High-ambient-contrast augmented reality with a tunable transmittance liquid crystal film and a functional reflective polarizer
We have proposed a compact, yet high ambient contrast ratio augmented reality (AR) system by incorporating a tunable transmittance liquid crystal (LC) cell and a thin functional reflective polarizer. The broadband polarization-independent guest–host LC cell can change the transmittance from ~73% to ~26% with merely 8 V. Its response time (~50 ms) is at least 10× faster than that of photochromic materials used in commercial transition glasses. Combining the LC cell with a light sensor, the tunable transmittance LC cell can efficiently improve the ambient contrast ratio of the AR system under different lighting conditions. Meanwhile, the functional reflective polarizer works similarly to a polarizing beam splitter, except that it is much more compact and lighter weight. With some modification, we also designed a functional reflective polarizer to help people with color vision deficiency.
The History of the International Liquid Crystal Society from 1990-2015.
“The International Liquid Crystal Society has now been in existence for 25 years. It has established itself as an organisation that promotes and supports liquid crystal science around the world. This article chronicles the foundation of the Society, and gives a brief account of the history of international conferences on liquid crystals.”
Photoinduced order-increasing phase transitions can occur in dye-liquid crystal mixtures when the photoproduct of the excitation of the dye molecules is more compatible with the liquid crystalline medium than the initial dye species. A detailed investigation of the photoinduced changes of the phase behavior and optical properties of mixtures of liquid crystals with naphthopyran guests upon exposure to light at 365 nm is presented here. In these guest-host systems, the nematic-to-isotropic phase transition temperature is increased upon irradiation. We show that the nematic range can be extended up to 2.9 °C by illumination in 5CB (4−n-pentyl-4′-cyanobiphenyl) liquid crystal mixtures. The order parameter is significantly increased by illumination at all temperatures within the nematic range and the changes are larger at higher concentrations of the guests. In particular, the illuminated guest-host mixtures exhibit order parameters close to those of the neat liquid crystal host at the same temperature relative to the clearing point. An improved understanding of the photophysical processes taking place at the molecular level in these material systems can inform the design of photoresponsive materials and enhance their potential utility in optical or photonic devices.
Ballistic transitional eyewear protected Lt. Anthony Aguilar when a bomb exploded near his vehicle. Read the article here.