Digicon

Abstract: Publisher Summary This chapter discusses the photon detection experiments with thinned CCDs. It describes results of a program to develop high speed photon noise limited astronomical imaging techniques using CCDs. CCD imaging in the direct optical input mode is quite useful, and has important applications in astronomy. In order to investigate CCD-Digicon photoelectron imaging characteristics without being subject to complications and expense due to phototube processing, a demountable Digicon system was utilized during the fall of 1977. The general CCD system that has been developed shows promise of being a powerful tool, particularly with the potential addition of fast external memory. The demountable Digicon tests have shown the viability of single photoelectron imaging with CCDs, and, along with the computer simulation studies mentioned in the chapter, provide valuable insights into the construction of future systems. The CCD/image tube system has also demonstrated single photon sensitivity and has shown that with care it can be a respectable high speed photon noise limited astronomical instrument.

Abstract: Publisher Summary This chapter provides an overview of Digicon applications in astronomy. The Digicon system consists of the Digicon tube itself with its associated electronics, a set of interfacing modules built to CAMAC standards, and a Nova 820 minicomputer with peripherals to control the Digicon and to record and display the data. The new Digicon has an S-20 photocathode with peak quantum efficiency ∼25%. The diode array consists of a line of 200 diodes each 40 μm wide by 300 μm long on a 50 μm pitch with five additional diodes at either end, patterned to aid lining up of the image on the array, and 2 large “background detection” diodes. In D-40, the array is made up of 40 (90 × 90 μm 2 ) diodes on a 100 μm pitch. In general, the D-40 is used as a test bed to demonstrate the concepts for hardware and applications. It is suggested to use the D-40 for direct deep sky observations because the diode geometry is appropriate for this task. The instrument can be applied to quantitative studies where statistical errors must be clearly specified.