Inspection method

1. A method for inspecting a test object for defects using an ultrasonic probe that includes a transmitter for transmitting ultrasound, a wedge holding the transmitter at an angle allowing the ultrasound transmitted from the transmitter to propagate as surface waves along a surface area of the test object, and a receiver for receiving an ultrasonic echo produced by reflection of the ultrasound, the method comprising the steps of:

placing the ultrasonic probe on the test object;

transmitting the ultrasound from the transmitter into the wedge such that the surface waves propagate along the surface area of the test object; and

determining that there is a defect in a part of the test object overlapped with the wedge when the receiver receives an ultrasonic echo, after the transmission of the ultrasound by the transmitter, in a time shorter than a time required to receive a front end-reflected ultrasonic echo produced by reflection of the surface waves at a front end of the wedge in a propagation direction of the surface waves.

2. The method according to claim 1 , wherein

in the wedge placing step, the wedge includes an absorber disposed at the front end thereof in the propagation direction for absorbing the ultrasound.

3. The method according to claim 1 , wherein

in the wedge placing step, the wedge is made of polyetherimide.