What is a reference reflector and how is it used during UT calibration?

• A. It is a known reflector used to set gain.
• B. It is a material sample used to verify velocity.
• C. It is a standard that measures time-of-flight only.
• D. It is a known reflector used to set gain and verify response; calibrate baseline.

Answer: (D)

A reference reflector provides a known, repeatable echo that lets you calibrate the UT system. By using a reflector with a defined geometry and material, you can adjust the instrument’s gain so the reference echo reaches a specific, expected amplitude. It also verifies that the system’s response matches what you expect, ensuring the display and measurements are consistent with the calibration setup. In short, it establishes a baseline: the known signal you compare all future inspections against. This is why it’s described as a known reflector used to set gain, verify response, and calibrate the baseline. It’s broader than just measuring time-of-flight or velocity, which are other parts of calibration.