Resolution optimization of an off-axis lensless digital holographic microscope

Area of Science:

• Astrobiology
• Microscopy
• Optical Engineering

Background:

• Detecting extraterrestrial cellular life requires high-resolution, compact, and robust microscopes.
• Space exploration missions to ocean moons necessitate advanced imaging capabilities.

Purpose of the Study:

• To optimize the resolution of a compact off-axis lensless digital holographic microscope (DHM).
• To identify optimal configurations for high-resolution imaging in extreme environments.

Main Methods:

• Analysis of resolution regimes in lensless DHM configurations.
• Experimental validation using a 2kx2k pixel array DHM in a high-magnification regime.
• Application of standard aberration correction software.

Main Results:

• Identified two optimal high-resolution regimes: low-magnification (sample near detector) and high-magnification (sample near source).
• Achieved a spatial resolution of ~0.95 µm, significantly smaller than the pixel size (5.5 µm).
• Demonstrated that resolution improves with detector array size in the high-magnification regime.

Conclusions:

• Lensless DHM can achieve near wavelength-scale resolution with larger detector arrays.
• The optimized DHM design is suitable for detecting cellular life in extraterrestrial extreme environments.
• Sub-micrometer resolution is achievable with compact, lensless holographic microscopy.