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Title: Detectability of unresolved particles in off-axis digital holographic microscopy
Off-axis digital holographic microscopy (DHM) provides both amplitude and phase images, and so it may be used for label-free 3D tracking of micro- and nano-sized particles of different compositions, including biological cells, strongly absorbing particles, and strongly scattering particles. Contrast is provided by differences in either the real or imaginary parts of the refractive index (phase contrast and absorption) and/or by scattering. While numerous studies have focused on phase contrast and improving resolution in DHM, particularly axial resolution, absent have been studies quantifying the limits of detection for unresolved particles. This limit has important implications for microbial detection, including in life-detection missions for space flight. Here we examine the limits of detection of nanosized particles as a function of particle optical properties, microscope optics (including camera well depth and substrate), and data processing techniques and find that DHM provides contrast in both amplitude and phase for unresolved spheres, in rough agreement with Mie theory scattering cross-sections. Amplitude reconstructions are more useful than phase for low-index spheres and should not be neglected in DHM analysis.  more » « less
Award ID(s):
1828793
PAR ID:
10490069
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
Optical Society of America
Date Published:
Journal Name:
Applied Optics
Volume:
63
Issue:
7
ISSN:
1559-128X; APOPAI
Format(s):
Medium: X Size: Article No. B114
Size(s):
Article No. B114
Sponsoring Org:
National Science Foundation
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