On-speckle suppression in IR digital holography

Area of Science:

• Optics and Photonics
• Digital Holography
• Image Processing

Background:

• Long-infrared (IR) wavelengths are optimal for capturing digital holograms of large, real-world objects.
• Coherent noise in long-IR holograms significantly degrades the quality of numerical and optical reconstructions compared to visible wavelengths.

Purpose of the Study:

• To develop and demonstrate an efficient method for suppressing coherent noise in long-IR digital holograms.
• To improve the quality of numerical reconstructions for large-size objects recorded in the IR spectrum.

Main Methods:

• An optical scanning multi-look approach was employed.
• 3D block matching numerical filtering was utilized in combination with the optical scanning.
• The method was applied to digital holograms of a rotating statuette.

Main Results:

• Efficient suppression of coherent noise in long-IR digital holograms was achieved.
• Near noise-free numerical reconstructions were obtained while preserving object resolution.
• Remarkable contrast enhancement was observed, recovering details obscured by speckle grains.

Conclusions:

• The combined optical scanning multi-look and 3D block matching filtering effectively suppresses coherent noise in long-IR digital holography.
• This technique enables high-quality, high-resolution numerical reconstructions of large objects from IR holograms.
• The method significantly enhances contrast and recovers fine object details lost due to source coherence-induced speckle.