At the same time optical rotation of the particles was realized. The rotation frequency was measured by CCD camera and quadrant photodiode detector (QD).

Experimental results show that this watermark detector has not only the good robustness to Gaussian noise, but also the very strong resistant ability to translation and rotation attacks.

Based on characteristics of optical polarizing, Malus law, and Faraday optical rotation, a long-range displacement detector is realized by same light source and double light route.