sensors-logo

Journal Browser

Journal Browser

Important Achievements in Optical Measurements in China 2022–2023

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Optical Sensors".

Deadline for manuscript submissions: closed (15 February 2024) | Viewed by 26474

Special Issue Editors


E-Mail Website
Guest Editor
National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150001, China
Interests: gas sensor; optical sensor; laser spectroscopy based sensor; optical sensor applications
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Hefei Institutes of Physical Sciences, Chinese Academy of Sciences (CAS), Hefei 230031, China
Interests: environmental pollution monitoring with spectroscopy; laser spectroscopy; optical environment remote sensing

E-Mail Website
Guest Editor
Key Laboratory of Advanced Transducers and Intelligent Control System, Ministry of Education, College of Physics and Optoelectronic Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Interests: quantum precision measurement; single molecule spectroscopy; photon communication

E-Mail Website
Guest Editor
School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China
Interests: laser interferometry; LIDAR; infrared imaging and detection; computational imaging
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy Sciences, Xi’an 710119, China
Interests: super-resolution and 3D optical microscopy; quantitative phase imaging; optical trapping and manipulation
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Optical measurement techniques are used for the online measurement of physical, chemical, medical, and biological quantities. As powerful techniques, they have been widely adopted in many fields and cover a broad range of applications, including atmospheric chemistry, environmental monitoring, industrial emission, life sciences and medicine, etc. In recent years, optical measurement techniques have experienced rapid development due to the emergence and maturity of device physics such as light sources and detection strategies. The most prominent feature of optical measurement techniques is their noncontact, high precision and high speed because of the related characteristics of light.

This Special Issue plans to propose a collection of high-quality research papers focused on state-of-the-art optical measurement techniques, also encouraging review articles. Potential topics include, but are not limited to, the following:

  • Optical sensing;
  • Optical imaging;
  • Optical diagnostics;
  • Optical lidar;
  • Optical sources;
  • Optical detectors.

Prof. Dr. Yufei Ma
Prof. Dr. Jianguo Liu
Prof. Dr. Liantuan Xiao
Prof. Dr. Qun Hao
Prof. Dr. Baoli Yao
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (16 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Jump to: Review

14 pages, 3665 KiB  
Article
Decoupling and Parameter Extraction Methods for Conical Micro-Motion Object Based on FMCW Lidar
by Zhen Yang, Yufan Yang, Manguo Liu, Yuan Wei, Yong Zhang, Jianlong Zhang, Xue Liu and Xin Dai
Sensors 2024, 24(6), 1832; https://doi.org/10.3390/s24061832 - 13 Mar 2024
Viewed by 429
Abstract
Micro-Doppler time–frequency analysis has been regarded as an important parameter extraction method for conical micro-motion objects. However, the micro-Doppler effect caused by micro-motion can modulate the frequency of lidar echo, leading to coupling between structure and micro-motion parameters. Therefore, it is difficult to [...] Read more.
Micro-Doppler time–frequency analysis has been regarded as an important parameter extraction method for conical micro-motion objects. However, the micro-Doppler effect caused by micro-motion can modulate the frequency of lidar echo, leading to coupling between structure and micro-motion parameters. Therefore, it is difficult to extract parameters for micro-motion cones. We propose a new method for parameter extraction by combining the range profile of a micro-motion cone and the micro-Doppler time–frequency spectrum. This method can effectively decouple and accurately extract the structure and the micro-motion parameters of cones. Compared with traditional time–frequency analysis methods, the accuracy of parameter extraction is higher, and the information is richer. Firstly, the range profile of the micro-motion cone was obtained by using an FMCW (Frequency Modulated Continuous Wave) lidar based on simulation. Secondly, quantitative analysis was conducted on the edge features of the range profile and the micro-Doppler time–frequency spectrum. Finally, the parameters of the micro-motion cone were extracted based on the proposed decoupling parameter extraction method. The results show that our method can effectively extract the cone height, the base radius, the precession angle, the spin frequency, and the gravity center height within the range of a lidar LOS (line of sight) angle from 20° to 65°. The average absolute percentage error can reach below 10%. The method proposed in this paper not only enriches the detection information regarding micro-motion cones, but also improves the accuracy of parameter extraction and establishes a foundation for classification and recognition. It provides a new technical approach for laser micro-Doppler detection in accurate recognition. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

17 pages, 8373 KiB  
Article
CEEMDAN-LWT De-Noising Method for Pipe-Jacking Inertial Guidance System Based on Fiber Optic Gyroscope
by Yutong Zu, Lu Wang, Yuanbiao Hu and Gansheng Yang
Sensors 2024, 24(4), 1097; https://doi.org/10.3390/s24041097 - 07 Feb 2024
Viewed by 488
Abstract
An inertial guidance system based on a fiber optic gyroscope (FOG) is an effective way to guide long-distance curved pipe jacking. However, environmental disturbances such as vibration, electromagnetism, and temperature will cause the FOG signal to generate significant random noise. The random noise [...] Read more.
An inertial guidance system based on a fiber optic gyroscope (FOG) is an effective way to guide long-distance curved pipe jacking. However, environmental disturbances such as vibration, electromagnetism, and temperature will cause the FOG signal to generate significant random noise. The random noise will overwhelm the effective signal. Therefore, it is necessary to eliminate the random noise. This study proposes a hybrid de-noising method, namely complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN)—lifting wavelet transform (LWT). Firstly, the FOG signal is extracted using a sliding window and decomposed by CEEMDAN to obtain the intrinsic modal function (IMF) with N different scales and one residual. Subsequently, the effective IMF components are selected according to the correlation coefficient between the IMF components and the FOG signal. Due to the low resolution of the CEEMDAN method for high-frequency components, the selected high-frequency IMF components are decomposed with lifting wavelet transform to increase the resolution of the signal. The detailed signals of the LWT decomposition are de-noised using the soft threshold de-noising method, and then the signal is reconstructed. Finally, pipe-jacking dynamic and environmental interference experiments were conducted to verify the effectiveness of the CEEMDAN-LWT de-noising method. The de-noising effect of the proposed method was evaluated by SNR, RMSE, and Deviation and compared with the CEEMDAN and LWT de-noising methods. The results show that the CEEMDAN-LWT de-noising method has the best de-noising effect with good adaptivity and high accuracy. The navigation results of the pipe-jacking attitude before and after de-noising were compared and analyzed in the environmental interference experiment. The results show that the absolute error of the pipe-jacking pitch, roll, and heading angles is reduced by 39.86%, 59.45%, and 14.29% after de-noising. The maximum relative error of the pitch angle is improved from −0.74% to −0.44%, the roll angle is improved from 2.07% to 0.79%, and the heading angle is improved from −0.07% to −0.06%. Therefore, the CEEMDAN-LWT method can effectively suppress the random errors of the FOG signal caused by the environment and improve the measurement accuracy of the pipe-jacking attitude. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

16 pages, 5695 KiB  
Article
Design of Optical System for Ultra-Large Range Line-Sweep Spectral Confocal Displacement Sensor
by Weiguang Yang, Jian Du, Meijie Qi, Jiayue Yan, Mohan Cheng and Zhoufeng Zhang
Sensors 2024, 24(3), 723; https://doi.org/10.3390/s24030723 - 23 Jan 2024
Viewed by 798
Abstract
The spectrum confocal displacement sensor is an innovative type of photoelectric sensor. The non-contact advantages of this method include the capacity to obtain highly accurate measurements without inflicting any harm as well as the ability to determine the object’s surface contour recovery by [...] Read more.
The spectrum confocal displacement sensor is an innovative type of photoelectric sensor. The non-contact advantages of this method include the capacity to obtain highly accurate measurements without inflicting any harm as well as the ability to determine the object’s surface contour recovery by reconstructing the measurement data. Consequently, it has been widely used in the field of three-dimensional topographic measuring. The spectral confocal displacement sensor consists of a light source, a dispersive objective, and an imaging spectrometer. The scanning mode can be categorized into point scanning and line scanning. Point scanning is inherently present when the scanning efficiency is low, resulting in a slower measurement speed. Further improvements are necessary in the research on the line-scanning type. It is crucial to expand the measurement range of existing studies to overcome the limitations encountered during the detection process. The objective of this study is to overcome the constraints of the existing line-swept spectral confocal displacement sensor’s limited measuring range and lack of theoretical foundation for the entire system. This is accomplished by suggesting an appropriate approach for creating the optical design of the dispersive objective lens in the line-swept spectral confocal displacement sensor. Additionally, prism-grating beam splitting is employed to simulate and analyze the imaging spectrometer’s back end. The combination of a prism and a grating eliminates the spectral line bending that occurs in the imaging spectrometer. The results indicate that a complete optical pathway for the line-scanning spectral confocal displacement sensor has been built, achieving an axial resolution of 0.8 μm, a scanning line length of 24 mm, and a dispersion range of 3.9 mm. This sensor significantly expands the range of measurements and fills a previously unaddressed gap in the field of analyzing the current stage of line-scanning spectral confocal displacement sensors. This is a groundbreaking achievement for both the sensor itself and the field it operates in. The line-scanning spectral confocal displacement sensor’s design addresses a previously unmet need in systematic analysis by successfully obtaining a wide measuring range. This provides systematic theoretical backing for the advancement of the sensor, which has potential applications in the industrial detection of various ranges and complicated objects. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

19 pages, 5880 KiB  
Article
A Mid-Infrared Quantum Cascade Laser Ultra-Sensitive Trace Formaldehyde Detection System Based on Improved Dual-Incidence Multipass Gas Cell
by Tao Wu, Renzhi Hu, Pinhua Xie, Lijie Zhang, Changjin Hu, Xiaoyan Liu, Jiawei Wang, Liujun Zhong, Jinzhao Tong and Wenqing Liu
Sensors 2023, 23(12), 5643; https://doi.org/10.3390/s23125643 - 16 Jun 2023
Viewed by 1112
Abstract
Formaldehyde (HCHO) is a tracer of volatile organic compounds (VOCs), and its concentration has gradually decreased with the reduction in VOC emissions in recent years, which puts forward higher requirements for the detection of trace HCHO. Therefore, a quantum cascade laser (QCL) with [...] Read more.
Formaldehyde (HCHO) is a tracer of volatile organic compounds (VOCs), and its concentration has gradually decreased with the reduction in VOC emissions in recent years, which puts forward higher requirements for the detection of trace HCHO. Therefore, a quantum cascade laser (QCL) with a central excitation wavelength of 5.68 μm was applied to detect the trace HCHO under an effective absorption optical pathlength of 67 m. An improved, dual-incidence multi-pass cell, with a simple structure and easy adjustment, was designed to further improve the absorption optical pathlength of the gas. The instrument detection sensitivity of 28 pptv (1σ) was achieved within a 40 s response time. The experimental results show that the developed HCHO detection system is almost unaffected by the cross interference of common atmospheric gases and the change of ambient humidity. Additionally, the instrument was successfully deployed in a field campaign, and it delivered results that correlated well with those of a commercial instrument based on continuous wave cavity ring-down spectroscopy (R2 = 0.967), which indicates that the instrument has a good ability to monitor ambient trace HCHO in unattended continuous operation for long periods of time. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

18 pages, 4965 KiB  
Article
Shape Discrimination of Individual Aerosol Particles Using Light Scattering
by Yan Han, Lei Ding, Yingping Wang, Haiyang Zheng and Li Fang
Sensors 2023, 23(12), 5464; https://doi.org/10.3390/s23125464 - 09 Jun 2023
Viewed by 1107
Abstract
We established an experimental apparatus by combining polarized light scattering and angle-resolved light scattering measurement technology to rapidly identify the shape of an individual aerosol particle. The experimental data of scattered light of Oleic acid, rod-shaped Silicon dioxide, and other particles with typical [...] Read more.
We established an experimental apparatus by combining polarized light scattering and angle-resolved light scattering measurement technology to rapidly identify the shape of an individual aerosol particle. The experimental data of scattered light of Oleic acid, rod-shaped Silicon dioxide, and other particles with typical shape characteristics were analyzed statistically. To better study the relationship between the shape of particles and the properties of scattered light, the partial least squares discriminant analysis (PLS-DA) method was used to analyze the scattered light of aerosol samples based on the size screening of particles, and the shape recognition and classification method of the individual aerosol particle was established based on the analysis of the spectral data after nonlinear processing and grouping by particle size with the area under the receiver operating characteristic curve (AUC) as reference. The experimental results show that the proposed classification method has a good discrimination ability for spherical, rod-shaped, and other non-spherical particles, which can provide more information for atmospheric aerosol measurement, and has application value for traceability and exposure hazard assessment of aerosol particles. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

11 pages, 2543 KiB  
Communication
Methods for Comprehensive Calibration of a Low-Frequency Angular Acceleration Rotary Table
by Renjian Feng, Jiaxuan Yan, Yinfeng Wu, Ning Yu and Xudong Yin
Sensors 2023, 23(10), 4876; https://doi.org/10.3390/s23104876 - 18 May 2023
Viewed by 1018
Abstract
The total harmonic distortion (THD) index and its calculation methods are presented to calibrate the sinusoidal motion of the low-frequency angular acceleration rotary table (LFAART) and make up the incomprehensive evaluation based on the angular acceleration amplitude and frequency error indexes. The THD [...] Read more.
The total harmonic distortion (THD) index and its calculation methods are presented to calibrate the sinusoidal motion of the low-frequency angular acceleration rotary table (LFAART) and make up the incomprehensive evaluation based on the angular acceleration amplitude and frequency error indexes. The THD is calculated from two measurement schemes: a unique scheme combining the optical shaft encoder and the laser triangulation sensor and a regular scheme using the fiber optical gyroscope (FOG). An improved reversing moments recognition method is presented to upgrade the accuracy of solving the angular motion amplitude based on optical shaft encoder output. The field experiment shows that the difference in the THD values achieved using the combining scheme and FOG is within 0.11% when the signal-to-noise ratio of the FOG signal is higher than 7.7 dB, indicating the accuracy of the proposed methods and the feasibility of taking THD as the index. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

13 pages, 4222 KiB  
Article
A Miniaturized 3D-Printed Quartz-Enhanced Photoacoustic Spectroscopy Sensor for Methane Detection with a High-Power Diode Laser
by Yanjun Chen, Tiantian Liang, Shunda Qiao and Yufei Ma
Sensors 2023, 23(8), 4034; https://doi.org/10.3390/s23084034 - 17 Apr 2023
Cited by 4 | Viewed by 1496
Abstract
In this invited paper, a highly sensitive methane (CH4) trace gas sensor based on quartz-enhanced photoacoustic spectroscopy (QEPAS) technique using a high-power diode laser and a miniaturized 3D-printed acoustic detection unit (ADU) is demonstrated for the first time. A high-power diode [...] Read more.
In this invited paper, a highly sensitive methane (CH4) trace gas sensor based on quartz-enhanced photoacoustic spectroscopy (QEPAS) technique using a high-power diode laser and a miniaturized 3D-printed acoustic detection unit (ADU) is demonstrated for the first time. A high-power diode laser emitting at 6057.10 cm−1 (1650.96 nm), with the optical power up to 38 mW, was selected as the excitation source to provide a strong excitation. A 3D-printed ADU, including the optical and photoacoustic detection elements, had a dimension of 42 mm, 27 mm, and 8 mm in length, width, and height, respectively. The total weight of this 3D-printed ADU, including all elements, was 6 g. A quartz tuning fork (QTF) with a resonant frequency and Q factor of 32.749 kHz and 10,598, respectively, was used as an acoustic transducer. The performance of the high-power diode laser-based CH4–QEPAS sensor, with 3D-printed ADU, was investigated in detail. The optimum laser wavelength modulation depth was found to be 0.302 cm−1. The concentration response of this CH4–QEPAS sensor was researched when the CH4 gas sample, with different concentration samples, was adopted. The obtained results showed that this CH4–QEPAS sensor had an outstanding linear concentration response. The minimum detection limit (MDL) was found to be 14.93 ppm. The normalized noise equivalent absorption (NNEA) coefficient was obtained as 2.20 × 10−7 cm−1W/Hz−1/2. A highly sensitive CH4–QEPAS sensor, with a small volume and light weight of ADU, is advantageous for the real applications. It can be portable and carried on some platforms, such as an unmanned aerial vehicle (UAV) and a balloon. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

18 pages, 6442 KiB  
Article
Bayesian-Based Hybrid Method for Rapid Optimization of NV Center Sensors
by Jiazhao Tian, Ressa S. Said, Fedor Jelezko, Jianming Cai and Liantuan Xiao
Sensors 2023, 23(6), 3244; https://doi.org/10.3390/s23063244 - 19 Mar 2023
Cited by 2 | Viewed by 1517
Abstract
NV centers are among the most promising platforms in the field of quantum sensing. Magnetometry based on NV centers, especially, has achieved concrete development in areas of biomedicine and medical diagnostics. Improving the sensitivity of NV center sensors under wide inhomogeneous broadening and [...] Read more.
NV centers are among the most promising platforms in the field of quantum sensing. Magnetometry based on NV centers, especially, has achieved concrete development in areas of biomedicine and medical diagnostics. Improving the sensitivity of NV center sensors under wide inhomogeneous broadening and fieldamplitude drift is a crucial issue of continuous concern that relies on the coherent control of NV centers with high average fidelity. Quantum optimal control (QOC) methods provide access to this target; nevertheless, the high time consumption of current methods due to the large number of needful sample points as well as the complexity of the parameter space has hindered their usability. In this paper, we propose the Bayesian estimation phase-modulated (B-PM) method to tackle this problem. In the case of the state transforming of an NV center ensemble, the B-PM method reduced the time consumption by more than 90% compared with the conventional standard Fourier basis (SFB) method while increasing the average fidelity from 0.894 to 0.905. In the AC magnetometry scenario, the optimized control pulse obtained with the B-PM method achieved an eight-fold extension of coherence time T2 compared with the rectangular π pulse. Similar application can be made in other sensing situations. As a general algorithm, the B-PM method can be further extended to the open- and closed-loop optimization of complex systems based on a variety of quantum platforms. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

11 pages, 4638 KiB  
Article
Fiber Residual Stress Effects on Modal Gain Equalization of Few-Mode Fiber Amplifier
by Li Pei, Yanbiao Chang, Jianshuai Wang, Jingjing Zheng, Tigang Ning, Jing Li, Bing Bai, Lei Shen and Li Zhong
Sensors 2023, 23(5), 2574; https://doi.org/10.3390/s23052574 - 25 Feb 2023
Cited by 2 | Viewed by 1388
Abstract
The modal gain equalization (MGE) of few-mode fiber amplifiers (FMFAs) ensures the stability of signal transmission. MGE mainly relies on the multi-step refractive index (RI) and doping profile of few-mode erbium-doped fibers (FM-EDFs). However, complex RI and doping profiles lead to uncontrollable residual [...] Read more.
The modal gain equalization (MGE) of few-mode fiber amplifiers (FMFAs) ensures the stability of signal transmission. MGE mainly relies on the multi-step refractive index (RI) and doping profile of few-mode erbium-doped fibers (FM-EDFs). However, complex RI and doping profiles lead to uncontrollable residual stress variations in fiber fabrication. Variable residual stress apparently affects MGE due to its impacts on the RI. So, this paper focuses on the residual stress effects on MGE. The residual stress distributions of passive and active FMFs were measured using a self-constructed residual stress test configuration. As the erbium doping concentration increased, the residual stress of the fiber core decreased, and the residual stress of the active fibers was two orders of magnitude lower than that of the passive fiber. Compared with the passive FMF and the FM-EDFs, the residual stress of the fiber core completely transformed from tensile stress to compressive stress. This transformation led to an obvious smooth RI curve variation. The measurement values were analyzed with FMFA theory, and the results show that the differential modal gain of the FMFA increased from 0.96 to 1.67 dB as the residual stress decreased from 4.86 to 0.01 MPa. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

10 pages, 3061 KiB  
Article
The Development of a Novel Headspace O2 Concentration Measurement Sensor for Vials
by Xiao Chen, Hao Sun, Wei Huang, Jiayi Jin, Mingxu Su and Huinan Yang
Sensors 2023, 23(5), 2438; https://doi.org/10.3390/s23052438 - 22 Feb 2023
Viewed by 1705
Abstract
In the process of manufacture and transportation, vials are prone to breakage and cracks. Oxygen (O2) in the air entering vials can lead to the deterioration of medicine and a reduction in pesticide effects, threatening the life of patients. Therefore, accurate [...] Read more.
In the process of manufacture and transportation, vials are prone to breakage and cracks. Oxygen (O2) in the air entering vials can lead to the deterioration of medicine and a reduction in pesticide effects, threatening the life of patients. Therefore, accurate measurement of the headspace O2 concentration for vials is crucial to ensure pharmaceutical quality. In this invited paper, a novel headspace oxygen concentration measurement (HOCM) sensor for vials was developed based on tunable diode laser absorption spectroscopy (TDLAS). First, a long–optical–path multi–pass cell was designed by optimizing the original system. Moreover, vials with different O2 concentrations (0%, 5%, 10%, 15%, 20%, and 25%) were measured with this optimized system in order to study the relationship between the leakage coefficient and O2 concentration; the root mean square error of the fitting was 0.13. Moreover, the measurement accuracy indicates that the novel HOCM sensor achieved an average percentage error of 1.9%. Sealed vials with different leakage holes (4, 6, 8, and 10 mm) were prepared to investigate the variation in the headspace O2 concentration with time. The results show that the novel HOCM sensor is non-invasive and has a fast response and high accuracy, with prospects in applications for online quality supervision and management of production lines. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

15 pages, 5901 KiB  
Article
Real-Time Compensation for SLD Light-Power Fluctuation in an Interferometric Fiber-Optic Gyroscope
by Shijie Zheng, Mengyu Ren, Xin Luo, Hangyu Zhang and Guoying Feng
Sensors 2023, 23(4), 1925; https://doi.org/10.3390/s23041925 - 08 Feb 2023
Cited by 1 | Viewed by 1741
Abstract
An interferometric fiber-optic gyroscope (IFOG) demodulates a rotation signal via interferometric light intensity. However, the working environments of IFOGs typically involve great uncertainty. Fluctuations in temperature, air pressure, electromagnetic field, and the power system all cause the power of the superluminescent diode (SLD) [...] Read more.
An interferometric fiber-optic gyroscope (IFOG) demodulates a rotation signal via interferometric light intensity. However, the working environments of IFOGs typically involve great uncertainty. Fluctuations in temperature, air pressure, electromagnetic field, and the power system all cause the power of the superluminescent diode (SLD) light source to fluctuate as well. In this invited paper, we studied the effects of SLD power fluctuation on the dynamic and static performance characteristics of a gyro system through the use of a light-power feedback loop. Fluctuations of 0.5 mA, 1 mA, and 5 mA in the SLD source entering the IFOG caused zero-bias stability to be 69, 135, and 679 times worse. We established an effective method to monitor power fluctuations of SLD light sources and to compensate for their effects without increasing hardware complexity or system cost. In brief, we established a real-time power-sensing and -compensating system. Experimental results showed that for every 0.1 mA increase in the fluctuation amplitude of the driving current, the zero-bias stability became 4 to 7 times worse, which could be reduced about 95% through the use of SLD power compensation. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

14 pages, 3829 KiB  
Article
Performance Characterization of a Fully Transportable Mid-Infrared Laser Heterodyne Radiometer (LHR)
by Fengjiao Shen, Xueyou Hu, Jun Lu, Zhengyue Xue, Jun Li, Tu Tan, Zhensong Cao, Xiaoming Gao and Weidong Chen
Sensors 2023, 23(2), 978; https://doi.org/10.3390/s23020978 - 14 Jan 2023
Viewed by 1321
Abstract
A fully transportable laser heterodyne radiometer (LHR), involving a flexible polycrystalline mid-infrared (PIR) fiber-coupling system and operating around 8 µm, was characterized and optimized with the help of a calibrated high temperature blackbody source to simulate solar radiation. Compared to a mid-IR free-space [...] Read more.
A fully transportable laser heterodyne radiometer (LHR), involving a flexible polycrystalline mid-infrared (PIR) fiber-coupling system and operating around 8 µm, was characterized and optimized with the help of a calibrated high temperature blackbody source to simulate solar radiation. Compared to a mid-IR free-space sunlight coupling system, usually used in a current LHR, such a fiber-coupling system configuration makes the mid-infrared (MIR) LHR fully transportable. The noise sources, heterodyne signal, and SNR of the MIR LHR were analyzed, and the optimum operating local oscillator (LO) photocurrent was experimentally obtained. The spectroscopic performance of the MIR LHR was finally evaluated. This work demonstrated that the developed fully transportable MIR LHR could be used for ground-based atmospheric sounding measurements of multiple trace gases in the atmospheric column. In addition, it also has high potential for applications on spacecraft or on an airborne platform. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

12 pages, 10155 KiB  
Article
Pre-Shaped Burst-Mode Hybrid MOPA Laser System at 10 kHz Pulse Frequency
by Shanchun Zhang, Xin Yu, Jiangbo Peng and Zhen Cao
Sensors 2023, 23(2), 834; https://doi.org/10.3390/s23020834 - 11 Jan 2023
Viewed by 1509
Abstract
A temporal pre-shaped burst-mode hybrid fiber-bulk laser system was illustrated at a 10 kHz rate with a narrow spectral linewidth. A theoretical model was proposed to counteract the temporal profile distortion and compensate for the desired one, based on reverse process of amplification. [...] Read more.
A temporal pre-shaped burst-mode hybrid fiber-bulk laser system was illustrated at a 10 kHz rate with a narrow spectral linewidth. A theoretical model was proposed to counteract the temporal profile distortion and compensate for the desired one, based on reverse process of amplification. For uniformly modulated injection, amplified shapes were recorded and investigated in series for their varied pulse duration, envelope width and amplification delay, respectively. The pre-shaped output effectively realized a uniform distribution on a time scale for both the burst envelope and pulse shape under the action of the established theoretical method. Compared with previous amplification delay methods, this model possesses the capacity to extend itself for applications in burst-mode shaping with variable parameters and characteristics. The maximum pulse energy was enlarged up to 9.68 mJ, 8.94 mJ and 6.57 mJ with a 300 ns pulse duration over envelope widths of 2 ms to 4 ms. Moreover, the time-averaged spectral bandwidths were measured and characterized with Lonrentz fits of 68.3 MHz, 67.2 MHz and 67.7 MHz when the pulse duration varied from 100 ns to 300 ns. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

8 pages, 2468 KiB  
Communication
Wedged Fiber Optic Surface Plasmon Resonance Sensor for High-Sensitivity Refractive Index and Temperature Measurements
by Lixia Li, Yuli Li, Xueyang Zong, Linlin Zhao, Penglei Li, Kun Yu and Yufang Liu
Sensors 2022, 22(23), 9099; https://doi.org/10.3390/s22239099 - 23 Nov 2022
Cited by 2 | Viewed by 4546
Abstract
Here, we experimentally demonstrate a wedged fiber optic surface plasmon resonance (SPR) sensor enabling high-sensitivity temperature detection. The sensing probe has a geometry with two asymmetrical bevels, with one inclined surface coated with an optically thin film supporting propagating plasmons and the other [...] Read more.
Here, we experimentally demonstrate a wedged fiber optic surface plasmon resonance (SPR) sensor enabling high-sensitivity temperature detection. The sensing probe has a geometry with two asymmetrical bevels, with one inclined surface coated with an optically thin film supporting propagating plasmons and the other coated with a reflecting metal film. The angle of incident light can be readily tuned through modifying the beveled angles of the fiber tip, which has a remarkable impact on the refractive index sensitivity of SPR sensors. As a result, we measure a high refractive index sensitivity as large as 8161 nm/RIU in a wide refractive index range of 1.333–1.404 for the optimized sensor. Furthermore, we carry out a temperature-sensitivity measurement by packaging the SPR probe into a capillary filled with n-butanol. This showed a temperature sensitivity reaching up to −3.35 nm/°C in a wide temperature range of 20 °C–100 °C. These experimental results are well in agreement with those obtained from simulations, thus suggesting that our work may be of significance in designing reflective fiber optic SPR sensing probes with modified geometries. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

Review

Jump to: Research

24 pages, 3517 KiB  
Review
Development of a 2 μm Solid-State Laser for Lidar in the Past Decade
by Kuan Li, Chao Niu, Chunting Wu, Yongji Yu and Yao Ma
Sensors 2023, 23(16), 7024; https://doi.org/10.3390/s23167024 - 08 Aug 2023
Cited by 4 | Viewed by 1119
Abstract
The 2 μm wavelength belongs to the eye-safe band and has a wide range of applications in the fields of lidar, biomedicine, and materials processing. With the rapid development of military, wind power, sensing, and other industries, new requirements for 2 μm solid-state [...] Read more.
The 2 μm wavelength belongs to the eye-safe band and has a wide range of applications in the fields of lidar, biomedicine, and materials processing. With the rapid development of military, wind power, sensing, and other industries, new requirements for 2 μm solid-state laser light sources have emerged, especially in the field of lidar. This paper focuses on the research progress of 2 μm solid-state lasers for lidar over the past decade. The technology and performance of 2 μm pulsed single longitudinal mode solid-state lasers, 2 μm seed solid-state lasers, and 2 μm high power solid-state lasers are, respectively, summarized and analyzed. This paper also introduces the properties of gain media commonly used in the 2 μm band, the construction method of new bonded crystals, and the fabrication method of saturable absorbers. Finally, the future prospects of 2 μm solid-state lasers for lidar are presented. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

33 pages, 26020 KiB  
Review
Development of Laser Processing Carbon-Fiber-Reinforced Plastic
by Zhonghe Wang, Yao Ma, Boshi Yuan, Chunting Wu, Changqing Li and Shuwei Sun
Sensors 2023, 23(7), 3659; https://doi.org/10.3390/s23073659 - 31 Mar 2023
Cited by 2 | Viewed by 3565
Abstract
Due to its exceptional advantages, such as high specific strength, high specific modulus, and good fatigue resistance, carbon-fiber-reinforced plastic (CFRP) is frequently utilized in aerospace, aviation, automotive, rail transportation, and other areas. Composite components typically need to be joined and integrated. In the [...] Read more.
Due to its exceptional advantages, such as high specific strength, high specific modulus, and good fatigue resistance, carbon-fiber-reinforced plastic (CFRP) is frequently utilized in aerospace, aviation, automotive, rail transportation, and other areas. Composite components typically need to be joined and integrated. In the equipment manufacturing industry, the most used methods for processing composite components are cutting, drilling, and surface treatment. The quality of CFRP is significantly impacted by traditional mechanical processing, causing flaws like delamination, burrs, and tears. Laser processing technology has emerged as a crucial method for processing CFRP for its high quality, non-contact, simple control, and automation features. The most recent research on the laser processing of CFRP is presented in this paper, supporting scientists and engineers who work in the field in using this unconventional manufacturing technique. This paper gives a general overview of the key features of laser processing technology and the numerous machining techniques available. The concepts and benefits of laser processing technology are discussed in terms of the material properties, mode of operation, and laser characteristics, as well as the methods to achieve high efficiency, low damage, and high precision. This paper reviews the research development of laser processing of carbon-fiber-reinforced plastics, and a summary of the factors affecting the quality of CFRP laser processing. Therefore, the research content of this article can be used as a theoretical basis for reducing thermal damage and improving the processing quality of laser-processed composite materials, while, on this basis, we analyze the development trend of CFRP laser processing technology. Full article
(This article belongs to the Special Issue Important Achievements in Optical Measurements in China 2022–2023)
Show Figures

Figure 1

Back to TopTop