Mayank Kaushik - Academia.edu (original) (raw)
Papers by Mayank Kaushik
2011 Seventh International Conference on Intelligent Sensors, Sensor Networks and Information Processing, 2011
Terahertz spectroscopy has emerged as an important tool for identification and classification of ... more Terahertz spectroscopy has emerged as an important tool for identification and classification of materials, which exhibit absorption features at specific and distinct frequency bins in the THz spectrum. The scattering of terahertz radiation from granular substances can significantly distort the spectral fingerprint of the material under study. In this paper we propose a signal processing based technique to mitigate the
2011 IEEE International Conference on Signal Processing, Communications and Computing (ICSPCC), 2011
Abstract This paper presents a three dimensional sensor and source position calibration algorithm... more Abstract This paper presents a three dimensional sensor and source position calibration algorithm for automatically determining the positions of individual microphones in a three dimensional space with at least one linear sub array of sensors. Time-difference of arrival ...
35th International Conference on Infrared, Millimeter, and Terahertz Waves, 2010
Scattering is a major problem in precise measurement of quasi-optical parameters of material samp... more Scattering is a major problem in precise measurement of quasi-optical parameters of material samples. In this paper, we review some popular scattering mitigating techniques and propose a novel method that allows calculating true absorption spectra for samples with unknown thickness and granularity.
Journal of Applied Physics, 2012
Frequency dependent absorption by materials at distinct frequencies in the THz range is commonly ... more Frequency dependent absorption by materials at distinct frequencies in the THz range is commonly used as spectral-fingerprints for identification and classification. For transmission measurements, the substance under study is often mixed with a transparent host material. Refractive index variations arising from the presence of impurities and inconsistencies in the sample's internal structure often cause the incident radiation to scatter. This can significantly distort the measured spectral-fingerprints. In this letter, we present a numerical approach to allay the scattering contribution in THz-TDS measurements, provided the sample's refractive index is known, and reveal the true absorption spectra for a given sample. V C 2012 American Institute of Physics. [http://dx.
IEEE Photonics Technology Letters, 2000
The scattering of terahertz radiation from the granular nature of a sample can potentially distor... more The scattering of terahertz radiation from the granular nature of a sample can potentially distort or obscure its characteristic spectral features. Several techniques have been proposed to reduce the effects of scattering in terahertz timedomain spectroscopy (THz-TDS) measurements, that usually require a complex measurement apparatus or rely on specific information about the sample under study. However, in realworld applications a priori information of the sample is not always known and therefore the applicability of these techniques may be limited. In this letter, we present a method for estimating and mitigating scattering effects in THz-TDS measurements for samples made of material exhibiting sharp and sparse absorption features, without requiring information of its granularity, refractive index, and density.
Applied Physics Letters, 2012
Terahertz (THz) spectroscopy and imaging have emerged as important tools for identification and c... more Terahertz (THz) spectroscopy and imaging have emerged as important tools for identification and classification of various substances, which exhibit absorption characteristics at distinct frequencies in the THz range. The spectral fingerprints can potentially be distorted or obscured by electromagnetic scattering caused by the granular nature of some substances. In this paper, we present THz time domain transmission measurements of granular polyethylene powders in order to investigate an effective medium theory that yields a parameterized model, which can be used to estimate the empirical measurements to good accuracy. [doi:10.1063/1.3674289] In terahertz (THz) (or T-ray) time domain spectroscopy, the scattering of the broadband radiation within nonhomogeneous media, such as polycrystalline materials, is a major problem in that it can obscure the THz signal of interest. When the sizes of scattering centers become comparable to THz wavelengths, the scattering process can no longer be described by a simple Rayleigh scattering model but has to be modeled by a more complex approach.
Applied Physics Letters, 2012
Recent years have seen significant advances in material diagnostics and analysis using terahertz ... more Recent years have seen significant advances in material diagnostics and analysis using terahertz (THz) time domain spectroscopy (TDS) and imaging. Despite its widespread application, the interaction between THz radiation and materials with random structure is not yet fully studied. Separation of absorption and scattering is required to extract the true absorption spectra, thus enabling direct comparison with pure samples in a spectral data base for automated recognition. Here, we present a discrete wavelet transform based iterative reconstruction technique that reduces the scattering contribution in THz-TDS measurements, in composites with absorbing constituents that exhibit sharp absorption features. [http://dx.
Applied Physics Letters, 2012
Frequency dependent absorption of a given material at distinct frequencies in the terahertz (THz)... more Frequency dependent absorption of a given material at distinct frequencies in the terahertz (THz) range is commonly used as a spectral fingerprint for material identification and classification. However, in the presence of strong scattering, these features can often become distorted or altered. Thus, there is an important need to understand how scattering from a sample alters the THz signal. In this letter, we propose an iterative algorithm that builds on the effective field theory proposed by P. C. Waterman and R. Truell [J. Math. Phys. 2, 512-537 (1961)] and offers a rather simple and computationally efficient method for accurately explaining the multiple scattering response of a medium. V C 2012 American Institute of Physics. [http://dx.
2011 International Conference on Infrared, Millimeter, and Terahertz Waves, 2011
Scattering poses a major challenge to the precise measurement of spectral parameters of various m... more Scattering poses a major challenge to the precise measurement of spectral parameters of various materials. In this paper, we propose a novel signal processing based method of estimating scattering loss of a medium without precise information of its granularity, refractive index, and density.
2011 Seventh International Conference on Intelligent Sensors, Sensor Networks and Information Processing, 2011
Terahertz spectroscopy has emerged as an important tool for identification and classification of ... more Terahertz spectroscopy has emerged as an important tool for identification and classification of materials, which exhibit absorption features at specific and distinct frequency bins in the THz spectrum. The scattering of terahertz radiation from granular substances can significantly distort the spectral fingerprint of the material under study. In this paper we propose a signal processing based technique to mitigate the
2011 IEEE International Conference on Signal Processing, Communications and Computing (ICSPCC), 2011
Abstract This paper presents a three dimensional sensor and source position calibration algorithm... more Abstract This paper presents a three dimensional sensor and source position calibration algorithm for automatically determining the positions of individual microphones in a three dimensional space with at least one linear sub array of sensors. Time-difference of arrival ...
35th International Conference on Infrared, Millimeter, and Terahertz Waves, 2010
Scattering is a major problem in precise measurement of quasi-optical parameters of material samp... more Scattering is a major problem in precise measurement of quasi-optical parameters of material samples. In this paper, we review some popular scattering mitigating techniques and propose a novel method that allows calculating true absorption spectra for samples with unknown thickness and granularity.
Journal of Applied Physics, 2012
Frequency dependent absorption by materials at distinct frequencies in the THz range is commonly ... more Frequency dependent absorption by materials at distinct frequencies in the THz range is commonly used as spectral-fingerprints for identification and classification. For transmission measurements, the substance under study is often mixed with a transparent host material. Refractive index variations arising from the presence of impurities and inconsistencies in the sample's internal structure often cause the incident radiation to scatter. This can significantly distort the measured spectral-fingerprints. In this letter, we present a numerical approach to allay the scattering contribution in THz-TDS measurements, provided the sample's refractive index is known, and reveal the true absorption spectra for a given sample. V C 2012 American Institute of Physics. [http://dx.
IEEE Photonics Technology Letters, 2000
The scattering of terahertz radiation from the granular nature of a sample can potentially distor... more The scattering of terahertz radiation from the granular nature of a sample can potentially distort or obscure its characteristic spectral features. Several techniques have been proposed to reduce the effects of scattering in terahertz timedomain spectroscopy (THz-TDS) measurements, that usually require a complex measurement apparatus or rely on specific information about the sample under study. However, in realworld applications a priori information of the sample is not always known and therefore the applicability of these techniques may be limited. In this letter, we present a method for estimating and mitigating scattering effects in THz-TDS measurements for samples made of material exhibiting sharp and sparse absorption features, without requiring information of its granularity, refractive index, and density.
Applied Physics Letters, 2012
Terahertz (THz) spectroscopy and imaging have emerged as important tools for identification and c... more Terahertz (THz) spectroscopy and imaging have emerged as important tools for identification and classification of various substances, which exhibit absorption characteristics at distinct frequencies in the THz range. The spectral fingerprints can potentially be distorted or obscured by electromagnetic scattering caused by the granular nature of some substances. In this paper, we present THz time domain transmission measurements of granular polyethylene powders in order to investigate an effective medium theory that yields a parameterized model, which can be used to estimate the empirical measurements to good accuracy. [doi:10.1063/1.3674289] In terahertz (THz) (or T-ray) time domain spectroscopy, the scattering of the broadband radiation within nonhomogeneous media, such as polycrystalline materials, is a major problem in that it can obscure the THz signal of interest. When the sizes of scattering centers become comparable to THz wavelengths, the scattering process can no longer be described by a simple Rayleigh scattering model but has to be modeled by a more complex approach.
Applied Physics Letters, 2012
Recent years have seen significant advances in material diagnostics and analysis using terahertz ... more Recent years have seen significant advances in material diagnostics and analysis using terahertz (THz) time domain spectroscopy (TDS) and imaging. Despite its widespread application, the interaction between THz radiation and materials with random structure is not yet fully studied. Separation of absorption and scattering is required to extract the true absorption spectra, thus enabling direct comparison with pure samples in a spectral data base for automated recognition. Here, we present a discrete wavelet transform based iterative reconstruction technique that reduces the scattering contribution in THz-TDS measurements, in composites with absorbing constituents that exhibit sharp absorption features. [http://dx.
Applied Physics Letters, 2012
Frequency dependent absorption of a given material at distinct frequencies in the terahertz (THz)... more Frequency dependent absorption of a given material at distinct frequencies in the terahertz (THz) range is commonly used as a spectral fingerprint for material identification and classification. However, in the presence of strong scattering, these features can often become distorted or altered. Thus, there is an important need to understand how scattering from a sample alters the THz signal. In this letter, we propose an iterative algorithm that builds on the effective field theory proposed by P. C. Waterman and R. Truell [J. Math. Phys. 2, 512-537 (1961)] and offers a rather simple and computationally efficient method for accurately explaining the multiple scattering response of a medium. V C 2012 American Institute of Physics. [http://dx.
2011 International Conference on Infrared, Millimeter, and Terahertz Waves, 2011
Scattering poses a major challenge to the precise measurement of spectral parameters of various m... more Scattering poses a major challenge to the precise measurement of spectral parameters of various materials. In this paper, we propose a novel signal processing based method of estimating scattering loss of a medium without precise information of its granularity, refractive index, and density.