This invention concerns a method of recording wide-band signals on a thermoplastic film. The signal to be recorded is converted to an intensity modulation of a beam of electrons which is directed at the surface of a thin thermoplastic film carried on a conductive substrate. The film is rotated in its own plane and simultaneously translated so that the beam scans the film in a track which follows a spiral path. The deposition of charge produces after heating of the film a spatial modulation of the film. The intensity of the beam and the beam's impingement on the film is controlled in order that the charge pattern is appropriate for the formation of a spiral groove which is substantially invariant in cross-section but varies in depth along its direction of progression in accordance with the signal that modulates the intensity of the beam of electrons. The recording thus made can be used for the production of video discs capable of mechanical playback.