Photonics/Optics

Apparatus and Method for Creating a Photonic Densely Accumulated Ray-Point

NASA's Langley Research Center has discovered a new approach to achieving a laser focal point size much smaller than the wavelength of light used, and smaller than that obtained using conventional micro zone plate lenses. The Photonic Densely Accumulated Ray-poinT (DART) technology relies on phase contrast along with interference phenomena, with or without the use of a micro zone plate lens. Coupled with the extremely small spot size, the technology also provides very high laser energy density at the pseudo focal point surrounded by destructive interference, thereby enabling a range of potential useful applications such as laser processing, lithography, nanofabrication, and optical data storage.

Posted in: Briefs, Photonics, Lasers, Waveguides, Refractory materials
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Optical Fiber Sensors vs. Conventional Electrical Strain Gauges for Infrastructure Monitoring Applications

Public infrastructure, including bridges, pipelines, tunnels, foundations, roadways, dams, etc., is subject to factors that can degrade it or lead to malfunctions. These structural problems can be the result of deterioration, improper construction methods, seismic activity, nearby construction work, etc. Although electrical strain gauges have long been used for monitoring structural changes, they sometimes lack the durability and integrity necessary to provide accurate, actionable information over extended periods. The applications in this white paper demonstrate how optical fiber sensors can offer a variety of economic and performance advantages.

Posted in: White Papers, Fiber Optics, Optics, Sensors
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Laser Diode Modules

BEA Lasers (Elk Grove Village, IL) has introduced two new low-profile additions to their rugged MIL Series of laser diode modules. The new MIL RA Model features a right angle, and the new MIL Compact Model features a straight housing. Both new models utilize a low profile 3/8” rugged laser housing, fitted with a M12 connector, 2 meter long PVC jacketed cable, and integrated power supply. The optional sensor-style bracket, or multi-adjustable “LB” bracket, completes the laser system. The new MIL Series laser diode modules are offered with standard 515nm (green) or standard 635nm (red), with 1mW or 5mW.

Posted in: Products, Products, Lasers & Laser Systems
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Single-Frequency Lasers

LASOS (Jena, Germany) has expanded its range of single-frequency laser sources from the ultra-violet through the red. Wavelength-dependent power levels up to 300 mW are available, with spectral linewidth values less than 1 MHz. Products include diode-pumped solid-state devices from the UV through red. These field-proven sources maintain excellent spectral and power performance for applications including Raman, Holography and Precision Metrology.

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Posted in: Products, Products, Lasers & Laser Systems
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Polymeric Systems Bring Clarity to Optical Applications

Whereas some optical assembly applications require optical clarity across a certain wavelenth, others require an opaque coating. Optical grade epoxies, silicones and UV curable coatings provide the versatility to adhere well to a wide variety of substrates and the critical performance properties necessary. Learn more about optical transmission, refractive indices, temperature and humidity testing, and more, and the roles these measurements in choosing an effective and reliable optical polymer system.

Posted in: White Papers, Photonics
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CUDA Framework for Linear Time-Invariant Control of Adaptive Optics Systems

The predictor used here is computed directly from a measured open-loop disturbance sequence using an efficient subspace identification algorithm.

Current science objectives, such as high-contrast imaging of exoplanets, have led to the development of high-order adaptive optics (AO) systems possessing several thousand deformable mirror (DM) actuators. These systems typically rely on integrator-based control architectures, where the temporal error rejection bandwidth is limited by the computational latency between wavefront measurement and application of the DM commands. In many systems, this latency is the driving factor behind residual wavefront error.

Posted in: Briefs, Imaging, Optics, Photonics, Mirrors, Adaptive control, Architecture, Optics
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Invertible Time Invariant Linear Filtering (InTILF) Method for Pattern Detection and Modeling of Stochastic One- or Two-Dimensional Data

This tool can analyze and model surface metrology data for polishing-tool fabricators.

X-ray astronomy offers the opportunity to observe important phenomena, including the early accretion of massive black holes and detecting diffuse ionized intergalactic gas that is heated to X-ray temperatures (>106). One of the technical challenges facing X-ray astronomy is fabricating optics that are properly shaped and smooth enough to produce quality images. Surface defects on the order of the wavelength of the observed spectrum and up to the size of the optical surface must be polished out of the mirrors without leaving a detectable pattern because the detectable signal is on the order of magnitude of the noise. This leads to a cycle of polishing and metrology that adds time and expense to optics fabrication.

Posted in: Briefs, Imaging, Photonics, Imaging and visualization, Optics, Fabrication, Radiation
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One-Micron (1064-nm) Planar External Cavity Laser (PLANEX)

Ahighly reliable, very low-phase, and low-amplitude-noise laser is required as an oscillator for the LISA mission. A commercial product made by Redfern Integrated Optics met these requirements (1550-nm PLANEX External Cavity Laser), but it operated at 1.5 microns, not the required LISA wavelength of 1 micron. An ultra-low-noise External Cavity Laser was produced at a wavelength of 1 micron, and was integrated in a butterfly package. The goal is to eventually use this laser in the LISA and GRACE-II missions.

Posted in: Briefs, Imaging, Photonics, Lasers, Waveguides, Spacecraft
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Stereoscopic Imaging in Hypersonic Boundary Layers Using Planar Laser-Induced Fluorescence

This technique offers a more complete visualization of high-speed flowfields than standard imaging methods.

Stereoscopic time-resolved visualization of three-dimensional structures in a hypersonic flow was performed for the first time in NASA Langley Research Center’s 31-inch Mach 10 Air Tunnel. Nitric oxide (NO) was seeded into hypersonic boundary layer flows that were designed to transition from laminar to turbulent. A laser excitation and multiple-camera imaging scheme was used to obtain raw images containing three-dimensional spatial information. The images were processed in a computer visualization environment to provide stereoscopic image pairs that could be viewed several ways, including using the cross-eyed viewing method, with the aid of a stereoscope, as animated image pairs (i.e., wiggle stereoscopy), or as anaglyph images through conventional red/blue 3D glasses.

Posted in: Briefs, Imaging, Photonics, Computational fluid dynamics, Imaging and visualization, Lasers
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Compact, Lightweight, Athermal, Nanocomposite Telescopes with Freeform Optics

Small space missions such as CubeSats frequently require telescopes with highly sophisticated optical systems that are also low in mass and cost. The very limited spacecraft volume and mass limits also preclude adjustments to maintain critical alignment with change in temperature. Existing systems, especially those that employ folded optical paths with freeform optics, are expensive to fabricate. The optics, and support and metering structures, are also heavy due to the use of high-density material such as glass, aluminum, or nickel.

Posted in: Briefs, Imaging, Optics, Photonics, Downsizing, Optics, Nanomaterials, Satellites
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