How does Meditech oximeters operate

How does Meditech oximeters operate?
The oximeter works according to Lambert Beer Law,
 
Our oximeters omits a near-infrared pulse (a 660nm ray and 940nm near-infrared ray). The light passes through the skin, "hits" red blood cells, and is partially absorbed. The part which isn't absorbed is picked up by the photoelectric sensor, and being analyzed. The analysis is calculated according to the haemoglobin (R Hb) and Oxyhemoglobin (02 Hb) reflectance factor. Reflectance factor, is an index that shows the exact amount and length of light that a substance will absorb, when it is being "hit" by a certain wavelength of light.