Pulse oximetry uses light to work out oxygen saturation. Light is emitted from light sources which goes across the pulse oximeter probe and reaches the light detector.
An oximeter probe is bandage-like probe, it will be attached to your finger to measure the amount of oxygen in your blood. Most pulse oximetry probes are of clip-on style, similar to an old-fashioned wooden clothes pin with springs. The probe measures the percentage of oxygenated hemoglobin using both red (visible) and infrared (invisible) types of light. These light beams are projected through thin, vascular tissue from one side of the probe to a photo detector on the opposite side of the probe’s clip.