光电子立体摄影测量技术在体育动作分析中的应用

对基于视频的光电子立体摄影测量技术的基本原理与方法进行了介绍,还介绍了与此相关的系统误差和随机误差的误差源的一些研究成果,同时分析了这些误差在人体运动学参数之间的传播规律以及提高测量精确度和可靠性的方法。

大力发展光电子大地测量仪器适时形成数字化测绘技术体系产业

测绘是实现21世纪发展议程的基础性工具,也是保障全球持续发展战略中从事资源和管理的手段,测绘业的发展对国民经济的繁荣、资源的配置以及开展广泛的国际交流都具有十分重要的意义。测绘工作很重要的一方面是发展现代化的测绘技术体系,使之成为能够提供全面综合信息的新型产业。 随着科学技术的高速发展,特别是“三S”技术及高速数据通讯技术的快速发展。

Highly Sensitive Photodetectors Based on WS_(2) Quantum Dots/GaAs Heterostructures

The performance of the photodetector is significantly impacted by the inherent surface faults in GaAs nanowires(NWs).We combined three-dimensional(3D)gallium arsenide nanowires with zero-dimensional(0D)WS_(2) quantum dot(QDs)materials in a simple and convenient way to form a heterogeneous structure.Various performance enhancements have been realized through the formation of typeⅡenergy bands in heterostructures,opening up new research directions for the future development of photodetector devices.This work successfully fabricated a high-sensitivity photodetector based on WS_(2)QDs/GaAs NWs heterostructure.Under 660 nm laser excitation,the photodetector exhibits a responsivity of 368.07 A/W,a detectivity of 2.7×10^(12)Jones,an external quantum efficiency of 6.47×10^(2)%,a low-noise equivalent power of 2.27×10^(-17)W·Hz^(-1/2),a response time of 0.3 s,and a recovery time of 2.12 s.This study provides a new solution for the preparation of high-performance GaAs detectors and promotes the development of optoelectronic devices for GaAs NWs.

Si夹层对GaAs／AlAs异质结的影响

用MBE生长了GaAs/Si/AlAs异质结及其对比样,通过深能级瞬态谱技术(DLTS)和X射线光电子谱测量(XPS)研究了Si夹层的引入对异质结的影响,研究发现Si夹层的引入不会引起明显的深能级缺陷,异质结仍保持较好的质量,但使GaAs/AlAs的带阶发生了改变。

Measurement of Photoionization Cross Sections of the Excited States of Titanium

Resonance-enhanced multiphoton ionization of the titanium atoms has been investigated in the 293 321 nm wavelength. We couple a laser-ablated metal target into a molecular beam to produce free atoms. Ions produced from photoionization of the neutral atoms are monitored by a home-built time-of-flight mass spectrometer. Photoionization cross sections of the excited states of Ti I were deduced from the dependence of the ion signal intensity on the laser intensity for photon energies close to the ionization threshold. The values obtained range from 0.2 Mb to 6.0 Mb. No significant isotope-dependence was found from measurements of the photoionization cross sections of ^46Ti, ^47Ti, and ^48Ti.

Single Photon Detection of InGaAs/InP APD Based on Gated-mode Operation at Telecom Wavelengths

Based on the commercially available avalanche photodiodes, the basic needs of gated-mode operation for single photon are discussed. Gated-mode technique based on the experimental data for detection of single photon is analyzed at communication wavelengths so that the basic operation parameters can decide properly for efficient detection of single photon. The bias voltage has related to the punch-through voltage in combining the cooling technique with synchronization to decrease the dark counts.

北京光学仪器厂测绘仪器的发展及特点

本文重点论述我国数字化测绘体系产品的特点。根据这些特点,介绍我国大地测量仪器最重要的生产厂家—北京光学仪器厂(BOIF),近期开发的测绘仪器产品的品种系列、技术参数及特点。展示了我国大地测量仪器技术水平及产品结构、层次已进入一个新的发展阶段。

A robust method to measure residual stress in micro-structure

An experimental investigation on the residual stress in porous silicon micro-structure by means of micro-Raman spectros- copy is presented. It is shown by detecting the Raman peak shifts on the surfaces and cross-sections of electrochemical etched porous silicon samples with different porosities that serious residual stresses distribute complicatedly within the whole porous silicon structure. It is proved that micro-Raman spectroscopy is an effective method for residual stress testing on the micro-structures applied in optoelectronics and microelectronics.

Determination of Ultra Trace Level of Uranium in Electronic Materials by Fluorescence Spectrometry

Using ultra high purity NaF-NaKCO3 in the Fluorescence spectrometry, determination of sub ppb levels of Uranium in the electronic materials has been achieved. The method could be applied to determination of Uranium in any electronic materials.

Optically Powered Temperature Measuring Instrument for Big Rotor

Abstract: A micro - power consumption non - contact temperature measuring instrument for big rotor is introduced. As it solves very well the signal coupling under high speed rotation and power supply problem for probe, the instrument can realize persistent on - line temperature measurement for big rotor drived by the ordinary light transmitted by optical fiber under the room light.

Simulation and Error Analysis of Electro-optic Sampling Measurement of Ultrashort Electron Beam Bunch Length

For the development of high energy physics,it is needed to improve the performance of the relativistic electron bunch.The measurement of the ultrashort relativistic electron pulse becomes one of the key technologies.The electro-optic sampling measurement of relativistic electron pulses is a promising method.This method is nondestructive, non-intrusive,and real-time monitoring.Distance and angles of the reference frames will cause system deviations.In this paper these system deviations are analyzed by simulation.It provides a reference for the experiment.

Preparation of graphitic carbon nitride by electrodeposition

The CNx thin film was deposited on Si(100) substrate from a saturated acetone solution of cyanuric tri-chloride and melamine (cyanuric trichloride/melamine=1︰1.5) at room temperature. X-ray diffraction (XRD) results showed that the diffraction peaks in the pattern coincided well with those of graphite-like carbon nitride calculated in the literature. The lattice constants (a=4.79 ? c=6.90 ) for g-C3N4 matched with those of ab initio calculations (a=4.74 ? c=6.72 ? quite well. X-ray photoelectron spectroscopy (XPS) measurements indicated that the elements in the de-posited films were mostly of C and N (N/C=0.75), and N (400.00 eV) bonded with C (287.72 eV) in the form of six-member C3N3 ring. The peaks at 800 cm-1, 1310 cm-1 and 1610 cm-1 in the Fourier transform infrared (FTIR) spec-trum indicated that triazine ring existed in the product. These results demonstrated that crystalline g-C3N4 was ob-tained in the CNx film.

A single-photon fault-detection method for nanocircuits that use GaN material

As the complexity of nanocircuits continues to increase,developing tests for them becomes more difficult.Failure analysis and the localization of internal test points within nanocircuits are already more difficult than for conventional integrated circuits.In this paper,a new method of testing for faults in nanocircuits is presented that uses single-photon detection to locate failed components(or failed signal lines)by utilizing the infrared photon emission characteristics of circuits.The emitted photons,which can carry information about circuit structure,can aid the understanding of circuit properties and locating faults.In this paper,in order to enhance the strength of emitted photons from circuit components,test vectors are designed for circuits’components or signal lines.These test vectors can cause components to produce signal transitions or switching behaviors according to their positions,thereby increasing the strength of the emitted photons.A multiple-valued decision diagram(MDD),in the form of a directed acrylic graph,is used to produce the test vectors.After an MDD corresponding to a circuit is constructed,the test vectors are generated by searching for specific paths in the MDD of that circuit.Experimental results show that many types of faults such as stuck-at faults,bridging faults,crosstalk faults,and others,can be detected with this method.

A novel orientation measurement using optical sensor for spherical motor

The measurement of spherical rotor orientation is crucial to the close-loop control of spherical motors. This paper presents a novel method for the measuring of three-degree-of-freedom (DOF) rotor orientation of spherical motors using optical sensors. The spatial orientation of spherical rotor is output in the form of ZXZ Euler angles. Firstly, the structure of the measuring system composed of optical sensors and the patterns on the rotor surface are presented, and the operational principle of recognizing intersection points between the optical ring detectors and the latitude/longitude on the rotor surface is illustrated. The analytical model of input-output characteristic is established for the measuring system of three-DOF rotor orientation. Afterwards, the effect of parameters of the optical ring detectors on the linearity, sensitivity, resolving power and measuring range of the measuring system is analyzed using the analytical model. Finally, the feasibility of the measurement is validated through experiments of prototype measuring system. The analysis is expected to be a basis for the design parameter optimization of the orientation measuring system of a PM spherical motor.

Photo-Detached Electron Flux Distribution in a Gradient Electric Field

This paper investigates the flux distributions of the electron photo-detached from Hion localized in a gradient electric field. In contrast with the photodetachment in the uniform electric field [Phys, Rev. A 40 （1989） 4983], where only two electron trajectories interfere at each given point on a detector, for the photodetachment in a gradient electric field, the electrons waves can travel along multiple paths from the negative ion to a given point on the detector plane, which makes the electron flux distributions on the detector plane become much complex. Using the semi-classicaJ theory, we put forward a formula for calculating the electron flux. Our calculation results suggest that the electron flux distributions on a given detector plane is not only related to the propagation time of the detached electron, but also related to the detached electron＇s energy. With the increase of the detached electron＇s energy, the oscillating region in the electron flux distributions becomes enlarged and the oscillating structure in the flux distributions becomes much more complicated. This study will guide future experiment research on the photodetachment microscopy of the negative ions in the presence of non-uniform external fields.

Quantum well sub-bands probed by photo-excited, capacitance-sensitive resonant tunneling spectrum

By combining resonant tunneling spectra with capacitance-voltage (C-V) characteristics under photo-excitation, we have developed photo-excited, capacitance-sensitive resonant tunneling spectrum (PC-RTS) for probing the quantized levels of quantum wells in valence band. Inter-well tunneling events have been identified and are in good agreement with the calculated level scheme in the valence band of a quantum well-barrier-quantum well heterostructure. Compared to conventional resonant tunneling spectrum, our method shows remarkable advantages in higher sensitivity for discriminating electronic structures.

Electron transfer photochromism of Ln-based(Ln=Dy,Tb)coordinated behavior

Switching on/off single-molecule magnets(SMMs)at room temperature is still a challenge in moleculebased magnets.Herein,two photochromic Ln-based(Ln=Dy,Tb)phosphonate coordinated polymers were synthesized with regulable SMM behavior.The reversible room-temperature photo-coloration was an electron transfer process with a generation of relatively stable radicals,characterized by structural analyses,ultraviolet-visible,luminescence and electron spin resonance spectra and magnetic measurements.Importantly,owing to the antiferromagnetic coupling interactions between Ln^(3+) ions and photogenerated radicals,the room-temperature light irradiation surprisingly switched off the SMM behavior,showing the first example of radicalquenched SMMs in the molecule-based magnets.Moreover,the silient SMM behavior could be recovered after eliminating photogenerated radicals via heat treatment,showing a reversible off/on switch of SMMs via light and heat.This work constructs a system for switching off/on SMMs through electron transfer photochromism,providing a visual operation way via naked-eye-detectable coloration for the switchable SMMs.