Tunable liquid crystal prism for differential interference contrast microscopy

Anatoli Murauski; Alexander Muravsky

doi:10.1117/12.3017494

19 June 2024 Tunable liquid crystal prism for differential interference contrast microscopy

Anatoli Murauski, Alexander Muravsky

Proceedings Volume 13016, Liquid Crystals Optics and Photonic Devices; 130160M (2024) https://doi.org/10.1117/12.3017494
Event: SPIE Photonics Europe, 2024, Strasbourg, France

Abstract

Differential interference contrast (DIC) technique is an advanced tool of polarization microscopy applied for visualization of transparent refractive profiles and heights of complex objects. Based on utilization of special anisotropic prisms it is widely used in studies of biology, microelectronics and etc. Classical DIC prism comprises sub-prisms’ cuts of two quartz crystals with orthogonal optical axes. The cut angle is fixed to match to the single objective lens only, while prism operation requires precise mechanical translation. Thus traditional DIC microscopy is complex in implementation and rather expensive. We developed tunable liquid crystal (LC) prism suitable for direct replacement of DIC prism in existing optical designs. The unique tunability of LC allows omitting mechanical displacement and replacing it with electrical control. The elegant solution of LC DIC prism comprises two wedge LC cells and two pairs of electrodes for V1 and V2 voltage levels control. The cells have orthogonal azimuthal LC alignment to have a compensated birefringence zone in the middle of the wedge. Application of the base voltage level V to prism electrodes changes the DIC prism angle to match the selected objective lens. The tunable LC DIC prism is universal and capable to operate with different microscope objective lenses. Introduction of the small voltage difference allows to shift the position of compensated birefringent zone. Thus control of voltage levels at the DIC prism electrodes releases the need of precise mechanical translation. So mechanical translation can be omitted and replaced with digital-to-analog converter (DAC) outputs of low voltage microcontroller. Tunable liquid crystal DIC prism was fabricated and successfully tested in differential interference contrast mode of industrial polarizing microscope. Tunable LC prisms make DIC microscopy cost affordable, suitable for automation and integration into optical measurement systems.

Conference Presentation

Citation Download Citation

Anatoli Murauski and Alexander Muravsky "Tunable liquid crystal prism for differential interference contrast microscopy", Proc. SPIE 13016, Liquid Crystals Optics and Photonic Devices, 130160M (19 June 2024); https://doi.org/10.1117/12.3017494

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