A Spectral-Emissivity-Corrected Method for Temperature Inversion from CCD Images

Accurate high-temperature field characterization is important for explosion diagnostics, laser-matter interaction, combustion monitoring, and related thermal processes. This work presents an integrated thermometry framework combining fiber-optic spectrometry with monochrome imaging. Its central contribution is not a new multispectral principle or optimization algorithm, but an integration-time-dependent radiometric calibration framework coupled with representative spectral-emissivity transfer under clearly stated applicability conditions. Its central element is a three-parameter radiometric calibration model in which camera integration time is explicitly included, so that radiance conversion can be performed across the experimentally calibrated integration-time range without repeating a separate fixed-exposure calibration for each setting. Multiwavelength spectral radiance is used to jointly retrieve temperature and a continuous, second-order polynomial emissivity function with a genetic algorithm serving as the global optimizer. The emissivity function obtained from a representative spectral sampling region is then transferred to the imaging model for pixelwise temperature inversion; this step assumes that the material and surface state are sufficiently uniform over the region to which the function is applied. The method is examined using steady-state tungsten-halogen-lamp measurements with nominal color temperatures of 2200-2800 K and a transient laser-heated 316L stainless-steel case. Agreement with a Wien-based estimate is used as an internal spectral-consistency check rather than as an independent traceable accuracy validation. In the transient case, the retrieved spectral-field-of-view temperature increased from 2311.9 to 2398.5 K over 50-60 s, and the reconstructed images reproduced the corresponding increase in the central high-temperature region. The present results demonstrate the feasibility of coupling integration-time-dependent calibration with measured spectral-emissivity transfer for two-dimensional temperature reconstruction, while the achievable absolute accuracy remains subject to detector linearity, emissivity-model validity, spatial emissivity uniformity, radiometric calibration, and independent reference validation.