Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2609.33790

Multi-Aperture PPG with MAPIS: Spatial Optical and Temporal Coherence Fields

Shuguang Wang·Yuanjing Wang
View original source ↗Read source document ↗Export metadata ↓

Abstract

Conventional reflectance photoplethysmography (PPG) typically reduces tissue optical responses to one or a few detector channels. Matrix Pinhole Image Sensing (MAPIS) instead simultaneously samples multiple aperture-dependent optical signals. We analyzed 44 recordings of 30 seconds each from a single MAPIS device to characterize the spatial relationships among DC intensity, pulsatile AC, perfusion index (PI), and temporal coherence across Red and infrared channels. AC increased sublinearly with DC at both wavelengths, resulting in higher PI toward lower-DC apertures, consistent with a first-order relative path-sensitivity interpretation. A second counterintuitive spatial trend was observed in temporal coherence: lower-DC and lower-AC apertures exhibited higher autocorrelation and greater cardiac-periodic spectral concentration. IR signals also showed consistently higher temporal coherence than corresponding Red signals. These observations demonstrate that multi-aperture PPG resolves reproducible spatial relationships among optical intensity, fractional pulsatile sensitivity, and waveform coherence that are largely averaged together in conventional single-channel PPG. The present study establishes within-device relationships and motivates controlled studies of the underlying photon-path mechanisms.

Explore related subjects

physics.opticscs.CV

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Shuguang Wang, Yuanjing Wang. 2026-09-27. Multi-Aperture PPG with MAPIS: Spatial Optical and Temporal Coherence Fields. https://arxiv.org/abs/2609.33790

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Design Principles for Tailoring Heat Transport via Iris-Gated Core-Double-Shell Nanoparticles in the Context of Photothermal Therapies

The rational design of Janus nanostructures that combine efficient optical absorption with controlled thermal transport is essential for advancing plasmonic photothermal therapies and related applications. Here, we introduce a theoretical and computational framework to investigate core-double-shell nanoparticles and their asymmetric version, the iris-gated core-double-shell architecture. The optical response of the structures is first evaluated using generalized Mie theory and subsequently validated through FEM and FDTD simulations, ensuring a consistent description of their electromagnetic and thermal behavior. To systematically map the space of variables, we defined a multi-objective figure of merit that integrates absorption efficiency, absorption cross section, and polymer-layer thickness. Furthermore, we define a thermal gain parameter that quantifies energy densification and complements the analysis of thermal directionality. Our results reveal a near-optimal configuration with parameters ($r_c$, $δ_{Au}$, $δ_p$, $θ$)=(36 nm, 5 nm, 40 nm, 70$°$), capable of producing a temperature rise of 20-23 $°$C, with 67% of the thermal fluz directed toward the upper hemispace and yielding 50% focusing enhancement relative to the symmetric case. This design preserves geometric simplicity and high symmetry while delivering robust thermal asymmetry, thereby facilitating experimental implementation. Beyond photothermal therapies, the proposed methodology constitutes a versatile platform for the rapid screening and optimization of layered nanostructures, adaptable to diverse materials, excitation wavelengths, and functional objectives in nanophotonics.

physics.optics↗
arXiv2026

Quantification of phase instabilities in amplitude swing for ultrashort pulse train characterization

The temporal dynamics of ultrashort pulses are a fundamental feature in ultrafast optics. These dynamics can often be extracted from a two-dimensional trace consisting of a set of nonlinear spectra, using an iterative algorithm. Typically, the measurement of this trace requires integrating the signal of many pulses, which implies that the trace does not correspond to a single pulse when shot-to-shot variations occur. In this case, the pulse train can be characterized by a base pulse and a metric that quantifies its instabilities. Here, we demonstrate that the amplitude swing technique is highly sensitive to pulse-train instabilities, allowing not only for their detection but, crucially, for their quantification. First, we examine the analytical components of the amplitude swing trace. We then introduce a robust parameter designed to assess the instabilities, evaluating its performance in the presence of noise. Finally, we validate this approach using simulated unstable pulse trains, introducing random spectral phase fluctuations, establishing amplitude swing as a simple yet powerful diagnostic tool for full pulse-train characterization.

physics.optics↗
arXiv2026

Image-based investigation of the zebrafish developmental process using in vivo dynamic and multi-contrast optical coherence tomography

We demonstrate in vivo dynamic optical coherence tomography (DOCT) imaging of zebrafish development from 2 weeks to 12 months post-fertilization, integrated with polarization-sensitive OCT (PS-OCT), OCT angiography (OCTA), and histological validation. Two DOCT algorithms were utilized: logarithmic intensity variance and late OCT correlation decay speed, which characterize the occupancy of dynamic scatterers and their motion speeds, respectively. Our results show that skin stripes exhibit high DOCT signals and it varies among the pigment-cell types. Furthermore, the combination of DOCT and PS-OCT captures the maturation of these stripes. In addition, DOCT and OCTA successfully visualized the developmental progression of blood and lymphatic vessels, as well as spinal tissues.

physics.optics↗