We study the intensity point spread function (IPSF) of a uniaxial birefringent lens sandwiched between two linear polarizers under broadband illumination having flat-top spectral profile. The optic axis of the birefringent crystal is perpendicular to the lens axis. For monochromatic input illumination, a low-power birefringent lens offers enhanced resolution under parallel-polarizers configuration and apodization under crossed-polarizers configuration with a single focus as well. At a relatively high value of birefringence parameter, the proposed system behaves as a double-focus lens. The present communication uses a novel technique to study the effect of polychromatic illumination on the imaging characteristics of birefringent lenses. The studies reveal that the imaging characteristics of the low-power birefrigent lens does not deteriorate considerably under polychromatic illumination. However, for a polychromatic beam with large bandwidth, the imaging behavior of the system having high birefringence parameter deviates appreciably from that under strictly monochromatic illumination. The said system even loses its inherent bi-focal nature due to depolarization of polarized polychromatic light upon passage through the birefringent crystal. © 2011 Elsevier GmbH.

S MANDAL

A GHOSH

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Optik

This paper reports the imaging characteristics of an optical system consisting of a lens made of a uniaxial birefringent crystal sandwiched between two linear polarizers under polychromatic input illumination. The optic axis of the birefringent crystal is perpendicular to the lens axis and for an initial investigation, the spectral profile of the input beam is considered to be uniform for all wavelengths. The study reveals that if the variation of the birefringence parameters of the device with the wavelength is less, a larger bandwidth may be used without considerably deviating from the imaging characteristics under strictly monochromatic illumination. The nonlinear variation of birefringence with wavelength results in an asymmetric axial irradiance distribution. This obviates an optimal operating wavelength as well as a proper choice of the lens material. It is found that no appreciable change in image quality under diffraction-limited condition results for an input beam having 632 nm operating wavelength and 60 nm bandwidth. Therefore, it may be feasible to use this system with a white light source in conjunction with a wavelength-selective filter. © 2006 Elsevier GmbH. All rights reserved.

Imaging characteristics of a birefringent lens under broadband illumination

We report the frequency response characteristics of an optical system consisting of a lens made of uniaxial birefringent crystal sandwiched between two linear polarizers; the lens has prespecified off-axis aberrations such as primary astigmatism and primary coma. An analytical expression is obtained for the optical transfer function of the proposed system by use of the autocorrelation of the pupil function over the lens aperture. Some specific cases are computed and illustrated graphically. It has been shown that the proposed system has imaging characteristics distinctly different from those of an ordinary glass lens, and these may be advantageous for better balancing of aberrations in conventional imaging systems. © 2004 Optical Society of America.

Applied Optics

Frequency response characteristics of a birefringent lens with off-axis aberrations

We report a systematic investigation on the imaging behavior of an optical system consisting of a lens made of a uniaxial birefringent crystal sandwiched between two linear polarizers with the introduction of prespecified off-axis aberrations such as astigmatism and coma. The intensity point spread function is used as the image assessment parameter. It has been shown that for a point object, the proposed system has higher tolerance to the presence of off-axis aberrations than an imaging system formed by an ordinary glass lens. Some specific cases are computed and illustrated graphically. © 2004 Society of Photo-Optical Instrumentation Engineers.

Optical Engineering

High tolerance to off-axis aberrations with a birefringent lens

The diffraction-based optical frequency response characteristic of a birefringent crystal lens sandwiched between two linear polarizers has been studied analytically using the autocorrelation of the pupil function over the lens aperture. The optical transfer function (OTF) of this proposed system depends on the material as well as design parameters of the crystal lens, along with the orientations of the transmission axes of the two polarizers relative to each other and to the optic axis of the birefringent lens. Naturally, the OTF of such a system can be varied at the lens fabrication stage like other lenses. An online variation of the OTF is also possible just by rotating any of the two polarizers included in the system. It has been shown that the proposed system can be adapted either for apodization or for super-resolution simply by rotating any of the two polarizers. This system may be designed for obtaining high depth of focus without significant image degradation, as well as for image processing operations like high frequency enhancement. The response of the system is studied at the Gaussian image plane as a function of the line frequencies in the object for different values of the birefringent lens parameters, and also for two different settings of the analyzer. The results are compared with the response of an ideal lens. © 2002 Society of Photo-Optical Instrumentation Engineers.

Frequency response characteristics of a birefringent lens

We report a systematic investigation of the imaging behavior of an optical system consisting of a lens from a uniaxial birefringent crystal sandwiched between two linear polarizers into which primary spherical aberration has been introduced. The proposed system has higher tolerance to primary spherical aberration and has a larger depth of focus than an imaging system found with an isotropic lens. Some specific cases are computed and illustrated graphically. © 2002 Optical Society of America.

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ISSN	0030-4026