Digicon Photon Detectors

(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

Back to the CASS Home Page