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Title Investigation of Laser Speckle Contrast Imaging's Sensitivity to Flow
Publication Date
Degree MS
Discipline/Department Physics
Degree Level masters
University/Publisher Miami University
Abstract This thesis presents data from a series of experiments that investigate the ability of laser speckle contrast imaging (LSCI) to sense changes in flow in turbid media. I first provide a theoretical overview and a description of the experimental approach used in this flow imaging technique. Experimental validation of the technique’s ability to sense induced changes in blood flow in the human forearm is demonstrated. Then, the technique’s sensitivity to buried flow in controlled optical phantoms is examined. It is shown that the buried depth and optical properties of the media surrounding flow impact the measured flow indices. Lastly, a study shows how the polarization state of the imaged light impacts the flow measurements as a function of the buried depth and rate of the flow. The results demonstrate that the measurements are dependent on the flow rates and optical properties of the sample as well as the imaging setup used to capture the speckle.
Subjects/Keywords Biomedical Research; Biophysics; Optics; Medical Imaging; Physics; laser speckle; laser speckle contrast imaging; flow imaging; dynamic light scattering; coherence imaging; biomedical imaging; blood flow measurement; flow phantom
Contributors Vishwanath, Karthik (Advisor)
Language en
Rights unrestricted ; This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
Country of Publication us
Format application/pdf
Record ID oai:etd.ohiolink.edu:miami153256524246362
Repository ohiolink
Date Indexed 2020-10-19
Grantor Miami University

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…statistics of speckle patterns and that which relates dynamic speckle to the velocity of scatterers. A brief historical description of LSCI and its applications is also presented. 2 Chapter 2 is used to describe the experimental approach that was used to…

…to LSCI [16]. The filters were mounted in the path of the illuminating light. The speckle intensity should be distributed within the dynamic range of the camera being used to image the sample so that all speckle fluctuations can be sensed by…

…Figure 10. Schematic of the imaging system used to collect speckle images. Flip mirrors were used to select the illumination source. FM: Flip mirror; BB: Beam block; M: Mirror; ND: Neutral density filter; GD: Ground-glass diffuser; d: channel depth…

…22 Figure 11. The raw speckle image (Fig. 11a) and the LSCI flow map of 𝜏c-1 (Fig. 11b) computed using Eq. (1). Horizontal blue lines indicate the inner diameter of the flow channel and black (or gray) boxes…

…provides a schematic of the imaging system that is pictured in Fig. 16b used to collect speckle images. D: Ground diffuser; BE: Beam expander; P1: Illumination linear polarizer; M: Mirror; P2: Imaging linear polarizer; C: Camera…

…29 Figure 17. An image of the flow phantom (Fig. 17a) and captured raw speckle image (Fig. 17b) using cross polarization at the baseline depth (+0.0 mL). The yellow rectangle indicates the ROI in which the mean flow index…

…shows the PDFs of the cross (red) and parallel (blue) static speckle images. The figure on the right (Fig. 18b) shows that of the unpolarized static speckle (black). Fig. 18b also displays the convolution of the…

…two polarized speckle PDFs (purple) as well as twice the convolution (green). ................................................ 32 Figure 19. These figures show the LSCI flow measurements as a function of the pump rate with +0.0 mL…