Eliminating Biases in Quantitative Infrared Thermography: Stray Light and Readout Corrections for Accurate Heat‑Flux Measurements in Hypersonic Flows

Abstract

Accurate temperature measurements are essential for determining heat transfer rates by quantitative infrared thermography. Previous wind tunnel studies revealed systematic errors, as temperature changes confined to part of the field of view affected the thermosignal in the remaining image regions. Reflections were excluded as the cause. Using a black body emitter with a test specimen confirmed this mutual pixel influence in a specifically recreated laboratory experiment. Analysis identified two error sources known from photography as stray light and readout artefacts. Based on the obtained data, simplified correction models were developed, systematically validated and demonstrated on the wind tunnel data.