Journals >Laser & Optoelectronics Progress
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2010
Volume: 47 Issue 12
23 Article(s)
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Atmospheric Optics and Oceanic Optics
Ocean Red Tide Monitoring Method Based on Blue-Green Lidar
Lin Hong, Wang Xinmin, Lu Jinjun, and Li Weizhong
A method for red tide detecting and monitoring by the airborne blue-green lidar is proposed based on analyzing the blue-green optical properties of the seawater. The blue-green laser can enter the seawater deeply, and the information of red tide in the deep seawater can be detected by using the blue-green lidar. By detA method for red tide detecting and monitoring by the airborne blue-green lidar is proposed based on analyzing the blue-green optical properties of the seawater. The blue-green laser can enter the seawater deeply, and the information of red tide in the deep seawater can be detected by using the blue-green lidar. By detecting the blue-green light scattering signal under the seawater, the information of red tide density can be gained. A red tide density detecting model based on airborne blue-green lidar is established through analyzing the absorbing and scattering characteristics of the red tide. By emulating and computing, it is proved that the method can detect and monitor the density of the ocean red tide effectively, and therefore it can also predict the occurrence of red tide..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 120101 (2010)
Diffraction and Gratings
Technology of Making Chromium Mask Using Digital Photolithography System
Yan Lihua, Xu Ranran, and Gong Yongqing
A way to make mask patterns by using digital photolithography system based on digital micro-mirror device(DMD) is proposed. Firstly, a cartographic software is applied to make the mask patterns of diffractive optical elements, which include binary grating, Fresnel zone plate and so on. Then, by importing these patternsA way to make mask patterns by using digital photolithography system based on digital micro-mirror device(DMD) is proposed. Firstly, a cartographic software is applied to make the mask patterns of diffractive optical elements, which include binary grating, Fresnel zone plate and so on. Then, by importing these patterns to DMD and taking advantage of the spatial light modulation characteristics of DMD, the corresponding patterns on chromium plates are sculptured after the process of highly minified projection exposure. Finally, the required mask patterns are produced after the etching and photo resist stripping of the patterns mentioned above. Applying these prepared mask patterns to reduced optical system, patterns with submicron structure will be produced on silicon wafers, which can fully meet the requirement of high resolution. The method unifies the characteristics of the traditional photoetching craft and the DMD digitization hypothesized mask. Compared with the way of laser beam vertical writing and the particle beam etching, the method is convenient, highly effective, and low cost to obtain mask patterns..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 120501 (2010)
Fiber Optics and Optical Communications
Influence of Lateral Deformation on Polarization Beat-Length Dispersion of Holey Birefringence Fiber
Shi Zhidong, He Wei, Lin Jianqiang, Li Mingjia, and Ji Minning
In order to produce fiber-optic polarization components and devices, a simple scheme is proposed for a birefringence holey fiber to improve dispersion characteristics of its polarization beat-length. The cross-section of the birefringence holey fiber with circular micro-holes cladding array and a pair of large holes neIn order to produce fiber-optic polarization components and devices, a simple scheme is proposed for a birefringence holey fiber to improve dispersion characteristics of its polarization beat-length. The cross-section of the birefringence holey fiber with circular micro-holes cladding array and a pair of large holes near the cores is squeezed or expanded in orthogonal directions. To deduce the wavelength sensitivity of polarization beat-length, compensation and equilibrium are made among the birefringence dispersion curves with opposite signs induced by multiple asymmetric structures. The influence of different structural parameters on the modal birefringence is calculated and analyzed through full wave beam propagation method. By optimization to the structural parameters, a flatten dispersion curve of polarization beat length is obtained in 1550 nm wavelength windows with the central beat-length value around 39.5 mm. The relative variation of beat-length is 1.27% in wavelength range 1380~1750 nm. If this fiber is made into zero-order quarter wave plate in 1550 nm wavelength window, the operation wavelength band is about 1400~1710 nm under the retardation tolerance of 2π/300 and the relative bandwidth is up to 20%..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 120601 (2010)
Analysis of Mode Scalability in Large Mode Area Fibers
Liao Suying
In order to obtain a large-mode-area fiber structure to improve fiber lasers′ output power, several technical measures have been adopted to scale the fiber mode field size. However, with the mode field size increasing, the fiber waveguide′s ability to confine the mode field declines, which limits the growth of the modeIn order to obtain a large-mode-area fiber structure to improve fiber lasers′ output power, several technical measures have been adopted to scale the fiber mode field size. However, with the mode field size increasing, the fiber waveguide′s ability to confine the mode field declines, which limits the growth of the mode field size. Based on the fiber eigen-mode field theory, the mode field distributions of the large-mode-area fibers are discussed, and the limitation effects of the mode field size growth imposed by mode coupling and mode distortion are analyzed. Considering the impact of the limitations, the mode field distributions of several refractive index fibers are calculated by using the finite element method. The mumerical results show that the product of the equivalent mode area and the square difference of the effective refractive index between two adjacent modes tends to a constant, which constrains, the scalability of the fiber mode field..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 120602 (2010)
Performance Studies on Er3+-Doped Amplifier Based on Bragg Fiber with High Index Core
Sun Tingting, Wang Zhi, and Zhao Lilong
Characteristics of Er3+-doped amplifier based on Bragg fiber with high index core are investigated. Small signal gain and noise figure are measured for forward pump configuration and backward pump configuration. The results show that, compared with conventional Er3+-doped fiber amplifier, Bragg fiber amplifier has simiCharacteristics of Er3+-doped amplifier based on Bragg fiber with high index core are investigated. Small signal gain and noise figure are measured for forward pump configuration and backward pump configuration. The results show that, compared with conventional Er3+-doped fiber amplifier, Bragg fiber amplifier has similar amplified spontaneous emission but lower gain. With the simulation on mode field of doped Bragg fiber, the result is discussed and improving method is proposed. Moreover, characteristics of saturated gain are also studied. It is shown that Bragg fiber amplifier has larger input-dynamic-range and has potential application in automatic gain control..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 120603 (2010)
High-Frequency and High-Power Laser Modulator in Space Optical Communications
Zhan Weida, Li Hongzuo, Wang Zhijian, and Jiang Huilin
The modulator frequency and output power directly affect the communication rate and link distance in the space optical communications. Considering two specifications of high modulation frequency and high output optical power, a method of adopting transverse modulation and combined modulation is proposed, and LiNbO3(LN)The modulator frequency and output power directly affect the communication rate and link distance in the space optical communications. Considering two specifications of high modulation frequency and high output optical power, a method of adopting transverse modulation and combined modulation is proposed, and LiNbO3(LN) crystal structure and parameter optimization, optical coupling design and power calculation, RF-driven source design, technical analysis of automatic bias are carried out. A laser modulator is designed whose maximum modulation frequency is up to 1238 MHz, output optical power is greater than 1 W, half-wave voltage is about 266 V, maximum phase delay is about 1.39 rad, reduction factor is about 0.99, and extinction ratio is about 20 dB. Experiments show that the theoretical design is consistent with experimental results, and the laser modulator can be applied to the space optical communication demonstration experiments on the ground whose bit error rate is better than 10-9 and the link distance is more than 7 km. It can also be applied in the near space or deep space optical communications..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 120604 (2010)
Preparation and Optical Performance of Large Numerical Aperture Image Transfer Fiber
Zhou Dechun, Yu Fengxia, Tan Fang, Liu jinghe, and Cui Yuan
High quality core and clad glass with good physicochemical matching properties is prepared, La2O3 as core glass for its large cationic diameter and low refractive index material as clad glass. Rod-tube draw technique is adopted to prepare image transfer single fiber which, a kind of double clad fiber, is tested afterwaHigh quality core and clad glass with good physicochemical matching properties is prepared, La2O3 as core glass for its large cationic diameter and low refractive index material as clad glass. Rod-tube draw technique is adopted to prepare image transfer single fiber which, a kind of double clad fiber, is tested afterwards. This experiment gains image transfer fiber material, whose single fiber diameter is 30 μm, transmittance is 48%/m, core-clad concentricity error is 0.01%, and numerical aperture is 0.82. These results indicate optical acceptance angle of this fiber material reaching 110°. Optical collection ability is greatly improved..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 120605 (2010)
Geometric Optics
Design of Light Guide Plate for Large-Size LED Silm Light Box
Yin Jie, Qiu Yunfeng, Liu Qiao, and Wang Yi
The working principle of light guide and the light guide network design theory have been discussed. The formula for the distribution of non-uniform network is derived by using reflection, refraction, scattering theory of geometrical optics, and a large-size bilateral-edge LED backing guide plate is designed. The light The working principle of light guide and the light guide network design theory have been discussed. The formula for the distribution of non-uniform network is derived by using reflection, refraction, scattering theory of geometrical optics, and a large-size bilateral-edge LED backing guide plate is designed. The light guide plate model is debuged and simulated by using optical simulation software. And taking full account of the cost and feasibility, the result of uniformity is very close to 80%, which fully meets the need of advertising light boxes..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 120801 (2010)
Holography
Nonuniform Quantization Digital Holography and Its Application in Information Hiding
Chen Jiazhen, Zheng Zihua, Lian Guiren, and Ye Feng
A nonuniform quantization encoding method for Fourier transform digital holography is proposed. The generated digital holography in quantization noise power aspect has been analyzed and compared with the uniform quantization holography. The simulation results show that the nonuniform quantization method can bring lowerA nonuniform quantization encoding method for Fourier transform digital holography is proposed. The generated digital holography in quantization noise power aspect has been analyzed and compared with the uniform quantization holography. The simulation results show that the nonuniform quantization method can bring lower quantization noise power and better quality of the reconstructed image under the condition of the same encoding bits. A clearer digital reconstructed image can be retrieved from the carrier image embedded with nonumiform quantization digital holographic watermark when suffered from the same intensity of the Gaussian noise or salt and pepper noise. The similar robustness is also shown in anti-cropping and anti-JPEG compression performance. The proposed method can be used in the pre-processing stage of the holographic watermark in information hiding application or digital storage, transform and processing of the hologram, etc..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 120901 (2010)
Image Processing
Introduction and Comparison of Range Image Registration Methods
Liu Xiaoli, Peng Xiang, Yin Yongkai, and Li Ameng
Registration of range images plays a key role in 3D digital imaging and modeling and 3D optical inspection. Its precision and velocity directly determine the quality of 3D model construction. At present, two registration methods, iterative closest points and markers, are in wide application. All kinds of methods for raRegistration of range images plays a key role in 3D digital imaging and modeling and 3D optical inspection. Its precision and velocity directly determine the quality of 3D model construction. At present, two registration methods, iterative closest points and markers, are in wide application. All kinds of methods for range images registration are summarized, where iterative closest points method and markers method are introduced mainly. According to experimental results, these two methods are compared in various regions, including registration-error, registration-time, error-source, application-areas and so on..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 121001 (2010)
Instrumentation, Measurement and Metrology
Design of 90° Tiling off-Axis Parabolic Mirror Based on Focusing Terminal of High-Power Solid-State Laser
Yang Yuchuan, Jing Feng, Li Fuquan, Wang Xiao, Huang Xiaojun, Feng Bing, and Luo Hui
Off-axis parabolic mirror is extensive used in non-aberrant targeting by high energy short-pulse solid-state laser. With the incremental requirement for focal energy, the multi-laser focal target is often applied, which puts forward a new request for focusing element. The large-bore tiling parabolic mirror can ensure mOff-axis parabolic mirror is extensive used in non-aberrant targeting by high energy short-pulse solid-state laser. With the incremental requirement for focal energy, the multi-laser focal target is often applied, which puts forward a new request for focusing element. The large-bore tiling parabolic mirror can ensure more that the profile accuracy is over λ/4 and has good augmentability. 90° off-axis design can effectively increase focal efficiency. Based on geometrical optics and diffraction optics, the focal character of 90° off-axis segmented parabolic mirrors has been studied and the misalignment of angle and position are concerned. The results show that the out-of-plane tilt/tip and piston are the main factor affecting strehl ratio and power ratio in a 20 μm-dia meter barrel, discarding the in-plane rotary and decent in active control. The accuracy of tilt/tip and pistion are respective ±0.5 μrad, ±105.3 nm, and the focal performance is predicted by Monte-Carlo tolerance analysis. Under the situation, the ideal focal spot can be afforded for application..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 121201 (2010)
Portable Larvae Image Analyzer for Plant Quarantine
Yu Guiying, Jiang Xianman, Fan Weijun, and Sang Ru
With the invasion of alien organisms becoming a global environmental problem, it needs a instrument for the on-line detection. A portable image analyzer which can realize on-line larva detection for plant quarantine is demostrated. The instrument adopts zooming optical system with a 0.7～9 zoom by rotating zoom ring. ThWith the invasion of alien organisms becoming a global environmental problem, it needs a instrument for the on-line detection. A portable image analyzer which can realize on-line larva detection for plant quarantine is demostrated. The instrument adopts zooming optical system with a 0.7～9 zoom by rotating zoom ring. The apparatus has a light emitting diode(LED) reflective uniform illumination system optimized by using orthogonal experiment method. In the scope of Φ50 mm, the uniformity of illumination can reach up to 83.7%. A larva-recognition software is designed to identify and analyze the larvae. The proposed portable larvae image analyzer provides a new on-line detection method..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 121202 (2010)
An Auto-Focus Algorithm Based on Fine and Rough Adjustment for Visual Optical Measurement Imaging System of Shooting Range
Xu Bohong, and Jiang Heping
In order to solve the problem of poor precision in observed target, measured by manual focusing in traditional shooting range optical measurement imaging device with low efficiency and indeterminacy, an algorithm of rapid auto-focusing combining roughly focusing and fine focusing is proposed. This method can automaticaIn order to solve the problem of poor precision in observed target, measured by manual focusing in traditional shooting range optical measurement imaging device with low efficiency and indeterminacy, an algorithm of rapid auto-focusing combining roughly focusing and fine focusing is proposed. This method can automatically search the focal plane by evaluating the image definition. First, the Brenner function with high performance is used to roughly fousing. Tenengrad function with high sensitivity to the change of image definition is used to fine fousing in narrow range later. An algorithm for tracking based on mean shift is applied and hardware platform is set up in experiment. By the focusing experiments repeatedly to the same measuring target in the same place, the results of field test indicate that this method with high stability can satisfy the accuracy and velocity in actual measurement..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 121203 (2010)
Integrated Optics
Temperature Characteristics of Slot-Waveguide Ring Resonators
Song Shijiao, An Junming, Zhao Lei, Wu Yuanda, and Hu Xiongwei
The temperature stability of the slot-waveguide ring resonators which are based on silicon on insulator (SOI) and embedded with SiO2 is simulated and analyzed theoretically. The temperature dependence of the nano-wire ring, slot-waveguide ring, and the slot rings with different structure parameters are compared. In rooThe temperature stability of the slot-waveguide ring resonators which are based on silicon on insulator (SOI) and embedded with SiO2 is simulated and analyzed theoretically. The temperature dependence of the nano-wire ring, slot-waveguide ring, and the slot rings with different structure parameters are compared. In room temperature, near the wavelength of 1.55 μm, the temperature dependence of the 5 μm-radius slot waveguide ring is 0.049 nm/℃, while the temperature dependence of the nano-wire ring is 0.092 nm/℃ at the same case, which is 1.88 times of that of the slot-waveguide ring. The widths of the slot and Si will also affect the temperature characteristic of the slot-waveguide ring resonators, when the slot width increases or the Si width decreases, the slot-waveguide ring resonators′ temperature dependence will decrease further. By using negative temperature coefficient material WIR 30-490 and optimizing the structure parameters of the slop waveguide, the temperature dependence of the resonate wavelength has decreased to 0.0023 nm/℃..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 121301 (2010)
Transmission Properties of TM Modes in Slab Waveguide with Anisotropy and Dispersion Left-Handed Materials
Shen Lufa, and Wang Zihua
A three-layer slab waveguide with left-handed material is investigated. Through Maxwell equations, a dispersion equation for TM oscillating guided modes is obtained and some mode dispersion curves are plotted, respectively. It is found find that they have an abnormal dispersion property and two modes degenerancy near cA three-layer slab waveguide with left-handed material is investigated. Through Maxwell equations, a dispersion equation for TM oscillating guided modes is obtained and some mode dispersion curves are plotted, respectively. It is found find that they have an abnormal dispersion property and two modes degenerancy near cutoff. Besides, the normalized power flux of TM oscillating guided modes in the slab waveguide is studied. The results reveal their power fluxes have positive value, negative value and zero. The positive or negative power flux means energy in waveguide travels forward or backward. But, zero power flux implies all energy is stored in the slab waveguide..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 121302 (2010)
Lasers and Laser Optics
Three-Dimensional Finite Element Simulations of Laser-Generated Lamb Wave on Viscoelastic Thin Plates
Pan Bo, Gao Qian, and Zhang Hua
The propagation characteristics of laser-generated Lamb wave in the three-dimensional thin viscoelastic plate are studied. Based on the theory of the stress-strain relation, the three-dimensional equation of dynamic equilibrium in the frequency domain is derived. Taking account of the viscoelastic property of the materThe propagation characteristics of laser-generated Lamb wave in the three-dimensional thin viscoelastic plate are studied. Based on the theory of the stress-strain relation, the three-dimensional equation of dynamic equilibrium in the frequency domain is derived. Taking account of the viscoelastic property of the material, the three-dimensional model of laser-generated Lamb wave in the frequency domain is established by the finite element method. The process of laser-generated Lamb wave and its propagation are simulated in the three-dimensional thin viscoelastic plate. The numerical results coincide well with the characteristics of the group velocity curve, dispersion curve and attenuation curve which calculated by the analytical method. The results show that the velocities of the s0 and a0 modes increase gradually and the dispersive nature of the a0 mode decreases with the direction normal to the fiber direction gradually turning to the direction along the fiber direction in the unidirectional fiber-reinforced thin viscoelastic plate. In addition, the increase of source-receiver distance along the same direction causes a marked increase in the attenuation of Lamb waves and the attenuation of the higher-frequency signal is stronger than the lower-frequency one..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 121401 (2010)
Simulation and Analysis of Package Parasitic Parameters on Frequency Response Characteristics of Semiconductor Laser
Xiao Yong, and Chen Fushen
Laser diode is one of the core devices in optical communications, and is widely used in communication backbone network between metropolitans. Optoelectronic integrated circuit computer-aided design is an important method for optoelectronic device modeling, and plays an important role in optical communication. The smallLaser diode is one of the core devices in optical communications, and is widely used in communication backbone network between metropolitans. Optoelectronic integrated circuit computer-aided design is an important method for optoelectronic device modeling, and plays an important role in optical communication. The small signal frequency response formula of laser diode is deduced, and the resonance phenomenon of package parasitic parameters is studied, and such a resonance effect is used on the compensation of the chip′s frequency response characteristics. Finally circuit simulation software PSpice is used to analyze the circuit model for small signal frequency response, and the frequency response bandwidth of 3 dB is obtained..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 121402 (2010)
Materials
Synthesis and Up-Conversion Luminescence Properties of BaYF5:Yb3+/Er3+ Nanocrystals
Sun Jiayue, Zhang Weihang, Zhou Wei, and Du Haiyan
Yb3+ and Er3+ co-doped BaYF5: up-conversion nanocrystals are prepared by hydrothermal method. The sample is characterized by scanning electron microscopy and X-ray diffraction. Upon 980 nm laser diode excitation, the effect of hydrothermal synthesis temperatures on up-conversion luminescence properties is discussed. ReYb3+ and Er3+ co-doped BaYF5: up-conversion nanocrystals are prepared by hydrothermal method. The sample is characterized by scanning electron microscopy and X-ray diffraction. Upon 980 nm laser diode excitation, the effect of hydrothermal synthesis temperatures on up-conversion luminescence properties is discussed. Results show that the sample obtained at 200 ℃ has larger green emission intensity than that of other samples, while the sample synthesized by hydrothermal method at 220 ℃ has the average grain size about 100 nm. According to the law of luminescence intensity versus excitation power, the 523 and 546 nm green emission, 649 and 667 nm red emission are all due to the double-photon process. The up-conversion mechanism and processes are also analyzed..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 121601 (2010)
Enhanced Luminescence Properties of Ba2MgSi2O7:Eu2+ Prepared in Air Atmosphere
You Panli, Liu Lijuan, Yao Yadong, Huang Zhongbing, Liao Xiaoming, and Yin Guangfu
A series of Eu-doped Ba2MgSi2O7 phosphors are prepared in air atmosphere by the high temperature solid-state reactions. A reduction of Eu3+ to Eu2+ ion is validated in Ba2MgSi2O7 via emission and excitation spectra measurement. The results show that the photoluminescence (PL) intensity of the Ba2MgSi2O7Eu2+ prepared inA series of Eu-doped Ba2MgSi2O7 phosphors are prepared in air atmosphere by the high temperature solid-state reactions. A reduction of Eu3+ to Eu2+ ion is validated in Ba2MgSi2O7 via emission and excitation spectra measurement. The results show that the photoluminescence (PL) intensity of the Ba2MgSi2O7Eu2+ prepared in air at 1350 ℃ with quench cooling was enhanced about 6 times compared with that of Ba2MgSi2O7Eu2+ prepared in air at 1250 ℃ with furnace cooling. Moreover, the PL intensity of the Ba2MgSi2O7Eu2+ is increased by adding NH4F flux. The PL intensity of Ba2MgSi2O7Eu2+ phosphor containing 4% NH4F (molar fraction) is 5 times as high as that of the Ba2MgSi2O7Eu2+ phosphor without NH4F..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 121602 (2010)
Spectroscopy
Nondestructive Detection of Soluble Solids Content on Navel Orange with Vis/NIR Based on Genetic Algorithm
Xue Long, Li Jing, Liu Muhua, Wang Xiao, and Luo Chunsheng
A rapid quantification technique is developed and validated for nondestructively quantifying the soluble solids content (SSC) of citrus fruits using Vis/NIR spectroscopy in conjunction with partial least squares regression (PLS) using genetic algorithm (GA). The spectral are recorded in the Vis/NIR region from 350 to 1A rapid quantification technique is developed and validated for nondestructively quantifying the soluble solids content (SSC) of citrus fruits using Vis/NIR spectroscopy in conjunction with partial least squares regression (PLS) using genetic algorithm (GA). The spectral are recorded in the Vis/NIR region from 350 to 1800 nm using the fiber optic probe method. The navel orange Vis/NIR spectra data are divided into 15 intervals. Consequently, 5 subsets (wave regions 554~643 nm, 1000~1088 nm, 1089~1177 nm, 1445~1533 nm and 1623~1711 nm respectively) and 446 data points are selected quickly by GA-PLS. The best prediction results for the navel orange in predicted set are 0.9132 and 1.2579 for correlation coefficient and root mean square errors of prediction respectively. With the proposed method, a concise easily computed model can be built to select the characteristic region of Vis/NIR spectroscopy..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 123001 (2010)
Vision, Color, and Visual Optics
Spectral-Based Rendering Method and Its Application in Multispectral Color ReproductionLi Hongning
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Multispectral imaging technology is the key for high-fidelity reproduction of objects in various environments. In computer graphics, the rendering method based on multispectral has obvious advantages compared with those of the traditional three-channel red-green-blue (RGB) color rendering method because of the explicitMultispectral imaging technology is the key for high-fidelity reproduction of objects in various environments. In computer graphics, the rendering method based on multispectral has obvious advantages compared with those of the traditional three-channel red-green-blue (RGB) color rendering method because of the explicit physical meaning of imaging. The basic principle of multispectral imaging is discussed, and the necessary approximation in implementation of multispectral imaging model in computer graphics is analyzed, and a method to synthesize color from spectrum is provided. The multispectral imaging renderer and some problems of realization are simply introduced. Through four cases about color evaluation, object appearance reproduction with different materials, appearance effect of different illuminants and the algorithm of spectral reflectance reconstruction, and the applications of multispectral rendering method are presented..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 123301 (2010)
Study of Objective Refraction Based on Wave-Front Aberrations of Human Eyes
Zhang Zhenhua, Rao Feng, and Wang Zhaoqi
Objective optometry method based on the wave-front aberration data is explored. Wave-front aberrations of human eyes are measured by the wave-front aberrometer, and the wave-front at the plane located at spectacle lens is calculated by use of Fresnel diffraction integral formula. The best spherical power, cylindrical pObjective optometry method based on the wave-front aberration data is explored. Wave-front aberrations of human eyes are measured by the wave-front aberrometer, and the wave-front at the plane located at spectacle lens is calculated by use of Fresnel diffraction integral formula. The best spherical power, cylindrical power and cylindrical axis of the spectacle lens fitting the wave-front are calculated though least-squares method. The results are compared with those computed with the second order coefficients only, and with the Zernike coefficients of the second order as well as the fourth order. It is shown that the mean spherical power difference, the mean cylindrical power difference, and the mean cylindrical axis difference are 1.20 D, 0.13 D and 1.53° respectively from those with the second order Zernike coefficients only, and they are 0.14 D, 0.13 D and 1.37° respectively from those with the second and fourth order Zernike coefficients. Therefore, the method with the second and fourth order Zernike coefficients can reach the accuracy requirement, while the method with the second order Zernike coefficients only has a large discrepacy..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 123302 (2010)
Luminance Effects on Neural Contrast Sensitivity Function at Photopic Level
Ge Jingjing, and Wang Zhaoqi
The influence of the luminance at photopic level on the neural contrast sensitivity function (NCSF) of visual system is studied. The contrast sensitivity function (CSF) of the visual system and the modulation transfer function (MTF) of the eye′s optical system are firstly measured. Then the NCSF is gotten through the cThe influence of the luminance at photopic level on the neural contrast sensitivity function (NCSF) of visual system is studied. The contrast sensitivity function (CSF) of the visual system and the modulation transfer function (MTF) of the eye′s optical system are firstly measured. Then the NCSF is gotten through the calculation method. NCSFs of four individual eyes are respectively determined in the cases of white light (with the luminance of 15, 210 and 310 cd/m2). The results show that, the NCSF of white light mounts up considerably and the curves shift toward higher spatial frequency as the luminance increases. However, the change of NCSF is somehow different from individual to individual. With the increase of luminance, the variation tendency of the CSF is similar to that of the NCSF, while the gain is much larger than that of the NCSF, especially in the region of higher spatial frequency. It is the NCSF, rather than CSF, that reflects the luminance sensitivity in the retina-brain neural system, because the influence of the eye′s optical system is excluded..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2020
- Vol. 47, Issue 12, 123303 (2010)
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