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Issue 3 ， 2005
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Theoretical analysis of 980 nm high power vertical external cavity surface emitting semiconductor laser (VECSEL)
Abstract：By using period resonance gain structure, a laser diode (LD) pumped 980 nm vertical external-cavity surface-emitting laser (VECSEL) with active region of InGaAs/GaAsP/AlGaAs system was developed. The longitudinal confinement factor, threshold gain, optical gain and output power were calculated. The characteristic parameters of VECSEL were optimized, and the structure of VECSEL was designed. The results show that the output power of a LD-pumped VECSEL can be larger than 1.0 W based on the theoretical calculations.Keywords：vertical external-cavity surface emitting laser;diode laser pumping;longitudinal confinement factor;optical gain- 56
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Published：2020-08-12 -
Blue light laser by direct frequency doubling of VCSEL
Abstract：A 980 nm vertical cavity surface emitting(VCSEL) laser realizes frequency doubled by directly doubling and compound cavity doubling and obtains 490 nm blue laser. GRIN lens are used for shaping beam and LBO crystal is employed for secondary harmonic generation(SHG). In the experiment, the output power of the fundamental frequency laser is 530 mW,Gauss beam is adjusted by one GRIN lens with a length of 0.23p@980 nm and a LBO crystal with dimensions of 2 mm×2 mm×5 mm. And 490 nm blue beam of 50 μW is obtained. By adding an external cavity mirror with a radius curvature of 50 mm,the output power of 490 nm blue beam is increased to 70 μW.Keywords：vertical cavity surface emitting laser;direct frequency doubling;compound cavity;LBO crystal;GRIN lens;secondary harmonic generation- 69
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Published：2020-08-12 -
All-solid-state continuous-wave doubly resonant all intra-cavity sum-frequency laser at 589 nm
Abstract：A resonator designed for doubly resonant continuous-wave intra-cavity sum-frequency mixing (SFM) laser is studied. Nd:YVO4 and Nd:YAG are pumped by two Laser Diode Array (LDA) which were coupled by optical fiber respectively, 1 064 nm wavelength is obtained from 4F3/2-4I11/2 transition in Nd:YVO4 and 1 319 nm wavelength is obtained from 4F3/2-4I13/2 transition in Nd:YAG. Both laser beams are oscillated in two sub-cavity, and a KTP with type II Critical Phase Match (CPM) is used at the overlap of the two fundamental laser beams to realize the 589 nm SFM laser. An output power of 340 mW continuous-wave TEM00 yellow laser could be obtained with 8 W/14 W pump power. The output power is with low noise and a M2 factor of less than 1.2. The power instability is less than ±3％ within 4 h. Doubly resonant is an effective solution to realize 589 nm all solid state yellow laser pumped by LDA.Keywords：laser diode array;sum-frequency;all-solid-state laser;yellow laser- 42
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Published：2020-08-12 -
Nonlinear optical properties of ZnO films deposited by metalorganic chemical vapor deposition (MOCVD) technique
Abstract：The nonlinear optical properties of ZnO thin films deposited by metalorganic chemical vapor deposition (MOCVD) technique are investigated. ZnO films are deposited on sapphire substrates at 200~500 ℃. XRD and SEM are used to investigate the crystalline quality. 1.06 μm wavelength beam output from a Nd:YAG laser is used as fundamental beam. The second-order and third-order susceptibility is studied. By comparing the second harmonic signal generated in a series of ZnO films with different growth temperatures, we conclude that a significant part of second harmonic (SH) signal is generated at the film deposited at appropriate temperature. The dependence of SH on the deposited temperatures is discussed. The second order susceptibility tensor χ (2)zzz=9.2 pm/V and third-order susceptibility χ(3) = 5.28×10－20 m2/V2 are deduced for a film deposited at 250 ℃.Keywords：second harmonic generation;metalorganic chemical vapor deposition (MOCVD);second order susceptibility;third order susceptibility;deposition temperature- 33
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Published：2020-08-12 -
Experimental study of the spectrum at 11~20 nm of a laser-produced plasma source using water target
Abstract：A laser- produced plasma(LPP) source is built with water as target and a Nd:YAG laser as irradiate laser, the radiation of the LPP source at 11~20 nm is measured with an AXUV100 silicon photodiode combined with a McPHERSON model 247 grazing incidence monochromator, of which the monochromator resolution is Δλ≤0.075 nm, and the wavelength scanning interval is 0.5 nm. The experimental result demonstrates that the water target LPP source has EUV emission at 11~20 nm wavelength, which are all generated from electronic transitions in oxygen ions. In addition, to solve the erosion problem caused by the short distance between the laser-water action point and the nozzle, the distance is lengthened by heating the nozzle to reduce the effect caused by the evaporation and the adiabatic expansion.Keywords：laser-produced plasma source;spectral measurement;Soft X-ray;water target- 35
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Published：2020-08-12 -
Double-nozzle piezoelectric servovalve
Abstract：To improve the static and dynamic characteristics of traditional electrohydraulic servovalves, a new type electrohydraulic servovalve was designed by using piezoelectric actuator based on bimorph instead of the moment motor of conventional servovalves. The results show that the output distance of designed piezoelectric bimorph actuator is 82.5 μm, fluctuation in full scale is less than 0.7μm, and resonance frequency is 1.2 kHz. It can meet the requests of servovalve. And the designed servovalve owns perfect linearity when the frequency is less than 100 Hz. The lacks of traditional electrohydraulic servovalves in bandwidth and anti-electromagnetic ability have been overcome.Keywords：electrohydraulic servovalves;piezoelectric bimorphs;feedback control- 36
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Published：2020-08-12 -
Piezoelectric driven micromanipulator and its positioning accuracy analysis
Abstract：A micromanipulator driven by piezoelectric bimorph was developed to assemble micro parts 20~200 μm in size. The manipulator closes about 200 μm while a driven voltage of 80 V is applied. The diameter of grasping arm tips is about 15 μm. The release positioning accuracy is analyzed with a theoretical model and the methods to obtain high position accuracy are discussed. A positioning accuracy of 2 μm is achieved while a 170 μm diameter polymer sphere is released in humid environment (RH=50%). The manipulation experiments indicate that the micromanipulator could pick, transfer and release micro parts with a satisfactory positioning accuracy.Keywords：micromanipulator;positioning accuracy;piezoelectric bimorph;adhesion force- 63
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Published：2020-08-12 -
Novel sophisticated stepping linear piezoelectric actuator
Abstract：A novel sophisticated stepping linear piezoelectric actuator was designed based on piezoelectric stack as actuator element. Because of used unique double symmetric anchoring/loosing, tolerance clearance between anchoring/loosing and runner is modulated precisely by using oblique blocks, meanwhile, applying flexible structure of overall structure processing ensures stability and accuracy of actuator. Mechanical properties of the stepping linear sophisticated piezoelectric actuator are analysed with finite element method and a number of experiments were carried out. The results of test suggest actuator has a resolution of 40 nm, travel of 18 mm, velocity of 6 mm/min and loading capacity of 150 g.Keywords：linear actuator;piezoelectric stack;flexure hinge;sophisticated driving;finite element analysis- 67
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Published：2020-08-12 -
Impact drive rotary precision actuator by piezoelectric bimorphs
Abstract：An impact drive rotary precision actuator with end-loaded piezoelectric cantilever bimorphs is proposed. According to finite element analysis and experiments of the dynamic characteristics of end-loaded piezoelectric cantilever bimorph, a certain method of fixed-frequency and adjustable-amplitude are confirmed to control the actuator. The results show that the actuator excited by fixed-frequency and adjustable-amplitude ramp voltage waveform work with large travel range(180°), high resolution(1 μrad) and speed(0.2 rad/min) and heavy-load ability(0.02 Nm). Having the advantages of high-precision positioning ability, simple structure and only one percent cost of traditional impact drive mechanism, it is expected that the proposed actuator will be widely applied to precision industry.Keywords：impact driving;piezoelectric bimorph;cantilever;finite elememt analysis- 38
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Published：2020-08-12 -
Piezoelectric-type stepping precision rotary actuator
Abstract：A new research scheme applying PZT stack into precision rotary actuator is proposed. Based on the analysis of the main mechanical structure and rotary working principle of the actuator, a mathematical model using PZT stack as actuator element is set up, and the mechanical structure is analyzed by finite element analysis software. Experiments of rotary resolution and moving stability on the prototype are conducted. The results show that the designed actuator has the advantage of high rotary resolution and large rotary angle,overcoming the coexisting problem between the moving resolution and large moving range of precision actuator.Keywords：rotary actuation;piezoelectric stack;finite element analysis;flexible hinge- 48
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Published：2020-08-12 -
Experimental research on double-chambered piezoelectric pump with membrane valves
Abstract：By experiment, many factors affecting the output ability of piezoelectric (PZT) pumps with double chambers are studied, which can't be explained with theories. A high efficient rubber membrane valve was made, and double-chambered PZT pump with high output capability was designed and fabricated. When powered by AC 120 V, series-wound PZT pump has a output of 520 ml/min, 22 kPa, and parallel-connectioned PZT pump has a output of 980 ml/min、28 kPa. The optimal chamber height is found , and PZT diaphragm actuating ways in series-wound and parallel-connectioned pumps are proved.Keywords：double chamber;membrane valve;piezoelectric pump;experimental test- 49
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Published：2020-08-12 -
Design of piezoelectric micro-pump
Abstract：This paper introduces a piezoelectric micro-pump with a new structure based on lamination, which adopts a cantilever check valve. In the laboratory the prototype pump has been designed and manufactured, the sine wave signal forming schematic circuit has been finished, which used to drive the micro pump after power amplification and voltage amplification. The systemic experiment research also has been done, the optimization project has been put forward, which adopts multi-chamber series connection structure to improve the performance of micro-pump. Through a series of experiments and tests, many beneficial conclusions have been drawn. the micro-pump possesses the stable work performance and owns higher ratio of performance to volume(the apparent dimension of pump: Ф15 mm×1.8 mm; the maximal low rate and backpressure of the micro-pump are about 3.6 ml/min and 22 kPa when applying 50 V sine wave driving voltage at 80 Hz). The structure and manufacture processing are useful for the design and development of the applied piezoelectric micro-pump.Keywords：cantilever check valve;micro-pump;piezoelectric pump;lamination- 26
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Published：2020-08-12 -
Performance of ultrasonic motor under vacuum and high temperature condition
Abstract：The performance of ultrasonic motor under abnormal conditions are researched, with five kinds of engineering plastics chosen as the rotor friction materials of traveling wave ultrasonic motor (TWUSM). By means of contrast test methods, effects of pre-load,degree of vacuum and surrounding temperature on friction driving properties of TWUSM are studied by using vacuum equipment and simulative TWUSM tester suitable. The results show that stalling torque increases and no load speed decreases with the increase of the pre-load and degree of vacuum. The no load speed decreases with the increase of surrounding temperature. Effects of degree of vacuum on contact states are analyzed by acoustics theory. The conclusion is that action of acoustic levitation makes dynamic contact force between stator and rotor reduce. The major reason the stalling torque in vacuum is higher than that in normal is that the effects of acoustic levitation decrease and the dynamic contact force increases.Keywords：Ultrasonic motor;Vacuum;temperature- 41
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Published：2020-08-12 -
Design and test of a micro -displacement actuator
Abstract：A set of micro-displacement actuator was developed and tested for the large area multi-object fiber spectroscopic telescope(LAMOST). Conventional techniques for micro-displacement mechanism with high accuracy and long travel in engineering applications are studied. In view of implementation principle of the active-motion mechanism in the LAMOST,integrated with precision lever,a scheme of stepper motor ,harmonic reducer and ball screw, the goal of both high accuracy and long travel is realized. The origins of error are investigated , before a computer look-up table is designed to calibrate transmission error and to improve absolute accuracy of the actuator. Measured with laser interferometer in laboratory,the actuator confirms itself that it can be used as micro-displacement actuator of the LAMOST, thanks to its resolution of 201 nm±48 nm and unidirectional accuracy of 237 nm(standard deviation) at a step of 10 μm.Keywords：mechanical micro-displacement actuator;error analysis;error correction;measurement;transmission mechanism- 57
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Published：2020-08-12 -
Theoretical study of all optical XOR using Mach-Zehnder interferometer
Abstract：Two kinds of Mach-Zehnder interferometers (MZI) were constructed by semiconductor optical amplifier (SOA) and linear optical amplifier (LOA), respectively. Based on rate equations, the pumping amplification and gain clamped behaviors of LOA are simulated. With the control of probe beam power and bias current, all-optical XOR functionality is simulated using integrated SOA-MZI and LOA-MZI numerical model at 40 Gbit/s. The performance of the XOR results is analyzed and compared by solving the rate equations numerically. The result differences of the XOR gates are explained from the structural properties. The theoretical results indicate that the high-speed operation is limited by the carrier recovery time in the SOA and LOA; the operation rate can be enhanced with appropriate bias current and probe beam power; LOA clamps the gain and improves tolerance against small signal distortion; the output signals of LOA-MZI have higher extinction ratio and lower power compared with SOA-MZI; LOA-MZI has better performance in output pulse shape than SOA-MZI.Keywords：Mach-Zehnder interferometer;all-optical logic XOR gate;semiconductor optical amplifier;linear optical amplifier- 50
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Published：2020-08-12 -
BP NN-based method for lens distortion correction of large-field imaging
Abstract：A method based on BP neural network(NN) is proposed in this paper,which realizes high precision of correction without knowing the mathematic model. 900 groups of light-point data are obtained as training samples by parallel light pipe method. A three-layer NN model with 6 nodes in the hidden layer is achieved and its correction effect is examined by 77 groups of data. The dual linear interpolation method is applied to the same 77 groups of data in comparison. The conclusion is that comparing to interpolation method, the BP NN method has higher precision and the BP NN method can avoid the problem of error estimation region in the interpolation method.Keywords：large angle of view;lens distortion;BP neural network;distortion correction- 59
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Published：2020-08-12 -
Automatic registration algorithm based on sensor parameters and target's contour centroid
Abstract：Based on the analysis of the imaging process of optoelectronic imaging anti-ship missile, an automatic registration algorithm is proposed, and its basic idea is to decompose the transform model and simplify it step by step. Originally, the distortion between infrared and visible images is affine. First, by adjusting sensor parameters, the scaling change between images is eliminated and the affine transform is simplified into rigid transform. Then depending on image information, the centroid of the target's contour is computed by morphological edge detection and chosen as control point, which is used to eliminate the translational change between images and achieve the complete alignment. Finally, the registration effect is assessed by judging whether the sea-sky-lines of the two registered images are superposed and using the rule of root mean square error. The simulation experiments convince that the algorithm is accurate, fast, and can meet the precision requirement for target recognition, providing a good way for solving the difficult registration problem of small target images with different sensors.Keywords：multi-sensor image;image registration;automatic registration;transform model;morphologic edge detection- 40
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Published：2020-08-12 -
Influence of chirp effects on FBG wavelength- matched demodulation precision and it's elimination
Abstract：The principle of wavelength-matched demodulation of fiber Bragg grating(FBG) is introduced. The correlation functions of reflective spectra of sensor fiber grating and wavelength-matched fiber grating are analyzed. The correlation functions are linearity to photoelectric detector output signals. The wavelength-matched demodulation based on maximum correlation, extremum judgment of photodetector output signal, are only available for alike reflective spectra. When the peak value judgment of photodetector output signal is adopted,chirp effects in the FBG sensor lead to demodulation error of Bragg wavelength. Theoretical analysis and experimental investigation show that the deconvolution of photodetector output signal can eliminate Bragg wavelength demodulation error influenced by chirp effects in the FBG sensor.Keywords：fiber Bragg grating;wavelength-matched demodulation;chirp effect;deconvolution- 68
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Published：2020-08-12 -
Application of raster metering to hull transverse twist measurement
Abstract：Some methods metering instrumentation ship's hull deformation are generalized, and their advantages and disadvantages are compared. A new raster metering method is put forward, which not only has some advantages of small bulk, light weight and ease of installation, but also has higher precision. A high precision sub-pixel location technology is used in this approach and the precision of angle metering can be higher. Through theoretic analysis and practical experiment, the results show the precision of angle metering has excelled 5 arc second.Keywords：image processing;sub-pixel processing;Deformation metering system;raster metering;Transverse twist angle- 34
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Published：2020-08-12 -
Relationship between parameters in hybrid optical/electronic joint transform correlator
Abstract：Based on the grid pixel structure of spatial light modulator(SLM) and CCD used in a hybrid optical/electronic joint transform correlator(JTC),the relationship among the structure parameters of SLM,CCD,Fourier transform lens and input images are presented. According to the relations,the JTC recognition processes are simulated with different distance between the object and the reference image which are equal in size:32×32 pixels.When the distance of the two input images is 64 pixels to 374 pixels,a perfect recognition result can be obtained. When the distance is less than 64 pixels,self-correlation peak and cross-correlation peak in the same order output signals can not be separated completely. The distance of more than 374 pixels results in the overlap of adjacent of correlation signals,and when the distance is more than 405 pixels,the JTC can not recognize the two input images.These simulation results have proved the theoretical analysis. The relationship is important to the configuration and application of JTC.Keywords：optical image correlation recognition;joint transform correlator;spatial light modulator- 33
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Published：2020-08-12
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