🚀 go-pugleaf

In article <1993Jan9.000917.22206@qualcomm.com> karn@servo.qualcomm.com (Phil Karn) writes:

   In article <9301081644.AA19208@TIS.COM> mjr@TIS.COM writes:
   >	Those pictures were from a KH-11. KH-11's are presumably
   >quite obsolete. We're talking a matter of years since those pictures
   >were published. If you extrapolate a little bit, based on the kinds
   >of advances in commercial electronic imaging that we've been seeing,
   >it's quite possible that far, far higher resolution pictures are
   >possible.

   You forget about the diffraction limit.  What I found so interesting
   about those pictures was that their resolution (30cm) was just about
   exactly what I'd expect for an objective mirror just small enough to
   fit in the payload shroud of a Titan 3C, operating at visible light
   wavelengths from minimum orbital altitude.  I.e., the KH-11 is already
   operating damn close to the theoretical limits. It's simply not
   possible to do better without getting closer and/or using a larger
   mirror. The laws of physics are the same for classified projects as
   they are for the rest of us.

Actually, *if* your data are good enough (that is, if the signal to
noise ratio is large enough) and *if* you can model the blurring
function well enough, you can do arbitrarily better than the
diffraction limit.  I agree with the statement about the laws of
physics though 8-)

Take a look at some of the papers on the Maximum Entropy Method for
some nice examples.  For instance, some very sparse data (and fairly
noisy -- the data were all smaller than 200 counts if memory is
correct) from an X-ray telescope was deconvolved to show the double
nature of the source.  The processed image was far better than the
original.  Sorry I can't post references just now -- my re-prints are
at home.


Paul
--
Paul Leyland <pcl@oxford.ac.uk>          | Hanging on in quiet desperation is
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