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Lenticular array for spatial filtering velocimetry of laser speckles from solid surfaces.
Michael L Jakobsen1, Steen G Hanson
1Department of Optics and Plasma Research, Risø National Laboratory, DK-4000 Roskilde, Denmark. michael.linde.jakobsen@risoe.dk
Applied Optics
|September 9, 2004
Summary
This study introduces a low-cost optical sensor for measuring solid structure movement using speckle translation. The system accurately detects in-plane translation and rotation with 1% accuracy at 1.6 mm.
Area of Science:
- Optical Engineering
- Metrology
- Solid Mechanics
Background:
- Speckle translation analysis is crucial for measuring mechanical properties of solid structures.
- Existing methods may lack cost-effectiveness or comprehensive phase information retrieval.
Purpose of the Study:
- To develop and characterize a low-cost optical sensor for detecting speckle translation.
- To enable precise measurement of in-plane translation and rotation of solid structures.
Main Methods:
- Illuminating a nonspecular surface with coherent light.
- Utilizing a lenticular array as a spatial bandpass filter for speckle field dynamics.
- Employing differential photodetectors and a zero-crossing-detection processor.
Main Results:
- The optical design successfully detects speckle translation, providing measures of in-plane translation and rotation.
- Achieved a measurement accuracy of 1% at 1.6-mm translation under constant velocity.
- Demonstrated that relative standard deviation improves with the square root of distance traveled.
Conclusions:
- The developed low-cost optical sensor is effective for measuring mechanical displacements.
- The system's ability to access full phase information enhances measurement precision.
- This technology offers a viable solution for non-contact structural monitoring.