Generation of a temperature map
Generating an accurate and sensitive temperature map over a non-planar surface by capturing a polarimetric thermal image from a non-planar surface. The non-planar surface includes a surface element which emits thermal electromagnetic emission responsive to a temperature of the surface element. Thermal electromagnetic emission is directed to an image element of an image sensor. A polarisation state and intensity are measured of the ray of thermal electromagnetic emission from the surface element. Responsive to the polarization state and the intensity, an angular orientation of the surface element is determined. A temperature of the surface element is determined by estimating the thermal emission normal to the surface element responsive to the angular orientation of the surface element and the intensity of the ray of thermal electromagnetic emission emitting from the surface element.
1 . A method comprising:
capturing a polarimetric thermal image from a non-planar surface, wherein the non-planar surface includes a surface element, wherein the surface element emits thermal electromagnetic emission responsive to a temperature of the surface element, wherein a ray of the thermal electromagnetic emission is directed to an image element of an image sensor;
(i) measuring a polarization state and an intensity of the ray of thermal electromagnetic emission emitting from the surface element;
(ii) responsive to the polarization state and the intensity, determining an angular orientation of the surface element;
(iii) determining a temperature of the surface element by estimating the thermal emission normal to the surface element responsive to the angular orientation of the surface element and the intensity of the ray of thermal electromagnetic emission emitting from the surface element; and
for a plurality of surface elements of the non-planar surface, performing said (i) measuring, (ii) determining an angular orientation and (iii) determining a temperature, thereby generating a temperature map over the non-planar surface;
prior to (iii) determining the temperature of the surface element, performing a calibration by measuring thermal electromagnetic radiation emittance or reflectance from a calibration surface as a function of angle; and
said (iii) determining the temperature of the surface element further responsive to the calibration.
2 . The method of claim 1 , wherein the non-planar surface is living biological tissue.
3 . The method of claim 1 , further comprising:
presenting a surface contour of the non-planar surface and the map of temperatures superimposed on the presented surface contour.
4 . The method of claim 1 , wherein the map of temperatures is independent of the respective angular orientations of the surface elements.
5 . The method of claim 1 , wherein said (iii) determining the temperature includes:
extrapolating from the intensity of thermal emission as measured from the surface element emitting at a non-zero emission angle to an intensity of thermal emission expected at a normal to the surface element.
6 . A system comprising: a polarimetric camera and a processor connectable thereto, the system configured to perform the steps comprising: capturing a polarimetric thermal image from a non-planar surface, wherein the non-planar surface includes a surface element, wherein the surface element emits thermal electromagnetic emission responsive to a temperature of the surface element, wherein a ray of the thermal electromagnetic emission is directed to an image element of an image sensor; for a plurality of surface elements of the non-planar surface:
(i) measuring a polarization state and an intensity of the ray of thermal electromagnetic emission emitting from the surface element;
(ii) responsive to the polarization state and the intensity, determining an angular orientation of the surface element;
(iii) determining a temperature of the surface element by estimating the thermal emission normal to the surface element responsive to the angular orientation of the surface element and the intensity of the ray of thermal electromagnetic emission emitting from the surface element; and from the plurality of temperatures determined respectively for the surface elements of the non-planar surface, generating a map of temperatures over the non-planar surface, prior to determining the temperature of the surface element, calibrating by measuring thermal electromagnetic radiation emittance or reflectance from a calibration surface as a function of angle; and determining the temperature of the surface element further responsive to the calibration.
7 . The system of claim 6 , wherein the non-planar surface is living biological tissue.
8 . The system of claim 6 , further comprising:
a display;
the system further operable to:
present on the display a surface contour of the non-planar surface and the map of temperatures superimposed on the presented surface contour.
9 . The system of claim 6 , wherein the map of temperatures is independent of the respective angular orientations of the surface elements.
10 . The system of claim 6 , further operable to:
extrapolate from the intensity of thermal emission as measured from the surface element emitting at a non-zero emission angle to an intensity of thermal emission expected at a normal to the surface element.
11 . A non-transitory computer readable medium having software instructions stored thereon comprising: inputting a polarimetric thermal image captured from a non-planar surface, wherein the non-planar surface includes a surface element, wherein the surface element emitted thermal electromagnetic emission responsive to a temperature of the surface element, wherein a ray of the thermal electromagnetic emission is directed to an image element of an image sensor; wherein the polarimetric thermal image includes a polarization state and an intensity of the ray of thermal electromagnetic emission emitted from the surface element; for a plurality of surface elements of the non-planar surface:
(i) inputting a polarization state and an intensity of the ray of thermal electromagnetic emission emitting from the surface element;
(ii) responsive to the polarization state and the intensity, determining an angular orientation of the surface element;
(iii) determining a temperature of the surface element by estimating the thermal emission normal to the surface element responsive to the angular orientation of the surface element and the intensity of the ray of thermal electromagnetic emission emitted from the surface element; and from the plurality of temperatures determined respectively for the surface elements of the non-planar surface, generating a map of temperatures over the non-planar surface; inputting a calibration previously performed by measuring thermal electromagnetic radiation emittance or reflectance from a calibration surface as a function of angle; and determining the temperature of the surface element further responsive to the calibration.
12 . The computer readable medium, of claim 11 , wherein the non-planar surface is living biological tissue.
13 . The computer readable medium of claim 11 , having further software instructions stored therein to:
present a surface contour of the non-planar surface and the map of temperatures superimposed on the presented surface contour.
14 . The computer readable medium of claim 11 , wherein the map of temperatures is independent of the respective angular orientations of the surface elements.
15 . The computer readable medium of claim 11 , having further software instructions stored therein to:
determine said temperature by extrapolating from the intensity of thermal emission as measured from the surface element emitting at a non-zero emission angle to an intensity of thermal emission expected at a normal to the surface element.