Showing papers in "Optics and Lasers in Engineering in 1997"

TL;DR: This paper reviews the past and current literature devoted to the applications of 3D anthropometry because true 3D scanning of the complete human body is fast becoming a reality.

TL;DR: In this article, a double-pulsed holographic system is described where two separate holograms of an object under test are recorded within a few microseconds using a CCD-camera and stored in a frame grabber.

TL;DR: In this article, a new formula for calculating the phase in interferometric measurements by the phase-stepping method was proposed, which utilizes equal phase steps with an arbitrary value.

TL;DR: In this article, the authors describe a feasibility study of a high magnification full field deformation measurement system, consisting of an image acquiring and analysis system and an optical metallurgical microscope, which can be used to determine in-plane surface displacement fields at magnifications up to 2000 pixels/mm.

TL;DR: In this paper, a simple optical set-up with three light sources arranged in a particular symmetry and an associated procedure which allows accurate isolation of all six displacement derivatives which can contribute to the formation of fringes in image-shearing speckle pattern interferometry is presented.

TL;DR: This paper describes a project involving computer assisted measurement extraction from a three-dimensional (3D) noncontact fullbody scan, and describes briefly the research plan and provides details on the measurement extraction software currently being developed.

TL;DR: In this article, the authors used an injection seeded, frequency doubled Nd:YAG laser tuned to an absorption band of iodine to measure flow properties in a small supersonic wind tunnel.

TL;DR: In this article, a modified Fourier transform profilometry (MFTP) is described for the measurement of 3D steep object shapes, which gets rid of the disadvantage of IFTP by utilizing the nature of FTP.

TL;DR: In this article, the deformation due to the relief of stress produced by a drilled hole or a ball indentation is rapidly measured by digital shearography, which does not require mounting strain gages/transducers.

TL;DR: While both methods enjoy the advantages of being full-field and non-contacting, digital shearography has been proven to be more practical than TV-holography because it employs a simpler set-up and does not require special vibration isolation.

TL;DR: In this paper, the effect of speckle integration implicit in digitization by pixels of finite size is considered using computer-generated specckle patterns, and it is shown that the phase errors decrease monotonically with decreasing speckles diameter.

TL;DR: In this article, an optical corrosion meter was built based on a mathematical model relating surface and bulk behaviours of metals in aqueous solution, which was established based on principles of holographic interferometry for measuring microsurface dissolution, and on those of electrochemistry for measuring the bulk electronic current.

TL;DR: Holographic-hole drilling is a method developed for the rapid determination of residual stresses from an optical interference fringe pattern as mentioned in this paper, where a small diameter blind hole is drilled into a part containing residual stresses, and the displacements caused by localized stress relief are registered by real-time holographic interferometry.

TL;DR: Several applications of the Murty interferometer in the testing of optical systems and components are reviewed in this paper, including measurement of refractive indices of simple lenses, measurement of birefringence of optical materials, thermal expansion coefficient of metallic bars and optical distortion in transparencies or glass windows.

TL;DR: A number of techniques have been proposed during the past twenty years that have the common purpose of automating photoelastic fringe analysis, including spectral contents analysis, phase-shifting or stepping and Fourier transform procedures, and all of the analytical methods suffer similar disadvantages.

TL;DR: In this article, the speckle fields generated by plant specimens irradiated by laser light have been studied using a pointwise method, based on multi-scattering theory, and the results suggest that both the identity of the botanical specimen and the site at which measurements are taken are likely to critically affect the observation or otherwise of temporal fluctuations of laser speckles.

TL;DR: In this paper, a technique for the slope measurement of objects using an electronic shearography system is presented, where a laser diode is modulated to produce two wavelengths on successive image frames.

TL;DR: This paper investigates whether one or all of the image planes can be thought of as behaving like an optical filter: with the hardware used, the green channel is found to behave in this way and this idea is then used to extend the phase-shifting technique to colour domain.

TL;DR: In this paper, an intensity-based fiber-optic displacement sensor has been developed and tested for static and dynamic response for small displacements, the sensor shows excellent frequency response up to 10 kHz.

TL;DR: In this article, a portable, single component Doppler global velocimetry (DGV) head, based around a wavelength-stabilised argonion laser and a fast digital image-processing system, is described.

TL;DR: Using digital image processing, images generated by a phase-stepped Shearography are processed by a deconvolution technique, resulting in quantitative displacement data.

TL;DR: In this paper, a portable ESPI system consisting of a lightweight optical head mounted on a tripod, a semiconductor laser source, a PC unit for acquisition and processing of the speckle images, and a monitor for displaying the interferometric fringes in real time is presented.

TL;DR: Based upon observation of the experimental results, a new optical solder joint inspection system is found to show good performance for inspection of solder joint defects.

TL;DR: In this article, a 1 × 4 single mode optical fiber beamsplitter is employed to split the laser beam into four beams of equal intensity, and the optical fibers are equal in length for each pair, but are not equal between two pairs.

TL;DR: A new phase unwrapping method that has the advantage of unwrapped of phase distribution with severe noise such as those obtained in speckle interferometry is proposed and works quite well even when the human eye cannot recognize clearly the phase jumps due to noise.

TL;DR: In this paper, an electronic pattern speckle shearing interferometer is used to measure the spatial derivatives of the surface topography of an arbitrary shaped object, and the sensitivity of the contour planes can be varied over a wide range.

TL;DR: In this paper, an analysis of the out-of-plane shearing interferometer has been performed, which shows that production of in-plane strain partial derivatives is possible, which are not affected by out ofplane displacement function components.

TL;DR: In this article, an interferometric strain rosette (ISR) technique is extended to residual stress measurements, which is based on diffraction and interference of laser light reflected from three micro-indentations depressed in a specimen surface.

TL;DR: In this paper, the fringe spacing variations in the measuring volume of a differential LDA system are analyzed and the fringe patterns are obtained for different locations of beam waists, and it is found that when the incident beams are sharply focused and a large beam cross-angle is used to obtain high spatial resolution, fringe gradients occur along both the x- and z-directions.

TL;DR: In this paper, the authors demonstrate that digital shearography can tolerate much greater rigid body translation than a speckle size as predicted by the conventional speckles decorrelation theory.