Abstract: A method consisting in that a portion of the working layer is acted upon at first by a uniform thermal field and simultaneously or successively by a uniform vector field whose vector lines are perpendicular to the carried surface. At least one of the fields is obtained by converting the electrical signals transmitting the information being recorded. When recording on a carrier portion heated to a temperature higher that the softening temperature of the working layer binder (3), particles (4) are aligned along the vector lines whereby optical density of said area within the medium is changed according to the recorded information. The time is started to be fixed at the moment the vector field is no longer applied.

Abstract: An acoustic surface wave interdigital transducer comprises a main and auxiliary rows of electrodes arranged on a piezoelectric substrate. The main row of electrodes comprises a first group of electrodes galvanically connected to a first contact area and a second group of electrodes parallel to the electrodes of the first group and disposed therebetween so that there are formed overlapping portions having the same length. The auxiliary row of electrodes comprises a third group of electrodes galvanically coupled to the second contact area and a fourth group of electrodes parallel to the electrodes of the third group connected directly to the corresponding electrodes of the second group of the main row and disposed between the electrodes of the third group so as to form overlapping portions of electrodes of both groups, said portions having a variable length. The electrodes of the second group of the main row are connected to the second contact area through capacitances.