Showing papers in "Optics and Lasers in Engineering in 1998"

TL;DR: In this article, a method of measuring surface roughness of flat lapped, ground and polished metallic surfaces, by the far-field speckle contrast method is presented in this paper.

TL;DR: Advancements in the last two decades for data acquisition in digital photoelasticity have been brought out in this paper and a need to capture the images in colour is indicated for full automation of data acquisition.

TL;DR: In this paper, the characteristics of a laser-induced shock wave under confining conditions are studied, such as amplitude, width, and duration, and the relationship between the pressures and the acoustic impedance of confining materials, which somewhat agrees with the theoretical calculation.

TL;DR: In this paper, an experiment was conducted to irradiate the AISI 4142 steel surface by an Nd-YAG laser and micro-photography and EDS analysis of the heated regions were carried out.

TL;DR: In this paper, a digital speckle pattern shearing interferometry (DSPI) is described as a robust measuring method due to its simple optical setup and the relative insensitivity against ambient noise.

TL;DR: In this article, a diffraction relief fabrication without substrate etching is proposed, where step-wise relief is produced by the multiple applying of photoresist layers (layer over the layer), previously exposed to light through the appropriate photomasks and subject to all conventional stages of resist processing.

TL;DR: These applications involve two techniques for the measurement of 3D deformation fields, measurement of the in-plane strain field components using defocused laser speckle, and measurement of object shape.

TL;DR: In this paper, a whole-field speckle method is employed to determine metallic surface roughness, and six sets of surfaces prepared by a spark-erosion process with roughness ranging from 0·4−12·5μm have been tested.

TL;DR: In this article, a digital projection grating method for full field measurement of out-of-plane deformation and shape of an object is presented, where two grating patterns are captured by a CCD camera and stored in a computer.

TL;DR: In this article, it was shown that the carrier frequency is approximately equal to the average of the first difference of the phase before attaining the phase map, and then the average was calculated to get the phase maps without carrier frequency.

TL;DR: It is emphasized that this method can be applicable to time varying phenomena in which good repeatability and reproducibility of experiments are not expected, since multiple exposures are not necessary for sufficient data acquisition in the completion of stress analysis.

TL;DR: In this article, three methods of fringe thinning algorithms are considered for the reconstruction of the temperature field in the fluid layer in a CCD camera along with an image processing system, and the first algorithm is programmable and is based on the search of minimum intensity within the dark bands of the fringe system.

TL;DR: In this paper, a method which employs an integrating sphere and a single-wavelength (1.6μm) pyrometer for measuring the spectral effective emissivities of superalloys in the temperature range (650-1050°C) is described.

TL;DR: In this article, a two-dimensional photoelastic method for the analysis of fringe order and the principal direction of birefringence from a single image combining an elliptically polarized white light and color image processing is demonstrated.

TL;DR: In this paper, a laser displacement meter is used for direct multi-purpose sensing of milling tool conditions, which can be interpreted for identification of tool geometry, tool whirling, or vibration.

TL;DR: In this paper, a cylindrical surface is reconstructed by using the stereo vision and the error of the measurement is analyzed using the nonlinear optimization technique to obtain a set of parameters: the direction cosine of the centerline of a cylinder, the point of intersection of the centreline of the cylinder with the XZ-plane, and the radius of the cylinders.

TL;DR: In this paper, the effects of momentum and gas-liquid interface shear stress, due to the assisting gas jet, are considered in CO2 laser gas-assisted cutting process.

TL;DR: In this paper, the authors discuss methods for the generation of desired phase distributions based on the representation of DOEs as an array of diffraction gratings with different direction of grooves and different periods.

TL;DR: In this article, the white light speckle method was used to study the movement of large objects on a glacier to monitor their movement using sunlight for illumination of natural speckles on the glacier.

TL;DR: A space mapping method using the least-squares algorithm is presented for the probe calibration and profile measurement and can determine the 3-D profile of an object with an accuracy of 60 μm.

TL;DR: In this paper, an optical configuration of a coherent correlator with a spatial filter consisting of segmentized diffraction gratings is proposed for fingerprint identification. But it is only the information related to the angular spectrum distribution that appears to be essential.

TL;DR: In this paper, the authors compare experimental data for a laser spot weld on a ceramic to the solution from an adaptive finite element model of the system, which necessarily includes numerous simplifications.

TL;DR: In this article, the authors report on a recent experimental study of a closely spaced pair of jets which may be of the same or different jet velocities and which interact with each other, with a crossflow and with an opposite solid wall.

TL;DR: A novel iterative two-parameter algorithm for the design of diffractive optical elements (DOE) is discussed and is shown to be the generalization of a number of familiar algorithms for designing DOEs.

TL;DR: The parallel and distributed processing nature of Tapestry cellular Automata is shown to be able to keep the merits of traditional Cellular Automata algorithm while taking advantage of the rapid advancement of personal computers such as distributed computing over internet or intranet and multi-tasks operating environment.

TL;DR: A system employing a pulsed laser diode, uniform intensity line generating optics and a high-speed TDI imager for recording structured light patterns from rotating cylindrical objects is illustrated.

TL;DR: In this paper, a gradient algorithm is proposed for design of phase diffractive optical elements (DOEs) that can form the light beams being effectively a superposition of a small number of nonradially symmetric Gauss-Laguerre modes with a preset energy contribution of each mode.

TL;DR: An automatic human face recognition system in which several well-known technologies, such as the affine transform, the histogram equalization, the spatial encoding, and the hit–miss transform are incorporated in a new form.

TL;DR: In this article, an experiment to visualize the speckle pattern motions received by the photodetectors during these vibration conditions is presented, and theories regarding the source(s) of the "noise" are developed.

TL;DR: In this article, a method that uses three light-field isoclinic images and the associated light field unloaded model (or white) images for whole-field digital determination of the principal stress directions in photoelasticity is presented.