Application of fiber specklegram sensor to fine angular alignment

Experimentation of fiber specklegram sensor (FSS) as applied to fine angular alignment is presented. The objective is to exploit the spatial information contents (i.e., fiber speckle field) for sensing. The results shown that FSS is highly sensitive to fiber perturbation. As applied to fine angular alignment, two sensing fibers are tightly glued on a plastic rod. By bending the plastic rod, high angular measurement with bending direction can be obtained. The sensitivity measurement is shown to be as high as 0.02°, using a 0.3 numerical aperture (NA) silicate fiber. The sensitivity can be further improved if one uses higher NA fibers.