Zobrazení zdroje stránky Abbottstaal2040

A real-time, nondestructive mid-infrared (mid-IR) platform was proposed for isotopic methane detection. The measurement system consisted of a tunable mid-IR laser, a miniaturized gas chamber, and a mid-IR signal receiver. The isotope ratio of the 12CH4/13CH4 was identified by measuring the mid-IR spectrum at λ=3.2-3.5µm.In-situ12CH4/13CH4 monitoring was then achieved by tracing the characteristic mid-IR absorption peaks assigned to the 12CH4 at λ=3.328µm and 13CH4 at λ=3.340µm. The real-time methane isotope analysis can be applied to environmental monitoring and petroleum industries.This work reports the development and validation of a new tomography approach, termed cross-interfaces computed tomography (CICT), to address confined-space tomography problems. Many practical tomography problems require imaging through optical walls, which may encounter light refractions that seriously influence the imaging process and deteriorate the three-dimensional (3D) reconstruction. Past efforts have primarily focused on developing open-space tomography algorithms, but these algorithms are not extendable to confined-space problems unless the imaging process from the 3D target and its line-of-sight two-dimensional (2D) images (defined as "projections") is properly adjusted. The CICT approach is therefore proposed in this work to establish an algorithm describing the mapping relationship between the optical signal field of the target and its projections. The CICT imaging algorithm is first validated by quantitatively comparing measured and simulated projections of a calibration plate through an optical cylinder. Then the CICT reconstruction is numerically and experimentally validated using a simulated flame phantom and a laminar cone flame, respectively. Compared to reconstructions formed by traditional open-space tomography, the CICT approach is demonstrated to be capable of resolving confined-space problems with significantly improved accuracy.The study of Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) instabilities in a planar geometry at high energy densities at the National Ignition Facility (NIF) requires high spatial resolution imaging. We demonstrate the potential of Fresnel zone plates (FZPs) to achieve resolution that would unlock such studies. FZPs are circular aperiodic gratings that use diffraction to focus x rays and produce an image with high spatial resolution. Taking into account the NIF's challenging environment, we have designed a specific array of five FZPs for a zinc backlighter to take a radiograph of a target with 9 keV x rays. We measured a mean resolution for the FZP of 1.9µm±0.5µm and a ±1mm depth of focus at an x-ray calibration facility as well as a 2.3µm±0.4µm resolution on a resolution wire mesh shot on the NIF. We also performed an in-depth analysis of the image quality to assess the capability to resolve the small features present in RT and RM instabilities.With the rapid development of digital precision medicine, the digital polymerase chain reaction (dPCR) deoxyribonucleic acid (DNA) gene chip integrates more channels with smaller size and larger area, which leads to a higher technical requirement for commercial optical fluorescence microscopy. The multitime image splicing method is widely used for DNA detection. However, it consumes time and has visible seamless image results. This work has demonstrated the design and fabrication of a three channel reversed and reduced fluorescence microscopic imaging system with high-resolution and large field of view for one-time imaging. We introduced the super ultra-thin dichroic mirror into the space between the objective lens and the gene chip to achieve a uniform illumination and a strong signal for the large area gene chip. The fabricated new fluorescence microscopy can take a one-time imaging for the 28×18mm dPCR gene chip with more than 20,000 multi micro-droplets within FAM, HEX, and ROX fluorescence channels. The optical system was designed with a numerical aperture (NA) of 0.106. Modulation transfer function (MTF) is higher than 0.675 at 70 lp/mm, and the function resolution capability is 10 µm with the whole magnification of -0.65times. The fly's eye lens-based illumination system was tested with a uniform output of over 90% in the whole ϕ34.7mm chip area. The design was tested, and the experimental results showed that this new system provides a fast, efficient, and professional optical imaging method for detection of the new emerged digital PCR gene chip, which has larger area and more channels.Phase retrieval is a highly useful technique that allows the calculation of the complex electric field of a beam of spatially coherent radiation based only on recordings of intensity profiles with a camera. In this work, we demonstrate what we believe, to the best of our knowledge, is a new technique for single-beam multiple-intensity phase retrieval based on simultaneous propagations that provides improved fidelity results compared to standard methods (0.9931 compared to 0.9646) and a 34 dB reduction in background noise level. The implementation is fast, open source, user friendly, and can be run on either CPUs or GPUs. It is available for download at https//gitlab.gbar.dtu.dk/biophotonics/PhaseRetrieval.The technology of a microlens array scanner (MLAS) has the potential to realize large-angle beam scanning with a large beam size. Two sets of microlens arrays (MLAs) were used as phase-controlling emitters in MLAS. A mathematical model of the MLAS with Kepler structure was established in the desired direction and leakage direction. It was verified that the maximum relative displacement of MLAS was half of the MLA sub-aperture. Two sets of F/5 continuous surface MLAs were used as emitters in the experiment. One-dimensional discrete-addressing scanning process with ∼10∘ field of view is demonstrated, and it is in good agreement with the theory.In this paper, efficient individual and joint constant amplitude zero auto-correlation (CAZAC) precoding schemes are proposed to improve the performance of an indoor multiple-input multiple-output-orthogonal frequency division multiplexing (MIMO-OFDM)-based visible light communication (VLC) system. By considering the proposed precoding scheme, a 3×3 MIMO-OFDM VLC system with symmetrical and asymmetrical structure is set up, whose peak-to-average-power ratio (PAPR) of transmitted signal, signal-to-noise ratio (SNR), and bit error rate performance are investigated. It is shown that both individual and joint CAZAC precoding schemes can reduce the PAPR of the transmitted signal and make the SNR uniform over data subcarriers, resulting in significant performance improvement compared to the system without precoding. It is demonstrated that there are similar performance improvements for the MIMO-OFDM VLC system using the individual CAZAC precoding and joint CAZAC precoding in a symmetric scenario. [https://www.selleckchem.com/products/uamc-3203.html Selleck UAMC-3203] At the expense of higher implementation complexity, the joint CAZAC precoding has more performance benefits than the individual CAZAC precoding for the VLC system with asymmetrical MIMO.