Television camera with optical storage and scanning.

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Television camera with optical storage and scanning.

Postby Stephen » Thu Feb 08, 2007 4:16 am

A well known problem with television cameras of the optical scanning type is the small amount of light available to the camera pickup. The intermediate film system used in the 1930's provided a clumsy form of optical storage that overcame this problem and at the time it was the only way to provide high definition optical scanning for outdoor use due to small scanning aperture size.

Another way to provide optical storage for television cameras of the optical scanning variety is with an image intensifier tube. The image intensifier tube provides a relatively bright phosphor display of a relatively dim image focussed on its photocathode. The optical scanning element may then scan the bright image intensified phosphor display of the image intensifier tube.
Stephen
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Photo Multipiers

Postby Klaas Robers » Fri Feb 09, 2007 5:08 am

The problem of the limited amount of light is less a problem than you might think. A photo multiplier is extremely sensitive. This tube behind a Nipkow disc wil give you good video even at dim lighting conditions. The advantage is that the produced noise is proportional to the output signal, in absolute darkness no signal, but also no noise.
Yes of course, you need 900 to 1000 volts to operate them, but that is more a challenge than a disadvantage.
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