Patent ID: 7184148

Claim:
A method for diagnosing a human condition from 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 of said reference light path at a reflecting device; receiving said broadband light reflected from said 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 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 reflecting device, wherein said signal is a product of a cosine function; determining a phase component that is an argument of the cosine function; determining a change in the phase component angle of said signal resulting from a change of said effective light path length that is itself induced by a change of a property of the biological sample; determining a variation in an index of refraction from said change in the phase component of said signal; determining the characteristic of the analyte in the biological sample from said variation in said index of refraction; and diagnosing a human condition from the characteristic.