The paper A mission architecture to reach and operate at the focal region of the solar gravitational lens proposes a Solar Gravitational Lens (SGL) Telescope at ~500 AU that would use the gravitational lens created by the Sun to view distant objects with much higher magnification than has previously been possible.
Einstein in 1915 predicted that the Sun's gravitational field would deflect light by Θ=1.75, which confirmed by the Eddington experiment in 1919.
In 1936 Einstein discussed the possiblity of a ring lens being observable from a suitable location, though he considered it practically impossible that we would find any. Actual gravitational lenses have since been observed.
The SGLT would be positioned to take advantage of the Sun's gravitational ring lens. This calculation checks that tangent of the Sun's deflection is nearly equal to the expected solarRadius / 500 AU for the SGLT.
This graphic is a helpful visualization for the geometry for a
complete and
powerful Einstein
Ring system as observed from Earth. The SGLT geometry would
be similar, but with a much longer DL to accomodate the
relatively weak deflection of the Sun.