Patent ID: 7327445
Filing Date: 2008-02-05
Classification: G01N

Abstract:
1. Apparatus for measuring the refractive index of an analyte, the apparatus comprising: an optical source capable of providing an input beam of optical radiation at a wavelength λ; a prism having a surface capable of receiving and internally reflecting the input beam within the prism to provide an output beam; a metallic layer on the surface of the prism, wherein a sensing interface of the metallic layer facing away from the surface of the prism is in contact with the analyte, wherein the sensing interface supports propagation of a surface plasmon wave, wherein the metallic layer has a complex refractive index n+jκ, wherein a critical thickness d and wherein a thickness d of the metallic layer is selected such that 0.5 d cr ≦d≦1.5 d cr wherein, n is the real part of the complex refractive index and jκ is the imaginary part of the complex refractive index; a detection system capable of receiving the output beam and providing a measurement of at least one non-specular reflection parameter of the output beam, wherein the non-specular reflection parameter depends in part on a detuning from a surface plasmon wave resonance condition; a processor capable of determining a refractive index of the analyte from the measured non-specular reflection parameter.