Special Coverage

Home

Optical Displacement Sensor for Sub- Hertz Applications

A document discusses a sensor made from off-the-shelf electro-optical photodiodes and electronics that achieves 20 nm/(Hz)1/2 displacement sensitivity at 1 mHz. This innovation was created using a fiber-coupled laser diode (or Nd:YAG) through a collimator and an aperture as the illumination source. Together with a germanium quad photodiode, the above-mentioned displacement sensor sensitivities have been achieved. This system was designed to aid the Laser Interferometer Space Antenna (LISA) with microthruster tests and to be a backup sensor for monitoring the relative position between a proof mass and a spacecraft for drag-free navigation. The optical displacement sensor can be used to monitor any small displacement from a remote location with minimal invasion on the system.

Posted in: Physical Sciences, Photonics, Briefs, TSP

Read More >>

Sensing a Changing Chemical Mixture Using an Electronic Nose

ASIC may enable continuous, high-speed monitoring. A method of using an electronic nose to detect an airborne mixture of known chemical compounds and measure the temporally varying concentrations of the individual compounds is undergoing development. In a typical intended application, the method would be used to monitor the air in an inhabited space (e.g., the interior of a building) for the release of solvents, toxic fumes, and other compounds that are regarded as contaminants. At the present state of development, the method affords a capability for identifying and quantitating one or two compounds that are members of a set of some number (typically of the order of a dozen) known compounds. In principle, the method could be extended to enable monitoring of more than two compounds.

Posted in: Physical Sciences, Briefs

Read More >>

Optimized Geometry for Superconducting Sensing Coils

Design would minimize measurement time in magnetic resonance imaging. An optimized geometry has been proposed for superconducting sensing coils that are used in conjunction with superconducting quantum interference devices (SQUIDs) in magnetic resonance imaging (MRI), magneto- encephalography (MEG), and related applications in which magnetic fields of small dipoles are detected. In designing a coil of this type, as in designing other sensing coils, one seeks to maximize the sensitivity of the detector of which the coil is a part, subject to geometric constraints arising from the proximity of other required equipment. In MRI or MEG, the main benefit of maximizing the sensitivity would be to enable minimization of measurement time.

Posted in: Physical Sciences, Briefs, TSP

Read More >>

Generic Helicopter-Based Testbed for Surface Terrain Imaging Sensors

This flexible field test system is designed for sensors that require an aerial test platform. To be certain that a candidate sensor system will perform as expected during missions, we have developed a field test system and have executed test flights with a helicopter- mounted sensor platform over desert terrains, which simulate Lunar features. A key advantage to this approach is that different sensors can be tested and characterized in an environment relevant to the flight needs prior to flight. Testing the various sensors required the development of a field test system, including an instrument to validate the “truth” of the sensor system under test. The field test system was designed to be flexible enough to cover the test needs of many sensors (lidar, radar, cameras) that require an aerial test platform, including helicopters, airplanes, unmanned aerial vehicles (UAV), or balloons. To validate the performance of the sensor under test, the dynamics of the test platform must be known with sufficient accuracy to provide accurate models for input into algorithm development. The test system provides support equipment to measure the dynamics of the field test sensor platform, and allow computation of the “truth” position, velocity, attitude, and time.

Posted in: Physical Sciences, Briefs

Read More >>

Induction Charge Detector With Multiple Sensing Stages

Standard errors and detection limits are reduced by use of multiple stages. An induction charge detector with multiple sensing stages has been conceived for use in characterizing sprayed droplets, dust particles, large ionized molecules, and the like. Like related prior single-stage devices, each stage yields a measurement of the electric charge and the time of flight of the particle. In effect, an n-stage sensor yields n independent sets of such measurements from the same particle. The benefit of doing this is to increase the effective signal- to-noise ratio and thereby lower the charge-detection limit and the standard error of the charge measurement.

Posted in: Physical Sciences, Briefs

Read More >>

Dr. John Mather, Chief Scientist for the Science Mission Directorate

NASA Headquarters, Washington, DC Using NASA’s Cosmic Background Explorer (COBE) satellite to measure microwaves and infrared light that originated with the formation of the universe, Dr. John C. Mather helped verify the validity of the Big Bang theory. Recently named to head up the Office of the Chief Scientist for the Science Mission Directorate at NASA Headquarters in Washington, DC, Dr. Mather was a co-recipient of the 2006 Nobel Prize in Physics.

Posted in: Who's Who

Read More >>

Microwavable Packaging That Produces Authentic Grilled Foods

This organization wants to create authentic grilled foods in a home microwave oven with typical microwave food preparation times and convenience. Authentic grilled foods combine a slightly charred taste with a less fatty, cleaner feel, and the appearance of grill marks seared by high heat into the surface of the food. This need seeks to reproduce as closely as possible the texture and quality of perfectly grilled foods. Respond to this TechNeed at: Email: nasatech@yet2.com Phone: 781-972-0600

Posted in: NASA Tech Needs

Read More >>