The Quadrant Multiplier Phototube, a New Star-Tracker Sensor

Abstract

The quadrant multiplier phototube developed for use as a navigational aid is described. The tube contains four independent and adjacent semitransparent photocathode quadrants in a common image plane. By means of a retarding field three of the four photocathode segments are biased off during a quarter cycle while emission from the fourth is collected by the electron multiplier. Operating sequentially the photocathode quadrants perform the function of four multiplier phototubes in an all-electronic nulling-type tracker. No rotating reticles or mechanical choppers are required in the optical system. Position information of the image is discussed in relation to the size of the image spot. The performance characteristics are given in terms of nulling precision and signal-to-noise ratio for stars of different visual magnitudes.