Researchers at Korea Advanced Institute of Technology (KAIST) collaborated with scientists from Singapore (National University of Singapore and Singapore Management University) to develop a prototype SweepLED device. The gadget turns an ordinary smartphone into a highly accurate detector of hidden surveillance cameras (spy cameras), solving the problems of false alarms and human error when inspecting hotel rooms, fitting rooms or rental properties.
The magnetic attachment costs less than $7 (about 600 rubles) and is installed around the camera unit on the back of the smartphone. It uses LEDs to alternately illuminate suspicious objects from different angles. The highlights of polished metal, mirrors, or smooth plastic can move erratically or disappear completely as the angle of light changes. At the same time, the camera’s complex internal optics (aperture, lens, and light sensor) create characteristic patterns of optical refraction. Short videos recorded by a smartphone are processed by a local neural network model that is trained to recognize specific deformations of the lens flare. Scanning a suspicious item takes less than five seconds.
Because the method relies solely on the optical physics of glass refraction, it can find hidden cameras even if they are completely disabled or not transmitting radio signals over Wi-Fi. In a test of 30 common indoor items (charging stands, wall clocks, table clocks, sensors, remote controls), the system’s detection accuracy reached 93.9%. The authors plan to reduce the size of the nozzle and improve the application in order to release the solution as an affordable commercial accessory.
