Evaluation of holographic emulsion movement using phase difference amplification

A real-time holographic interferometry technique is typically used in the evaluation of aberrations caused by movement of the photographic emulsion. However, this technique is insufficiently accurate when an emulsion, with strain which has been released prior to exposure, is used. A proposed solution is based on the difference amplification method, which uses the higher diffraction orders of a non-linearly recorded hologram.     

A new method for generating and analysing digital speckle shearing correlation fringe patterns

A method for generating a high visibility digital speckle shearing fringe pattern is proposed. A three-step phase shifting technique which involves the introduction of arbitrary phases is utilized. The phase shifting technique is carried out using a rotating mirror and a theoretical model which involves a linear correlation algorithm is discussed. Experimental results showing correlation fringe patterns and a deformation phase map are presented.     

Research note: Vibration amplitude measurement using a fringe-counting technique

A simple, self-calibrating vibration amplitude measurement technique, which employs a Twyman-Green interferometer and a fringe-counting technique, is proposed. It has been experimentally shown to be accurate to within the quantization error of an optical half wavelength.     

Approximate Analytical Solutions for a Class of Laminar Boundary-Layer Equations

A simple and efficient approximate analytical technique is presented to obtain solutions to a class of two-point boundary value similarity problems in fluid mechanics. This technique is based on the decomposition method which yields a genera/analytic solution in the form of a convergent infinite series with easily computable terms. Comparative study is carried out to show the accuracy and effectiveness of the technique.     

Nondestructive testing by ESPI and quasi phase shift gradient technique

A new nondestructive testing (NDT) technique, which is based on Electronic Speckle Pattern Interferometry (ESPI) and digital image processing with quasi phase shift and gradient technique, is presented. A simple phase reduction algorithm is developed, which replaced an accurate phase shifter. Compared with other phase shift techniques, this method is insensitive to environmental vibration and air disturbance, has visible procedures and results allows the object to move slowly during the inspection procedure, does not need phase unwrapping, and has a quick image processing speed. As an application, this NDT technique is used to detect defects in composite materials and the resulting deformation phase gradient image shows a better visual effect than normal ESPI.     

Color signal correlation detection by matched spatial filtering

A polychromatic correlation detection technique by complex spatial filtering is presented. This technique utilizes a diffraction grating and three co-lineared (red, green, and blue) coherent sources. The technique of complex spatial filter synthesis for the polychromatic corelation detection is demonstrated. This technique offers true color correlation detection which is very suitable for color signal recognition and identification. The correlation diffraction efficiency with this technique is generally higher than that of the wavelength-multiplexed technique. Several interesting experimental demonstrations of this color signal correlation detection scheme are provided. Finally we note that this color signal detection technique is a simple and versatile processing technique which has broad range of applications of complex color signal detection, recognition and identification.     

Microstructural characterization using diffuse backscatter: theory and experiment

A microstructure characterization technique is presented which utilizes the azimuthal moments of backscattered intensity to determine the Legendre moments of the microstructure's phase function. The technique is based on a late-time, diffuse approximate solution to the radiative transfer equation. Monte Carlo simulations are presented indicating that the technique is robust for the first azimuthal moment but less so for higher-order moments.     

Molecular contrast in optical coherence tomography by use of a pump-probe technique

We describe a novel technique for contrast enhancement in optical coherence tomography (OCT) that makes possible molecular-specific imaging for what is believed to be the first time. A pump-probe technique is employed in which a pulsed pump laser is tuned to ground-state absorption in a molecule of interest. The location of the target molecule population is derived from the resulting transient absorption of OCT sample-arm light acting as probe light. A signal processing technique for three-dimensional localization of the transient absorption signal is described, and preliminary results exhibiting OCT contrast from methylene blue dye in multilayer and scattering phantoms are presented.     

断续流动氢化物发生法在AAS／AFS中的应用

本文介绍了一种介于流动注射法及连续流动法之间的氢化物发生进样技术。这种技术被称为断续流动法。它具有装置简单，灵活性大，运转成本低等特点。目前，已成功地应用于氢化物原子吸收法及氢化物原子荧光法中。     

投影栅相位法三维曲面的光学检测技术

利用投影到三维曲面的畸变光栅，采用二维数字图像处理，建立了一种新型的快速、高精度三维曲面无接触光学检测技术，开妈了基于微机上的全套应用软件，并以一个典型的汽车覆盖件为例进行了实验分析。文中还提出一种边界处理技术，用以提高系统的处理精度。     

基于超声波测量技术的颗粒尺寸分布模型的研究

提出了一种利用单颗粒背向散射信号来进行粒径分布估算的超声波测量技术,系统阐述了其 理论基础及基本工作原理。被测颗粒的散射信号幅度与它在探测区中的位置、颗粒尺寸和形状有关。 通过理论分析,建立了一个可用于描述散射信号幅度概率分布与颗粒系尺寸分布之间关系的数学模 型,对该模型的反演计算便可得到颗粒系的尺寸分布信息。为了避免求解过程中的病态系数矩阵问 题,将模型求解转化成了易于解决的最优化问题。仿真实例结果验证了该技术的可行性。     

一种简便的压阻测压方法

 介绍了用直流电压源和锰铜压力计测量压力的一种方法。该方法的测量电路非常简单，便于匹配，与以往传统的脉冲电源供电的测量方法相比，不仅可省去触发系统，而且由于流过压力计的电流很小（约20 mA），所产生的派生磁场对样品和飞片的磁化作用减少了两个数量级以上。同时此法也是一种低成本的压力测量方法。     

Fabrication of Al/AlO_x/Al junctions using pre-exposure technique at 30-keV e-beam voltage

We fabricate high-quality A1/A1O_x/A1 junctions using improved bridge and bridge-free techniques at 30-keV e-beam voltage,in which the length of undercut and the size of junction can be well controlled by the pre-exposure technique.The dose window is 5 times as large as that used in the usual Dolan bridge technique,making this technique much more robust.Similar results,comparable with those achieved using a 100-keV e-beam writer,are obtained,which indicate that the 30-keV e-beam writer could be an economic choice for the superconducting qubit fabrication.     

A simple technique to deposit molybdenum thin films

A simple technique is proposed for metallizing nonconductive objects. The technique, which is based on a plasma-induced dissociation of Mo(CO)₆ molecules, is inexpensive with no sophisticated instrument needed, and allows us to deposit fine grained, adherent thin films of molybdenum on nonrefractory substrates. It is believed that the technique possesses a variety of potential applications in laboratory works.     

Measurement of Reflected and Scattered Light for Monitoring Fluctuation of Structures

A laser spectroscopic technique for studying fluctuations of structural objects is presented, together with some results of our investigations including an observation of forced vibration of a refrigerator, intrinsic vibrations of buildings, and appearance of a fluctuation in rotational speed due to fatigue. An alternative detection technique which uses the scattered light for monitoring in place of the mirror-reflected beam is also presented. A leak of water out of a pipeline was detected with this method.

The results obtained with this laser spectroscopic technique should form a useful collection of data regarding fluctuation analysis of various objects.     

Measurements with an intensity meter of the acoustic power of a small machine in a room

A technique in which two closely spaced pressure microphones, a special purpose circuit, and a sound level meter are employed to measure acoustic intensity in octave bands, is used to estimate the intensity distribution around a small, 1200 electrical watt, machine situated in a room. The total acoustic power estimated therefrom is compared with that obtained by the conventional “direct field” method. The technique, which appears to be accurate over the range 250–400 Hz, produces values of intensity and power which are generally less than the “direct field” values. The difference tends to increase with frequency. A potential for source location application is indicated.     

Parallel phase-shifting dual-illumination phase unwrapping

We propose a single-shot phase unwrapping technique using a single wavelength and parallel phase-shifting interferometry. In the proposed technique, an object is illuminated by two laser beams, which are emitted from the same laser, and have different illumination angles and polarizations. Two types of object waves generated by the two beams are separately and simultaneously recorded by a polarization-imaging camera. In the path of the reference wave, an array of phase retarders is placed to implement the parallel phase-shifting technique. A highly accurate three-dimensional shape is reconstructed from a single hologram. We numerically simulated the proposed technique and conducted a preliminary experiment to verify its effectiveness. It was confirmed that millimeter-order height, which was several thousand times the wavelength of the laser, can be reconstructed by the proposed technique without wrapping.     

Ion-acoustic dressed soliton in electron-ion quantum plasma

Ion acoustic dressed soliton in an unmagnetized two-species electron-ion quantum plasma is studied. Using reductive perturbation technique, a higher order inhomogeneous (KdV-type) differential equation is derived for the second order correction. The nonsecular solution is obtained by using renormalization procedure. A new technique is used to obtain the particular solution of the higher order inhomogeneous equation which is found to be simpler compared to the technique used by previous investigators.     

应用脉冲加热/探测扫描技术进行表面下微尺度热结构探测过程的仿真

提出脉冲加热/探测扫描技术进行微尺度表面下热结构测量原理。通过对于复合材质试样表面受到脉冲热流作用时的瞬态热传导问题进行数值解析,得到各被扫描点的温度响应,根据对温度响应的数据处理结果给出热对比度的定义方式,进行扫描过程的仿真。根据仿真结果讨论分布状态,复合物深度,复合物与母材的物性比对于测量结果的影响。