Filament-induced nonlinear hyperspectral fluorescence imaging

Hyperspectral fluorescence imaging is promising for many applications including gas sensing and imaging. However, achieving spectrally and spatially resolved images for quantitative multi-gas and multi-parameter analysis remains challenging, especially in a non-cooperative environment. Here, we report a simple technique, based on filament-induced nonlinear spectroscopy, for information-rich gas imaging. We obtained three-dimensional (3D) hyperspectral images for an alcohol/air flame with sub-millimeter spatial resolutions. For each hypercube, a broadband fluorescence fingerprint spectrum, containing 2500 spectral elements (350-600 nm at a spectral resolution of 0.1 nm), was acquired. This technique, with backward fluorescence detection, enabled high-spatial resolution point-wise imaging in a non-cooperative situation, e.g., in a sealed tube. Without meticulously arranged cameras, the technique may open up new opportunities for remote gas imaging and tomography.