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Yi-Jing Chen

Publications and source records attributed to Yi-Jing Chen.

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Reconfigurable wavelength-encoded stochastic illumination for active hyperspectral imaging

Traditional hyperspectral imaging (HSI) relies on sequential scanning with complex and bulky hardware, inherently limiting its temporal resolution while increasing system complexity and cost. Computational HSI offers cost-effective alternatives with simplified hardware. However, most existing computational methods rely on fixed spectral encoding units, which lack adaptability for different spectral tasks. Here, we present a reconfigurable optical stochastic encoding (ROSE) framework with programmable illumination, which can be adaptively optimized for different spectral tasks, for high-throughput, compressive HSI. By leveraging an array of monochromatic light-emitting diodes (LEDs), we synthesize stochastic spectral patterns that enable compressive acquisition using a standard monochrome camera. The proposed framework allows dynamic reconfiguration of illumination patterns, making it adaptable to diverse imaging requirements. We experimentally validate the proposed method and achieve HSI with a spatial resolution of 2048 by 1536, reconstructing 60 spectral bands across the spectral range of 400-700 nm. Furthermore, we introduce an automatic optimization strategy to search for optimal illuminations tailored to specific tasks, improving both reconstruction accuracy and task-oriented performance. We demonstrate the effectiveness of our approach in applications including anti-counterfeiting inspection and oral imaging, and further validate its compatibility with standard microscope and endoscope systems. The developed ROSE illumination module could serve as a universal, plug-and-play add-on for conventional cameras and existing optical systems, providing a cost-effective pathway to upgrade them into high-performance, task-adaptive HSI systems.

physics.optics

Triggering the Untriggered: The First Einstein Probe-Detected Gamma-Ray Burst 240219A and Its Implications

The Einstein Probe (EP) achieved its first detection and localization of a bright X-ray flare, EP240219a, on 2024 February 19, during its commissioning phase. Subsequent targeted searches triggered by the EP240219a alert identified a faint, untriggered gamma-ray burst (GRB) in the archived data of Fermi Gamma-ray Burst Monitor (GBM), Swift Burst Alert Telescope (BAT), and Insight-HXMT/HE. The EP Wide-field X-ray Telescope (WXT) light curve reveals a long duration of approximately 160 s with a slow decay, whereas the Fermi/GBM light curve shows a total duration of approximately 70 s. The peak in the Fermi/GBM light curve occurs slightly later with respect to the peak seen in the EP/WXT light curve. Our spectral analysis shows that a single cutoff power-law (PL) model effectively describes the joint EP/WXT--Fermi/GBM spectra in general, indicating coherent broad emission typical of GRBs. The model yielded a photon index of $\sim -1.70 \pm 0.05$ and a peak energy of $\sim 257 \pm 134$ keV. After detection of GRB 240219A, long-term observations identified several candidates in optical and radio wavelengths, none of which was confirmed as the afterglow counterpart during subsequent optical and near-infrared follow-ups. The analysis of GRB 240219A classifies it as an X-ray rich GRB (XRR) with a high peak energy, presenting both challenges and opportunities for studying the physical origins of X-ray flashes, XRRs, and classical GRBs. Furthermore, linking the cutoff PL component to nonthermal synchrotron radiation suggests that the burst is driven by a Poynting flux-dominated outflow.

astro-ph.HE