Laser speckles produced by a diffuse object under illumination from a multimode optical fiber: an experimental study.

Area of Science:

• Optics
• Photonics
• Experimental Physics

Background:

• Speckle patterns are formed by coherent light scattering from diffuse surfaces.
• Previous theoretical work (J. Opt. Soc. Am. A 2, 1282 (1985)) predicted relationships for speckle size and displacement.
• Understanding speckle behavior is crucial for applications in imaging and metrology.

Purpose of the Study:

• To experimentally validate the theory of speckle size and displacement from diffuse objects illuminated by multimode optical fibers.
• To confirm that mean speckle size at the fiber exit can be inferred from observations at an image plane.
• To demonstrate a simpler method for calculating speckle displacement using multimode fiber illumination.

Main Methods:

• Experimental setup involving a diffuse object illuminated by a multimode optical fiber.
• Measurement of speckle pattern characteristics (size and displacement) at an observation plane.
• Comparison of experimental data with theoretical predictions.

Main Results:

• Experimental results demonstrated good agreement with the established theory.
• Successfully verified that mean speckle size at the fiber exit face can be determined from measurements at the observation plane.
• Identified a simpler relation for speckle displacement compared to conventional methods using Gaussian laser beams.

Conclusions:

• The experimental investigation supports the theoretical framework for speckle phenomena with multimode optical fiber illumination.
• The study confirms a practical method for determining speckle size and offers a simplified approach for displacement analysis.
• This research highlights the advantages of multimode optical fibers for speckle-related measurements, offering a more straightforward alternative to laser-based techniques.