It’s interesting how it appears to have a finite DOF despite being at optical infinity. Of course, it wasn’t imaged optically.
I don’t see any mention of DoF in that linked article. The do mention a resolution of 5m (The theoretical resolution for the frequency they use would be on the order of cm)
That’s why I said “appears”, just from a visual viewpoint. It looks as if the near edge is sharper than the far.