Structured illumination with thermal imaging (SI-TI): A dynamically reconfigurable metrology for parallelized thermal transport characterization

Abstract

The recent push for the “materials by design” paradigm requires synergistic integration of scalable computation, synthesis, and characterization. Among these, techniques for efficient measurement of thermal transport can be a bottleneck limiting the experimental database size, especially for diverse materials with a range of roughness, porosity, and anisotropy. Traditional contact thermal measurements have challenges with throughput and the lack of spatially resolvable property mapping, while non-contact pump-probe laser methods generally need mirror smooth sample surfaces and also require serial raster scanning to achieve property mapping. Here, we present structured illumination with thermal imaging (SI-TI), a new thermal characterization tool based on parallelized all-optical heating and thermometry. Experiments on representative dense and porous bulk materials as well as a 3D printed thermoelectric thick film (∼50 μm) demonstrate that SI-TI (1) enables paralleled measurement of multiple regions and samples without raster scanning; (2) can dynamically adjust the heating pattern purely in software, to optimize the measurement sensitivity in different directions for anisotropic materials; and (3) can tolerate rough (∼3 μm) and scratched sample surfaces. This work highlights a new avenue in adaptivity and throughput for thermal characterization of diverse materials.

Structured illumination with infrared imaging for measuring thermal conductivity

“…Thermal metrologies can be broadly classified as contact and non-contact based [2], [1] . Traditional contact based techniques are often slow or lack spatial resolvability.…”

“…Furthermore, none of the traditional techniques offer parallelized measurements. Towards this end, Structured Illumination with Thermal Imaging (SITI) [1] is an all-optical pump-probe high-throughput thermal characterization technique developed by our group. The first generation of SITI was built using an LED with a Digital Micromirror Device (DMD) to "pump" heat, and thermoreflectance based Microsanj MTIR120 setup to "probe" the temperature.…”

“…By dynamically reconfiguring heating patterns through simple software-control of DMD, thermal property mapping was immensely simplified by the first generation of SITI. Thermoreflectance, the approach used in the first generation [1] , is a delicate technique to obtain spatial variation in temperature. In comparison, using an IR camera to obtain a 2D temperature map is well-established and commercially available.…”

“…In comparison, using an IR camera to obtain a 2D temperature map is well-established and commercially available. It also reduces the need for a dedicated transducer layer (100 nm gold in [1]). Furthermore, a commercial projector provides the same function as DMD + LED, i.e.-spatial and temporal variation of projected light with lower cost and higher power.…”