A guide to human eye safety for designers of consumer products, app note from Renesas. Link here (PDF)
Active Proximity Sensing for Consumer products requires the use of a light-emitting component to illuminate the target object to be detected at some distance from the sensor. Typically, product designers do not want the illumination to interfere with the other functions of the product, or to distract the user during normal use. Therefore, Infrared Light-emitting Diodes (IR-LEDs) are used as the light-emitting components for proximity sensing. To further reduce the user awareness of the proximity function, the IR-LED and the proximity sensor are located under heavily tinted – but, infrared-transmitting – glass. While remaining unaware of any illuminating light source, the consumer indeed is exposed to low-levels of infrared radiation. All consumer products that emit light radiation – whether visible, ultraviolet, or infrared – must adhere to international standards that specify exposure limits for human eye safety.