Optimisation of a Holographic Microscope for Microbial Study

Abstract

Background: Tracking of microbial organisms over a volume requires images at multiple focal planes along the orthogonal direction. With most conventional microscopes, this requires repeated readjustments; using Digital Holographic Microscopy (DHM), it is possible to use a set of interference patterns to reconstruct at various distances, thereby creating a 3D stack based off a single image. Methods: We used an off-axis Mach-Zehnder DHM for imaging and tracking bacterial movement. We describe the algorithm employed for tracking, as well as our improvement of trackability by testing differences in image contrast with the use of Quantum Dots. Results: We show that the use of Quantum Dots resulted in an increase in contrast of approximately 11%. Conclusion: We suggest this as a method of increasing resolvability of individual microbes. With a more compact design, the microscope will be applicable in various fields, and can be used remotely for studies of microbial organisms.