We have developed a portable, breast margin assessment probe leveraging diffuse optical spectroscopy to quantify the morphological landscape of breast tumor margins during breast conserving surgery. The approach presented here leverages a custom-made 16-channel annular photodiode imaging array (arranged in a 4×4 grid), a raster-scanning imaging platform with precision pressure control, and compressive sensing with an optimized set of eight wavelengths in the visible spectral range. A scalable Monte-Carlo-based inverse model is used to generate optical property [μs′(λ) and μa(λ)] measures for each of the 16 simultaneously captured diffuse reflectance spectra. Subpixel sampling (0.75 mm) is achieved through incremental x, y raster scanning of the imaging probe, providing detailed optical parameter maps of breast margins over a 2×2 cm2 area in ∼9 min. The morphological landscape of a tumor margin is characterized using optical surrogates for the fat to fibroglandular content ratio, which has demonstrated diagnostic utility in delineating tissue subtypes in the breast.
Spatially–resolved diffuse reflectance (SRDR) measurements provide photon path information, and enable layered tissue analysis. This paper presents experimental SRDR measurements on two-layer PDMS skin tissue-mimicking phantoms of varying top layer thicknesses, and bulk phantoms of varying optical properties using concentric multi-pixel photodiode array (CMPA) probes, and corresponding forward Monte Carlo simulations. The CMPA is the most densely packed semiconductor SRDR probe reported to date. Signal contrasts between the single layer phantom and bi-layer phantoms with varying top layer thicknesses are as high as 80%. The mean error between the Monte Carlo simulations and the experiment is less than 6.2 %.
Transparent conductive oxide (TCO) films are proposed as electrode materials for direct current injection optical
microcavity devices. Four types of planar indium-tin-oxide (ITO) clad optical microcavities -1-D photonic crystal
nanobeam, 2-D photonic crystal slab, 3-D photonic crystal and microdisk are designed and analyzed both by perturbation
theory and 3D finite difference time domain (FDTD) analysis. The quality (Q) factors of cavities obtained by
perturbation theory in which imaginary part of the dielectric constant of ITO is introduced as a perturbation agree with
those obtained from FDTD method. Microcavities analyzed in this work still preserve high Q-factor in the presence of
metal clad and would provide an excellent heat sink and efficient carrier injection for electrically-driven continuous-wave,
room-temperature microlasers.
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