This report forms a part of the systematic investigation on the imaging behaviour of a birefringent lens sandwiched between two linear polarizers. Since an appreciable amount of light energy is absorbed in the polarizers, an analytical formula for the light throughput of the proposed system has been developed. A comparative study of the performance of the said system with an isotropic lens of reduced size which give equal light levels at the output side has been performed.

S SANYAL

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

Light Throughput of a Birefringent Lens a: Comparative Study

Journal of Optics (India)

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 factor of encircled energy (FEE) in the diffraction pattern formed by an optical system consisting of an aberration-free birefringent lens sandwiched between two linear polarizers is computed directly from the optical transfer function (OTF) of the system. FEE curves are given showing the variation of image quality of the proposed system at the Gaussian Image plane and other observation planes with the birefringent lens parameters and the azimuthal settings of the transmission axes of the polarizers. The performance is compared to that of an ideal conventional glass lens. © 2003 Society of Photo-Optical Instrumentation Engineers.

Image assessment of a birefringent lens based on the factor of encircled energy

The Strehl definition along the axis of a birefringent lens sandwiched between two polarizers is studied analytically. The optic axis of the birefringent lens made of a uniaxial crystal is perpendicular to the lens axis, and the system behaves like a bifocus lens for proper orientation of the polarizers. The Sparrow criterion is employed for designing an imaging system with high depth of focus. It is shown that, when the two foci are separated by the Sparrow limit of resolution, the focal depth is maximum and the intensity point-spread function remains almost identical within this limit. The resolution according to the Rayleigh criterion in this zone is more than that of an ideal lens. © 2000 Optical Society of America.

High focal depth with a quasi-bifocus birefringent lens

The imaging characteristics of a birefringent lens sandwiched between two polarizers is studied analytically. If the optic axis of the birefringent crystal is perpendicular to the lens axis, the system behaves as a bifocal lens for proper orientations of the polarizers. It is shown that the proposed system can be adapted either for apodization or for super-resolution simply by rotating either of the two polarizers. It has greater depth of focus than conventional systems, as is evident from the results obtained. Expressions are obtained for the point spread function of such a system. Some specific cases are illustrated graphically. © 1998 Society of Photo-Optical Instrumentation Engineers.

Journal	Journal of Optics (India)
Publisher	Optical Society of India
ISSN	0970-0374