What calibration technique is required to account for differences in the exit point of each focal law?

The wedge delay technique is used to adjust for differences in the exit point of each focal law in phased array ultrasound testing. This calibration method compensates for variations in the sound path length that occurs due to different angle settings for the focal laws.

When a phased array transducer is used, each focal law corresponds to a specific angle of sound propagation. As a result, the distance the sound wave travels to reach the flaw changes with each focal law. Wedge delay applies a time delay that matches the time it takes for the sound to travel through the additional distance, effectively aligning the signals from different focal laws.

This alignment enhances the accuracy of the inspection by ensuring that the echoes from a defect arrive at the same time to the receiver, allowing for more precise image formation and flaw detection. Overall, employing wedge delay ensures that the data collected is coherent and representative of the actual conditions within the material being tested.