Moiré pattern, produced by the overlapping of two radially sheared beams emerging from two longitudinally shifted focal points of a birefringent lens has been experimentally demonstrated. Coherent and incoherent Moiré patterns are generated with and without analyzer. Birefringent samples like mica sheets with opposite crystal axis to that of the birefringent lens modulate the Moiré pattern. Mica sheet of different thicknesses have been used to demonstrate the effect of thickness on phase retardation, hence on fringe pattern. Experimentally birefringence has been calculated by fringe analysis and compared with theoretically simulated birefringence. © 2015 Copyright SPIE.

J BANERJEE

M BERA

M RAY

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

Modulation of Moiré pattern using birefringent sample

Proceedings of SPIE - The International Society for Optical Engineering

A confocal microscopic setup with a pair of birefringent lenses having their crystal axes crossed is used to measure birefringence of thin samples. The method can be used to measure phase down to the order of λ/10. The fast and slow axes of the object also can be identified. The principle of the method along with the experimental setup is described. Some first-order experimental results are also presented. © 2008 Society of Photo-Optical Instrumentation Engineers.

Optical Engineering

Birefringence measurement using a confocal setup with a pair of birefringent lenses

A method for studying the stress-induced birefringence over the area of a sample by simultaneous application of shearing interferometry and moire techniques is dealt with. This is a method by which one can have the fringe pattern for the first and second derivative of the birefringence distribution in the form of the slope and curvature of the test wavefront. There is, however, a method of obtaining the second derivative fringe system by using a four- exposure holographic technique in which the pattern is generated by shearing of two holograms of deformed surface. This is related to stress distribution in the structure under test. In the presented method, on the other hand, the test wavefront carries the information of stress distribution in terms of birefringence. The suggested experimental setup can provide the slope and curvature of the test wavefront in a single exposure.

Journal	Data powered by TypesetProceedings of SPIE - The International Society for Optical Engineering
Publisher	Data powered by TypesetSPIE
ISSN	0277-786X