NEAR NORMAL INCIDENCE OPTICAL ASSAYING METHOD AND SYSTEM HAVING WAVELENGTH AND ANGLE SENSITIVITY

摘要

A method and system (10) for optically assaying a substance (140) in a sample (150) using a sensing system having a diffraction grating sensor (250). A system and method are described that expose the sensor with a light beam at near normal angles of incidence and quantitatively measure the concentration of targeted substance by determining the angular separation between resulting anomaly angles ( theta 1, theta 2). The present invention also contemplates a system and method that quantitatively measure the concentration of targeted substance by determining the wavelength separation between resulting anomaly wavelengths. Advantages of the present invention include increased sensitivity and less susceptibility to system drifts due to mechanical motion and thermal changes than conventional diffraction grating sensors.