The scanner described follows the principles of the Hough-Powell digitizer, but a cathode ray tube is used as flying spot generator. Direction of scan can be 0 un. Concent 85% or 90 un. Concent 85% , number of lines can be 100 to 800, and scan time per line is 750 sec. Digitizing along the scan lines is done by starting an oscillator at the well-defined edge of the picture and counting its oscillations. In the perpendicular direction, the number of the scan lines will be used. The device will be calibrated at regular intervals by scanring a test pattern. Stability has been found to be better than 0.1% over periods of 30 sec. (A.G.W.)

"Einführung in die Theorie der Elektronenoptik." Optica Acta: International Journal of Optics, 4(3), p. 87