專利摘要：
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 field of view of the sensor, when the speckle capturing device has a relative motion with respect to the surface, the speckle only move on the image but the shape and the intensity are almost keep constant, that is favorable for high accuracy optical pattern recognition and positioning.