Speckle imaging

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

Stellar speckle image reconstruction by the shift-and-add method

Abstract: Naoshi Baba, Syuzo Isobe, Youji Norimoto, and Motokazu Noguchi Naoshi Baba is with Hokkaido University, Department of Applied Physics, Faculty of Engineering, Sapporo 060, Japan; the other authors are with University of Tokyo, Tokyo Astronomical Observatory, Mitaka 181, Japan. Received 27 November 1984. 0003-6935/85/101403-03$02.00/0. © 1985 Optical Society of America. The shift-and-add method proposed by Bates and Cady is a simple reconstruction technique for true imaging of stellar objects. This method can be regarded as an extension of the technique invented by Lynds et al. , which, however, needs complicated procedures. Lynds et al. applied their technique to reconstruct α Ori. There are some variations of the shiftand-add method. Bagnuolo used his version of it to in­ vestigate α Aur. We applied the simple shift-and-add method to reconstruct a binary star, α Com, which was ob­ served with wide bandwidth light. The simple shift-and-add method is stated as follows: the brightest point in each speckle image is shifted to the center of image space, and the translated image is added to all other speckle images that have been similarly processed. The theoretical analysis of this method has been described by Bagnuolo and by Hunt et al. Speckle interferometric observations were carried out at the Okayama Astrophysical Observatory on the night of 17 Feb. 1984: α Com was observed with our speckle camera combined with the ƒ/13.0 Cassegrain focus of the 91-cm tele­ scope. The speckle camera we developed contains a Philips XX1500 image intensifier and a l0× microscope objective. Speckle data were recorded on Tri-X film. Bates and Caddy showed in their simulation experiments that the shift-and-add method is applicable to white light speckle images. We examined the performance of this method for wideband speckle images, and we recorded speckle images without a filter, namely, the effecive bandwidth of the recording system was defined by the spectral response of the

Contouring by laser speckle.

Abstract: A technique is presented to determine surface contours of 3-D objects by laser speckle interferometry A double exposure specklegram is recorded by giving the object a small tilt between exposures Surface contours are obtained by Fourier filtering of the specklegram

Algorithms for simulation of speckle (laser and otherwise)

Abstract: The speckle phenomenon is observed in any coherent imaging modality such as synthetic aperture radar, optical coherence tomography, ultrasound, or any number of measurement schemes involving laser illumination. Quantitative interpretation of the data from such measurement schemes (whether imaging or non-imaging) often hinges on accurate knowledge of the statistical behavior of the speckle phenomenon. To complement experimental measurements, researchers often turn to computer simulation of the phenomenon of interest. Over the years we have developed a variety of algorithms for simulating objective and subjective speckle for static and dynamic object fields. In this paper we detail the implementation of these algorithms and illustrate their use in a range of applications that include Electronic Speckle Pattern Interferometry (ESPI), Laser Speckle Imaging (LSI), Optical Coherence Tomography (OCT), etc.

Displacement Measurement by Image-processed Speckle Patterns

Abstract: The use of a commercial image-processing system in digital speckle-pattern interferometry is demonstrated. The possibilities of electronic-noise suppression and speckle-noise smoothing are discussed. Synthetic speckle patterns have been created and are shown to be useful in software development. Fringe skeletons have been extracted automatically from both synthetic and experimental correlation fringes giving accurate quantitative results.

Space object imaging through the turbulent atmosphere

Abstract: For telescopes operating at optical wavelengths, the turbulence of the atmosphere limits the resolution of space objects to about one second of arc, although the diffraction limit of the largest telescopes is many times as fine. We discuss an image processing technique that uses interferometer data (the modulus of the Fourier transform) to reconstruct diffraction limited images. Data from a stellar speckle interferometer or from an amplitude interferometer can be used. The processing technique is an iterative method that finds a real, non-negative object that agrees with the Fourier modulus data. For complicated two-dimensional objects, the solutions found by this technique are surprisingly unique. New results are shown for simulated speckle interferometer data having realistic noise present.© (1978) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.