🚀 go-pugleaf

From Wolfbeis, Otto S. "Fiber Optic Chemical Sensors and Biosensors"
Volume 2. CRC Press May 1991.

        A pulsatile arterial bed (such as a patients earlobe or toe)
        is sandwiched between a pair of LEDs (emitting 660 and 925nm)
        A fiber bundle which sends transmitted light of both wavelengths
        to a photodetector. The intensity of light eaching the photodiode
        is determined by the pigmentation and thickness of the skin and
        the absorption of venous and arterial blood in the tissue. The 
        absorbance of the skin and venous blood is constant; that of 
        the arterial blood changes because of pulsatile blood flow.

I've got a coupla questions:
 I went into the hospital for a procedure and had an oximeter taped to my
right index finger, afterwards I asked the doctor if I could have the
sensor
It had only ONE LED and Phototransistor, Not two. From this they got not
only
my pulse but blood oxygen level, too.
The book referenced above is not available to me, is too expensive ($200!),
and doesn't cover the one LED method anyway. Can anyone shed some light
(other than 660 and 925nm, :-)   on this. 
Jeff