A Diffractive Optics Approach to Achieving the Objectives of the "Black Hole Mission" in the "Beyond Einstein" Program
Gerry Skinner
CESR
skinner@cesr.fr
Additional authors: P. Gorenstein
Diffractive optics (Fresnel lenses and their variants) offer a novel way of achieving the ~micro arc second resolution necessary to 'image' a black hole. The optical system can be surprisingly simple and yet have very high collecting area. Diffraction limited filled-aperture optics ~10 m diameter could be made that would operate at, say, ~6 keV and that would have the 'modest' angular resolutions of ~5 micro arc seconds necessary to resolve Sgr A* and the nucleus of M87. For higher resolution, shorter wavelengths could be used and/or multi-element un-filled aperture interferometric systems using the same principle could be employed. Demands on the relative spacecraft positioning and on target finding are as stringent as for other approaches, but requirements both on the manufacturing of the optical components and on their alignment are surprisingly relaxed and easily achieved.
