Local dynamics in polymer-dispersed liquid crystals studied by near-field scanning optical microscopy

Electric-field-induced molecular reorientation dynamics are studied in localized regions within polymer-dispersed liquid-crystal (PDLC) films, using time-resolved near-field scanning optical microscopy (NSOM) methods. A concentrated electric field is applied across the PDLC film, between the metallized NSOM probe and the conductive, transparent substrate supporting the sample. The electric field is modulated as a square wave form at (sub)-kilohertz frequencies. Subsequent liquid-crystal (LC) reorientation is observed by crossed-polarized, transmitted-light NSOM methods. The results show dramatic spatial variations in the time scale over which the molecules reorient. The variations are interpreted based on proximity of the region probed to the polymer-LC interface. (C) 1998 American Institute of Physics. [S0003-6951(98)01250-9].