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  • Volume 45, Issue 11

    • Volume 45, Issue 11

    Th Vga 1109 01
    Detectors & Imaging

    VGA OLED microdisplay is picoprojector source

    Nov. 1, 2009
    An all-digital VGA (640 x 480-pixel) resolution full-color organic-light-emitting-diode (OLED) microdisplay is being developed by engineers at Fraunhofer IPMS (Dresden, Germany...
    Optics

    Black silicon provides antireflection surface for efficient solar cells

    Nov. 1, 2009
    Black silicon—formed by the irradiation of silicon with an ultrafast laser in a sulfur-based atmosphere, or by various etching processes—is finding applications as varied as IR...
    Research

    Modelocked femtosecond laser emits at 2420 nm

    Nov. 1, 2009
    A room-temperature, long-wavelength (2 to 3 µm) femtosecond laser would be useful for high-harmonic generation in the deep-UV or soft-x-ray regions, or as a pump source to create...
    Research

    Photonic crystal is immune to backscattering

    Nov. 1, 2009
    Normally, if photons can travel in a certain direction through a medium, they can also travel in the reverse direction—a phenomenon called time-reversal symmetry.
    Th Light 1109 01
    Research

    Light controls cell movement

    Nov. 1, 2009
    In addition to using light to illuminate and study cellular processes, researchers at the University of California, San Francisco (UCSF) have developed a light-activated protein...

    More content from Volume 45, Issue 11

    FIGURE 1. A three-beam interferometric combiner is fabricated in lithium niobate. Inputs are from the left; phase-modulating electrodes are shown in color.
    Optics

    INTERFEROMETRY: Beam combiner can help find exoplanets

    John Wallace
    Nov. 1, 2009
    The search for exoplanets (planets orbiting other stars) has taken several forms; a well-known one is the transit method, in which the brightness of a star is monitored to spot...
    The original lithographic setup (left) produced 0.75 mm of longitudinal spherical aberration (LSA; seen as focal-point displacement as a function of aperture) at a recording wavelength of 632 nm. The improved setup, containing an asphere, is still simple in form but has a greatly reduced LSA.
    Optics

    OPTICAL FABRICATION: Simple setup makes HDOEs

    John Wallace
    Nov. 1, 2009
    Given the choice between developing a custom optical system or one that can make do with commercial “off-the-shelf” lenses, any designer would choose the latter.
    (Courtesy of Hella)
    FIGURE 1. A full-LED headlamp prototype for an Opel Signum auto uses different optical modules for different signal functions: six lenses for the dipped beam/low beam; three lenses at the bottom for the main beam/high beam; two small lenses for the cornering light; and daytime running lights from ten LEDs behind a flat light-guide element. The direction indicator consists of three LEDs with reflector systems on the top of the headlamp. Based on individual light-source data for different LED types, Hella uses its own calculation software for free-form lenses and reflectors to optimize each part of the light distribution—especially the homogeneous transition between different areas.
    Lasers & Sources

    PHOTONICS APPLIED: TRANSPORTATION: Auto industry is set to reap cost and performance benefits from photonics

    Gail Overton
    Nov. 1, 2009
    Whether it’s LED headlamps, night-vision safety systems, or emerging laser-ignition systems, the compact, low-energy-consumption performance-rich attributes of photonic technologies...
    Th Wave 1109 01
    Test & Measurement

    WAVEFRONT ANALYSIS: Digital wavefront sensors boost resolution, sensing options

    Nov. 1, 2009
    Analog optical-wavefront sensors are gradually being replaced by fully digital wavefront cameras, which can simultaneously visualize video images and measure wavefronts at a resolution...
    (Courtesy of LLNL)
    In the Confined Large Optical Scintillator Screen and Imaging System (CoLOSSIS), an x-ray beam penetrates the test object, which casts shadow on the glass scintillator. The scintillator converts the x-ray radiation to green light, which is reflected by mirrors (not shown) and imaged by four lenses onto four CCD cameras.
    Optics

    X-RAY OPTICS: Novel optics improve nuclear-weapon safety

    Gail Overton
    Nov. 1, 2009
    The U.S. Department of Energy’s National Nuclear Security Administration (NNSA) continues to pursue a smaller, safer, more secure, and less-expensive nuclear-weapons arsenal.
    (Courtesy of Edmund Optics)
    FIGURE 1. Three Standard high-numerical-aperture, near-UV component designs operate at 266 nm. The aspheric lens provides two orders of magnitude smaller spot size than the spherical singlet.
    Optics

    UV OPTICS: New optical developments boost near-UV applications

    Gregg Fales
    Nov. 1, 2009
    Limited choices for substrate/coating materials and processing costs keeps deep-ultraviolet (100–250 nm) applications relatively sparse, but the near-ultraviolet (250–400 nm) ...
    (Courtesy of the National Institute for Materials Science)
    A prototype far-UV emitter combines a cold-cathode electron emitter with an hBN FED array 17 × 1.6 mm in size (bluish-white line). Note the AA battery placed next to it as a size comparison. For this particular device, impure hBN powder was used for the fluorescent screen because it emits blue light that can be captured with a commercially available digital camera.
    Research

    FIELD-EMISSION LIGHT SOURCES: Handheld far-UV emitter runs on AA batteries

    John Wallace
    Nov. 1, 2009
    Flashlights are handy things. With the advent of LEDs based on gallium nitride, near-UV flashlights have recently become available; they are useful for some forensic work, as ...
    (Courtesy of Photon Kinetics)
    FIGURE 1. A near-field image of a pigtailed VCSEL source is shown with the encircled flux calculated from the image plotted with limits established for 1 Gbit VCSELs (< 25% at 4.5 µm and > 75% at 15 µm; right).
    Lasers & Sources

    FIBER-OPTIC TEST & MEASUREMENT: Gigabit Ethernet drives evolution of multimode fiber-optic specifications

    Nov. 1, 2009
    While single-mode fibers dominated the fiber-optic landscape in the 1990s, multimode fibers have charged back into the limelight, thanks in part to optical measurement standards...
    (Courtesy of Universidad de Murcia)
    A mathematical algorithm converts the image formed by the reflection from two eyes passing through an adaptive-optics apparatus that includes a liquid-crystal-on-silicon programmable phase modulator (PPM-LCOS) to a microlens-covered sensor (Hartmann-Shack or H-S real time video) into a wavefront-aberration (WA) plot for the right and left eye. The adaptive-optics vision simulator is used to study the impact of ocular aberrations on binocular vision.
    Optics

    ADAPTIVE OPTICS: Adaptive-optics simulator studies binocular vision

    Gail Overton
    Nov. 1, 2009
    Adaptive-optics (AO) technology is actively applied in the field of ophthalmology for diagnosis of retinal disease and analysis of ocular aberrations such as coma and spherical...
    (Courtesy of Lawrence Livermore)
    FIGURE 1. NIF’s Laser Bay 2, shown looking away from the target area, includes 96 of the 192 beam lines. Note the three workers in yellow hard hats for scale.
    Research

    PHOTONIC FRONTIERS: THE NATIONAL IGNITION FACILITY: NIF is up and running at last

    Jeff Hecht
    Nov. 1, 2009
    The National Ignition Facility has yet to reach its full 1.8 MJ UV pulse energy, but it has already begun target experiments. Managers plan a slow ramp-up to full power, and hope...
    (Courtesy of Max Planck Institute for Biophysical Chemistry)
    Imaging of a fluorescent-stained mammalian microtubular cell network shows better detail using the single-path STED microscope (b) than a conventional confocal microscope (a), especially evident in a close-up region (c) in which STED microscopy discerned individual fibers. The smallest distance between well-resolved features for the STED setup is 80 nm (d).
    Optics

    MICROSCOPY: Single-path design simplifies STED microscopy

    Gail Overton
    Nov. 1, 2009
    In 2008, researchers at the Max Planck Institute for Biophysical Chemistry (Göttingen, Germany) and the German Cancer Research Center (Heidelberg, Germany) developed an isotropic...
    Th Optics F 1109 01
    Optics

    OPTICS FABRICATION: Molded glass aspheres boost optical-design choices

    Nov. 1, 2009
    Precision glass molding of aspheric lenses allows a wide variety of optical designs with smaller size, reduced weight, and no post-polishing; these lenses can be made economically...
    Fiber Optics

    Fiber laser is both Q-switched and modelocked

    Nov. 1, 2009
    Modelocked lasers produce ultrashort pulses at high frequencies, but generally with low pulse energies (or with ultralong cavity lengths to increase pulse energy).
    (Courtesy of Toptica)
    FIGURE 1. An ultrachrome source, the iChrome (below), incorporates a fiber-laser oscillator and amplifier (OSC/AMP), supercontinuum in the IR (SCG), frequency doubling into the visible (SHG), and a single-mode/polarization-maintaining (SM/PM) delivery fiber.
    Lasers & Sources

    TUNABLE LASER SOURCES: Fully tunable visible laser source is valuable for biophotonics

    Nov. 1, 2009
    A new laser that is quickly and accurately tunable across 160 nm has advantages over existing visible “ultrachrome” sources used in medical and biological applications.
    Courtesy of PerkinElmer
    FIGURE 1. Examples of SiPM chips are sensors with sizes of 1.4 × 1.4, 3 × 3, and 5 × 5 mm.
    Detectors & Imaging

    PHOTOMULTIPLIERS: Solid-state photon detector has low crosstalk

    Nov. 1, 2009
    A silicon photomultiplier with two forms of crosstalk suppression is a nearly ideal photon detector for industry, nuclear medicine, and research.