CHOLESTERIC LIQUID-CRYSTAL SMART REFLECTORS

We present results concerning the development of liquid crystal smart reflectors, consisting of a cholesteric liquid crystal with temperatur e sensitive helix pitch, in combination with a light absorbing dye. Li ght entering the liquid crystal is absorbed by the dye, generating hea t which raises the temperature of the liquid crystal. The resulting ch ange in the helix pitch of the cholesteric causes an increase in its r eflectivity, reducing the intensity of light that can be absorbed by t he dye. This negative feedback stabilizes the reflector for a given li ght intensity. The smart reflector thus achieves a reflectivity which increases with increasing intensity of incident light. We report on tw o configurations of the device, with both experimental measurements an d mathematical models of the system.