(33k JPEG) The diode array is the heart of the Digicon
detector, developed at UCSD. Here, electrons created from the incoming
light are converted into an electrical signal which can be counted and
ultimately relayed to Earth as science data, generally in the form of a
spectrum. There are 512 diodes in the central line seen here. Each is
40 microns wide by 200 microns high. Gold threads connect the diodes
to the pattern of leads which feed through the ceramic substrates. The
diode array, shown enlarged here, is 1 inch in length.
(19k JPEG) The Digicon tube converts incoming light into
useful signals. This side view shows the stacked ceramic ring
structure and the accelerator dynode rings. More than 20,000 volts,
suitably divided among the dynodes by resistors, accelerates the
electrons freed from the photocathode (left) by the photoelectric
effect.
(35k JPEG) Here the Digicon has been partially built up
with the electron beam steering magnets and has just had pre-amplifier
wires welded to the back of the diode array header.
(28k JPEG) A completed Digicon, with HV feed emerging
near the rectangular photocathode mask. The knob on the top is a
mounting fixture used to hang the detector within the FOS framework.
Flat ribbon cables emerging at the rear take 512 channels of spectral
information from the pre-amplifiers to the rest of the on-board
electronics, including customized FOS computers.
More Digicon Images
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