One-Dimensional Translation Measurement of Speckle from Rough Rotating Objects inUltraviolet Illumination

摘要

The experimental measurement of translation in one dimension from near-fieldspeckle produced by rough rotating objects is considered in this report. Rotation rates about single fixed axis are estimated from measured speckle intensity pattern translation values. The feasibility of translation measurements made by cross-correlation technique in a single dimension is demonstrated. A technique for image enhancement is also demonstrated. The speckle pattern images can be enhanced so that intensity distributions meet near-ideal distributions and contrast values. Speckle is produced experimentally by small (2.5-, 4.0-, 5.0-mm diameter) spherical objects with aluminum paint surfaces in coherent ultraviolet illumination. The measurements are made from imagery taken before and after object angular displacement, rather than from imagery taken from objects revolving in real time. Signal to noise ratios are compared for the direct evaluation of the cross correlation function and for the evaluation of the normalized form of the cross-correlation function as well as for correlation functions for enhanced and unenhanced imagery.