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Fourier transforms for fast and quantitative Laser Speckle Imaging
摘要： Laser speckle imaging is a powerful imaging technique that visualizes microscopic motion within turbid materials. At current two methods are widely used to analyze speckle data: one is fast but qualitative, the other quantitative but computationally expensive. We have developed a new processing algorithm based on the fast fourier transform, which converts raw speckle patterns into maps of microscopic motion and is both fast and quantitative, providing a dynamnic spectrum of the material over a frequency range spanning several decades. in this article we show how to apply this algorithm and how to measure a diffusion coefficient with it. We show that this method is quantitative and several orders of magnitude faster than the existing quantitative method. finally we harness the potential of this new approach by constructing a portable laser speckle imaging setup that performs quantitative data processing in real-time on a tablet.
关键词： Fast Fourier Transform,Real-time Analysis,Quantitative Imaging,Laser Speckle Imaging,Microscopic Motion
更新于2025-09-12 10:27:22
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Stereoscopic Near-Infrared Fluorescence Imaging: A Proof of Concept Toward Real-Time Depth Perception in Surgical Robotics
摘要： The increasing use of surgical robotics has provoked the necessity for new medical imaging methods. Many assistive surgical robotic systems influence the surgeon’s movements based on a model of constraints and boundaries driven by anatomy. This study aims to demonstrate that Near-Infrared Fluorescence (NIRF) imaging could be applied in surgical applications to provide subsurface mapping of capillaries beneath soft tissue as a method for imaging active constraints. The manufacture of a system for imaging in the near-infrared wavelength range is presented, followed by a description of computational methods for stereo-post-processing and data acquisition and testing used to demonstrate that the proposed methods are viable. The results demonstrate that it is possible to use NIRF for the imaging of a capillary submersed up to 11 mm below a soft tissue phantom, over a range of angles from 0? through 45?. Phantom depth has been measured to an accuracy of ±3 mm and phantom angle to a constant accuracy of ±1.6?. These findings suggest that NIRF could be used for the next generation of medical imaging in surgical robotics and provide a basis for future research into real-time depth perception in the mapping of active constraints.
关键词： real-time image acquisition,NIRF imaging,stereoscopic near-infrared fluorescence,depth perception,active constraints
更新于2025-09-12 10:27:22
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Frequency‐scaled optimized time‐frequency transform for harmonic estimation in photovoltaic‐based microgrid
摘要： Renewable (especially photovoltaic [PV])‐based distributed generations (DGs) integrated via converter stations pose serious challenge against effective monitoring of fundamental and harmonic phasors because of the presence of time‐varying Nth‐order harmonics, which get escalated in terms of voltage flicker, total harmonics distortion profiles with increased penetration level of such renewable sources. The generalized S‐transform (ST) has been used extensively for these nonstationary power signals analysis because it localizes the signal spectrum in time and yields a phase spectrum also for obtaining both amplitude and phase characteristics. However, the transform suffers from large execution time and arbitrary choice of window parameters. The paper, therefore, presents a new approach to extract time‐frequency response (TFR) from a harmonically scaled Fourier kernel ST optimized by metaheuristic firefly algorithm suitable for monitoring of microgrid phasors in real time, which can be ultimately used for effective power management and coordination. This new formulation uses selective frequency scaling to achieve a significant time reduction (within a half cycle of the initiation of the disturbance) in monitoring and tracking time‐varying harmonic disturbances, especially for DG‐integrated operations. Extensive simulation results for monitoring of time‐varying fundamental and harmonics in PV‐based grid‐connected power networks are presented against efficacy measures. Further, to validate in real time, a TMS320 C6713 digital signal processor (DSP) test bench is included in the paper for fundamental and harmonics estimation.
关键词： monitoring,photovoltaic,filtering,nonstationary power signal,harmonics,scaling methods,real‐time S‐transform
更新于2025-09-11 14:15:04
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The Comparison of Thermal Effects of a 1940‐nm Tm:fiber Laser and 980‐nm Diode Laser on Cortical Tissue: Stereotaxic Laser Brain Surgery
摘要： Background and Objectives: The thermal damage on adjacent healthy structures is always an unwanted consequence of continuous‐wave laser irradiation of soft tissues. To propose a laser as an effective alternative to traditional surgical tools, this photothermal damage due to heat conduction must be taken into account with a detailed laser dosimetry study. Two candidate lasers; a 980‐nm diode and 1940‐nm Tm:fiber were selected for this study. Despite the poor absorption by water, the 980‐nm diode laser has been one of the most widely used lasers in soft tissue surgeries due its good absorption by hemoglobin, which provides good homeostasis. The second laser; the Tm:fiber laser was selected due to its wavelength operating at an absorption peak of water (1,940 nm), which makes it a good candidate for ablation of biological tissues, and it is readily capable of being transmitted through flexible fiber optics to deliver energy to hard‐to‐reach regions. The underlying motivation for the research described in this paper is that with a comprehensive comparison of ablation capabilities and a detailed dose study of infrared lasers operating at different wavelengths and temperature monitoring of the tissue during laser surgery, it may be possible to specify the optimal laser parameters for laser surgery, and propose a treatment alternative to conventional surgical techniques in clinical use. The objectives of this study were to investigate and to compare the thermal effects of 980‐nm and 1940‐nm lasers on cortical tissue in vivo, to find the optimum parameters for laser‐brain‐ablation with minimum thermal damage to the surrounding healthy tissue, and finally, to analyze laser irradiated tissue thermographically and histologically to correlate thermal events and tissue damage with laser irradiation parameters. Study Design/Materials and Methods: Stereotaxic laser brain surgeries were performed on 32 male Wistar rats. A t‐type thermocouple was used to measure the temperature of the nearby tissue at a distance of 1 mm above and 1 mm away from the fiber tip during laser surgery. Cresyl fast violet (CFV) staining was used to expose the thermal extent of laser surgery on cortical tissue. Eight tissue samples from each laser study group were processed for histological analysis and the mean ± standard deviation for thermal damage was reported. Thermal damage was quantified as ablation (thermally removed tissue), severe and mild coagulation (irreversible thermal damage) and edematous (reversible thermal damage) areas with regard to CFV stained slices. The Pearson correlation coefficient was calculated to test if the ablation efficiencies and total damage, and edematous areas were correlated to rates of temperature change. Results: No significant adverse effects were observed during surgeries. We found that both lasers investigated were successful in cortical tissue removal. Our results also revealed that irrespective of the mode of operation, laser wavelength and laser power, there is a strong correlation between the rates of temperature change and ablation efficiencies and a negative correlation between the rate of temperature change and total damage and edematous area. Conclusions: Both lasers investigated were successful in cortical tissue removal. We also reported that when the amount of energy delivered to the tissue was constant, the most important issue was to deliver this energy in a short time to achieve more efficient ablations with less edema around the lesion, regardless of mode of delivery (continuous or pulsed‐modulated mode), but further studies including the healing period after laser surgeries have to be performed to compare the thermal extent of damage comprehensively.
关键词： ablation efficiency,rate of temperature change,980‐nm diode laser,Thulium laser,ablation,real‐time temperature monitoring,Laser brain surgery,cortical tissue
更新于2025-09-11 14:15:04
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24.4: <i>Invited Paper:</i> The Breakthrough of large size electrical luminescence H‐Q LED TV, with 4K resolution and top emission device architecture, fabricated by ink jet printing technology
摘要： The domestic rainbow trout producers issued a standard with an aquatic association that classified rainbow trout as salmon, which raised the concern of consumers on the fish parasites infection. Herein, an in situ method was developed using "iKnife" and rapid evaporative ionization mass spectrometry based lipidomics for real-time discrimination of salmon and rainbow trout without sample preparation. A total of 12 fatty acids and 37 phospholipid species was identified and imported into statistical analysis for building an in situ and real-time recognition model. The ions with |p(corr)| > 0.5 and |p| > 0.03 were shown to be responsible for allocating samples, and the ions with high correlation values, such as of m/z 747.50, 771.49, and 863.55, indicated large weights in identification of the salmon and rainbow trout. The results indicated that this technology could be employed as a front-line test method to ensure the authenticity of salmon products.
关键词： real-time identification,rainbow trout,lipidomics,rapid evaporative ionization mass spectrometry,salmon
更新于2025-09-11 14:15:04
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Application of Laser-Induced Breakdown Spectroscopy to Real-Time Elemental Monitoring of Iron and Steel Making Processes
摘要： Steel industry is the irreplaceable foundation in heavy industries, which have been developed and improved. The advanced monitoring methods including detection and control technology contribute to its development of iron and steel manufacturing processes. With the development of the measurement techniques, laser-induced breakdown spectroscopy (LIBS) has been developed and applied for many industrial fields of elemental monitoring due to the non-contact, fast response, high sensitivity, real-time and multi-dimensional features. The elemental measurement methods in steel industry were summarized and compared in this paper. LIBS measurements of raw material, smelting processes, products, slag, etc. have been reviewed in detail. Challenges for the future of LIBS application in iron and steel making processes have also been discussed. LIBS has a high potential to improve the detection ability of elemental analyses and to promote the on-line monitoring characteristics in iron and steel making plants.
关键词： real-time,elemental monitoring,iron and steel making processes,laser-induced breakdown spectroscopy
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Non-Invasive Real-Time Characterization of Hollow-Core Photonic Crystal Fibres using Whispering Gallery Mode Spectroscopy
摘要： Single-ring hollow-core photonic crystal fibre (SR-PCF), consisting of a ring of thin-walled glass capillaries surrounding a central hollow core, can offer remarkably low transmission loss [1], and is finding applications in, e.g., wavelength conversion and pulse compression in gases, high-power beam delivery and circular dichroism [2]. As with all microstructured fibres, it is highly desirable to continuously measure the internal structural parameters (e.g. the capillary diameter) during fibre drawing. This would improve the yield of useful fibre lengths, as well as offering better control of structural uniformity along the fibre. Successful tapering of hollow-core fibres also requires a non-destructive method of verifying structural integrity along the taper. We here report for the first time a non-invasive technique for monitoring the capillary diameter in SR-PCF during the draw. The technique relies on excitation of whispering gallery modes (WGMs) in the capillary walls. The frequency spacing between successive WGMs fulfils the well-known condition: (cid:16)(cid:81)(cid:81)1l(cid:14)l(cid:32)cLcap(cid:173)(cid:176)(cid:174)(cid:176)(cid:175)lnl(cid:14)1,m1(cid:14)((cid:81)l(cid:14)1,(cid:16))mnl,m(cid:81)l,m(cid:189)(cid:176)(cid:190)(cid:176)(cid:191)(cid:124)cLncapWGM(cid:81)(1) where c is the speed of light in vacuum, Lcap is the circumference (~2(cid:652)R, where R is the mean radius), l the azimuthal and m the radial mode order, and nl,m is the effective index of the mode. Both approximate analytical solutions to nl,m and full numerical simulations show that, for the SR-PCFs studied, the approximation in Eq.(1) is accurate to within ±0.9% if nWGM is set to 1.484. As illustrated in Fig. 1 (right), the fibre is illuminated transversally by a broadband light source, thereby exciting WGMs inside selected capillaries. By placing a light collection fibre (400 μm core diameter) at a suitable position ~1 cm from the SR-PCF, the WGM spectrum originating from one of the capillaries could be selectively measured. A fast Fourier transform could then be used, together with Eq. (1), to compute the effective capillary diameter 2R in real-time with sub-micron accuracy. The results shown in Fig. 1 (left) were made at a fibre drawing speed of 32.3 m/min and a spectrometer integration time of 70 ms, corresponding to an axial resolution of <4 cm. We also used the technique to measure the diameter of individual capillaries at points along a tapered hollow-core fibre (not shown here).
关键词： Non-invasive,Hollow-core,Real-time,Characterization,Whispering Gallery Mode Spectroscopy,Photonic Crystal Fibres
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM) - Hong Kong, China (2019.7.8-2019.7.12)] 2019 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM) - Hardware-in-the-Loop-Simulation of the light distribution of automotive Matrix-LED-Headlights*
摘要： This contribution proposes a novel Hardware-in-the-Loop (HiL)-simulation of the light distribution of matrix-headlights to reduce the duration and number of real night test drives. After calibration machine vision cameras measure and digitize the light distribution of the real matrix-headlight in the lab. The calibration process compares the light distribution measured by the camera with the absolute intensity-data from a goniophotometer. Minimizing the error determines the optimal transformation parameters. A virtual testing simulation visualizes the digitized light distribution under consideration of the actual driving dynamics. The HiL-simulation generates the control data for the real headlight. The evaluation of the approach uses a real matrix-headlight with 84 pixels and its measured intensity distribution as the reference. The system is real-time capable and the light distribution in the simulation matches the original headlight in intensity and color.
关键词： light distribution,matrix-headlights,simulation,Hardware-in-the-Loop,real-time
更新于2025-09-11 14:15:04
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[IEEE 2018 4th International Conference on Frontiers of Signal Processing (ICFSP) - Poitiers, France (2018.9.24-2018.9.27)] 2018 4th International Conference on Frontiers of Signal Processing (ICFSP) - Real Time Finger Typing Recognition on iPhone’s RGB Camera
摘要： Recently, information processing capability has improved. Many softwares using cameras have increased, and the image processing can be performed in real time. The Original Character Input System proposed this real time composed of a character input system for the iPad application. Is a method of touching the tablet screen with five fingers and inputting characters with different combinations. The system proposed this real time picture taking of a finger typing on the camera of the smartphone then recognizes the typing fingertip in real time with the characters being inputted. As a result of the verification of the iPhone 8, the system can be processed with 30 FPS when the captured image with the size of 640 x 480 and the CPU usage rate of approximately 95%. In addition, the recognition rate for each finger typing is 100%.
关键词： real time,finger recognition,segmentation,iPhone
更新于2025-09-11 14:15:04
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Efficient calculation of (resonance) Raman spectra and excitation profiles with real-time propagation
摘要： We investigate approaches for the calculation of (resonance) Raman spectra in a real-time time-dependent density functional theory (RT-TDDFT) framework. Several short time approximations to the Kramers, Heisenberg, and Dirac polarizability tensor are examined with regard to the calculation of resonance Raman spectra: One relies on a Placzek type expansion of the electronic polarizability and the other one relies on the excited state gradient method. The first one is shown to be in agreement with an approach based on perturbation theory in the case of a weak δ-pulse perturbation. The latter is newly applied in a real time propagation framework, enabled by the use of Pad′e approximants to the Fourier transform which allow for a sufficient resolution in the frequency domain. An analysis of the performance of Pad′e approximants is given. All approaches were found to be in good agreement for uracil and R-methyloxirane. Moreover it is shown how RT-TDDFT can be used to calculate Raman excitation profiles efficiently.
关键词： Raman spectra,Pad′e approximants,excitation profiles,time-dependent density functional theory,real-time propagation
更新于2025-09-10 09:29:36