Patent ID: 7835013

Claim:
An interferometric detection system comprising: (a) a substrate; (b) a channel formed in the substrate for reception of a fluid sample to be analyzed; (c) a coherent light source for generating a coherent light beam, the light source being positioned to direct the light beam onto the substrate such that the light beam is incident on the channel to thereby generate backscattered light comprising interference fringe patterns; (d) a photodetector for receiving the backscattered light and generating one or more intensity signals that vary as a function of positional shifts in the interference fringe patterns; and (e) at least one signal analyzer for receiving the intensity signals and generating at least one of a signal A and a signal B, and determining therefrom a characteristic property of the fluid sample in the channel, wherein the signal analyzer further comprises a processor programmed to determine a characteristic property of the fluid sample in the channel by performing a method comprising the steps of: (i) determining a value q as a function of the sum of one or more overlapping products of signal A and signal B; (ii) determining a value p as a function of the sum of one or more weighted overlapping products of signal A and signal B; and (iii) calculating the shift between signal A and signal B as a function of p divided by q.