelength is calculated to be 368554672(44)MHz. 展开更多
关键词 of is as on by BE Magic Wavelength measurement of the Sr optical Lattice Clock at NIM
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A diode laser spectrometer at 634 nm and absolute frequency measurements using optical frequency comb 被引量:1
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作者 伊林 袁杰 +5 位作者 齐向晖 陈文兰 周大伟 周通 周小计 陈徐宗 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第4期1409-1412,共4页
This paper reports that two identical external-cavity-diode-laser (ECDL) based spectrometers are constructed at 634nm referencing on the hyperfine B-X transition R(80)8-4 of 127I2. The lasers are stabilized on the... This paper reports that two identical external-cavity-diode-laser (ECDL) based spectrometers are constructed at 634nm referencing on the hyperfine B-X transition R(80)8-4 of 127I2. The lasers are stabilized on the Doppler-free absorption signals using the third-harmonic detection technique. The instability of the stabilized laser is measured to be 2.8 × 10^-12 (after 1000 s) by counting the beat note between the two lasers. The absolute optical frequency of the transition is, for the first time, determined to be 472851936189.5 kHz by using an optical frequency comb referenced on the microwave caesium atomic clock. The uncertainty of the measurement is less than 4.9 kHz. 展开更多
关键词 frequency standard optical frequency comb absolute frequency measurement atomicclock
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Repeatability of in-vitro optical quality measurements of intraocular lenses with a deflectometry technique effect of the toricity 被引量:1
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作者 Teresa Ferrer-Blasco Alberto Dominguez-Vicent +3 位作者 Santiago Garcia-Lazaro Maria Amparo Diez-Ajenjo Jose F.Alfonso Jose J.Esteve-Taboada 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2018年第7期1139-1144,共6页
AIM: To evaluate the repeatability of an optical device for measuring the Zernike coefficients of toric intraocular lenses(IOLs) and assess whether its toricity has any impact in its repeatability. METHODS: An exp... AIM: To evaluate the repeatability of an optical device for measuring the Zernike coefficients of toric intraocular lenses(IOLs) and assess whether its toricity has any impact in its repeatability. METHODS: An experienced technician used the NIMO TR1504 to measure the Zernike coefficients 30 times for an aperture of 4.50 mm for all lenses included. The IOLs included were divided into two group: toric and nontoric ones. The cylindrical powers of the toric lenses included in the present study were 1.00, 1.50, 2.25, 3.00 and 3.75 D. Finally, the repeatability of the NIMO TR1504 was described in terms of within subject standard deviation(Sw) and repeatability limit. RESULTS: The Sw was smaller than 0.011 μm for both lens groups and all Zernike coefficients, and the difference between both groups was smaller than 0.004 μm for all Zernike coefficients. Regarding the repeatability limit, this value was smaller than 0.025 μm for the toric lens group, and smaller than 0.031 μm for the non-toric lens one for all Zernike coefficients. Furthermore, the maximum difference between both lens groups was 0.010 μm. CONCLUSION: The repeatability of the NIMO TR1504 to measure the optical quality is high and independent of the lens toricity. These results reflect that this system is robust and could be used to measure the in-vitro optical quality of either toric or non-toric IOLs. 展开更多
关键词 in-vitro measurements optical quality intraocular lens REPEATABILITY
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Fringe Projection Measurement System in Reverse Engineering 被引量:1
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作者 林朝辉 何海涛 +3 位作者 郭红卫 陈明仪 石璇 俞涛 《Journal of Shanghai University(English Edition)》 CAS 2005年第2期153-158,共6页
Acquisition of physical data with high precision is a key step in reverse engineering (RE). It is an important stimulative for the progress of reverse engineering with which various digitizing devices are invent ed,... Acquisition of physical data with high precision is a key step in reverse engineering (RE). It is an important stimulative for the progress of reverse engineering with which various digitizing devices are invent ed, developed and made applicable. This paper introduces a three dimensional opt ical measurement method based on digital fringe projection technique in RE to im prove the technique through its application. A practical example is presented an d the result demonstrates the applicability and feasibility of the measurement s ystem as well as the reliability and validity of relevant methods and algorithms . 展开更多
关键词 reverse engineering 3D optical measurement fring e projection multi-aperture overlap-scanning technique (MAOST) surface fitti ng.
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