Polarization-interferometry-based wavelength-interrogation surface plasmon resonance imager for analysis of microarrays.

Polarization interferometry (PI) techniques, which are able to improve surface plasmon resonance (SPR) sensing performance and reduce restrictions on allowable parameters of SPR-supporting metal films, have been experimentally realized only in SPR sensors using monochromatic light as a source. Wavelength-interrogation SPR sensors modulated by PI techniques have not been reported due to the wavelength-sensitive characterization of PI phase compensators. In this work we develop a specially designed rhombic prism for phase compensating which is totally insensitive to wavelength. For the first time we successfully apply PI technique to a wavelength-interrogation SPR imager. This imager is able to offer two-dimensional imaging of the whole array plane. As a result of PI modulation, resolutions of 1.3×10(-6) refractive index unit (RIU) under the normal condition and 3.9×10(-7) RIU under a more time-consuming condition are acquired. The application of this imager was demonstrated by reading microarrays for identification of bacteria, and SPR results were confirmed by means of fluorescence imaging.