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Proceedings Paper

Photon-counting image tube for space- and ground-based applications
Author(s): Jonathan S. Lapington; Lieuwe B. Boskma; Joost Adema
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Paper Abstract

We describe an image intensifier tube of flexible design, capable of being used for a number of different ground and space-based applications. The tube was originally designed to meet a requirement for an optical photon-counting detector sensitive between 150 and 650 nm with a spatial resolution of less than 20 micrometers . Other performance criteria aimed for were a peak quantum efficiency of greater than 20% and a 200 kHz maximum count rate. The tube has a 25 mm diameter image format which is nominally 2D, though 1D and non-Cartesian imaging formats could be accommodated. Photon detection is via a semitransparent photocathode coated on the detector input window. Liberated photoelectrons are proximity focused on to a microchannel plate (MCP) stack which provides electron gain with a saturated pulse height distribution for photon counting. Imaging is accomplished with conductive charge division readout. The detector geometry is easily modified to accommodate different types of this generic readout type. The imaging electronics consist of several parallel charge measurement channels, the number depending on the readout type. A decoding algorithm provides an x,y photon event coordinate. The detector was manufactured by DEP bv, Holland. The original design utilized an S20 photocathode on a magnesium fluoride or fused silica window but recently detectors have been made with calcium fluoride windows and caesium telluride photocathodes. All detector variants built thus far use a stack of three MCPs in a Z configuration producing an electron gain of between 106 and 2 X 107 depending on MCP conditioning. We present images and performance data from the two types of detector so far built; the original optical intensifier design with a SPAN six electrode image readout, and a variant with a UV photocathode and wedge and strip anode readout. We discuss the problems encountered during the tube development and the solutions arrived at for each type of device.

Paper Details

Date Published: 1 June 1994
PDF: 10 pages
Proc. SPIE 2198, Instrumentation in Astronomy VIII, (1 June 1994);
Show Author Affiliations
Jonathan S. Lapington, Mullard Space Science Lab. (United States)
Lieuwe B. Boskma, DEP/Scientific (Holland) (Netherlands)
Joost Adema, DEP/Scientific (Holland) (United States)

Published in SPIE Proceedings Vol. 2198:
Instrumentation in Astronomy VIII
David L. Crawford; Eric R. Craine, Editor(s)

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