Electro-optical window

Figure 40.1 Electro-optical window based on liquid crystal dispersions in sol-gel matrices, in off-state (a) and on-state (b).

University in cooperation with industry, have shown promise for commercial application. These films can be sandwiched between conducting plastic films to form continuous sheets. They are highly scattering in the OFF state and window-glass clear in the ON state. They do not use surface alignment layers, polarizers or cell seals. They are durable and aesthetically pleasing. A new class of electro-optic materials, they are superior in many ways to conventional liquid crystal shutters and offer exciting new applications. 

PDLC and NCAP films are just now reaching commercialization. Some applications, such as large area signs and switchable windows, could not be served by previous electro-optic materials. Recent innovations in PDLC films are expanding the possible applications for PDLC materials and improving their overall performance. 

Some ceramics are transparent to light of specific frequencies. These optical ceramics are used as windows for infrared and ultraviolet sensors and in radar installations. However, optical ceramics are not as widely used as glass materials in applications in which visible light must be transmitted. An electro-optic ceramic such as lead lanthanum zirconate titanate is a material whose ability to transmit light is altered by an applied voltage. These electro-optic materials are used in color filters and protective goggles, as well as in memory-storage devices. 

The preparation and characterization of vanadium oxide (V2O5) modified tungsten oxide (WO3) films by pulse laser deposition were recently examined [61]. Tungsten oxide coatings are used in many electro-optical applications including catalysts, solar cell windows, electrochromic and gasochromic devices, optical memory and... 

ITU-T-approved hand assignment in the low attenuation window of the silica fibers the wavelength range involves 1260-1360 nm = 0-band 1360-1460 nm = E-band 1460-1530 nm = S-band 1530-1565 nm = C-band 1565-1625 nm = L-band and 1625-1675 nm = U-band (used in monitoring). (Courtesy EXPO Electro-Optical Engineering Inc. Printed with permission.) (From Raja, M.Y.A. and Ilyas, M., Optical transport networks A physical layer perspective, in The Handbook of Optical Communication Networks, Ilyas, M., Ed., CRC Press, Boca Raton, FL, 2003, p. 391.)... 

The most restrictive drawback is that the deposition should be carried out on a conducting or a doped semiconducting surface. This is why it is not yet popular for most high-tech electro-optic applications, whereas it is extremely useful for coatings in the automotive industry, for the fabrication of batteries, fuel cells, and electrochromic windows, all of which involve films on conductive supports. Electrophoretic deposition conditions involve the presence of colloidal suspensions, but methods for in situ formation of particulates by faradaic acidification or base formation were amply described as well [44]. Finally, gas evolution (Hj) may be considered a technicality, but it adversely affects the film quality and may pose a safety hazard unless appropriately handled. 

Moreover, polymer dispersed liquid crystals (PDLC) have been extensively studied as promising candidates new materials for application in the field of thermo- and electro-optical devices, such as optic shutters, smart windows, optical sensors, memories and flexible display devices. 

Besides these two standard cell alignments, there are many other variations such as hybrid, twisted, supertwisted, fingerprint, multidomain vertically aligned, etc. Industrial processing of these nematic cells, as well as the transparent conductive coating of the cell windows for electro-optical device applications, is understandably more elaborate. 

There is increasing interest in optical devices commonly called electro-chromic (smart) windows (EWs), i.e. ECDs which allow electrochemically... 

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