Journals >Opto-Electronic Engineering
Contents
2020
Volume: 47 Issue 9
11 Article(s)
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Link structure of underwater wireless optical communication and progress on performance optimization
Zhang Yufan, Li Xin, Lv Weichao, Chen Jiawang, Zheng Minhui, and Xu Jing
Underwater wireless optical communication (UWOC) can provide a high-speed and flexible communica-tion link for underwater platforms. This paper introduces the basic structure of a UWOC link and points out the opti-mization schemes for a UWOC system. Absorption, scattering, and turbulence will affect the performance of Underwater wireless optical communication (UWOC) can provide a high-speed and flexible communica-tion link for underwater platforms. This paper introduces the basic structure of a UWOC link and points out the opti-mization schemes for a UWOC system. Absorption, scattering, and turbulence will affect the performance of a UWOC system. A comprehensive study of channel characteristics can guide the design of transmitters, receivers, and related signal processing technologies. The performance of UWOC can also be optimized by multiplexing technologies, single-photon detection technologies, and alignment systems. A comprehensive test platform could provide a necessary test environment for further sea trials and the practical applications of UWOC. The paper is expected to serve as a guideline for researchers related to UWOC..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 9, 190734 (2020)
Research Articles
A calibration method for Lyot filter
WangJia, Liu Yangyi, and Rao Changhui
Lyot filter is widely used in solar observation for spectra-scanning imaging. Calibration experiment at regular intervals is an important work to assure the accuracy and validity of Lyot filter. This paper comes up with a new method to conduct the Lyot filter calibration experiment on-line while traditional method requLyot filter is widely used in solar observation for spectra-scanning imaging. Calibration experiment at regular intervals is an important work to assure the accuracy and validity of Lyot filter. This paper comes up with a new method to conduct the Lyot filter calibration experiment on-line while traditional method requires perfect stability of environment. This method uses monochromatic imaging channel and Lyot filter scanning imaging channel simultaneously, and corrects the scanning data with monochromatic imaging data to correct the impact of environment. The instability of light source caused by disturbance of observation environment is reduced. We apply the calibration method in the high-resolution multi-wavelength solar imaging system to calibrate the Lyot filter in Hɑ (656.28) scanning imaging channel and correct the scanning data with TiO band (705 nm) observation data. The result shows that this method successfully eliminate the impact of the light instability on scanning curve of Lyot filter. The difference between the ideal center and the true center of the filter is more than 0.005 nm. The accuracy of the calibration experiment and the adaptability to environment are promoted..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 9, 190049 (2020)
The consistent of laser pointing and theodolite tracking
Jia Wenwu, Zhang Sanxi, and Lei Tao
The distance between the laser optical axis and the tracking optical axis of the theodolite (axis shift) and the parallelism error of the optical axis cause the tracking position of the theodolite to be inconsistent with the laser pointing position.The analysis of the influence of off-axis and parallelism errors shows The distance between the laser optical axis and the tracking optical axis of the theodolite (axis shift) and the parallelism error of the optical axis cause the tracking position of the theodolite to be inconsistent with the laser pointing position.The analysis of the influence of off-axis and parallelism errors shows that a large amount of shift and parallelism errors will lead to inconsistencies between the laser pointing and the theodolite tracking pointing, which in turn leads to an increase in the blind zone of the laser ranging, a decrease in the operating distance and the accuracy of target positioning. A dynamic correction method for laser pointing based on bias tracking is proposed. By keeping the target always at the center of the laser beam and keeping the laser ranging position consistent with the theodolite tracking and locking position, it effectively solves the effect of laser edge energy drop on the operating distance. For a certain type of theodolite, the blind spot of the target can be reduced from 1 km to 82 m. At the same time, in view of the problem that the bias tracking algorithm needs the initial distance of the target to start the bias tracking, a one-dimensional search method for the target with unknown initial distance is proposed, which greatly improves the search efficiency of the target with unknown initial distance. The method in this paper solves the problem of the consistency between the tracking position of the theodolite and the pointing position of the laser, and greatly reduces the limitation on the shift and parallelism of the laser optical axis and the theodolite tracking optical axis..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 9, 190438 (2020)
Research on field calibration method of straightness in five-degree-of-freedom measurement
Su Yuhao, Duan Fajie, Jiang Jiajia, Fu Xiao, Zhang Cong, and Liu Wenzheng
The field calibration of straightness is an important method to ensure the accuracy of on-line measure-ment. Based on the transceiver integrated laser five-degree-of-freedom measurement structure, the field calibration model was established aiming at the Abbe error, and the imaging error of retroreflector caused by theThe field calibration of straightness is an important method to ensure the accuracy of on-line measure-ment. Based on the transceiver integrated laser five-degree-of-freedom measurement structure, the field calibration model was established aiming at the Abbe error, and the imaging error of retroreflector caused by the calibration platform. According to the calibration model and the angle measurement results of the five-degree-of-freedom measuring device, a compensation method of straightness calibration errors was proposed. Experimental results showed that the calibration coefficient error was within 0.2% when using the calibration method, and the calibration errors of straightness were effectively reduced. The calibration method made the error of calibration coefficient re-duce to less than 0.2%, and effectively improved the accuracy of straightness field calibration..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 9, 190451 (2020)
Lateral support structure for 600 mm primary mirror of laser communication
Li Xiaoming, Zhang Tianshuo, Zhang Jiaqi, Li Xiang, and Zhang Lizhong
The main function of the laser communication large-caliber ground optical transceiver is to establish a communication link with the satellite to realize data transmission between the satellite and the ground station. The 600 mm microcrystalline primary mirror of one laser communication station is heavy, and its workingThe main function of the laser communication large-caliber ground optical transceiver is to establish a communication link with the satellite to realize data transmission between the satellite and the ground station. The 600 mm microcrystalline primary mirror of one laser communication station is heavy, and its working angle changes constantly. In order to decrease the mirror surface error, the support system not only has a 9-pose axial support structure but also simultaneously balances the radial component of gravity of the primary mirror at its working angle by using a radial support structure. Flexible lateral support structures have large size and stress, so it is not suit for the mirror that works in a wide range of rotation. The paper researches the lateral support structure with a mercury band and central shaft, and analyses the impact of mercury band parameters on the surface error. The designed lateral structure has small size and improves the surface quality of the mirror. The measured values of PV and RMS are smaller than λ/5 and λ/37, respectively. These result shows that the designed lateral support structure reaches the design purpose and satisfies the requirements..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 9, 190485 (2020)
Optimizing the location of multiple laser guide stars in ground layer adaptive optical systems
Li Caifeng, Jia Peng, and Cai Dongmei
At present, the ground layer adaptive optical systems are using multiple laser guide stars arranged in regular polygons as reference targets to measure the effects of atmospheric turbulence. Obtaining the optimal posi-tion of laser guide stars becomes an interesting problem to analyze. This paper proposes a method to oAt present, the ground layer adaptive optical systems are using multiple laser guide stars arranged in regular polygons as reference targets to measure the effects of atmospheric turbulence. Obtaining the optimal posi-tion of laser guide stars becomes an interesting problem to analyze. This paper proposes a method to obtain the optimal position of laser guide stars by using a genetic algorithm as the optimization algorithm and a simplified geometry model of the ground layer adaptive optic system as the evaluation function. Furthermore, multi-process, Numba library, and multi-thread techniques methods are used to accelerate calculation speed. Based on these me-thods, real atmospheric turbulence profiles are used to analyze the relationship between the optimal position of laser guide stars with different numbers and the different atmospheric turbulence profiles from the same site, through an example of a ground layer adaptive optics system with 14 arcmin field of view. The results show that the optimal po-sition of laser guide stars in the same site is almost the same and their statistically optimal positions are all regular polygon. Besides, we also find that the spatial resolution of turbulence profiles has strong effects to positions of laser guide stars, showing that the more equivalent layers in the measurement results, the closer the position distribution of laser guide stars is to the regular polygon..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 9, 190515 (2020)
Research on laser frequency locking technology based on temperature and PZT control
Lei Ming*, Yu Huaiyong, Fang Yuan, Xiang Qiang, Yang Yi, and Zhang Lizhe
Aiming at the application requirement of resonator fiber optic gyroscopes, a frequency tracking and lock-ing control scheme based on laser temperature and PZT control is proposed in this paper. By taking advantages ofthe large range of laser temperature tuning as well as the high precision and high dynamicity of PZT tuAiming at the application requirement of resonator fiber optic gyroscopes, a frequency tracking and lock-ing control scheme based on laser temperature and PZT control is proposed in this paper. By taking advantages ofthe large range of laser temperature tuning as well as the high precision and high dynamicity of PZT tuning, trackingof the fiber laser’s central frequency to the fiber ring resonator’s resonance frequency is realized. Typical transmis-sion resonant curve is simulated by mathematical methods. Hardware design, algorithm simulations of temperatureand PZT control scheme are carried out. The influence of control parameters on tracking stability is analyzed. Thedevelopment of laser frequency tracking systems is assembled. The high-precision and long-time tracking of laser’scentral frequency to resonance frequency is realized successfully. The locking precision is low to 4.8×10-9hour under room temperature. The locking precision is low to 9.74×10-8 over 5.5 hours under variable temperature. over oneThis work has laid an important foundation for improving the long-term performance of resonator fiber optic gyros-copes..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 9, 190523 (2020)
Impedance spectroscopy characteristics of nano ZnO doped liquid crystal/polymer film
Zhu Qing, Liu Yourong, Jiang Zhipeng, and Zheng Jihong
In this paper, the electrical impedance spectroscopy characteristics of polymer dispersed liquid crystal (PDLC) doped with nano-zinc oxide rods and its sensing applications are studied. Polymer dispersed liquid crystal films have the characteristics of stable structure, resistance to mechanical impact and easy preparatIn this paper, the electrical impedance spectroscopy characteristics of polymer dispersed liquid crystal (PDLC) doped with nano-zinc oxide rods and its sensing applications are studied. Polymer dispersed liquid crystal films have the characteristics of stable structure, resistance to mechanical impact and easy preparation. By doping nano-zinc oxide rods into the material, the sensing function of polar molecules such as ethanol gas can be realized through the analysis of electrical impedance spectroscopy. In this paper, the complex impedance spectra of thin films encountering ethanol molecules are studied and analyzed through comparative experiments. In addition, the elec-trochemical equivalent circuit was established and analyzed. It was found that the film could sensitively and effec-tively realize the sensing function of the ethanol molecules. The sensitivity and response time of the sensor are fur-ther analyzed and studied. The experimental study and analysis show that nano-zinc oxide rod doped PDLC film is expected to be used as a gas sensor for detecting polarity of ethanol and other materials. It has the advantages of high sensitivity, stable structure, high repeatability, and easy fabrication..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 9, 190540 (2020)
Optimal design of Youla controller for vibration rejection in telescopes
Niu Shuaixu, Jiang Jing, Tang Tao, Yang Tao, and Bao Qiliang
Vibration rejection is a key technology of telescopes with stable accuracy of μrad level. Due to the low-rate sample and large time delay of the image sensor, the conventional control loop cannot well mitigate vibrations, especially the wideband vibrations with wide range and large energy. On the concept of optimal forVibration rejection is a key technology of telescopes with stable accuracy of μrad level. Due to the low-rate sample and large time delay of the image sensor, the conventional control loop cannot well mitigate vibrations, especially the wideband vibrations with wide range and large energy. On the concept of optimal force design, an improved wideband vibration rejection method based on Youla parameterization is proposed to mitigate vibrations for improving the closed-loop performance of telescopes. In the case that the disturbances frequency can be obtained, this method can mitigate wideband vibrations by designing an appropriate Q-filter to accommodate to the wideband vibrations. The simulation and experimental results show that the proposed method greatly improves the wideband vibration rejection ability and closed-loop performance of the system compared with the traditional proportional- integral control method. In addition, this method can be extended to many engineering projects because of its low dependence and easy implementation..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 9, 190547 (2020)
Image dehazing algorithm by combining light field multi-cues and atmospheric scattering model
Wang Xin, Zhang Xudong, Zhang Jun, and Sun Rui
Image captured in foggy weather often exhibits low contrast and poor image quality, which may have a negative impact on computer vision applications. Aiming at these problems, we propose an image dehazing algo-rithm by combining light field technology with atmospheric scattering model. Firstly, taking the advantages ofImage captured in foggy weather often exhibits low contrast and poor image quality, which may have a negative impact on computer vision applications. Aiming at these problems, we propose an image dehazing algo-rithm by combining light field technology with atmospheric scattering model. Firstly, taking the advantages of cap-turing multi-view information from light field camera is used to extracting defocus cues and correspondence cues, which are used to estimating the depth information of hazy images, and use the obtained depth information to cal-culating the scene’s initial transmission. Then use scene depth information to build a new weight function, and com-bined it with 1-norm context regularization to optimizing the initial transmission map iteratively. Finally, the central perspective image of hazy light field images is dehazed using atmospheric scattering model to obtain the final de-hazed images. Experimental results on synthetic hazy images and real hazy images demonstrate that, compared to existing single image dehazing algorithms, the peak signal to noise ratio get 2 dB improvement and the structural similarity raise about 0.04. Moreover, our approach preserves more fine structural information of images and has faithful color fidelity, thus yielding a superior image dehazing result..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 9, 190634 (2020)
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