Analysis of light scattering from human breast tissue using a custom dual-optical scanning near-field optical microscope

In this paper we introduce a custom scanning near-field optical microscope (SNOM) that simultaneously collects reflection and transmission near-field images along with topography. This dual-optical SNOM uses a bent probe, which allows for axial reflection imaging, accurate surface scanning, and easy identification of topographic artifacts. Using this novel dual-optical SNOM, we image desiccated and non-desiccated human breast epithelial tissue. By comparing the simultaneous SNOM images, we isolate the effects of tissue morphology and variations in refractive indices on the forward- and back-scattering of light from the tissue. We find that the reduction in back-scattering from tissue, relative to the glass slide, is caused by dense packing of the scattering sites in the cytoplasm (morphology) in the desiccated tissue and a thin-film of water adhering to the glass slide (refractive index) in the non-desiccated tissue sample. Our work demonstrates the potential of our customized dual-optical SNOM system for label-free tissue diagnostics. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)