Browsing by Author "Raynes, Peter"

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High-brightness relaxed-bend state in a pi cell stabilized by synchronized polymerization
(2008-06-02)
Yang, Bo-Ru
;
Elston, Steve J.
;
Raynes, Peter
;
Shieh, Han-Ping D.
;
光電工程學系
The authors report a synchronized polymer-stabilization technique which can be used to stabilize the nonpermanent states in liquid crystal devices. In this paper, a relaxed-bend state in a pi cell which has a lifetime of only 80 ms is observed and then stabilized by this proposed technique. After stabilizing, the pi cell is immune to undesirable recovery into the splay or twist states, and its optical contrast is much higher than that of the conventional polymer-stabilized pi cell. (C) 2008 American Institute of Physics.
Investigation of the transient symmetric H state in a pi cell
(2007-08-13)
Yang, Bo-Ru
;
Elston, Steve J.
;
Raynes, Peter
;
Shieh, Han-Ping D.
;
光電工程學系
The so-called symmetric H (H-s) state has been reported to have submillisecond response times, which results from the symmetric profile of the liquid crystal director; however, no direct evidence has been obtained to show the profile symmetry. The difficulty in proving this symmetric structure by direct observation results from the short lifetime of H-s state (typically around a few tens of milliseconds). In the work reported here, the authors utilize a burst driving method along with stroboscopic illumination from blue and red light emitting diodes to capture conoscopic images for the H-s director profile; these showed good agreement with their modeling. (c) 2007 American Institute of Physics.
Stabilization of high-brightness relaxed bend state and investigation of fast-switching symmetric H state in a pi-cell by synchronized illumination technique
(2008-01-01)
Yang, Bo-Ru
;
Elston, Steve J.
;
Raynes, Peter
;
Shieh, Han-Ping D.
;
光電工程學系
The non-permanent states in a pi-cell have interesting electro-optical performances: the symmetric H (Hs) state has sub-millisecond response times and the non-biased bend (we term it as "relaxed bend," RB) state before collapsing into the twist state has high brightness. However, the short lifetime of these states makes them difficult to be studied and utilized. We propose a synchronized illumination technique to investigate the Hs state and stabilize the RB state. After stabilizing, the brightness of the ON-state is increased by a factor of 1.18 compared with the normal pi-cell; moreover, the intensity dynamic range of the RB state stabilized pi-cell is larger than that of the conventionally polymer-stabilized pi-cell.