Digicon
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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] One of digicon's advantages is its very large dynamic range and it results from the short response and decay times of silicon diodes.[2]
Development
In 1971, E.A. Beaver and Carl McIlwain successfully demonstrated a way in which silicon diodes can be used in digital tube by placing a silicon diode array that contained 38 elements in the same chamber as a photocathode.[2] The design and manufacture of the Digicon tube is attributed to John Choisser of the Electronic Vision Corporation.[3]
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.[citation needed] For instance, there were two pulse-counting Digicon detectors in the Goddard High Resolution Spectrograph installed on the Hubble Space Telescope from 1990–1997, used to record ultraviolet spectra.[4] Digicon is also used in digital imaging such as the case of a scanning gage using Digicon imaging tube, which generates a two-dimensional view with high spatial resolution when an object is scanned past the Digicon.[5]
References
- ^ "The Digicon Detectors". www.stsci.edu.
- ^ a b Meaburn, J. (2012). Detection and Spectrometry of Faint Light. Dordrecht: Springer Science+Business Media, B.V. p. 36. ISBN 9789027711984.
- ^ Morgan, B.L.; Airey, R.W.; McMullan, D. (1976). Advances in Electronics and Electron Physics. London: Academic Press. p. 761. ISBN 0120145545.
- ^ Böhme, S.; Esser, U.; Hefele, H.; Heinrich, I.; Hofmann, W.; Krahn, D.; Matas, V. R.; Schmadel, L. D.; Zech, G. (2013). Astronomy and Astrophysics Abstracts: Volume 42 Literature 1986. Springer Science & Business Media. p. 186. ISBN 978-3-662-12382-9.
- ^ Berger, Harold (1976). Practical Applications of Neutron Radiography and Gaging. Philadelphia, PA: ASTM International. p. 72. ISBN 0803105355.
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