Special Coverage

Technique Provides Security for Multi-Robot Systems
Bringing New Vision to Laser Material Processing Systems
NASA Tests Lasers’ Ability to Transmit Data from Space
Converting from Hydraulic Cylinders to Electric Actuators
Automating Optimization and Design Tasks Across Disciplines
Vibration Tables Shake Up Aerospace and Car Testing
Supercomputer Cooling System Uses Refrigerant to Replace Water
Computer Chips Calculate and Store in an Integrated Unit
Electron-to-Photon Communication for Quantum Computing

Systems and Methods for Mirror Mounting with Minimized Distortion

The use of larger, lighter, and more precise space optics requires not only a means of manufacture, but also a means of spacecraft integration and performance verification. Engineers at NASA's Goddard Space Flight Center (GSFC) have demonstrated a process capable of producing a high-precision, mounted, lightweight mirror, and have validated its on-orbit figure. This effort included the design of a mount capable of surviving the launch environment of a sounding rocket, as well as a mounting process that did not introduce performance-degrading figure distortion. Additionally, analysis techniques were developed and adapted to address the challenges in measuring an optic that exceeds its figure specification under the strain of its own weight.

Posted in: Briefs, Photonics, Mirrors, Optics, Mountings, Durability, Lightweighting
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Improved Approach to Exoplanet Coronagraphy

Visible nulling coronagraphy and interferometry requires that the wavefront errors be held to unprecedented precision in the presence of environmental disturbances. A Null Diversity algorithm is used to first attain the precision, but it does not execute at high enough temporal bandwidth to hold the precision for long periods of time (hours). The environmental changes, mostly vibration and jitter with some thermal drift, can be rapidly varying and thus require a fast control algorithm. To perform rapid control, an algorithm, based upon a series of approximations, has been developed and simulated at NASA Goddard Space Flight Center for the sensing and control, in closed loop, of extremely precise wave-front errors in an interferometer. It operates over the range of ~5 nanometers rms down to <100 picometers rms in closed loop at high bandwidth (~20 Hz) and is used to hold (i.e. maintain) the requisite wavefront error.

Posted in: Briefs, Photonics, Mathematical models, Lasers, Vibration
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Apparatus and Method for a Light Direction Sensor

This invention, developed at NASA's Goddard Space Flight Center, was originally conceived as a high-accuracy, high-sensitivity, bi-axial Sun angle sensor, but has also been proposed for applications involving the general field of precisely measuring the direction in which light travels toward the sensor. It has applications in spacecraft navigation, formation flying in space, space beacons, and automotive collision avoidance.

Posted in: Briefs, Photonics, Measurements, Sensors and actuators, Sun and solar
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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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