High signal-to-noise ratio wedges for oblique incidence in ultrasonic testing

It is experimentally shown that ultrasonic transmission through a column of couplant, with a thin film, at the end, produces greater amplitudes than through a piece of acrylic with the same length. This suggests the use of a wedge that could yield a greater signal-to-noise ratio than that of commercial wedges involved in oblique incidence ultrasonic inspection. The suggestion has been pursued, and the effects: on a weld are presented.