REM%MIT-MC@sri-unix.UUCP (06/11/84)
From: Robert Elton Maas <REM @ MIT-MC> Aha, indeed putting the occluding disk at the prime focus of the solar telescope instead of "in front" solves the parallax problem, and if everything in the light path up to the occluding disk, except the primary mirror, is painted flat black and if all dust is carefully removed from the mirror and everything else along that path, the internal reflection problem should be minimized. (I presume it'd be impossible to eliminate internal reflections in a lens, thus I say mirror instead of lens, but I may be mistaken.) With a long-focal-length primary mirror, so the primary image will be relatively large, diffraction around the edges of the occluding disk should also be minimized. Thanks for the info/correction. (But if the technique is so workable, why are natural eclipses so important even now? Why don't we see wonderful artificially-occluded solar images from space every flight of STS, making natural eclipses moot? My guess, funding is short, STS flights are all booked, ...)