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NASA NTRS2018

Optical Communication Activities Through the Laser-Enhanced Mission Communications Navigation and Operational Services (LEMNOS) Office

Seas, Antonios A.↗

NASA NTRS1993

A motion detection system for AXAF X-ray ground testing

The concept, implementation, and performance of the motion detection system (MDS) designed as a diagnostic for X-ray ground testing for AXAF are described. The purpose of the MDS is to measure the magnitude of a relative rigid body motion among the AXAF test optic, the X-ray source, and X-ray focal plane detector. The MDS consists of a point source, lens, centroid detector, transimpedance amplifier, and computer system. Measurement of the centroid position of the image of the optical point source provides a direct measure of the motions of the X-ray optical system. The outputs from the detector and filter/amplifier are digitized and processed using the calibration with a 50 Hz bandwidth to give the centroid's location on the detector. Resolution of 0.008 arcsec has been achieved by this system. Data illustrating the performance of the motion detection system are also presented.

Arenberg, Jonathan W.↗

NASA NTRS1976

Aerosol size distributions - Remote determination from air-borne measurements of the solar aureole

Aerosol-size distributions were determined remotely using an airborne scanning photometer. This instrument consists of a sunshade, optics, and a large-dynamic-range photodetector-amplifier system that scans about the vertical, recording both the direct attenuated solar beam and the diffuse sky radiance in the almucantar of the sun at an effective wavelength of 0.54 micron. Inversion of the measured radiances determined aerosol radii from approximately 0.2 to 8.0 microns. Data were taken during flights over western Lake Superior and southwestern Wisconsin. Inverted aerosol-size distributions are compared with results obtained by other methods.

Twitty, J. T.↗

NASA NTRS1983

The High Spectral Resolution Lidar

The High Spectral Resolution Lidar (HSRL) system was developed for the remote measurement of atmospheric optical properties. Measurements are obtained by the separation of the backscattered signal into aerosol and molecular channels using a high spectral resolution Fabry-Perot optical interferometer to separate the aerosol contributions to backscatter near the laser wavelength from the Doppler-shifted molecular component of the backscatter. The transmitter consists of an optically pumped pulsed dye laser of the oscillator-amplifier design which emits at 467.88 nm, with a bandwidth of less than 0.3 pm. The transmitter and receiver share a common Schmidt-Cassegrain telescope, although they do not share the same field stop, but rather two conjugate stops. The HSRL system uses a computer-controlled dual-channel photon-counting data acquisition system providing for stable measurements at very low power levels and an excellent dynamic range. The system has been used to obtain airborne measurements of height profiles of aerosol and molecular backscatter cross sections.

Eloranta, E. W.↗

NASA NTRS1989

Telecommunications technology development for the Deep Space Network

The telecommunications technology that is currently being developed for the Deep Space Network (DSN), a system providing communications and navigation support for NASA's deep space missions, is discussed. The major areas of development include Ka-band (32 GHz) technology, beam waveguide antennas, low-noise amplifiers, coding, navigation techniques, high-power transmitters, and optical technology. The expected payoffs of the new technology during the mid-1990's and later are examined.

Yuen, J. H.↗

NASA NTRS1990

Preparation of a second station for the measurement of solar oscillations of low degree 'l'

An observing station to detect low-degree global solar oscillations is already operational at the Jet Propulsion Laboratory. A second station for continuative measurements of such oscillations has recently been installed and successfully tested in Rome. The high transmission and stability of the magneto-optical filter (MOF) coupled with the lock-in amplifier technique allow analog and real-time detection of oscillation modes with a noise level of only a few cm/s. Observing runs and estimates of the signal-to-noise ratio are shown in time and frequency domains. Routine observations will establish whether the MOF sensitivity and stability are suitable for the detection of stellar oscillations.

Cacciani, A.↗

NASA NTRS1993

Optical beam forming techniques for phased array antennas

Conventional phased array antennas using waveguide or coax for signal distribution are impractical for large scale implementation on satellites or spacecraft because they exhibit prohibitively large system size, heavy weight, high attenuation loss, limited bandwidth, sensitivity to electromagnetic interference (EMI) temperature drifts and phase instability. However, optical beam forming systems are smaller, lighter, and more flexible. Three optical beam forming techniques are identified as applicable to large spaceborne phased array antennas. They are (1) the optical fiber replacement of conventional RF phased array distribution and control components, (2) spatial beam forming, and (3) optical beam splitting with integrated quasi-optical components. The optical fiber replacement and the spatial beam forming approaches were pursued by many organizations. Two new optical beam forming architectures are presented. Both architectures involve monolithic integration of the antenna radiating elements with quasi-optical grid detector arrays. The advantages of the grid detector array in the optical process are the higher power handling capability and the dynamic range. One architecture involves a modified version of the original spatial beam forming approach. The basic difference is the spatial light modulator (SLM) device for controlling the aperture field distribution. The original liquid crystal light valve SLM is replaced by an optical shuffling SLM, which was demonstrated for the 'smart pixel' technology. The advantages are the capability of generating the agile beams of a phased array antenna and to provide simultaneous transmit and receive functions. The second architecture considered is the optical beam splitting approach. This architecture involves an alternative amplitude control for each antenna element with an optical beam power divider comprised of mirrors and beam splitters. It also implements the quasi-optical grid phase shifter for phase control and grid amplifier for RF power. The advantages are no SLM is required for this approach, and the complete antenna system is capable of full monolithic integration.

Wu, Te-Kao↗

NASA NTRS2015

Pyrometer

A non-contact pyrometer and method for calibrating the same are provided. The pyrometer includes a radiation sensor configured to measure at least a portion of a radiance signal emitted from a target medium and output a voltage that is a function of an average of the absorbed radiance signal, and an optical window disposed proximate the radiation sensor and configured to control a wavelength range of the radiance signal that reaches the radiation sensor. The pyrometer may further include a reflective enclosure configured to receive the target medium therein, wherein the radiation sensor and the optical window are disposed within the reflective enclosure, an amplifier in communication with an output of the radiation sensor, and a data acquisition system in communication with an output of the amplifier.

Quince, Asia N.↗

NASA NTRS2018

Optical Communications Systems for NASA's Human Space Flight Missions

The Laser-Enhanced Mission Communications Navigation and Operational Services (LEMNOS) office at Goddard Space Flight Center (GSFC) manages two NASA optical communication related projects, the Orion EM-2 Optical Communications Terminal (O2O) and the Integrated Laser Communications Relay Demonstration (LCRD) Low-Earth Orbit (LEO) User Modem and Amplifier Terminal (ILLUMA-T) projects. The main goal of LEMNOS is the advancement and implementation of optical communications systems and technologies for NASA missions. The O2O mission is sponsored by NASA's Human Exploration and Operations (HEO) Mission Directorate. The O2O project will provide optical communications capability to the Orion series of spacecraft, starting with the demonstration of operational utility on EM-2. It will be the first time a human exploration mission will rely on optical communications for its high-bandwidth link. ILLUMA-T is sponsored by the Space Communications and Navigation (SCaN) Program Office. It is destined for the International Space Station (ISS) as an external payload attached to the Japanese Experiment Module - Exposed Facility (JEM-EF). The ILLUMA-T project is developing an optical communications user terminal to demonstrate high bandwidth data transfer between LEO and the ground through the geosynchronous LCRD relay. ILLUMA-T will be the first demonstration of a LEO user of the LCRD system, pointing and tracking from a moving spacecraft at LEO to GEO satellite and vice versa, end-to-end operational utility of optical communications, and 51 Mbps forward link to ISS from ground. Both projects are collaborations between GSFC, Massachusetts Institute of Technology â€" Lincoln Laboratory (MIT-LL), and a number of contractors.

Lasercom↗

NASA NTRS2018

Optical Communications Systems for NASA's Human Space Flight Missions

The Laser-Enhanced Mission Communications Navigation and Operational Services (LEMNOS) office at Goddard Space Flight Center (GSFC) manages two NASA optical communication related projects, the Orion EM-2 Optical Communications Terminal (O2O) and the Integrated Laser Communications Relay Demonstration (LCRD) Low-Earth Orbit (LEO) User Modem and Amplifier Terminal (ILLUMA-T) projects. The main goal of LEMNOS is the advancement and implementation of optical communications systems and technologies for NASA missions. The O2O mission is sponsored by NASA's Human Exploration and Operations (HEO) Mission Directorate. The O2O project will provide optical communications capability to the Orion series of spacecraft, starting with the demonstration of operational utility on EM-2. It will be the first time a human exploration mission will rely on optical communications for its high-bandwidth link. ILLUMA-T is sponsored by the Space Communications and Navigation (SCaN) Program Office. It is destined for the International Space Station (ISS) as an external payload attached to the Japanese Experiment Module - Exposed Facility (JEM-EF). The ILLUMA-T project is developing an optical communications user terminal to demonstrate high bandwidth data transfer between LEO and the ground through the geosynchronous LCRD relay. ILLUMA-T will be the first demonstration of a LEO user of the LCRD system, pointing and tracking from a moving spacecraft at LEO to GEO satellite and vice versa, end-to-end operational utility of optical communications, and 51 Mbps forward link to ISS from ground. Both projects are collaborations between GSFC, Massachusetts Institute of Technology-Lincoln Laboratory (MIT-LL), and a number of contractors.

Laser Communications↗

NASA NTRS1989

Simulation and analysis of an intermediate frequency (IF) distribution system with applications for Space Station

Simulation and analysis results are described for a wideband fiber optic intermediate frequency distribution channel for a frequency division multiple access (FDMA) system where antenna equipment is remotely located from the signal processing equipment. The fiber optic distribution channel accommodates multiple signals received from a single antenna with differing power levels. Performance parameters addressed are intermodulation degradations, laser noise, and adjacent channel interference, as they impact the overall system design. Simulation results showed that the laser diode modulation level can be allowed to reach 100 percent without considerable degradation. The laser noise must be controlled as to provide a noise floor of less than -90 dBW/Hz. The fiber optic link increases the degradation due to power imbalance yet diminishes the effects of the transmit amplifier nonlinearity. Overall, optimal operation conditions can be found to yield a degradation level of about .1 dB caused by the fiber optic link.

Costello, Thomas A.↗

NASA NTRS1975

An optical radar for airborne use over natural waters

An optical radar for detecting targets in natural waters was built and tested in the Gulf of Mexico. The transmitter consists of a Q switched neodymium glass laser, with output amplified and doubled in KDP to 0.53 micrometer wavelength. The receiver incorporates a noval optical spatial filter to reduce the dynamic range required of the photodetector to a reasonable value. Detection of targets to a depth of 26 meters (84 feet) was achieved with a considerable sensitivity margin. The sensitivity of the radar is highly dependent on the optical attenuation coefficient. In general, measured returns fell between the values predicted on the basis of monopath and multipath attenuation. By means of simple physical arguments, a radar equation for the system was derived. To validate this theoretical model, measurements of optical attenuation and of water surface behavior were also instrumented, and some of these results are given.

Levis, C. A.↗

NASA NTRS2016

Study of Lateral Misalignment Tolerance of a Symmetric Free-Space Optical Link for Intra International Space Station Communication

This paper describes the study of lateral misalignment tolerance of a symmetric high-rate free-space optical link (FSOL) for use between International Space Station (ISS) payload sites and the main cabin. The link will enable gigabit per second (Gbps) transmission of data, which is up to three orders of magnitude greater than the current capabilities. This application includes 10-20 meter links and requires minimum size, weight, and power (SWaP). The optical power must not present an eye hazard and must be easily integrated into the existing ISS infrastructure. On the ISS, rapid thermal changes and astronaut movement will cause flexure of the structure which will potentially misalign the free space transmit and receive optics 9 cm laterally and 0.2 degrees angularly. If this misalignment is not accounted for, a loss of the link or degradation of link performance will occur. Power measurements were collected to better understand the effect of various system design parameters on lateral misalignment. Parameters that were varied include: the type of small form pluggable (SFP) transceivers, type of fiber, and transmitted power level. A potential solution was identified that can reach the lateral misalignment tolerance (decenter span) required to create an FSOL on the ISS by using 105 m core fibers, a duplex SFP, two channels of light, and two fiber amplifiers.

optical communications↗

NASA NTRS1985

Are some BL Lac objects artefacts of gravitational lensing?

It is proposed here that a significant fraction of BL Lac objects are optically violently variable quasars whose continuum emission has been greatly amplified, relative to the line emission, by pointlike gravitational lenses in intervening galaxies. Several anomalous physical and statistical properties of BL Lacs can be understood on the basis of this model, which is immediately testable on the basis of absorption line studies and by direct imaging.

Ostriker, J. P.↗

NASA NTRS2003

NASA Tech Briefs, November 2003

Topics covered include: Computer Program Recognizes Patterns in Time-Series Data; Program for User-Friendly Management of Input and Output Data Sets; Noncoherent Tracking of a Source of a Data-Modulated Signal; Software for Acquiring Image Data for PIV; Detecting Edges in Images by Use of Fuzzy Reasoning; A Timer for Synchronous Digital Systems; Prototype Parts of a Digital Beam-Forming Wide-Band Receiver; High-Voltage Droplet Dispenser; Network Extender for MIL-STD-1553 Bus; MMIC HEMT Power Amplifier for 140 to 170 GHz; Piezoelectric Diffraction-Based Optical Switches; Numerical Modeling of Nanoelectronic Devices; Organizing Diverse, Distributed Project Information; Eigensolver for a Sparse, Large Hermitian Matrix; Modified Polar-Format Software for Processing SAR Data; e-Stars Template Builder; Software for Acoustic Rendering; Functionally Graded Nanophase Beryllium/Carbon Composites; Thin Thermal-Insulation Blankets for Very High Temperatures; Prolonging Microgravity on Parabolic Airplane Flights; Device for Locking a Control Knob; Cable-Dispensing Cart; Foam Sensor Structures Would be Self-Deployable and Survive Hard Landings; Real-Gas Effects on Binary Mixing Layers; Earth-Space Link Attenuation Estimation via Ground Radar Kdp; Wedge Heat-Flux Indicators for Flash Thermography; Measuring Diffusion of Liquids by Common-Path Interferometry; Zero-Shear, Low-Disturbance Optical Delay Line; Whispering-Gallery Mode-Locked Lasers; Spatial Light Modulators as Optical Crossbar Switches; Update on EMD and Hilbert-Spectra Analysis of Time Series; Quad-Tree Visual-Calculus Analysis of Satellite Coverage; Dyakonov-Perel Effect on Spin Dephasing in n-Type GaAs; Update on Area Production in Mixing of Supercritical Fluids; and Quasi-Sun-Pointing of Spacecraft Using Radiation Pressure.

Source record↗

NASA NTRS2002

Fabry-Perot Interferometer-Based Electrooptic Modulator using LiNbO3 and Organic Thin Films

We report the study of a Fabry-Perot electro-optical modulator using thin crystalline film NPP, and Crystalline LiNbO3. We are able to observe 14, and 60 percent degree of modulation. Measurements were carried using a standard lock-in amplifier with a silicon detector. The proposal to design a Fabry-Perot electro-optic modulator with an intracavity electro-optically active organic material was based on the initial results using poled polymer thin films. The main feature of the proposed device is the observation that in traditional electrooptic modulators like a Packets cell, it requires few kilovolts of driving voltage to cause a 3 dB modulation even in high figure-of-merit electrooptic materials like LiNbO3. The driving voltage for the modulator can be reduced to as low as 10 volts by introducing the electrooptic material inside die resonant cavity of a Fabry-Perot modulator. This is because the transmission of the Fabry-Perot cavity varies nonlinearly with the change of refractive index or phase of light due to applied electric field.

Banks, C.↗

NASA NTRS1974

An autoranging scanning system and compatible methods of noise reduction

The autoranging scanning system discussed combines in a unique way four different methods for removing noise. The system employs a narrow-band amplifier. Other noise reduction methods make use of digital summation, convolution numbers, and the coaddition of scans. The system was designed to digitize the output of an infrared spectrometer and to record it on magnetic tape. Light passes through a mechanical light chopper and the spectrometer optics, and falls on the PbS cell to produce a signal which is amplified by the first preamplifier.

Saufley, D. C.↗

NASA NTRS2015

Recent Efforts in Advanced High Frequency Communications at the Glenn Research Center in Support of NASA Mission

This presentation will discuss research and technology development work at the NASA Glenn Research Center in advanced frequency communications in support of NASAs mission. An overview of the work conducted in-house and also in collaboration with academia, industry, and other government agencies (OGA) in areas such as antenna technology, power amplifiers, radio frequency (RF) wave propagation through Earths atmosphere, ultra-sensitive receivers, among others, will be presented. In addition, the role of these and other related RF technologies in enabling the NASA next generation space communications architecture will be also discussed.

Optical communications↗