Compact microscopy systems with non-conventional optical techniques
Date
2018
Authors
Kamal, Tahseen
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Abstract
This work has been motivated by global efforts to decentralize
high performance imaging systems through frugal engineering and
expansion of 3D fabrication technologies. Typically, high
resolution imaging systems are confined in clinical or laboratory
environment due to the limited means of producing optical lenses
on the demand.
The use of lenses is an essential mean to achieve high resolution
imaging, but conventional optical lenses are made using either
polished glass or molded plastics. Both are suited for highly
skilled craftsmen or factory level production. In the first part
of this work, alternative low-cost lens-making process for
generating high quality optical lenses with minimal operator
training have been discussed. We evoked the use of liquid
droplets to make lenses. This unconventional method relies on
interfacial forces to generate curved droplets that if solidified
can become convex-shaped lenses. To achieve this, we studied the
droplet behaviour (Rayleigh-Plateau phenomenon) before creating a
set of 3D printed tools to generate droplets. We measured and
characterized the fabrication techniques to ensure reliability in
lens fabrication on- demand at high throughput. Compact imaging
requires a compact optical system and computing unit. So, in the
next part of this work, we engineered a deconstructed microscope
system for field-portable imaging.
Still a core limitation of all optical lenses is the physical
size of lens aperture – which limits their resolution
performance, and optical aberrations – that limit their imaging
quality performance. In the next part of this work, we
investigated use of computational optics-based optimization
approaches to conduct in situ characterization
of aberrations that can be digitally removed. The computational
approach we have used in this work is known as Fourier
Ptychography (FP). It is an emerging computational microscopic
technique that combines the use of synthetic aperture and
iterative optimization algorithms, offering increased resolution,
at full field-of-view (FOV) and aberration-removal. In using FP
techniques, we have shown measurements of optical distortions
from different lenses made from droplets only. We also,
investigated the limitations of FP in aberration recovery on
moldless lenses.
In conclusion, this work presents new opportunities to engineer
high resolution imaging system using modern 3D printing
approaches. Our successful demonstration of FP techniques on
moldless lenses will usher new additional applications in digital
pathology or low-cost mobile health.
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Keywords
droplet lens, lenses, manufacturing, mobile health, computational, compact,, portable, low-cost, 3D printed, passive droplet
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