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Distance measurements by speckle correlation of objective speckle patterns, structured by the illumination
Michael Linde Jakobsen1, Steen Grüner Hanson
1DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, P.O. Box 49, DK-4000, Roskilde, Denmark. mlja@fotonik.dtu.dk
Applied Optics
|July 10, 2012
Summary
Objective speckles from interfering laser beams can measure distance. This method precisely probes object distance with high accuracy, dependent on beam overlap and spot size.
Area of Science:
- Optics
- Metrology
- Surface characterization
Background:
- Objective speckles arise from the interference of light scattered from rough surfaces.
- Speckle patterns contain information about the illumination and scattering conditions.
Purpose of the Study:
- To develop a method for measuring distance using objective speckles.
- To quantify the uncertainty and dependencies of this distance measurement technique.
Main Methods:
- Derivation of the autocovariance function for objective speckle patterns.
- Experimental validation of distance measurement using interfering beams on a rough surface.
Main Results:
- Demonstrated distance probing of objects from 75 mm to 150 mm.
- Achieved measurement uncertainty better than ±0.1% of the full range.
- Uncertainty is inversely proportional to the beam spot size on the object.
Conclusions:
- Objective speckles provide a viable method for precise distance measurement.
- The technique's accuracy is controllable via beam parameters like angle and spot size.
