Mauguin was the first to notice that when he sandwiched the semi-solid liquid crystals between two aligned polarizers, he could twist them in relation to each other, but the light continued to be transmitted. This phenomena is called Mauguin regime (waveguide regime) in twisted nematic effect  .
^Mauguin, C.: Sur les cristaux liquides de Lehman. Bull. Soc. Fr. Miner. 34, 71–117 (1911)
^Blinov L.M. Structure and Properties of Liquid Crystals (Springer, 2011), pp. 439. ISBN 978-90-481-8828-4 Chapter 11.