Imaging with a gravitational lens: the geometric view

TL;DR

This paper analyzes the imaging capabilities of a monopole gravitational lens, like the Solar Gravitational Lens, using geometric optics to compute light amplification and derive a practical point-spread function.

Contribution

It provides a geometric optics framework for gravitational lens imaging, aligning with wave theory, and offers a usable point-spread function for simulations.

Findings

Light amplification computed for a gravitational lens with a circular aperture.

Derived an averaged point-spread function consistent with wave theory.

Validated the geometric optics approach for practical imaging calculations.

Abstract

We investigate imaging point sources with a monopole gravitational lens, such as the Solar Gravitational Lens in the geometric optics limit. We compute the light amplification of the lens used in conjunction with a telescope featuring a circular aperture that is placed in the focal region of the lens, compared to the amount of light collected by the same telescope unaided by a gravitational lens. We recover an averaged point-spread function that is in robust agreement with a wave-theoretical description of the lens, and can be used in practical calculations or simulations.