Improvements in or relating to ultrasonic delay lines

摘要

846,864. Ultrasonic delay lines. MULLARD RADIO VALVE CO. Ltd. July 27, 1956 [July 29, 1955], No. 22072/55. Class 40(8). [Also in Group XXII] A piezo-electric transducer of e.g. quartz or barium titanate is attached to the face of a metal or glass delay line by evaporating indium or tin on to the two surfaces to be joined and then pressing them together, the whole process being carried out in a vacuum at a temperature above room temperature. The parts may be heated before they are put into the vacuum chamber or means may be provided for raising them to a desired temperature (e.g. 140‹ C. for indium) inside the chamber. A manipulator is used to press the parts together. The pressing may be completed outside the chamber. The evaporated layers may have a thickness of about one quarterwavelength in order to provide a matching section. In order to determine the thickness, means to measure the resistance of the layers as evaporation proceeds may be provided.