1. CHARACTERISATION OF THIN FILMS IN ORDER TO ACHIEVE IMPEDANCE MATCHING WITH LIQUID HELIUM
- Author
-
C. Chapelier and N. Lockerbie
- Subjects
Materials science ,business.industry ,Liquid helium ,Acoustic interferometer ,Impedance matching ,Acoustic microscopy ,Acoustic wave ,law.invention ,Transducer ,Optics ,Computer Science::Sound ,law ,business ,Acoustic impedance ,Electrical impedance - Abstract
In order to study acoustic waves in liquid Helium or for cryogenic acoustic microscopy, it is necessary to match the very low impedance of the liquid to the impedance of the transducer. One way to do it, is to deposit on the solid one or several quarter-wave layers at the interface with the liquid. In order to measure this transmission, we have constructed an alignment system for 9-10 GHz longitudinal sound waves in a quartz rod at 1.5 K. It allows us to deduce accurately the effective transmission in liquid Helium from the acoustic impedance, the sound velocity and the damping of the waves in the films.
- Published
- 1991
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