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L. N. Hazra

Bio: L. N. Hazra is an academic researcher from University of Calcutta. The author has contributed to research in topics: Lens (optics) & Numerical integration. The author has an hindex of 2, co-authored 6 publications receiving 16 citations.

Papers
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Journal ArticleDOI
TL;DR: A systematic approach to study the feasibility of using singlets for the individual components by providing an analytical procedure to select the optimum glass in a semiautomatic manner and attempting to ascertain the practical viability of a singlet solution.
Abstract: It has been recently shown that the complex problem of thin lens structural design of a multicomponent lens system with a prespecified set of primary aberration residuals and Gaussian characteristics can be reduced to the problem of design of individual components with specified Gaussian parameters and central aberration targets. This paper reports a systematic approach to study the feasibility of using singlets for the individual components. The method provides an analytical procedure to select the optimum glass in a semiautomatic manner. It also attempts to ascertain the practical viability of a singlet solution by considering the possible effects of the structure of the singlet on higher-order aberrations. A set of graphs for rapid study of the feasibility of a singlet solution is also presented.

8 citations

Journal ArticleDOI
TL;DR: A new quadrature technique is presented that obviates the need for knowledge of derivatives of the argument of the exponential integrand in the calculation of image assessment critiera.
Abstract: The calculation of image assessment critiera, eg, the Strehl ratio, the point spread function, or the optical transfer function, involves the evaluation of an integral where the integrand is highly oscillatory over a large range of integration Prefaced with a brief description of the well-known numerical quadrature methods adopted for the purpose, this paper presents a new quadrature technique that obviates the need for knowledge of derivatives of the argument of the exponential integrand Some illustrative numerical results are presented

4 citations

Journal ArticleDOI
TL;DR: An analytical approach for the design of higher-order thick kinoform lenses for stigmatic imaging between extra-axial conjugate points is presented.
Abstract: A kinoform lens and its substrate are usually treated as two distinct components with a common interface. Thick kinoform lenses treat the relief profile and the substrate as an integrated component. An analytical approach for the design of higher-order thick kinoform lenses for stigmatic imaging between extra-axial conjugate points is presented. An illustrative example is given.

2 citations

Journal ArticleDOI
TL;DR: In this article, exact analytical expressions for the boundaries of individual zones of a zone plate that yields stigmatic imaging between two extraaxial conjugate points are presented, which can be used to obtain simple formulae for the two parameters.
Abstract: We present exact analytical expressions for the boundaries of individual zones of a zone plate that yields stigmatic imaging between two extraaxial conjugate points. Our treatment incorporates imaging at any order. It is found that the boundaries of the zones are elliptical and they are not concentric. We introduce dimensionless variables to arrive at convenient expressions for eccentricity and shift at the centre of the elliptical zone boundaries. Our approach enables us to obtain simple formulae for the two parameters. Approximations involved in the same are valid for most practical applications.

1 citations

Journal Article
01 Jan 1996-Optik
TL;DR: In this article, the exact analytical expressions for boundaries of the individual zones of a zone plate producing a stigmatic image of an extraaxial point at infinity were derived, and it was found that for a specific image point, the boundaries of all zones are elliptical having the same eccentricity.

1 citations


Cited by
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Journal ArticleDOI
TL;DR: A genetic algorithm is used in the structural design of cemented doublets in accordance with a prespecified set of Gaussian characteristics and primary aberration targets to explore the solution space in search of the global as well as useful local optima.
Abstract: The authors use a genetic algorithm in the structural design of cemented doublets in accordance with a prespecified set of Gaussian characteristics and primary aberration targets. Actual glasses are taken as variables. Suitable modifications in the algorithm are sought with which to explore the solution space in search of the global as well as useful local optima. Some illustrative examples of structural design are given.

32 citations

01 Jan 1989
TL;DR: In this article, the design, characterization, and test of X-ray/EUV multilayer optics and the design and characterization of grazing incidence X-rays were discussed.
Abstract: Topics included in these proceedings are on X-ray/EUV zone plates, filters, and windows; X-ray/EUV microscopes, telescopes, and monochromators; the design, characterization, and test of multilayer optics; the fabrication of X-ray/EUV multilayer optics; and the design, characterization, and test of grazing incidence X-ray optics. Other topics are on the fabrication of grazing incidence X-ray optics, X-ray/EUV space observatories and missions, the test and calibration of X-ray/EUV instruments, X-ray polarimetry, and X-ray/EUV spectroscopy and instruments. Papers are presented on 8-keV X-ray zone plates, a cylindrical X-ray multilayer monochromator, multilayer mirrors for 182 A, advanced flow polishing of exotic optical materials, and optical analysis of grazing incidence ring resonators for free-electron lasers. Attention is also given to X-ray mirrors for the European Synchrotron Radiation Facility, the XUV wide-field camera for Rosat, an optical test and alignment method for the XMM mirror module, Bragg crystal polarimeters, and a liftoff process for multilayer phase gratings.

29 citations

Dissertation
21 Mar 2016
TL;DR: In this paper, a chromatisch-kon-fokale system is described, in which the spektralen Kompenenten of the system are modelled.
Abstract: Chromatisch-konfokale Systeme fokussieren die spektralen Kompenenten eines polychromatischen Signals auf unterschiedliche raumliche Positionen, an denen sie mit Hilfe von Blenden gefiltert werden. Auf diese Weise konnen Informationen einerseits in der Spektralverteilung eines optischen Signals gespeichert werden. Anderseits kann auch die Spektralverteilung eines polychromatischen Signals ermittelt werden. Chromatisch-konfokale Systeme werden haufig zur beruhrungslosen Abstandsmessung und fur die ortsaufgeloste Spektroskopie eingesetzt. In dieser Arbeit werden Designstrategien fur chromatisch-konfokale Systeme entwickelt. Ein Schwerpunkt liegt auf der systematischen Modellierung der Signalentstehung unter Berucksichtigung der physikalischen Eigenschaften des optischen Systems, der Abbildungsfehler und der Eigenschaften des Detektionssystems. Hierbei werden insbesondere auch inkoharente Lichtquellen und raumlich ausgedehnte Beleuchtungsgeometrien berucksichtigt. Schnelle numerische Implementationen dieser Modelle erlauben in allen Stadien des Designprozesses eine Vorhersage des spektralen Filterverhaltens. Das spektrale Filterverhalten wird als primares Bewertungskriterium fur die Leistungsfahigkeit des optischen Systems verwendet und wird zur Ableitung effektiver Designstrategien herangezogen. Die Designstrategien umfassen sowohl die Entwicklung von Startsystemen als auch den nachfolgenden Optimierungsprozess, bei dem monochromatische Abbildungsfehler berucksichtigt werden. Der Fokus liegt hierbei insbesondere auf der nachtraglichen Korrektur der Abbildungsfehler wahrend der Signalverabeitung und auf ihrer automatischen Kompensation durch bestimmte Systemanordnungen. In Kombination mit den neu entwickelten Signalerzeugungsmodellen ermoglicht dieser Ansatz die Entwicklung optimierter, kompakter und gunstiger Sensorsysteme, die auf die Anforderungen des jeweiligen Anwendungsgebietes zugeschnitten sind und auf kostengunstigen Lichtquellen wie Leuchtdioden basieren. Die vorgestellten Designstrategien werden fur die Entwicklung verschiedener Demonstrator- und kommerzieller Sensorsysteme eingesetzt.

24 citations

Journal ArticleDOI
TL;DR: In this paper, an implementation of a genetic algorithm in the structural design of broken contact doublets according to a prespecified set of Gaussian characteristics and primary aberration targets is presented.
Abstract: This paper presents an implementation of a genetic algorithm in the structural design of broken contact doublets according to a prespecified set of Gaussian characteristics and primary aberration targets. The objective of this study is to investigate the effectiveness of the algorithm in finding out global as well as useful local optima and its dependence on some parameters characterizing the genetic operators. Actual glasses are taken as variables. Some illustrative examples are given.

21 citations

Journal ArticleDOI
TL;DR: The role of genetic diversity in the evolving population on convergence of the optimization runs has been investi- gated, and, accordingly suitable modifications are incorporated in the basic genetic algorithm to eliminate undue stagnation and premature convergence problems.
Abstract: We present an implementation of a genetic algorithm in the structural design of cemented triplets according to a prespecified set of Gaussian characteristics and primary aberration targets. The approach is directed toward obtaining a suite of promising solutions allowing some floating of the primary aberration targets. This method obviates the need for any heuristic preselection of glasses for the three elements of the triplet. Searches for optimal solutions are conducted in the total configu- ration space of the degrees of freedom, consisting of continuous vari- ables like shape factor and power distributions, and discrete variables like available glass types. The role of genetic diversity in the evolving population on convergence of the optimization runs has been investi- gated, and, accordingly suitable modifications are incorporated in the basic genetic algorithm to eliminate undue stagnation and premature convergence problems. Some illustrative examples are given. © 2004

18 citations