Opto-electrically and electro-optically controllable diaphragm aperture in a poly(N-vinylcarbazole) film-coated tandem-90°-twisted nematic liquid crystal cell

The opto-electrically and electro-optically controllable diaphragm aperture in a poly(N-vinylcarbazole) (PVK) film-coated tandem-90°-twisted nematic liquid crystal (TNLC) cell is investigated. The tandem-90°-TNLC cell assembled by two common 45°-TNLC cells can be adopted for incident linearly polarized lights at any linear polarization direction. The variations of diaphragm aperture made by a PVK film-coated tandem-90°-TNLC cell are demonstrated opto-electrically and electro-optically. The differences in the degree of linear polarization between the tandem-90°-TNLC and single-90°-TNLC cells for demonstrating diaphragm apertures are investigated. The dynamic transmittance, related to orientation of LCs resulting from the built-in electric fields induced by the diffused positive and negative ions in LC bulk, the induced electric fields generated by the diffused ions in LC bulk and conductive PVK films, and the ion-moving induced force, of the PVK film-coated tandem-90°-TNLC cell is studied, and the possible mechanism based on dynamic distribution of ions (impurities) in LC bulk is also proposed. The proposed mechanism of the dynamic transmittance phenomenon can be a useful reference to the developments of other PVK film-coated LC cells. Moreover, the PVK film-coated tandem-90°-TNLC cell can be considered a controllable diaphragm aperture shutter if the above ion-induced issues are overcome.