修正的CES模型与印度经济增长分析

通过对CES模型的修正，反映技术水平对一国经济增长的影响，并将修正后的模型用于对印度过去近30年经济增长的实际分析，得出结论：20世纪90年代以来，印度经济增长过程中在劳动技术水平有所提高的同时，资本技术水平却较为显著地下降，因此印度政府应深化经济体制改革，提高资本的使用效率。     

光纤损耗测试仪器的校准

本文从计量检定角度提出一种光纤损耗测试仪的校准方法。利用光纤衰减器、Y型光纤分路器及标准光功率计,可评价损耗测试仪的精度等级。方法简单且利于量值传递。     

Phase locked loop profilometry

An innovative technique for obtaining automatic three-dimensional shape information of a diffuse surface is presented. The technique is based on a new approach of phase measuring from a fringe pattern. The target to be studied is first modulated by projecting a linear grating onto its surface. The linear fringes are deformed according to the surface shape. Demodulation is carried out by determining the phase of these deformed fringes using a novel digital phase locked loop demodulation algorithm. The technique has the main advantage that the traditional phase unwrapping process is not required. The phase is determined continuously as the algorithm scans the two-dimensional fringe pattern. Owing to its sequential nature, this phase detection technique can be implemented using a special purpose video processor for phase determination at video rates, making it a very fast algorithm. The algorithm along with experimental results of real surface profiles are presented.     

半导体激光器及其在干涉计量中的应用

本文介绍了半导体激光器的典型特性,探讨了用其相干长度进行干涉计量的新方法,并进行了眼球光学长度的测量的实验。     

A preliminary study of the distribution of plankton using hologrammetry

The distribution and dynamics of particles in the aquatic environment play an important role in the modelling of bio-geochemical processes. Previous work on the measurement of such particles, which vary in size from tens of micrometres (individual cells) to several centimetres (aggregates such as ‘marine snow’), has mainly used electronic counting or conventional photography coupled with image analysis. Here we report on an initial study of the use of holographic mensuration, otherwise known as hologrammetry, for the enumeration, sizing and spatial distribution determination of plankton. We present results on imaging plankton in water tanks using both in-line and off-axis pulsed-laser holography. In this work, we have recorded in-line holograms in a volume of 2400 cm³ of water with a resolution of better than 20 μm and off-axis holograms in a volume of 36000 cm³ with a resolution of 140 μm. In both cases, identifiable images of plankton were obtained and precise spatial coordinates determined from the in-line holograms.     

Speckle shearography using a multiband light source

Applications for optical metrology usually use lasers as light sources, because of the excellent spatial and temporal coherence of the emitted light. By comparison, the demands of speckle shearography concerning the coherence of the light source are low. This enables certain white-light sources to be an option.

In this paper, the feasibility of low coherence shearography is shown. For this purpose an experimental setup is designed, composed of a mercury arc lamp, a spatial filter and a Michelson interferometer. With respect to speckle shearography, important characteristics of the light source are described and the mercury arc lamp is shown to be suitable. Finally, some experimental investigations of an object under load are presented.     

Four-pulse interferometric recordings of transient events by pulsed TV holography

With traditional double-pulsed holographic interferometry or pulsed TV holography, the experiment usually has to be repeated to allow the recording of a time sequence of interferograms of the event. With the proposed technique a sequence of four interferograms of a solitary transient event is measured. A twin oscillator, injection-seeded, pulsed Nd:YAG laser is incorporated into a pulsed TV holography set-up. With orthogonal polarisation and double pulsing of each of the two channels of the laser, four pulses are recorded on two separate CCD-frames. Four interferograms of a laser-impacted plate obtained from the same experiment, show how the bending waves develop and propagate in the plate.     

Moiré topography in odontology

For several decades, measurement of optical techniques has been used in different branches of science and technology. One of these techniques is the so-called moiré topography (MT) that enables the accurate measurement of different parts of the human body topography. This investigation presents the measurement of topographies of teeth and gums using an automated system of shadow moiré and the phase shift method in an original way. The fringe patterns used to compute the shape and the shape matrix itself are presented in the article. The phase shift method ensures precisions up to the order of microns. Advantages and disadvantages of using the MT are included. Besides, some positive and negative aspects concerned with the implementation of this technique in odontology are shown in the article.     

Effect of primary aberrations on transverse displacement of laser speckle patterns

The effect of primary aberrations on the transverse displacement of laser speckle patterns in the real image plane due to transverse displacement of an object is studied in the approximation of Fourier optics. Primary aberrations cause: (i) a complementary displacement of the speckle pattern; and (ii) its decorrelation. The main features of complementary displacements are as follows: (a) the overall complementary displacement is the sum of complementary displacements caused by each one of the primary aberrations; (b) the complementary displacement caused by the spherical aberration is uniform in the image plane; (c) spherical aberration and curvature of field cause complementary displacements that are parallel to the object's displacement; (d) the complementary displacement caused by distortion is always zero on the optical axis; (e) the complementary displacement caused by distortion is free of decorrelation; (f) complementary displacements are non-proportional to the object's displacement; and (g) complementary displacements depend on the position of the illuminating source with the exception of the complementary displacement caused by distortion.     

电子散斑归一化互相关法测位移

把粗糙物体表面受到相干光照明时产生的散斑场看作是一个稳态随机信号,在此基础上,本文提出了一种能做到大量程,高精度位移测量的新方法——电子散斑归一化互相关法测位移或称电子散斑照相法测位移.该法实质上是借助数字图像处理技术,通过物体位移前后二个散斑场之间的相关性来进行位移测量方法的发展.文中给出了理论分析和实验系统.实验结果表明,该法有诸如准实时,大量程(毫米级),高精度和线性可靠等优点.