Abstract: A system for externally monitoring the angular rotation rate of a spin rinse dryer chamber in a semiconductor fabrication facility. The system includes a spin rinse dryer comprised of a dryer housing and a chamber wall that is capable of rotating within the housing. The chamber wall defines a chamber suitable for receiving a designated wafer carrier. The dryer further includes a chamber door hinged to the housing for enclosing the chamber. The spin rinse dryer is configured to rotate the chamber when activated. A detection apparatus of the system is positioned externally to the dryer housing in proximity to the chamber. The detection apparatus is adapted to detect the angular rotation rate of a detectable marker affixed to an exterior wall of the designated wafer carrier when the designated wafer carrier is placed in the chamber and the spin rinse dryer is activated.