Patent ID: 6907786

Claim:
A device for coupling ultrasonic waves into a solid body to be ultrasonically probed via a boundary surface located outside a closed volume comprising: at least one ultrasonic-wave transducer unit, which couples ultrasonic waves into the solid body via a gaseous coupling medium provided between the at least one ultrasonic-wave transducer unit and the boundary surface, wherein the ultrasonic waves generated by the at least one ultrasonic-wave transducer unit are directed into the closed volume, which is provided with at least a first opening and a second opening; the closed volume being bordered by a housing, in which the at least one ultrasonic-wave transducer unit is contained, including a housing surface spaced from the boundary surface which defines and extends outward from the second opening to define a channel between the housing surface and the boundary surface; and a source of gas providing a flow of gas producing an overpressure inside the closed volume which is directed into an interior of the closed volume through the first opening, and which exits the closed volume through the second opening which directly faces the boundary surface and flows through the channel outward from the second opening while contacting the housing and the boundary surface; and wherein the flow of gas passes through the second opening facing the boundary surface and flows between an upper side of the housing and the boundary surface and the boundary surface and upper surface extends radially relative to the second opening to define the channel, and a vacuum draws the housing toward the boundary surface to create a gas cushion in the channel of a thickness at which a force of attraction is created by the vacuum and a force of repulsion present due to a mass impulse of the flow of gas between the housing and the boundary surface are in equilibrium.