Search

NASA Goddard Space Flight Center has developed a coherent optical transistor incorporating a coherent gain mechanism, resulting in larger and higher intensity signals present in optical logic systems. Moreover, the gain mechanism only adds a small amount of thermal energy, making the entire transistor easier to cool, reducing the overall size, weight, and power requirements.

The Coating-Less Non-Planar Ring Oscillator Laser utilizes a monolithic laser crystal, whose surfaces are precisely polished to form an optical cavity within the crystal, solely using total internal reflection (TIR). All surfaces of the laser use TIR, eliminating the need for any optical coatings. Frustrated TIR (FTIR) is used for the outer surface. The output coupler satisfies TIR, as does other reflection surfaces, which has a large enough angle of incidence for the internal ray. The ring resonator of the laser is also designed to be nonplanar, meaning the optical path is not on a flat plane. The Coating-Less Non-Planar Ring Oscillator Laser achieves high stability, high output power, and high reliability both in continuous wave mode and pulsed mode. It does not use any thin film optical coatings. Since there are no thin-film optical coatings in the laser cavity, one can expect more reliable laser operation and higher output power. Also, since it has a traveling wave cavity with internal polarization rotation mechanism (through the non-planar optical path), the output mode is ensured to be single longitudinal mode and stable. It also eliminates the possibility of damage due to the transition between the multi-mode and single-mode oscillation. A traditional NPRO crystal may be used as the laser crystal. Coupling of the FTIR can be adjusted to make an air-gap cube beam splitter, where the distance between the two surfaces determines the FTIR coupling strength. The laser crystal can be used both for Q-switching and continuous mode.

The Video Acuity metric is designed to provide a unique and meaningful measurement of the quality of a video system. The automated system for measuring video acuity is based on a model of human letter recognition. The Video Acuity measurement system is comprised of a camera and associated optics and sensor, processing elements including digital compression, transmission over an electronic network, and an electronic display for viewing of the display by a human viewer. The quality of a video system impacts the ability of the human viewer to perform public safety tasks, such as reading of automobile license plates, recognition of faces, and recognition of handheld weapons. The Video Acuity metric can accurately measure the effects of sampling, blur, noise, quantization, compression, geometric distortion, and other effects. This is because it does not rely on any particular theoretical model of imaging, but simply measures the performance in a task that incorporates essential aspects of human use of video, notably recognition of patterns and objects. Because the metric is structurally identical to human visual acuity, the numbers that it yields have immediate and concrete meaning. Furthermore, they can be related to the human visual acuity needed to do the task. The Video Acuity measurement system uses different sets of optotypes and uses automated letter recognition to simulate the human observer.

NASA Goddard Space Flight Center has developed a configurable phase mirror system that can address likely obstacles in space optical communications. Through using miniature adjustable mirrors and programmed phase delays to diffract a single communication beam, numerous diffracted beams can be sent to other satellites in various directions for communication and tracking. The initial laser beams wave profile can be dynamically regulated through a fast Fourier transform (FFT) so that when it reaches its desired destination, it forms an intended illuminated spot at the target satellite. Since all the diffracted beams share the same phase mirror, the antenna gain needed to broadcast these beams does not require a multiplied aperture.

NASA Goddard Space Flight Center (GSFC) has developed a new 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 non-conventional radar techniques, known as Digital Beamforming Synthetic Aperture Radar Multi-mode Operation (DBSAR). DBSAR is an L-Band airborne radar that combines advanced radar technology with the ability to implement multimode remote sensing techniques, including several variations of SAR, scatterometry over multiple beams, and an altimeter mode. The Multiple channel data acquired with a digital beamformer systems allows the synthesis of beams over separate areas of the antenna, effectively dividing the single antenna into two antennas. The InSAR technique is then achieved by generating interferograms from images collected with each of the antennas. Since the technique is performed on the data, it allows for synthesizing beams in different directions (or look angles) and performs interferometry over large areas. Digital Beamforming Interferometry has potential in many areas of radar applications. For example, NASA GSFC innovators developed the first P-Band Digital Beamforming Polarimetric Interferometric SAR Instrument to measure ecosystem structure, biomass, and surface water.

NASA Goddard Space Flight Center's has developed a non-scanning, 3D imaging laser system that uses a simple lens system to simultaneously generate a one-dimensional or two-dimensional array of optical (light) spots to illuminate an object, surface or image to generate a topographic profile. The system includes a microlens array configured in combination with a spherical lens to generate a uniform array for a two dimensional detector, an optical receiver, and a pulsed laser as the transmitter light source. The pulsed laser travels to and from the light source and the object. A fraction of the light is imaged using the optical detector, and a threshold detector is used to determine the time of day when the pulse arrived at the detector (using picosecond to nanosecond precision). Distance information can be determined for each pixel in the array, which can then be displayed to form a three-dimensional image. Real-time three-dimensional images are produced with the system at television frame rates (30 frames per second) or higher. Alternate embodiments of this innovation include the use of a light emitting diode in place of a pulsed laser, and/or a macrolens array in place of a microlens.

NASA Goddard Space Flight Center has developed a 3D lidar system that consists of microelectromechanical systems (MEMS) beam steering, high performance reconfigurable computing, and an in-depth understanding of systems level integration. Kodiak combines a 3D MEMS scanning lidar with a long range narrow FOV telescope to produce a flexible and capable space flight ranging system. Also included is SpaceCube-level processing power to host a variety of algorithms enabling sensing and 6 degrees of freedom.

NASA's gas sensor was originally developed for the storage of volatile liquids and high-pressure gases in outer space in order to facilitate space travel. The innovation has a diverse array of applications beyond aerospace, including cryogenic environments, pressurized or vacuum conditions, and hazardous locations. The sensor system is composed of 1) a fiber-coupled laser light source, 2) a fiber-coupled photodiode detector, and 3) an optical interferometer. The non-intrusive sensor employs a number of optical techniques to measure gas density, temperature, type of species present, and concentration of various species. When the sensor is placed in the area where a gas leak may be present, gas density is detected and recorded as a result of changes in light transmission through the fiber. Changes in the density of gas in the test region cause corresponding changes in the intensity output onto a photodiode detector. This process provides a real-time, temporal history of a leak. Gas temperature is determined by placing an optical fiber along the length of a structure for in-situ measurements. The type of gas species present can be determined by using optical line emission spectrometry. The light-based sensor uses these interferometric and spectroscopic techniques to obtain real-time, in-situ measurements that have been successfully tested in environments with a pressure range of 20 mtorr to 760 mtorr. Commercially available gas detection methods are limited in several ways. Vacuum gauges can detect only certain gases, and they have a limited operational range. Mass spectrometer systems are able to perform well, but their size, bulk, and use of high voltage, which can potentially cause arcing and ignition of combustible propellants, severely limit their usefulness. NASA's compact gas detection sensor has numerous advantages over other state-of-the-art detection techniques. Because the sensor is rugged, compact, and lightweight, it can be used in small, remote areas where other devices will not fit. It has no electronic ignition device, making the system suitable for use in explosive or hazardous environments. The system measures gas density, temperature, type, and concentration in real time, providing critical information on both the severity and location of the leak, all while consuming minimal power at very low cost.

Conventional neutron beam experiments demand high fluxes that can only be obtained at research facilities equipped with a reactor source and neutron optics. However, access to these facilities is limited. The NASA technology uses grazing incidence reflective optics to produce focused beams of neutrons (Figure 1) from compact commercially available sources, resulting in higher flux concentrations. Neutrons are doubly reflected off of a parabolic and hyperbolic mirror at a sufficiently small angle, creating neutron beams that are convergent, divergent, or parallel. Neutron flux can be increased by concentrically nesting mirrors with the same focal length and curvature, resulting in a convergence of multiple neutron beams at a single focal point. The improved flux from the compact source may be used for non-destructive testing, imaging, and materials analysis. The grazing incidence neutron optic mirrors are fabricated using an electroformed nickel replication technique developed by NASA and the Harvard-Smithsonian Center for Astrophysics (Figure 2). A machined aluminum mandrel is super-polished to a surface roughness of 3-4 angstroms root mean square and plated with layers of highly reflective nickel-cobalt alloy. Residual stresses that can cause mirror warping are eliminated by periodically reversing the anode and cathode polarity of the electroplating system, resulting in a deformation-free surface. The fabrication process has been used to produce 0.5 meter and 1.0 meter lenses.