Noncontact 2-D Temperature Imaging of Metallic Foils Using Electromagnetic Tomography

We propose a noncontact 2-D temperature imaging method for metallic foils using electromagnetic tomography (EMT), where a coil array is placed close to the target metallic foil on one side, and voltage data are acquired as the excitation coils are switched. The voltage data are then used to solve an inverse problem to reconstruct the 2-D conductivity distribution of the target, which is then converted to a 2-D temperature distribution based on the temperature–conductivity characteristics of the metal. We evaluated the effects of the excitation and measurement conditions on the temperature output characteristics of an aluminum foil target based on a simulation and designed a detector consisting of a 16-coil array that is suitable for temperature measurement. We then applied the detector to noncontact imaging of the 2-D temperature distribution for a
$120\times120$
mm region of aluminum foil over a range of
$20 ^{\circ} \text {C}$
–
$100 ^{\circ} \text {C}$
. The experimental results indicated that the proposed method could successfully image time-varying temperature distributions over obstacles. The proposed method does not require physical or optical access to the target during measurement and is scalable. Thus, it is expected to be a new option for temperature imaging.