Quantum-limited near-infrared vidicon camera system

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Abstract
A television camera system utilizing an RCA C33020H, S‐1 photocathode, electrostatic intensifier tube fiber optically coupled to an RCA C21145 SIT vidicon has been constructed and laboratory tested. The 40‐mm‐diam I‐SIT tube assembly is cooled with dry ice to −40 °C, and the commercial Cohu video preamplifier is maintained at +15 °C with a dc heater. The camera integration unit incorporates a target preparation cycle to linearize the SIT tube target response at low light levels. The camera head operates with a four‐position filter wheel controlled by an integration logic unit. Hughes model 639 scan converters or an Ampex disk unit allow real‐time comparison of data frames taken with different filters. Data frames are recorded on video tape for later analysis. The camera obtains ∼300 TV‐line resolution frames in 1 min integration with highlight irradiance 1.4×10−13 W/cm2 at λ=10 830 Å. Signal‐to‐noise ratio is limited by the shot noise from the S‐1 intensifier photocathode in laboratory tests and by the sky background in astronomical or geophysical application. Astronomical observations show that the camera successfully detects the CIT infrared sources and easily images the Orion nebula in He I λ=10 830 Å light.

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