Determination of director distributions in liquid crystal polymer-films bymeans of generalized anisotropic ellipsometry

We report on how to achieve and measure director tilt angle distributions t heta(z) in cross-linked nematic liquid crystal polymer (LCP) films by means of generalized anisotropic ellipsometry. LCP-alignment is made by linearly photopolymerized (LPP)-photo-alignment of LCP films on single substrates. For the first time arbitrary tilt angle distributions are achieved and expe rimentally verified. It is shown that not only the birefringence hn of nove l LCP-materials, which exhibit values up to Delta n = 0.4, but also the til t distribution theta(z) of the LC director can be varied. theta(z) is shown to be tunable between substrate surface and LCP/air interface over the ent ire range 90 degrees greater than or equal to theta z 0 degrees. The contro l of the tilt distribution in thin LCP-films on single substrates is essent ial for many applications, for instance in LPP/LCP wide-view films designed to increase the field of view of liquid crystal displays (LCDs).