Speckle imaging

About: Speckle imaging is a research topic. Over the lifetime, 3730 publications have been published within this topic receiving 62354 citations.

Laser Speckle and Applications in Optics

Abstract: M Francon (translated H H Arsenault) 1979 New York: Academic xii + 161 pp price $16 The random interference pattern produced when coherent light strikes a rough surface is called speckle; in the last 10–15 years many studies of the statistics of these patterns have appeared. The main applications seem to be in surface roughness estimation, in astronomy for overcoming atmospheric turbulence by speckle interferometry, and in the measurement of surface displacements and strains.

Laser speckle imaging of atherosclerotic plaques through optical fiber bundles.

Abstract: Laser speckle imaging (LSI), a new technique that measures an index of plaque viscoelasticity, has been investigated recently to characterize atherosclerotic plaques. These prior studies demonstrated the diagnostic potential of LSI for detecting high-risk plaques and were conducted ex vivo. To conduct intracoronary LSI in vivo, the laser speckle pattern must be transmitted from the coronary wall to the image detector in the presence of cardiac motion. Small-diameter, flexible optical fiber bundles, similar to those used in coronary angioscopy, may be incorporated into an intravascular catheter for this purpose. A key challenge is that laser speckle is influenced by inter-fiber leakage of light, which may be exacerbated during bundle motion. In this study, we tested the capability of optical fiber bundles to transmit laser speckle patterns obtained from atherosclerotic plaques and evaluated the influence of motion on the diagnostic accuracy of fiber bundle-based LSI. Time-varying helium-neon laser speckle images of aortic plaques were obtained while cyclically moving the flexible length of the bundle to mimic coronary motion. Our results show that leached fiber bundles may reliably transmit laser speckle images in the presence of cardiac motion, providing a viable option to conduct intracoronary LSI.

Dealing With Speckle Effects in Self-Mixing Interferometry Measurements

Abstract: An analysis of speckle effects and the techniques to overcome them in self-mixing interferometry signals is presented. We characterize the effect of surface roughness and laser spot size on the speckle modulation of the signal, and then propose two simple experimental approaches to overcome the amplitude fading induced by the speckle effect. Unlike the techniques proposed until now, our first approach uses an adaptive optical element in the form of a voltage-programmable liquid lens, which adaptively changes its focal length to modify the speckle pattern. Our second approach combines two laser signals which present different performance parameters. By using any of these simple methods, the introduction of inaccuracies in the measurement process due to speckle is avoided.

Speckle Reduction by Spatial-Domain Mask in Digital Holography

Abstract: The image quality improvement method using a spatial-domain mask is proposed. In the proposed method, a single hologram is required for speckle reduction. The speckle noise of the reconstructed image is suppressed by averaging different speckle patterns. The different speckle patterns are generated by shifting the rectangular aperture in the hologram plane. The experiment results including a modulation transfer function are presented to confirm the performance of the proposed method.