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1. Lasers: • What they are & how they work; • Laser tweezers: moving things with light without touching; • Laser applications: science, technology, & everyday life; 2. Invisibility: • Is this possible? Yes!!! • How it works & when we can buy our invisibility clothes? 3. Energy from light: • Solar cells & solar cell paints; 4. Holography & Diffraction Gratings Movie on Optical Science & Technology Rays: Waves: Laser Laser Flashlight Light bulb Flashlight Light bulb Principal components & how lasers work 1. Gain medium 2. Laser pumping energy 3. Mirror (100% reflection) 4. Output coupler mirror (98-99% reflection); 5. Laser beam • The term “LASER" is an acronym for Light Amplification by Stimulated Emission of Radiation. • Laser light is spatially coherent: either emitted in a narrow, low-divergence beam, or can be converted into one with the help of lenses. • Lasers are emitting light with a narrow monochromatic wavelength spectrum. Laser in a research lab: Compare different light sources: Intensity-distribution curve of light from a incandescent lamp Intensity-distribution curve of light from a White fluorescent tube Laser Some of numerous applications • • • • • • In CD, Blue-Ray, DVD, andHD-DVD players, Bar code readers; Laser pointers & laser tweezers; welding metal and other materials; "marking"—producing visible patterns such as letters; Military applications: range-finding, target designation, and illumination, weapons; • Medicine: laser surgery (i,.e., correction of cornea in the eye), diagnostics, and therapeutic applications; • Holography; • Laser microscopy; Moving Matter with Light without touching ??? Johannes Kepler To explain why tails of comets always point away from the Sun, Kepler suggested that the Sun was exerting a sort of radiant pressure. This led him in 1609 to propose sailing from the Earth to the Moon on light itself. This was and still is the stuff of science fiction. Moving and shaping matter with light 400 years later Kepler's ideas about moving matter with light are a reality (manipulated with invisible infrared light) Moving and shaping matter with light 400 years later Kepler's ideas about moving matter with light are a reality (manipulated with invisible infrared light) 9 A highly simplified view on In the lateral plane: How “Optical Trapping” Works Laser beam Along beam axis: Refraction changes light (photons) propagation direction; In return, the particle experiences an opposite force; Need refractive index of object > than that of medium; Optical forces for micron-sized objects: Power F~ pN for mW of laser powe r Fgravity ~ 10 3 pN c 10 Multiple traps: beam steering and shaping using spatial light modulators Equivalent ways of steering Phase-only SLM Focal plane Focal Plane Objective Objective Prism Objective lens Image (1) Galvano mirrors can be scanned at (1 10) kHz (2) Acousto-Optic Deflectors can be scanned at (0.1 10) MHz 11 Dynamically-reconfigurable focused laser beams Intensity Objective Beam steering Infrared CW Nd: YAG λ=1064nm co-localized with a HeNe Laser, λ=632.8nm 12 Manipulation of multiple micron-sized objects 13 Manipulation by CW Nd: YAG (λ=1064nm), visualized by HeNe laser (λ=632.8nm) Manipulating micron-sized bacteria 6x6 array Bacteria Pseudomonas aeruginosa: 9x9 array Laser power ~ 10mW per trap Burns, cancer patients, cystic fibrosis patients Planktonic cells send quorum sensing molecules/signals to determine if there are enough bacteria to start a biofilm Resistant to antibiotics 14 Particle manipulation with multiple traps 15 Shaping matter by infrared laser beams 17 Thank you !!! Optically-manipulated micro-string ( using an infrared laser beam);