Fabrication andCharacterization ofaRepositionable Liquid MicroLens System

Anovel method toimprove boththelateral positioning andfocal length tuning accuracy ofaliquid lens inamicro lens system, based ontheelectrowetting ondielectrics (EWOD)principle, isdescribed. Thissystem consists ofadevice, encapsulated with apackaging technique, fabricated onatransparent substrate featured withanarray ofelectrodes andastructured surface whose periodicity issmaller than theelectrode's dimension. Withvariable applied voltage signals, theliquid lens isactuated precisely inthelateral position andalso tuned dynamically irrespective ofthelens position onthesubstrate. Theaccuracy oflateral positioning ismainly dependent onthestructure ofthedielectric surface. Measurements ofthefocal length tuning range and thepositioning accuracy arepresented. A first design ofreconfigurable micro lens system, whichhasdiverse application as adaptive wave-front sensing, optical tweezers andetc, isdemonstrated.