An oxygen saturation monitor , comprising: a clamp having opposing first and second clamp portions; an array of light sources disposed on the first clamp portion, each light source being switchable between (i) off, (ii) emitting red light, (iii) emitting infrared light; and (iv) emitting both red light and infrared light; an array of light detectors disposed on the second clamp portion facing the array of light sources, wherein each light detector of the array of light detectors is aligned to detect light emitted from a single one of the light sources and each light source is arranged to illuminate only a single one of the light detectors, thereby forming an array of light source / light detector pairs, wherein, for each light source / light detector pair, the light source corresponds to the light detector; and an electronic processor programmed to: control the array of light sources to emit switched red and infrared light by a single active light source (18.1-18.9) of the array of light sources with all other light sources of the array of light sources being off; detect the switched red and infrared light using the light detector (20.1-20.9) of the array of light detectors that is in the light source / light detector pair for the single active light source and is therefore aligned to detect emitted light from the single active light source; and detect ambient light using the light detectors (20.1-20.9) of the array of light detectors other than the light detector that is aligned to detect emitted light from the single active light source. a clamp having opposing first and second clamp portions; an array of light sources disposed on the first clamp portion, each light source being switchable between (i) off, (ii) emitting red light, (iii) emitting infrared light; and (iv) emitting both red light and infrared light; an array of light detectors disposed on the second clamp portion facing the array of light sources, wherein each light detector of the array of light detectors is aligned to detect light emitted from a single one of the light sources and each light source is arranged to illuminate only a single one of the light detectors, thereby forming an array of light source / light detector pairs, wherein, for each light source / light detector pair, the light source corresponds to the light detector; and an electronic processor programmed to: control the array of light sources to emit switched red and infrared light by a single active light source (18.1-18.9) of the array of light sources with all other light sources of the array of light sources being off; detect the switched red and infrared light using the light detector (20.1-20.9) of the array of light detectors that is in the light source / light detector pair for the single active light source and is therefore aligned to detect emitted light from the single active light source; and detect ambient light using the light detectors (20.1-20.9) of the array of light detectors other than the light detector that is aligned to detect emitted light from the single active light source. control the array of light sources to emit switched red and infrared light by a single active light source (18.1-18.9) of the array of light sources with all other light sources of the array of light sources being off; detect the switched red and infrared light using the light detector (20.1-20.9) of the array of light detectors that is in the light source / light detector pair for the single active light source and is therefore aligned to detect emitted light from the single active light source; and detect ambient light using the light detectors (20.1-20.9) of the array of light detectors other than the light detector that is aligned to detect emitted light from the single active light source. <EOS>