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

Digital Beamforming Interferometry

This technology effectively divides a single antenna into two antennas.

NASA Goddard Space Flight Center has developed a new radar approach that uses a single phased array antenna and a single-pass configuration to generate interferograms, known as Digital Beamforming Interferometry. A digital beamforming radar system allows the implementation of nonconventional radar techniques, known as Digital Beamforming Synthetic Aperture Radar Multimode Operation (DBSAR).

Posted in: Briefs, Photonics
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Additive-Manufactured, Very Lightweight, Diamond Turned Aspheric Mirror

Industrial-grade, lightweight mirrors used in military and aeronautics have tight specifications brought on by demanding performance parameters. For example, a mirror that is used in an orbiting telescope would have to be extremely lightweight, stiff, and be configured to operate in extreme temperatures. These parameters traditionally work against each other. A material that is stiff is typically heavy, and a mirror that is lightweight and machinable may greatly distort when exposed to extreme heat or cold. Furthermore, materials that fit some of these parameters may not be easily machined to create a mirror — an art that requires high-precision tooling.

Posted in: Briefs, Photonics
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Development of a Sodium LiDAR for Spaceborne Missions

Laser and electro-optic technologies are under development to remotely measure sodium (Na) by adapting existing LiDAR technology with spaceflight heritage. The developed instrumentation will serve as the core for planning a heliophysics mission targeted to study the composition and dynamics of Earth's mesosphere based on a spaceborne LiDAR that will measure the mesospheric Na layer.

Posted in: Briefs, Photonics
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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, Photonics
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Development of Sodium Lidar for Spaceborne Missions

The metal layers at mesospheric altitudes are excellent tracers of neutral atmosphere dynamics, and have been used since the 1960s to study the chemistry and dynamics of the mesosphere. Ablation from meteors is believed to be the chief source of metals such as Na, Mg, K, Fe, and Ca in the middle atmosphere. Due to its relative abundance, large backscatter cross-section, and visible atomic transition, sodium (Na) has been used extensively for lidar studies of the mesosphere.

Posted in: Briefs, Photonics, Lidar, Weather and climate, Metals, Sodium, Test procedures
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Additive-Manufactured, Very Lightweight, Diamond Turned Aspheric Mirror

Industrial-grade, lightweight mirrors used in military and aeronautics have tight specifications brought on by demanding performance parameters. For example, a mirror that is used in an orbiting telescope would have to be extremely lightweight, stiff, and be configured to operate in extreme temperatures. These parameters traditionally work against each other. A material that is stiff is typically heavy, and a mirror that is lightweight and machinable may greatly distort when exposed to extreme heat or cold. Furthermore, materials that fit some of these parameters may not be easily machined to create a mirror, an art that requires high-precision tooling.

Posted in: Briefs, Photonics, Mirrors, Additive manufacturing, Lightweight materials
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Partially Transparent Circular Mask to Suppress Narrowband Laser Light

The evolved Laser Interferometry Space Antenna (eLISA) is the implementation of the original Laser Interferometry Space Antenna (LISA) concept that will be proposed for the European Space Agency's (ESA) L.3 Cosmic Visions opportunity. The eLISA observatory uses lasers to range between pairs of freely falling test masses in adjacent, widely separated spacecraft. The measurement is made continuously, requiring simultaneous transmission and reception of a 1064-nm laser beam through an optical telescope.

Posted in: Briefs, Photonics, Measurements, Antennas, Lasers, Spacecraft
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Characterizing Richness of Previously Unmapped Terrain and Estimating Its Impact on Navigation Performance Using 3D Range Sensors in Flight

Landers to large planetary bodies such as Mars typically use a secondary reconnaissance spacecraft to generate high-fidelity 3D terrain maps that are subsequently used for landing site selection and creating onboard maps for terrain-relative navigation systems. This luxury does not exist with small primitive bodies such as comets and asteroids. For these bodies, the landing spacecraft has to perform the 3D mapping and, with possible help from ground control, choose a feasible landing site. To enable this operation, the spacecraft would need to carry a 3D ranging sensor system such as a LIDAR. With the spacecraft placed in extended mapping orbits, 3D range measurement data is then used to create a shape model of the object. Terrain-based navigation schemes that employ cameras could then be used to image, detect, match, and track features against the map database to provide a 6-degrees-of-freedom (DOF) navigation solution during descent. Camera-based systems, however, are not robust to lighting variations, and do not provide a direct 3D position/range feedback.

Posted in: Briefs, Photonics, Cartography, Terrain, Entry, descent, and landing, Spacecraft
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Micro-Fresnel Zone Plate Optical Devices Using Densely Accumulated Ray Points

NASA Langley Research Center has developed a novel approach for a high-density optical data storage system to advance the typical capabilities of an optical data storage system. Operating at any laser wavelength from infrared (IR), visible, ultraviolet (UV), and X-ray regimes, the NASA technology utilizes special beam focusing techniques to achieve extremely short focal lengths and ultra-small spot sizes. The technology could be used with any laser wavelength and soft X-ray regime, and can be adapted to take advantage of any optical media. The high-density data storage capability is solely a function of the reduced laser/X-ray spot size.

Posted in: Briefs, Photonics, Lasers, Optics, Waveguides, Data management
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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 highorder 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, Photonics, Mirrors, Adaptive control, Architecture, Computer software and hardware, Optics, Sensors and actuators
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