Reference Reflector

A reference reflector is a machined feature in a calibration block — typically a side-drilled hole, flat-bottom hole, or notch — used as a known target to set instrument gain and build sizing curves.

Definition

Reference reflectors are deliberately machined targets of precisely known size and orientation. They provide the repeatable echoes against which the ultrasonic system is calibrated. Common types are side-drilled holes, flat-bottom holes, and surface notches.

Related terms

  • Side-Drilled Hole (SDH) — A side-drilled hole is a cylindrical reference reflector drilled perpendicular to the inspection surface, used as a length-independent angle-beam target for building DAC curves and verifying sensitivity.
  • Flat-Bottom Hole (FBH) — A flat-bottom hole is a reference reflector drilled into a calibration block to a precise depth with a flat bottom perpendicular to the beam axis, used as a known disc-shaped target for normal-beam sizing.
  • Notch Reference — A notch reference is a machined surface-breaking notch of known depth, length, and width used to calibrate ultrasonic systems for surface-crack detection and to set acceptance thresholds for shear-wave inspection.
  • Calibration Block — A calibration block is a reference specimen with known geometry and reference reflectors (side-drilled holes, flat-bottom holes, notches) used to set ultrasonic instrument sensitivity, range, and angle prior to inspection.

More equipment terms

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Where this comes up in practice

Terms like this one appear in three places that matter commercially: the written practice that governs how your personnel are qualified, the procedures and technique sheets that define how an examination is actually performed, and the evidence an auditor or client asks for when they want to know why an inspection was accepted. Getting the terminology right is the easy part; being able to produce the qualification record, the calibration traceability and the procedure revision that applied on the day of the inspection is the part that decides audits.

Atlantis NDT provides NDT training and certification against ASNT SNT-TC-1A and ISO 9712, ASNT Level III consulting for written practices and procedure approval, inspection management software that holds qualification, calibration and procedure-revision evidence in recoverable form, and an asset integrity platform that binds inspection results to the asset they describe. Browse the full NDT glossary or ask a Level III directly.