Abstract: A diaphragm tensioning arrangement for a Sell-type ultrasonic transducer assembly is disclosed. The transducer includes a fixed backplate having a substantially planar electrically conductive front surface and a diaphragm having a front surface and back surface, the back surface of the diaphragm overlying the substantially planar surface of the backplate. The diaphragm includes an insulating layer adapted to contact the backplate and a conducting layer electrically isolated therefrom. The diaphragm tensioning arrangement includes means for applying a load to the front surface of the diaphragm in order to maintain diaphragm tension. A groove disposed in the backplate extension or base has at least one groove opening into its front surface. A tension element engages the front surface of the diaphragm pressing a portion thereof into the groove in order to maintain diaphragm tension.

Abstract: A method for calibrating a thickness measuring system that automatically compensates for inadvertent movements of the probe. In one emobodiment, a conventional thickness measuring system is provided that incorporates a pair of spaced apart opposing ultrasonic sensors that are positioning a known distance apart. A target is passed between the sensors and the distance from each sensor to the target is measured. The thickness of the target can be determined by subtracting the distance from each sensor to the target from the known distance between the targets. The improvement, being a method of periodically checking the distance between the sensors to compensate for movements of the sensor relative to each other due to such effects as thermal expansion or inadvertent movements. The automatic compensation technique can be applied to a single probe system as well.

Abstract: A method for calibrating a thickness measuring system that automatically compensates for inadvertent movements of the probe. In one embodiment, a conventional thickness measuring system is provided that incorporates a pair of spaced apart opposing ultrasonic sensors that are positioning a known distance apart. A target is passed between the sensors and the distance from each sensor to the target is measured. The thickness of the target can be determined by subtracting the distance from each sensor to the target from the known distance between the targets. The improvement, being a method of periodically checking the distance between the sensors to compensate for movements of the sensor relative to each other due to such effects as thermal expansion or inadvertent movements. The automatic compensation technique can be applied to a single probe system as well.

Abstract: An ultrasonic transducer and method for detecting the distance to an object using ultrasonic energy. The transducer includes a foil which creates ultrasonic energy. First and second reference surfaces are provided which are spaced between the transducer and the object. The two reference surfaces provide for immunity against temperature and positional changes.