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Xiong X.,Guilin University of Electronic Technology | Xiong X.,Guangxi Colleges and Universities Key Laboratory of Optoelectronic Information Processing | Li S.,Guilin University of Electronic Technology | Li S.,Guangxi Colleges and Universities Key Laboratory of Optoelectronic Information Processing | And 6 more authors.
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2016

Pulsed laser radar detection performance is associated with laser optical pulse emitted by laser light source, and the performance of power supply directly determines the quality of optical pulse. According to the requirements of laser radar system, the high power MOSFET was used as switching device and the driving circuit model was established, designed and analyzed. The driving circuit with 10 ns minimum pulse width, 3.5 ns rising time and 50 kHz pulse repetition frequency was obtained successfully after much experiments. The optical peak power of LD nearly reached 60 W, and it was successfully applied in laser radar as laser emission part. The 3 cm/10.77 m accuracy can satisfy the requirement of a laser radar. © 2016, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved.

Wentao Z.,Guilin University of Electronic Technology | Wentao Z.,Guangxi Colleges and Universities Key Laboratory of Optoelectronic Information Processing | Junyang N.,Guilin University of Electronic Technology | Junyang N.,Guangxi Colleges and Universities Key Laboratory of Optoelectronic Information Processing | And 2 more authors.
Optical and Quantum Electronics | Year: 2015

Terahertz time-domain spectroscopy system was used to measure the characteristic absorption spectra of 8 transgenic cotton seeds in the frequency range from 0.3 to 1.5 THz. Comparing the similarities and differences of THz absorption spectrum of eight kinds of transgenic cotton seeds, which is based on spectral analysis, and using principal component analysis to perform qualitative analysis, the relevant data of spectral analysis was obtained. Three principal component factors were extracted in this paper, which the cumulative percentage variance reached 71.537 %. Therefore, different categories of transgenic cotton seeds were clearly distinguished according to the principal component analysis score chart. The experimental results indicated that nondestructive testing of transgenic cotton seeds could be achieved by using Terahertz time-domain spectroscopy system technology, which could be widely applied in the fields of agricultural seed selection, agricultural security and so on. © 2015 Springer Science+Business Media New York

Wang D.,China Jiliang University | Wang D.,China University of Technology | Chen X.,China Jiliang University | Xu Y.,China Jiliang University | And 6 more authors.
Precision Engineering | Year: 2015

Abstract The stage error of coordinate measuring machines (CMM) can significantly influence the measurement results, and it places ultra-high requirement on the measurement and calibration tools. A calibration technique based on self-calibration algorithm is presented to calibrate the two-dimensional stage error of CMM, and it can be carried out with a grid plate of the accuracy no higher than test stage. With the proposed self-calibration algorithm based on least squares method, the measurements at various position combinations of rotation and translation are carried out to separate the stage error from measurement results. Both the accuracy and feasibility of the proposed calibration method have been demonstrated by computer simulation and experiments, and the measurement accuracy RMS better than 1 μm is achieved. The proposed calibration method has a good anti-noise ability and provides a feasible way to lower the accuracy requirement on standard parts. It is of great practicality for high-accuracy calibration of the stage error of CMM and manufacturing machines in the order of submicron. © 2015 Elsevier Inc. All rights reserved.

Xu Y.,China Jiliang University | Wang D.,China Jiliang University | Wang Z.,China Jiliang University | Liu W.,China Jiliang University | And 4 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2016

In order to minimize the error, the non-lens imaging method is applied in the interferometric measurement of point-diffraction spherical wavefront precision. In the case of high numerical aperture and large lateral displacement, significant additional systematic error can be introduced into point-diffraction wavefront measurement result, and it cannot be removed with traditional calibration method. A high precision calibration method of structure error for point-diffraction wavefront interferometric measurement based on three-dimensional coordinate reconstruction and symmetric displacement compensation is proposed to calibrate the systematic error introduced by high numerical aperture and large lateral displacement in the measurement of point-diffraction spherical wavefront with non-lens imaging. Firstly, three-dimensional reconstruction method is used to pre-calibrate the symmetric error. Then, because the error introduced by point source lateral displacement in interferometric measurement is symmetric, the symmetric lateral displacement compensation is applied to further correct the residual structure error due to three-dimensional coordinate reconstruction error. Both the numerical simulation and experimental measurements are carried out to verify the feasibility of the proposed calibration method. According to the analyzing results, the calibration method can reach the correction precision better than λ/10000.The proposed calibration method is of great significance for the application of high precision calibration of structure error introduced by non-lens imaging interferometric measurement and high-accuracy measurement calibration of point-diffraction spherical wavefront. © 2016, Chinese Lasers Press. All right reserved.

Wu J.,Guilin University of Electronic Technology | Wu J.,Guangxi Colleges and Universities Key Laboratory of Optoelectronic Information Processing | Rao Y.,Guilin University of Electronic Technology | Hu Y.,Guilin University of Electronic Technology | And 3 more authors.
Yaogan Xuebao/Journal of Remote Sensing | Year: 2016

This paper presents our research on registering single aerial image to a LiDAR point cloud. Given its high spatial resolution, spatial positioning accuracy, and efficiency in capturing data of physical surfaces, LiDAR has been influenced by and has significantly changed photogrammetry. The fusion of LiDAR data with aerial images offers various applications, such as DOM generation, virtual reality, city modeling, and military training, because of the complementary nature of the information provided by the two systems. However, the two datasets should be geo-registered into a common coordinate frame prior to such integration, which proves to be quite challenging in terms of either automation or accuracy. Such a challenge may be partly caused by inefficiency in the feature measurement or detection stage. For example, the identification of point of interest or straight line feature is viable and reliable in optical images but is difficult to achieve in LiDAR point clouds because of its poor discontinuity measurements. To this end, an automatic geo-registration approach based on “pin-hole” imaging simulation and iterative gradient mutual information computation is proposed to align single aerial image to discrete LiDAR point clouds. The proposed approach takes photogrammetry collinear equation as strict mathematic mode and involves three stages. First, a virtual “pin-hole” imaging process restored from aerial image orientation parameters is established on urban LiDAR point clouds to generate simulated, gray, LiDAR-depth images. The generated LiDAR-depth images are geometrically similar to aerial images. Hence, difficulties in registration caused by distinct differences in spatial resolution, perspective distortion, and size between the two types of data sources can be greatly alleviated. Second, the geometric transform parameters between LiDAR depth images and aerial images are successfully estimated with the gradient mutual information as the similarity measurement. Moreover, the image pyramid partitioning strategy is implemented to accelerate the search for parameter space. In this stage, LiDAR laser feet points can be roughly mapped on aerial image pixels on the basis of the estimated geometric transform parameters and the known projection relations between LiDAR point clouds and their depth images. Third, the photogrammetry space resection algorithm is implemented using all the mapped aerial image pixels as observed values and their gradient mutual information as weight to improve image orientation parameters. The three stages are repeated until the given iterative calculation condition is met and the LiDAR point clouds are registered with single aerial image. Selected airborne LiDAR data and an aerial image with different initial parameter values are tested with the proposed approach. Approximately 0.5 pixel is obtained, indicating a higher registration precision compared with the ICP algorithm. (1) The “pin-hole” simulation imaging and iterative gradient mutual information calculation successfully resolve the difficult heterologous correspondence problem between LiDAR point clouds and optical aerial images; (2) The photogrammetry space resection algorithm can obtain registration parameters with minimum projection errors and reliable precision evaluation by maximizing the use of intensive space information from LiDAR data and recovering optical bundles of laser beams directly. © 2016, Science Press. All right reserved.

Nie J.-Y.,Guilin University of Electronic Technology | Nie J.-Y.,Guangxi Colleges and Universities Key Laboratory of Optoelectronic Information Processing | Zhang W.-T.,Guilin University of Electronic Technology | Zhang W.-T.,Guangxi Colleges and Universities Key Laboratory of Optoelectronic Information Processing | And 7 more authors.
Guangzi Xuebao/Acta Photonica Sinica | Year: 2016

An approach for recognition of transgenic soybeans was proposed based on spectral analysis in the terahertz (THz) range combing with Principle Component Analysis (PCA) and Back Propagation Neural (BPN) network. Eight principal component factors, whose accumulated variance reached 97.582%, were extracted from the original spectra data and then fed as inputs into the BPN network model. The utilization of the dimension-reduced data in training the network model can recognize the validation set accurately. The nondestructive testing of transgenic soybeans could be achieved by using THz spectroscopy, which could be widely applied in agricultural security areas. © 2016, Science Press. All right reserved.

Du L.,Guilin University of Electronic Technology | Du L.,Tianjin University | Li Q.,Tianjin University | Li S.,Tianjin University | And 8 more authors.
He Jishu/Nuclear Techniques | Year: 2015

Graphene, a two-dimensional layer of carbon atoms forming a honeycomb crystal lattice, has attracted much attention for its extraordinary carrier transport properties. The unique electronic structure of graphene gives rise to massless charge carriers and ballistic transport on a submicron scale at room temperature. The tunable electrical properties realized by raising or lowering the Fermi level, allow excellent tunability of electromagnetic structures made of this material. We used terahertz time-domain analysis of the composite structure. Here we demonstrate a significant amplitude modulation of THz waves with gated graphene by using extraordinary transmission through the graphene layer placed right above N-silicon substrate in the blue-violet laser of continuous irradiation. However, the reflection modulation of THz waves is weak monotonic. We employ the carrier transport properties of the graphene and the transport properties of the Schottky junction to analyze a graphene-silicon hybrid structure's strange transmission reasonably. © 2015, Science Press. All right reserved.

Chen X.,China Jiliang University | Wang D.,China Jiliang University | Xu Y.,China Jiliang University | Kong M.,China Jiliang University | And 4 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2015

Based on the fiber with sub-wavelength aperture, the point-diffraction wavefront with both high numerical aperture (NA) and high power is obtained, by which the poor light power of pinhole point diffraction wavefront and the small aperture angle of single-mode fiber point diffraction wavefront can be solved. We analyze the point-diffraction wavefront based on the finite difference time domain (FDTD) method, and the effects of various factors such as aperture, cone angle, film thickness of sub-wavelength-aperture fiber and NA on pointdiffraction wavefront error, aperture angle, light transmittance and intensity uniformity are discussed in detail. The simulation results show that an aperture angle about 90° and light transmittance about 29% can be obtained with 0.5 mm sub-wavelength fiber aperture, and the corresponding testing precision is better than root mean square value 0.0011λ within 0.60 NA. The simulation demonstrates the feasibility of high NA and high power of point-diffraction wavefront, and provides theoretical basis for choosing the dimension of sub-wavelength-aperture fiber in practical system design. ©, 2015, Chinese Optical Society. All right reserved.

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