Topic:     

In-situ control of surface molecular order in nematic liquid crystals using a localized polymer network and its application to optical elements


Speaker:
                    

Vassili Sergan

Professor, Dept. of Physics & Astronomy,            

California State Univ.            

            

         Wednesday, April 26 - 6:00 P.M.

Microsoft Building 87 (Hardware Blgd.) Room 1004

4729  154th Place NE.

Redmond, WA 98052

                 
Call-In / Webinar
For remotely attending, we are now using GoToWebinar. To register, click on the following link:            

         https://attendee.gotowebinar.com/register/4442715652478915841

           

The Seminar is free. Non-Members are welcome. For additional information on upcoming and past chapter meetings visit: http://www.sidchapters.org/pacificnorthwest/index.htm

RSVP to Gary Johnson at Gary.Johnson@Tek.com or (503) 627-1985.

           

Visit to Microsoft RPC labs:

There will be a special walk-through of Microsoft Rapid Prototyping Center as well. 

Tour will be 4.30-5.30pm to cover the RPC and anechoic chambers.

This is a unique opportunity.  The public are not normally allowed in…

The labs are located at the same building as the talk (Bldg. 87)


                               

ABSTRACT

We developed a liquid crystal (LC) alignment technique that allows for local control of the polar pre-tilt angle in the range 0-90º. This was achieved via the formation of a polymer network localized in the vicinity of the LC cell substrates. The network was formed as a result of in-situ UV-light-induced polymerization of a photo-reactive monomer added in concentrations of 0.5-1%. Localization of the polymer network at the LC-substrate boundary was achieved by the application of a high voltage before polymerization. The resultant pre-tilt angle was determined by the voltage applied during the polymerization and/or the duration of the voltage application before the polymerization step. The desired pre-tilt angle can be set over a small area of the sample which allows for the fabrication of LC devices with spatially variable optical retardation. Using this method, we fabricated electrically tunable/switchable converging lens, bi-prism, and phase diffraction grating.


SPEAKER BIO
           

Vassili Sergan, Professor of Physics at California State University, Sacramento started his scientific career in 1984 after graduating Rovno State University (Ukraine) with master’s degree in Math and Physics. His research (at Institute of Physics, Ukrainian Academy of Sciences) in the area of electro-optics of Liquid Crystals (LC) earned him PhD in Solid State Physics in 1990. After that he occupied various visiting research positions around the world, while maintaining his principal appointment as a senior research fellow at Institute of Physics, Ukrainian Academy of Sciences. His main research focus was always related to electro-optics of Liquid Crystals: improvements of PDLC, studies of switching dynamics of cholesteric displays, using LC in laser beam steering devices, studies of alignment and anchoring of LC on various surfaces, implementation of polymer-doped LCs, just to name few.

In 2002, Vassili Sergan joined Physics and Astronomy Department at California State University, Sacramento. His main responsibility there is teaching, but he manages to maintain an active research program there. His publication portfolio contain more than 50 papers in highly regarded journals, several US and European patent. He presenter his work at numerous international conferences and Symposia. He serves currently as the Director of the SID Ukraine chapter.

               

PNW SID 17 Apr 26.pdf