The StereoVision system from Boon Edam merges two types of sensing technologies — optical and near infrared light — to monitor the compartment of a revolving security door or portal for piggybacking. The two technologies work together to determine displacement and distance by measuring the time it takes light to travel from the instrument to an object and back, enabling it to accurately tell the difference between two people and one person holding a box or luggage to minimize false rejections. The near infrared light sensor is not affected by sunlight or reflections, which eliminates any environmental impairment of the system at locations near the exterior of buildings.
