In contact testing, what is the entry surface indication sometimes referred to as?

In the context of contact testing in ultrasonic testing (UT), the entry surface indication is characterized by the first reflection received after the ultrasonic pulse travels through the coupling medium and encounters the test material's surface. This indication occurs as the pulse interacts with the entry surface of the test piece.

It is often referred to as the "initial pulse" or simply the "entry surface indication," as these terms describe the same phenomenon: the very first echo that represents the reflection from the boundary between the transducer and the test material.

The term "main bang" or "transmitter pulse," while related to the operation of the transducer, typically refers to the initial burst of ultrasonic energy emitted rather than the reflection from the material surface. Understanding that these terminologies are specific to different aspects of the pulse—one referring to the launch of the ultrasonic wave and the other to its reflection—is crucial for clarity in interpretation during testing.

Thus, recognizing the entry surface indication as distinct from these earlier terms helps to clarify why selections that reference the "main bang" do not accurately describe the indication being queried. This precision in terminology aids in avoiding confusion during analysis and reporting of ultrasonic test results.