2015 Vol. 36, No. 3

OE System and Engineering
Laser radar launching/receiving optical system design for three-dimensional shape measurement
Zhang Xin-ting, Kang Lei, An Zhi-yong
2015, 36(3): 337-342. doi: 10.5768/JAO201536.0301001
A laser radar ranging system based on the Michelson interferometer was designed using the difference-frequency interference principle. The system can realize three-dimensional shape measurement with the shaft encoder.The design of the laser radar launching system and receiving system was introduced .For the launching system, according to the Gaussian collimating theory,the relevant parameters of the optical system were determined,and a laser ranging system used for 2m~18m range was designed. At the same time, the zoom curve was drawn by using Zemax macro programming. For the receiving system, the relevant parameters of target were determined based on the laser radar ranging equation to get the maximum energy of the echo, and the echo beam was coupled into the fiber through the optical system. This system realizes the launch and receive common-path. It can be used for noncontact measurement of bullet head face of railway vehicles and other complex three-dimensional faces. It has the features of high speed, high accuracy, and has very broad prospects for development.
Vision/INS integrated navigation for UAV autonomous landing
Cai Ming, Sun Xiu-xia, Xu Song, Liu Xi, Liu Ri
2015, 36(3): 343-350. doi: 10.5768/JAO201536.0301002
A vision/ inertial navigation system (INS) integrated navigation method was proposed to promote the accuracy and autonomy of navigation system for unmanned air vehicle(UAV) autonomous landing. Regarding the INS error equation as process model, and two-view geometry between projective points of identical feature in different instants as measure model, a nonlinear filter was built for INS error estimation. To expedite computation and avoid invalidity of unscented Kalman filter (UKF) algorithm, the square-root-UKF(SR-UKF) was used to estimate the INS error, and the navigation data was compensated by estimating result. Simulation results show that the proposed method is effective to improve navigation system accuracy, and able to reduce the error to 8% of INS.
Attitude algorithm design for light beam circumrotated on three-axiselectro-optical reconnaissance platform
Yin Jian, Gao Jiao-bo, Zhang Wan-lin, Chen Hong
2015, 36(3): 351-355. doi: 10.5768/JAO201536.0301003
When some three-axis electro-optical reconnaissance platform works, it needs using light beam to circumrotate on platform surface. In order to calculate the attitude of the light axis during platform working, the quaternion algorithm and coordinate transformation algorithm were adopted to solve this problem. Simulation results show that the two methods can both get better effect;however, the coordinate transformation algorithm has enormous computation and bad real time feature for using lots of trigonometric functions,while the quaternion algorithm has few trigonometric functions which is more easy for practice applications.
Application of speckle technique in laser homing guided weapon simulation system
Han Gang, Xu Ya-e, Shen Yang, Wang Jin, Wang Sen
2015, 36(3): 356-361. doi: 10.5768/JAO201536.0301004
The developing status of laser homing guided weapons was analyzed.By taking the semi-active laser homing guided projectile as the example and based on the summary of practical working experience ,the laser speckle technique theory was used innovatively to calibrate the optic system in laser homing guided weapon simulation system .After the researches and analyses, the consistency between the simulation and actual working environment was realized theoretically .Moreover,the feasibility was verified by productive practices and real target tests .It provides some practical significance and reference value.
Shipborne photoelectric rotary table design and feasibility analysisunder specific environment
Zhang Lei, Qiu Ya-feng, Cao Yuan
2015, 36(3): 362-368. doi: 10.5768/JAO201536.0301005
Combined with the technical requirements of shipboard photoelectric turntable, its mechanical structure was designed by pro/E software. According to the surface material of the turntable, the surface deformation vibration under special environment such as the equivalent marine static wind load, extreme temperature and vibration waves was analyzed by ABAQUS, in order to test the stress and strain of structure and ensure that the need of design accuracy for shipboard photoelectric turntable can be satisfied.Results show that the maximum stress point under the equivalent marine static wind load is 255 MPa which is less than the yield strength of steel(355 MPa); the maximum stress point under temperature difference is 174.8 MPa and 247.1 MPa, respectively, which are both less than the yield strength of aluminum alloy (274 MPa); the position of the maximum deformation of 1~5 vibration mode under vibrating waves are not near the vicinity of the shaft.
Illuminating source design of online visual inspection system for glass defects
Yuan Wei-qi, Bi Tian-yu
2015, 36(3): 369-375. doi: 10.5768/JAO201536.0301006
A method for automatic glass inspection on the production chain based on visual system was adopted. The method of illuminating is crucial to image in acquisition process,in order to avoid the illuminating jamming for judgment to guarantee the accurate identification result of different cracks by machine visual system, we carried out the research on the illuminating source system,including the luminous intensity,the wavelength and the position relative to line scan camera and glass which is on the production chain. We proposed a novel method of illuminating to achieve high quality image to solve problems caused by the influence of illuminating,with the analysis of influence between the defective part and the normal part when illuminating source system operates. It is proved that the method can realize realtime detecting to achieve accurate and reliable results,through a batch of glass samples tests. From the detection of glass image scanned under the condition provided by illuminating source system,the visual system can compute the defect and present the position size and depth,if the glass is not the acceptable product.
Optical design of wide-angle large-relative-aperture f-θ lens
Su Yang, An Zhi-yong, Li Qi, Xu Miao
2015, 36(3): 376-380. doi: 10.5768/JAO201536.0301007
The f- lens is an important essential component in laser scanning systems. For the shortcomings of current domestic laser scanning systems such as small working surface , slow measuring speed , low measurement accuracy, a large field of view(FOV) f- lens was designed with large relative aperture to improve the working efficiency. The designed lens is a negative distortion lens with the image space telecentric optical path. Expected parameters are as follows: 2=60,D=120 mm,f=500 mm. After calculation, the Zemax software was used to optimize the design for f- lens model. Finally ,a large-working-area large-relative-aperture f- lens was obtainde with an Airy disk diameter of 3.514m, a scanning range of 500 mm500 mm and an aperture of 6/25. The image is clear, the optimization results achieve the expected design target.
LED direct backlight lens design based on modulation of paraboloid inner surface for uniform illumination
Meng Die, Zhang Rong-fu, Yu Hao
2015, 36(3): 381-385. doi: 10.5768/JAO201536.0301008
In the system of near-field uniform lighting, lens design methods commonly use sphere as the inner surface, and the calculation of the free-form surface only considers primary reflection . But when the angle reaches a certain scope, total reflection on the free-form surface of the lens is easy to occur ,which will lead to the poor illumination performance. In order to get the larger light distribution in the near-field lighting system ,a free-form lens design method based on the modulation of the parabolic inner surface was proposed. The parabolic can diffuse the energy of the light source, and then calculate the free-form surface. Through simulation, the uniform light spot with 40 mm radius can be realized at 15 mm distance away from light source, while the uniformity reaches 95%, the efficiency reaches 97.8%. Comparing with traditional direct lens, the uniformity is enhanced and the height of backlight box is decreased by using the structure of this lens.
OE Information Acquisition and
Multi-target detecting algorithm based on digital image
Wang Chao, Ji Ming, Wang Jiao-ying, Jiang Wen-tao, Xie Jing, Li Tao, Gao Ya
2015, 36(3): 386-390. doi: 10.5768/JAO201536.0302001
In order to improve the capacity of weapons system to attack multiple targets precisely at the same time, the multi-target tracker can be used to assist laser and servo platform to capture and track multiple potential targets in electro-optical system. A novel multi-target detecting algorithm run in multitarget tracker was studied. According to the difficulty of processing timely in embedded system for the high resolution of digital image and mountainous data flow, based on TMS320C6455 digital signal processing (DSP), a global optical flow estimate image mosaic algorithm based on wavelet pyramid decomposition was proposed to achieve background compensation in moving image to get difference image.Compared to traditional block matching, gray-scale projection matching and key-points relevant matching algorithm, the new method is more accurate and timely running. Region growth combined with tunnel filter algorithm was carried out to acquire multiple final targets in difference image. The experiment verified that the method can achieve 95% detection rate and cost only 25 ms for automobile, bicycle and pedestrian in complex ground, which has good real-time performance and detecting effect.
Object tracking based on background-weighted spatial histogram
Liu Fang, Yu Wang-sheng
2015, 36(3): 391-397. doi: 10.5768/JAO201536.0302002
In order to improve the feature robustness of the traditional object tracking algorithm, an improved algorithm based on background-weighted spatial histogram was proposed. It combines the background-weighted histogram and spatial histogram and exploits the advantages of both features, which distinctively improves the feature robustness. The proposed algorithm was implemented under the framework of Mean Shift tracking and obtained a stable tracking. Experimental results indicate that the proposed algorithm can well track the object and obtains at least 80% decreasing of the mean center location error than that of the traditional algorithms.
Video optical encryption technology based on liquid crystal light valve
Wang Hong-wei
2015, 36(3): 398-402. doi: 10.5768/JAO201536.0302003
Encrypted transmission of high-definition video surveillance is an important researching area, but with the continuous improvement of the clarity of the video image, the existing video encryption algorithm is facing a severe test. Therefore, we explored the feasibility of using optical encryption and decryption for video transmission, proposed the single-channel video optical encryption technology based on liquid crystal light valve and double random phase encoding. This technologys time consuming of encryption and decryption was almost zero,which could greatly improve the performance of video transmission. Additional, due to the optical encryption technology was used only in the front end and the end of the existing video transmission link, and did not involve video coding and transmission, the availability and versatility of the system could be enhanced. At last, the method was simulated by using Matlab software. The results show that the encrypted image of each channel is close to white noise,so it is almost impossible to recover the original image. Meanwhile, after decryption, the image can be completely restored. Therefore, this method has broad promotion and application value in the growing popularity of high-definition video in the future.
Decolorizing of infrared pseudo color image
Yang Chen, Zhang Zhi-yong, Wang Ji-hong, Huang Yu-yang, Ding Zhao
2015, 36(3): 403-407. doi: 10.5768/JAO201536.0302004
Considering the human eyes- perception capability, the pseudo color coding technology is usually adopted to colorize the output gray image of infrared systems. Comparing to gray images, computers need more memory and calculation to process color images. Since some infrared equipments only provide pseudo color images,the grayscale conversion of pseudo color image was studied. Besides the 3 common algorithms, maximum decomposition, average and luminance, a decoding method was presented to decolorize infrared images. Based on the 2 kinds of methods above, decolorizing for both linear and sinusoidal nonlinear pseudo color images were studied in experiment; furthermore, image quality was also compared. The experiment result demonstrates that the decoding method is a kind of lossless algorithm for linear pseudo color image with 0 mean squared error. For sinusoidal nonlinear algorithm, loss due to quantization errors are inevitable, it still has a quite low mean square error (0.309 4) and high peak signal noise ratio (101.356 0).
Optical Metrology and Measurement
Optimization scheme design on construction of cryogenic radiometer
Pang Wei-wei, Zheng Xiao-bing, Li Jian-jun, Wu Hao-yu, Shi Xue-shun
2015, 36(3): 408-414. doi: 10.5768/JAO201536.0303001
The Brewster window of traditional cryogenic radiometer has a great influence on the accuracy of absolute spectral responsivity calibration of standard transfer traps. In this paper, the traditional calibration for standard transfer trap was introduced. The reasons of precision degradation due to Brewster window and its state repeatability were analyzed, based on which a novel calibration scheme was proposed. The cryogenic radiometer and standard transfer trap were assembled on a concentric orbit and manipulated by an accurately electromechanical driving mechanism. By alternately switching the two instruments into calibration optical path, the absolute calibration for a standard transfer trap against cryogenic radiometer could be carried out. The new calibration system could completely eliminate the influences caused by Brewster window, would reduce about 50% uncertainty of laser power measurement and further reduce the uncertainty during the calibration process, which is of great significance in improving the accuracy of radiometric calibration.
Influence of double-pump light on sensitivity of all optical Cs atomic magnetometer
Liu Qiang, Zhang Xiao-yu, Liu Chao, Fu Tian-shu, Liu Dong-ming, Sun Jian, Xia Chang-chao
2015, 36(3): 415-419. doi: 10.5768/JAO201536.0303002
Atomic polarizability can influence the sensitivity of atomic magnetometer. As the buffer gas of Cs vapor cell was about 13 332.2 Pa, the two pump light frequencies were locked toF=4F=3 and F=3F=4 of Cs D1 transition respectively, the population dynamics of the magnetic sublevels of ground states and excited states were calculated. We find that with the sustained action of pump light ,the population of F=3 and F=4 are pumping to |F=4,mF=4, and the polarizability reaches maximum value. At the same time the signal-noise ratio of experimental result increases effectively by using two pump beams, then the sensitivity of atomic magnetometer increases by 34%.
Monocular measurement for object-s attitude based on vanishing point theory
Zhang Song, Xie Yong-jie, Zhang Hua-liang, Zhao Yan
2015, 36(3): 420-423. doi: 10.5768/JAO201536.0303003
A novel monocular method for objectvs attitude measurement based on vanishing point was proposed, which used parameters of monocular camera and the location of vanishing point in the image to compute the direction of characteristic straight line and object-s attitude. Meanwhile, vanishing point accuracy evaluation index was presented, which could be used as evaluation criterion of attitude measurement accuracy and weight factor for weighting fusion. The feasibility and accuracy of the proposed method were tested by experiments with simulated data and real images.Results show that it is an accurate and easy method for attitude measurement of columnar objects.The mean-error between this paper and the axes-symmetry method is less than 0.2.
Support vector machine based distributed optical fiber leakage detection system and experimental analysis
Huang Yue, Wang Qiang, Han Ling-juan, Zhu Jun
2015, 36(3): 424-429. doi: 10.5768/JAO201536.0303004
Leakage experiments were performed on the distributed optical fiber pipeline leakage detection system. The system was based on a mixed interference principle of Mach-Zehnder and Sagnac. 20 groups of leakage point samples were gained between 1km to 9km from the leakage experiments. Support vector machines(SVMs) were used to build the sample of data model, the related parameters of SVM were optimized , and the sensitivity of the system was analyzed. The results show that the processed samples are significantly closer to the actual leakage points than the experimental leakage points through regression analysis. The mean absolute error of experimental leakage points is 118.85m while that of the regression samples is 92.01m. The accuracy rate of positioning improves to 99.85%. The sensitivity of the detection system is lower when the leakage points are farther away from the Faraday rotation mirror. The sensitivity of the system is less than 0.5 Hz / m when the leakage points are over 10 km.
LLL Night Vision Device and Im
Triple-band low light level color night vision technology
Chen Yi-chao, Hu Wen-gang, Wu Dong-sheng, He Yong-qiang, Zhang Dong-xiao, Li Xiao-ming
2015, 36(3): 430-434. doi: 10.5768/JAO201536.0304001
In order to overcome the defect that low-night vision device generates monochrome images and to get visual color images more consistent with human eyes, according to the red-green-blue (RGB) color model and spectral separation principle of filters, a system of color night vision based on the secondgeneration image intensifier was designed. Through measuring the spectral transmittance of filter, the impact of filter on the signal to noise ratio(SNR) of image intensifier was educed. According to the low SNR problem, a four-frame fused method of full-wave image was proposed and verified by experiments .The experimental results show that the entropy and variance of chamber image are 6.8 and 35.39, respectively, and that of outdoor image are 7.0, 45.07, respectively, which are all better than the corresponding values of three-frame fused image. The result proves that the method presented is able to overcome the defect of low SNR, and get clearer color night vision image with more details.
Design and experiment for polarization imaging system of low-light-level image intensifier
Ru Zhi-bing, Liu Bing, Li Shuang-quan, Zhang Xiao-liang, Zou Cheng-shuai, Zhang Qi-xian
2015, 36(3): 435-441. doi: 10.5768/JAO201536.0304002
In order to validate the feasibility that low-light-level(LLL) image intensifier achieves polarization imaging,according to polarization imaging theory, the LLL polarization imaging system was designed based on time-sharing polarization imaging technology. A 3rd generation image intensifier and a high dynamic range charge coupled device (CCD) were selected, a big dimension aperture objective lens and a relay lens were designed. The high transmissivity and high modulated transfer function (MTF) were achieved on image coupling. A digital CCD and a digital frame capture circuit with an embedded image process module were used. The correlative software about the image process was accomplished, so that the polarization imaging experiment was accomplished for the human target and the natural background in lab and field. The test results show that the contrast of the human target to natural background is 1.35 by the conventional imaging way, and is 2.35 by the polarization imaging system of LLL image intensifier, the contrast of the human target to the natural background is improved by LLL polarization imaging technology at night.
Technical index of ultraviolet sensor used for detecting shooting
Liu Zhen-ji, Chu Sheng, Yang Yong-hui, Liu Jin, Yuan Xiao-bing
2015, 36(3): 442-447. doi: 10.5768/JAO201536.0304003
A standard-type blind ultraviolet(UV) detection sensor was used to conduct the experiment of detecting on the flames shooting, the experimental data was analyzed . The technology index of the UV sensor which was depended on to detect shot flame spectrum was proposed, by combining with ultraviolet light transmission characteristics. In order to detect the rifle firing away from 1000m without the considering of the incident angle and response time of the sensor, the response rate and response area product of the UV sensor should achieve at least 0.002 AW-1m2, then the response current of sensor is up to 100nA which can be obviously detected. According to a prototype scheme of gun-shot detection device, the technology indices of the UV sensor was analyzed, such as transmittance, the feature of solar blind, UV responsivity , incident angle and short circuit,etc. The molecular beam epitaxy was used to prepare a kind of MgZnO UV detection sensors, and furthermore, its transmittance, ultraviolet spectrum response rate and response time were measured. After further optimization of performance, it is expected to meet the requirements of shot detection.
Optical Element and Fabrication
Rapid microfabrication technology based on digital lithography projection system
Zhang Ya-ya, Cui Jian-guo
2015, 36(3): 448-453. doi: 10.5768/JAO201536.0305001
To design a cost-effective microfluidic chip-s processing method, which can quickly fabricate different size micro-channels on polydimethylsiloxane (PDMS) surface, we used the method depending on the imaging principle of commercial digital projector, carried on the simple configuration, and then got a reduced image named as digital lithography projection system (DLPS), which could be used to fabricate the micro-channel on the PDMS surface.Moreover, through lotus leaf effect and capillary adsorption effect experiments, the processing performance of DLPS was verified and applied. Results show that the DLPS can process microstructure on PDMS surface, the minimum stable machining precision can reach 40 m, through the simulation of lotus leaf effect ,the material surface-s hydrophobic angle is 1233. The DLPS can be used for rapid processing of microfluidic chip, and when the channel size is not very strict, this low-cost and high-efficiency can make the system completely suitable for general laboratory.
Error compensation for trim puncher based on rapid super-resolution measurement
Ye Su, Ye Yu-tang, Liu Juan-xiu, Liu Lin, Du Chun-lei
2015, 36(3): 454-459. doi: 10.5768/JAO201536.0305002
To eliminate the punching error of the flexible printed circuits(FPC) caused by the deformation of the films during the running time of the trim puncher, we used the images of the target after punching to measure the distance between the dies and the punching edge, and calculated the error of the system in order to do error compensation. The experiment results demonstrate that, after error compensation, the root-mean-square error of the punching position, respectively, reduces by 41.6% and 17.0% in X-direction and in Y-direction, the process capability index of system is 1.6118. We used film to extend the dimensions of the FPC production and increase the useful area of the production, so that the cost of production could decrease. The proposed rapid superresolution measurement, without using image registration, enable to reduce the position error of image edges from 0.5 pixels to 0.25 pixels. The error compensation used in this study can reduce the error of punching position caused by running a production for several hours. The proposed system is capable of satisfying the precision requirements of FPC punching.
Calculation on optical path difference of oscillating Fourier transform spectrometer
Liu Ri-long, Liu Mu-hua
2015, 36(3): 460-462. doi: 10.5768/JAO201536.0305003
The optical path difference is an important character in Fourier transform spectrometer, and the optical path difference is produced by means of moving mirrors in spectrometer. Based on the scanning interference spectroscopy principle, the optical path difference of the spectrometer was analyzed theoretically ,and its calculation expression was given .Results show that the optical path difference is approximately proportional to the swing angle.Additional , the optical path differences between beams of light associated with different incident angles were also pointed out. The studies pave the way for optimization design of Fourier transform spectrometer.
Misalignment of KTP crystal in frequency-doubled laser
Li Xiao-ming, Shen Xue-ju, Li Gang, Liu Xun
2015, 36(3): 463-468. doi: 10.5768/JAO201536.0305004
In allusion to the most commonly used KTiOPO4 (KTP) frequency-doubling crystals, the influence of tilting misalignment and rotary misalignment on conversation efficiency in frequency-doubled laser was discussed. Based on the principal axis coordinate transform, the model of tilting misalignment was established, what-s more, the process of tilting and rotary misalignment was analyzed in detail theoretically and experimentally. The results show that, in the case of tilting misalignment, two different narrow peak values of conversion efficiency appear with the variation of directions, and the bigger tilting misalignment value, the smaller included angle of peak value direction, in other direction, the conversion efficiency is zero; for rotary misalignment, type-Ⅰ and type-Ⅱphase matching conversion efficiency vary with misalignment angle for and /2 cycles, respectively.The results may provide a promising route to the design of frequency-doubled laser.
Laser Technology
Study on reflective adjustable laser attenuator
Xue Zhan-li, Yu Bing, Wu Pei, Han Zhan-suo, Qin Yan, Chen Juan, Li Hong-guang
2015, 36(3): 469-474. doi: 10.5768/JAO201536.0307001
Based on the principle of reflected polarized light with various reflectances when it enters on dielectric interface at different oblique incidence angles, an adjustable laser attenuator working at 1 064 nm wavelength was designed, with 6 angle accurate, 100 W/cm2 (continuous-wave) and 0.1 J/cm2 (10ns pulses) damage threshold. The transmittance of attenuator was measured,the range of transmittance was 8.510-5~1. And the effect factors for propagation beam quality caused by attenuator were investigated. Finally, the suggestion for improving the performance of the attenuator was discussed.
Experiment study on jamming and damage thresholds of polycrystalline silicon detector irradiated by CW CO2 laser
Wang Dong, Zhang Heng-wei, Qin Xiao-hu, Zhang Yan-xiu, Wang Fei
2015, 36(3): 475-479. doi: 10.5768/JAO201536.0307002
In our experiment, polycrystalline silicon detector was irradiated by 10.6 m continuous-wave(CW)CO2 laser, and the saturated threshold and damage thresholds were determined, the achieved saturation threshold and damage threshold were 5.5510-4 W/cm2 and 0.48 W/cm2, respectively. The jamming effectiveness and damage mechanism on polycrystalline silicon detector of different laser power densities and different laser irradiation time were analyzed, and according to the jamming degree of detector, the interference hierarchy was classified as 4 grades, such as point saturation, moderate saturation, severe saturation and point damage .Additional, based on the relationship between the interference laser power and the interference light spot area, the relational expression of power function y=76.3x0.29 was got, and finally according to this, the jamming effect of 10.6 m pulse laser on infrared imaging system was discussed.
Fiber Sensing and Optical Communication
Design of optical fiber data link simulator
Yin Hong-bo, Lin Xiao-juan, Wang Zhen-xing, Yin Hai-lin, Wang Bing, Liu Dan, Wang Xiao-ting
2015, 36(3): 480-485. doi: 10.5768/JAO201536.0308001
In order to analyze the fiber changes of the optical- fiber guidance missile in flight and meet the needs of the missile static and dynamic simulation,a device that can simulate data link transmission loss characteristics of optical fiber was designed. The dynamic and static models of system transmission loss were established. Using the optical simulator,the channel interference,dynamic loss,data delay,etc, that may occur in the missile flight were implemented.The experiment results show that the interference range of optical signal is -50 dBm~-40 dBm, the delay range of optical signal transmission is 16.65 s~99.9 s,the adjustment range of simulator dynamic loss is 0 dBm~50 dBm.The performance verification of optical fiber transmission system can be realized.
Power conversion efficiency analysis of distributed backward pumped fibre Raman amplifier
Long Qing-yun, Hu Su-mei, Peng Zhi-ping
2015, 36(3): 486-491. doi: 10.5768/JAO201536.0308002
der to analyze the power conversion efficiency of backward pumped fibre Raman amplifier(FRA), by combining the shooting method with the RungeKutta method for solving differential coupling equations of backward pumped FRA, the effect of every parameter on backward pumped FRA-s power conversion efficiency was detailedly investigated. It is found that the power conversion efficiency is increasing with the increase of fibre length, until it reaches the maximum; the power conversion efficiency increases when the initial signal power or Raman gain coefficient or the attenuation coefficient of signal is larger, and it decreases when the fibre efficient area or the attenuation coefficient of pump or the pump and signal frequency ratio is larger; the relation between power conversion efficiency and initial pump power is para-curve. The conclusions are helpful to,further study the backward pumped FRA.
Birefringent crystal-clad fiber-optic polarizer based on fused biconical taper
Zhao Hai-jun, Xie Liang-ping, Cao Yang, Dong Cai-xia, Wang Shao-hua, Zhang Jia-quan
2015, 36(3): 492-496. doi: 10.5768/JAO201536.0308003
A simple model was established, the polarization extinction ratio(PER) expression of cystalclab fiber-optic polarizer was presented based on geometrical optics. The variation of the PER versus the diameter of biconical taper waist and the length of cladding was analyzed. Considering the intensity of biconical taper waist, the manufacturing parameters of polarizer were optimized and analyzed,corresponding experiment was carried out. The experiment verifies that the PER is more than 30 dB and its insertion loss(IS)is less than 0.5dB. The variation of the PER is less than 1.5dB and the variation of the IS is less than 0.5dB in the temperature range of -50 ℃~+70 ℃. This kind of polarizer is fine in tempreture performance and stability.