US Patent 7750300 Thermo-optic system employing self reference

A thermo-optic system, which may be used for example in thermal imaging, includes an array of optical elements each having a thermally responsive optical property, the optical elements including signal elements and reference elements configured to provide (1) a common-mode response of the optical property to ambient temperature and (2) a differential-mode response of the optical property to a thermal signal appearing across the array of optical elements. The system also includes an optical readout subsystem configured to (1) illuminate the array of optical elements with optical energy at a readout wavelength corresponding to the optical property so as to generate a composite optical signal having common-mode and differential-mode signal components corresponding to the common-mode and differential-mode responses respectively of the signal and reference elements, and (2) filter the composite optical signal to generate a filtered optical signal being substantially the differential-mode image component.