An image invariant optical speckle capturing device and method. A highly coherent light is used to illuminate a surface and is scattered by the surface, and is captured from the direction with a ±10° from the angle of specular reflection. A light restrictive module is designed to confine the angular...http://www.google.de/patents/US7715016?utm_source=gb-gplus-sharePatent US7715016 - Image invariant optical speckle capturing device and method
