Speckle size of light scattered from 3D rough objects

Area of Science:

• Optics and Photonics
• Electromagnetics
• Scattering Theory

Background:

• Speckle patterns arise from the interference of scattered waves from rough surfaces.
• Understanding speckle statistics is crucial for applications like remote sensing and imaging.
• Previous studies often focused on specific geometries or simplified models.

Purpose of the Study:

• To derive the far-zone speckle field and spatial correlation function for arbitrarily shaped conducting rough objects.
• To establish relationships between speckle size and object/illumination parameters.
• To provide specific expressions for speckle sizes from common geometric shapes (spheres, cylinders, cones).

Main Methods:

• Utilizing the scalar Helmholtz integral relation.
• Employing coordinate system transformations.
• Analyzing the spatial correlation function of speckle intensity.

Main Results:

• Derived expressions for the far-zone speckle field and its spatial correlation.
• Established that speckle size is proportional to incident wavelength and object-to-observation plane distance.
• Demonstrated inverse proportionality between speckle size and the maximal illuminated object dimension.
• Showed that speckle shape varies with object geometry.

Conclusions:

• The derived speckle size relationships are applicable to various conducting rough objects.
• Findings are valuable for statistical analysis of speckle from complex surfaces.
• This research supports advancements in speckle imaging for target detection and identification.