Abstract
Pretilt angle and cell thickness are two extremely important parameters in
predicting the behavior of vertically aligned negative nematic liquid
crystal (LC) displays. The accurate estimation of pretilt angle and cell
thickness is not a trivial task when these devices work in reflective mode,
as in liquid crystal on silicon (LCOS) vertically aligned nematic (VAN)
displays. Usual experimental setups are based on the proportionality between
the retardation of the polarization components of the incident light and the
product effective birefringence times thickness. However, any attempt to
separate the two product variables is cancelled out by symmetry from
reflection. This work shows a relatively simple method capable of separating
both variables, allowing accurate, independent measurements of pretilt and
thickness, as well as other configurations details, such as residual twist.
A simulation model based on the properties of actual reflective displays has
been developed. An experimental setup specifically designed for measuring
LCOS VAN cells has been prepared. Initial comparisons between experimental
measurements of intensity and theoretical results showed some discrepancies
that could be explained assuming that the LC profile contains a residual
twist from the manufacturing process. Including that twist in the model, an
excellent agreement between theory and experiment has been achieved.
Matching simulations and experimental results yield separate determinations
of pretilt angle and thickness, and give good estimates for the residual
twist angle.
© 2010 IEEE
PDF Article
More Like This
Cited By
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
Contact your librarian or system administrator
or
Login to access Optica Member Subscription