Abstract: A method of testing a material sample for defects, comprising the steps of applying a test signal to the material sample, receiving a return signal from the material sample and analysing the return signal to determine whether the material sample is defective. In one aspect of the present invention the steps of receiving a return signal and analysing it include the step of selecting a frequency range to reduce the effect of potentially interfering signals. In another aspect of the present invention a reference signal obtained from a non-defective sample is subtracted from the return signal to give a difference result and the difference result is indicative of whether the material sample is defective. Apparatus for carrying out the above-defined methods are also provided.

Abstract: A method of testing a material sample for defects, comprising the steps of applying a test signal to the material sample, receiving a return signal from the material sample and analysing the return signal to determine whether the material sample is defective. In one aspect of the present invention the steps of receiving a return signal and analysing it include the step of selecting a frequency range to reduce the effect of potentially interfering signals. In another aspect of the present invention a reference signal obtained from a non-defective sample is subtracted from the return signal to give a difference result and the difference result is indicative of whether the material sample is defective. Apparatus for carrying out the above-defined methods are also provided.

Abstract: The present invention provides a probe for non-destructive testing of items. The probe is movable over a surface of a test item and includes a displacement sensor means for providing a displacement signal indicative of the spatial displacement of the probe over the test item as the probe is moved over the test item. The invention also provides the above-defined probe with a receiver for receiving a return signal from the non-destructive testing of the item and a non-destructive testing system comprising the probe.

Abstract: The present invention provides a probe for non-destructive testing of items. The probe is movable over a surface of a test item and includes a displacement sensor means for providing a displacement signal indicative of the spatial displacement of the probe over the test item as the probe is moved over the test item. The invention also provides the above-defined probe with a receiver for receiving a return signal from the non-destructive testing of the item and a non-destructive testing system comprising the probe.

Abstract: A fluid meter has a central cylindrical section in which time-of-flight ultrasonic measurements can be made between acoustic transducers disposed in spaced apart enlarged end sections. The central section has a smaller diameter than do the end sections. Transitional regions join the end sections to the central cylindrical section. The transducers are located at least in part in the transitional regions. The transitional regions in the intermediate central section are generally shaped such that in combination with the shape and location of the transducers, pressure drops along the central section along with back-reflections of acoustic pulses from the transitional regions are reduced.