Image Sensor, Vidicon, SIT

This is a silicon intensified phototube (SIT) used by James Westphal and his group as an astronomical imaging tube. Manufactured by RCA, it is a Vidicon imaging tube modified by the addition of a silicon photodiode. The electrons that are released from the conventional photosensitive coating on the face of the tube are accelerated onto the silicon photodiode by an electrostatic field. The back of this target is scanned by beam of electrons; these create a current when they meet an area of the target that has been exposed to light. This current is then converted electronically into an image. Astromers were astonished by the SIT's very high sensitivity on its first use on the 200 inch Mt. Palomar telescope. The tape that accompanies this artifact is a record of that image in digital form. This SIT tube is about 2000 times more sensitive than the SIVIT tube that was used before. It was used extensively in studies of the stars.

The California Institute of Technology donated this object to the Museum in 1983.