WAVELENGTH

The distance needed in the propagation direction for a wave to go through a complete cycle.

VIBRATION

A rapid back and forth motion of a particle or solid.

ULTRASONIC TESTING

The transmission of high-frequency sound waves into a material to detect imperfections or to locate changes in material properties.

ULTRASONIC

A term referring to acoustic vibration frequencies greater than about 20,000 Hz.

TRANSMITTER

The transducer that emits ultrasonic energy.

TRANSIENT

Occurring when the system is changing with time; i.e., a steady-state has not been attained.

TRANSDUCER

Any device that converts an input signal to an output signal of a different form; it can be a transmitter or receiver in some cases.

TOMOGRAPHY

A method for determining the distribution of physical properties within the evaluated medium or element by inverting the results of a large number of measurements made in three dimensions (e.g., seismic, radar, resistivity, EM) between different source and receiver locations.

TIME DOMAIN

In NDE and geophysics refers to measurements analyzed according to their behavior in time. The usual alternative is frequency domain measurements.

TARGET

The object at which a NDE survey detection and characterization is aimed.