In ultrasonic testing, a method where the transducer is placed parallel to the test surface and waves enter perpendicular to the surface is called?

• A. Angle beam testing
• B. Straight beam testing
• C. Surface wave testing
• D. None of the above

Answer: (B)

This is normal-incidence ultrasonic testing, where the beam travels straight into the material and returns along the same path. When the transducer is placed parallel to the test surface, the emitted waves enter perpendicular to that surface, giving a straight, non-refracted path. This approach is called straight beam testing. It provides a direct, simple travel path, making accurate thickness measurements via the back-wall echo and easy detection of defects oriented perpendicular to the surface. In contrast, angle beam testing uses a wedge to bend the beam to an oblique angle, and surface wave testing relies on waves that travel along the surface rather than into the depth.