Journals >Opto-Electronic Engineering
Contents
2020
Volume: 47 Issue 6
12 Article(s)
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Research Articles
De-noising algorithm for FOG based on MEEMD and FLP algorithm
Dai Shaowu, Chen Qiangqiang, Liu Zhihao, and Dai Hongde
In order to reduce the influence of noise on the output signal of FOG, a de-noising algorithm of FOG based on modified ensemble empirical mode decomposition (MEEMD) and forward linear prediction (FLP) is proposed. Firstly, the concept of permutation entropy is introduced, and the FOG signal is decomposed and reconstrucIn order to reduce the influence of noise on the output signal of FOG, a de-noising algorithm of FOG based on modified ensemble empirical mode decomposition (MEEMD) and forward linear prediction (FLP) is proposed. Firstly, the concept of permutation entropy is introduced, and the FOG signal is decomposed and reconstructed by using MEEMD. Secondly, the low-order IMF terms of the mixed noise after decomposition is filtered and de-noised by the FLP algorithm. Finally, the signal processed by the MEEMD-FLP is reconstructed to get the result. The static test of a FOG is carried out. The experimental results show that compared with the original FOG signal, the RMSE after de-noising is reduced by 76.77%, and the standard deviation is reduced by 76.76%. It can effectively reduce the influence of noise on the FOG output signal and has higher de-noising accuracy..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 190137 (2020)
A method of designing new Bessel beam generator
Dai Chengwei, Yan Chao, Zeng Qingyu, Li Xiong, Guo Yinghui, Pu Mingbo, WangChangtao, and Luo Xiangang
Catenary nanostructures enable continuous phase control. However, the ordinary catenary nanostructure has narrow width at both ends and is not easy to be fabricated. On the other side, it was difficult to build complex model directly in simulation software CST, and the simulation process was complicated in the past. ThCatenary nanostructures enable continuous phase control. However, the ordinary catenary nanostructure has narrow width at both ends and is not easy to be fabricated. On the other side, it was difficult to build complex model directly in simulation software CST, and the simulation process was complicated in the past. The equal-width catenary slit is proposed to replace the normal catenary slit. And the equal-width catenary-type metasurface has been designed to generate Bessel beam, which provides a new idea for the design of two-dimensional optical de-vices. In the process of modeling and simulation, CST is combined with Matlab for co-simulation, and all operations, such as modeling, simulations, and parameter modification, are completed directly in Matlab. This method can be used to design complex structures, and more ideal simulation results can be obtained combined with the numerical optimization ability of Matlab..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 190190 (2020)
Study on spectral fitting method of quantum dot white LED
Liu Yuanhai, Liu Wen, He Siyu, Jiang Fuchun, Chai Guangyue, and Zhang Wang
Quantum dot materials have the characteristics of narrow luminescence spectrum, adjustable luminescence wavelength and high fluorescence quantum yield. The quantum dot LEDs have more potential in improving color gamut. In this paper, a method of white light generation by blue LED excited CdSe red and green quantum dotsQuantum dot materials have the characteristics of narrow luminescence spectrum, adjustable luminescence wavelength and high fluorescence quantum yield. The quantum dot LEDs have more potential in improving color gamut. In this paper, a method of white light generation by blue LED excited CdSe red and green quantum dots is introduced. The ratio of red and green quantum dots to glue was (1∶60) and (1∶10), and the test range of glue content was 1.4 μL～2.2 μL and 3.0 μL～5.0 μL. The samples were prepared by traditional method and layered structure. The absorption and conversion ratio of blue light in the range of glue amount were tested. The function relationship between glue amount and absorption and conversion was obtained by Matlab fitting. When taking the dots (0.34, 0.3) in white light region formed in the above test glue amount range, the red and green quantum dots were calculated with glue amount of 1.9 μL and 4.55 μL, and the corresponding theoretical spectrum was established according to the spectral calculation formula. According to the above glue amount, the verification samples were made and tested the color coordinates (0.3409, 0.2992) and the homologous spectra were basically coincident with the theoretical spectra..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 190288 (2020)
A highly sensitive cantilever temperature sensor for small-area heat source temperature measurement
Xing Zhiming, Jin Tao, and Zheng Lulu
In this paper, a kind of temperature sensor which can detect a small-area heat source with high sensitivity is designed by using the property of different thermal expansion coefficients of materials. The temperature sensitive element of the sensor is a silicon nitride cantilever beam which is coated with metal on its uIn this paper, a kind of temperature sensor which can detect a small-area heat source with high sensitivity is designed by using the property of different thermal expansion coefficients of materials. The temperature sensitive element of the sensor is a silicon nitride cantilever beam which is coated with metal on its upper surface. Due to the difference of thermal expansion coefficients between the metal and silicon nitride, the cantilever beam will bend in the direction of rapid change of the temperature gradient, and the bending amount will be positively correlated with the temperature when the ambient temperature of the cantilever beam changes. In the experiment, the bending amount of the beam is measured by the optical lever, and the relationship between the temperature and the output voltage of the detector is established by calibration. The results show that the sensitivity of the sensor can reach 4.86 mV/℃ and the temperature resolution can reach 0.04 ℃. In order to verify the applicability of the sensor for measuring the small-area heat source, the heat generated by heat sources of different areas is measured depending on the calorific property of NaYF4 under laser excitation. The results show that it still can be measured even the heatin area is only 0.07 mm2 and the accurate measurement for temperature of the small-area heat source can be realized..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 190296 (2020)
Single-frame far-field wavefront retrieval method based on Walsh function modulation
Kong Qingfeng, Wang Shuai, Yang Ping, Lin Haiqi, Liu Yong, and Xu Bing
The reconstruction of wavefront from single far-field image data has unique advantages in simplicity of structure. However, the traditional wavefront reconstruction algorithm has multiple solutions based on single far-field image, its iterative process easily falls into stagnation. In this paper, based on the analysis The reconstruction of wavefront from single far-field image data has unique advantages in simplicity of structure. However, the traditional wavefront reconstruction algorithm has multiple solutions based on single far-field image, its iterative process easily falls into stagnation. In this paper, based on the analysis of the multi-solution problem of single-frame phase retrieval method, a wavefront reconstruction method based on Walsh function two-dimensional discrete phase modulation is proposed. This method can effectively break the symmetry of near-field wavefront and overcome problem of multiple solutions. The simulation results show that the method can accurately reconstruct wavefront aberration with only one far-field image..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 190323 (2020)
DMD maskless lithography stitching error correction based on motion compensation
Jiang Xu, Yang Xu, Liu Hong, Hu Jun, and Wang Yingzhi
For the digital micromirror device (DMD) lithography equipment, due to the exposed images joint errors which caused by mechanical loading errors, problems such as misalignment and overlap of the exposed images may arise. In order to eliminate the exposure error of DMD during large-area exposure, the error correction meFor the digital micromirror device (DMD) lithography equipment, due to the exposed images joint errors which caused by mechanical loading errors, problems such as misalignment and overlap of the exposed images may arise. In order to eliminate the exposure error of DMD during large-area exposure, the error correction method was studied. Firstly, the exposure error was got by measuring the exposed substrate with a microscope. Then, an error model was established based on the known exposure error. Finally, an error correction based on motion com-pensation for DMD lithography system was proposed based on the error model. This method is different from the existing error correction method. The experimental results show that during the micron image exposure process, the exposure error is reduced by more than 80%, and the DMD exposure center offset distance is reduced from 175 μm to 21 μm. The stitching accuracy of the exposed image is improved effectively, which meets the requirements for high quality and high precision of large-area exposure images..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 190387 (2020)
Electrowetting defect image segmentation based on improved Otsu method
Liao Qinkai, Lin Shanling, Lin Zhixian, Chen Zheliang, Li Tiantian, and Tang Biao
Aiming at the effect of pixel defects on the display of electrowetting electronic paper, an automatic thre-shold detection method based on Otsu is proposed to detect defects. Otsu is a commonly used automatic threshold method that gives satisfactory results when the image histogram is bimodal. However, the electrowettiAiming at the effect of pixel defects on the display of electrowetting electronic paper, an automatic thre-shold detection method based on Otsu is proposed to detect defects. Otsu is a commonly used automatic threshold method that gives satisfactory results when the image histogram is bimodal. However, the electrowetting defect image histogram is usually a single peak, and Otsu method fails. Electrowetting differs from the background contrast due to the filling inks of different colors, making segmentation more difficult. In this paper, the weighting coefficient is introduced before the target variance, and the weight decreases as the cumulative probability of defects increases. The weight keeps a large value before the threshold crosses the peak, and the weight decreases after the peak, ensuring that the threshold is always to the left of the peak in the case of a single peak. The experimental results show that the proposed method can effectively segment the electrowetting defect region, especially in the electro-wetting defect image with lower contrast ratio. The method is closer to 0 compared to the ME value of Otsu, VE, WOV and entropy weighting methods. The proposed method has a better segmentation effect..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 190388 (2020)
Broadband cross-slots fractal nano-antenna and its extraordinary optical transmission characteristics
Liu Juefu, Chen Jiao, Li Kangkang, Liu Yuanyuan, and Zhu Lu
To overcome the disadvantages of narrow frequency band and low transmittance for traditional na-no-antenna, a nano-antenna structure based on cross-slots fractal was designed. The extraordinary optical trans-mission characteristics of the cross-slots fractal nano-antenna and the differences between the cross-slots fracTo overcome the disadvantages of narrow frequency band and low transmittance for traditional na-no-antenna, a nano-antenna structure based on cross-slots fractal was designed. The extraordinary optical trans-mission characteristics of the cross-slots fractal nano-antenna and the differences between the cross-slots fractal nano-antenna and the uniform cross-slots nano-antenna were analyzed by the finite difference time domain method. Meanwhile, the influence of physical parameters on the extraordinary optical transmission characteristics of the cross-slots fractal nano-antenna and the relationship of transmission spectrum of the nano-antenna between the fractal size and the non-fractal size were discussed. The results show that the fractal cross-slots structure is more miniaturized, and realizes extraordinary optical transmission and full 2π phase control of transmission beam, and the transmittance is higher than the uniform cross-slots structure, the full width at half maximum (FWHM) is wider, and the highest transmittance is up to 99.51%. By adjusting the physical parameters, the transmission spectrum exhibits red-shift or blue-shift characteristics, achieving controllability of the transmission spectrum. When h=50 nm, the full width at half maximum is about 356 nm, and the transmittance is still as high as 95.66%, which is generally higher than traditional structures, and the peak transmittance is still greater than 74% at large incident angles (70 degrees). In short, the cross-slots fractal nano-antenna has the characteristics of wide frequency, controllable and adjustable, and more miniaturized structure compared with other nano-antenna structures, and realizes extraordinary optical transmission..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 190422 (2020)
Tunable terahertz structure based on the ferromagnetic film
Zhang Qiang, Zhang Xiaoyu, Xing Yuanyuan, and Zhao Lei
Au film is mainly used to prepare the metal structure of the terahertz (THz) microstructure. When the metal structure is fixed, it is difficult to control the terahertz wave by using the properties of Au film. In this paper, the tera-hertz microstructure based on the soft magnetic FeNHf film with the high permeability Au film is mainly used to prepare the metal structure of the terahertz (THz) microstructure. When the metal structure is fixed, it is difficult to control the terahertz wave by using the properties of Au film. In this paper, the tera-hertz microstructure based on the soft magnetic FeNHf film with the high permeability is designed and fabricated on the high resistivity silicon substrate. The magnetization direction of soft magnetic film is controlled by the external magnetic field H. The THz transmission characteristics and electromagnetic resonance mode of the microstructure under the control of H in split triangular structure are systematically studied. The soft magnetic FeNHf film has the characteristic of magnetic anisotropy. Therefore, the direction of the magnetization M in FeNHf film can be controlled by the external magnetic field H to be perpendicular and parallel to the magnetic field of THz wave, respectively. The THz time domain spectroscopy system is used to test the terahertz transmission characteristic of the microstructure. The finite difference time domain method is used to analyze the THz electromagnetic field distribution and modula-tion mechanism based on the microstructure of the FeNHf film. The experimental results show that the resonance frequency of the split triangular THz microstructure can be modulated under magnetic field. At the frequency of 1.3 THz, the tunability and modulation depth are about 5.7% and 15%, respectively..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 190447 (2020)
Analysis of the transmission characteristics of Hank-Bessel beam in anisotropic ocean turbulence
He Fengtao, Fang Wei, Zhang Jianlei, Yang Yi, Du Ying, and Zhang Bin
Based on the Rytov approximation theory, we analyze the cross-spectral density of Hankel-Bessel (HB) beams in anisotropic ocean turbulence. In this paper, we study the orbital angular momentum (OAM) mode detection probability, the crosstalk probability and the spiral phase spectrum of the HB beam, and establish the OAMBased on the Rytov approximation theory, we analyze the cross-spectral density of Hankel-Bessel (HB) beams in anisotropic ocean turbulence. In this paper, we study the orbital angular momentum (OAM) mode detection probability, the crosstalk probability and the spiral phase spectrum of the HB beam, and establish the OAM mode detection probability model in anisotropic ocean turbulence. The results show that the detection probability of the emission mode is decreased and the spiral phase spectrum is expanded due to the ocean turbulence. Furthermore, with the increase of anisotropy factor, the influence of ocean turbulence on the detection probability of HB beam becomes smaller. Meanwhile, with the increase of the temperature variance dissipation rate and the equilibrium parameter, and the decrease of the dynamic energy dissipation rate, the influence of ocean turbulence on the orbital angular momentum transmission is increased..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 190591 (2020)
Orbital angular momentum Talbot array illuminator based on detour phase encoding
Nie Fangsong, Jiang Meiling, Zhang Mingsi, Cao Yaoyu, and Li Xiangping
Orbital angular momentum (OAM) beam with helical phase distribution has demonstrated important ap-plications in information optics, optical trapping, and optical manipulation. In this paper, we designed a planar optical device which can generate a periodic array of focused orbital angular momentum beams. Based on detouOrbital angular momentum (OAM) beam with helical phase distribution has demonstrated important ap-plications in information optics, optical trapping, and optical manipulation. In this paper, we designed a planar optical device which can generate a periodic array of focused orbital angular momentum beams. Based on detour phase encoding, the phase distribution calculated by fractional Talbot effect is implemented on this planar optical device. The property of this optical device with periodic square and hexagonal structures is simulated by finite difference time domain (FDTD) respectively. The optical device with explicit advantages of being easy to fabricate, splice, dup-licate, and integrate can efficiently prop up the generation of high-quality large-area array-type OAM beams..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 47, Issue 6, 200093 (2020)
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