Restoration of light correlation function from the data of delayed photocounts in intensity interferometry

Kurashov, Vitalij N.; Kurashov, Andrey V.; Piskarev, Vladislav L.

doi:10.1117/12.295714

Cited by 3 publications

(3 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…-Implementation of an eigenfunction method to the problem of correlation function restoration from the photocurrent data 25 .…”

Section: )mentioning

confidence: 99%

Micro-arcsec imaging from the ground with intensity interferometers

Ribak

2006

Advances in Stellar Interferometry

View full text Add to dashboard Cite

Stellar amplitude interferometry is limited by the need to have optical distances known to a fraction of the wavelength. We suggest reviving intensity interferometry, which requires far less accurate hardware (~1cm mechanical precision) at the cost of more limited sensitivity. We present an algorithm that uses the very high redundancy of a uniform linear array to increase the sensitivity of the instrument by more than a hundredfold. An array of a hundred ~100m diameter elements can achieve a limiting magnitude of m b =14.4. Off-line processing of the data will enable such a ground-based facility to transform a two-dimensional field of point-like sources to a three-dimensional distribution of micro-arcsec resolved systems, each imaged in several optical bands. Each system will also have its high resolution residual timing, high quality (inside each band) spectra and light curve, emergent flux, effective temperature, polarization effects and perhaps some thermodynamic properties, all directly measured in a single observation run of such a dedicated facility. Coronagraphy, selectively suppressing large scale structures of the sources, can also be achieved by specific aperture shapes. We conclude that after three decades of abandonment optical intensity interferometry deserves another review, also as a ground-based alternative to the science goals of space interferometers.

show abstract

“…-Implementation of an eigenfunction method to the problem of correlation function restoration from the photocurrent data 25 .…”

Section: )mentioning

confidence: 99%

Micro-arcsec imaging from the ground with intensity interferometers

Ribak

2006

Advances in Stellar Interferometry

View full text Add to dashboard Cite

show abstract

“…We also refer to other proposed algorithms related to intensity interferometry improvement: -Improving the contrast between different parts of the image, and enlarging it without any limitation and, in spite of this enlargement, without any distortions of objects borders caused by discreteness of initial image [18]. -Implementation of an eigenfunction method to the problem of correlation function restoration from the photocurrent data [19].…”

Section: Off-line Multi-detector Intensity Interferometersmentioning

confidence: 99%

Offline, multidetector intensity interferometers - II. Implications and applications

Ribak¹

2006

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Intensity interferometry removes the stringent requirements on mechanical precision and atmospheric corrections that plague all amplitude interferometry techniques at the cost of severely limited sensitivity. A new idea we recently introduced, very high redundancy, alleviates this problem. It enables the relatively simple construction (~1cm mechanical precision) of a ground-based astronomical facility able to transform a two-dimensional field of point-like sources to a three-dimensional distribution of micro-arcsec resolved systems, each imaged in several optical bands. Each system will also have its high resolution residual timing, high quality (inside each band) spectra and light curve, emergent flux, effective temperature, polarization effects and perhaps some thermodynamic properties, all directly measured. All the above attributes can be measured in a single observation run of such a dedicated facility. We conclude that after three decades of abandonment optical intensity interferometry deserves another review, also as a ground-based alternative to the science goals of space interferometers.Subject Heading: instrumentation: interferometers -instrumentation: high angular resolution -techniques: interferometric 1. INTRODUCTION Amplitude interferometry is today's mainstream technique for high angular resolution astronomy, mainly in the infrared regime. In principle, amplitude interferometers combine the electromagnetic waves from two or more separate locations to produce a high-resolution brightness distribution, or image, of the source. Intensity interferometry, on the other hand, combines the intensities of the electromagnetic wave via the correlation of the electrical currents generated by the detectors of the already-detected intensities. For astronomical purposes, the main advantage of intensity interferometry is its mechanical robustness: the required mechanical accuracy depends on the electrical bandwidth of the detectors, and not on the wavelength of the light. This opto-mechanical robustness also means that the atmosphere does not influence the performance of the instrument. The main disadvantages of intensity interferometry are its very low intrinsic sensitivity and the fact that the classical, two-detector intensity interferometer cannot reconstruct the phase of the complex degree of coherence, and thus can't be used to produce true images [1].

show abstract

“…The method was tested on several different protein structures with excellent results [1,2] The programs are available on http://www.img.cas.cz/hiphop/.…”

mentioning

confidence: 99%

Deconvolution of X-ray diffraction profile by using the regularization technique

Piskarov¹,

Wagner²,

Hempelmann³

2005

Acta Cryst Sect A

View full text Add to dashboard Cite

Refining an initial protein model to its final structure is usually composed of rounds of refinement performed by programs such as CNS and REFMAC, and manual model modification that includes linking and extending fragments, and fitting the ill matched residues of model by using the computer graphics program such as O. The manual model modification requires expertise of crystallography to recognize structural conformation based on electron density, and it is a time consuming process.For the purpose of reducing the time and manual intervention of refinement, we developed a software named LAFIRE (Localcorrelation-coefficient-based Automatic FItting for REfinement) to automate the whole refinement process. Four function modules are designed: building the missing parts in the current model, fitting the model to the electron density map, monitor program and an interface for combining the first two modules and the refinement programs CNS and REFMAC5.The LAFIRE is already in the state that builds the whole model from fragments by iterative approach, and performs structural refinement process without manual intervention in a few hours or days.LAFIRE A novel refinement method called HipHop refinement is described. Although HipHop refinement seems to be similar to simulated annealing refinement it is based on a different philosophynamely that it is in principle impossible to determine a complete structure at a limited resolution. Thus, the limited resolution and the inaccuracy of the underlying X-ray data cause not only errors in the refined structural parameters but principal structural errors in the single model, which is usually used to explain the data.HipHop refinement is performed in several steps. In the first step, a proper number of pseudo waters corresponding to maxima in the difference Fourier map is added to the model (HIP step, H 2 O input). In the next step, the model is refined and waters not fulfilling density, shape or position criteria are removed from the model (steps HOP, H 2 O output). The process is in fact jumping between local minimaHipHop. During HipHop cycles not only the water arrangement but also side/main chain orientation is changed. The best presentation of HipHop refinement is a multi conformer PDB file.The method was tested on several different protein structures with excellent results [1,2] The programs are available on http://www.img.cas.cz/hiphop/.[1] Ondrá ek J., Weiss M.S., Mesters J.R., Acta Cryst., manuscript in preparation.[2] Ondrá ek J., Weiss M.S., Brynda J., Fiala J., Jursík F., ezá ová P., Jenner L.B., Sedlá ek J., Acta Crys., submitted for publication.Keywords The deconvolution of the instrumental function in X-Ray diffraction profile analysis is a basic step in order to obtain reliable results on the microstructure (crystallite size, lattice microstrain, etc.) and is a typical example of ill-posed inverse problems. The implementation of an eigen function method with different regularization techniques is investigated and a simple regularization algorithm is proposed.A simulat...

show abstract

Restoration of light correlation function from the data of delayed photocounts in intensity interferometry

Cited by 3 publications

References 1 publication

Micro-arcsec imaging from the ground with intensity interferometers

Micro-arcsec imaging from the ground with intensity interferometers

Offline, multidetector intensity interferometers - II. Implications and applications

Deconvolution of X-ray diffraction profile by using the regularization technique

Contact Info

Product

Resources

About