ABSTRACT
We introduce the design of a scalable, modulated long-wave infrared source. The design makes use of a pseudo-blackbody heating element array, which radiates into a custom aluminum integrating cavity. The elements possess low thermal capacitance, enabling temporal modulation for improved signal isolation and dynamic background removal. To characterize performance, deflectometry measurements were made using both the new source design and a traditional tungsten ribbon source, which possess similar source irradiance and identical emission profile dimensions. Measurements from a ground glass flat and an aluminum blank demonstrated the new source produces a signal-to-noise ratio four times greater than that of the ribbon. Thermal imaging demonstrated improved source geometry and signal stability over time, and further, the new design measured a previously untestable hot aluminum flat (150 °C). The new design enables high-contrast thermal measurement of surfaces typically challenging to infrared deflectometry due to high surface roughness or intrinsic thermal noise generation.
