Speckle patterns offer valuable insights into the surface characteristics or the characteristics of the light generating the speckle. One possible way to extract this information is via spectral speckle correlation (SSC). The cross-correlation between two speckle fields, generated at different wavelengths, can be used for example to determine the roughness of the illuminated surface. Taking defocused measurements of the surface or measuring on a tilted surface leads to a displacement between the speckle, which in turn affects the cross-correlation and leads to errors in the calculated roughness. In this work we present a model to determine the lateral speckle displacement for a change in wavelength in the case of subjective speckle and defocused, tilted objects. This model is therefore applicable to a wide range of applications and allows to estimate and correct for this speckle displacement. Experimental results show sub-pixel accuracy for object tilts up to ±7° and defocus distances up to ±25 mm.
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http://dx.doi.org/10.1364/OE.516122 | DOI Listing |
Ultrasound Med Biol
January 2025
Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong; Biomedical Engineering Programme, The University of Hong Kong, Hong Kong. Electronic address:
Objective: Near-field (NF) clutter filters are critical for unveiling true myocardial structure and dynamics. Randomized singular value decomposition (rSVD) stands out for its proven computational efficiency and robustness. This study investigates the effect of rSVD-based NF clutter filtering on myocardial motion estimation.
View Article and Find Full Text PDFFront Bioeng Biotechnol
December 2024
Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.
In this work, a cost-effective, scalable pneumatic silicone actuator array is introduced, designed to dynamically conform to the user's skin and thereby alleviate localised pressure within a prosthetic socket. The appropriate constitutive models for developing a finite element representation of these actuators are systematically identified, parametrised, and validated. Employing this computational framework, the surface deformation fields induced by 270 variations in soft actuator array design parameters under realistic load conditions are examined, achieving predictive accuracies within 70 µm.
View Article and Find Full Text PDFUltrasound Med Biol
February 2025
University Hospital Münster, Clinic of Obstetrics and Gynecology, Münster, Germany.
Objectives: This study aimed to investigate dyssynchronous heart failure in fetuses of mothers with diabetes mellitus (FDM) and fetal controls (FC) using two-dimensional speckle tracking echocardiography (2D-STE) and novel M-mode prototype software (PS).
Methods: In this cohort study 174 fetuses were analyzed, 87 in the FDM-cohort and 87 gestational age-matched fetuses in the FC-cohort. A subgroup of 38 fetuses formed the final case group, with a high median frame rate of approximately 160 frames/s.
J Biomech Eng
January 2025
School of Medicine, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105.
This study presents a novel technique to measure the motion of the eyelid during blinking. High-speed imaging and digital image correlation (DIC) were employed to monitor the eyelid during blinking in a noninvasive manner. Both spontaneous and reflex blinks were studied.
View Article and Find Full Text PDFUltrasound Med Biol
February 2025
Faculty of Medicine, Institute of Anatomy, University of Ljubljana, Ljubljana, Slovenia. Electronic address:
Objective: This study aimed to develop, validate and test the clinical feasibility of ultrasound (US) speckle tracking method based on gradient optical flow for quantifying small longitudinal displacements, shear and strain in peripheral nerves.
Methods: The speckle tracking method was validated using seven thawed, fresh-frozen isolated cadaveric forearms. Longitudinal motion of the median nerve was captured using a high-frequency 22 MHz linear probe.
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