Wollaston prism

noun

: a double-image compound prism producing two divergent beams of light plane-polarized at right angles to each other and consisting of two equal right-angled prisms of Iceland spar or quartz cemented along their long faces and so cut that in one the light passes along the optic axis and in the other at right angles to that axis

Word History

Etymology

after William H. Wollaston †1828

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