Patent ID: 7701206

Claim:
A method for non-contact determination of sought properties of an object to be measured, by using electromagnetic induction, the method comprising: generating a first electromagnetic field in a first transmitter coil placed on a first side of the object to be measured, detecting the first electromagnetic field penetrating through the object to be measured by a first receiver coil placed on a second side of the object to be measured, placing a first control coil near the first transmitter coil, generating a change in the first electromagnetic field of the first transmitter coil, detecting the field change in the first control coil, detecting the field change in the first receiver coil, determining a first difference in time for the detection of the field change in the first control coil and in the first receiver coil, respectively, determining a time of penetration through the object to be measured, and determining from the time of penetration the thickness or electrical conductivity of the object to be measured.