测量单模光纤模场直径的一种新方法

本文根据单模光纤模场直径的横向位移定义,提出了一种测量模场直径的新方法——远场高斯掩模匹配法.讨论了几种测量及数据处理方法.最后给出了初步的实验结果.     

A STM point-probe method for measuring sheet resistance of ultrathin metallic films on semiconducting silicon

We report a novel approach for distinguishing surface, bulk and space–charge layer conductivities of metalized semiconductor surfaces. The method employs current injection from the tip of a scanning tunneling microscope and a spring-contact electrode placed on the surface in situ in UHV. The current–voltage behavior is sensitive to polarity in a way that distinguishes the surface contribution. The method is illustrated for the Si(1 1 1) 7 × 7 metallized surface and dependence of the conductivity with changing thickness of silver overlayers.     

A method for measuring the reaction rate of alkali metal with hydrogen gas

We present a simple, non-invasive optical technique that exploits collision-induced cross-fluorescence to monitor the amount of hydrogen in a sealed cell containing alkali metal, and reports its use in measuring the reaction rate of cesium with deuterium, both in the presence and absence of photo-excitation at 4555 Å.     

大口径锥体棱镜的制造与测量方法

锥体棱镜的设计要求一般为α≤5″,N=0.25,ΔN=0.2,是一种加工难度大,测量精度要求高的棱镜。采用对立方体加工形成锥体棱镜的制造方法,应用激光干涉测量技术对加工过程中的直角误差Δ90°、棱镜的出射光与入射光的偏离角误差α进行测量与控制,是一种既能满足设计指标要求又能满足大批量生产要求的加工方法。该加工方法适合于入射面圆直径在Φ50mm^Ф80mm的锥体棱镜。     

一种基于F-P标准具的金属线膨胀系数测量方法

本论文提出一种基于F-P标准具的金属线膨胀系数测量方法.该方法利用光杠杆将金属棒受热膨胀时的伸长量转化为F-P标准具干涉光场中干涉条纹半径的变化,通过测量干涉条纹的间距便可实现对金属线膨胀系数的测量.由于该方法仅需测量F-P标准具干涉光场中外侧条纹的间距,并且F-P标准具的多光束等倾干涉可以产生锐利的干涉条纹,因此测量过程更加简便,实验结果的精确度更高.通过实验测量验证了该方法的可行性与可靠性.     

Accurate method for measuring the thermal coefficient of group birefringence of polarization-maintaining fibers

We present a method to accurately measure the group birefringence variation with temperature in high-birefringence polarization-maintaining (PM) fibers using a distributed polarization analyzer. By analyzing polarization cross-talk peaks purposely induced at both ends of a PM fiber, the temperature coefficient of group birefringence can be accurately obtained. We confirm the theoretical prediction that the group birefringence of PANDA and TIGER PM fibers decrease linearly with temperature from -40 °C to 80 °C, and find that the temperature coefficients are -5.93 × 10(-7) °C(-1) and -5.29 × 10(-7) °C(-1) for two types of PANDA fibers, and -5.36 × 10(-7) °C(-1) for a TIGER fiber.     

A method for measuring the complex refractive index and thickness of a thin metal film

A circularly polarized heterodyne light beam is incident on a thin metal film, causing successive reflections and refractions to occur at the two sides of the thin film. The phase difference between p- and s-polarizations of the multiple-beam interference signal can be measured accurately with an analyzer and heterodyne interferometry. The phase difference depends on the azimuth angle of the analyzer, the complex refractive index and the thickness of the thin metal film. The measured values of the phase differences under three different azimuth angles of the analyzer can be substituted into the special equations derived from Fresnels equations and multiple-beam interference. Hence, the complex refractive index and the thickness of the thin metal film can be estimated by using a personal computer with a numerical analysis technique. Because of its common-path optical configuration and its heterodyne interferometric phase measurement, this method has many merits, such as high stability against surrounding vibrations, high resolution and easy operation. PACS 78.66.Bz; 78.20.Ci; 07.60.Cy     

利用电容器测量杨氏弹性模量

提出用可变电容器测金属杨氏弹性模量的新方法，并从实验上测定了碳钢丝的杨氏弹性模量。     

利用菲涅耳双镜测金属线膨胀系数

分析了菲涅耳双镜在干涉实验中 ,由金属受热膨胀引起的光源位置变化对干涉条纹的影响 ,导出金属受热时绝对伸长量与干涉条纹位置变化之间的关系 ,并通过它对黄铜棒的线膨胀系数进行测量。     

Interference method of measuring the extinction coefficient of birefringent optical fibers

The extinction coefficient of a birefringent optical fiber (the ratio between the radiation power output of the polarization mode and the radiation power transferred from this mode to another one) characterizes the capability of a birefringent fiber to retain the polarization state of the radiation. In relatively short birefringent fibers (1–100 m), the extinction coefficient may reach 10⁴–10⁶. Such high values of the extinction coefficient are difficult to measure by standard techniques (excitation of one polarization mode by an incoherent source with subsequent recording of the light intensity at the output of the analyzer). An interference method of measuring the extinction coefficient of birefringent fibers is suggested. It is based on using a coherent source and measuring interference oscillations caused by an additional phase modulation at the input of the fiber. This method does not require precise polarization matching between the laser source and fiber and considerably loosens requirements for the polarizer-analyzer extinction and resolution of the photodetector. As a result, using simple standard components (semiconductor laser, film polarizer, and photodetector), one can measure extinction coefficient as high as 10⁶. The suggested interference method of measuring the extinction coefficient of birefringent fibers receives a theoretical analysis, and experimental data obtained for 2- to 1000-m-long fibers are presented.     

轴径动态测量仪的研制

用单片机作为控制中心研制了轴径动态测量仪，该仪器能够实时显示被加工轴件的直径大小，提高了加工轴件的精确度，实现了在线测量．     

A novel method of measuring coherent ultrashort light pulses using diffraction by a grating

We propose a novel method of measuring coherent ultrashort light pulses in a single shot by monitoring the ratio of the energy of a pulse, diffracted by a grating, to the energy of the incident pulse. In the case of a gaussian pulse we present numerical calculations which allow easy determination of the pulse width. The proposed method is extremely versatile with respect to wavelength regions and pulse duration.     

A method for measuring the proportion of different plane orientations in metal supported catalysts by gas chemisorption

A method is presented, which allows us to calculate the percentage of metal surface atoms with different coordination numbers, on metal supported catalysts. This method is based on gas-metal stoichiometry values reported for the chemisorption of H₂, O₂ and CO on well defined monocrystals, and on gas chemisorption measurements on metal supported catalysts. It has here been applied to a series of Pd/SiO₂ catalysts.     

A simple method for surface and ultrathin film characterization

The method depends on monitoring variations of secondary electron emission as a function of changes in surface structure and composition. By measuring the crystal current i_cc and its variation with incident beam energy, E, surface changes can be measured rapidly and precisely. The principle of the method is already used qualitatively in secondary electron emission microscopy. If E is adjusted to give zero crystal current (E_zcc), and changes are followed from either variations in i_cc or E_zcc, then the measurements obtained during adorption are comparable to (but can be more precise than) those obtained from Auger spectroscopy. Results are presented for copper surfaces during cleaning cycles and during the adsorption of lead overlayers. Various applications can be envisaged, especially for rapid changes during segregation, diffusion or desorption.     

金属丝杨氏模量的光纤测试方法

采用光纤位移传感器,测量了加载情况下金属丝的微小伸长量,给出了一种杨氏模量的测量方法。理论上, 光纤位移传感器特性,与实验结果进行了对比。通过实验,标定了光纤位多传感器,并测量了不同加载情况下金属丝微小伸长量。采用逐差法处理了实验结果。     

A novel measurement method for the photosensitivity of fibers

An online measurement method for the photosensitivity of fibers is proposed. This method is simple and useful. Theoretical and experimental studies have been carried out. This method is based on the Mach-Zehnder interferometer (MZI). One arm of the MZI is externally exposed to UV light at 248 nm originating from a KrF excimer laser. Then the output optical spectrum is measured, by some relevant analysis, and the photosensitivity of the fiber can be obtained. The relationship between the refractive index increment of fibers and the exposure time is in accordance with the absorbing model that is brought forward by H. Patrick, which shows that this method has high precision.     

Optical fiber diameter measurement by the diffraction method with digital processing of the light scattering indicatrix

Relations between the position of the first diffraction minima and the fiber diameter are derived based on the solution of the problem of electromagnetic wave diffraction on a transparent fiber with a circular cross section. The obtained formulas are used to measure the fiber diameter. The diffraction pattern is recorded with a digital camera. The obtained image is digitally processed to determine the positions of the first two scattering indicatrix minima.     

单缝衍射测微小位移的实验室方法

介绍用单缝夫琅和费衍射测微小位移的原理和方法，并对测量误差等问题进行讨论。     

A method for reducing optical fiber diameter fluctuations

An optical fiber diameter monitor, Type GY-A, was developed especially for fiber drawing. A new method, the pulling force-temperature method, is presented. The fiber drawing stability is improved and the fluctuation of the fiber diameter is 0.3 μm (rms).