Electromagnetic Induction Spectroscopy (EMIS)
An object partly or wholly made of metals manifests a unique spectral response under a broadband EM interrogation. An EMIS spectrum, which depends on geometrical shape and metal compositions of an object, may be able to identify an object based on its spectral fingerprints. EMIS is a newly discovered phenomenology for hidden object identification (US Patent No. 5,963,035). There are many recent articles on the subject some of which may be found on this website.
EMIS Spectra for Some Ordnance and Landmines
