High-resolution rotation-angle measurement of a cylinder using speckle displacement detection

A new method for measuring the rotation angle of a cylinder is described, based on the speckle displacement detection caused by the cylinder surface rotation. It is shown that this method is effective for measuring the small rotation angle with high resolution. The accuracy, sensitivity, and resolution of this method are determined by the speckle size, detector pitch, and magnification of the speckle displacement. The configuration to obtain an accurate, sensitive, stable measuring system is discussed. The usefulness of this method is confirmed by experiments.