光学仪器 光学分析仪器

TH744.4 2007054921磁动式氧含量分析仪的研制=A oxygen content magneto-motive analyzer[刊,中]/魏茂金(三明学院物理与机电工程系.福建,三明(365004)) ,赖森财…//光学精密工程.?2007 ,15(5) .? 761-766对磁动式测氧仪的测量池、光路和数据采集系统进行了研究。从气体磁性推导出了哑铃球在非均匀梯度磁场中受到的转动力矩公式,给出测量池系统的设计方案,采用镀银刻蚀方案实现哑铃球系统的转动阻尼,分析了非均匀梯度磁场系统的技术要求。介绍线阵CCD光点位置探测光路和CCD数据采集与处理电路系统。为满足仪器定标、温度补偿和校正的需…     

GJ-341光电经纬仪视差和反射镜角差的分析与控制

本文介绍了GJ-341小型遥控光电经纬仪双反射镜结构的特点,利用坐标转换的方法分析了GJ-341主摄影十字丝和双反射镜装配角差对设备测量的影响,讨论了该设备与一般经纬仪在外场标校和修正方法上的不同.提出了十字丝投影系统安装在双反射镜之前的建议.     

可在线校准的大气CO_2浓度光声光谱监测系统研究

Fs光声光谱系统的谐振频率和池常数通常在实验室由标准气体标定得到,但在实际应用中,由于标准气体本身的不确定度以及与被测气体成分的不同、环境温湿度的变化,使得现场测量中谐振频率和池常数与实验室标定结果有偏差,从而导致测量结果不准确。为了解决以上问题,提出了基于大气中氧气的在线校准技术,并将该技术用于检测大气中二氧化碳浓度的光声光谱系统。大气中氧气浓度恒定为20.964%,通过探测氧气在763.73nm附近的扫频信号及峰值信号,实现共振频率和池常数的在线校准。该系统中光声池为直径6mm,长度100mm的一阶纵向共振模式结构。理论上分析了环境温湿度、气体成分对光声池性能的影响,同时给出了用标准气体、室内空气和室外空气标定的谐振频率和池常数,在标定结果的基础上,测量得到室内和室外的二氧化碳浓度值。实验结果显示,与校准过的气体分析仪的测量值相比,用被测大气中的氧气标定的谐振频率和池常数计算的二氧化碳浓度更准确,相对误差小于1%,远小于实验室标准气体标定计算的浓度相对误差。创新处在于,直接利用大气中的氧气对光声池的池常数和共振频率进行在线校准,有效的减小了标准气体标定带来的误差,以及环境变化带来系统漂移,提高光声系统在线监测的准确性和可靠性。     

球共鸣声学法气体音速的测量原理及实验系统研究

本文阐述了通过音频信号共振频率测量气体音速的原理。同时还分析了实际的球共鸣器的结构对共振频率的影响并给予了相应的修正。据此设计和制作了一套高精度的球共鸣器和低频音频信号测量装置,建立了一套球共鸣声学法测量气体音速的实验系统。本文实验中研究温度、压力、气体音速测量的不准确度分别为±14mK、±2.0kPa和±0.0037％。通过对制冷剂R22饱和蒸气压和氩气低压下音速的测量验证了本实验系统的稳定性和精确性。     

���ײ��������ϵͳ�����ܲ���

对所研制的质谱测量与分析系统进行了性能测试。烘烤后系统的极限真空达到了7.3×10-7Pa,总漏气率为3.84×10-9Pa.m3.s-1。上下球室之间的气体压力,以及漏孔的漏气率与高分辨四极质谱计的氦分压力均呈现了良好的线性关系。结果满足动态流导法真空校准的技术要求,为氘、氦混合气体的测量与分析提供了条件。     

大孔径光学反射镜球铰支撑方式尺寸稳定性分析

采用球铰支撑可以极大地提高大孔径反射镜工作的可靠性,但必须对这种支撑方式进行合理的稳定性分析。球铰支撑方式的有限元分析必须围绕其支撑方式所具有的严格而又明显的接触特性、顶丝预紧力作用、具有相对滑动趋势而产生的摩擦这三大基本特征展开。应用传统的线性有限元分析手段对大孔径反射镜球铰方式支撑的尺寸稳定性分析具有较大的局限性。为提高分析精度,采用了非线性分析方法,最大程度地模拟实际结构,并将罚函数的摩擦形式引进到了摩擦接触对中,并对其进行了实际模型的解算,使得分析结果更加精确,并依据分析结果,对预紧力进行了合理地选取,使反射镜在一定的工作环境下能够稳定地工作,满足系统成像的需要。     

四反射镜光学系统像差分析与设计

反射系统具有体积小、重量轻成像性能优良等特点,在航天遥感中具有重要的应用潜力。分析了基于PW方法的四反射镜系统像差理论,推导了由系统遮拦比和放大率表示的系统初级像差表达式,并给出了四反射镜系统的基本设计过程。设计理论和方法适合于同轴四反射镜系统和离轴四反射镜系统的初始结构设计。基于PW方法的设计理论,设计了空间遥感用同轴四反射镜光学系统和一离轴四反射镜系统。两系统成像质量良好,结构紧凑,筒长与焦距之比可达1/6.4,体积和重量均满足技术指标要求,体现了四反射镜系统的优势,证明了理论分析的正确性与实用性。     

基于角反射镜的气体传感器

介绍了一种由两个角反射镜构成的气体传感器吸收池。利用角反射镜的反射特性和对光束的倾斜不敏感性,提高了吸收池的稳定性和灵敏度。用几何光学方法分析光束的传输特性。提出了探测光在单波长和双波长时的传输方程和系统的测量方程,构建了一种气体浓度检测系统。探测光在吸收池中来回传播的次数N由两个角反射镜的轴间距离决定,差分光吸收光谱(DOAS)的灵敏度与光在池内的传播次数N成正比。在N为3时,电池的检测阈值接近50 ppm     

基于角反射镜的气体传感器（英文）

介绍了一种由两个角反射镜构成的气体传感器吸收池。利用角反射镜的反射特性和对光束的倾斜不敏感性,提高了吸收池的稳定性和灵敏度。用几何光学方法分析光束的传输特性。提出了探测光在单波长和双波长时的传输方程和系统的测量方程,构建了一种气体浓度检测系统。探测光在吸收池中来回传播的次数N由两个角反射镜的轴间距离决定,差分光吸收光谱(DOAS)的灵敏度与光在池内的传播次数N成正比。在N为3时,电池的检测阈值接近50 ppm。     

非球面条纹扫描式剪切干涉检验法

本文论述用横向剪切干涉仪精确测量光学非球面波象差的方法。用计算机控制干涉相位测量技术,可进行高精度的检测和实时数据分析。本系统主要由有平行平板的横向剪切干涉仪、压电式驱动反射镜、象探测器和具有图象显示的微处理机组成。剪切干涉仪产生与波面导数相应的条纹图,用条纹扫描方法进行分析。对所得数据积分,便可求出波象差。对相对孔径为f/4的非球条面反射镜进行测量,测量精度为1/32λ均方根。     

Electrostatic micromirrors for subaperturing in an adaptive optics system

An electrostatic digital mirror device has been used to replace the lenslet array in a simple adaptive optics system. Clusters of binary pixels define the subapertures of the image plane and direct a small portion of the image onto a detector. The detector measures position shifts in the focused subaperture image caused by optical aberrations. Measurements on a digital mirror-based system and a similar lenslet-based system compare favorably to within a simple scaling factor. A subaperture system designed around a digital mirror device could aid in the development of a sequential subaperturing method that would replace the more complex schemes used in traditional adaptive optics.     

WIDE RANGE DETECTOR USING PARABOLIC CYLINDRICAL MIRROR FOR THz APPLICATIONS

A new, wide-band, high-speed and high-sensitivity THz detector has been developed. The prototype detector consists of a parabolic cylindrical mirror, a long wire antenna and a Schottky barrier diode. Direct detection measurements have shown a stable sensitivity of 150 ± 50 V/W for 1–2 THz without any adjustments. The long wire antenna was fixed at the focus of parabolic cylindrical mirror then it has been realized less operation steps, easy coupling to the external THz signals and a dramatic enhancement in the practicality of this system. The optically polished mirror and frosted surface one showed comparable sensitivities, thus easy polishing and less cost mirror fabrication can be applied for this system. The radiation pattern showed a maximum radiation angle of approximately 23° with its dominant main lobe, which was attributed to the wire antenna character and confirmed good agreements with classical antenna theory.     

Magnetic field effect on the binding energy of a hydrogenic impurity in coaxial GaAs/ AlxGa1−xAs quantum well wires

We propose a coaxial cylindrical quantum well wire (QWW) system, in which two conducting cylindrical layers are separated by an insulating layer. The ground state binding energy of a hydrogenic impurity subjected to uniform magnetic field applied parallel to the wire axis is studied within a variational scheme as a function of the inner barrier thickness for two different impurity positions and various barrier potentials. The ground state energy and wave function in the presence of a magnetic field is directly calculated using the fourth-order Runge–Kutta method. It is found that the binding energy in critical barrier thickness shows a sharp increase or decrease depending on the impurity position and magnetic field strength. The main result is that a sharp variation in the binding energy, which may be important in device applications, depends strongly not only on the location of the impurity but also on the magnetic field and the geometry of the wire.     

磁镜阵列像增强器的调制传递函数研究

基于三代近贴式像增强器,设计了磁镜阵列装置的结构,从理论上计算了该装置的调制传递函数以及将其引入像增强器后整体的调制传递函数,以此来分析对成像质量的影响.通过对实际参量绘制的调制传递函数曲线分析,得出磁镜阵列装置在X、Y方向的极限分辨率分别为117 lp/mm、121 lp/mm,奈奎斯特频率处的调制传递函数值分别为0.55、0.59,同时磁镜阵列像增强器的极限分辨率也分别达到了87 lp/mm、89 lp/mm,相应的奈奎斯特频率处的调制传递函数值为0.49和0.52.结果表明X和Y方向的调制传递函数曲线之间差异较之磁镜阵列装置变小,这对保证成像质量起到了积极的作用.文章为进一步深入研究磁镜阵列像增强器提供了重要的理论依据.     

Spin-controlled nanomechanics induced by single-electron tunneling

We consider dc-electronic transport through a nanowire suspended between normal- and spin-polarized metal leads in the presence of an external magnetic field. We show that magnetomotive coupling between the electrical current through the nanowire and vibrations of the wire may result in self-excitation of mechanical vibrations. The self-excitation mechanism is based on correlations between the occupancy of the quantized electronic energy levels inside the nanowire and the velocity of the nanowire. We derive conditions for the occurrence of the instability and find stable regimes of mechanical oscillations.     

脉冲线积分场测量系统的研制

介绍了脉冲线测量插入件磁场一二次积分的原理和测量装置的组成,分析了重力、噪声和反射波等因素对测量精度的影响,并采用对称安装金属线、夜间测量、油滴吸收反射波等方法减小了这些因素对测量的影响。脉冲线测量系统的测量结果与霍尔点测法相比符合得较好。利用该装置对实验室即将投入应用的电磁型圆极化波荡器进行了测量,验证了校正线圈和主线圈电流之间的关系。     

Improving the specularity of magnetic mirrors for atoms

An array of anti-parallel current-carrying wires creates an inhomogeneous magnetic field capable of reflecting neutral atoms. We present analytical and numerical analyses of the magnetic field produced by such an array, and describe methods for reducing the resulting rms angular deviation from specular reflection to less than 0.1 mrad. Careful choice of cross-sectional wire profiles is shown to dramatically improve specularity of reflection close to the surface. Additionally, we find that the specularity depends on whether the number of wires in the mirror is even or odd, and that there exists an optimal turning height above the surface that maximizes the specularity of reflection from the mirror. Received 16 November 1998     

Diamagnetic levitation of a milligram-scale silica using permanent magnets for the use in a macroscopic quantum measurement

Verification of macroscopic quantum mechanics requires that the position measurement accuracy of mirrors of various mass scales reach the Standard Quantum Limit (SQL) derived from Heisenberg's uncertainty principle. At mg-scale, thermal noise of the suspension wire of the mirror is an issue to reach the SQL. We propose to use a magnetic levitation system consisting of permanent magnets and yokes, noting the fact that a silica mirror is diamagnetic, and have succeeded in the experimental verification to levitate a 0.1-1 mg silica mass. This is the first demonstration of the levitation system with this mass scale and this magnetic susceptibility scale using permanent magnets as far as we know. We also estimated major noise sources for a 0.1 mg silica mirror and found the noise level to be lower than the SQL at 400 Hz-18 kHz. In conclusion, the levitation system of a mg-scale mirror for the use in a macroscopic quantum measurement was realized.     

Spin-dependent transport in a nanopillar non-local spin valve

We investigate the injection of a pure spin current into a non-magnetic Cu wire in a lateral spin valve. We detect the spin accumulation occurring at the interfaces between the magnetic nanopillars and the non-magnetic wire in the non-local geometry. We confirm that the accumulated spins diffuse equally in the Cu wire irrespective of the presence of a charge current. The inversion of the injector and detector magnetic nanopillars does not affect the spin signal, in agreement with analytical predictions for this system.     

Feedback Stabilization of a Corkscrew Istabilty

An application is made of lumped feedback to achieve stability of a distributed electromechanical system. A conducting elastic wire, placed in an axial magnetic field and carrying a current, exhibits instability at a certain threshold of magnetic pressure. The two dimensional transverse displacement of the wire is sampled and these signals are used to produce proportional feedback forces which allow stable equilibrium to be restored. A stability diagram is determined indicating the minimum feedback force to prevent static instability. For one station feedback, there is a maximum allowable feedback to prevent overstabil1 ity. In addition, the maximum value of destabilizing force which can be stabilized is somewhat less than that required for the second mode to become unstable. The wave dynamics of this corkscrew instability are related to several types of electromechanical interaction. The pinch confinement of a plasma, proposed as a scheme for containing a controlled thermonuclear reaction, suffers from a similar corkscrew instability.