Traffic Telematics (Verkehrstelematik)

An electron beam memory system comprises a substrate mounted for rotation and supporting an information storage medium. Means are provided for rotating the substrate. An electron gun comprises a field emission cathode having an emitting tip, anode means, and means for developing and applying between the tip and the anode means a predetermined accelerating potential for forming a high brightness electron source at the tip and for causing an electron beam to be formed through the anode means. The gun includes focus lens means for receiving the beam and for forming a very small yet intense electron beam probe at a predetermined first focal distance therefrom. A high rate digital beam pulsing system comprises voltage pulse generating means for developing a series of voltage pulses of predetermined magnitude and duration, and means for applying the pulses to the gun such that the pulses add to or subtract from the accelerating potential to thereby cause the focus lens means to focus the beam at a predetermined second focal distance different from the first focal distance. The gun is positioned relative to the recording medium such that one of the first and second focal distances corresponds to the distance between the focus lens means and the recording medium.