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Laser Subdivision of the Genesis Concentrator Target Sample 60000

Lyndon B. Johnson Space Center, Houston, Texas A need arose for approximately 1 cm2 of a diamond-like-carbon (DLC) concentrator target for the analysis of solar wind nitrogen isotopes. The original target was a circular quadrant with a radius of 3.1 cm; however, the piece did not survive intact when the spacecraft suffered an anomalous landing upon returning to Earth. An estimated 75% of the DLC target was recovered in at least 18 fragments. The largest fragment, Genesis sample 60000, was designated for this allocation, and is the first sample to be subdivided using a laser scribing system. Laser subdivision has associated risks, including thermal diffusion of the implant if heating occurs, and unintended breakage during cleavage. In order to minimize the possibility of unintended breakage of the actual target wafer during subdivision, a careful detailed study involving numerous laser scribing plans was undertaken. The innovation described here involves the results of this study that yielded a cutting plan essentially guaranteeing ~100% cleaving success of this precious space-exposed wafer.

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Fabrication of an Integrated Photonic Waveguide Joint in Micromachined Silicon

This technology could be used in any MEMS or micromachined structure that requires multiple levels of topography. Goddard Space Flight Center, Greenbelt, Maryland High-aspect-ratio silicon structures are necessary components in many MEMS (microelectromechanical systems). Aspect ratio is defined as the ratio of the height of the structure to its lateral width. The structures are typically fabricated through bulk micromachining steps such as deep reactive ion etching. In some cases, multiple levels of high-aspect-ratio structures are required. For instance, one may want to etch completely through a silicon wafer to thermally isolate a bolometer or provide waveguide coupling to an antenna defined on an insulating membrane, and at the same time have integrated high-topology structures required for microwave coupling or filtering. Definition of the structures typically uses photolithographic technology. But for high-aspect-ratio structures, spin cast resist becomes difficult to incorporate due to the non-uniform thickness of the resist around tall structures. One can cast very thick layers of photoresist, but this limits the minimum feature size, and additionally, very thick layers of photoresist are difficult to work with due to solvent release and moisture that can cause the resist to crack or swell. For electromagnetic reasons, the structures would preferably be made from conductive material such as metal or degeneratively doped silicon. The objective of this work was to incorporate multiple levels of conductive high-aspectratio structures with standard micromachining processes.

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Very Large Inflatable Antenna Structures

This methodology enables production of very large, but lightweight, structures in space. Langley Research Center, Hampton, Virginia Future space exploration past Earth orbit has a significant need for manufacturing in space beyond simple assembly of prefabricated parts. The next generation of very large aperture antennas will exceed the size achievable with conventional folding mesh technologies and new concepts are needed to support football-field-size structures. Technologies to address the problem have been developed using the formation of polyurethanes in a vacuum environment. Large inflatable structures can be stabilized by the formation of polyurethane foams of controlled density. For use in a vacuum environment, the availability of oligomeric precursors is important. Low-molecular-weight components would immediately evaporate, changing the stoichiometry of the reaction and potentially contaminate a space environment, but high-molecular-weight precursors have a much more limited range of properties.

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Products of Tomorrow: April 2016

The technologies NASA develops don’t just blast off into space. They also improve our lives here on Earth. Life-saving search-and-rescue tools, implantable medical devices, advances in commercial aircraft safety, increased accuracy in weather forecasting, and the miniature cameras in our cellphones are just some of the examples of NASA-developed technology used in products today.

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Linear Motor

Nippon Pulse America (Radford, VA) released the SL083 scaleless linear motor with a built-in linear encoder for positioning applications that would benefit from the repeatability, reliability, and robustness of a linear motor, with up to 5 μm in resolution. The motor consists of a tubular stainless steel shaft and a non-contact forcer. It requires no lubrication, and features a non-critical air gap that eliminates variation in the force. The housing is made of non-magnetic aluminum.

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Panel-Mount Piezo Drives

The Ndrive QLe digital, panel-mount nanopositioning piezo drives from Aerotech (Pittsburgh, PA) are designed for use with the Aerotech Automation 3200 (A3200) motion controller. The drives enable coordinated motion between piezo stages and servo axes at higher rates than other controller/drive products. Featuring a dual-core, 456-MHz, floating-point DSP, the drives feature position latching and single-axis or multi-axis position synchronized output (PSO) to generate pulses based on actual position feedback.

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Encoders

Celera Motion (Bedford, MA) introduced the MicroE Veratus™ Series encoders incorporating VeraPath™ technology. All interpolation, automatic gain control (AGC), and signal processing is performed in the sensor head that measures 35 × 13.5 × 10 mm. Interpolation in the sensor head provides resolution from 5 μm to 20 nm for linear applications, with speeds up to 5 m/s. The encoders feature multiple mounting configurations, industry-standard analog and digital incremental encoder outputs, built-in limits, flexible index selection, and status LED in the sensor head.

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