METHOD FOR MEASURING CLEARANCE TO METAL SURFACE AND DEVICE FOR ITS EMBODIMENT Russian patent published in 1998 - IPC

FIELD: no-contact measurement of object position. SUBSTANCE: device has voltage-controlled high-frequency generator, frequency meter and sensitive element. Generator output is connected to splitter, which arms are connected to phase detector inputs. Sensitive element is connected to one of splitter arms. Sensitive element is made as dielectric substrate which opposite sides carry applied conductors forming coupled retarding systems. Retarded electromagnetic wave is excited in sensitive element with magnetic field energy shifted to clearance region at frequency at which depth of magnetic field penetration into metal is considerably less than thickness of metal with surface under check. Time lag of this wave phase is measured by means of phase detector. Frequency in section of maximum phase variation is maintained by control of generator. Value of clearance is judged by generator frequency. EFFECT: higher measurement sensitivity. 14 cl, 12 dwg