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Issue 7 ， 2008
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Diffraction Characteristic of Varied line-space Grating
Abstract：Wavelength encoding long stroke fiber optic linear position sensor is a kind of optics displacement sensor, which used a Varied line-space grating (VLS grating) as the hardcore. The resolving power for the displacement depend on the resolving power for the spectrum, so the improvement of the resolving power for the spectrum is very important to the sensor. Based on the Fraunhofer diffraction, the diffraction patterns of VLS grating is obtained when the beam of incidence is parallel and uniform. The intensity of the diffraction facular changing with diffraction angle was figured out and pictured, when the diameter of incident facular was 5mm and 10mm to the same VLS grating, and when the diameter of incident facular was 10mm to different VLS grating.The result was validated by the experimentation for the sensor’s resolving power when the diameter of incident facular was different for the same VLS grating. The result revealed that the diameter of incident facular was very important to the sensor’s resolving power for the diffraction pattern of VLS grating.- 44
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Published：2020-08-12 -
Study on the detection of weak ultrasound signal using optical heterodyne interferometry
Abstract：A high-sensitivity optical heterodyne interferometer system was developed and used to detect weak ultrasonic signal. Polarized laser with good coherence was used as light source to improve interference intensity. A diaphragm was used to eliminate the optic noises and the influences of the feedback lights on the light path. Besides, the system is easy to be adjusted by using the 1 class light as reference. A square wave was used to excite the ultrasonic probe with 62.42 KHz central frequency and 74V amplitude; the measured vibration signal frequency and amplitude were 62.38 KHz and 76.4mV respectively using the proposed system. Experimental results showed that the optical heterodyne interferometer system can be used to detect the weak ultrasound signal.Keywords：laser ultrasonic;polarized light;Heterodyne interference;phase detection- 44
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Published：2020-08-12 -
QE 、LBIC AND I-V CHARACTERIZATION OF CAST-POLYCRYSTALLINE, EFG AND MONOCRYSTALLINE SILICON
Abstract：Three types of industrial silicon solar cells: P-type of cast-multicrystlline silicon, edge-defined film-fed growth (EFG) and single silicon solar cells have been analyzed, using spectral response (external quantum efficiency, EQE), light beam induced current (LBIC) and dark and illuminated current-voltage measurement (I-V). The diode equivalent model solar cells allows to deduce, from measured data, important cell parameters such as the ideality factors of diodes n, the saturation currents I0 and the parasitic resistance RS and RSH. The type of extended defect are discussed which effect these cells parameters in terms of the result of EQE and LBIC. For cast-multicrystlline silicon and EFG solar cells, the grain boundaries, dislocation and impurity in bulk silicon can be accounted for the degradation of cell parameter, but for single silicon solar cells maybe born-oxygen defect pairs.Keywords：silicon;solar cell efficiency;QE;LBIC;I-V;defect- 43
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Published：2020-08-12 -
A novel optimization method for Wavefront Coding
Abstract：Abstract：A novel optimization method for Wavefront Coding systems was designed, the method can be used to design Wavefront Coding systems just through commercial optical software, Code Ⅴ、Zemax etc. A triplet system was designed, and the Wavefront Coding technology added to the systems, which extend the depth of focus much than 10 times. At the end, a normal problem in the designning of Wavefront Coding systems, the trade-off between 'the insensitivity to defocus' and 'the restorablity' was discussed.- 49
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Published：2020-08-12 -
Study the Relationship between Fine Particle and Visibility
Abstract：Abstract: This paper discuss the effect of fine particle(PM2.5) on the visibility, and restablish the relationship between PM2.5 and visibility. In this paper the relative of PM2.5/PM10、size distribution and extinction coefficient is analyed by means of calculations based on the Mie scattering theory, The relativeship was validated by result of measured in Beijing. The study indicated that the pollution of PM2.5 is the main factor that results in visibility dropping, which is significative for clean out pollution of PM2.5 and improving atmospheric visibility.- 62
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Published：2020-08-12 -
Optimum Structural design of Gough-Stewart platform for fine poses adjustment of secondary mirror in large optical telescope
Abstract：Aiming at the structural design of Gough-Stewart platform for fine pose and position adjustment of secondary mirror in large optical telescope, analyzed the performance requirement for fine pose and position adjustment mechanism of secondary mirror in large optical telescope and brought out two design criteria for optimum structural design, one is Transmission Precision performance and the other is Stiffness performance. Selected two angular-dimensioned parameters and three nondimensionalized linear-dimensioned parameters as design parameters and explained the delimitation of define area of each design parameters. Brought out two Global Conditioning Indexes, one is Movement Precision performance index and the other is Stiffness performance index and adapted Reachable Workspace to the requirement of pose and position fine adjustment. In the guideline of unified objective method Multiply-Divide, constructed a unified objective function and built a mathematical model for constrained single objective optimization problem. Programmed in MATLAB base on an improved Genetic Algorithm and got the Pareto optimal solution, provided reference for further design.Keywords：Optimum structural design;Gough-Stewart platform;Fine pose and position adjustment;Secondary mirror;Optical telescope;Nondimensionalized parameters;genetic algorithm- 46
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Published：2020-08-12 -
Initial alignment of antenna for laser communication system between Aircraft and a ground station
Abstract：At first the composition of laser communication system is introduced in brief. Then composition and Algorithm Theory of Initial alignment of antenna for laser communication system between Aircraft and a ground station are elaborated in detail. By experiment the data of initial alignment of antenna is given, initial alignment of antenna is completed, the area of uncertainty is obtained. which is the foundation of antenna scanning.- 26
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Published：2020-08-12 -
A new method for measuring the refractive index of micro-quantity liquid
Abstract：Abstract：A new method for measuring the refractive index of micro-quantity liquid using glass capillary is introduced. the method based on imaging principle of a Coaxial Spherical Surface Optical System, the refractive index is obtained by measuring the focal position of a capillary filled with the liquid to be measured through a reading microscope, and then doing a calculation with an analytic formula deduced by us. Four liquid mediums, water, ethanol, ethylene glycol and glycerin have been measured, the required sample is less than 0.002 ml, the precise of obtained refractive index is better than 0.0003 for water and ethanol, and 0.0007 for ethylene glycol and glycerin. The method is characterized by using micro-quantity sample, simple equipment, easy to operate and high measurement accuracy, which is adapted to measure the refractive index of transparent or translucent micro-quantity liquid sample. Based on the deduced formula for calculating refractive index of liquid medium, we have analyzed the influence of the parameters (n0 ,R , r) of a capillary and the refractivity index to be measured (n) on the sensitivity of refractivity index (△d/△n) and the real image depth (Teff). The calculation results show that (1) either the decrease of r or the increase of R and n0 can enhance △d/△n effectively, however, Teff is also increased; (2) both Teff and d/n decrease with the refractivity index to be measured, and (3) the cross point of curves Teff (n) and △d/△n (n) determines the measurement range and precise of liquid refractivity index. The theoretically analyzed results provide an effective way to improve measurement precise and extend measurement range of liquid refractivity index.Keywords：refractive index of micro-quantity liquid;glass capillary;reading microscope- 55
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Published：2020-08-12 -
Extrapolation method to extend the dynamic range of the Shack-Hartmann wave-front sensor
Abstract：The maximum tolerable spot displacement of the Shack-Hartmann wave-front sensor is named dynamic range, and it is limited by the f-number of the micro-lens. It is well known that there is a trade-off between the sensitivity and the dynamic range, if the f-number is relatively short, a high dynamic range is achieved, but the corresponding sensitivity is degraded. Extrapolation method could overcome the trade-off; since the extrapolation method is a simple algorithm that does not change the measurement configuration, there is no requirement for extra hardware, multiple measurements, or complicated algorithms. In this paper, we not only present the theory but also actually implement measurement of a highly aerated wave-front.Keywords：adaptive optics;Dynamic range;Extrapolation method;Shack-Hartmann wave-front sensor- 78
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Published：2020-08-12 -
Study on the Fiber-Optic Fluorescence Measurement System for Pesticides in Soil
Abstract：the feasibility of measuring pesticides by fluorescence method has been analyzed on the foundational principle that molecules of organic substance can emit fluorescence when excitated by rays. A fiber-optic fluorescent measuring system, which can be used for detecting the organic pesticides in soil, has been put forward based on the techniques of fiber-optic sensing and fluorescence analysis. In the system, a pulsed xenon lamp is used as an excitation lamp source, a self-made cone-shape fiber-optic probe for detecting the fluorescence, a small-sized flat field grating spectrometer for dispersing fluorescence, a high-speed data-collecting module for collecting and converting the fluorescent signals. The fluorescence’s spectrum of the pesticide can be obtained with only one exposure of the system. In this way, the fluorescence experiments on carbaryl of different concentration in soil are done and the working curve and the minimum detecting limit of the system is examined. The results show the system can get high-resolution fluorescence spectra, and has a linear relationship between the fluorescence intensity and the concentration in the range of 0.005~0.1mg/kg. and the minimum detecting density(LOD) is 0.005mg/kg,the relative standard deviation(RSD) is ≤3 %. Consequently, the system can surely meet the need of detecting pesticides in soil.Keywords：Study Soil;Organic pesticide;optical fiber sensing;Fluorescence spectrum;Pesticide detecting- 33
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Published：2020-08-12 -
A novel process for fabrication of high mechanical reliability RF MEMS switch
Abstract：In order to increase the lifetime of the series contact MEMS switch with dielectric bridge, an isotropic undercutting process for forming the upper control electrodes and contact bar under the bridge is introduced. In comparison with the regular process, the introduced method can enhance the planeness of the bridge, avoid the problem of stress concentration, and thus improve the mechanical reliability of the switch. As a result, the yield rate of the switch increases from 10% up to 95%, and the lifetime is improved from 1,000 cycles up to 25,000,000 cycles. Under the actuation voltage of 23.3V, the insertion loss is 0.55dB＠DC-10GHz, and the isolation is 53.2dB＠DC-10GHz.Keywords：MEMS switch;contact;mechanical reliability;undercutting;lifetime- 38
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Published：2020-08-12 -
Speed test and control for ultrasonic motor working in vacuum
Abstract：Ultrasonic motor is a new-type, special motor, which can be applied widely in many fields such as aeronautic and astronautic field. Because ultrasonic motor is driven by friction，With the ultrasonic motor working for a long time its temperature rises continually , its resonance frequency drifts and speed will fluctuate. Especially in vacuum abstract air convection and heat conduction the ultrasonic motor’s temperature rises highly than in normal condition. This paper develops a system to test and control the speed of ultrasonic motor mainly made of SCM .Base the relation between the ultrasonic motor’s speed and its driving frequency, using Fuzzy PI control strategy control the speed of ultrasonic motor working in vacuum. Test proves that using the system the ultrasonic motor can work steadily in design speed in vacuum (the high vacuum degree up to 0.003pa), and the speed deviation don’t exceed 1 rpm.Keywords：ultrasonic motor;Vacuum;Fuzzy-PI control- 63
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Published：2020-08-12 -
Rough Set-based Fuzzy Control for On-line Monitoring Micro-size Drilling
Abstract：For online monitoring micro-size drilling, a rough set-based fuzzy control method was developed. The method gets rid of the disadvantages of over many fuzzy rule numbers and complicated calculations toward high-dimensional input fuzzy system. On the MATLAB platform, spindle motor’s 3-phase current signal data were on-line produced. Then connotative wear state information of micro-size drill was obtained and on-line monitoring to micro-size drilling process was performed. Results show that when monitoring threshold value is properly selected, the breakage of micro-size drill will be effectively avoided.- 48
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Published：2020-08-12 -
The research of multiple sensor fusion in large scale measurement
Abstract：The multiple measuring stations are always used to form measuring net in the geometric measurement of large scale workpieces. This method not only extends measuring bound, but also enhancing the redundancy. The spatial data registration of multiple measuring stations is based on singular value decompose, and then the data is fused by the optimum fusion criterion of matrix weighting linearity minimum variance. The validity of fusion criterion is proved by theory and simulation test, showing that the fusion precision is superior to each partial precision. The criterion has been applied to measuring net in tunnel component.Keywords：Large scale measurement;multiple sensor fusion;laser tracker;minimum variance- 28
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Published：2020-08-12 -
The application of laser scanning confocal microscope in micro-electro-mechanical system
Abstract：In micro-electro-mechanical system (MEMS), 3D micro structure analysis is becoming a powerful tool for charactering micromachining technique. With the deep research and the need for industrialization of MEMS, the importance of micro structure analysis in MEMS is increasing. Because of the advantages of high resolution, non-contact, and quick data-obtaining, etc., laser scanning confocal microscope (LSCM) is widely used in micro structure analysis. In the paper the imaging basis of LSCM is introduced, and the measurement of great angle and analysis of profile are especially introduced. Meaning while, the advantages and limits in micro structure analysis by LSCM comparing with stepper, SEM and white light interferometer are pointed out.Keywords：Laser scanning confocal microscope (LSCM);MEMS;Micro structure analysis;angle measurement;Profiler analysis- 44
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Published：2020-08-12 -
Transmission properties of adhesive single-layer bandpass FSS
Abstract：The compound structures of frequency-selective-surface(FSS) and dielectric slab were investigated by computation, based on modal matching method, and experimentation, taking slot arrays as illustrative examples. Frequency responses of FSS structures by different compounding approaches were analyzed, including the influence of polyimide base film and adhesive coating with different thickness. The results show that the influence of base film and adhesive coating in FSS structures can not be neglected, and they have a close relationship with the compounding approach and dielectric thickness. The compound structure should contain adhesive coating to eliminate the effect of air gap. If dielectric constants of base film and adhesive coating are less than or close to that of the slab, and if the slab is over 10 times thicker than base film and adhesive coating, the influence of base film and adhesive coating on the transmission properties of properly compound structures would be minimized. The comparison of measurement and computation of frequency response of FSS structures, loaded with dielectric slab of a series thickness on one side, shows that the flaw of adhesion would change the transmission properties of FSS structures. All factors above-mentioned should be considered in FSS design.Keywords：frequency selective surfaces(FSS);transmission properties;dielectric loading;experimentation- 38
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Published：2020-08-12 -
A Constant Temperature Thermal Vacuum Sensor Based on Micro-hotplate
Abstract：Micro-hotplate(MHP) is widely used in various of microsensors. Based on the thermal analysis of MHP, this paper analysed theoretically the effects of working temperature and dimensions on the working characteristics of micro-hotplate-based thermal vacuum sensor at constant temperature. A thermal vacuum sensor based on micro-hotplate was designed in which the supporting beams were 65μm long and 21μm wide, the gas gap below micro-hotplate was 0.5μm. The micro sensor was fabricated successfully with surface micromachining technology. The measured results shew that the fabricated vacuum sensor was sensitive in the pressure range of 2Pa～105Pa and the sensor response characteristics were in consistent with the calculated theoretical results.Keywords：Vacuum;micro-hotplate;thermal vacuum sensor;constant temperature- 47
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Published：2020-08-12 -
A novel pre-stressed six-component force sensor and its position and orientation error analysis
Abstract：In order to obtain the six-component force sensor with excellent comprehensive performance indices, this paper presents a novel pre-stressed six-component force sensor based on Stewart platform and performs its position and orientation error analysis. At first, compared with the traditional Stewart platform-based six-component force sensor, the structure feature of the pre-stressed six-component force sensor was described. Secondly, the mathematical model of the position and orientation error was built by using the influence coefficient method and vector method together. Then the position and orientation error sensitivity indices were defined and the influence conditions of different error factors on the sensor’s position and orientation error was analyzed by plotting histograms of error sensitivity. At last, the sensor prototype was developed and the calibration experimentation was carried out, and the experimentation results prove that the force measurement precision of the prototype is within 1%. The research contents of this paper are useful for the design and calibration experimentation of the six-component force sensor.Keywords：Force sensor;Stewart platform;pre-stressed;position and orientation error- 32
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Published：2020-08-12 -
Real-time adaptive inverse control based on neural networks for piezoceramic actuator with nonlinear and no-smooth hysteresis characteristic
Abstract：Objetive: In order to improve the actuator precision，a method for eliminating nonlinear no-smooth hysteresis characteristic of piezoceramic actuator is proposed. Method :An inner product-based dynamic neural network nonlinear and no-smooth hysteresis inverse model for piezoceramic is obtained, in which the feedback error learning method is used to avoid obtaining Jacobian information by model for piezoceramic. On dSPACE system platform，the piezoceramic is controlled by combined with a PID control and an neural networks adaptive inverse control. In order to satisfy the requirement of real time control, the programs is designed by a high efficiency and fast C-MEX S function. Result: Experimental results indicate that the precision of the proposed adaptive inverse control based on neural networks is 0.13μm, PID control precision is 0.32μm. Conclusion: The proposed control method removes efficiently the hysteresis characteristic of piezoceramic and of higher control precision.Keywords：piezoceramic;Hysteresis characteristic;Neural networks adaptive inverse control;dSPACE system;no-smooth- 48
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Published：2020-08-12 -
Optimized Design of PGF Compression Encoder Based on xDM Standard
Abstract：Solar Observations result in amount of data flow. In order to save storage space and network bandwidth, an xDM standard compatible PGF compression encoder is designed for the real-time image compression of solar image. First of all, the PGF compression algorithm which has great advantage over natural image compression and speed is analyzed and customized, and then a PGF compression encoder according to the interfaces required by xDM standard is designed. Against the features of the DaVinci hardware architecture, the PGF compression encoder is optimized on many implementations aspects such as software design, c language program and linear assembly language program. Finally, a real-time online testing has been carried out on the performance parameters such as ratio, time and SNR of the PGF compression encoder. Experiment result shows that the PGF compression encoder fully meets the design requirements of the real-time imaging processing system of solar telescope.Keywords：PGF;XDM;Encoder;DaVinci;image compression;optimization- 58
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Published：2020-08-12 -
A Motion Estimation Algorithm of Serial Star Images based on Self-adaptive Window Selection PIV technique
Abstract：For the star observation system, because of the movement of CCD flat, the CCD star serial images exist global movement. So, it is needed to estimate the motion parameter precisely. The invention and development of particle image velocimetry(PIV) indicate the important breakthrough of modern experimental fluid measurement. PIV is important both in the theoretical studies and application of the fields of fluid mechanics and aerodynamics. A motion estimation algorithm of serial Star images based on self-adaptive window selection PIV technique is proposed in this paper. The algorithm chooses analysis window of maximum energy by a self-adaptive method. Then the global motion parameter can be estimated through cross-correlation of the two analysis window. The experimental results demonstrate the algorithm is of high accuracy, and reduce the estimation error to be less than 0.01 pixel.Keywords：Particle Image Velocimetry(PIV);self-adaptive;star image;motion estimation;cross-correlation- 23
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Published：2020-08-12 -
Monte Carlo Simulation of multi-layered turbid media in Fourier-Domain OCT
Abstract：In order to look for track, which improve image quality of Fourier-Domain OCT (FDOCT), In this paper multi-layered turbid media is used. A FDOCT model is set up. Only single scattering is included and the illuminating light is infinite narrow beam. It is hard to obtain the exact solution of integrated scattering equation, for nth scattering brings to complex 3n integration. The simulation results indicate that two kinds of photons are different on spatial distribution. Multiple backscattering photons can be rejected by limiting the detection area and more single backscattering photons are received. Then discuss the differences between Time-Domain OCT (TDOCT) and FDOCT through theory and simulation, and further confirm the advantage of FDOCT. The simulation results are considered to be important guidance of experiments. The gray level of complexed bio-tissue image resulting from intensity reduction is approximately compensated through changing the model's structure.Keywords：Monte Carlo Simulation;Fourier-Domain OCT;First-order Born Approximation;multi-layered turbid media- 24
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Published：2020-08-12 -
An improved HSBH Algorithm against SPA
Abstract：SPA (Sample Pair Analysis) method is one of the most effective steganalysis for LSB steganography. It proves that SPA can detect HSBH algorithm in theory and experiment. Experimental results show that the correct rate of detection is nearly 100% when the embedding rate p>3%.And an improved HSBH Algorithm against SPA is presented. After improvement, no matter how much message is embedded, SPA steganalysis will get a very small estimate value and make an incorrect judgment, so attaining the hiding information securely. Finally the applicable range of SPA and the method which can resist SPA steganalysis are concluded.Keywords：steganography;LSB;HSBH Algorithm;SPA- 30
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Published：2020-08-12 -
An Anti-disturbing Method for Acquiring the Light-knife Center
Abstract：In the light-sectioning method, it is difficult to accurately extract light-knife center contour under those influences such as sun light, the surface texture information and low reflection of the measured objects. This paper presents an effective solution to eliminate those influences. Firstly, controlling the laser, two consecutive images in which only one image contains laser information are acquired. Then the background motion compensation is processed, making the two images have slightly difference only in the laser location, thereby the laser trace is emerged after using the technique of the image subtraction. Finally, through the data refinement and repair, a complete light-knife center contour is obtained. The results of experiments show that the method is effective in eliminating the influences mentioned above and adapt to measure 3D shape of the mobile objects in the measure locale.Keywords：light-sectioning;anti-disturbing;consecutive frames subtraction;background motion compensation;3D measure- 36
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Published：2020-08-12 -
RESEARCH OF MULTI-VIEW AND LARGE SCALE 3D DATA MOSIAIC BASED ON THE OPTIC CODED POINTS
Abstract：This paper presents a novel multi-view 3D coordinates data mosaic method, which utilize optic coded points in the two partial measurement overlap areas. The algorithm obtains the stereo vision sensor’s location and attitude transform matrix of the two partial measures(M and T matrix) by minimizing the linear least square criterion, then achieves the mosaic of measure results through transforming the latter measuring results into the coordinate system of the former measuring process. When adopt 12 coded points, the average error in 1.2m×1m×0.4m range (X, Y and Z axis) are 0.08mm, -0.07mm and -0.02mm. The result of the experiment shows that this method obtains superior mosaic precision, moreover, this method has no necessary to stick any target points on the object, which no-contact measurement could be fulfilled.Keywords：stereo vision;optic code;3D coordinates;mosaic- 47
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Published：2020-08-12 -
A Wavelet Embedded Block Coding Method Based on Block Bit-length
Abstract：A wavelet embedded block coding method based on block bit-length is brought forward in this article. The memory occupancy can be reduced through four measures which adopted in the arithmetic in the process of coding and coding efficiency can be increasingly improved, respectively. The four measures mentioned above are: (1)LLn sub-band separate coding; (2)establish block bit-length chart in terms of bit-length, the bit-length is defined by the author; (3)save the space of memory by employing bit-length chart instead of using lists in the process of delicating and ranking; (4)swift search key blocks according to the construction of bit-length chart to overcome repeat scan and increase the coding speed. According to the experimental results, the arithmetic can reduce memory occupancy in the process of coding and increase the coding speed effectively, meanwhile, it can keep the high quality of PSNR.Keywords：block bit-length;bit-length chart;embedded block coding;memory optimization- 37
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Published：2020-08-12 -
A compression algorithm of remote sensing image based on ROI for ocean surveillance satellite applications
Abstract：According to the characteristics of the remote sensing images from ocean surveillance satellite, an adaptive near-lossless compression algorithm based on ROI (Regions Of Interest) was proposed. After maximum lifting of morphological Harr wavelet, the objects were detected by threshold and connectivity analysis of eight adjacent regions in the lowest-resolution high-frequency sub-bands. ROI was depicted by intersection of enclosing rectangle and an annulus. In other resolution levels, the ROI of high-frequency sub-bands can be gained by mosaic magnification. In high-frequency sub-bands, Rice lossless entropy encoder was used for ROI, and bit plane encoder for background region, while DPCM and Rice for low-frequency sub-band. Experiments show that the algorithm could segmentalize the ROI effectively, gain better quality of reconstructed image compared with JPEG2000 and there is no visible segmentation trace. The algorithm possesses low complexity and is easy to be implemented in hardware. Moreover, it has the merits of adaptability, and independent data packet. So the algorithm can adapt to ocean surveillance satellite’s near-lossless compression applications.Keywords：ocean surveillance satellite;remote sensing image;morphological wavelet;region of interest- 53
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Published：2020-08-12 -
A camera rotator compensated algorithms based on sequence image frame matching
Abstract：In order to eliminate the measurement error caused by camera rotator during moving along the axial, a suit of high precision camera moving estimate algorithms based on character points image matching and least-squares estimate. Recur to the correlation of sequence image frame, and by analyzing the moving parameter of two continuous image frames, in the algorithms the character points on image are detected by Harris operator in the first; then match the character points based on image template in sequence frames; and moving parameters of the camera are obtained through least-squares algorithm last. By analyzing those parameters farther, the coordinate that laser spot relative to target center has been compensated, as a result, realization camera rotation compensated. Because the influence to image measurement precision by camera moving is overcome, the vice of low measurement precision on account of camera moving is remedied, and the measurement precision is heighten. The results of test and simulation show that the algorithms are effective and applied , but the real-time capability of the algorithms will still be improved.Keywords：measurement based on image;corner detect;image matching;moving estimate;least-squares- 28
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Published：2020-08-12 -
Imaging and Analyzing Subsurface Morphologies of Jade Objects with Optical Coherence Tomography
Abstract：Our work focuses on the new application OCT technology in gemstone testing. The main problem in jade research and industry is lack of portable fast measurement equipment for quality evaluation. Concerning the ability of exacting the two-dimensional subsurface structure, OCT imaging has the potential to obtain helpful microstructural characteristics and provide more scientific information for jade identification and research work. An optical coherence tomography (OCT) system applied in jade imaging and measurement has been implemented with scanning speed of 1 frame per second, depth resolution of 15um and penetration depth of 3mm. We demonstrate the experimental results and theoretical analysis of Jade imaging and measurement based on OCT method. From one hand, by processing the two-dimensional tomography data, we have provided two parameters to characterize the optical properties and then evaluate the transparency of jade qualitatively. From the other hand, according to the different optical backscattering properties, OCT imaging can be used to observe and provide some discrimination information on the impregnation and calcification of ancient jade materials. Experimental results show available microstructure information and confirm the feasibility of OCT method in evaluating transmission features and analyzing subsurface morphologies of archaic jades. Corresponding physical interpretation is also present in this paper.Keywords：optical coherence tomography;optical imaging and measurement;transparency;calcification;impregnation- 21
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Published：2020-08-12
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