  Scattering-type scanning near-field optical microscopy (s-SNOM), and its
derivate, Fourier transform infrared nanospectroscopy (nano-FTIR) are emerging
techniques for infrared (IR) nanoimaging and spectroscopy with applications in
diverse fields ranging from nanophotonics, chemical imaging and materials
science. However, spectroscopic nanoimaging is still challenged by the limited
acquisition rate of current nano-FTIR technology. Here we combine s-SNOM,
nano-FTIR and synthetic optical holographic (SOH) to achieve infrared
spectroscopic nanoimaging at unprecedented speed (8 spectroscopically resolved
images in 20 min), which we demonstrate with a polymer composite sample. Beyond
being fast, our method promises to enable nanoimaging in the long IR spectral
range, which is covered by IR supercontinuum and synchrotron sources, but not
by current quantum cascade laser technology.
