Apparatus and method for thermally mapping a component in a high temperature environment. An optical probe (10) has a field of view (14) arranged to encompass a surface of a component (15) to be mapped. The probe (10) captures infrared (IR) emissions in the near or mid IR band. An optical fiber (16) has a field of view to encompass a spot location (18) on the surface of the component within the field of view (14) of the probe (12). The fiber (16) captures emissions in the long IR band. The emissions in the long IR band are indicative of an emittance value at the spot location. This information may be used to calibrate a radiance map of the component generated from the emissions in the near or mid IR band and thus map the absolute temperature of the component regardless of whether the component includes a TBC.