Patent ID: 7190464

Claim:
A method for diagnosing a human condition from a characteristic of tissue in a biological sample, the method comprising: directing broadband light by means of a sensing light path at the biological sample, said sensing light path having an effective light path length; receiving said broadband light reflected from the biological sample by means of said sensing light path; directing said broadband light by means of a reference light path at a reference reflecting device, said reference light path having an effective light path length; receiving said broadband light reflected from said reference reflecting device by means of said reference light path; directing said broadband light reflected from the biological sample and reflected from said reference reflecting device at a first reflecting device by means of a first light path and at a second reflecting device by means of a second light path, said first and second light paths having corresponding effective light path lengths; combining said broadband light reflected from said first reflecting device and reflected from said second reflecting device; modulating said effective light path lengths of said first and second light paths to minimize a difference to within about two coherence lengths of said broadband light, said difference corresponding to the effective light path lengths of said reference light path and said sensing light path; detecting said broadband light resulting from broadband light reflected from said first depth in the biological sample and said broadband light reflected from said reference reflecting device, to generate a signal indicative of an interference of said broadband light reflected from said first depth in the biological sample and said broadband light reflected from said reference reflecting device; determining a first phase from said signal indicative of said interference of said broadband light reflected from said first depth in the biological sample and said broadband light reflected from said reference reflecting device; changing the effective light path length of at least one of said reference light path and said sensing light path to define a second depth; detecting said broadband light resulting from said broadband light reflected from said second depth in the biological sample and said broadband light reflected from said reference reflecting device, to generate a signal indicative of an interference of said broadband light reflected from said second depth in the biological sample and said broadband light reflected from said reference reflecting device; determining a second phase from said signal indicative of said interference of said broadband light reflected from said second depth in the biological sample and said broadband light reflected from said reference reflecting device; determining the characteristic of the biological sample from said first phase and said second phase; and diagnosing a human condition from the characteristic.