 Optical turnstiles operate much like regular mechanical turnstiles, except that they rely primarily on electronic (infrared) beams, and audible/visual interfaces to control entry.Rather than physically restraining a person, the optical turnstile uses sounds and lights to alert others to attempted entry by unauthorized individuals.The advent of the Americans with Disabilities Act (ADA) drove optical turnstile development because physical barriers for access were no longer legal for public access due to the fact that persons in wheelchairs or with other disabilities could not use them as access points.