Topic
Speckle imaging
About: Speckle imaging is a research topic. Over the lifetime, 3730 publications have been published within this topic receiving 62354 citations.
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TL;DR: Analytical models for the relevant transfer functions of an adaptive optics systems including the effect of an arbitrary correction as well as anisoplanatism are presented.
Abstract: Adaptive optics supported solar speckle imaging requires the calibration of the
source's Fourier amplitudes with the transfer function of atmosphere and optics. We
present analytical models for the relevant transfer functions of an adaptive optics
systems. The models include the effect of an arbitrary correction as well as
anisoplanatism. The proposed models have been compared with observational data using
measurements of α-Orionis and of the solar surface delivering both a direct and
indirect method (using the spectral ratio technique) for validation. We find that
measurements and model agree to a satisfactory degree.
60 citations
60 citations
TL;DR: Although the aim of the research is to develop techniques useful to the engineer, developments are also being made in the use of speckle patterns for information processing, where the pattern is employed as an optical carrier.
Abstract: Publisher Summary This chapter discusses the nature of the speckle pattern and defines some of its basic characteristics. The speckle effect in optics is the generation of a random intensity pattern formed when coherent light is scattered by a rough surface or is diffused by a medium containing scattering centers. The chapter concentrates on the instrumental aspects of speckle interferometry and their applications rather than a detailed theoretical treatment. It is seen that a considerable degree of ingenuity has had to be employed to overcome the inherent difficulties that occur when interference takes place among randomly distributed phase fields rather than among smoothly varying ones. Although the aim of the research is to develop techniques useful to the engineer, developments are also being made in the use of speckle patterns for information processing, where the pattern is employed as an optical carrier.
60 citations
TL;DR: In this paper, a laser speckle shearing interferometric technique is used for measuring the temperature profile inside a gaseous flame and the experimental results are compared with the values obtained by a thermocouple and also by speckel photography.
Abstract: A laser speckle shearing interferometric technique is used for measuring the temperature profile inside a gaseous flame. The experimental results are compared with the values obtained by a thermocouple and also by speckle photography. Good agreement is seen among the temperatures measured by speckle shearing interferometry, speckle photography, and the thermocouple. Speckle shearing interferometry is easier to implement than speckle photography. This is because in speckle shearing interferometry the accurate positions of the fringes can be known without point-by-point analysis and correction for the halo effect.
59 citations
TL;DR: The possibilities and limitations for real time shearing fringe observation using the electronic speckle pattern interferometry technique are explored, and some preliminary results are shown.
Abstract: Since shearing interferometry, also called shearography, does not depict fringes caused by object tilt, it is a tool well suited for either nondestructive testing of objects under load or for quantitative evaluation of flexural strains. In traditional shearing interferometry, observation of fringes requires optical processing of double-exposed interferograms. Hence the technique is not in real time. This paper explores the possibilities and limitations for real time shearing fringe observation using the electronic speckle pattern interferometry technique. Prospects for quantitative determination of local tilt and flexural strain using the phase shifting technique are commented on, and some preliminary results are shown.
59 citations