arXiv subjects

Carlas S. Smith

Publications and source records attributed to Carlas S. Smith.

4 recordsLinked to original sources

arXiv2024

Speckle-based 3D sub-diffraction imaging through a multimode fiber

A flexible multimode fiber is an exceptionally efficient tool for in vivo deep tissue imaging. Recent advances in compressive multimode fiber sensing allow for imaging with sub-diffraction spatial resolution and sub-Nyquist speed. At present, the technology is limited to imaging in a two-dimensional (2D) plane near the fiber distal facet while in real applications it is very important to visualize three-dimensional (3D) structures. Here we propose a new approach for fast sub-diffraction 3D imaging through a multimode fiber by using a single 2D scan, speckle illumination, and bucket detection. We experimentally demonstrate precise image plane location as well as 3D imaging of samples with various scattering coefficients. The full width at half maximum (FWHM) of the point spread function along the axial direction is 3 times smaller than the diffraction limit. Our study grants depth-resolving capacity to ultra-thin super-resolution fiber endoscopes for life science and medical applications.

physics.optics↗

arXiv2023

Laser-Induced Cavitation for Controlling Crystallization from Solution

We demonstrate that a cavitation bubble initiated by a Nd:YAG laser pulse below breakdown threshold induces crystallization from supersaturated aqueous solutions with supersaturation and laser-energy dependent nucleation kinetics. Combining high-speed video microscopy and simulations, we argue that a competition between the dissipation of absorbed laser energy as latent and sensible heat dictates the solvent evaporation rate and creates a momentary supersaturation peak at the vapor-liquid interface. The number and morphology of crystals correlate to the characteristics of the simulated supersaturation peak.

physics.chem-ph↗

arXiv2023

Low-cost fluorescence microscope with microfluidic device fabrication for optofluidic applications

Optofluidic devices have revolutionized the manipulation and transportation of fluid at smaller length scales ranging from micrometers to millimeters. We describe a dedicated optical setup for studying laser-induced cavitation inside a microchannel. In a typical experiment, we use a tightly focused laser beam to locally evaporate the solution laced with a dye resulting in the formation of a microbubble. The evolving bubble interface is tracked using high-speed microscopy and digital image analysis. Furthermore, we extend this system to analyze fluid flow through fluorescence$-$Particle Image Velocimetry (PIV) technique with minimal adaptations. In addition, we demonstrate the protocols for the in-house fabrication of a microchannel tailored to function as a sample holder in this optical setup. In essence, we present a complete guide for constructing a fluorescence microscope from scratch using standard optical components with flexibility in the design and at a lower cost compared to its commercial analogues.

physics.ins-det↗

arXiv2023

Resolving Power of Visible to Near-Infrared Hybrid $β$-Ta/NbTiN Kinetic Inductance Detectors

Kinetic Inductance Detectors (KIDs) are superconducting energy-resolving detectors, sensitive to single photons from the near-infrared to ultraviolet. We study a hybrid KID design consisting of a beta phase tantalum ($β$-Ta) inductor and a NbTiN interdigitated capacitor (IDC). The devices show an average intrinsic quality factor $Q_i$ of 4.3$\times10^5$ $\pm$ 1.3 $\times10^5$. To increase the power captured by the light sensitive inductor, we 3D-print an array of 150$\times$150 $μ$m resin micro lenses on the backside of the sapphire substrate. The shape deviation between design and printed lenses is smaller than 1$μ$m, and the alignment accuracy of this process is $δ_x = +5.8 \pm 0.5$ $μ$m and $δ_y = +8.3 \pm 3.3$ $μ$m. We measure a resolving power for 1545-402 nm that is limited to 4.9 by saturation in the KID's phase response. We can model the saturation in the phase response with the evolution of the number of quasiparticles generated by a photon event. An alternative coordinate system that has a linear response raises the resolving power to 5.9 at 402 nm. We verify the measured resolving power with a two-line measurement using a laser source and a monochromator. We discuss several improvements that can be made to the devices on a route towards KID arrays with high resolving powers.

physics.ins-det↗