Towards true imaging by wideband speckle interferometry

Bates, R. H. T.; Cady, Fredrick M.

doi:10.1016/0030-4018(80)90261-8

Cited by 127 publications

(35 citation statements)

References 8 publications

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“…We then carried out a precentering and a sorting according to the maximum intensity of the central peak. We then applied the shift-and-add technique (Bates & Cady 1980) to obtain the best possible angular resolution. This method enables to enhance the Strehl ratio by selecting the frames that are the least altered by the atmospheric turbulence.…”

Section: Introductionmentioning

confidence: 99%

Searching for visual companions of close Cepheids

Gallenne

Kervella

Mérand

et al. 2014

A&A

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Aims. High-resolution imaging in several photometric bands can provide color and astrometric information of the wide-orbit component of Cepheid stars. Such measurements are needed to understand the age and evolution of pulsating stars. In addition, binary Cepheids have the potential to provide direct and model-independent distances and masses. Methods. We used the NAOS-CONICA adaptive optics instrument (NACO) in the near-infrared to perform a deep search for wide components around the classical Cepheids, Y Oph, FF Aql, X Sgr, W Sgr, and η Aql, within a field of view of 1.7 × 1.7 (3.4 × 3.4 for η Aql). Results. We were able to reach contrast ∆H = 5-8 mag and ∆K s = 4-7 mag in the radius range r > 0.2 , which enabled us to constrain the presence of wide companions. For Y Oph, FF Aql, X Sgr, W Sgr, and η Aql at r > 0.2 , we ruled out the presence of companions with a spectral type that is earlier than a B7V, A9V, A9V, A1V, and G5V star, respectively. For 0.1 < r < 0.2 , no companions earlier than O9V, B3V, B4V, B2V, and B2V star, respectively, are detected. A component is detected close to η Aql at projected separation ρ = 654.7 ± 0.9 mas and a position angle PA = 92.8 ± 0.1• . We estimated its dereddened apparent magnitude to be m 0 H = 9.34 ± 0.04 and derived a spectral type that ranges between an F1V and an F6V star. Additional photometric and astrometric measurements are necessary to better constrain this star and check its physical association to the η Aql system.

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Section: Introductionmentioning

confidence: 99%

Searching for visual companions of close Cepheids

Gallenne

Kervella

Mérand

et al. 2014

A&A

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“…We do not think that the simplicity of SAA-based imaging is largely spoiled by introducing the deconvolution postprocess. For more faint objects, we can gain a sufficient SNR by broadening the spectral bandwidth in observing the speckle images, which owes to the fact that in SAA imaging the allowable bandwidth of the specklegrams can be taken wider than that in other methods of speckle imaging (Bates & Cady 1980). Such a tolerability with respect to the spectral bandwidth is another advantage of SAA.…”

Section: Discussionmentioning

confidence: 99%

Image Restoration of Io by Shift-and-Add Method and Deconvolution

Kuwamura

Tsumuraya²,

Miura

et al. 2008

PUBL ASTRON SOC PAC

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ABSTRACT. Atmospheric turbulence degrades the image resolution of a ground-based telescope, and a speckle imaging technique can restore the image with high resolution up to the diffraction limit. We have obtained the speckle data of Io (a Jupiter's satellite) using the 2 m telescope in Nishi-Harima Astronomical Observatory. The speckle data are reduced by the shift-and-add method followed by a background-subtraction procedure. The reduced image is then deconvolved by the similarly reduced image of the unresolved binary star HR6168. The comparison with the close-up image taken by the Voyager 2 spacecraft reveals that the restored image shows well-resolved structural features on the surface of Io.

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“…In this last sense, our method is closer to another speckle interferometry technique termed the shift-and-add algorithm. 7 In our demonstration of imaging system, shown in Fig. 1, we placed chicken bone between two slabs of chicken breast.…”

Section: Noninvasive Optical Imaging By Speckle Ensemblementioning

confidence: 99%

Techniques of noninvasive optical tomographic imaging

2006

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Recently invented methods of optical tomographic imaging through scattering and absorbing media are presented. In one method, the three-dimensional structure of an object hidden between two biological tissues is recovered from many noisy speckle pictures obtained on the output of a multi-channeled optical imaging system. Objects are recovered from many speckled images observed by a digital camera through two stereoscopic microlens arrays. Each microlens in each array generates a speckle image of the object buried between the layers. In the computer each image is Fourier transformed jointly with an image of the speckled point-like source captured under the same conditions. A set of the squared magnitudes of the Fourier-transformed pictures is accumulated to form a single average picture. This final picture is again Fourier transformed, resulting in the three-dimensional reconstruction of the hidden object. In the other method, the effect of spatial longitudinal coherence is used for imaging through an absorbing layer with different thickness, or different index of refraction, along the layer. The technique is based on synthesis of multiple peak spatial degree of coherence. This degree of coherence enables us to scan simultaneously different sample points on different altitudes, and thus decreases the acquisition time. The same multi peak degree of coherence is also used for imaging through the absorbing layer. Our entire experiments are performed with a quasi-monochromatic light source. Therefore problems of dispersion and inhomogeneous absorption are avoided.

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Towards true imaging by wideband speckle interferometry

Cited by 127 publications

References 8 publications

Searching for visual companions of close Cepheids

Searching for visual companions of close Cepheids

Image Restoration of Io by Shift-and-Add Method and Deconvolution

Techniques of noninvasive optical tomographic imaging

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