When
Where
Title
Applications of a New Architecture for Digital Holographic Microscopy
Abstract
Digital holographic microscopy (DHM) records the full optical wavefield transmitted through a sample, enabling volumetric, quantitative measurements of both amplitude and phase without mechanical scanning or fluorescent labeling. However, conventional DHM instruments based on the Mach–Zehnder interferometer suffer from a fundamental limitation: the object and reference beams travel separate paths, making the instrument sensitive to vibration, thermal drift, and mechanical disturbance. This dissertation introduces a common-mode off-axis DHM architecture in which both beams co-propagate through a shared optical system, providing inherent rejection of environmental disturbances and a substantially simpler, more robust instrument design.
Three instruments built on this architecture demonstrate its versatility across a wide range of applications and operating conditions. The first is a portable field DHM designed for in situ characterization of bacterial motility in extreme environments. The instrument is fully self-contained — 180 mm × 300 mm × 135 mm, battery-powered, with onboard computing — and was deployed to subsurface hypersaline brine pools at the Boulby Underground Research Laboratory in the UK, where three-dimensional bacterial swimming trajectories were observed and reconstructed with no sample manipulation between extraction and measurement. The second instrument extends the architecture to the short-wave infrared (λ = 1.55 µm) for quantitative phase and amplitude characterization of metasurface optical elements, including scalar vortex coronagraph masks and vector Zernike wavefront-sensing masks used in high-contrast astronomical instrumentation. The third instrument achieves diffraction-limited spatial resolution (350 nm) by incorporating high numerical aperture microscope objectives (NA = 0.9) within a chevron mirror assembly that preserves the common-mode stability of the design, enabling precise phase metrology of coronagraphic focal plane masks validated against independent profilometer measurements.
Together, these three instruments demonstrate that a single optical architecture, by virtue of its robustness and adaptability, can serve as the foundation for DHM systems spanning extreme- environment field biology, infrared optical metrology, and visible-wavelength diffraction-limited microscopy — application domains that have not previously been addressed by a unified instrument design.
Please email Jini at jini@optics.arizona.edu or James at jkwallace@arizona.edu for a Zoom link.