Does the structure of light influence the speckle size?

Area of Science:

• Optics and Photonics
• Laser Physics
• Wave Phenomena

Background:

• Speckle patterns form when lasers interact with rough surfaces or diffusive media.
• Speckle size is well-defined for homogeneous illumination but not for structured light.
• Structured light beams exhibit non-homogeneous intensity and phase distributions.

Purpose of the Study:

• To propose and demonstrate a method for measuring the mean speckle size of structured light beams.
• To provide mathematical expressions relating speckle size to generalized spot size definitions.
• To compare speckle size from structured light with that from homogeneous illumination.

Main Methods:

• Utilized Hermite- and Laguerre-Gaussian light modes.
• Applied homogeneous illumination assumptions for speckle size measurement.
• Derived mathematical expressions for speckle size and generalized spot size.

Main Results:

• Demonstrated that mean speckle size for structured light can be measured assuming homogeneous illumination.
• Provided new mathematical expressions linking speckle size to generalized spot size.
• Showed that mean speckle size is nearly identical for structured light and homogeneous wave fronts.

Conclusions:

• Speckle size measurement is feasible for structured light using homogeneous illumination principles.
• The findings reveal a fundamental property of speckle applicable to various laser-based technologies.
• This research may enable novel applications leveraging speckle phenomena.