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Raman Spectrometer Monitors Multiple Reaction Sites with Doubled Dispersion

Compact f/2.4 design efficiently handles large numbers of optical fibers at the entrance aperture. Headwall Photonics, Fitchburg, Massachusetts Raman spectroscopy has risen to the top of a short list of technologies for identifying substances with high specificity. As a result, Raman spectrometers with high spectral resolution, high spatial resolution, high throughput, and small footprints are in high demand. Utilizing holographic diffraction gratings technology, Headwall Photonics has developed an imaging spectrometer that satisfies these performance demands through a retro-reflective concentric design utilizing the optimized properties of an advanced, highly efficient convex grating (see Figure 1).

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Seeing (infra)Red: InGaAs Conquers Imaging, Sensing, Telecom

Indium gallium arsenide, or InGaAs, is an alloy of gallium arsenide and indium arsenide. In a more general sense, it belongs to the InGaAsP quaternary system that consists of alloys of indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), and gallium phosphide (GaP). As gallium and indium belong to Group III of the Periodic Table, and arsenic and phosphorus belong to Group V, these binary materials and their alloys are all III-V compound semiconductors.

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Spectral vs. Coherent Beam Combining: How Do They Compare?

Partial reflectors in interferometers and polarization-sensitive devices (beam splitters used in reverse) such as beam-splitting cubes are common examples of systems that combine two beams (adding beams so that they are co-linear). While these components perform beam combining, they typically are inefficient and/or limited in the number of beams that can be combined. Polarization beam combining, for instance, only works with two beams because the light has only two distinguishable states.

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Optics Program Modified for Multithreaded Parallel Computing

NASA’s Jet Propulsion Laboratory, Pasadena, California A powerful high-performance computer program for simulating and analyzing adaptive and controlled optical systems has been developed by modifying the serial version of the Modeling and Analysis for Controlled Optical Systems (MACOS) program to impart capabilities for multithreaded parallel processing on computing systems ranging from supercomputers down to Symmetric Multiprocessing (SMP) personal computers. The modifications included the incorporation of OpenMP, a portable and widely supported application interface software, that can be used to explicitly add multithreaded parallelism to an application program under a shared-memory programming model. OpenMP was applied to parallelize ray-tracing calculations, one of the major computing components in MACOS. Multithreading is also used in the diffraction propagation of light in MACOS based on p-threads [POSIX Thread, (where “POSIX” signifies a portable operating system for UNIX)]. In tests of the parallelized version of MACOS, the speedup in ray-tracing calculations was found to be linear, or proportional to the number of processors, while the speedup in diffraction calculations ranged from 50 to 60 percent, depending on the type and number of processors. The parallelized version of MACOS is portable, and, to the user, its interface is basically the same as that of the original serial version of MACOS.

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Enhanced-Contrast Viewing of White-Hot Objects in Furnaces

Band-pass- and polarization-filtered laser light exceeds polarization-suppressed blackbody light. Marshall Space Flight Center, Alabama An apparatus denoted a laser image contrast enhancement system (LICES) increases the contrast with which one can view a target glowing with blackbody radiation (a white-hot object) against a background of blackbody radiation in a furnace at a temperature as high as ≈1,500 °C. The apparatus utilizes a combination of narrowband illumination, along with band-pass filtering and polarization filtering to pass illumination reflected by the target while suppressing blackbody light from both the object and its background.

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Dual-Laser-Pulse Ignition

This scheme provides a more reliable ignition source and more efficient energy delivery than a single-pulse format. Marshall Space Flight Center, Alabama A dual-pulse laser (DPL) technique has been demonstrated for generating laser-induced sparks (LIS) to ignite fuels. The technique was originally intended to be applied to the ignition of rocket propellants, but may also be applicable to ignition in terrestrial settings in which electric igniters may not be suitable. Laser igniters have been sought as alternatives to such conventional devices as electrical spark plugs and torch igniters for the following main reasons:

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Few-Mode Whispering-Gallery-Mode Resonators

Simple structures function similarly to single-mode optical fibers. NASA’s Jet Propulsion Laboratory, Pasadena, California Whispering-gallery-mode (WGM) optical resonators of a type now under development are designed to support few well-defined waveguide modes. In the simplest case, a resonator of this type would support one equatorial family of WGMs; in a more complex case, such a resonator would be made to support two, three, or some other specified finite number of modes. Such a resonator can be made of almost any transparent material commonly used in optics. The nature of the supported modes does not depend on which material is used, and the geometrical dispersion of this resonator is much smaller than that of a typical prior WGM resonator. Moreover, in principle, many such resonators could be fabricated as integral parts of a single chip.

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