Fluorescence-Detected Photothermal IR Microscopy

The remarkable sensitivity of fluorescence to subtle changes in temperature supports photothermal imaging with a spatial resolution and point-spread function defined by fluorescence imaging. Instrumentation and methods for photothermal IR microscopy are described integrating a diverse suite of IR sources, including 32-channel independently addressable quantum cascade laser (QCL) arrays, dual-comb IR sources based on matched QCLs, broadband IR from a synchrotron source, and benchtop QCL arrays. Practical considerations for implementation will be discussed, together with advantages in combining simultaneous fluorescence-detected and optical photothermal IR microscopy. Future prospects for super-localized IR microscopy are also considered.