Method of measuring spot size of cathode-ray tube

THE determination of the spot size of a cathode-ray tube has been, at best, a subjective process. Thus, the shrinking-raster method of measuring spot size relies on the judgment of the observer to determine when a set of lines appears to merge. Similarly, any attempt to measure the spot diameter with a microscope is also dependent upon the observer because of the way the flux density varies over the area of the spot.1