Gravitational lensing by an extended mass distribution

Understand

We continue our investigation of the optical properties of the solar gravitational lens (SGL).

• We treat the Sun as an extended axisymmetric body and model its gravitational field using zonal harmonics.
• We consider a point source that is positioned at a large but finite distance from the Sun and, using our new angular eikonal method, we established the electro-magnetic (EM) field on the image plane in the focal region behind the SGL and derive the SGL's impulse response in the form of its point-spread function (PSF).
• The expression that we derive describes the extended Sun in all regions of interest, including the regions of strong and weak interference and the region of geometric optics.