Terahertz near-field microscopy based on a collection mode detector

We report on the development of a collection mode near-field probe for the terahertz spectral range. The near-field detector is based on an aperture type probe with dimensions of 30x30 mum(2). The collection mode technique provides higher sensitivity and higher resolution than the similar illumination mode approach. Spatial resolution better than 40 mum is demonstrated for a broad spectrum of 300-600 mum, which equals to lambda /15 for the longest wavelength. The observed resolution is determined by the size of the probe aperture. (C) 2000 American Institute of Physics. [S0003-6951(00)02848-5].