Coded masks in X- and γ-ray astronomy: the problem of the signal-to-noise ratio evaluation

Caroli, E.; Butler, R. C.; Cocco, G. Di; Maggioli, P.; Natalucci, L.; Spizzichino, A.

doi:10.1007/bf02573805

Cited by 10 publications

(14 citation statements)

References 16 publications

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“…At the same time we will consider the general case where it is not necessarily true that S B f,t , breaking 3. This case, and the associated issue of the optimum open fraction of the mask when S < B f,t , have been discussed in the literature [10,13,28,[48][49][50][51]], but we here try to provide a unified approach and to correct some errors that have arisen.…”

Section: Assumptions Frequently Madementioning

confidence: 99%

Sensitivity of coded mask telescopes

Skinner

2008

Appl. Opt.

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Simple formulae are often used to estimate the sensitivity of coded mask X-ray or gamma-ray telescopes, but these are strictly only applicable if a number of basic assumptions are met. Complications arise, for example, if a grid structure is used to support the mask elements, if the detector spatial resolution is not good enough to completely resolve all the detail in the shadow of the mask or if any of a number of other simplifying conditions are not fulfilled. We derive more general expressions for the Poisson-noise-limited sensitivity of astronomical telescopes using the coded mask technique, noting explicitly in what circumstances they are applicable. The emphasis is on using nomenclature and techniques that result in simple and revealing results. Where no convenient expression is available a procedure is given which allows the calculation of the sensitivity. We consider certain aspects of the optimization of the design of a coded mask telescope and show that when the detector spatial resolution and the mask to detector separation are fixed, the best source location accuracy is obtained when the mask elements are equal in size to the detector pixels.

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Section: Assumptions Frequently Madementioning

confidence: 99%

Sensitivity of coded mask telescopes

Skinner

2008

Appl. Opt.

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“…We call the coefficient terms related to neighboring sources "interference coefficients" in this paper. Caroli et al used a similar convolution method using different notations than those in Fenimore's studies [5].…”

Section: Introductionmentioning

confidence: 98%

“…If we restrict the analyses of the SNR to the far-field coded aperture imaging system, we may use convolutional reconstruction methods. A direct inversion method was introduced in Caroli et al's studies [1,5].…”

Section: Introductionmentioning

confidence: 98%

“…We first review an unbiased mean estimator in Fenimore's study [2] and a biased mean estimator in Caroli et al's work [5] in Section 2. We present general conditions for designing an unbiased estimator for a coded aperture imaging system based on a random mask in Section 3.…”

Section: Introductionmentioning

confidence: 99%

“…The quantitative analyses of the SNR of particular coded aperture imaging systems with URAs or pseudo noise arrays were introduced by Fenimore [2] and Caroli et al [5]. Fenimore and Gottesman evaluated the SNRs point-by-point by using the balanced correlation method [6].…”

Section: Introductionmentioning

confidence: 99%

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Unbiased and biased estimators in coded aperture imaging for far field standoff detection at low count rates

et al. 2013

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In general, the reconstructed image in coded aperture imaging is affected by the source configuration. Fenimore's balanced convolution method in conjunction with the uniformly redundant array can remove the interference due to the source configuration. As an extension of Fenimore's balanced convolution method, we present general conditions for designing an unbiased mean estimator for a far-field coded aperture imaging system with a random binary mask. As part of the general conditions, we propose decoding arrays whose elements are variable with respect to source directions. We also show that the unbiased mean estimator from Fenimore's balanced convolution method is a special case of the general conditions. We also present a practical example of designing restoring arrays for a coded aperture system with a random mask.

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