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Instrumentation, measurement, and metrology|173 Article(s)
Large-scale absolute distance measurement with dual free-running all-polarization-maintaining femtosecond fiber lasers
Yuepeng Li, Yawen Cai, Runmin Li, Haosen Shi, Haochen Tian, Mingzhao He, Youjian Song, and Minglie Hu
We demonstrate a robust femtosecond LIDAR setup by using two free-running environmentally stable all-polarization-maintaining nonlinear amplified loop mirror mode-locked fiber lasers. Based on the asynchronous optical sampling method, a ranging accuracy of ±2 μm within 65 m has been achieved, as tested in an 80-m-long underground optical tunnel. Through the Kalman filter in real-time data processing, the measurement accuracy can be maintained at a 200 Hz update rate. This setup provides a practical tool for various large-scale industrial and astronomical ranging applications. We demonstrate a robust femtosecond LIDAR setup by using two free-running environmentally stable all-polarization-maintaining nonlinear amplified loop mirror mode-locked fiber lasers. Based on the asynchronous optical sampling method, a ranging accuracy of ±2 μm within 65 m has been achieved, as tested in an 80-m-long underground optical tunnel. Through the Kalman filter in real-time data processing, the measurement accuracy can be maintained at a 200 Hz update rate. This setup provides a practical tool for various large-scale industrial and astronomical ranging applications.
Chinese Optics Letters
- Publication Date: Sep. 10, 2019
- Vol. 17, Issue 9, 091202 (2019)
Absolute cryogenic radiometer for high accuracy optical radiant power measurement in a wide spectral range
Haiyong Gan, Yingwei He, Xiangliang Liu, Nan Xu, Houping Wu, Guojin Feng, Wende Liu, and Yandong Lin
An absolute cryogenic radiometer (ACR) with a detachable optical window was designed and built for high accuracy optical radiant power measurement and photodetector spectral responsivity calibration. The ACR receiver is an electroplated pure copper cavity with a 50-μm-thick wall and inner surface coated with a specular black polymer material mixed with highly dispersible carbon nanotubes. The absorptivity of the cavity receivers was evaluated to be ≥0.9999 in the 250 nm–16 μm wavelength range and ≥0.99995 in 500 nm–16 μm. The cavity receiver works at the temperature of ～5.2 K with nanowatt-level noise-equivalent power. The relative standard uncertainty is 0.041% for the measurement of ～100 μW optical radiant power (250 nm–16 μm) and 0.015% for ～1 mW (500 nm–16 μm). An absolute cryogenic radiometer (ACR) with a detachable optical window was designed and built for high accuracy optical radiant power measurement and photodetector spectral responsivity calibration. The ACR receiver is an electroplated pure copper cavity with a 50-μm-thick wall and inner surface coated with a specular black polymer material mixed with highly dispersible carbon nanotubes. The absorptivity of the cavity receivers was evaluated to be ≥0.9999 in the 250 nm–16 μm wavelength range and ≥0.99995 in 500 nm–16 μm. The cavity receiver works at the temperature of ～5.2 K with nanowatt-level noise-equivalent power. The relative standard uncertainty is 0.041% for the measurement of ～100 μW optical radiant power (250 nm–16 μm) and 0.015% for ～1 mW (500 nm–16 μm).
Chinese Optics Letters
- Publication Date: Sep. 10, 2019
- Vol. 17, Issue 9, 091201 (2019)
All-fiber pulsed laser Doppler vibrometer development based on time-domain chopping techniques
Shisong Wu, Yuanyang Li, Tao Lü, Hongkai Chen, Chunhui Yan, Tingfeng Wang, and Jin Guo
A 1550 nm all-fiber pulsed laser Doppler vibrometer (LDV) based on time-domain chopping techniques is developed to overcome demodulation failures caused by multipath interference. The system adopts an adjustable configuration on pulse duration and pulse repetition frequency according to the distance. An experiment is carried out at a 25 m standoff with pulse duration of 80 ns, single pulse energy of 0.4 nJ, and pulse repetition frequency of 1 MHz. A waveform and spectrogram of the demodulated voice show that the pulsed LDV system has a good performance in long-range voice listening. A 1550 nm all-fiber pulsed laser Doppler vibrometer (LDV) based on time-domain chopping techniques is developed to overcome demodulation failures caused by multipath interference. The system adopts an adjustable configuration on pulse duration and pulse repetition frequency according to the distance. An experiment is carried out at a 25 m standoff with pulse duration of 80 ns, single pulse energy of 0.4 nJ, and pulse repetition frequency of 1 MHz. A waveform and spectrogram of the demodulated voice show that the pulsed LDV system has a good performance in long-range voice listening.
Chinese Optics Letters
- Publication Date: May. 10, 2019
- Vol. 17, Issue 5, 051201 (2019)
A miniaturized system for measurement of the refractive index of sub-microliter liquid|Editors' Pick
Minghui Chen, Wenyu Jia, Jintao He, Martial Geiser, and Gang Zheng
This study introduced the research and development of a portable and miniaturized system for the measurement of the refractive index of sub-microliter liquid based on a microfluidic chip. A technical method of double-beam interference, was proposed for use in the measurement. Based on this, by using a laser diode as a light source, changes in the refractive index were calculated by utilizing a complementary metal–oxide–semiconductor to detect the movement of interference fringes of the liquid. Firstly, this study simulated the effects of influencing factors on the interference infringes of two Gaussian beams, such as their spot sizes, distance between two beam spots, and detection range. Secondly, this research introduced the system design and construction of the double-beam interference method and analyzed the results of refractive index tests on sub-microliter aqueous glucose solutions with different concentrations. The measurement accuracy reached 10 4 refractive index units. This system has a compact structure and is rendered portable by using batteries for its power supply. The entire system is designed to be a double Z-shaped structure with a length of about 15 cm, a width of 5 cm, and a height of about 10 cm. It can be used to measure changes in the refractive index of sub-microliter to nanoliter liquids based on the use of a microfluidic chip. This study introduced the research and development of a portable and miniaturized system for the measurement of the refractive index of sub-microliter liquid based on a microfluidic chip. A technical method of double-beam interference, was proposed for use in the measurement. Based on this, by using a laser diode as a light source, changes in the refractive index were calculated by utilizing a complementary metal–oxide–semiconductor to detect the movement of interference fringes of the liquid. Firstly, this study simulated the effects of influencing factors on the interference infringes of two Gaussian beams, such as their spot sizes, distance between two beam spots, and detection range. Secondly, this research introduced the system design and construction of the double-beam interference method and analyzed the results of refractive index tests on sub-microliter aqueous glucose solutions with different concentrations. The measurement accuracy reached 10 4 refractive index units. This system has a compact structure and is rendered portable by using batteries for its power supply. The entire system is designed to be a double Z-shaped structure with a length of about 15 cm, a width of 5 cm, and a height of about 10 cm. It can be used to measure changes in the refractive index of sub-microliter to nanoliter liquids based on the use of a microfluidic chip.
Chinese Optics Letters
- Publication Date: Apr. 10, 2019
- Vol. 17, Issue 4, 041201 (2019)
Participation in the absolute gravity comparison with a compact cold atom gravimeter|On the Cover
Zhijie Fu, Qiyu Wang, Zhaoying Wang, Bin Wu, Bing Cheng, and Qiang Lin
The first Asia-Pacific Comparison of Absolute Gravimeters (APMP.M.G-K1) was organized by the National Institute of Metrology (NIM) of China from December 21, 2015 to March 25, 2016 in Changping, Beijing. Our compact cold atom gravimeter (CCAG) was transported from Hangzhou to Beijing with a long distance of about 1200 km to participate in this comparison. The CCAG is the only one, to the best of our knowledge, that is based on the principle of atom interferometry among all the instruments. Absolute gravity in the indicated three test sites has been measured as requested by the organizer. The sensitivity of our CCAG is estimated to be 90 μGal/Hz, even when the measurements are carried out without any vibration isolation. Besides, the accuracy of this gravimeter has been evaluated to be about 19 μGal by considering the significant system errors. Our results show a good agreement with the given reference value. The first Asia-Pacific Comparison of Absolute Gravimeters (APMP.M.G-K1) was organized by the National Institute of Metrology (NIM) of China from December 21, 2015 to March 25, 2016 in Changping, Beijing. Our compact cold atom gravimeter (CCAG) was transported from Hangzhou to Beijing with a long distance of about 1200 km to participate in this comparison. The CCAG is the only one, to the best of our knowledge, that is based on the principle of atom interferometry among all the instruments. Absolute gravity in the indicated three test sites has been measured as requested by the organizer. The sensitivity of our CCAG is estimated to be 90 μGal/Hz, even when the measurements are carried out without any vibration isolation. Besides, the accuracy of this gravimeter has been evaluated to be about 19 μGal by considering the significant system errors. Our results show a good agreement with the given reference value.
Chinese Optics Letters
- Publication Date: Jan. 10, 2019
- Vol. 17, Issue 1, 011204 (2019)
Method for simultaneously and directly measuring all six-DOF motion errors of a rotary axis
Jiakun Li, Qibo Feng, Chuanchen Bao, and Bin Zhang
We report a method for simultaneously and directly measuring all six-degrees-of-freedom (six-DOF) motion errors of a rotary axis. Such a method combines the principles of laser interferometry and laser collimation measurement. One reference rotary axis and two retro-reflectors are used to achieve simultaneous sensitivity to all six errors in a full-circle measuring range. As no separation models are required, our method is capable of dynamically measuring these errors in real time and conveniently determining the origin of the errors. An automatic measuring device is built. The effectiveness of our method is experimentally demonstrated. We report a method for simultaneously and directly measuring all six-degrees-of-freedom (six-DOF) motion errors of a rotary axis. Such a method combines the principles of laser interferometry and laser collimation measurement. One reference rotary axis and two retro-reflectors are used to achieve simultaneous sensitivity to all six errors in a full-circle measuring range. As no separation models are required, our method is capable of dynamically measuring these errors in real time and conveniently determining the origin of the errors. An automatic measuring device is built. The effectiveness of our method is experimentally demonstrated.
Chinese Optics Letters
- Publication Date: Jan. 10, 2019
- Vol. 17, Issue 1, 011203 (2019)
Double-pass grating imaging spectrometer
Xin Meng, Zhongming Yang, Jinyu Du, and Guobin Fan
A double-pass grating imaging spectrometer is proposed and demonstrated. The traditional entrance slit is replaced by a middle reflective slit, which is used as a spectral filter rather than a spatial filter. The light from the scene passes through the same dispersive grating twice. The full image of the scene can be obtained with a snapshot. Therefore, the stripe noise and image distortion caused by image mosaicking can be eliminated. Besides, the target is easier to be captured and focused, just like using a camera. This method can be used to obtain clearer spectral images of the scene conveniently and quickly. A double-pass grating imaging spectrometer is proposed and demonstrated. The traditional entrance slit is replaced by a middle reflective slit, which is used as a spectral filter rather than a spatial filter. The light from the scene passes through the same dispersive grating twice. The full image of the scene can be obtained with a snapshot. Therefore, the stripe noise and image distortion caused by image mosaicking can be eliminated. Besides, the target is easier to be captured and focused, just like using a camera. This method can be used to obtain clearer spectral images of the scene conveniently and quickly.
Chinese Optics Letters
- Publication Date: Jan. 10, 2019
- Vol. 17, Issue 1, 011202 (2019)
Imaging method of single layer graphene on metal substrate based on imaging ellipsometer with large field of view
Guiyun Li, Liyuan Gu, Jingpei Hu, Linglin Zhu, Aijun Zeng, and Huijie Huang
Single layer lattice graphene deposited on the metal substrate can hardly be imaged by the optical microscope. In this Letter, a large field-of-view imaging ellipsometer is introduced to image single layer graphene which is deposited on a metal substrate. By adjusting the polarizer and the analyzer of imaging ellipsometer, the light reflected from surfaces of either single layer graphene or a Au film substrate can be extinguished, respectively. Thus, single layer graphene can be imaged correspondingly under brightfield or darkfield imaging modes. The method can be applied to imaging large-area graphene on a metal substrate. Single layer lattice graphene deposited on the metal substrate can hardly be imaged by the optical microscope. In this Letter, a large field-of-view imaging ellipsometer is introduced to image single layer graphene which is deposited on a metal substrate. By adjusting the polarizer and the analyzer of imaging ellipsometer, the light reflected from surfaces of either single layer graphene or a Au film substrate can be extinguished, respectively. Thus, single layer graphene can be imaged correspondingly under brightfield or darkfield imaging modes. The method can be applied to imaging large-area graphene on a metal substrate.
Chinese Optics Letters
- Publication Date: Jan. 10, 2019
- Vol. 17, Issue 1, 011201 (2019)
Model-based adaptive non-null interferometry for freeform surface metrology
Lei Zhang, Sheng Zhou, Dong Li, Jingsong Li, and Benli Yu
A model-based adaptive non-null interferometry (MANI) is proposed for steep optical freeform surfaces in situ testing. The deformable mirror (DM) affording the flexible compensation is monitored with the beam in the interferometer by a wavefront sensor. The residual wavefront aberration in the non-null interferogram is eliminated by the multi-configuration ray tracing algorithm based on the system model, especially the DM surface model. The final figure error can be extracted together with the surface misalignment aberration correction. Experiments proving the feasibility of the MANI are shown. A model-based adaptive non-null interferometry (MANI) is proposed for steep optical freeform surfaces in situ testing. The deformable mirror (DM) affording the flexible compensation is monitored with the beam in the interferometer by a wavefront sensor. The residual wavefront aberration in the non-null interferogram is eliminated by the multi-configuration ray tracing algorithm based on the system model, especially the DM surface model. The final figure error can be extracted together with the surface misalignment aberration correction. Experiments proving the feasibility of the MANI are shown.
Chinese Optics Letters
- Publication Date: Aug. 10, 2018
- Vol. 16, Issue 8, 081203 (2018)
Experimental realization of a switchable filter based on a dynamically transformable array
Xin Chen, Jinsong Gao, and Bonan Kang
We introduce a geometrically reconfigurable metasurface whose artificial “atoms” will reorient within unit cells in response to a thermal stimulus in the microwave spectrum. It can alternate between two contrasting behaviors under different temperatures and serve as a switchable filter that allows the incident energy to be selectively transmitted or reflected with an excess of 10 dB isolation at certain frequencies for both polarizations. The experimental results are consistent with the theoretical simulations, verifying the availability of an innovative method for manipulating electromagnetic waves with the merits of higher controllability for dynamic behavior and greater flexibility in the design process. We introduce a geometrically reconfigurable metasurface whose artificial “atoms” will reorient within unit cells in response to a thermal stimulus in the microwave spectrum. It can alternate between two contrasting behaviors under different temperatures and serve as a switchable filter that allows the incident energy to be selectively transmitted or reflected with an excess of 10 dB isolation at certain frequencies for both polarizations. The experimental results are consistent with the theoretical simulations, verifying the availability of an innovative method for manipulating electromagnetic waves with the merits of higher controllability for dynamic behavior and greater flexibility in the design process.
Chinese Optics Letters
- Publication Date: Aug. 10, 2018
- Vol. 16, Issue 8, 081202 (2018)
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