Optical parameters and space-bandwidth product optimization in digital holographic microscopy

Area of Science:

• * Optical physics and microscopy
• * Wave optics and holography

Background:

• * Digital holographic microscopy (DHM) relies on precise optical parameter characterization.
• * Conventional microscopy often requires high-quality objectives to maximize space-bandwidth product (SBP).

Purpose of the Study:

• * To mathematically derive key optical parameters for DHM using geometrical and diffraction models.
• * To demonstrate the benefits of out-of-focus hologram recording for increasing field of view and SBP.
• * To derive imaging distance and depth of field (DOF) expressions for various holographic setups.

Main Methods:

• * Geometrical and diffraction-based modeling for optical parameter derivation.
• * Analysis of out-of-focus hologram recording to optimize SBP matching.
• * Derivation of imaging distance considering reference-wave curvature.
• * Investigation of defocus effects on modulation transfer function (MTF) to determine DOF.

Main Results:

• * Out-of-focus recording increases field of view and improves SBP matching, offering a cost-efficient alternative to high-NA objectives.
• * A derived expression for imaging distance accounts for reference-wave curvature, applicable to lensless digital holography.
• * Matched object and reference waves minimize imaging distance, maximizing recoverable SBP.
• * Rectangular apertures yield increased resolution and DOF compared to circular apertures of similar size.

Conclusions:

• * DHM with out-of-focus recording provides a cost-effective method for enhancing SBP and field of view.
• * Lensless digital holography benefits from matched reference waves for greater SBP recovery.
• * Rectangular apertures present a significant advantage in resolution and DOF for lensless imaging systems.