Nanometric displacement measurement using phase singularities in Laguerre-Gauss transform of speckle pattern

摘要

Contrary to the common belief of optical metrology, where the phase singularities are considered as obstacles in phase unwrapping, we propose a new technique that makes use of phase singularities in the complex signal representation of a speckle pattern as indicators of local speckle displacements. The complex signal representation is generated by Laguerre-Gauss filtering the dynamic speckle patterns. Experimental results are presented that demonstrate the validity and the performance of the proposed optical vortex metrology for lateral speckle displacement measurement with a large dynamic range.