Biswajit Chakraborty

Bio: Biswajit Chakraborty is an academic researcher from University of Calcutta. The author has contributed to research in topics: Birefringence & Achromatic lens. The author has an hindex of 6, co-authored 33 publications receiving 110 citations. Previous affiliations of Biswajit Chakraborty include Yahoo!.

Process-integrated steel ladle monitoring, based on infrared imaging – a robust approach to avoid ladle breakout

Abstract: Ladle breakout is a risky affair which is always present in steel making. The ladle breakout involves equipment damage and loss of production and sometimes loss of life. The present article describ...

Depolarizing effect of propagation of a polarized polychromatic beam through an optically active medium: a generalized study

Abstract: The degree of polarization of a polarized polychromatic beam decreases during the passage of the beam through an optically active medium. In a previous paper [ B. Chakraborty A. K. Chakraborty , J. Phys. D18, 145 ( 1985)], this depolarizing effect in the case of a linearly polarized polychromatic beam having a flat-topped spectral profile was studied. In the present paper the effect of propagation of an elliptically polarized polychromatic beam having a Gaussian spectral profile through an optically active medium is studied. The results of the previous paper can be obtained as a particular case of this generalized study.

The Translation Groups as Generators of Gauge Transformation in B$\wedge$F Theory

Abstract: The translation group T(2), contained in Wigner's little group for massless particles, is shown to generate gauge transformations in the Kalb-Ramond theory, exactly as happens in Maxwell case. For the topologically massive ($B\wedge$F) gauge theory, both T(2) and T(3), act as the corresponding generators.

The effect of propagation of a polarised polychromatic beam through an optically active medium

Abstract: If a polarised polychromic beam passes through an optically active medium, a rotatory dispersion results. This dispersion effect is generally associated with a decrease of the degree of polarisation of the polychromatic beam. In the present article, this depolarising effect of a rotator has been studied in the cases of polychromatic beams having a flat-top spectral profile.

Spectral distances on the doubled Moyal plane using Dirac eigenspinors

Abstract: We present here a novel method of computing spectral distances in doubled Moyal plane in a noncommutative geometrical framework using Dirac eigen-spinors, while solving the Lipschitz ball condition explicitly through matrices. The standard results of longitudinal, transverse and hypotenuse distances between different pairs of pure states have been computed and Pythagorean equality between them have been re-produced. The issue of non-unital nature of Moyal plane algebra is taken care of through a sequence of projection operators constructed from Dirac eigen-spinors, which plays a crucial role throughout this paper. At the end, a toy model of "Higgs field" has been constructed by fluctuating the Dirac operator and the variation on the transverse distance has been demonstrated, through an explicit computation.

Quantum Theory of Fields

Abstract: To say that this is the best book on the quantum theory of fields is no praise, since to my knowledge it is the only book on this subject But it is a very good and most useful book The original was written in German and appeared in 1942 This is a translation with some minor changes A few remarks have been added, concerning meson theory and nuclear forces, also footnotes referring to modern work in this field, and finally an appendix on the symmetrization of the energy momentum tensor according to Belinfante Quantum Theory of Fields Prof Gregor Wentzel Translated from the German by Charlotte Houtermans and J M Jauch Pp ix + 224, (New York and London: Interscience Publishers, Inc, 1949) 36s

Polarimetric characterization of light and media - Physical quantities involved in polarimetric phenomena

Abstract: An objective analysis is carried out of the matricial models representing the polarimetric properties of light and material media leading to the identification and definition of their corresponding physical quantities, using the concept of the coherency matrix. For light, cases of homogeneous and inhomogeneous wavefront are analyzed, and a model for 3D polarimetric purity is constructed. For linear passive material media, a general model is developed on the basis that any physically realizable linear transformation of Stokes vectors is equivalent to an ensemble average of passive, deterministic nondepolarizing transformations. Through this framework, the relevant physical quantities, including indices of polarimetric purity, are identified and decoupled. Some decompositions of the whole system into a set of well-defined components are considered, as well as techniques for isolating the unknown components by means of new procedures for subtracting coherency matrices. These results and methods constitute a powerful tool for analyzing and exploiting experimental and industrial polarimetry. Some particular application examples are indicated.

Characteristic properties of Mueller matrices

Abstract: A complete and minimum set of necessary and sufficient conditions for a real 4×4 matrix to be a physical Mueller matrix is obtained. An additional condition is presented to complete the set of known conditions, namely, the four conditions obtained from the nonnegativity of the eigenvalues of the Hermitian matrix H associated with a Mueller matrix M and the transmittance condition. Using the properties of H, a demonstration is also presented of Tr(MTM)=4m002 as being a necessary and sufficient condition for a physical Mueller matrix to be a pure Mueller matrix.

Determination of the transfer function for optical surface topography measuring instruments—a review

Abstract: A significant number of areal surface topography measuring instruments, largely based on optical techniques, are commercially available. However,implementation of optical instrumentation into production is currently difficult dueto the lack of understanding of the complex interaction between the light and the component surface. Studying the optical transfer function of the instrument can help address this issue. Herea review is given of techniques for the measurement of optical transfer functions. Starting from the basis of a spatially coherent, monochromatic confocal scanning imaging system, the theory of optical transfer functions in three-dimensional (3D) imaging is presented. Further generalizations are reviewed allowing the extension of the theory to the description of conventional and interferometric 3D imaging systems. Polychromatic transfer functions and surface topography measurements are also discussed. Following presentation of theoretical results, experimental methods to measure the optical transfer function of each class of system are presented, with a focus on suitable methods for the establishment of calibration standards in 3D imaging and surface topography measurements.

Maximum spectral luminous efficacy of white light

Abstract: As lighting efficiency improves, it is useful to understand the theoretical limits to luminous efficacy for light that we perceive as white. Independent of the efficiency with which photons are generated, there exists a spectrally imposed limit to the luminous efficacy of any source of photons. We find that, depending on the acceptable bandpass and—to a lesser extent—the color temperature of the light, the ideal white light source achieves a spectral luminous efficacy of 250–370 lm/W. This is consistent with previous calculations, but here we explore the maximum luminous efficacy as a function of photopic sensitivity threshold, color temperature, and color rendering index; deriving peak performance as a function of all three parameters. We also present example experimental spectra from a variety of light sources, quantifying the intrinsic efficacy of their spectral distributions.