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过滤筛选
- 2017
- spectral reconstruction
- interference
- polarization
- transform
- imaging spectrometer
- Optoelectronic Information Science and Engineering
- BITTT
- Zhejiang University
- Guilin University of Aerospace Technology
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Freezing Induced Turn-on Modality for Real-time Imaging in Cryosurgery
摘要： Cryosurgery has attracted great attention for the treatment of tumors due to its obvious advantages. However, it still remains a challenge to determine the volume of frozen tissues in real-time, which greatly lowers the therapeutic efficacy of cryosurgery and hinders its broad application for the treatment of cancers. Herein, we report a freezing induced turn-on strategy for selective real-time imaging of frozen cancer cells. As a type of aggregation induced emission (AIE) fluorogen, TABD-Py molecules interact specifically with ice crystals and form aggregates at the ice/water interface. Consequently, bright fluorescent emission appears upon freezing. Note that TABD-Py molecules are enriched only in the cancer cells and exhibit high biocompatibility as well as low cytotoxicity, therefore a freezing induced turn-on imaging modality for cryosurgery is developed, which will certainly maximize therapeutic efficacy of cryosurgery in treating tumors.
关键词： aggregation induced emission,cancer cells,real-time imaging,freezing,cryosurgery
更新于2025-09-23 15:23:52
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Chemical and topographical single-cell imaging by near-field desorption mass spectrometry
摘要： Simultaneous acquiring chemical and topographical information within a single cell at nanoscale resolutions is vital to cellular biology, yet it remains a great challenge for current techniques due to limited lateral resolutions and detection sensitivities. Here we report the development of near-field desorption mass spectrometry for co-registered chemical and topographical imaging, thereby bridging the gap between laser-based MS methods and multimodal single-cell imaging. Using this integrated platform, imaging resolution of 250 nm and 3D topographically reconstructed chemical single-cell imaging were achieved. This technique offers more in-depth cellular information than is currently possible with micrometre-range laser-based MS imaging methods. Considering the simplicity and compact size of the near-field device, this technique can be introduced to matrix-assisted laser desorption ionization MS, expanding the multimodal abilities of MS at nanoscale resolutions across wide disciplines.
关键词： single-cell analysis,analytical methods,multimodal imaging,mass spectrometry,near-field desorption
更新于2025-09-23 15:23:52
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Detection and visualization of water surface three-wave resonance via a synthetic Schlieren method
摘要： Three-wave resonance is one of the most fundamental energy-transfer mechanisms that can occur among weakly nonlinear surface waves. Here we show experimentally that if two source waves are propagating at an angle to each other, the conditions for three-wave resonances are satisfied and a third resultant wave is produced. We present 3D visualization of surface waves using the Free-Surface Synthetic Schlieren (FS-SS) method, which removes the need for the addition of a light-diffusing agent, thereby retaining the surface tension and viscous properties of water. For three triad frequencies, we compute the average temporal power spectral density (PSD) of the wave heights. The direction of wave propagation is visualized by integrating the temporal PSD and by obtaining the average spatial PSD for each triad. Our results are in good agreement with the theory.
关键词： Hydrodynamic waves,Signal Processing,Flow visualization and imaging
更新于2025-09-23 15:23:52
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Spatial and Temporal Stability of Airglow Measured in the Meinel Band Window at 1191.3 nm
摘要： We report on the temporal and spatial fluctuations in the atmospheric brightness in the narrow band between Meinel emission lines at 1191.3 nm using a λ/Δλ = 320 near-infrared instrument. We present the instrument design and implementation, followed by a detailed analysis of data taken over the course of a night from Table Mountain Observatory. At low airmasses, the absolute sky brightness at this wavelength is found to be 5330 ± 30 nW m?2 sr?1, consistent with previous measurements of the inter-band airglow at these wavelengths. This amplitude is larger than simple models of the continuum component of the airglow emission at these wavelengths, confirming that an extra emissive or scattering component is required to explain the observations. We perform a detailed investigation of the noise properties of the data and find no evidence for a noise component associated with temporal instability in the inter-line continuum. This result demonstrates that in several hours of ～100 s integrations the noise performance of the instrument does not appear to significantly degrade from expectations, giving a proof of concept that near-infrared line intensity mapping may be feasible from ground-based sites.
关键词： techniques: imaging spectroscopy,site testing,atmospheric effects
更新于2025-09-23 15:23:52
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Achievable noise performance of spectroscopic prototype DEPFET detectors
摘要： A new generation of spectroscopic X-ray DEPFET detectors has been produced in the course of the detector development for the Wide Field Imager (WFI) of Athena. These devices served to perform a detailed analysis of the noise composition, which was enabled by the development of appropriate test algorithms. A result of the analysis is the distinction of different components, which sum up to the total noise. In particular the contribution of shot noise, white noise and 1/f noise to the readout noise is determined as well as the signal noise caused by the generation of charge carriers. The resulting parametrization enables the adaptation and optimization of operation modes to given purposes. The studied prototype detectors included 64×64 pixels with a linear gate design and provided an excellent noise, below 1.6 e?ENC at a readout time faster than 10 μs/pixel and a temperature of -80 ?C in rolling-shutter operation. This performance is enabled by an extended signal integration time. A further noise reduction is prevented by the signal noise, caused by charge carrier generation. In order to demonstrate the low noise properties of the DEPFET transistor, the measurement conditions were adapted and a noise of 0.95 e?ENC was measured at the expense of the sensor size — by operating only parts of the sensor in window mode — and dynamic range — by using the Al Kα line at about 1.49 keV for calibration.
关键词： Imaging spectroscopy,Solid state detectors,Instrumental noise,X-ray detectors and telescopes
更新于2025-09-23 15:23:52
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Using a commercial mini-X-ray source for calibrating Bragg crystals
摘要： In this paper we describe a procedure for calibration of Bragg crystals used for X-ray spectroscopy of laser plasmas. The method uses a relatively inexpensive commercially available X-ray source. By using the source to pump a metallic foil such as vanadium or titanium we were able to create a K-α emission source with minimal background radiation outside the desired photon energy. By using photon counting techniques with a CCD detector we were able to get absolute calibrations of curved and flat Bragg crystals in the 4–5 keV region. An important advantage of our method is that absolute calibration was not necessary either for the commercial source or the detector.
关键词： X-ray detectors and telescopes,spectroscopy and imaging,Plasma diagnostics - interferometry
更新于2025-09-23 15:23:52
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Spectroscopic DEPFETs at high frame rates using window mode
摘要： An active pixel sensor like an array of DEPFET (DEpleted P-channel Field Effect Transistor) pixels allows for very flexible operation modes and an adaptability of the sensor design to the specific needs of the scientific instrument objectives. For a very high time resolution at the order of one microsecond, a full parallel readout of all pixels is required. Every readout node needs to be connected to readout electronics separately. Furthermore, to preserve a good spectroscopic performance, the integration of a storage functionality into each pixel prevents the influence of events occurring during the readout process and provoking an incorrect energy information. The energy of such events is detected incorrectly and is not falsifiable with a subsequent analysis. An active pixel sensor based on a DEPFET with internal storage and wired for full parallel readout is in production and will be available for testing in the future. Alternatively, the ability of an active pixel sensor to be read out in window (region-of-interest readout) mode allows for the investigation of the behavior at high frame rates at the order of 100 kHz for DEPFET devices with and without storage functionality.
关键词： Imaging spectroscopy,Solid state detectors,X-ray detectors and telescopes
更新于2025-09-23 15:23:52
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Research on feature point extraction and matching machine learning method based on light field imaging
摘要： At present, there are many methods to realize the matching of specified images with features, and the basic components include image feature point detection, feature description, and image matching. Based on this background, this article has done different research and exploration around these three aspects. The image feature point detection method is firstly studied, which commonly include image edge information-based feature detection method, corner information-based detection method, and various interest operators. However, all of the traditional detection methods are involved in problems of large computation burden and time consumption. In order to solve this problem, a feature detection method based on image grayscale information-FAST operator is used in this paper, which is combined with decision tree theory to effectively improve the speed of extracting image feature points. Then, the feature point description method BRIEF operator is studied, which is a local expression of detected image feature points based on descriptors. Since the descriptor does not have rotation invariance, the detection operator is endowed by a direction that is proposed in this paper, and then the local feature description is conducted on the feature descriptor to generate a binary string array containing direction information. Finally, the feature matching machine learning method is analyzed, and the nearest search method is used to find the nearest feature point pair in Euclidean distance, of which the calculation burden is small. The simulation results show that the proposed nearest neighbor search and matching machine learning algorithm has higher matching accuracy and faster calculation speed compared with the classical feature matching algorithm, which has great advantages in processing a large number of array images captured by the light field camera.
关键词： Nearest neighbor search,Light field imaging,Image matching,Machine learning
更新于2025-09-23 15:23:52
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Performance simulation of a MRPC-based PET imaging system
摘要： The less expensive and high resolution Multi-gap Resistive Plate Chamber (MRPC) opens up a new possibility to find an efficient alternative detector for the Time of Flight (TOF) based Positron Emission Tomography, where the sensitivity of the system depends largely on the time resolution of the detector. In a layered structure, suitable converters can be used to increase the photon detection efficiency. In this work, we perform a detailed GEANT4 simulation to optimize the converter thickness towards improving the efficiency of photon conversion. A Monte Carlo based procedure has been developed to simulate the time resolution of the MRPC-based system, making it possible to simulate its response for PET imaging application. The results of the test of a six-gap MRPC, operating in avalanche mode, with 22Na source have been discussed.
关键词： Gaseous imaging and tracking detectors,Gaseous detectors
更新于2025-09-23 15:23:52
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Hyperspectral band selection for soybean classification based on information measure in FRS theory
摘要： Soybeans and soy foods have attracted widespread attention due to their health benefits. Special varieties of soybeans are in demand from soybean processing enterprises. Because of the advantage of rapid measurement with minimal sample preparation, hyperspectral imaging technology is used for classifying soybean varieties. Based on fuzzy rough set (FRS) theory, the research of hyperspectral band selection can provide the foundation for variety classification. The performance of band selection with Gaussian membership functions and triangular membership functions under various parameters were explored. Appropriate ranges of parameters were determined by the number of bands and mutual information of subsets relative to the decision. The effectiveness of the proposed algorithms was validated through experiments on soybean hyperspectral datasets by building two classification methods, namely Extreme Learning Machine and Random Forest. Compared with ranking methods, the proposed algorithm provides a promising improvement in classification accuracy by selecting highly informative bands. To further reduce the size of the subset, a post-pruning design was used. For the Gaussian membership function, a subset containing eight bands achieved an average accuracy of 99.11% after post-pruning. As well as classification accuracy, we explored stability of band selection algorithm under small perturbations. The band selection algorithm of the Gaussian membership function was more stable than that of the triangular membership function. The results showed that the information measure (IM) based band selection algorithm is effective at obtaining satisfactory classification accuracy and providing stable results under perturbations.
关键词： Soybean classification,Information measure,Band selection,Fuzzy rough set,Hyperspectral imaging
更新于2025-09-23 15:23:52