Walcutt_N_27November_2017 |
Walcutt_N_27November_2017
Graduate School of Oceanography - OCG 695
27 November, 3:30 PM, Coastal Institute Auditorium
27 November, 3:30 PM, Coastal Institute Auditorium
Assessment of holographic microscopy for quantifying marine particle size and concentration
Achieving micron-scale measurements of marine particles and depth-resolved, ocean-basin coverage in sparse, highly variable oceanic environments persists as a methodological challenge. In situ holography may address this challenge by sampling 100x larger volumes than comparable objective lens-based systems, and is easily deployable on CTD-rosette, flow-through, and autonomous systems. Here, the quantitative capability of a digital in-line holographic microscope to evaluate size and concentration of particles ranging from 5 to 1000 microns in diameter is assessed. Over 500,000 particles are analyzed using a custom image processing pipeline, which allows a precise definition of the three-dimensional volume sampled. Recommendations for correcting the observed sizes and observed concentrations to the true sizes and concentrations are presented. The results of an inter-calibration with two other particle imaging systems, the FlowCam and the Imaging FlowCytobot, provide validation of the accuracy of these methods. Finally, calibrated size, concentration and aspect ratio statistics from CTD-mounted holographic microscope deployments are presented and some results that will guide the next steps of this project are discussed.
Noah Walcutt earned a B.E. in Mechanical Engineering from Vanderbilt University in 2008. He entered the M.S. program at GSO in Spring 2016. His major professor is Melissa Omand.
Achieving micron-scale measurements of marine particles and depth-resolved, ocean-basin coverage in sparse, highly variable oceanic environments persists as a methodological challenge. In situ holography may address this challenge by sampling 100x larger volumes than comparable objective lens-based systems, and is easily deployable on CTD-rosette, flow-through, and autonomous systems. Here, the quantitative capability of a digital in-line holographic microscope to evaluate size and concentration of particles ranging from 5 to 1000 microns in diameter is assessed. Over 500,000 particles are analyzed using a custom image processing pipeline, which allows a precise definition of the three-dimensional volume sampled. Recommendations for correcting the observed sizes and observed concentrations to the true sizes and concentrations are presented. The results of an inter-calibration with two other particle imaging systems, the FlowCam and the Imaging FlowCytobot, provide validation of the accuracy of these methods. Finally, calibrated size, concentration and aspect ratio statistics from CTD-mounted holographic microscope deployments are presented and some results that will guide the next steps of this project are discussed.
Noah Walcutt earned a B.E. in Mechanical Engineering from Vanderbilt University in 2008. He entered the M.S. program at GSO in Spring 2016. His major professor is Melissa Omand.