<Since the screen is in fact being scanned by the electron beam in the
<monitor, the light that passes through the transparency and to the
<photodetector depends on the darkness of a spot on said transparency
<corresponding to where the electron beam is. As does the output of the
<photodetector. Digitize that, synchronised to the scanning, and you have
<a way to scan images.
Flying spot scanner. Go back about 25-30 years and you could get one for
test patterns for TV service, B&K was one vendor here in the us. The
patterns were 35MM slides if memory serves. The box was a small CRT that
was scanned at fixed bright intensity, a slide holder, lens and a phototube
to translate the light to analog image stream. The same scheme would work
from a reflected image. Using modern technology if you scanned the field
to be viewed with a laser while viewing that with a photodiode with a lens
focused to the resulting output could then be synched and broadcast or
digitized. FYI this is the basic barcode scanner.
The site is still a gag!
Allison
Received on Sat Aug 14 1999 - 22:57:20 BST