• Subscribe
  • Podcasts
  • Videos
  • Webinars
  • White Papers
  • Buyer's Guide
  • Get Published!
  • 2024 Innovators Awards
  • Back Issues >
  • Laser Focus World >
  • Volume 45, Issue 2

    • Volume 45, Issue 2

    Th Manu 01
    Optics

    Manufacturers’ Product Showcase

    Feb. 1, 2009
    Nanopositioning piezo-based stages and actuators deliver nanometer resolution, fast response and are robust.
    FIGURE 1. The emission spectrum of a strain-adjusted LED, shown here in arbitrary units (a.u.), changes shape with increasing injection current, causing the color to change from yellow to white to blue.
    Lasers & Sources

    WHITE-LIGHT LEDS: Pitted LEDs emit broad spectra

    John Wallace
    Feb. 1, 2009
    Two types of phosphor-free white-emitting LEDs have been developed that appear, at first glance, to rely on the same concept for white-light emission; however, when examined in...
    Th New P 01
    Optics

    New Products

    Feb. 1, 2009
    Off-axis beam collimators have a surface accuracy better than λ/10 p-v, producing no central obscuration and obtaining efficient transmission.

    More content from Volume 45, Issue 2

    Th Diff 01
    Optics

    DIFFRACTIVE OPTICS: Harmonic optical element simplifies Blu-ray optics

    Feb. 1, 2009
    A harmonic optical element added behind the objective lens of a Blu-ray pickup allows it to handle Blu-ray, DVD, and CD wavelengths with a single optical system.
    FIGURE 1. In the microscope with a Shack-Hartmann wavefront sensor, the 45° beamsplitter1 (Semrock, Rochester, NY) allows the laser light to be focused onto the sample, while the 90/10 beamsplitter BS2 allows the science camera and the wavefront sensor to see the fluorescent microsphere simultaneously. Lenses L1 and L2 are 65-mm-focal-length lenses that image the aperture of the objective onto the Shack-Hartmann sensor; P1 and P2 are conjugate planes. The field-stop between L1 and L2 blocks the light coming from other parts of the field of view, allowing only the light from the bead to pass. Note, the field-stop could be moved farther down the system because it is needed only by the wavefront sensor. The large distance between L1 and the aperture (P1) allows for the excitation laser (HeNe, λ = 632 nm) to be placed in this area. A source filter was added after L2 to reduce the effect of scattered light by the embryo and allow the wavefront sensor to see only the emission light. L3 demagnifies the pupil by a factor of two so that it can fit into the cooled camera (Roper Scientific, Acton, NJ).
    Research

    ADAPTIVE OPTICS: Fluorescent microspheres enable adaptive-optics microscopy

    Barbara Gefvert
    Feb. 1, 2009
    Adaptive optics has tantalized researchers looking for ways to image through thick biological tissue–but the approach is not straightforward.
    (Courtesy of Hewlett-Packard Laboratories)
    Time-resolved photoluminescence measurements are compared for two structures: an LED epitaxial stack without a silver layer (red line) and an LED epitaxial stack with a 40 nm gap between the quantum well of the stack and a silver layer (dashed black line). Decay time is significantly decreased due to the presence of surface plasmon polaritons for the device with a silver layer. The gap between the silver layer and the quantum well structure also has a major impact on decay time (inset).
    Lasers & Sources

    OPTICAL COMMUNICATIONS: Plasmonic LED approaches 10 GHz modulation speed

    Gail Overton
    Feb. 1, 2009
    Commercial light-emitting diodes (LEDs) are only capable of 1 GHz maximum modulation speeds because of slow carrier recombination, limiting them to applications in short-haul ...
    Th Femto 01
    Research

    Femtosecond pulses create microlenses in glass

    Feb. 1, 2009
    Direct femtosecond laser writing is emerging as an alternative technique to lithography for fabrication of microstructures inside transparent materials.
    (Courtesy Swiss Federal Institute of Technology)
    FIGURE 1. The Jungfraujoch observatory in the Swiss Alps houses instrumentation that uses vibrational Raman spectroscopy to measure water vapor in the troposphere, as well as rotational Raman spectroscopy to perform temperature measurements on air molecules at altitudes up to 20 km. Differential-absorption LIDAR (DIAL) is also used to measure ozone in the troposphere.
    Test & Measurement

    PHOTONICS APPLIED: ATMOSPHERIC MONITORING: New photonic devices boost environmental monitoring capabilities

    Gail Overton
    Feb. 1, 2009
    In our increasingly “green” world, the need for portable and accurate atmospheric monitoring equipment, in which photonics plays a significant role, has expanded as society weighs...
    Th Mems 01
    Optics

    MEMS obscura telescope tracks fast objects

    Feb. 1, 2009
    A novel pinhole-type camera that substitutes a microelectromechanical systems (MEMS)-based micromirror array for the pinhole has been developed by the Research Center of MEMS ...
    (LLNL photo)
    FIGURE 1. The Solid State Heat Capacity Laser at the Lawrence Livermore National Laboratory used ceramic slab amplifiers to generate an average power of 67 kW.
    Lasers & Sources

    PHOTONIC FRONTIERS: MATERIALS FOR SOLID-STATE LASERS: New materials expand capabilities of solid-state lasers

    Jeff Hecht
    Feb. 1, 2009
    Ceramic hosts, transition-metal doping of II-VI hosts, and optically pumped semiconductor lasers are expanding the range of solid-state laser capabilities to new wavelengths and...
    FIGURE 1. Drivers provide the operating current entering a system. The 500B series laser-diode driver from Newport (left) is a low-noise current source with long-term stability of better than 50 ppm/°C with four models covering laser currents from below 50 mA up to 6 A. A USB 2.0 connector interface is unique for interfacing with a remote computer. The LDX36000 family of high-power laser-diode current sources from ILX Lightwave (right) provides continuous-wave and pulsed operation with currents up to 220 A and voltages to 70 V for driving stacks and arrays of lasers.
    Positioning, Support & Accessories

    PRODUCT FOCUS: POWER SUPPLIES: Laser-diode power-supply basics: performance depends on specification

    Valerie Coffey-Rosich
    Feb. 1, 2009
    Bench-top laser-diode drivers and controllers have a wide variety of features, from voltage and temperature control to safety features and surge protection. Know the most important...
    Th Talbot 01
    Optics

    Talbot external cavity coherently combines ten laser diodes

    Feb. 1, 2009
    A method of phase-locking an array of ten index-guided tapered laser diodes has been devised by researchers at CNRS and the Alcatel-Tales III-V Lab (both in Palaiseau, France)...