Structured-Illumination Microscale Particle-Image Velocimetry
Abstract
The goal of this work is to develop a new particle velocimetry method, structured-illumination microscale PIV (SIµPIV), that exploits structured-illumination microscopy (SIM) approaches originally developed to Òoptically sectionÓ biological samples in fluorescence microscopy. Structured-illumination microscopy will be used to image steady Poiseuille flow through a microchannel, and to obtain images of only the particles in the focal plane, while rejecting the out-of-focus particles. These SIM images will then be processed as ÒstandardÓ microscale particle-image velocimetry (µPIV) images to obtain two-dimensional-two-component (2D-2C) velocity data over a slice of the flow with a thickness comparable to the depth of focus of the imaging system (determined by the microscope objective), much less than the depth of correlation, which is the current spatial resolution of µPIV. The SIM approaches that will be evaluated here reconstruct a single SIM image from just two ÒrawÓ images separated by a small time interval, suggesting that a single SIµPIV velocity field could be acquired from four raw images, where SIM images A and B are reconstructed from images #1 and #2, and images #3 and #4, respectively. The research objectives of this project are to: À Evaluate and implement recent structured-illumination microscopy (SIM) methods that require only two images, such as double-exposure SIM and HiLo microscopy À Use SIM techniques to visualize fluorescent, neutrally buoyant a < 1 µm tracer particles convected by steady low-Reynolds number Poiseuille flow through a microchannel À Determine the characteristics of the particle images (e.g. signal-to-noise ratio, particle concentration, time between the images within a ÒrawÓ image pair, exposure time) and the characteristics of the structured illumination (e.g. spatial frequency, phase) required to obtain optimal results for SIMÑspecifically, to minimize/eliminate (images of) out-of-focus particles À Implement SIµPIV: in other words, process a pair of SIM images (where each SIM image is obtained from a pair of ÒrawÓ particle images) to obtain velocity profiles in steady Poiseuille flow À Quantify the spatial resolution along the optical axis of our SIµPIV results based on its well-known parabolic velocity profile, and compare the spatial and temporal resolutions of SIµPIV with that for ÒclassicÓ µPIV using correlation averaging.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 06, 2018
- Source ID
- W911NF1710389
Entities
People
- Minami Yoda
Organizations
- Army Contracting Command
- Georgia Tech Research Corporation
- United States Army