Off-axis digital holographic microscopy with LED illumination based on polarization filtering

Area of Science:

• Optics and Photonics
• Microscopy
• Holography

Background:

• Digital holographic microscopy (DHM) is a powerful technique for 3D imaging.
• Traditional DHM setups can be complex and sensitive to environmental vibrations.
• Improving phase stability and reducing noise are critical for high-resolution holographic imaging.

Purpose of the Study:

• To propose and validate a reflection mode digital holographic microscope.
• To enhance imaging performance using LED illumination and off-axis interferometry.
• To achieve reduced phase noise and faster recording times.

Main Methods:

• The proposed setup integrates a Linnik interferometer with a grating-based 4f imaging unit.
• Coaxial object and reference waves are diffracted by a grating, with polarization filtering selecting specific orders.
• Holograms are acquired in a one-shot, off-axis configuration for millisecond-scale recording.

Main Results:

• The system successfully imaged nanostructured substrates.
• Phase noise was reduced by approximately 68% compared to a He-Ne laser-based system.
• Uniform hologram contrast was achieved across the field of view.

Conclusions:

• The developed reflection mode DHM offers improved phase stability and reduced noise.
• The use of LED illumination and off-axis interferometry is effective for high-performance holographic microscopy.
• This technique shows promise for advanced imaging of micro- and nanostructures.