基于光栅应变传感器的纳米测量机探针设计

为了提高纳米坐标测量机探针的测量精度,且能满足对复杂曲面或微结构进行精确测量的要求,提出了一种新颖的基于微探针系统的光纤布拉格光栅(FBG)探针。该探针具有较高灵敏度和可重复性。提出该新型FBG探针,即探针里有一个熔融的球形顶端,FBG作为应变传感器内置在测杆上。介绍了光纤探针的基本原理,并利用有限元软件ANSYS 11对探针的应变分布在轴向和横向载荷两种典型配置分别进行了仿真分析,结果表明仿真分析和理论计算相吻合。通过实验对光纤探针的灵敏度和分辨率分别进行测试。实验结果表明,在轴向载荷条件下,用位移分辨率为1.5 nm的压电换能器对探针进行性能测试,得到光纤探针的测量分辨率为60 nm。即光纤探针具有较高的灵敏度和分辨率,其性能满足实际测量需要。     

Electroless nickel plating on optical fiber probe

As a component of near-field scanning optical microscope （NSOM）, optical fiber probe is an important factor influncing the equipment resolution. Electroless nickel plating is introduced to metallize the optical fiber probe. The optical fibers are etched by 40% HF with Turner etching method. Through pretreatment, the optical fiber probe is coated with Ni-P film by electroless plating in a constant temperature water tank. Atomic absorption spectrometry （AAS）, scanning electron microscopy （SEM）, and energy dispersive X-ray spectrometry （EDXS） are carried out to characterize the deposition on fiber probe. We have reproducibly fabricated two kinds of fiber probes with a Ni-P film： aperture probe and apertureless probe. In addition, reductive particle transportation on the surface of fiber probe is proposed to explain the cause of these probes.     

Paired-angle-rotation scanning optical coherence tomography forward-imaging probe

We report a novel forward-imaging optical coherence tomography (OCT), needle-probe paired-angle-rotation scanning OCT (PARS-OCT) probe. The probe uses two rotating angled gradient-index lenses to scan the output OCT probe beam over a wide angular arc (approximately 19 degrees half-angle) of the region forward of the probe. Among other advantages, this probe design is readily amenable to miniaturization and is capable of a variety of scan modes, including volumetric scans. To demonstrate the advantages of the probe design, we have constructed a prototype probe with an outer diameter of 1.65 mm and employed it to acquire four OCT images, with a 45 degrees angle between adjacent images, of the gill structure of a Xenopus laevis tadpole. The system sensitivity was measured to be 93 dB by using the prototype probe with an illumination power of 450 microW on the sample. Moreover, the axial and the lateral resolutions of the probe are 9.3 and 10.3-12.5 microm, respectively.     

一种快速测量共聚焦X射线分析装置探测微元尺寸方法

共聚焦X射线荧光技术是一种无损的三维光谱分析技术,在材料,生物,矿物样品分析,考古,证物溯源等领域具有广泛应用。共聚焦X射线荧光谱仪的核心部件为两个多毛细管X光透镜。一个为多毛细管X光会聚透镜（PFXRL）,其存在一后焦点,作用是把X光管所发出的发散X射线会聚成几十微米大小的高增益焦斑。另一透镜为多毛细管X光平行束透镜（PPXRL）,其存在一几十微米大小前焦点,置于X射线能量探测器前端,其作用是接收特定区域的X射线荧光信号。在共聚焦Ｘ射线荧光谱仪中,PFXRL的后焦点与PPXRL的前焦点重合,所形成的区域称作探测微元。只有置于探测微元区域的样品能够被谱仪检测到,使样品与探测微元相对移动,逐点扫描,便能够对样品进行三维无损的X射线分析。探测微元的尺寸决定共聚焦X射线荧光谱仪的空间分辨率,因此精确测量谱仪的探测微元的尺寸是非常重要的。如图1所示,谱仪探测微元可以近似为椭球体,其尺寸可以用水平方向分辨率X, Y,和深度分辨率Z表示。目前,常采用金属细丝或金属薄膜通过刀口扫描的方法测量谱仪探测微元尺寸。为了精确的从三个维度测量探测微元尺寸,金属细丝直径要小于探测微元尺寸。金属细丝和探测微元都是数十微米级别的尺寸大小,很难把金属靠近探测微元。为了得到探测微元在不同X射线能量下尺寸变化曲线,要采用多种金属细丝测量。采用单个金属细丝依次测量比较耗费时间。采用金属薄膜可以很方便地测量探测微元的深度分辨率Z,但是当测量水平分辨率X, Y时,难以准确测量。为了解决以上谱仪探测微元测量中存在的问题,本文提出采用多种金属丝平行粘贴在硬纸片上作为样品用于快速测量探测微元尺寸。附有金属细丝的硬纸片靠近谱仪探测微元,可以将探测微元置于硬纸片所在平面。由于硬纸片与金属细丝在同一水平面,在谱仪摄像头的协助下,可以把金属细丝迅速的靠近探测微元。靠近探测微元后,在全自动三维样品台的协助下,金属细丝沿两个方向对探测微元分别进行一次二维扫描。通过对二维扫描数据的处理便可以获得探测微元尺寸随入射X射线能量变化曲线。采用此方法对实验室所搭建的共聚焦X射线荧光谱仪的探测微元进行了测量。     

Near-Infrared Spectroscopy Probe with Position Sensor

We propose a probe for near-infrared spectroscopy that enables exploratory diagnosis and the simultaneous measurement of metabolic status and dynaMisc of the body of a subject. The probe has a red light emitting diode for indicating its position in addition to a set of two near-infrared light emitting diodes and a photodetector for near-infrared spectroscopy measurement. The red light is detected by a camera and the probe position is obtained by processing the captured images. There are two methods of using the probe: In one method, the user scans the probe on the body surface to obtain a spatial distribution of metabolic status; in the other method, the probe is fixed on the body and simultaneously measures metabolic status and movement of the body to investigate their relationship.     

Electrostatic Probes for Studying Transport Properties in Tokamak Plasmas

Electrostatic probes for measuring the boundary plasma in tokamaks are reviewed and presented. Transport properties in JFT‐2, the ion temperature and the magnetic surface in JFT‐2M and floating potential fluctuations during the strong additional heating in JT‐60 are measured by several types of electrostatic probe the above‐mentioned purposes. The Langmuir probe including the double probe is applied to measure the spatial profile of boundary plasma in JFT‐2. The ion sensitive probe, the rotating cylindrical double probe, the asymmetric double probe and the differential double probe are applied to measure the ion temperature and magnetic surface in JFT‐2M. The reciprocating Langmuir probe applied to JFT‐2M observes the potential and density fluctuations and a new type probe is proposed for the quick diagnostic of core hot plasmas as a development of this probe. The fluctuation observed in JT‐60 is identified to be the ion cyclotron instability of the hot plasma caused by the strong anisotropy of the ion distribution function (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Physiological responses to the pulsation threshold paradigm. II: Representations of high-pass noise in average rate measures of auditory-nerve fiber discharge

In a companion article [L. I. Hellstrom, J. Acoust. Soc. Am. 85, 230-242 (1989)], it was shown that psychophysical pulsation threshold masking patterns (PTPs) for high-pass noise maskers are not a simple transformation of the profile of activity evoked in the auditory nerve by the masker. In this article, PTPs are compared with neural representations in which interactions of masker and probe are considered. It is hypothesized that, at pulsation threshold, some criterion value of rate change occurs when the stimulus switches from masker to probe. The iso-rate probe level, defined for single auditory-nerve fibers, is the probe level at which this rate change is zero. Iso-rate probe levels are lowest when probe frequency equals best frequency (BF) of the fiber. Profiles of iso-rate probe level versus BF (equal to probe frequency) are qualitatively similar to PTPs but differ quantitatively, e.g., in the rate of growth of probe level with masker level (1.2 dB/dB for PTPs, 0.54 dB/dB for iso-rate profiles). Quantitative differences can be further reduced by requiring a positive rate criterion. These results suggest that PTPs are not solely a reflection of the internal representation of the masker, but reflect responses to the probe tone as well.     

Particle‐in‐cell/Monte Carlo simulation of electron and ion currents to cylindrical Langmuir probe

Electron and ion currents to a cylindrical Langmuir (electrostatic) probe were calculated using the particle‐in‐cell/Monte Carlo (PIC/MC) self‐consistent simulation for a neutral gas in the pressure range 2–3,000 Pa. The simulation enables us to calculate the probe currents even at high neutral gas pressures when the collisions of collected charged particles with neutral gas particles near the probe are important. The main aim of this paper is the calculation of probe currents at such high gas pressures and the comparison of the results with experimentally measured probe currents. Simulations were performed for two cases: (a) probes with varying radii in a non‐thermal plasma with high electron temperature at low neutral gas pressure of 2 Pa (in order to verify the correctness of our simulations), and (b) probe with the radius of 10 μm in the afterglow plasma with low electron temperature and a higher neutral gas pressure (up to 3,000 Pa). The electron probe currents obtained in case (a) show good agreement with those predicted by the orbital motion limited current (OMLC) theory for probes with radii up to 100 μm for the given plasma conditions. At larger probe radii and/or at higher probe voltages, the OMLC theory incorrectly predicts too high an electron probe current for the plasma parameters studied. Additionally, a formula describing the spatial dependence of the electron density in the presheath in the collisionless case is derived. The simulation at higher neutral gas pressures, i.e. case (b), shows a decrease of the electron probe current with increasing gas pressure and the creation of a large presheath around the probe. The simulated electron probe currents are compared with those of measurements by other authors, and the differences are discussed.     

Effects of stimulus level on forward-masked psychophysical tuning curves in quiet and in noise

Forward-masked psychophysical tuning curves were obtained from normal-hearing listeners at different probe levels in quiet and in a broadband background noise. In quiet, tuning-curve shape changed with probe level. For six listeners, tuning curves became broader with increasing probe level, primarily due to a decrease in the low-frequency slopes. For one listener, tuning curves became narrower with increasing probe level. The addition of a background noise, which was presented continuously at a level 10 dB below the noise level required to mask the probe tone, reduced the masker levels required to mask the probe tone. The reduction was greater near the tip of the tuning curve than on the tail, so that tuning curves in background noise were narrower than those obtained in quiet. Tuning curves with comparable masker levels near the tip of the tuning curve (Lmtip) were similar in shape, regardless of probe level or whether tuning curves were obtained in quiet or noise. Comparisons of tuning-curve characteristics derived by fitting tuning curves with least-squares procedures, indicated that low-frequency slopes decreased with Lmtip. As a consequence, Q10 dB values decreased with Lmtip. These results are consistent with the interpretation that tuning-curve shapes are determined by the intensities of the maskers required to mask the probe tone. The addition of a background noise restricted (partially masked) the excitation pattern of the probe so that lower masker intensities were required to "forward mask" the probe tone, and narrower tuning curves resulted from less intense markers. The results are well described by a two-process model of auditory excitation patterns.     

Characterization of cross-polarization modulation on a two channel WDM system

This article contributes experimental corroboration of cross-polarization modulation (XPolM). A continuous wave probe signal is remotely controlled by a modulated pump signal. Experimental results show that the state of polarization (SOP) evolution of the probe signal resembles that of the pump signal to a confined region on the Poincaré sphere. Further a bit pattern is transmitted on the probe signal by making use of cross-phase modulation induced nonlinear polarization rotation of the probe signal. The article also gives evidence to the detrimental effect cross phase modulation may have on polarization mode dispersion compensators. The results show that the degree of polarization degradation of a probe signal in a two model wavelength division multiplexing system deteriorates with an increase in the power ratio between the pump and probe signal.     

Probe‐assisted spin manipulation in one‐dimensional quantum dots

We study a spin structure that arises in a one‐dimensional quantum dot with zero total spin under the action of a charged tip of a scanning probe microscope in the presence of a weak magnetic field. The evolution of spin structure with changing the probe position is traced to show that the movable probe can be an effective tool to manipulate the spin. The spin structures are formed when the probe is located in certain regions along the dot due to Coulomb interaction of electrons as they are redistributed between the two sections in which the quantum dot is divided by the potential barrier created by the probe. There are two main states: spin‐polarized and non‐polarized ones. The transition between them is accompanied by a spin precession governed by the Rashba spin–orbit interaction induced by the electric field of the probe. In the transition region the spin density changes strongly while charge distribution remains nearly unchanged. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

A Comparative Study of Single and Double Langmuir Probe Techniques for RF Plasma Characterization

In this study, the plasma density and electron temperature of Radio Frequency (RF) plasmas were determined by three types of Langmuir probes, namely a conventional double probe, a single probe with RF choke and a single probe with RF choke and compensating electrode. The same plasmas were characterized by the three probes, each performing three measurements per plasma condition, in order to determine the precision of the measurement results. After performing a comparative analysis, which looked at the precision and the accuracy of these results, the conclusion is that the double probe, which has already the advantage of the simplest construction, yields the most reliable results for both capacitively and inductively coupled RF plasmas. The single probe with RF choke and compensating electrode has a similar precision as the single probe without compensating electrode, but its accuracy is better.     

四能级Tripod-型原子系统中量子相干导致的交叉Kerr非线性效应

计算了四能级Tripod-型原子系统中探针光极化率随其频率失谐量的变化曲线.结果表明,当触发光作用于该系统的一个共振跃迁能级时,可使探针光的吸收和色散在其电磁感应透明(Electromagnetically Induced Transparency,EIT)窗口(由耦合光产生)处发生显著变化.随着触发光Rabi频率的增加,探针光在EIT窗口的吸收显著降低,色散显著增加.这种由触发光引起的探针光极化率的变化对应着三阶Kerr非线性光学效应,这一效应在偏振量子相位门中有着潜在的应用价值.     

纳米表面相互作用及振动测头模型

如何实现高精度的测量是现代制造业及微电子技术领域的热点问题之一. 基于微纳米测头的三坐标测量机是当前实现高精度测量的重要手段. 随着测量尺寸的减小, 常用的纳米/微纳尺度的测头与待测表面之间形成静态接触, 其表面相互作用成为了影响其测量精度和可靠性的关键因素之一. 本文基于一种触发式振动测头, 研究了其动力学模型, 并通过对测头纳米尺度表面相互作用的理论分析及数值模拟, 确立了测头振动参数与表面相互作用之间的关联. 实验研究表明, 参数优化后的谐振微纳测头能有效抑制表面作用带来的干扰, 提高测量精度.     

Development of Raman-shifted probe laser beam for plasma diagnosis using polaro-interferometer

Optical diagnostics of laser-produced plasma requires a coherent, polarized probe beam synchronized with the pump beam. The probe beam should have energy above the background emission of plasma. Though the second harmonic probe beam satisfies most of the requirements, the plasma emission is larger at the harmonic frequencies of the pump. Hence, at high intensities we need a probe beam at non-harmonic frequencies. We have set up a Raman frequency shifted probe beam using a pressurized hydrogen cell that is pumped by the second harmonic of the Nd glass laser that operates at only one Stokes line of 673.75 nm.     

Modulation interference in detection and discrimination of amplitude modulation

Two experiments were conducted to assess the effect of the rate of sinusoidal amplitude modulation (SAM) of a masker tone on detection of SAM of a probe tone (experiment 1) or on SAM-rate discrimination for the probe tone (experiment 2). When modulated at the same rate as the probe, the masker interfered with both the detection of probe modulation and the discrimination of the rate of probe modulation. The interference was obtained when the masker was either higher or lower in frequency than the probe (the probe and masker were separated by 2 oct). The amount of interference in detecting probe modulation (experiment 1) decreased as the common base rate of modulation was increased from 5 to 200 Hz. For rate discrimination (experiment 2), the amount of interference remained approximately the same for base rates of 2-40 Hz, the range over which rate discrimination was measured. In both experiments, the amount of interference was reduced when the masker was modulated at a different rate than the probe.     

Coherent Control of the Hartman Effect through a Photonic Crystal with Four-Level Defect Layer

In this paper, we examine the transmission of a probe field through a one dimensional photonic crystal (1DPC) when the sixth layer of the crystal is doped with four level atoms. We analyze effects of the external driving field on the passage of weak probe field across the photonic crystal. It is found that for the phase time delay of the probe photons, intensity of the driving field switches the Hartman effect from sub to superluminal character. It is interesting to note that in our model, the superluminal transmission of the probe pulse is accompanied by a negligibly small absorption of the incident beam. It ensures that the probe field does not attenuate while passing through the photonic crystal. A similar switching of the Hartman effect may be obtained by adjusting detuning of the probe field related to the excited states of the four-level doping atoms.     

Spectral modulation and supercontinuum generation assisted by infrared femtosecond plasma grating

Spectral modulation and supercontinuum generation of a probe pulse is investigated by using the plasma grating induced by the interference of two infrared femtosecond laser pulses. The dependences of the supercontinuum generation from the probe pulse on the time delay, the relative polarization angle between the probe pulse and the two-pump pulses, and the input probe pulse energy are investigated. The far-field spatial profiles of the three pulses are measured with different time delays and relative polarization angle, and the core energy of the probe pulse as functions of the time delay and relative polarization angle are also shown.     

Solvation and Solvent Relaxation in Swellable Copolymers as Studied by Time-Resolved Fluorescence Spectroscopy

The fluorescent probe dimethylaminonaphthylsulfonamide is covalently bound to the ends of the pol(ethylene glycol) chains of the swellable block copolymers poly(ethylene glycol)–polystyrene (PEG-PS) and poly(ethylene glycol)–poly(ethylene imine) (PEG-PEI) to investigate the molecular mobility inside the polymers, swollen by different liquids. Steady-state and time-resolved studies of the Stokes shift between absorption and fluorescence spectra reveal that the probe is solvated by both the polymer matrix and the liquid phase. The extent of solvation by the liquid and the mobility of the microenvironment of the probe depend on both the swelling volume of the polymer and the solubility of the probe in this liquid. Steady-state and time-resolved fluorescence depolarisation measurements show that the polymer matrix forms a very rigid solvent cage, which almost completely immobilizes the probe. Upon solvation of the probe by the liquid, the mobility of the probe increases. In PEG-PEI swollen by polar solvents, the mobilities of the probe itself and of its microenvironment, although not reaching the values observed in homogeneous solution, are significantly higher than in PEG-PS, due to the hydrophilic nature of the polymeric backbone in PEG-PEI.     

An electrostatic model of the cutoff probe

Although a circuit model of the previously developed cutoff probe for plasma diagnostics elucidates the basic physics and contributes to the development of the cutoff probe, a theoretical validation of the circuit model has yet to be accomplished. For theoretical validation, this paper proposes a one-dimensional electrostatic model, or 1dESM, of the cutoff probe, which is based on electrostatic field analysis in a finite two-wire approximation. The transmission spectrum S₂₁ calculated by the 1dESM shows a good agreement with that from a three-dimensional full electromagnetic wave simulation for various electron densities and pressures. Based on the 1dESM, the formation mechanism of the S₂₁ of the cutoff probe was analyzed. Theoretical validation of the circuit model was then achieved by comparing the circuit model with the 1dESM. This paper is believed to contribute to a better understanding of the cutoff probe and to the development of cutoff probe models.