Wide area mapping of liquid crystal devices with passive and active command layers

Abstract

We track the non-uniformity of a wide area liquid crystal device using multiple cross-polarized intensity measurements. They give us not only accurate estimates of the core physical liquid crystal parameters, such as elastic constants, but also spatial maps of the device properties, including the liquid crystal thickness and pretilt angle. A bootstrapping statistical analysis, coupled with the multiple measurements, gives us reliable error bars on all the measured parameters.

Two-dimensional snapshot measurement of surface variation of anchoring in liquid crystal cells

“…The experiment is fully managed by a MATLAB code [40,41], which controls the measuring apparatus, data acquisition and performs the data analysis using the model described in Section 2 [30]. OMPA collects pointwise data across the cell and fits the elastic constants, the pretilt angle, the anchoring energy, and the cell thickness.…”

“…The strength of the model for the characterisation lies in its integrated, comprehensive approach to simultaneously extract the main parameters. We model the LC alignment in the planar nematic cell using the Frank-Oseen theory [30,32]. We neglect the LC fluid motion, since only smoothly varying high-frequency voltages are applied to the LC when measuring the CPI.…”

“…In this paper we build on our previous work [30,31] and extend it in two directions that are suitable to new LC devices and physics. First, we use the whole cell measurements to estimate the average polar anchoring energy.…”

Fast Method for Liquid Crystal Cell Spatial Variations Estimation Based on Modeling the Spectral Transmission

“…Therefore, it does not provide a full spectral and spatial characterization of the LCC. An additional method is to translate the LCC to perform measurements at different spatial locations and use prior information about the properties of the LCC for spatial variations estimation [11]. Another approach, given that the birefringence of the liquid crystal material is known, is to measure the cell gap at a single location by using a rotating polarizer method [12], or a rotating quarter-wave retarder method [13].…”

“…Additionally, it should be noted that one of the advantages of the presented method, is that in contrast to Refs. [11,12,13], it does not rely on prior information regarding the birefringence of the LCC in order to perform the ST spatial variations estimation.…”