Abstract

Apparatus for continuously orienting an ultrasonic transducer so that the emitted ultrasonic waves remain at a normal angle of incidence to the opposing surface of an object while the transducer is being moved laterally across the surface in order to inspect the subsurface composition of the object. The sensor casing which contains the ultrasonic transducer pivots about one end of a tubular support arm, while the other end of the support arm pivots about a gearbox casing. A drive shaft passes through the support arm and has a miter gear on each end. One miter gear is engaged with a miter gear attached to the gearbox casing, and the other is engaged with a miter gear attached to the sensor casing so that the rotation of the drive shaft causes the simultaneous rotation of the support arm about the gearbox casing and, in the opposite direction, the rotation of the sensor casing about the support arm. The gearbox casing is attached to a carriage and has the freedom to roll relative to it. The carriage is a part of a translational motion apparatus which continuously moves the sensor casing across the surface of the object. The gear ratios are calculated so that, in conjunction with rolling the apparatus, a normal angle of incidence between the emitted ultrasonic waves and the surface of the object can be obtained regardless of the local orientation of the surface.