Cerebral oximetry using time-gated direct sequence spread spectrum

A method of performing cerebral oximetry comprising:

• emitting light within a first range of wavelengths in response to a first electrical signal;
• emitting light within a second range of wavelengths in response to a second electrical signal;
• detecting at least a portion of the light emitted from a first light source;
• detecting at least a portion of the light emitted from a second light source;
• modulating the first electrical signal and the second electrical signal using a spreading sequence to occupy an electrical bandwidth greater than necessary to send optical signal pulse amplitude information to a photodetector;
• processing a first detection signal from a first photodetector and a second detection signal from a second photodetector with a correlator or a matched filter, wherein each of the processed first and second detection signals indicative of a function of light path time delay;
• and
• filtering the processed first and second detection signals with a time gate based on a desired time of arrival.

A cerebral oximeter comprising:

• first emitting means for emitting light within a first range of wavelengths in response to a first electrical signal;
• second emitting means for emitting light within a second range of wavelengths in response to a second electrical signal;
• a detecting means for detecting at least a portion of the light emitted from the first emitting means and for detecting at least a portion of the light emitted from the second emitting means;
• modulating means for modulating the first electrical signal and the second electrical signal using a spreading sequence to occupy an electrical bandwidth greater than necessary to send optical signal pulse amplitude information to the detecting means;
• a correlating means for determining a detection light signal intensity of a function of a light path time delay based on detected light from the detecting means;
• and
• filtering means configured to filter a first detection light signal intensity from the correlating means and a second detection light signal intensity from the correlating means based on a desired time-of-arrival.