Speckle imaging

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

High Resolution Speckle Methods For Overcoming Image Degradation Caused By The Atmosphere And Telescope Aberrations

Abstract: We discuss various high resolution speckle methods that can overcome image degradation caused by the atmosphere and telescope aberrations. All methods yield diffraction-limited resolution, for example 0.03" for a 3.6m telescope. We show speckle interferometric observations of asteroids, Pluto/ Charon, double stars, and the gravitational-lens triple quasar. True diffraction-limited images can be reconstructed by speckle interferometry if there is a point, source in the isoplanatic neighborhood of the object (holographic speckle interferometry). Speckle masking is a triple-correlation method that yields diffraction-limited images of general astronomical objects. A point source near the object is not required. We describe an application of speckle masking to the central object in the giant HII region NGC 3603. Speckle spectroscopy is a speckle method that yields diffraction-limited objective prism spectra. It is also possible to apply speckle masking to multiple-mirror interferometers or long-baseline interferometers on the ground or in space. True images of very high angular resolution can be obtained by these techniques. Computer simulations are shown for illustration.

The identification of fringe positions in speckle patterns

Abstract: This paper two methods of identifying fringe positions in speckle patterns. The first uses local directional averaging to track fringes, while the second uses standard image processing techniques to connect the patterns into a form where the fringes can be identified.

The Differential Speckle Interferometer

Abstract: We describe a new technique called "Differential Speckle Interferometry" (DSI) which uses simultaneous narrow band images of astronomical objects to study their structure. Simultaneous specklegrams of red supergiant and giant stars taken in the hydrogen lines and in the nearby continuum allow us to reconstruct the image of the extended chromospheres of these stars at resolutions of 100 nanoradians and better. We describe the instrumentation, analysis techniques, and results related to DSI.© (1984) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Simultaneous acquisition of 3D shape and deformation by combination of interferometric and correlation-based laser speckle metrology.

Abstract: A metrology system combining three laser speckle measurement techniques for simultaneous determination of 3D shape and micro- and macroscopic deformations is presented. While microscopic deformations are determined by a combination of Digital Holographic Interferometry (DHI) and Digital Speckle Photography (DSP), macroscopic 3D shape, position and deformation are retrieved by photogrammetry based on digital image correlation of a projected laser speckle pattern. The photogrammetrically obtained data extend the measurement range of the DHI-DSP system and also increase the accuracy of the calculation of the sensitivity vector. Furthermore, a precise assignment of microscopic displacements to the object’s macroscopic shape for enhanced visualization is achieved. The approach allows for fast measurements with a simple setup. Key parameters of the system are optimized, and its precision and measurement range are demonstrated. As application examples, the deformation of a mandible model and the shrinkage of dental impression material are measured.