Importance

Loading Importance Indicators...

Abstract

A method of exposing a patient's extremity to light of two wavelengths and detecting the absorbance of the extremity at each of the wavelengths is provided comprising the steps of: (a) generating pulses of light having the first wavelength at a first pulse frequency; (b) generating pulses of light having the second wavelength at a second pulse frequency; (c) exposing the extremity to the first and second pulses; (d) producing an electrical signal corresponding to the total amount of light transmitted through the extremity; (e) separating the electrical signal produced in step (d) into a first amplitude-modulated electrical signal at the first pulse frequency and a second amplitude-modulated electrical signal at the second pulse frequency; and (f) demodulating the first and second amplitude-modulated electrical signals to produce a first signal corresponding to the amount of light transmitted through the extremity at the first wavelength and a second signal corresponding to the amount of light transmitted through the extremity at the second wavelength. The method allows the extremity to be exposed to the two wavelengths in the presence of ambient light and essentially eliminates interference problems caused by 60-cycle power sources. Apparatus for practicing the method is also disclosed.

Loading the Abstract Image...

First Claim