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  • Volume 45, Issue 5

    • Volume 45, Issue 5

    Th Slm 01
    Software

    SLM and software automatically focus multiple cell nuclei

    May 1, 2009
    Viewing a cell under a microscope can be made much easier if the cell is held in place by an optical trap (“optical tweezers”).
    Th Super 01
    Optics

    Superhydrophobic surface improves solar cells in two ways

    May 1, 2009
    The absorption efficiency of solar cells can be improved through surface patterning (see www.laserfocusworld.com/articles/346272) and antireflective coatings (see www.laserfocusworld...
    Detectors & Imaging

    ‘Photonic Fence’ zaps mosquitoes with a laser

    May 1, 2009
    Thanks to research funding from Bill Gates and the United Nations, the laser is being eyed as a possible weapon in the war against malaria.
    Optics

    ‘Tweeter’ and ‘woofer’ deformable mirrors to work together on GPI

    May 1, 2009
    The Gemini Planet Imager (GPI) is an adaptive-optics instrument now under construction that will be installed at Gemini South, an 8 m telescope located atop Cerro Pachon in the...
    Research

    Integrated EOM looks good for intrachip optical interconnects

    May 1, 2009
    With their high speed and low power requirements, optical interconnects will someday provide the ultimate form of communication between components on a silicon microprocessor ...

    More content from Volume 45, Issue 5

    (Courtesy of RPI)
    A three-layer broadband GRIN antireflection coating for solar cells has a 49 nm dense TiO2 inner layer, a 99 nm layer of slightly porous SiO2, and a 360 nm layer of very porous SiO2.
    Optics

    OPTICAL COATINGS: Genetic algorithm designs omnidirectional solar-cell coating

    John Wallace
    May 1, 2009
    Typical silicon (Si) solar cells appear bluish for a reason. Because of the high refractive index of Si, the material’s bare untreated surface reflects 30% or more of the light...
    (Courtesy of Harvey Mudd College and Los Alamos National Laboratory)
    An optical refrigerator depends on removal of high-energy photons to cool a special laser-pumped material. In the simplest implementation, this is accomplished by directly attaching a thermal link that is then butt-coupled to a heat load (top). To improve refrigeration efficiency, several versions of optical-waveguide tapers and lens elements can be used as thermal links to remove absorptive photons (bottom).
    Optics

    SOLID-STATE CHILLERS: Waveguides, lenses keep optical refrigerator very cold

    Gail Overton
    May 1, 2009
    Back in 1995, Laser Focus World reported on a developing optical refrigeration technique from Los Alamos National Laboratory (Los Alamos, NM) in which 1020 nm light from an ytterbium...
    (Courtesy Institute of Physics, Chinese Academy of Sciences)
    A normalized second-order intensity fluctuation correlation function (Δg(2)) can be mathematically translated into a ghost image of pinholes in a copper foil, as shown in the actual cross section here (top). A simulation of a differently sized double-slit ghost image shows that away from the lensless imaging conditions the image becomes blurred (bottom).
    Detectors & Imaging

    IMAGING: Lensless ghost imaging uses true thermal light

    Gail Overton
    May 1, 2009
    Ghost imaging is as spooky as it sounds, and is indeed related to “spooky action at a distance” and quantum-entangled photons.
    Optics

    OPTICAL COMPONENTS: SOI/MEMS blazed grating extends efficiency and tunability

    Gail Overton
    May 1, 2009
    Wavelength-tunable microelectromechanical systems (MEMS)-based gratings with blazed surfaces are not new; however, the high diffraction efficiency needed for telecommunications...
    (Courtesy of Andreas Blug)
    A full image-based feedback system continuously monitors the keyhole welding process to make sure the weld is adequate.
    Detectors & Imaging

    METROLOGY: Laser welding gets a vision boost

    D. Jason Palmer
    May 1, 2009
    Keyhole welding, one of the most common means of laser welding in industry, has gotten a quality-control boost in the form of a new image-processing method developed by researchers...
    FIGURE 1. In the NIST-F1 cesium-fountain atomic clock six infrared lasers collect cesium atoms into a group and cool them to millikelvin temperatures. Then two vertical lasers “toss” the cesium atoms upward about a meter, passing through a cavity where they are irradiated by microwaves. When the lasers are switched off, the atoms fall back through the microwave cavity and through a laser beam that probes the atoms to see if the microwaves changed their energy level.
    Research

    PHOTONIC FRONTIERS: OPTICAL CLOCKS: Optical clocks set the pace in accurate timekeeping

    Jeff Hecht
    May 1, 2009
    The best optical clocks can already beat the best cesium atomic clocks for cutting-edge laboratory measurements; the next challenge is to develop more practical versions for application...
    (Courtesy of Ocean Thin Films)
    A microphotograph shows images of dichroic filters manufactured in a hybrid thin-film lithographic technique for a new, lower-cost megapixel multispectral imager. The filters can be custom designed to provide color images for low-light-level scenes (left) or for additional infrared filtering (right). Rectangular elements are 19 × 33 µm in size.
    Detectors & Imaging

    MULTISPECTRAL IMAGING: Filter-based multispectral imager has low complexity and cost

    Gail Overton
    May 1, 2009
    By using patterned dichroic filters fabricated with combined thin-film and lithography techniques and a CCD or CMOS sensor architecture, Ocean Optics (Dunedin, FL) and Ocean Thin...
    FIGURE 1. In this quasi-optical terahertz system, an indium tin oxide (ITO) plate is used to couple in the femtosecond-laser beam for detection of terahertz radiation.
    Optics

    TERAHERTZ IMAGING: Standard software optimizes terahertz imaging

    May 1, 2009
    Contrary to popular belief, off-the-shelf software can indeed tackle the unusual requirements of terahertz imaging—and in the process of optimizing such systems, help push terahertz...
    Images courtesy of Schott AG, High Q Laser Innovation GmbH, iie GmbH, Amtron GmbH
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    Research

    PREVIEW: LASER, WORLD OF PHOTONICS: Munich event may shun economic woes

    Stephen G. Anderson
    May 1, 2009
    Current travel restrictions at many firms may have kept some of us at our desks instead of out on the road, but they certainly haven’t dampened the enthusiasm of organizers of...
    FIGURE 1. A basic integrator lens array is shown at perpendicular (left), maximum angle of incidence (center), and illumination outside the acceptance (or integration) angle (right). A source with an arbitrary irradiance distribution (gray shape, bottom left) is transferred into a uniform irradiance distribution on the receiver by a symmetrical microlens array (bottom).
    Optics

    ILLUMINATION OPTICS: Köhler integration optics improve illumination homogeneity

    May 1, 2009
    Formed by a combination of reflective and/or refractive surfaces and organized in corresponding pairs, a Köhler integrator can be superimposed onto designed optical surfaces to...
    Th Cars 01
    Optics

    RAMAN SPECTROSCOPY: CARS microscopy peers deep into microstructures

    May 1, 2009
    Compared to scanning-electron microscopy, CARS microscopy produces a richer data set and is more conducive to in situ testing of microstructures created using two-photon polymerization...
    Research

    PHOTONICS INDUSTRY NEWS: Simple design of low-cost, organic white-light LED holds promise for widespread application

    May 1, 2009
    Researchers in China say they have developed a new type of light-emitting diode (LED) made from inexpensive, plastic-like organic materials.
    (Courtesy of the University of Augsburg)
    FIGURE 1. Blue, green, and red OLEDs are used as light sources in an experimental SPR sensor. The active area of the OLEDs is 10 mm long and 0.5 mm wide, so that the OLEDs can be regarded as linear light sources.
    Optics

    ORGANIC EMITTERS: OLEDs enable integrated surface-plasmon-resonance sensor

    May 1, 2009
    Organic light-emitting diodes offer much more than displays and lighting: they are perfectly suited as integrated light sources for many sensing applications.
    FIGURE 1. Existing applications for lasers within the solar industry include c-Si edge isolation (left) and thin-film patterning (right).
    Lasers & Sources

    PHOTONICS APPLIED: PHOTOVOLTAICS: A sunny outlook for lasers in solar

    Finlay Colville
    May 1, 2009
    Changes in solar supply-demand dynamics, coupled with new tooling requirements for next-generation photovoltaics, are likely to increase adoption rates of lasers used in production...
    FIGURE 1. In a microphotoluminescence spectroscopy setup laser light is directed through a microscope objective and focused onto the sample (left). The sample rests in a cryogenic environment and is mounted to a cryogenic compatible stage. The photoluminescence (PL) is collected by the objective and separated from the laser light by a dichroic beamsplitter (BS). The PL is then spectrally filtered by a bandpass filter (BP). The location on the sample surface is monitored by an imaging CCD camera and the excitation power is monitored at the photodiode (PD). A Hanbury-Brown and Twiss (HBT) interferometer with a time correlator is used to verify single-photon emission. Photons are separated at the 50:50 beamsplitter (BS) and detected by the single-photon detectors (SPDs). The time between successive arrival times, Δt, is tabulated by the time correlator (upper right). A histogram of detection events using the HBT setup with a quantum-dot SPS under pulsed excitation shows a dramatic lack of events at Δt = 0, which indicates the single-photon character of the emission (lower right).
    Research

    SINGLE-PHOTON SOURCES: Quantum dots may hold the key to secure quantum cryptography

    May 1, 2009
    Quantum-dot-based single-photon sources are fast and efficient and remain at the forefront of candidates for use in quantum information schemes.