A method and device for capturing speckles are described. A highly coherent light emitted from a light source is used to illuminate a surface and produces scattered lights. The scattered lights pass through a light restrictive element and the diffracted lights produced by this restrictive element interfere with one another to generate a speckle pattern. An image sensor is then used to pick up the speckle pattern to form a speckle image. Therefore, the effects of diffraction and interference and a light restrictive element to enlarge the speckle size and reduce the variation of the speckle pattern during the movement of the imaging device are utilized, so that the speckle pattern can be clearly identified in the image. As a result, the method and device for capturing speckles are fairly stable and sensitive.