Sensor device and use of a sensor device

摘要

The sensor device (1) has an optical transmitter, a reflector (14) and a receipt unit, where the optical transmitter sends light having specific optical characteristics. The reflector forms an optically active modulation layer, and an optically active modulation layer is arranged before the reflector, which changes light back reflecting specific optical characteristics, particularly polarization or wavelength changing at the receipt unit over the reflector. The reflector is arranged at an object. An independent claim is included for an optical key with a non-volatile display.