Wavelength-scanning surface plasmon resonance imaging

A new surface plasmon resonance (SPR) imaging technique was proposed. After measurements were conducted at varying wavelengths, the wavelength affording the minimum brightness (SPR wavelength) was determined at each pixel of the image. A two-dimensional map of the SPR wavelength could be converted to a thickness profile by use of a nonlinear calibration curve, which was obtained by Fresnel calculation. An array of protein thin layers on a gold film was evaluated in air to present the layersʹ surface structure in nanometer scale.