Imaging and local infrared spectroscopy with a near field optical microscope

We present the first images and the first spectrum obtained with a home-built near field optical microscope in the mid-infrared range. Images of silica patterns (with a given height of 100 nm) deposited on a silicon wafer have been obtained with two intense infrared light sources: a cascade arc and the free electron laser CLIO. For the time being, the spatial resolution is of the order of λ/4 (namely one micron). Furthermore, by stepping the CLIO laser wavelength through the infrared band of interest, the same instrument has permitted to acquire, in the near field regime, the spectrum of a photosensitive resin (thickness ≈ 600 nm) deposited on a silicon wafer. The spectral resolution is of the order of a few wavenumbers.