Patent ID: 7327463
Filing Date: 2008-02-05
Classification: A61B,G01B

Abstract:
1. A method for determining a characteristic of an analyte in a biological sample, the method comprising: directing broadband light by means of a sensing light path at the biological sample, at a target depth defined by said sensing light path and a reference light path; receiving said broadband light reflected from the biological sample by means of said sensing light path; directing said broadband light by means or said reference light path at a fixed reflecting device; receiving said broadband light reflected from said fixed reflecting device by means of said reference light path; modulating at about a distance of a center wavelength of said broadband light an effective light path length of at least one of said reference light path and said sensing light path with respect to said target depth; detecting said broadband light resulting from said broadband light reflected from said target depth in the biological sample and said broadband light reflected from said fixed reflecting device, to generate a signal indicative of an interference of said broadband light reflected from said target depth in the biological sample and said broadband light reflected from said fixed reflecting device, said signal having a phase component and an amplitude component, said amplitude component comprises an intensity measurement at said target depth; wherein said effective light path length of at least one of said reference light path and said sensing light path is modulated such that said phase component of said signal is sinusoidal and its magnitude generally proportional to said intensity measurement at said target depth; changing said effective light path length of at least one of said reference light path and said sensing light path to define an other target depth, said other target depth is at a distance of about at least a coherence length of said broadband light from said target depth; modulating at about a distance of the center wavelength of said broadband light said effective light path length of at least one of said reference light path and said sensing light path with respect to said other target depth; detecting said broadband light resulting from said broadband light reflected from said other target depth in the biological sample and said broadband light reflected from said fixed reflecting device, to generate an other signal indicative of an interference of said broadband light reflected from said other target depth in the biological sample and said broadband light reflected from said fixed reflecting device for said other target depth, said other signal having a phase component and an amplitude component, said amplitude component comprises an intensity measurement at said other target depth; wherein said effective light path length of at least one of said reference light path and said sensing light path is modulated such that said phase component of said other signal is sinusoidal and its magnitude generally proportional to said intensity measurement at said other target depth; determining the characteristic of the analyte in the biological sample from variations in said intensity measurements; and diagnosing a human condition from the characteristic.