Nanoprecision algorithm for surface plasmon resonance determination from images with low contrast for improved sensor resolution

A forward-projection algorithm based on Radon transform for two-dimensional surface plasmon imaging was devised to achieve nanoscale precision in determining the surface plasmon signal. A diverging laser beam at the chosen frequency was used to overcome the angular scanning in the well-known Kretschmann configuration. Multichannel sensing with improved resolution was realized. The technique was also used to find the lateral resolution of the sensor using a patterned layer of 40-nm thick SiO₂ layer on top of the metallic surface. As a surface plasmon resonance signal detector, the use of the proposed Radon transform algorithm shows nanoprecision accuracy in cases of single and multichannel sensing. The method also provides the filtered output of the signal without any extra modification and therefore, it is nonsensitive to noise.