Showing papers in "Optics and Lasers in Engineering in 1992"

TL;DR: In this article, a speckle pattern is formed when a rough surface is illuminated with coherent light; the properties of this pattern can be employed for surface-roughness measurement.

TL;DR: In this paper, the first full-scale fiber optic damage assessment test system in the form of a composite aircraft leading edge and the fabrication, characterization and evaluation of the first fiber optic strain rosette was shown to be capable of mapping the strain tensor from within composite materials.

TL;DR: In this paper, two fiber optic-based laser anemometers for flow measurement inside turbomachinery are presented, one is used to measure flows in an axial compressor at velocities up to 40 ms−1 and the other is a 3D laser Doppler velocimeter that uses a technique of oblique backscatter to allow sequential measurement of the three orthogonal velocity components.

TL;DR: In this article, the authors examined the measurement of the penetration speed during CO2 laser cutting of stainless steel workpieces and concluded that the cut quality improves when penetration speed is at a maximum.

TL;DR: In this article, a theoretical comparison of the accuracy in interpreting fringe data as gradients (geometric interpretation) and finite differences (physical interpretation) of deformations associated with a K-dominant stress field near the tip of a stationary crack is conducted.

TL;DR: In this article, a throttle level angle (TLA) sensing system is described that utilizes a capacitance based rotary position transducer that is powered and interrogated via light from a single multimode optical fiber.

TL;DR: The general concepts of underwater holography are outlined and a resume is given of the work undertaken in the past, the problems experienced and their solution and an indication of the general direction leading to the establishment of holographY as a unique method of subsea inspection.

TL;DR: In this article, the specular reflectance of cold-rolled aluminum surface is studied using a fiber optic system and an approximation for the determination of surface roughness is presented. But the results are limited.

TL;DR: In this article, a 50 cm confocal Fabry-Perot interferometer was used to analyze speckle from back-scattered laser light, which can be used to detect 4-mm diameter drill holes with resolutions of ± 0·5 mm.

TL;DR: In this article, a prototype sensor for surface heat transfer measurements based on a miniature fiber Fabry-Perot (FFP) interferometer is described, which consists of a short length of single mode optical fibre (∼ 3 mm) to which low reflectivity coatings have been applied at each end.

TL;DR: In this article, the authors employed dynamic moire interferometry to study the localized impact response of a thick composite plate, which consists of 0/90/03 graphite fibers in a Hercules AS4/3501-6 carbon/graphite pre-preg.

TL;DR: A prototype system has been developed which generates equal depth contours of undersea objects and has applications in sizing, orientation and ranging and an advantage of this system is that the entire field is continously illuminated, and the moire contours and images are formed at video rates.

TL;DR: In this paper, an intrinsic temperature sensor based on a local refractive index variation of the constituent material as a function of both temperature and curvature is proposed, which operates by an organized competition between a predetermined strain obtained by bending the fiber with a known bending radius and a temperature-indiced strain that will modulate the waveguide.

TL;DR: Three experiments employing PSD and OT techniques for monitoring surface profiles in mechanical, photographic, and automotive fields are presented and are sources for understanding the potential of these detectors as simple, efficient, and readily available means of automatic inspection in a wide range of fields of application.

TL;DR: In this paper a versatile interpolation method is presented which allows the specification of the data field onto an arbitrary grid and the local partial derivatives can be evaluated from the local functional representation which is continuous up to the second derivative throughout the region of interest.

TL;DR: In this paper, the authors present experiments with internal gravity waves generated by a body oscillating around a fixed position and a test body moving with constant speed vertically through the stratified brine.

TL;DR: In this article, a review of the LDA/PDA spectrum processor with a maximum likelihood criterion has been given, including the algorithm, architecture structure and performance, and the advantages of the developed computer-based system are described.

TL;DR: A generalized iterative approach to the tomographic reconstruction of strongly refracting fields is proposed, where two enhanced schemes are developed by making particular selections for the arbitrary operator, and a 1 -D boundary layer type field is reconstructed from numerically simulated interferometric data.

TL;DR: In this article, the amplitude variations of Bessel frequency components contained in the photodetected output of a phase modulated two-beam interferometer were used for displacement sensing.

TL;DR: In this article, the authors describe three fiber-coupled sensors presently under development at the Boeing High Technology Center including a single track analog sensor, a sensor based on weighted number system encoding, and an FMCW laser radar sensor.

TL;DR: In this article, particle image velocimetry (PIV) was used to examine the hydrodynamics of wave-current interaction in a sea state consisting of a mean current flow mixed with freely propagating gravity waves.

TL;DR: In this article, an experimental study of the fluid motion induced in the grooves by an adjacent stream is presented, where the structure of the vortex system within the enclosures, its dependancy on the aspect ratios of the geometry and the type of oscillation generated are examined.

TL;DR: In this article, an all-fibre optical system for interrogation and detection of the vibrations of a silicon micro-resonator is reported, where metal-coated silicon microresonators are excited by intensity modulated laser light delivered through an optical fiber, while the vibration of the resonators is detected by an optical fibre interferometer.

TL;DR: In this article, a new statistical method has been developed for the detection, recognition, and measurement of profiles of light beams that are (much) smaller than the diameter of the elementary scanning windows.

TL;DR: In this article, the authors compared laser Doppler Anemometry (LDA) and Particle Image Velocimetry (PIV) velocity measurement techniques in two experimental situations and their results compared.

TL;DR: The convoluted Hanning function appears to be an excellent candidate for tomographic reconstruction of continuous phase objects from multidirectional projection interfrograms with limited data points, and outperforms the conventional methods including the grid method and convolution back-projection.

TL;DR: The application of interferometry techniques to analysis of aerodynamic flows on rotorcraft is reviewed, with emphasis on those studies which give insight into the character of the complex flows on helicopter rotor blades as mentioned in this paper.