A system for the display of the joint probability of occurrence of a pair of analog data
Young, Joe Addison
Master of Science
This thesis proposes a system for recording three dimensional data which might be used to describe a joint probability distribution function. The proposed system is built around an Analab 1220 storage oscilloscope which uses a cathode ray tube with a potassium chloride screen. The optical density of the KC1 screen increases in a logarithmic fashion as a function of the time in which it is exposed to the 10 kv. electron beam of the cathode ray tube. Thus, if the screen has been calibrated, it should be possible to determine how long each part of the screen has been subjected to the influence of the electron beam simply by measuring the optical density of that particular area. The vertical and horizontal coordinates of a point on the screen represent two of the dimensions while the optical density at that point represents the third dimension. By using a closed circuit television camera to scan the illuminated surface of the KC1 screen, a signal proportional to the optical density of all parts of the screen might be Obtained which in turn could be used to produce a visual display of the three dimensional surface. This paper describes in some detail the behavior of the KC1 screen as it applies to the proposed system and compares it with the behavior of a photographic emulsion. A review is made of the various possible ways of scanning the KC1 screen and of the noise associated with each method. Because of the unstable nature of the alkali halide coloring under cathode ray bombardment, and because of the noise inherent in the scanning systems, it is concluded that the system will have only limited accuracy.