The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Nirmalya Ghosh - One of the best experts on this subject based on the ideXlab platform.
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quantitative fluorescence and elastic scattering tissue polarimetry using an eigenvalue calibrated spectroscopic mueller Matrix system
Optics Express, 2013Co-Authors: Jalpa Soni, Harsh Purwar, Harshit Lakhotia, Shubham Chandel, Chitram Banerjee, Uday Kumar, Nirmalya GhoshAbstract:A novel spectroscopic Mueller Matrix system has been developed and explored for both fluorescence and elastic scattering polarimetric Measurements from biological tissues. The 4 × 4 Mueller Matrix Measurement strategy is based on sixteen spectrally resolved (λ = 400 - 800 nm) Measurements performed by sequentially generating and analyzing four elliptical polarization states. Eigenvalue calibration of the system ensured high accuracy of Mueller Matrix Measurement over a broad wavelength range, either for forward or backscattering geometry. The system was explored for quantitative fluorescence and elastic scattering spectroscopic polarimetric studies on normal and precancerous tissue sections from human uterine cervix. The fluorescence spectroscopic Mueller matrices yielded an interesting diattenuation parameter, exhibiting differences between normal and precancerous tissues.
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quantitative fluorescence and elastic scattering tissue polarimetry using an eigenvalue calibrated spectroscopic mueller Matrix system
Optics Express, 2013Co-Authors: Jalpa Soni, Harsh Purwar, Harshit Lakhotia, Shubham Chandel, Chitram Banerjee, Uday Kumar, Nirmalya GhoshAbstract:A novel spectroscopic Mueller Matrix system has been developed and explored for both fluorescence and elastic scattering polarimetric Measurements from biological tissues. The 4 × 4 Mueller Matrix Measurement strategy is based on sixteen spectrally resolved (λ = 400 - 800 nm) Measurements performed by sequentially generating and analyzing four elliptical polarization states. Eigenvalue calibration of the system ensured high accuracy of Mueller Matrix Measurement over a broad wavelength range, either for forward or backscattering geometry. The system was explored for quantitative fluorescence and elastic scattering spectroscopic polarimetric studies on normal and precancerous tissue sections from human uterine cervix. The fluorescence spectroscopic Mueller matrices yielded an interesting diattenuation parameter, exhibiting differences between normal and precancerous tissues.
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development and eigenvalue calibration of an automated spectral mueller Matrix system for biomedical polarimetry
Proceedings of SPIE, 2012Co-Authors: Harsh Purwar, Jalpa Soni, Harshit Lakhotia, Shubham Chandel, Chitram Banerjee, Nirmalya GhoshAbstract:We present a novel spectral Mueller Matrix Measurement system for both elastic and inelastic scattering (fluorescence) polarimetric Measurements. The system comprises of a Xenon lamp as excitation source, a polarization state generator (PSG) and a polarization state analyzer (PSA) unit to generate and analyze polarization states required for 4 x 4 sample Mueller Matrix Measurements, coupled to a spectrometer for spectrally resolved (λ ~ 400 - 800 nm) signal detection. The PSG unit comprises of a fixed linear polarizer (polarization axis oriented at horizontal position) followed by a rotatable broadband quarter wave plate. The sample-scattered light is collected and collimated using an assembly of lenses, then passes through the PSA unit, and is finally recorded using the spectrometer. The PSA unit essentially consists of a similar arrangement as that of the PSG, but positioned in reverse order, and with the axis of the linear polarizer oriented at vertical position. A sequence of sixteen Measurements are performed by changing the orientation of the fast axis of the quarter wave plates of the PSG unit (for generating the four required elliptical polarization states) and that of the PSA unit (for analyzing the corresponding polarization states). The orientation angles (35°, 70°, 105° and 140°) were chosen based on optimization of the PSG and PSA matrices to yield most stable system Mueller matrices. The performance of the polarimeter was calibrated using Eigenvalue calibration method which also yielded the actual values of the system PSG and PSA matrices at each wavelength. The system has been automated and is capable of Mueller Matrix Measurement with high accuracy over the entire spectral range 400 - 800 nm (elemental error < 0.01). For recording the elastic scattering Mueller Matrix of sample, the PSG and PSA matrices for each wavelength are used, while for fluorescence Mueller Matrix Measurements, the PSG for the excitation wavelength (chosen to be 405 nm) and PSA for varying emission wavelengths (450 - 800 nm) are used. The developed spectral Mueller Matrix system has been initially used to record both elastic scattering and fluorescence Mueller matrices from normal and cancerous cervical tissues.
Jalpa Soni - One of the best experts on this subject based on the ideXlab platform.
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quantitative fluorescence and elastic scattering tissue polarimetry using an eigenvalue calibrated spectroscopic mueller Matrix system
Optics Express, 2013Co-Authors: Jalpa Soni, Harsh Purwar, Harshit Lakhotia, Shubham Chandel, Chitram Banerjee, Uday Kumar, Nirmalya GhoshAbstract:A novel spectroscopic Mueller Matrix system has been developed and explored for both fluorescence and elastic scattering polarimetric Measurements from biological tissues. The 4 × 4 Mueller Matrix Measurement strategy is based on sixteen spectrally resolved (λ = 400 - 800 nm) Measurements performed by sequentially generating and analyzing four elliptical polarization states. Eigenvalue calibration of the system ensured high accuracy of Mueller Matrix Measurement over a broad wavelength range, either for forward or backscattering geometry. The system was explored for quantitative fluorescence and elastic scattering spectroscopic polarimetric studies on normal and precancerous tissue sections from human uterine cervix. The fluorescence spectroscopic Mueller matrices yielded an interesting diattenuation parameter, exhibiting differences between normal and precancerous tissues.
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quantitative fluorescence and elastic scattering tissue polarimetry using an eigenvalue calibrated spectroscopic mueller Matrix system
Optics Express, 2013Co-Authors: Jalpa Soni, Harsh Purwar, Harshit Lakhotia, Shubham Chandel, Chitram Banerjee, Uday Kumar, Nirmalya GhoshAbstract:A novel spectroscopic Mueller Matrix system has been developed and explored for both fluorescence and elastic scattering polarimetric Measurements from biological tissues. The 4 × 4 Mueller Matrix Measurement strategy is based on sixteen spectrally resolved (λ = 400 - 800 nm) Measurements performed by sequentially generating and analyzing four elliptical polarization states. Eigenvalue calibration of the system ensured high accuracy of Mueller Matrix Measurement over a broad wavelength range, either for forward or backscattering geometry. The system was explored for quantitative fluorescence and elastic scattering spectroscopic polarimetric studies on normal and precancerous tissue sections from human uterine cervix. The fluorescence spectroscopic Mueller matrices yielded an interesting diattenuation parameter, exhibiting differences between normal and precancerous tissues.
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development and eigenvalue calibration of an automated spectral mueller Matrix system for biomedical polarimetry
Proceedings of SPIE, 2012Co-Authors: Harsh Purwar, Jalpa Soni, Harshit Lakhotia, Shubham Chandel, Chitram Banerjee, Nirmalya GhoshAbstract:We present a novel spectral Mueller Matrix Measurement system for both elastic and inelastic scattering (fluorescence) polarimetric Measurements. The system comprises of a Xenon lamp as excitation source, a polarization state generator (PSG) and a polarization state analyzer (PSA) unit to generate and analyze polarization states required for 4 x 4 sample Mueller Matrix Measurements, coupled to a spectrometer for spectrally resolved (λ ~ 400 - 800 nm) signal detection. The PSG unit comprises of a fixed linear polarizer (polarization axis oriented at horizontal position) followed by a rotatable broadband quarter wave plate. The sample-scattered light is collected and collimated using an assembly of lenses, then passes through the PSA unit, and is finally recorded using the spectrometer. The PSA unit essentially consists of a similar arrangement as that of the PSG, but positioned in reverse order, and with the axis of the linear polarizer oriented at vertical position. A sequence of sixteen Measurements are performed by changing the orientation of the fast axis of the quarter wave plates of the PSG unit (for generating the four required elliptical polarization states) and that of the PSA unit (for analyzing the corresponding polarization states). The orientation angles (35°, 70°, 105° and 140°) were chosen based on optimization of the PSG and PSA matrices to yield most stable system Mueller matrices. The performance of the polarimeter was calibrated using Eigenvalue calibration method which also yielded the actual values of the system PSG and PSA matrices at each wavelength. The system has been automated and is capable of Mueller Matrix Measurement with high accuracy over the entire spectral range 400 - 800 nm (elemental error < 0.01). For recording the elastic scattering Mueller Matrix of sample, the PSG and PSA matrices for each wavelength are used, while for fluorescence Mueller Matrix Measurements, the PSG for the excitation wavelength (chosen to be 405 nm) and PSA for varying emission wavelengths (450 - 800 nm) are used. The developed spectral Mueller Matrix system has been initially used to record both elastic scattering and fluorescence Mueller matrices from normal and cancerous cervical tissues.
Amir Polak - One of the best experts on this subject based on the ideXlab platform.
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tracer diffusion from a horizontal fracture into the surrounding Matrix Measurement by computed tomography
Journal of Contaminant Hydrology, 2003Co-Authors: Amir Polak, Abraham S Grader, Rony Wallach, Ronit NativAbstract:Abstract The vertical diffusion of NaI solution from a horizontal fracture into and within the surrounding Matrix was tracked and quantified over time using an artificially fractured chalk core (30×5 cm) and a second-generation X-ray computed tomography (CT) scanner. The different tracer-penetration distances imaged in the Matrix above and below the horizontal fracture are indicative of a greater tracer mass penetrating into the lower Matrix. The enhanced transport in the Matrix below the fracture was related to the Rayleigh–Darcy instability induced by the density differences between the heavier tracer solution in the fracture (1.038) and the distilled water that had initially resided in the Matrix. Our observations suggest that below the fracture, the tracer is propagated by an advection–diffusion process that is characterized by both higher rates and higher concentrations relative to its propagation by diffusion above the fracture. The experimental results suggest that the prediction of contaminant migration in a rock intersected by both vertical and horizontal (e.g. along bedding planes) fractures is difficult because of density effects that result in different solute-penetration rates.
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chemical diffusion between a fracture and the surrounding Matrix Measurement by computed tomography and modeling
Water Resources Research, 2003Co-Authors: Amir Polak, Abraham S Grader, Rony Wallach, Ronit NativAbstract:[1] A medical-based X-ray CT scanner was used to monitor the diffusion of NaI into the Matrix of a 20-cm-long, 5-cm diameter fractured chalk core. The core was retrieved from a core hole at a depth of 18.3 m and was artificially fractured along its axis using a Brazilian-like test. The NaI solution flowed continuously along the vertically oriented fracture and the transient lateral concentration distribution within the Matrix at different cross sections along the core was monitored by two-dimensional 2-mm-thick slices through the sample and an in-plan pixel resolution of about 0.25 mm. The lateral concentration distribution within the Matrix was characterized by a sharp decrease at a thin Matrix layer adjacent to the fracture/Matrix interface followed by diffusion-type concentration distribution elsewhere. This concentration variation suggests that a thin transition layer exists along the fracture/Matrix interface where the diffusion coefficient is higher than that of the bulk Matrix. The higher diffusion coefficient of the transition layer is possibly related to minifissures that develop when fractures are formed. After 6 days of tracer injection into the fracture inlet, distilled water was injected for 11 days, forming a reverse concentration gradient and back diffusion. A mathematical model that assumes diffusion within the Matrix and a linear concentration variation through the transition layer from its value in the fracture to its time-dependent value at the transition layer/Matrix interface was developed. Very good agreement was obtained between the predicted and measured concentrations during both the diffusion and back diffusion phases. Application of the model to a field site in the Negev desert, Israel, suggested that the rock Matrix that had been subjected to 20 year of contaminant diffusion would require more than 200 years before it would stop releasing contaminants into the intersecting fractures (a parabolic process). According to these calculations, remediation efforts based on clean water injection into the fractures are not feasible.
Xuesong Wang - One of the best experts on this subject based on the ideXlab platform.
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Influence of the frequency deviation on the simultaneous polarisation scattering Matrix Measurement
The Journal of Engineering, 2019Co-Authors: Qiao-ling Liu, Chen Pang, Xuesong WangAbstract:Based on a pair of linear frequency modulation waveforms with opposite slopes, the mathematical model of the influence of intermediate frequency deviation (IFD) and sampling frequency deviation (SFD) on simultaneous polarisation Measurement is derived. An IFD and SFD joint estimation and calibration method is proposed in this article. Simulation and real data results show that the radar frequency stability can change the position and phase of the polarisation scattering Matrix (PSM) Measurement. The approach proposed in this article can regulate the peak deviation effectively, compensate the phase error and accurately acquire the four elements of PSM.
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Moving Target Scattering Matrix Measurement Using the Three Polarizations Scheme
IEEE Geoscience and Remote Sensing Letters, 2019Co-Authors: Yong Yang, Xuesong WangAbstract:For classical alternate Measurement schemes, the motion of the target during polarization switching introduces additional phase errors in measuring the polarization scattering Matrix (PSM). In this letter, we address the moving target PSM Measurement problem by alternately transmitting three polarizations (3-Pol). We fully discuss the problem, including 3-Pol generation, the optimal polarization selection, and the corresponding PSM estimation, as a complete Measurement approach. This Measurement approach is robust to different PSMs, and its performance is not affected by the movement of the target. Compared with the classical schemes, this approach will benefit a 13-dB signal-to-noise ratio (SNR) increase for targets with small cross-polar components. Furthermore, when the SNR is greater than 15 dB, the mean of the polarized correlation coefficients is higher than 0.95. Conclusions presented in this letter are validated by the experimental results.
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Effects of wideband waveforms on simultaneous scattering Matrix Measurement of manoeuvring targets
IET Radar Sonar & Navigation, 2019Co-Authors: Qiao-ling Liu, Chen Pang, Xuesong WangAbstract:Both polarimetry and Doppler characteristics can be employed in remote sensing applications. Doppler information provides insight into the dynamic properties of radar targets, and polarimetry is associated with the intrinsic attributes of targets. Determining how to obtain accurate polarisation Measurements from Doppler information has been a concern. For high-speed targets, the relativistic effect on radar wideband echoes may be notable. With the conventional matched filter, this scale effect may produce significant amplitude and phase errors between two columns of the polarisation scattering Matrix (PSM), except for signal-to-noise ratio (SNR) loss. On the basis of the Taylor series expansion, the amplitude and phase expressions are derived in this study. Theoretical analysis shows that the amplitude and phase errors are related to the time–frequency allocation of the orthogonal waveforms and that the accuracy of the PSM is more susceptible to scale factors using frequency modulation waveforms than phase-coded waveforms. To suppress these amplitude and phase errors, a compensation method is proposed for orthogonal linear frequency modulation signals. Furthermore, the performances of the SNR loss and the velocity error effect are given. Finally, some numerical experimental results are provided to illustrate the effectiveness of the compensation.
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Matrix Measurement Method Based on Antenna Spatial Polarization Characteristics
Spatial Polarization Characteristics of Radar Antenna, 2018Co-Authors: Huanyao Dai, Xuesong Wang, Shunping Xiao, Hong Xie, Jia LuoAbstract:Radar target polarization Measurement is a basic problem in the field of radar polarization technology. How to acquire polarization information is undoubtedly a basic problem in the investigation of the radar detection technology.
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spatial polarization characteristics and scattering Matrix Measurement of orthogonal polarization binary array radar
Science in China Series F: Information Sciences, 2010Co-Authors: Huanyao Dai, Xuesong Wang, Jia Luo, Shunping XiaoAbstract:Polarimetry is an important trend in the development of modern radar. The technique for measuring polarization scattering property of the target is the key for polarization radar realization, but it faces challenges in engineering. Here, a new theoretical model for target scattering characteristic Measurement radar, named orthogonal polarization binary array radar (OPBAR), is proposed. The spatial polarization characteristics of the radar antennas are addressed. A new polarimetric algorithm that needs only one channel is designed. The polarization scattering Matrix Measurement can be implemented by processing received signal in a short time interval while antenna’s beam mechanically scans the target. Through compactness field microwave dark room experiment, measurments of dynamic broadband polarimetry on OPBAR have been conducted and the validity of research work has been demonstrated. The result is helpful to exploiting the capability of current radar systems and enhancing their information acquiring and processing capacity.
Li Xuan - One of the best experts on this subject based on the ideXlab platform.
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Improve the accuracy of interaction Matrix Measurement for liquid-crystal adaptive optics systems
Optics Express, 2014Co-Authors: Xingyun Zhang, Dayu Li, Lifa Hu, Quanquan Mu, Li XuanAbstract:We present a novel method to measure the interaction Matrix of liquid-crystal adaptive optics systems, by applying least squares method to mitigate the impact of Measurement noise. Experimental results showed a dramatic gain in the accuracy of interaction Matrix, and a considerable improvement in image resolution with open loop adaptive optics correction. (C)2014 Optical Society of America
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improve the accuracy of interaction Matrix Measurement for liquid crystal adaptive optics systems
Optics Express, 2014Co-Authors: Xingyun Zhang, Zhaoliang Cao, Li XuanAbstract:We present a novel method to measure the interaction Matrix of liquid-crystal adaptive optics systems, by applying least squares method to mitigate the impact of Measurement noise. Experimental results showed a dramatic gain in the accuracy of interaction Matrix, and a considerable improvement in image resolution with open loop adaptive optics correction.
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Modal interaction Matrix Measurement for liquid-crystal corrector: precision evaluation
Optics Express, 2009Co-Authors: Quanquan Mu, Xinghai Lu, Lifa Hu, Zenghui Peng, Li XuanAbstract:A modal interaction Matrix (IM) Measurement procedure is introduced for a liquid-crystal (LC) corrector for use in a phase-wrapping technique. Zernike modes are used to reconstruct the aberration wavefront and to drive the LC corrector. Usually the driving area is different from the active area. This difference induces a coupling effect on Zernike modes, which may have an impact on correction precision. In this paper the coupling effect is evaluated due to area difference and decentration, respectively. Then, a simulated turbulence wavefront is used to simulate the reconstruction process to evaluate its influence on reconstruction precision. We present simulation results that show that this method can be used to measure the IM with very high reconstruction precision under proper configuration. In order to maintain precision, the permissible eccentricity distance is also simulated with a result of no more than 5% of the LC corrector diameter.
