Open AccessMeasuring vibrational motion from a moving platform using speckle field detection
Author(s) -
Brandon Redding,
Allen Davis
Publication year - 2017
Publication title -
applied optics
Language(s) - English
Resource type - Journals
ISSN - 0003-6935
DOI - 10.1364/ao.56.002542
Subject(s) - speckle pattern , optics , holography , speckle noise , laser doppler vibrometer , electronic speckle pattern interferometry , sensitivity (control systems) , laser , physics , computer science , laser beams , electronic engineering , engineering
We investigate the ability of a holographic laser vibrometer to mitigate noise introduced when operating on a moving platform or when measuring a moving target. This motion introduces a fundamental limitation on the measurement sensitivity due to the time-varying speckle pattern produced as the illumination beam scans across the target surface. In addition, since existing systems record the phase of only a single speckle grain, speckle fading imposes a limit on the coherent processing interval and thus the frequency resolution of these measurements. In this work, we show that by measuring N speckle grains in parallel using holographic detection, we are able to provide a N 1/2 improvement in the system sensitivity while simultaneously overcoming the limitations on the coherent processing interval imposed by speckle fading. The ability to perform sensitive vibrational measurements of a moving target or from a moving platform could dramatically increase the applications available to laser vibrometry.