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Study on Calibration Methods of Structured Light Sensor

中国光学学会2010年光学大会

作者： Zhijing Yu a,b,Xingliang Xu a,Shiliang Li a a Corresponding Author:Ground Support Equipment Research base of CAAC,Civil Aviation University of China,Tianjin 300300,China b state key laboratory of precision measuring technology and instruments,Tianjin University,Tianjin,China

The current traffic accident scene investigation method can not meet the demand of the social and transportation,considering the situation,a traffic accident swift reconnaissance system based on single mobile vision is proposed.。Imaged the coded targets distributed in the accident scene by the CCD camera in several locations and orientations,making use of the uniqueness and feature station’s geometric constraint of coded target,can realize automatic recognition and match of coded target and precise space scale constraint,then using fast bundle adjustment to calculate the initial external location and orientation of each camera and the 3D coordinate of space feature points,after that,running the process of Post-processing to correct or optimize the *** running the full-scale bundle adjustment algorithm to get the final 3D coordinate of the space feature points which is needed to been measured,it’s better to repeat the process of fast bundle adjustment and Post-processing several times,so the final three-dimensional information of the traffic accident scene will be calculated with high *** whole solving process is done automatically,so it is fast and *** experiment results demonstrate that the proposed method is feasible and flexible,and the error ratio is less then 0.06%.

关键词： traffic accident scene investigation computer vision coded target bundle adjustment

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Chinese Journal of Lasers 2002年第3期11卷 39-45页

作者： WANG baoguang HE Zhonghai LIAO Yibai CHEN Lincai (state key laboratory of precision measuring technology and instruments, Tianjin University, Tianjin 300072, China) Tianjin University State Key Laboratory of Precision Measuring Technology and Instruments 天津 300072

In this paper, advantages and disadvantages of existing calibration methods are presented. based on the projective transformation which is the basic principle of a CCD camera, a new method of calibrating structured li... 详细信息

关键词： structured light sensor projective transformation calibration

Research on Theoretical Model of Linear Frequency Modulation Interferometry

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Chinese Journal of Lasers 2000年第3期9卷 28-34页

作者： CHEN Yan ZHAO Yang (state key laboratory of precision Measurement technology and instruments, Department of precision instruments,Tsinghua University, beijing 100084,China) 清华大学精密测试技术及仪器国家重点实验室北京 100084

In this paper, the principle of linear frequency-modulation (LFM) with an external microcavity laser is analyzed mathematically and a method to establish the math model of LFM heterodyne interference is presented. The expression of LFM heterodyne interference is deduced by an illustration of a triangular frequency modulation. At present, one application of the LFM technique is non-guide absolute distance measurement. Experimental results of a system for absolute distance measurement based on a microchip solid laser and LFM technique are given. based on the precisely theoretical model some effective approaches to improve the performance of LFM and decrease the measuring error are discussed.

关键词： linear frequency modulation heterodyne interference absolute distance measurement

New Laser Interferometer with OPD Multiplication for Nanometer Measurement

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Chinese Journal of Lasers 1999年第5期8卷 3-5页

作者： ZHAO Meirong QU Xinghua WANG Hailong LU boyin(state key laboratory of precision measuring technology and instruments,Tianjin University, Tianjin 300072, China) 天津大学精密测试技术及仪器国家重点实验室天津

by using coupled differential interferometry a new laser displacement measurement interferometer with nanometric accuracy has been developed The resolution and the stability of the interferometer are improved by multiplicating the optical path difference (OPD). The new interferometer is simple in concept, symmetric in optical paths, without optical deadpath, easy to set up and align. λ/1600 resolution and nanometric accuracy are achieved within the measurement range of 10mm.

关键词： nanometer nanometroolgy laser interferometer displacement measurement differential interfrometry OPD multiplication

The Optical Characteristics of the Acousto-optic Tunable Filter with the Equivalent Point

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Chinese Journal of Lasers 2002年第2期11卷 55-60页

作者： XU Kexin NI Yong XUE bin JIANG Chengzhi HU Xiaotang( state key laboratory of precision measuring technology and instruments, Tianjin University, Tianjin 300072, China) Tianjin University State Key Laboratory of Precision Measuring Technology and Instruments 天津 300072

In this paper, the interaction curves of acoustic and optical waves in a non-collinear AOTF (acousto-optic tunable filter) cell under the parallel-tangent momentum matching condition are analyzed systematically. A new theory of equivalent point for AOTF design is put forward. The wavelength characteristics and the wavelength resolution of two diffraction beams with equivalent point design in AOTF are emphatically analyzed. The optical characteristics at δ = 0 (ideal case) and δ≠0 (real case) are also discussed. The advantages of the AOTF with equivalent point design include high wavelength resolution, more quantitative energy and larger incident angle aperture.

关键词： equivalent point momentum matching AOTF TeO2

Orthogonal linear polarized lasers (Ⅲ)——Applications in self-sensing

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Progress in Natural Science:Materials International 2005年第11期15卷 961-971页

作者： ZHANG Shulian, DU Wenhua and LIU Gang (The state key laboratory of precision Measurement technology and instruments, Department of precision instruments, Tsinghua University, beijing 100084, China) The state key laboratory of precision Measurement technology and instruments Department of Precision Instruments Tsinghua University Beijing 100084 China

In this paper, the applications of orthogonal linear polarized lasers in self-sensing are reviewed. The properties for such a laser include the production of a new frequency in one longitudinal mode spacing, the tuning of frequency difference, the change of polarization states as cavity tuning, the control of mode competition intensity, the optical feedback, and so on. The orthogonal polarized lasers have been used as a laser nanometer ruler based on competition between two polarized lights in a HeNe laser and as a displacement measurement tool based on the optical feedback in the orthogonal polarized lasers. They are also used in the phase retardation measurement of a waveplate, the angle measurement, the vibration measurement, the pressure/force measurement, the weak magnetic field measurement, and so on. The structures of these new devices are simple and compact with the great advantages of high resolution and high accuracy. Some of these devices can trace to the source of the laser wavelength. The nanometer laser ruler is an example whose measurement range is 12 mm, resolution is 79 nm and linearity is less than 5×10-5. The repeatability of the phase retardation measuring system of waveplate can reach 3’.

关键词： orthogonal polarized laser frequency splitting optical feedback vibration measurement displacement measurement waveplate measurement angle measurement.

Optic Fiber Interferometer for Absolute Distance Measurement

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Chinese Journal of Lasers 1997年第5期B6卷 435-440页

作者： WANG Zhong HONG Haitao XIAO Hai SUN Changku MENG Yan YE Shenghua (state key laboratory of precision measuring technology and instruments,Tianjin University, Tianjin 300072, China) Tianjin Univ Tianjin China

A synthesized scheme is presented to solve the ambiguity problems in ab-solute distance measurement, the principle and the structure of the system is introduced. The digital signal process for fast positioning is discussed in detail. Meanwhile, an expansion method is put forward to expand the dynamic range of the optic fiber interferometry system. Some experimental results are given.

关键词： absolute distance measurement optic fiber interferometer digital signal process

A New Technique for CCD Camera Auto-Calibration

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光学学报 2003年第S1期23卷 799-800页

作者： Xiaodong Zhang, Changku Sun, Zhixiong Wang, Wei Wei state key laboratory of precision measuring technology and instruments, Tianjin University, Tainjin, China state key laboratory of precision measuring technology and instruments Tianjin University Tainjin China

A novel feature-round-based coplanar drone for the CCD camera auto-calibration is designed. based on the ellipse similarity, an ellipse recognition algorithm is proposed. The experiment indicates the calibration error... 详细信息

关键词： Auto CCD A New Technique for CCD Camera Auto-Calibration for

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STUDY ON A PRECISE ON-SPOT CALIbRATION METHOD FOR DISTRIbUTED STEREO REFERENCE POSITION-SETTING

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Chinese Journal of Mechanical Engineering 2002年第4期15卷 324-327页

作者： Wang Zhong Kou Xinyu Chen Mingzhou Ye Shenghuastate key laboratory of precision measuring technology and instruments, Tianjin University,Tianjin 300072, ChinaXiong ChunbaoTianjin University Tianjin University State Key Laboratory of Precision Measuring Technology and Instruments 天津 300072

A high precision method used for on-spot calibration of distributed stereoreference position setting is presented. The high measuring accuracy in stereo reference calibrationis derived from using a high precision water level instrument and an accurate height verniercaliper. It settles the problem of reference calibration effectively and accurately, without usinglarge coordinate measuring machines (CMM). It is more adaptable and precise than traditionalcalibration methods applying theodolites or autocollimators. The error sources of this method areanalyzed in detail and several methods are developed to eliminate the calibration *** swallowtail-like anchor target is developed. Experiments show that the calibrationaccuracy can be limited within 0.06 mm in the range of 3～5 m and 0.03 mm with optimizing anchortarget. This method can be widely used in on-spot calibration.

关键词： position setting reference calibration water level on-spot inspection error analysis

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