We present a method for obtaining a position-dependent absorption coefficient from near-field scanning optical transmission microscopy. We show that the optical transmission intensity can be combined with the topography, resulting into an absorption coefficient that simplifies the analysis of different materials within a sample. The method is tested with the dye rhodamine 6G, and we show some analysis in biological samples such as bacteria <i>Klebsiella pneumoniae</i> and <i>Pseudomonas aeruginosa</i>. The calculated absorption coefficient images show important details of the bacteria, in particular for <i>P. aeruginosa</i>, in which membrane vesicles are clearly seen.
© 2003 Optical Society of America
(170.1530) Medical optics and biotechnology : Cell analysis
(170.5810) Medical optics and biotechnology : Scanning microscopy
(180.5810) Microscopy : Scanning microscopy
(300.1030) Spectroscopy : Absorption
Ana M. de Paula, Claudilene R. Chaves, Haroldo B. Silva, and Gerald Weber, "Absorption Coefficient Imaging by Near-Field Scanning Optical Microscopy in Bacteria," Appl. Opt. 42, 3005-3008 (2003)