Contents
2008
Volume: 28 Issue 12
39 Article(s)
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Atmospheric Optics and Oceanic Optics
Laser Speckle Reduction in Retina Imaging Illumination
Li Chao, Jiang Baoguang, Xia Mingliang, Cheng Shaoyuan, and Xuan Li
An adaptive optical system with a liquid crystal spatial modulator device as the wave-front aberration corrector for the human retina imaging was constructed A Shack-Hartmann wave-front sensor was used to test the wave-front aberration of the eye A near-infrared (NIR) laser (808 nm) was used as the beacon light source An adaptive optical system with a liquid crystal spatial modulator device as the wave-front aberration corrector for the human retina imaging was constructed A Shack-Hartmann wave-front sensor was used to test the wave-front aberration of the eye A near-infrared (NIR) laser (808 nm) was used as the beacon light source for measuring the wave-front and the light source for the retina imaging A model eye was constructed to analyse the impact of the laser speckle on retina imaging on camera and wave-front measurement The method of rotating diffuser was confirmed feasible and valid for reducing the speckle And then, the contrast experiment that illuminates the vivo human eye by the laser with the diffuser rotating or not was carried out and the retina images with and without speckle were taken Finally a series of images of the retina cells were obtained after the aberration of the eye was corrected After correction the residual errors of the system aberration were less than 0 1 λ It is testified that the laser speckle can be reduced by rotating diffuser, and the NIR laser after speckle reduction can be used as the beacon light source and the illuminating light for the retina imaging As a result, the human eye aberration can be corrected continuously and a video of the retina can be taken..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2245 (2008)
Diffraction and Gratings
Experiments and Theory of Facular Lattice Generated by Diffractive Axicon
Wu Fengtie, and Jiang Xinguang
A method of producing three-dimensional facular lattice through a diffractive axicon was proposed. Based on the generalized Huygens-Fresnel diffraction integral theory, the characteristics of the facular lattice generated by a collimated monochromatic plane wave obliquely illuminated on a diffractive axicon with a largA method of producing three-dimensional facular lattice through a diffractive axicon was proposed. Based on the generalized Huygens-Fresnel diffraction integral theory, the characteristics of the facular lattice generated by a collimated monochromatic plane wave obliquely illuminated on a diffractive axicon with a large incident angle were analyzed. With different incident angles, the optical intensity distribution along the propagation direction and the diffractive optical intensity in a certain axis distance were numerically simulated. The results indicate that a regular diffractive facular lattice will appear in the maximum diffraction-free distance with the increase of the oblique incident angle. The structures of the facular lattice resemble that of the three-dimensional photonic crystal. The experimental result agrees with the numerical simulation..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2250 (2008)
Dual-Channel Characteristic and Application of the Embedded Grating
Ye Yan, and Chen Linsen
The 0th resonant diffraction characteristic of the embedded grating with incident angle of 45° is analyzed by the rigorous coupled-wave theory. The resonant wavelengths of 0th reflection light are 432 nm and 420 nm for the TE and TM polarization respectively in the plane parallel to the grating vector. The resonanThe 0th resonant diffraction characteristic of the embedded grating with incident angle of 45° is analyzed by the rigorous coupled-wave theory. The resonant wavelengths of 0th reflection light are 432 nm and 420 nm for the TE and TM polarization respectively in the plane parallel to the grating vector. The resonant wavelengths of 0th reflection light are 623 nm and 620 nm for the TE and TM polarization respectively in the plane perpendicular to the grating vector. The resonant wavelength of 0th reflection light is far different between these two planes and shows different color. That phenomenon is denoted as dual-channel characteristic and is proved in experiment. The metachromatic device with dual-channel characteristic is made..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2255 (2008)
Fiber Optics and Optical Communications
Amendment of Waveform Distortion of Converted Pulses by Reverse-Direction-Injected Wavelength Conversion
Luo Chuanhong, Zhang Fuju, Guo Jialin, Zhang Jianqiang, and Sun Junqiang
A numerical simulation on wavelength conversion based on a periodically poled lithium niobate waveguide is presented. The evolution of pulses is exhibited and the walk-off between pulses is discussed to explore the influence of two different injecting modes that the pump wave and signal wave are injected from the same A numerical simulation on wavelength conversion based on a periodically poled lithium niobate waveguide is presented. The evolution of pulses is exhibited and the walk-off between pulses is discussed to explore the influence of two different injecting modes that the pump wave and signal wave are injected from the same direction or from the reverse direction. The analysis results demonstrate that the second harmonic generation and the difference frequency generation are simultaneously realized in the same-direction-injected wavelength conversion, which widens the second-harmonic wave continuously because of the walk-off among the reactive pluses due to group-velocity-mismatch, and then the converted pulses produce waveform distortion in the subsequent difference frequency generation. The reverse-direction-injected wavelength conversion is proposed to avoid converted waveform distortion, and it is able to separate two processes of the second order nonlinear effect. It is expected to amend the waveform distortion of converted pulses as well as to improve the conversion efficiency..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2261 (2008)
Variational Effective Index Analysis of Polymer Rib Optical Waveguide
Liao Jinkun, Tang Xionggui, Lu Rongguo, Li Heping, and Liu Yongzhi
Polymer rib optical waveguide is an important component in polymeric integrated optoelectronic devices such as electro-optic modulators. By using effective index method (EIM) to calculate the transverse refractive index distribution and effective index of polymer rib waveguide, the optical field distribution in each rePolymer rib optical waveguide is an important component in polymeric integrated optoelectronic devices such as electro-optic modulators. By using effective index method (EIM) to calculate the transverse refractive index distribution and effective index of polymer rib waveguide, the optical field distribution in each region is expressed as piecewise functions approximately. Based on the scalar wave equation that governs the guided modes,the variational parameter is determined by variational method (VM) for obtaining accurate transverse optical field distribution. The dispersion characteristics and transverse field distribution of the fundamental and higher-order modes are analyzed for polymer rib multimode waveguide. An algorithm is implemented to study the effect of the structural parameters and dimensions on the dispersion characteristics, and the optical field distribution of the fundamental and higher-order modes for TM modes is calculated. The single-mode transmission condition for polymer rib optical waveguide is obtained. The approach has advantages of high precision, small calculation complexity and high efficiency, which will provide theoretical reference and optimization method for the fabrication of polymeric electro-optic devices..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2267 (2008)
Inverse Problem of Pulse Shaping by Pulse Stacking
Zeng Shuguang, and Zhang Bin
For the case of pulse shaping by optical fiber pulse stacker, there exists a problem that how to determine the parameters of optical fiber pulse stacker, such as time delay, attenuation, etc, to generate the temporal pulse shapes required in physical experiments. To solve this problem, the characteristics of incoherentFor the case of pulse shaping by optical fiber pulse stacker, there exists a problem that how to determine the parameters of optical fiber pulse stacker, such as time delay, attenuation, etc, to generate the temporal pulse shapes required in physical experiments. To solve this problem, the characteristics of incoherent and partially coherent pulse stacking have been analyzed quantitatively. Consequently, an inverse calculation method has been proposed, by which the parameters of optical fiber pulse stacker can be calculated simply and exactly for arbitrary temporal pulse shapes. The results show that the pulses stacked by incoherent pulse stacking are quite smooth, whereas the pulses stacked by partially coherent pulse stacking exhibit slight modulation. Furthermore, the stacked pulse shapes using the proposed inverse calculation method fit the given pulse shapes nicely..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2272 (2008)
Image Processing
Detecting Pesticide Residue on Navel Orange Surface by Using Hyperspectral Imaging
Xue Long, Li Jing, and Liu Muhua
The Detection of fruit contaminate with pesticide residue is a public health concern. The pesticide was diluted to 1:20, 1:100 and 1:1000 solution with distilled water. A 3×3 matrix of dilutions was applied to 10 cleaned sample with 120 μL, 200 μL and 400 μL. After 168h, hyperspectral images in the wavelength rangThe Detection of fruit contaminate with pesticide residue is a public health concern. The pesticide was diluted to 1:20, 1:100 and 1:1000 solution with distilled water. A 3×3 matrix of dilutions was applied to 10 cleaned sample with 120 μL, 200 μL and 400 μL. After 168h, hyperspectral images in the wavelength range from 625 nm to 725 nm are taken. The characteristic wavelength images are achieved by principal component analysis (PCA). Combining the 3rd principal component (PC) image with proper image processing methods detects the pesticide residue on navel orange. This research shows that the technology of hyperspectral imaging can be used to effectively detect pesticide residue on fruit surface..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2277 (2008)
Three-Dimensional Orientation Prediction-Based Wavelet Transform for Interference Multi-Spectral Images Compression
Li Yunsong, Ma Jing, and Wu Chengke
According to the characteristics of large aperture static imaging spectrometer (LASIS), a three-dimensional (3D) orientation prediction-based wavelet transform method is proposed. The novelty of this method is that it combines directional prediction into 3D-wavelet. In this way, the prediction selects pixel in the mostAccording to the characteristics of large aperture static imaging spectrometer (LASIS), a three-dimensional (3D) orientation prediction-based wavelet transform method is proposed. The novelty of this method is that it combines directional prediction into 3D-wavelet. In this way, the prediction selects pixel in the most correlative direction and is not limited on the prediction direction. The experimental results show that this 3D orientation prediction wavelet improves the performance of wavelet obviously particularly on LASIS image with quite severe direction. Followed with the same quantization and coding methods, the proposed method outperforms the original 3D lifting wavelet by 1 dB. Meanwhile, the spectrums recovered by the proposed method also possesses better performance..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2281 (2008)
Imaging Systems
Main Active Constituent Detection of Cortex Phellodendri Chinensis by Spectral Imaging Technology
Zhao Jing, Pang Qichang, Ma Ji, Zheng Xiwen, Meng Qingxia, and Liu Chuanming
The spectral imaging technology is applied to active constituent detection of traditional Chinese medicines (TCMs) in-vivo. The active constituent of cortex phellodendri chinensis-berberine is detected in-vivo by the home-made liquid crystal spectral imaging system. The central wavelength of the light source is 254 nm The spectral imaging technology is applied to active constituent detection of traditional Chinese medicines (TCMs) in-vivo. The active constituent of cortex phellodendri chinensis-berberine is detected in-vivo by the home-made liquid crystal spectral imaging system. The central wavelength of the light source is 254 nm and the selected spectral range is from 480 nm to 700 nm. A series of fluorescent images called spectrum cube are obtained. After analyzing the spectrum section of the spectrum cube of the samples, a high-pass filter is designed based on the spectrum section of berberine, which is the standared sample supplied by national institute for fhe control of pharmaceutical and biological products. The characteristic spectra of the samples are got. The characteristic spectra of cortex phellodendri chinensis from eight sources are compared, as well as that and wampee. The results show that the spectral imaging technology is available to detect TCMs rapidly, accurately, in-vivo, and none-destructively..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2288 (2008)
Two-Step Phase-Shifting Iterative Algorithm of Improving Quality of Reconstructed Image in Digital Holography
Wu Youpeng, Liu Xiangxuan, and Wang Hongxia
In two-step phase-shifting digital holography, the elimination of the zero-order image and conjugate image is directly affected by the phase-shifting error. To eliminate the phase-shifting error and obtain the actual phase-shifting value, the two-step phase-shifting iterative algorithm is presented, based on the statisIn two-step phase-shifting digital holography, the elimination of the zero-order image and conjugate image is directly affected by the phase-shifting error. To eliminate the phase-shifting error and obtain the actual phase-shifting value, the two-step phase-shifting iterative algorithm is presented, based on the statistic property of the phase distribution of the diffraction field in recorded plane. In this method, the initial phase-shifting value is calculated directly from the holograms, and then the sum of the intensity bit errors between the reconstructed image and the holograms is taken as an evaluation function for an iterative algorithm to find the actual phase-shifting value. With this method, any unknown actual phase-shifting value can be found out, so the zero-order image and conjugate image are effectively eliminated, and the quality of the reconstructed image is enhanced. The feasibility and validity of this method are demonstrated by theoretical analysis and optical experimental result..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2292 (2008)
Reconstruction Algorithm of Photoacoustic Tomography with Acoustic Speed Heterogeneity
Zhang Chi, and Wang Yuanyuan
A deconvolution-based reconstruction algorithm is proposed to enhance the precision of the photoacoustic tomography (PAT) with the acoustic heterogeneity. This algorithm does not require the prior knowledge of the acoustic speed distribution. Firstly, a new function was constructed from detected photoacoustic signals, A deconvolution-based reconstruction algorithm is proposed to enhance the precision of the photoacoustic tomography (PAT) with the acoustic heterogeneity. This algorithm does not require the prior knowledge of the acoustic speed distribution. Firstly, a new function was constructed from detected photoacoustic signals, while the correlation between photoacoustic signals was employed to estimate the flight time of acoustic waves between two spatial positions and compensate the acoustic heterogeneity. Then the electromagnetic absorption distribution of the detected tissue can be reconstructed from this new function based on the deconvolution method. It is shown by simulation results that the reconstructed image can correctly indicate the size, location and electromagnetic absorption coefficient of detected objects when the acoustic speed variation is within 10%. This algorithm has a strong robustness to the noise. Since the acoustic speed variation of biological soft tissues is normally lower than 10%, this algorithm is an efficient reconstruction algorithm for the PAT..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2296 (2008)
Instrumentation, Measurement and Metrology
Feasibility Study on Use of Near-Infrared Spectroscopy in Quantitative Analysis of Catechins in Green Tea
Zhao Jiewen, Guo Zhiming, Chen Quansheng, and Lü Qiang
Near-infrared spectroscopy (NIR) combined with partial least squares (PLS) for the prediction of catechins compounds in the green tea was developed. The original spectra of tea in wavelength range of 10000～4000 cm-1 was acquired. Reference measurement of epigallocatechin gallate (EGCG), epicatechin gallate (ECG) and epNear-infrared spectroscopy (NIR) combined with partial least squares (PLS) for the prediction of catechins compounds in the green tea was developed. The original spectra of tea in wavelength range of 10000～4000 cm-1 was acquired. Reference measurement of epigallocatechin gallate (EGCG), epicatechin gallate (ECG) and epigallocatechin (EGC) were performed by reversed-phase high-performance liquid chromatography (HPLC). PLS is used to perform the calibration models to predict the contents of EGCG, ECG and EGC. To decide upon the number of PLS factors included in the PLS model and the method of spectra preprocessing, the model with the lowest root mean square error of cross-validation (RMSECV) for the training set is chosen. The correlation coefficient between the predicted and the reference results for the test set is used as an evaluation parameter for the models. The results show that the correlation coefficients of the prediction models are 0.9800 for the EGCG, 0.9763 for the ECG and 0.9853 for the EGC, with root mean squared error of prediction (RMSEP) 0.3509, 0.1147 and 0.1365 respectively. The study demonstrates that NIR spectroscopy with PLS can be used sucessfully to determine the content of RGCG, RCG and EGC in green tea..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2302 (2008)
Theoretical Study of Arbitrary Step-Height Measurement Based on Wavelength-Scanning Talbot Effect
Zhang Chengyi, Li Chuanqi, and Pei Shixin
Recently, arbitrary multi-dimensional step-height measurement has attracted much attention. Two wavelength Talbot effect or wavelength-scanning Talbot effect is implemented for the arbitrary step-height measurement. The main advantages of the method are non-mechanical scanning, high stability because of its common-pathRecently, arbitrary multi-dimensional step-height measurement has attracted much attention. Two wavelength Talbot effect or wavelength-scanning Talbot effect is implemented for the arbitrary step-height measurement. The main advantages of the method are non-mechanical scanning, high stability because of its common-path geometry and compactness. Without any mechanical movement of the grating or the detector in the longitudinal direction, the system is free from phase ambiguity problem and measurement errors caused by it. Instead of phase information, the maximum contrast of the high visibility bands is used to judge the occurrence of Talbot image, Ronchi grating with an open ratio of 0.5 is used for the periodic structure diffraction object, step-height measurement is given by the distance of self-image planes. Since the technique measures the fringe contrast rather than absolute intensity, accuracy of the step-height measurement depends on the fringe contrast. It is important that acquirement and judgement of the maximum contrast of the high visibility bands. It is pointed out that the smaller the pitch of the grating is, the better the lateral spatial resolution of the system will be. Further, non-Ronchi grating such as sinusoidal grating or phase grating can be used to improve the maximum contrast of the high visibility bands..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2307 (2008)
Precise Location of Laser Spot Center Based on Residual Pruning
Lu Quan, Liu Shangqian, and Wang Huifeng
For the precise location of laser spot center on the complex target, a method based on residual pruning with geometric feature constraints is proposed. Firstly, the laser spot is extracted by analyzing the character of imaging. Then, the edge of laser spot is pruned twice with the geometric feature constraints to optimFor the precise location of laser spot center on the complex target, a method based on residual pruning with geometric feature constraints is proposed. Firstly, the laser spot is extracted by analyzing the character of imaging. Then, the edge of laser spot is pruned twice with the geometric feature constraints to optimize the edge. Finally, the location of laser spot center is acquired accurately by using the least square fitting method. And it’s applied to the curvature measurement, an important status parameter of cannon. Experimental results show that the method proposed is quite stable, fast and accurate. Compared with the traditional location methods, the horizontal and vertical location errors of laser spot on the complex target are both improved from±1.2 pixel to±0.2 pixel. And the time of a signal location is less than 0.31s. It can accomplish the location of laser spot center on the complex target with high speed and accuracy..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2311 (2008)
Theoretical and Experimental Analysis of an Active Optic Fiber Hydrophone
Gu Hongcan, Yuan Bingcheng, Huang Junbin, Tan Bo, Li Rizhong, and Li Yu
The acoustic sensing characteristics of an active optic fiber hydrophone was analyzed. The fiber laser sensor is made by writing Bragg grating with πphase-shift into a section of Er-doped fiber. Acoustic pressure applied to the fiber laser induces laser wavelength shift. The wavelength shift is demodulated through inteThe acoustic sensing characteristics of an active optic fiber hydrophone was analyzed. The fiber laser sensor is made by writing Bragg grating with πphase-shift into a section of Er-doped fiber. Acoustic pressure applied to the fiber laser induces laser wavelength shift. The wavelength shift is demodulated through interferometric interrogation scheme, and the acoustic pressure information is obtained. The sensitivity experiment shows that the sensitivity is -1665 dB(reference value, 1 rad/μPa). Four optic fiber hydrophones were spliced along a single fiber to form an array. A band-pass wavelength division multiplexer was used to separate the composite interferometer signal into discrete channels and demodulate the acoustic pressure information. The experiment shows that the crosstalk of the array is less than -60 dB, and it will not affectthe dynamic response range of a single hydrophone..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2316 (2008)
Analysis of Diffraction Wavefront Error in Point Diffraction Interferometer
Ma Qiang, Liu Weiqi, Li Xiangbo, Kang Yusi, Wei Zhonglun, Feng Rui, and Liu Hua
The diameter of pinhole or fiber is a critical element that affects the precision of point diffraction interferometer (PDI). The dimension of the aperture is determined by variational accuracy of practical measurement. Based on the scalar diffraction theory, the deviation between diffraction wavefront and sphericity arThe diameter of pinhole or fiber is a critical element that affects the precision of point diffraction interferometer (PDI). The dimension of the aperture is determined by variational accuracy of practical measurement. Based on the scalar diffraction theory, the deviation between diffraction wavefront and sphericity aroused by the dimensions of the aperture is simulated and analyzed. The results show the wavefront error of the optical system is about 0.07 nm peak-vally value (PV) when the numerical aperture (NA) is 0.3 and the aperture diameter is 2.5 μm. The method and results of simulation analysis provide theory and data reference for choosing the dimension of aperture along with the analysis or design of PDI for various testing tasks of accuracy requirement..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2321 (2008)
Optical Radiometric Calibration Based on Parametric Down-Conversion Effect
Li Jianjun, Zheng Xiaobing, Lu Yunjun, Zhang Wei, and Zou Peng
A new calibration method of detectors by using correlated photons generated in spontaneous parametric down-conversion effect of nonlinear crystal is proposed. A CW ultraviolet (351 nm), diode-pumped, frequency-doubled, solid-state laser is used to pump BBO crystal. The degenerate parametric down-conversion (PDC) photonA new calibration method of detectors by using correlated photons generated in spontaneous parametric down-conversion effect of nonlinear crystal is proposed. A CW ultraviolet (351 nm), diode-pumped, frequency-doubled, solid-state laser is used to pump BBO crystal. The degenerate parametric down-conversion (PDC) photons with wavelengths of 702 nm were produced and by tuning crystal angle, nondegenerate PDC photons with wavelengths of 633nm and 789nm were also produced. The quantum efficiencies of the photomultiplier at the above wavelengths were measured respectively. An absolute calibration system of detector quantum efficiency was performed. And its principle and experimental setup were introduced. The calibration uncertainties of PDC method were analyzed systematically. The results show the total calibration relative uncertainties are less than 5.5%. In the end, a comparison between PDC effect method and conventional method based on standard detectors was performed. The results show that the relative difference of the two methods is less than 10%..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2325 (2008)
Temperature and Density Distribution Measurement of Flame by Using Moiré Deflection Tomography
Chen Yunyun, Song Yang, He Anzhi, and Li Zhenhua
The filtered moiré deflection tomography is proposed to diagnose multi-component complex flow fields which contain chemical reactions. As an example, the combustion of propane is chosen as the measured field. The offset of moiré fringe is refined and transformed to deflection angle. The refractive-index distrThe filtered moiré deflection tomography is proposed to diagnose multi-component complex flow fields which contain chemical reactions. As an example, the combustion of propane is chosen as the measured field. The offset of moiré fringe is refined and transformed to deflection angle. The refractive-index distribution of field is reconstructed by deflection filtered back projection (DFBP), and the three-dimensional temperature and density distributions of a certain cross section at two different situations are given. By contrast, multi-component complex flow fields should not regard air as the studied object, chemical reaction and resultant of flow field must be considered , and the equivalent G-D constant and molecular weight of mixed flow field must be amended, according to specific conditions of the measured objects..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2330 (2008)
A Method for Roll-Angle Measurement in Multi-Degree-of-Freedom Measuring System
Cao Rui, Zhang Bin, Feng Qibo, Fang Hengchu, and You Fengling
A roll-angle error measurement method which can be integrated with other parameters measurement system is proposed. The light source, single-mode fiber-coupled laser module with thermo-electric cooler (TEC) is used to decrease the laser beam drift, and provide reference beam for accurate and stable measurement. A speciA roll-angle error measurement method which can be integrated with other parameters measurement system is proposed. The light source, single-mode fiber-coupled laser module with thermo-electric cooler (TEC) is used to decrease the laser beam drift, and provide reference beam for accurate and stable measurement. A special prism is used as a sensitive part, and the roll-angle error is obtained through straightness error of the two beams from the special prism. The experimental procedures and results are presented. The results indicate that the system has good repetition and stability. Compared with electronic gradienter, the method for roll-angle error measurement is available, and the accuracy is about 2″..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2344 (2008)
Lasers and Laser Optics
Research of Multi-Segments Liquid Laser System Connected in Series
Li Mi, Su Yi, Song Yingsong, and Xu Zheng
Liquid laser system has prominent predominance in restraining heat distortion and can achieve stable high-power laser output in long time. In liquid laser system, the gain distribution by ordinary two-sides-pumping has the characteristic of strong gain at the edge but weak at the center and it is very difficult to achiLiquid laser system has prominent predominance in restraining heat distortion and can achieve stable high-power laser output in long time. In liquid laser system, the gain distribution by ordinary two-sides-pumping has the characteristic of strong gain at the edge but weak at the center and it is very difficult to achieve single transverse mode output. A kind of multi-segments liquid laser system connected in series, with pumping mode between side-pumping and end-pumping is introduced, and the gain distribution and the transmission loss in the resonator are simulated. The simulated results show that the multi-segments liquid laser system connected in series can achieve approximate Gaussian gain distribution, the laser beam quality is very excellent, the transmission loss is little and the laser energy transmission efficiency is higher than 30%..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2349 (2008)
Study on the Properties of SL7510 Type Photosensitive Resin for Laser Curing Rapid Prototyping
Huang Biwu, Chen Weifan, and Chen Weiqing
The properties of Huntsman SL7510 type photosensitive resin were investigated by using a FT-IR spectrometer, a stereolithography apparatus, a spinning viscometer, a universal testing machine and a thermomechanical analysis meter. The experimental results showed that the photosensitive resin belongs to an epoxy-acrylic The properties of Huntsman SL7510 type photosensitive resin were investigated by using a FT-IR spectrometer, a stereolithography apparatus, a spinning viscometer, a universal testing machine and a thermomechanical analysis meter. The experimental results showed that the photosensitive resin belongs to an epoxy-acrylic hybrid photosensitive resin, its viscosity at 30 ℃ is 335 mPa·s, its critical exposure (Ec) is 10.9 mJ/cm2, its penetration depth (Dp) is 0.14 mm, its cured volumetric shrinkage is 4.03%, the tensile strength of its cured product is 40.8 MPa, the tensile modulus of its cured product is 2009.2 MPa, the elongation at break of its cured product is 13.6%, and the glass transition temperature of its cured product is 62 ℃. According to the determined Ec and Dp values of the photosensitive resin, the processing parameters of the stereolithography apparatus were chosen to fabricate the part of a telephone shell, and the quality of the fabricated part was good..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2354 (2008)
Longitudinal Evanescent-Wave Pumped Whispering-Gallery-Mode Fibre Laser
Xiang Wenli, Pu Xiaoyun, Bai Ran, Zhang Yuanxian, and Jiang Nan
A new kind of low threshold optical fiber laser has been fabricated by immersing a fused silica optical fiber into a low refractive index dye solution. Pumped by evanescent wave along the fiber axis, dye gain is confined in the evanescent field of whispering gallery mode (WGM) of the fiber, which leads to a low pumpingA new kind of low threshold optical fiber laser has been fabricated by immersing a fused silica optical fiber into a low refractive index dye solution. Pumped by evanescent wave along the fiber axis, dye gain is confined in the evanescent field of whispering gallery mode (WGM) of the fiber, which leads to a low pumping threshold for lasing emission. The concentration effects in liquid dye lasing emission have been studied via a WGM fibre laser under the pumping energy of 50 μJ. The results show that with the increase of rhodamine 6G dye concentration in ethanol alcohol, lasing wavelength is red shifted and lasing wavelength range is widened. The experimental observations are well explained by the γ(λ) curve, a ratio of molecular density for the upper and total lasing energy levels, which is deduced from the four-energy level model of dye lasing from a WGM fibre laser. The low threshold optical fiber laser provides a convenient way to study liquid dye lasing phenomenon..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2359 (2008)
Theoretical and Experimental Study of LD Pumped Nd:YVO4 Yellow Laser with Sum-Frequency Generation
Zhang Juncheng, Wang Jiaxian, Su Peilin, Han Lei, and Xiong Gangqiang
In order to attain optimal sum-frequency 593 nm yellow laser, using LD end-pumped Nd:YVO4, starting from the four-level system rate equations, a theoretical model of the spatial related dual-wavelength rate-equation was established and dual-wavelength photon number expression was conducted. The parameters of the three-In order to attain optimal sum-frequency 593 nm yellow laser, using LD end-pumped Nd:YVO4, starting from the four-level system rate equations, a theoretical model of the spatial related dual-wavelength rate-equation was established and dual-wavelength photon number expression was conducted. The parameters of the three-mirror compound resonator were theoretically obtained for the LD end-pumped Nd:YVO4／KTP yellow laser with sum-frequency in the case of equal dual-wavelength photon number density. The output power of 593 nm yellow laser was experimentally compared under the conditions that dual-wavelength laser photon number density was equal and the dual-wavelength laser oscillation threshold was equal. Output power of 593 nm yellow laser was respectively 410 mW and 340 mW, and the conversion efficiency was 3.4% and 2.8% in the two cases with 12 W pump power. The experimental results show that more efficiency yellow laser can be obtained in the case of equal dual-wavelength photon number density..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2365 (2008)
Materials
Study on Display Character of Electrophoretic Liquid Used in Electronic Paper
Duan Xiaoxia, Huang Shihua, Teng Feng, Xu Zheng, and Liang Chunjun
Organic pigments Hansa Yellow (P.Y.3), Sudan Black and right stabilizer were selected to prepare a new kind of electrophoresis. The stability was improved by adjusting the quantity of every component in the electrophoretic suspensions. The charging mechanism of the pigment and the influencing factors were analyzed. TheOrganic pigments Hansa Yellow (P.Y.3), Sudan Black and right stabilizer were selected to prepare a new kind of electrophoresis. The stability was improved by adjusting the quantity of every component in the electrophoretic suspensions. The charging mechanism of the pigment and the influencing factors were analyzed. The change of the reflectivity and absorption spectrum with voltage direction was studied. Spectral analysis indicates all kinds of absorption confines the display effect. The absorption spectrum shows coherence with reflection spectrum about the display character. The reflection intensity of pigment as well as reflectance, contrast ratio, is different at different wavelength, which determines that a proper light source and radiating wavelength should be selected to monitor the response of display model to the added voltage pulse. In view of both sensitivity and signal intensity, Flurolog-3 fluorescent spectrometer was used to monitor reflection intensity change with pulsed voltage of different period and amplitude at the wavelength of 493 nmwith a 470 nm blue light emission diode as light source and the thickness of the electrophoresis tank as 0.2 mm. An oscillograph was used to to record the change of reflection intensity with driving voltage. At last, the influence of driviing voltage on reflection intensity and response speed is theoretically analyzed..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2370 (2008)
Photophysical Properties of 5,10,15-Tris(Pentafluorophenyl) Corrole and Its Porphyrin Analogue
Zhang Yanwei, Shi Lei, Shen Han, Zhang Guoliang, You Lili, Wen Jinhui, Liu Haiyang, Wang Hui, and Ji Liangnian
The photophysical properties of 5,10,15-Tris(pentafluorophenyl) corrole (F15TPC) and its porphyrin analogue 5,10,15,20-Tetra(pentafluorophenyl)porphyrin (F20TPP) were investigated through the steady-state and the time-resolved transient spectroscopy. The results show a wide B band absorption peak for F15TPC, and a sharThe photophysical properties of 5,10,15-Tris(pentafluorophenyl) corrole (F15TPC) and its porphyrin analogue 5,10,15,20-Tetra(pentafluorophenyl)porphyrin (F20TPP) were investigated through the steady-state and the time-resolved transient spectroscopy. The results show a wide B band absorption peak for F15TPC, and a sharp peak for F20TPP. The Q band of F15TPC has two absorption peaks, while the F20TPP has four. The luminescence quantum yield and fluorescence life time for F15TPC and F20TPP are 0.15, 4.8 ns and 0.05, 11.1 ns, respectively. The F15TPC is characterized by high luminescence quantum yield and short fluorescence life time compared with F20TPP. The calculation results show that the F15TPC has large emission rate constant and nonemission rate constant. These may be ascribed to the changed electronic structure of the F15TPC chromophore for the lack of a fluorophenyl and its unsymmetrical and non-planar spatial structure..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2375 (2008)
Characteristics and Mechanisms of Corona Poling of Chromophore-Doped Polymers
Yun Binfeng, Hu Guohua, Lü Changgui, Zhou Hao, and Cui Yiping
The corona poling characteristics of the electro-optic polymer (chromophore DR19-doped PMMA) have been studied experimentally. The poling effects by poling parameters (voltage, temperature and time) on corona poling process have been analyzed by UV-Vis absorption spectroscopy and microscope. The electric fields inside The corona poling characteristics of the electro-optic polymer (chromophore DR19-doped PMMA) have been studied experimentally. The poling effects by poling parameters (voltage, temperature and time) on corona poling process have been analyzed by UV-Vis absorption spectroscopy and microscope. The electric fields inside the films increase with poling voltage, but the electric breakdown may occur with too high poling voltage. The chromophore orientation energy increases with poling temperature, but the phase separation may occur when the temperature higher than the vitrification temperature of polymer. The chormophere orientation increases with increasing poling time and reaches the dynamic balance at last. With increasing poling voltage, the order parameter which represents the poling effects increases to a maximum and then drops. Also the same trend of the order parameter has been obtained with increasing poling temperature. While the order parameter increases and reaches saturation with increasing poling time..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2379 (2008)
Crystalization Stability and Spectral Properties of Yb3+-Doped Alkaline Metal Modified Fluorophosphates Glasses
Dong Qinglei, Zhang Liyan, and Hu Lili
The influence of alkaline fluorides on spectroscopic properties and crystalization stability of Yb3+-doped fluorophosphate glasses was studied. Emission cross section of Yb3＋ is calculated based on reciprocity method. Results show that LiF increases the absorption and emission cross section and has optimal introductionThe influence of alkaline fluorides on spectroscopic properties and crystalization stability of Yb3+-doped fluorophosphate glasses was studied. Emission cross section of Yb3＋ is calculated based on reciprocity method. Results show that LiF increases the absorption and emission cross section and has optimal introduction amount, and the second is KF. Alkaline fluorides improve the crystalization stability of binary system and strengthen the glass network. Raman spectra show that YbF3 strengthens the glass network of binary system, but destroys that of the ternary system with alkaline fluorides and reduces the crystalization stability..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2383 (2008)
Fabrication and Transmittance Spectra of High Quality Three-Dimensional Photonic Crystals
Liu Guiqiang, Liao Yubo, and Liu Zhongmin
A facile pressure controllable self-assembly apparatus was designed, and perfect three-dimensional face-centered cubic(FCC) photonic crystals(PCs) were fabricated by using polystyrene colloidal micorspheres with diameter of 260 nm. The effects of pressures on photonic band gap depth and photonic band edge slope were anA facile pressure controllable self-assembly apparatus was designed, and perfect three-dimensional face-centered cubic(FCC) photonic crystals(PCs) were fabricated by using polystyrene colloidal micorspheres with diameter of 260 nm. The effects of pressures on photonic band gap depth and photonic band edge slope were analyzed and the optimal pressure condition(P=5999.5 Pa) for PCs growth was confirmed. Three photonic crystals were fabricated once and their transmittance spectra were measured. The transmittance spectra measured at different positions of the same PC and different PCs are similar. Fabry-Pérot oscillations appear at both sides of the main transmittance valley. PCs fabricated by this experimental apparatus are uniform, similar and highly ordered in the long-range crystal orientation and large areas. The experimental apparatus can be used to fabricate PCs in small-batch..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2400 (2008)
Properties of a One-Dimensional Confined Antiferromagnetic Photonic Crystal
Song Yuling, and Wang Xuanzhang
Band structures and transmittance of a one-dimensional confined antiferromagnetic photonic crystal were calculated by the transfer matrix method. Besides photonic band gaps, the results demonstrate the existence of another type of frequency gaps which principally depends on the antiferromagnetic resonant character and Band structures and transmittance of a one-dimensional confined antiferromagnetic photonic crystal were calculated by the transfer matrix method. Besides photonic band gaps, the results demonstrate the existence of another type of frequency gaps which principally depends on the antiferromagnetic resonant character and the confined dimension. In the vicinity of the antiferromagnetic resonant frequency, a relatively wider frequency gap can be obtained by properly changing the antiferromagnetic anisotropic-axis orientation and the confined dimension. It is about 15 times wider than that of bulk antiferromagnetic material. On certain conditions, the confined photonic crystal can be transparent in the frequency gap of corresponding bulk antiferromagnetic material for some discrete modes. The typical transmission spectra are presented and agree with the calculated band structures..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2404 (2008)
Optical Design and Fabrication
Monte Carlo Simulation Model of Micro Light Beam Solidification
Wang Xiang, Pei Xiangtao, Shao Peng, and Huang Wenhao
Light solidification is a photochemical reaction between the light beam and photosensitive resin, and has a direction relation with light solidification micro-machining resolution. First of all, the movement trajectory of photon in the resin was traced by Monte Carlo simulation. By sampling the exposure photon in the iLight solidification is a photochemical reaction between the light beam and photosensitive resin, and has a direction relation with light solidification micro-machining resolution. First of all, the movement trajectory of photon in the resin was traced by Monte Carlo simulation. By sampling the exposure photon in the incident and transmission processes, micro light beam solidification model was constructed based on photon transportation theory. Secondly, optical parameters of the resin were reconstructed by combining the genetic algorithm and the curing results of experiment. Finally, the simulated calculation of single-point curing process (λ=365 nm), shape and size of solidified points was carried out, and the as-obtained curing rule was analyzed in different exposure energy. The simulation results agree well with the experimental results under same exposure parameters. Thus the model can effectively simulate the complicated process of the reaction between the micro beam light and the resin, predict the curing result with different curing conditions and provide a foundation for studying micro solidification mechanisms, and optimizing the technique..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2388 (2008)
Optics at Surfaces
Numerical Study on Effect of Silicon Texture Structure on Reflectance of Light
Qiu Mingbo, Huang Yinhui, Liu Zhidong, Tian Zongjun, and Wang Wei
The light trap on texture of silicon wafer surface makes the light reflect many times when it enters, and declines energy loss of light, and different structure of light trap produces different transmission path which makes a different effect of light reflectance. To study how structure of light trap and incident angleThe light trap on texture of silicon wafer surface makes the light reflect many times when it enters, and declines energy loss of light, and different structure of light trap produces different transmission path which makes a different effect of light reflectance. To study how structure of light trap and incident angle affect reflectance of light, a numerical method was proposed. Every light transmission process was tracked and then the weighted coefficient of reflectance of all lights was calculated. Subsequently the anti-reflection of complex texture with different incident angle was obtained, and a reasonable advice for change of process parameter was given, providing a theoretical basis for fabricating efficient texture. If the size of light traps is less than the wavelength of incident light, the reflection is specular, and the light trap is seen as smooth. Weighted coefficient of reflectance was got by calculating and analyzing different incident angle on light trap with aspect ratio, depth, and density of light trap, then ideal structure on fabric surface was proposed, and the incident angle with the best reflection effect was got. At the end, weighted coefficients of reflectance of two classic textures by alkaline corrosion and electrical discharge machining were calculated, and the validity of this method was proved by experimental measurement..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2394 (2008)
Physical Optics
Solar Light Pipe Combined with Photocatalysis to Decompose Formaldehyde under Sunny Conditions in Summer in Beijing
Wu Yanpeng, Wang Xiaodong, and Ma Chongfang
Solar light pipe combined with photocatalysis could introduce sunlight into rooms and also has air purification function. The length of the solar light pipe is 0.55 m with a diameter of 0.28 m. The average ratio of reflection of the surface of solar light pipe is 0.82. Snow shaped astigmatism board has a diameter of 0.Solar light pipe combined with photocatalysis could introduce sunlight into rooms and also has air purification function. The length of the solar light pipe is 0.55 m with a diameter of 0.28 m. The average ratio of reflection of the surface of solar light pipe is 0.82. Snow shaped astigmatism board has a diameter of 0.28 m. Coating DegussaP25 solution evenly on the rugged side for the quality of 1.75 g. The experiments show that when the coating side away from the sun the lighting degree may be reduced compared with when facing the sun. But the average reduction was only 3.03 percent which would not have a significant impact on indoor lighting. The experiments also show that in a sunny summer morning under the direct sun, Solar light pipe combined with photocatalysis could reduce formaldehyde in a little box of 0.1 m3 volume from 1.0×10-6 to 0.19×10-6. Under the direct noon sun within 1h formaldehyde volume from 1.0×10-6 down to 0.17×10-6 with faster and more complete degradation of formaldehyde. In direct afternoon sun within 1 hour, the volume fraction of formaldehyde reduced from 1.0×10-6 down to 0.2×10-6. The rate of degradation in the afternoon was slower than that in the morning and noon, but also achieved a good performance..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2408 (2008)
Quantum Optics
Ground-State Lifetime of Strong-Coupling Bound Magnetopolaron in Asymmetrical Quantum Dot
Li Zhixin, and Xiao Jinglin
The properties of bound magnetopolaron with strong electron-LO phonon coupling were studied using a linear combination operator and a unitary transformation method in an asymmetry quantum dot. The ground state energy of strong-coupling bound magnetopolaron was obtained in an asymmetry quantum dot and the effects of theThe properties of bound magnetopolaron with strong electron-LO phonon coupling were studied using a linear combination operator and a unitary transformation method in an asymmetry quantum dot. The ground state energy of strong-coupling bound magnetopolaron was obtained in an asymmetry quantum dot and the effects of the transverse and longitudinal confinement lengths of quantum dot, the ground state energy of magnetopolaron , the electron-phonon coupling strength and the external temperature on the ground state lifetime of magnetopolaron were discussed. Quantum transition which causes the changes of the magnetopolaron lifetime is occurred in the quantum system due to the electron-phonon interaction and the influence of external temperature which is the magnetopolaron leap from the ground state to the first-excited state after absorbing a LO-phonon. Numerical calculations are performed and the results show that the ground state lifetime of bound magnetopolaron is extended with the rise of the ground state energy, and shortened with the electron-phonons coupling strength, the transverse and longitudinal confinement lengths of quantum dot , and the external temperature..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2416 (2008)
Rapid Communications
Aperture-Synthesizing Experiment of a Down-Scaled Synthetic Aperture Imaging Ladar
Zhou Yu, Sun Jianfeng, Luan Zhu, and Liu Liren
A down-scaled synthetic aperture imaging ladar (SAIL) is designed to simulate the condition of the far-field diffraction on the table of laboratory, and the techniques to monitor the qualifications of wavefront and heterodyne are developed, As a result, a target point is imaged along the azimuth direction with apertureA down-scaled synthetic aperture imaging ladar (SAIL) is designed to simulate the condition of the far-field diffraction on the table of laboratory, and the techniques to monitor the qualifications of wavefront and heterodyne are developed, As a result, a target point is imaged along the azimuth direction with aperture synthesizing. The experimental results are identical with the theoretical predictions..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2446 (2008)
Remote Sensing and Sensors
Optical Radiance Characteristics of Sea Fog Based on Remote Sensing
Hao Zengzhou, Pan Delu, Gong Fang, and Zhu Qiankun
For sea fog events auto-monitor from satellites, the visible and infrared spectral radiance characteristics of sea fog, water surface, and cloud regions are analyzed based on data analysis from AVHRR3/NOAA17 observations. The remote-sensing optical radiance characteristis of sea fog are analyzed. It is found that thereFor sea fog events auto-monitor from satellites, the visible and infrared spectral radiance characteristics of sea fog, water surface, and cloud regions are analyzed based on data analysis from AVHRR3/NOAA17 observations. The remote-sensing optical radiance characteristis of sea fog are analyzed. It is found that there exists obvious spectral difference between sea fog and others. In sea fog region, the satellite-measured reflectance relation of channel 3a (1.58～1.64 μm), channel 1 (0.58～0.68 μm) and channel 2 (0.725～1.0 μm), is RCh1>RCh3a>RCh2 and even RCh3a>RCh1>RCh2, which are different from the RCh1>RCh2>RCh3a of ocean and some cloud bodies. With the Streamer radiative transfer model, the fog and clouds spectral properties of AVHRR3 Channel 1, 2 and 3a are simulated under different fog/cloud microphysical and observational conditions. The simulations are consistent with observations. The reflectance of Channel 3a is affected by the size of particle, that is, the smaller is the size, the higher reflectance is. Finally, those fog and cloud spectral properties are explained with Mie scattering theory..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2420 (2008)
Thin Films
Design and Preparation of Narrowband Filter with Central Wavelength 121.6 nm in Vacuum Ultraviolet Region
Fu Lianxiao, Wu Yonggang, Zheng Xiuping, Wang Zhenhua, Peng Donggong, Jiao Hongfei, Cao Hong, Lü Gang, Zhou Hongjun, and Huo Tonglin
The narrowband filter with central wavelength of 121.6 nm is designed based on the double half-wave Fabry-Pérot interference filter, with peak transmittance of 6.783% and half-peak bandwidth is 10.7 nm. A filter with the peak wavelength of 217 nm is designed, prepared and measured, and optical constants and scale The narrowband filter with central wavelength of 121.6 nm is designed based on the double half-wave Fabry-Pérot interference filter, with peak transmittance of 6.783% and half-peak bandwidth is 10.7 nm. A filter with the peak wavelength of 217 nm is designed, prepared and measured, and optical constants and scale of film thickness are precise. The filter with central wavelength of 121.6 nm is prepared based on the 217 nm filter,the transmittance of filter is measured with the central wavelength of 120.74 nm, the peak transmittance of 5.94%, the half-peak bandwidth of 12 nm. The prepared filter is in accordance with prediction design in advance generally. At last the difference between experimental value and theoretical value is analysed..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2427 (2008)
Design and Fabrication of Al2O3/SiO2 Double-Layer Antireflection Coatings on 4H-SiC Substrate
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Al2O3/SiO2 double-layer UV antireflection coatings were designed and fabricated on 4H-SiC substrate, and the validity of theoretical design was further verified by scanning electron microscope (SEM) and reflection spectrum. The optimal physical thickness of Al2O3 and SiO2 is 42.0 nm and 96.1 nm respectively by programmAl2O3/SiO2 double-layer UV antireflection coatings were designed and fabricated on 4H-SiC substrate, and the validity of theoretical design was further verified by scanning electron microscope (SEM) and reflection spectrum. The optimal physical thickness of Al2O3 and SiO2 is 42.0 nm and 96.1 nm respectively by programming calculation. And then the minimum reflectance of 0.09% is obtained at reference wavelength λ=280 nm. According to error analysis, keeping the sum of double-layer thickness consistent with theoretical value is helpful to reduce the reflectance. In addition, the refractive index of SiO2 should more accurate and the refractive index of Al2O3 should be controlled close to 1.715 in the experiment. Al2O3/SiO2 double-layer coatings were deposited on 4H-SiC substrate by electron beam evaporation and the physical thickness is 42 nm and 96 nm respectively. SEM images show that the deposited layers and the substrate perform good adhesion to each other. The practical minimum reflectance is 0.33% at λ=276 nm which is close to theoretical value. Compared with conventional SiO2 single layer, Al2O3/SiO2 double-layer coatings show low reflectance and better wavelength selectivity. These results make the possibility for 4H-SiC based UV optoelectronic devices with Al2O3/SiO2 films as antireflection coatings..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2431 (2008)
Design of Homogeneous Thin Film Combining with Fourier-Transform Synthesis Method
Zhu Huaxin, Gao Jinsong, Wang Xiaoyi, Wang Tongtong, Chen Hong, Zheng Xuanming, Shen Zhenfeng, Li Xiangbo, Yin Shaohui, Liu Xiaohan, and Wang Shanshan
Based on the theory of Fourier-transform synthesis method, a minus filter on K9 substrate was synthesized. The gradient-index thin film with the desired transmittance character was synthesized by Fourier-transform synthesis method, but it is difficult to fabricate. So it was divided into many homogeneous coatings with Based on the theory of Fourier-transform synthesis method, a minus filter on K9 substrate was synthesized. The gradient-index thin film with the desired transmittance character was synthesized by Fourier-transform synthesis method, but it is difficult to fabricate. So it was divided into many homogeneous coatings with discrete refractive index. For the limited kinds of coating material, the thin film with arbitrary refractive index is not available. Based on the idea of two very thin high-low pair layers can be treated approximately as a thin layer with an average refractive index of the two layers, these coatings were replaced by homogeneous coatings. After optimization of simplex-law, the layers are composed by 183 layers of ZrO2 and SiO2. And the total thickness is 7.09 μm. The average transmittances in pass band and rejection band are 97.56% and 3.13%, respectively. And the optimizated result is better than that made with ununiform coatings and concides with the desired one. All these indicate that it is a feasible method to design coatings with any desired spectrum character, and it is possible to fabricate the coatings designed with Fourier-transform synthesis method in practice..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2436 (2008)
X-Ray Optics
Precision Controlling of KBA X-Ray Microscope
Zhao Lingling, Hu Jiasheng, and Sun Delin
KBA X-ray microscope is a grazing non-coaxial incident X-ray microscope. The front pair mirrors are not perpendicular to the back pair strictly, which brings much difficulty to the analysis of image quality. Thus general optical CAD program is not suitable to this kind of optical system. The co-axial spherical refrectiKBA X-ray microscope is a grazing non-coaxial incident X-ray microscope. The front pair mirrors are not perpendicular to the back pair strictly, which brings much difficulty to the analysis of image quality. Thus general optical CAD program is not suitable to this kind of optical system. The co-axial spherical refrective vector formulations are adjusted to establish the program for the non-coaxial grazing incident microscope, with which the aberrations and the synthesis errors are analyzed. The analytical results show that KBA microscope is a large aberration system. For an object distance tolerance of -0.4～1 mm, the grazing angle tolerance is -8″～0″, the separation angle tolerance of two mirrors is -20″～0″, and the change of dispersion spot is in an allowed range. This program is meaningful for the analysis and fabrication of KBA microscope..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue 12, 2441 (2008)
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