Modified double-wedge-plate shearing interferometer for collimation testing

A modified configuration of the double-wedge-plate shearing interferometer for collimation testing is described. Results of the measurements to determine the setting sensitivity with this configuration are presented.     

Multiple-beam wedge-plate shear interferometer for collimation testing

We describe a modification of the wedge-plate shear interferometer for collimation testing. The surface of the wedge plate is coated to increase the reflectivity such that multiple-beam interference takes place resulting in sharp fringes. In addition to sharpening the fringes also tend to split when the test beam is noncollimated. This splitting has been used as a test criterion for collimation testing. Experimental results are presented.     

A modified approach for collimation testing using Lau interferometry

A modified approach for the collimation testing of an incoherent optical beam using the Lau effect coupled with moiré readout is proposed. In the experimental set-up a white-light incoherent source illuminates a coarse grating G_1. The collimating lens is mounted on a translation stage, so that the grating G₁ can be adjusted to be at the ‘in-focus’, ‘at-focus’ or ‘out-of-focus’ position. Grating G₂ and grating G₃ are mounted on a precision rotational stage and are so positioned that the lines of the gratings make a small but equal and opposite angle with the vertical. The inclination angle of the resulting moiré fringe demonstrates the quality of collimation of optical beam. The proposed technique can also be conveniently used for measurement of the focal length of a collimating lens, at a very low cost.     

Wave-front analysis method of circular aperture sampling for collimation testing

A new type of wave-front analysis method for the collimation testing of laser beams is proposed. A concept of wave-front height is defined, and, on this basis, the wave-front analysis method of circular aperture sampling is introduced. The wave-front height of the tested noncollimated wave can be estimated from the distance between two identical fiducial diffraction planes of the sampled wave, and then the divergence is determined. The design is detailed, and the experiment is demonstrated. The principle and experiment results of the method are presented. Owing to the simplicity of the method and its low cost, it is a promising method for checking the collimation of a laser beam with a large divergence.     

Automated collimation testing by incorporating the Fourier transform method in Talbot interferometry

In this paper, we report an automated technique for collimation testing by incorporating Fourier fringe analysis of the recorded interferograms in Talbot interferometry. The triangular profile of Talbot interferometric fringes has been recorded using a CCD and computer system. The interferograms corresponding to the in-focus, at-focus, and out-of-focus positions of the collimating lens have been recorded. Direct phase measurement using the Fourier transform method has been used for detection of collimation positions. Good accuracy and precision in measurement have been achieved.     

Improved cytotoxicity testing of magnesium materials

Metallic magnesium (Mg) and its alloys are highly suitable for medical applications as biocompatible and biodegradable implant materials. Magnesium has mechanical properties similar to bone, stimulates bone regeneration, is an essential non-toxic element for the human body and degrades completely within the body environment. In consequence, magnesium is a promising candidate as implant material for orthopaedic applications. Protocols using the guideline of current ISO standards should be carefully evaluated when applying them for the characterization of the cytotoxic potential of degradable magnesium materials. For as-cast material we recommend using 10 times more extraction medium than recommended by the ISO standards to obtain reasonable results for reliable cytotoxicity rankings of degradable materials in vitro. In addition primary isolated human osteoblasts or mesenchymal stem cells should be used to test magnesium materials.     

用于微米尺寸检测技术的涡流测量装置

根据高频涡流原理的集肤效应,研制出非接触式多通道微米尺寸测量系统。本文论述系统的组成、技术的原理、实验的测试结果,并得到小于2μm的误差结果,从而说明该系统满足精密零件的在线筛选检测的要求,在全自动生产线上有广阔的应用前景。     

Lau effect and beam collimation

Abstract

We report a new phenomenon in showing that the rotation sensitivity of Lau fringes depends not only on spatial coherence of the illumination used but also on its convergence or divergence. This finding could be usefully applied to beam collimation and focal length measurement.     

Improved technique for measuring small angles

Based on the total-internal-reflection effect and heterodyne interferometry, an improved technique for measuring small angles is proposed. This technique not only expands the measurement range but it also improves measurement performances. Its validity is demonstrated.     

Improved impact-echo technique by signal processing

An experimental study was performed to modify the conventional impact-echo technique to detect small diameter spherical voids in concrete. High velocity impact of steel balls was used to generate the high frequency waves in concrete necessary for detection of small voids. Elastodynamic wave propagation in concrete, type of impact source, and the size of the flaw that can be detected were studied. These laboratory studies were carried out on a 4 in. (10.2 cm) thick 4 ft. × 4 ft. (1.22 m × 1.22 m) concrete slab that contained a variety of artificial spherical flaws embedded at known locations. Analysis of the frequency spectrum of the response of the slab was used to determine the slab's thickness and presence of voids.Signal processing techniques were applied for a better interpretation of the slab's response. Autocorrelation and cross-correlation algorithms were used to determine the characteristics of the slab at different locations. The problems associated with determination of flaws and voids in concrete have been delineated. Some practical and easy to implement solutions have been proposed and ways of using the impact-echo technique more efficiently for field applications have been discussed.     

One-dimensional collimation of laser array outputs

We consider a computer-generated hologram for the one-dimensional collimation in x of the output from a linear laser-diode array in y. Our concern is to produce one-dimensional pencil beams from each laser diode with small cross talk between the output from the separate laser diodes. Such outputs can be used in matrix-vector, neural net, and interconnection applications. The efficiency and the design of the computer-generated hologram are detailed, and initial optical laboratory results with an electron-beam recorded computer-generated hologram are presented.     

A technique for dynamic tensile testing of metals

A technique is described for obtaining full dynamic stress/strain curves in tension up to strain rates of 100^s-1. In conjunction with a high speed servo-hydraulic machine, a low inertia extensometer has been developed to facilitate measurement of specimen tensile strain up to fracture.
The benefits of the technique are highlighted in relation to currently available methods for dynamic stress/strain measurement.     

生物安全柜性能检测的依据及关键技术

针对目前国内生物安全柜性能检测的依据缺乏一致性,它们的分类分级、检测参数和检测方法不尽相同,造成检测结果不具备可比性,在参照国际和国内相关标准(欧盟EN12469:2000、美国NSF/ANSJ 49-2002、中国JG 170-2005和YY 0569-2005)的基础上,结合国内实际情况,对生物安全柜性能检测方法进行阐述.该方法在保证检测质量的前提下,简化了检测项目,提高可操作性,并对以往容易忽视的检测项目,例如紫外线强度、换气次数等参数,提出了具体的量化指标.此外,着重对气流控制、气流安全性能区、过滤效果、气密性等检测要点及关键技术进行了详细说明,以供相关科技工作者参考借鉴.     

Reprint of: Improved cytotoxicity testing of magnesium materials

Metallic magnesium (Mg) and its alloys are highly suitable for medical applications as biocompatible and biodegradable implant materials. Magnesium has mechanical properties similar to bone, stimulates bone regeneration, is an essential non-toxic element for the human body and degrades completely within the body environment. In consequence, magnesium is a promising candidate as implant material for orthopaedic applications. Protocols using the guideline of current ISO standards should be carefully evaluated when applying them for the characterization of the cytotoxic potential of degradable magnesium materials. For as-cast material we recommend using 10 times more extraction medium than recommended by the ISO standards to obtain reasonable results for reliable cytotoxicity rankings of degradable materials in vitro. In addition primary isolated human osteoblasts or mesenchymal stem cells should be used to test magnesium materials.     

地震灾区电机应急测试技术

针对灾后电机可靠性快速检测的需求,从生产实践中遴选了可用于现场快速测试电机电气和机械性能的检测方法,并给出和完善检测的参数和判别指标。所给出的检测项目覆盖了90%的电机故障,该方法也可用于电机的日常检验、维护和故障诊断。     

An analytical and experimental technique for testing grp domes

This paper describes the analytical and experimental techniques which were applied to a smooth grp dome under a system of gravity loads to obtain stresses and deflections at various points within the structure. In addition, the experimental results for this dome are compared with those for a scallop one of the same dimensions to illustrate the increase in stiffness of the latter over the former. The analytical analysis is directly related to a skeletal framework with a modification to give the stress levels within the continuum structure. It has been shown that the deflections of the scallop dome when under load are less than those of the smooth dome under an identical load system but the meridian and latitude stresses are generally 20% higher although the absolute values of stresses are low. The analytical structures are stiffer than the experimental and indicate a lower value of stress level.     

Resonant tunneling in nanocolumns improved by quantum collimation

We report on a quantum collimation effect based on surface depletion regions in AlAs/GaAs nanocolumns with an embedded resonant tunneling structure. The considered MBE-grown nanodevices have been fabricated by means of a top-down approach that employs a reproducible lithographic definition of the vertical nanocolumns. By analyzing the scaling properties of these nanodevices, we discuss how a collimation effect due to a saddle point in the confining potential can explain an improved device performance of the ultimately scaled structures at room temperature.     

用于光纤多普勒测振的远距离光纤准直系统

为了解决光纤多普勒测振仪远距离非接触测量物体振动时,信号偏弱、过零点波形凌乱、难于解调的问题,本文提出了一种新型光纤准直系统。本系统主要采用在小型C-lens光纤准直器后端增加整形系统并借助ZEMAX软件对高斯光束进行准直并优化,通过对光纤准直系统成品进行耦合测试实验,使用C-lens准直器与光纤准直系统进行信号耦合效率的测试对比。实验结果表明：改进后的准直系统能够满足2 m的工作距离,空间返回光耦合效率最大能达到6.3%,极大地提升了多普勒信号的对比度,提高了远距离光纤多普勒测振仪对振动的测量精度。

     

An improved range-resolution pulse-echo technique by means ofvectorial-network-analyzer-based frequency-domain testing

A particular procedure is suggested to implement a high-range-resolution pulse-echo ultrasound technique by means of a frequency-domain exploration of the tested device and a successive Fourier inverse transformation of the measured data. The improvement with respect to conventional methods is estimated, and an experimental setup based on the use of a commercially available vectorial network analyzer is presented