Guest-host liquid crystal polarizer for electrically switchable polarization in CCTV systems

This study proposes a liquid crystal-based polarizer system using guest-host liquid crystals (GHLC) doped with dichroic dye, which enables switching between polarization and normal CCTV modes. The GHLC polarizer overcomes the limitation of reduced light transmittance in low-light conditions, a common drawback of conventional polarizing filters. The system leverages the dielectric anisotropy of liquid crystals and the absorption anisotropy of the dye and enables electrical modulation of transmittance by adjusting the polarization orientation. This functionality facilitates switching between polarization and normal modes, contingent on the amount of light reflected from the subject, thereby ensuring real-time adaptability across diverse lighting environments. Furthermore, the system sustains optimal CCTV performance without necessitating physical intervention, offering enhanced flexibility and efficiency compared with conventional polarizing filter systems.