Eddy current guage for measuiring film thicknesses - on metals

摘要

The eddy current gauge can be used also for determination of surface shape of complex metal objects and has an inductor coil whose ferrite core has at least one air gap, in which the stray field interacting with the test-piece is generated. A plug of highly electrically conductive material is placed in the air gap and aligns the stray field with its axis. The plug extends from the gap into the space enclosed by the core. A doubt air gap core has such a plug in each air gap and the outer surface of the core is clad with an electrically good conductor; each plug is in contact with this so that a completely closed electric winding is formed by the shielding.