Subwavelength resolution far-infrared microscopy.

The technique of scanned evanescent wave imaging can be used to obtain microscopic resolution well below the illumination wavelength. This paper describes the first application of this method to imaging in the far infrared using the 118.8-μm emission of an optically pumped methanol vapor laser. Resolution down to 30 μm has been demonstrated. Limitations set by available signal power are discussed.