Depth thermography: non-invasive 3D temperature profiling using infrared thermal emission

TL;DR

Depth thermography is a novel non-invasive infrared technique that measures the internal temperature distribution of objects in three dimensions, enabling volumetric thermal analysis without contact.

Contribution

This paper introduces depth thermography, a new method using infrared emission spectra to obtain 3D temperature profiles beneath surfaces, unlike traditional surface-only thermography.

Findings

Successfully demonstrated 3D temperature profiling in fused-silica

Potential for non-contact volumetric temperature measurement in various materials

Compatible with hyperspectral imaging for detailed thermal analysis

Abstract

We introduce a technique based on infrared thermal emission, termed depth thermography, that can remotely measure the temperature distribution beneath the surface of certain objects. Depth thermography utilizes the thermal-emission spectrum in the semitransparent spectral region of the target object to extract its temperature as a function of depth, in contrast with conventional thermography, which uses the spectrally integrated thermally emitted power to measure the surface temperature. Coupled with two-dimensional imaging, e.g., using an infrared hyperspectral camera or scanning a single-pixel spectrometer, this technique can yield volumetric temperature distributions. We carried out a proof-of-concept experiment on an asymmetrically heated fused-silica window, extracting the temperature distribution throughout the sample. Depth thermography may enable noncontact volumetric temperature measurements of microscopic objects such as multilayer electronic devices or macroscopic volumes of liquids and gasses as well as simultaneous all-optical measurements of optical and thermal properties.