"Martin Brown" wrote in message
...
Marc Reinig wrote:

Babcock's proposed (1953) Eidophor used a mirror covered with a film of
oil scanned by an electron beam to change the local slope.

It was never implemented, however.

? Eidophors were invented by Fischer in 1939 and the first one
demonstrated in 1943. There was one still in use in a lecture theatre at
my university in the late 1970's.

There is a picture of the prototype online at:
http://www.cinephoto.co.uk/eidophor_1.htm

Regards,
Martin Brown

Yes, Eidophors existed prior to Babcocks proposal, as did lenses, mirrors,
knife edges and slits. But I believe Babcock was the first with a serious
proposal to use the Eidophor, et al to correct for atmospheric distortion
for observations.

Marc Reinig
UCO Lick Observatory
Laboratory for Adaptive Optics