Introduction

Instrumentation

4 Modes - The way the coil(s) are wired and interface with the test equipment
- Absolute: single coil for generation and sensing
- Differential: two active coils with opposite windings, inspect difference in signal
- Reflection: two coils, one for generation and one for sensing
- Hybrid: mix of the three, e.g. reflection & differential; or conventional coil but non-coil sensing like Hall Effect
4 Configurations: how the coil(s) are packaged to interact with test area
- Surface (aka Pancake): handheld, in contact with test surface
  - Wide coils for large areas, pencil-style for restricted areas
- Bolt Hole: for use with bolt hold scanner, housing matches hole diameter, is inserted and rotated
- ID/Bobbin: inserted into pipe, inspects from inside out
- OD/Encircling: surrounds pipe, inspects from outside in