1. Alternate Applications of Liquid Crystals
Bobby Geevarughese
ECE-E443

2. Overview Electrically Switchable Bragg Gratings
Spatial Light Modulators
LCD
“Smart” windows
Solar Power
LC Thermometers

3. LC Switchable Gratings
Useful in performing beam steering, beam shaping, and other modifications of light intensity or phase
Preferable in WDM
Bragg phenomenon
Constructive/destructive interference

4. LC Gratings http://optics.org/articles/ole/6/9/7/1/oleholo2%5F87%2D01
Digilens' gratings are created by using lasers to polymerize a mixture of monomer and liquid crystals. An applied AC voltage makes the material transparent, enabling light to pass through it.

5. HPDLC Switchable Bragg Grating

6. Spatial Light Modulators
Primary use in converting incoherent images to coherent
Potential in correcting defocus, astigmatism, and higher order aberrations of human eyes
Liquid crystal advantages
Low cost, reliability, compactness, low power consumption,

7. SLM

8. Liquid Crystal Display
Nematic phase liquid crystals.
Nematics consist of a definite order or pattern
Consists of two sheets of polarizing material with a liquid crystal solution between them
Electric current is passed through the liquid crystals (pixels) allowing varying degrees of light to pass or not

9. LCD Segment of seven segment displayed is electrified
Liquid crystal twists polarized light from front filter
Allows light to bounce off rear reflector and illuminate segment

10. “Smart” Windows Necessary due to the depletion of available energy
Able to block all light or just some
With an electrical charge, crystals will align parallel to each other and let light through or otherwise be scattered
With liquid crystals there is no intermediate setting

11. “Smart” Windows

12. Solar Cells Expensive Organic “self assembling” thin films
20-30 cents compared to 6-7 cents
Organic “self assembling” thin films
Contains perylene and HBC-PhC12 which forms liquid crystals that when combined leaves perylene crystals above HBC film
Molecule absorbs light, produces an electron, and leaves behind a hole
HBC has disk shaped molecules that stack to create molecular wires for hole transport

13. LC Thermometers
Portrays temperatures as colors and can be used to monitor changes caused by heat flow
Various uses from child care to welding
Contains rod shaped cholesteric liquid crystals that form a spiral staircase
Reflects specific color of light with same distance (wavelength) as a full rotation

14. LC Thermometer
                                                                  
                                                                   

15. Questions?