Magneto and electro-optical measurements of Freedericksz threshold in PDNLC films

Abstract

Polymer dispersed liquid crystal (PDLC) films are promising material for the display application especially for the flexible panels. The base effect revealing in PDLC films is a light scattering controlled by the external field (electrical, magnetic, etc.) that transforms the orientational structure inside LC droplets. Recently we have proposed the numerical method to simulate the director configuration within bipolar nematic droplets with the rigidly fixed poles. This method allows determining the threshold characteristics of the PDLC films. To test the validity of the model we have earlier compared it with the data of the electro-optical measurements. However this analysis has been complicated by requirement to take account ofthe complex distribution ofelectric field inside the composite structure. Here we propose the magneto-optical method to verify the model. In this case the magnetic-field strength is homogeneous in PDLC films and it removes the above-mentioned problem. The measured values of threshold field agree well with the calculated ones. Moreover we compare the data obtained by magnetooptical method with the electrooptical measurements.