Since 1975 McCarthy and Low have conducted a program of Michelson spatial interferometry at infrared wavelengths, measuring a large number of evolved stars and protostellar objects. This dissertation discusses the development of an infrared speckle interferometer which was used to extend those observations. This instrument uses a modified version of the technique pioneered by Sibille, Chelli, and Lena. The secondary mirror is used to scan the image across a narrow slit. Each scan is fourier transformed, and the modulii squared of many such transforms are coadded. Both the object of interest and a point source are observed. The square root of the ratio of their power spectra is the visibility as defined by Michelson. This system was assembled for the most part with existing equipment and the design should be readily adaptable to other observatories. Initial tests were made with the 154 cm telescope of the University of Arizona since it had a preexisting mechanism for scanning the secondary. However most of the observations were carried out with the University's 229 cm telescope. A new linear servo was added to the existing hard-stop chopper for this telescope's f/45 secondary. Three detector systems were used to provide wavelength coverage from 2 to 12 microns. An N₂ cooled InSb and a He cooled bolometer were available from the Michelson program. In addition a high sensitivity He cooled InSb detector from the Steward Observatory FTS was used. Slits with an angular size of λ/2D, where D is the telescope diameter were placed at the focal plane in the dewar. The narrow slit results in diffraction losses when used with conventional dewar optics. The loss could be eliminated with optics optimized for this application. However even with the loss, a large number of objects could be observed. Test results at 2 microns were obtained for a double star, the asteroids Vesta and Ceres, and the Galilean satellites Ganymede and Callisto, The protostellar objects W3 IRS 5, S140, and Mon R2 IRS 3 were resolved. The separation, orientation, and relative brightness of the two components IRS 5 were measured at 5 microns. The separation is 1.26" ±0.06 and the position angle is 37° ±5. The brightness ratio is approximately 0.59. S140 and Mon R2 IRS 3 were observed at 2 microns. S140 shows some indication of an extended region of greater than 1" contributing half the flux. IRS 3 has a size of approximately 1" but the data is too noisy for an exact fit. Upper size limits were determined for BN, GL 490, GL 2591, and NGC 2264 IRS. A large number of evolved stars were observed. The size of the shell around Alpha Ori was found to be ∼4" at 11 microns. Observations were obtained for IRC + 10216 at 2, 5, 8, and 11 microns which further define the asymmetrical shape of this object. Observations were also obtained for VY CMa. Upper size limits were established for Omicron Ceti, IRC + 10011, RX Boo, R Hyd, W Hyd, and CIT 6.

No description available.

Speckle noise is an integral part of any laser projection display because it is the nature of laser (coherent) illumination to form interference patterns with high visibility. The granularity of the image due to the speckle formed on the viewer's retina degrades the image quality, thus stimulating the need for speckle reduction techniques applied to laser displays. An instrument to measure image plane speckle contrast was built based on a linear CCD detector array interfaced to an LSI-11 microcomputer. Speckle reduction techniques were then evaluated by comparing the contrast obtained with each method. The effect of the spatial frequency response (MTF) on the measured contrast was studied, along with the statistical significance of the measurement which is limited by the finite sample space of 1024 detector pixels per CCD frame. The lowering of the contrast due to the array MTF can be minimized by working at extremely high F numbers (> 100). The sample space can be widened by taking more than one frame of data and treating all the frames as a single data set. Techniques to reduce speckle noise in laser displays fall into two broad categories: reducing the coherence of light forming the speckle, and incoherently adding multiple uncorrelated (or partially correlated) speckle patterns. The first technique (effective only for monochromatic displays) was implemented by coating a screen with various dyes, phosphors, or fluorescent paints. Using the 514 nm line from an Argon laser, the contrast can be reduced by almost 30% by spraying a thin layer of fluorescent paint on the screen. More speckle reduction can be achieved with an accompanying loss in image brightness. The second technique involved creating a multiplicity of partially correlated speckle patterns that appear from the same position on the screen over the integration period of the eye. The different speckle patterns are produced by changing the angle of illumination while keeping a portion of the laser spot focused on the same point on the screen. The scan angle method (applicable to multi-color displays), can be implemented by properly synchronizing an acousto-optic modulator with the scan optics, and imaging the modulator on the screen. Using a beaded screen and a reasonable laser dither of 10 millirads, the contrast can be reduced by half.

Abstract This research report details the design, construction, implementation and optimization of a quantitative movable flow visualization technique named Electronic Speckle Pattern Interferometry (ESPI). ESPI is a powerful visualisation technique that can allow for full flowfield analysis. It is thus possible to quantitatively determine the refractive index variation and hence the density variation in a compressible gas flow. Complementary results between previous work done and the current work shows the integrity of ESPI results Flowfields that were investigated included – candle flame, axis symmetric and nonaxis symmetric nozzles. Due to advanced CCD technology, there have been improvements in the overall image quality. Post processing of the images produced clearer images and hence better results. The technique was applied on multiple test rigs, proving its versatility

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (p. [125]-135).

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (p. 145-151).

This research demonstrates the feasibility of a full-field photographic method for remotely measuring the movement of large deforming objects. 'Large objects' could include civil engineering structures such as dam walls, buildings and bridges, and geological phenomena such as glaciers. Such structures must be examined in situ and preferably by a non contacting method. The objective is to measure motion from time lapsed photographs of the moving object. The method is based on speckle photography which is a well developed optical metrology technique for deformation measurement of engineering structures in laboratory conditions. Its application to large scale structures illuminated in sunlight at high imaging demagnifications has demanded some significant extensions and modifications to the technique. Imaging these large objects offers a unique set of challenges which include the establishment of rigid tripods from which to take the time lapsed photographs in rugged glacial terrain, the variation of illumination in terms of both quality and angle of incidence, imaging through several kilometres of turbulent atmosphere and recording the signature texture of the object surface onto film at high imaging demagnifications. The effects of these factors are considered both conceptually and experimentally, providing fundamental understanding of the problem. Displacement analysis is performed primarily by interrogation of time lapsed negative pairs using an unexpanded laser beam, as is generally the case in speckle photography. An automated system is developed to make practical the analysis of multiple points in the field of view. In parallel, a new digital technique is introduced where displacement results are obtained by pattern matching in digital versions of the speckle images. This analysis method is shown to be highly suitable for the application to glacier flow. Registration of the pair of time lapsed images is performed by calculating the affine transform describing the image misalignment (introduced at either the recording or analysis stage) within the non-deforming areas of the field of view. Use of this novel technique allows pairs of single exposures, rather than double exposures, to be examined, and it also increases the sensitivity of measurement. Two dimensional motion fields representing glacier flow are presented, leading to the conclusion that the technique is feasible in sunlight illumination, for a variety of glacial surface types and at high imaging demagnifications.

L’évolution du champ de localisation des déformations plastiques des métaux ductiles a été suivie par interférométrie de granularité laser (ESPI) au cours d’une sollicitation de traction uniaxiale. Il a été montré que le modèle mathématique utilisé, croisement de deux bandes rectilignes, décrit bien l’évolution du champ de vitesse de déformation depuis la striction diffuse jusqu'à rupture. Les caractéristiques physiques de la localisation, telles que la largeur des bandes, leur orientation et leur vitesse de déformation maximale ont été identifiées quantitativement. Leur évolution a été suivie et analysée sous plusieurs facteurs d’influence, qui sont à la fois microscopiques, tels que la taille de grains et la structure cristalline, et macroscopiques, comme la géométrie de l’éprouvette et la direction de son prélèvement par rapport à la direction de laminage, et la vitesse de traction. Il a été trouvé que les bandes de localisation rétrécissent au cours de la striction et leur orientation évolue également. Ces évolutions, le mode de striction et le moment de transition entre la striction diffuse et localisée sont influencés différemment par ces facteurs / The evolution of the plastic strain localization field of ductile metals was followed by electronic speckle pattern interferometry (ESPI) during a uniaxial tensile test. It was shown that the mathematical model, a system of two crossing straight bands, describes accurately the evolution of the strain rate field from diffuse necking up to rupture. The physical characteristics of the localization, such as the width of the bands, their orientations and maximum strain rates were identified quantitatively. Their evolutions were followed and analyzed from several influencing factors, which are both microscopic, such as grain size and crystal structure, and macroscopic, like the geometry of the specimen and the direction in which the specimen were cut with respect to the rolling direction, and the pulling speed. It has been found that the bands narrow down during the necking process and their orientations were also changing. These evolutions, the necking mode and the transition between the diffuse and localized necking are influenced differently by these factors