Planck spectroscopy

TL;DR

Planck spectroscopy is a novel technique that measures surface spectral emissivity by leveraging temperature-dependent thermal emission, eliminating the need for traditional wavelength-selective optical components.

Contribution

This work introduces and experimentally validates a simple, cost-effective spectroscopic method based solely on temperature control and thermal emission measurements.

Findings

Successfully demonstrated in the mid-infrared range (3-13 μm)

Achieved spectral resolution of approximately 1 μm

Potential for low-cost hyperspectral imaging applications

Abstract

All spectrometers rely on some mechanism to achieve spectral selectivity; common examples include gratings, prisms, and interferometers with moving mirrors. We experimentally demonstrated and validated a spectroscopic technique -- here dubbed Planck spectroscopy -- that measures the spectral emissivity of a surface using only a temperature-controlled stage and a detector, without any wavelength-selective optical components. Planck spectroscopy involves the measurement of temperature-dependent thermally emitted power, where the spectral selectivity is realized via the temperature- and wavelength dependence of Planck's law. We experimentally demonstrated and validated Planck spectroscopy in the mid infrared, for wavelengths from 3 to 13 um -- limited primarily by the bandwidth of our detector -- with resolution of approximately 1 um. The minimalistic setup of Planck spectroscopy can be implemented using infrared cameras to achieve low-cost infrared hyperspectral imaging and imaging ellipsometry.