Patent ID: 7031508

Claim:
A method of quantifying data to determine possible presence of a target analyte in a specimen in which a sample of said target analyte is placed upon a membrane having a spot region that, in the presence of said target analyte, changes at least one optical characteristic relative to surrounding regions of said membrane, the method comprising the following steps: (a) alternately and periodically illuminating said surrounding regions of said membrane and said spot region with light from a light source, said light traversing an air path undeflected by any planar optical element disposed between said light source and said membrane; (b) detecting light reflected from said spot region and from said surround regions of said membrane with light detectors disposed so as to reduce skew error due to irregularities in topography of said membrane, reflected said light traversing an air path undeflected by any planar optical element disposed between said light detectors and said membrane; (c) signal processing output from said light detectors to discern from optical characteristic information of said spot region relative to optical characteristic information of said surrounding regions of said membrane presence of said target analyte; and (d) providing an output signal commensurate with an output from said signal processing.