P. Van De Witte et al., Modification of the twist angle in chiral nematic polymer films by photoisomerization of the chiral dopant, J APPL PHYS, 85(11), 1999, pp. 7517-7521
A method for the production of polarization sensitive recordings in liquid
crystalline polymers is presented. The system is based on local modificatio
n of the twist angle of chiral nematic polymer films. The twist angle of th
e polymer film is varied by modifying the chemical structure of the chiral
dopant. Here a photoisomerizable menthone derivative is used that has a fiv
efold difference in helical twisting power between the E and the Z isomer.
The twist angle of the film can be varied between -90 degrees and 0 degrees
by introducing a nonphotosensitive chiral dopant with opposite twisting se
nse. Complex pictures with gray scales can be recorded in the films with bl
ack and white contrasts higher than 20. (C) 1999 American Institute of Phys
ics. [S0021-8979(99)05011-2].