Digicon

A digicon detector is a spatially resolved light detector using the photoelectric effect directly. It uses magnetic and electric fields operating in a vacuum to focus the electrons released from a photocathode by incoming light onto a collection of silicon diodes. It is a photon-counting instrument, so most useful for weak sources.^[1]

Digicon detectors were used on the original instruments for the Hubble Space Telescope, but are very rarely used in new designs, where CMOS active-pixel detectors can achieve the same performance without the need for large electric fields or complicated vacuum assemblies.

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