Fundamental Limit for One versus Two Point Sources Detection using Direct Imaging

Fuente: arXiv
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Main Authors: Darekar, Parth Hemant, Jha, Amit Kumar, Grace, Michael R., Sajjad, Aqil, Guha, Saikat
Format: Preprint
Published: 2026
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author Darekar, Parth Hemant
Jha, Amit Kumar
Grace, Michael R.
Sajjad, Aqil
Guha, Saikat
author_facet Darekar, Parth Hemant
Jha, Amit Kumar
Grace, Michael R.
Sajjad, Aqil
Guha, Saikat
contents We consider the task of distinguishing between a single weak incoherent optical point source and two weak incoherent optical point sources located symmetrically about the first source. $θ$ is the separation between the two point sources scaled to the Point Spread Function (PSF) width in the image plane. Using an ideal focal plane array of intensity detectors (ideal direct imaging), we quantify the performance using the Bhattacharyya distance and find the scaling of its leading order term in terms of $θ$ in the sub-Rayleigh regime. A suite of previous analyses of this problem lacked a comprehensive analysis for when the amplitude spread function (ASF) of the imaging system has zeros and reported a scaling that we find to be incorrect. We complete this analysis by explicitly calculating the leading order term of the Bhattacharyya distance for ideal direct imaging with any ASF, for small $θ$ and show the difference in scaling based on the presence or absence of zeros in the ASF. This is similar to the ASF dependent performance in the task of estimating the separation between the two point sources and the task of detecting a change to an object. We then apply our results to the specific example of a Gaussian and a Sinc ASF and show good agreement with numerical calculations. Our results allow the accurate comparison of other measurement schemes with ideal direct imaging, and to the quantum limit.
format Preprint
id arxiv_https___arxiv_org_abs_2606_00968
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Fundamental Limit for One versus Two Point Sources Detection using Direct Imaging
Darekar, Parth Hemant
Jha, Amit Kumar
Grace, Michael R.
Sajjad, Aqil
Guha, Saikat
Optics
Quantum Physics
We consider the task of distinguishing between a single weak incoherent optical point source and two weak incoherent optical point sources located symmetrically about the first source. $θ$ is the separation between the two point sources scaled to the Point Spread Function (PSF) width in the image plane. Using an ideal focal plane array of intensity detectors (ideal direct imaging), we quantify the performance using the Bhattacharyya distance and find the scaling of its leading order term in terms of $θ$ in the sub-Rayleigh regime. A suite of previous analyses of this problem lacked a comprehensive analysis for when the amplitude spread function (ASF) of the imaging system has zeros and reported a scaling that we find to be incorrect. We complete this analysis by explicitly calculating the leading order term of the Bhattacharyya distance for ideal direct imaging with any ASF, for small $θ$ and show the difference in scaling based on the presence or absence of zeros in the ASF. This is similar to the ASF dependent performance in the task of estimating the separation between the two point sources and the task of detecting a change to an object. We then apply our results to the specific example of a Gaussian and a Sinc ASF and show good agreement with numerical calculations. Our results allow the accurate comparison of other measurement schemes with ideal direct imaging, and to the quantum limit.
title Fundamental Limit for One versus Two Point Sources Detection using Direct Imaging
topic Optics
Quantum Physics
url https://arxiv.org/abs/2606.00968