Evanescent field scanning optical microscopy

Abstract

The authors propose an alternative method for high resolution optical microscopy -Evanescent Field Scanning Optical Microscopy (EFSOM) which eliminates implementation of the scanning tip compare to classical NSOM technique. The approach involves scanning a sample in the evanescent-field of a prism generated using total internal reflection (TIR) and recording the reflected power as a function of position. The reflection pattern of the wave is collected and processed, using comparative differentiation. The extracted information is processed further to eliminate any distortions. The system is not limited by diffraction and resolution primarily depends on the characteristics of the photo-detector and scanning velocity. Implementation of thin silver layer and coupling of incident radiation into Surface Plasmons Polaritons (SPP) improves system sensitivity and reduces photo detector dynamic range requirements.