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High Throughput AOTF Hyperspectral Imager for Randomly Polarized Light
摘要： The acousto-optic tunable filter (AOTF) is one of the most used techniques for hyperspectral imaging (HSI), and is capable of fast and random wavelength access, high diffraction efficiency, and good spectral resolution. Typical AOTF-HSI works with linearly polarized light; hence, its throughput is limited for randomly polarized applications such as fluorescence imaging. We report an AOTF-based imager design using both polarized components of the input light. The imager is designed to operate in the 450 to 800 nm region with resolutions in the range of 1.5–4 nm. The performance characterization results show that this design leads to 68% improvement in throughput for randomly polarized light. We also compared its performance against a liquid crystal tunable filter (LCTF)-based imager.
关键词： hyperspectral imaging,LCTF,AOTF,optical throughput
更新于2025-09-23 15:22:29
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The AOTF-based NO<sub>2</sub> camera
摘要： The abundance of NO2 in the boundary layer relates to air quality and pollution source monitoring. Observing the spatiotemporal distribution of NO2 above well-delimited (flue gas stacks, volcanoes, ships) or more extended sources (cities) allows for applications such as monitoring emission fluxes or studying the plume dynamic chemistry and its transport. So far, most attempts to map the NO2 field from the ground have been made with visible-light scanning grating spectrometers. Benefiting from a high retrieval accuracy, they only achieve a relatively low spatiotemporal resolution that hampers the detection of dynamic features. We present a new type of passive remote sensing instrument aiming at the measurement of the 2-D distributions of NO2 slant column densities (SCDs) with a high spatiotemporal resolution. The measurement principle has strong similarities with the popular filter-based SO2 camera as it relies on spectral images taken at wavelengths where the molecule absorption cross section is different. Contrary to the SO2 camera, the spectral selection is performed by an acousto-optical tunable filter (AOTF) capable of resolving the target molecule's spectral features. The NO2 camera capabilities are demonstrated by imaging the NO2 abundance in the plume of a coal-fired power plant. During this experiment, the 2-D distribution of the NO2 SCD was retrieved with a temporal resolution of 3 min and a spatial sampling of 50 cm (over a 250 × 250 m2 area). The detection limit was close to 5 × 1016 molecules cm?2, with a maximum detected SCD of 4 × 1017 molecules cm?2. Illustrating the added value of the NO2 camera measurements, the data reveal the dynamics of the NO to NO2 conversion in the early plume with an unprecedent resolution: from its release in the air, and for 100 m upwards, the observed NO2 plume concentration increased at a rate of 0.75–1.25 g s?1. In joint campaigns with SO2 cameras, the NO2 camera could also help in removing the bias introduced by the NO2 interference with the SO2 spectrum.
关键词： NO2,AOTF,plume,remote sensing,air quality,camera,acousto-optical tunable filter
更新于2025-09-23 15:22:29
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[IEEE 2018 Second International Conference on Computing Methodologies and Communication (ICCMC) - Erode (2018.2.15-2018.2.16)] 2018 Second International Conference on Computing Methodologies and Communication (ICCMC) - STORE WHEN BLOCKED AFTER FAIR PRIORITIZED PREEMPTION (SBFPP) PROTOCOL FOR NON BLOCKING OPTICAL BURST SWITCHED NETWORKS
摘要： Just Enough Time is the most promising protocol of optical burst switched network, Different prioritization on the basis of fairness algorithms have been given for increasing the utilization of link. Still there is probability of blocking in the network at high load. In this Paper we have proposed a none blocking Optical Burst Switched network by proposing a new protocol for optical Burst switched network. In this paper we have also compared the blocking probabilities of JET with some fairness protocols with our proposed protocol. A simulated output for effective bandwidth utilization and dropping probabilities of all the outputs are also presented and compared.
关键词： Fair Prioritized Preemption (FPP),Acoustic Optical tunable filter (AOTF),Optical Burst Switching,Last available unscheduled channel with void filling (LAUC-VF)
更新于2025-09-23 15:21:01