Common-path digital holographic microscopy based on a volume holographic grating for quantitative phase imaging

Area of Science:

• Optical microscopy
• Holography
• Biophysics

Background:

• Digital holographic microscopy (DHM) is a quantitative phase imaging (QPI) technique for enhanced contrast.
• Common-path configurations improve DHM stability, but diffraction gratings cause power loss.
• Volume holographic gratings (VHGs) offer a single diffraction order, reducing power loss.

Purpose of the Study:

• To propose and demonstrate a VHG in common-path DHM (VHG-DHM) for improved QPI.
• To enhance signal-to-noise ratio and reduce stray light noise.
• To enable precise thickness measurements and high-contrast cell imaging.

Main Methods:

• Implementation of a VHG in a common-path DHM setup.
• Utilizing Bragg-matched wavelength degeneracy for cell observation at 632.8 nm.
• Fabrication of VHG for controlled beam separation angle.

Main Results:

• VHG-DHM demonstrated improved signal-to-noise ratio compared to conventional DHM.
• Reduced image noise due to VHG's high angular selectivity.
• Accurate thickness measurements (100-350 nm) and high-contrast QPI images of human lung cancer cells.

Conclusions:

• VHG integration offers a significant advancement for common-path DHM.
• The VHG-DHM system provides a stable, high-performance platform for QPI.
• This technique is valuable for biological imaging and metrology.