Alternate Applications of Liquid CrystalsOverviewLC Switchable GratingsLC GratingsHPDLC Switchable Bragg GratingSpatial Light ModulatorsSLMLiquid Crystal DisplayLCD“Smart” WindowsSlide 11Solar CellsLC ThermometersLC ThermometerQuestions?Alternate Applications of Alternate Applications of Liquid CrystalsLiquid CrystalsBobby GeevarugheseBobby GeevarugheseECE-E443ECE-E443OverviewOverviewElectrically Switchable Bragg GratingsElectrically Switchable Bragg GratingsSpatial Light ModulatorsSpatial Light ModulatorsLCDLCD““Smart” windowsSmart” windowsSolar PowerSolar PowerLC ThermometersLC ThermometersLC Switchable GratingsLC Switchable GratingsUseful in performing beam steering, beam Useful in performing beam steering, beam shaping, and other modifications of light intensity shaping, and other modifications of light intensity or phaseor phasePreferable in WDMPreferable in WDMBragg phenomenonBragg phenomenonConstructive/destructive interferenceConstructive/destructive interferenceLC GratingsLC GratingsDigilens' 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. http://optics.org/articles/ole/6/9/7/1/oleholo2%5F87%2D01HPDLC Switchable Bragg GratingHPDLC Switchable Bragg GratingSpatial Light ModulatorsSpatial Light ModulatorsPrimary use in converting incoherent Primary use in converting incoherent images to coherentimages to coherentPotential in correcting defocus, Potential in correcting defocus, astigmatism, and higher order aberrations astigmatism, and higher order aberrations of human eyesof human eyesLiquid crystal advantagesLiquid crystal advantagesLow cost, reliability, compactness, low power Low cost, reliability, compactness, low power consumption, consumption,SLMSLMhttp://www.see.ed.ac.uk/research/IMNS/projects/slm/slm.htmlLiquid Crystal DisplayLiquid Crystal DisplayNematic phase liquid crystals.Nematic phase liquid crystals.Nematics consist of a definite order or patternNematics consist of a definite order or patternConsists of two sheets of polarizing Consists of two sheets of polarizing material with a liquid crystal solution material with a liquid crystal solution between thembetween themElectric current is passed through the Electric current is passed through the liquid crystals (pixels) allowing varying liquid crystals (pixels) allowing varying degrees of light to pass or not degrees of light to pass or notLCDLCDSegment of seven Segment of seven segment displayed segment displayed is electrifiedis electrifiedLiquid crystal twists Liquid crystal twists polarized light from polarized light from front filter front filter Allows light to Allows light to bounce off rear bounce off rear reflector and reflector and illuminate segmentilluminate segmenthttp://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0016763.html““Smart” WindowsSmart” WindowsNecessary due to the Necessary due to the depletion of available depletion of available energyenergyAble to block all light or Able to block all light or just somejust someWith an electrical charge, With an electrical charge, crystals will align parallel crystals will align parallel to each other and let light to each other and let light through or otherwise be through or otherwise be scatteredscatteredWith liquid crystals there With liquid crystals there is no intermediate settingis no intermediate settinghttp://home.howstuffworks.com/smart-window3.htm““Smart” WindowsSmart” Windowshttp://home.howstuffworks.com/smart-window3.htmSolar CellsSolar CellsExpensiveExpensive20-30 cents compared to 6-7 cents20-30 cents compared to 6-7 centsOrganic “self assembling” thin filmsOrganic “self assembling” thin filmsContains perylene and HBC-PhC12 which Contains perylene and HBC-PhC12 which forms liquid crystals that when combined forms liquid crystals that when combined leaves perylene crystals above HBC filmleaves perylene crystals above HBC filmMolecule absorbs light, produces an electron, Molecule absorbs light, produces an electron, and leaves behind a holeand leaves behind a holeHBC has disk shaped molecules that stack to HBC has disk shaped molecules that stack to create molecular wires for hole transportcreate molecular wires for hole transportLC ThermometersLC ThermometersPortrays temperatures as colors and can Portrays temperatures as colors and can be used to monitor changes caused by be used to monitor changes caused by heat flowheat flowVarious uses from child care to weldingVarious uses from child care to weldingContains rod shaped cholesteric liquid Contains rod shaped cholesteric liquid crystals that form a spiral staircasecrystals that form a spiral staircaseReflects specific color of light with same Reflects specific color of light with same distance (wavelength) as a full rotationdistance (wavelength) as a full rotationLC ThermometerLC Thermometer