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NASA NTRS1995

Optically-Switched Resonant Tunneling Diodes for Space-Based Optical Communication Applications

We are developing a new type of digital photo-receiver that has the potential to perform high speed optical-to-electronic conversion with a factor of 10 reduction in component count and power dissipation. In this paper, we describe the room-temperature photo-induced switching of this InP-based device which consists of an InGaAs/AlAs resonant tunneling diode integrated with an InGaAs absorber layer. When illuminated at an irradiance of greater than 5 Wcm(exp -2) using 1.3 micromillimeter radiation, the resonant tunneling diode switches from a high-conductance to a low-conductance electrical state and exhibits a voltage swing of up to 800 mV.

Moise, T. S.↗

NASA NTRS2001

Virtual Instrumentation for a Fiber-Optics-Based Artificial Nerve

A LabView-based computer interface for fiber-optic artificial nerves has been devised as a Masters thesis project. This project involves the use of outputs from wavelength multiplexed optical fiber sensors (artificial nerves), which are capable of producing dense optical data outputs for physical measurements. The potential advantages of using optical fiber sensors for sensory function restoration is the fact that well defined WDM-modulated signals can be transmitted to and from the sensing region allowing networked units to replace low-level nerve functions for persons desirous of "intelligent artificial limbs." Various FO sensors can be designed with high sensitivity and the ability to be interfaced with a wide range of devices including miniature shielded electrical conversion units. Our Virtual Instrument (VI) interface software package was developed using LabView's "Laboratory Virtual Instrument Engineering Workbench" package. The virtual instrument has been configured to arrange and encode the data to develop an intelligent response in the form of encoded digitized signal outputs. The architectural layout of our nervous system is such that different touch stimuli from different artificial fiber-optic nerve points correspond to gratings of a distinct resonant wavelength and physical location along the optical fiber. Thus, when an automated, tunable diode laser sends scans, the wavelength spectrum of the artificial nerve, it triggers responses that are encoded with different touch stimuli by way wavelength shifts in the reflected Bragg resonances. The reflected light is detected and a resulting analog signal is fed into ADC1 board and DAQ card. Finally, the software has been written such that the experimenter is able to set the response range during data acquisition.

Lyons, Donald R.↗

NASA NTRS2013

Optical Breath Gas Sensor for Extravehicular Activity Application

The function of the infrared gas transducer used during extravehicular activity in the current space suit is to measure and report the concentration of carbon dioxide (CO2) in the ventilation loop. The next generation portable life support system (PLSS) requires next generation CO2 sensing technology with performance beyond that presently in use on the Space Shuttle/International Space Station extravehicular mobility unit (EMU). Accommodation within space suits demands that optical sensors meet stringent size, weight, and power requirements. A laser diode spectrometer based on wavelength modulation spectroscopy is being developed for this purpose by Vista Photonics, Inc. Two prototype devices were delivered to NASA Johnson Space Center (JSC) in September 2011. The sensors incorporate a laser diode-based CO2 channel that also includes an incidental water vapor (humidity) measurement and a separate oxygen channel using a vertical cavity surface emitting laser. Both prototypes are controlled digitally with a field-programmable gate array/microcontroller architecture. The present development extends and upgrades the earlier hardware to the Advanced PLSS 2.0 test article being constructed and tested at JSC. Various improvements to the electronics and gas sampling are being advanced by this project. The combination of low power electronics with the performance of a long wavelength laser spectrometer enables multi-gas sensors with significantly increased performance over that presently offered in the EMU.

Wood, William R.↗

NASA NTRS2020

Polarization Sensing in Digital Holographic Microscopy

Digital holographic microscopy is well suited to the search for microbial species due in part to its intrinsic stability, volumetric imaging capability, and sensitivity to very dilute samples. This is all done with a system having no moving parts, making it additionally attractive for flight instrumentation. Our devices have been field tested on several occasions, and have demonstrated robustness to extreme conditions. When bacteria are alive and moving, they are easy to detect. However, some measurements are subtler. Can we distinguish between a live yet nonmotile species and a mineral, for instance? To provide another method of discrimination, we have added the ability to measure object polarization. This will allow us to characterize the sample by polarization state without any sacrifice in the spatial or temporal resolution (< 1um at 15 Hz). This snapshot polarization sensing is a new method for characterizing the sample under test. In this paper, we will describe the instrument design, the laboratory tests, and demonstrate its performance with live bacteria and crystalline samples.

Wallace, James↗

NASA NTRS2004

A Look from the Inside

NASA's Hubble Space Telescope has given the world amazing images of the distant stars, planets, and galaxies. The cutting-edge imaging technology that enhances the Hubble images also extends its benefits to life here on Earth, from deciphering previously unreadable portions of the Dead Sea Scrolls to improving digital mammographies for advanced cancer detection. This imaging technology is now helping physicians to perform micro-invasive arthroscopic surgery, which is the visual examination of an interior joint such as the knee. In 1997, NASA's Glenn Research Center signed a Space Act Agreement with Micro Medical Devices, Inc. (MMD), a medical device engineering company that licenses miniature surgical devices. At that time, MMD was in the process of developing a new micro-endoscope. This tool enables surgeons to view what is happening inside the body on a screen, eliminating the need for a more invasive diagnostic procedure. The images from the micro-endoscope needed to be extremely clear, a challenge with the tool s small size. The images also needed to be viewed in real time to allow surgeons to see what was happening in the body at that very moment. MMD established Clear Image Technology, LLC, of Elyria, Ohio, to commercialize the miniature endoscope. Clear Image Technology then partnered with Arthrotek, Inc., a sports medicine subsidiary of Biomet, Inc., to introduce the tool to the commercial market as the InnerVue[TM] Diagnostic Scope System. The InnerVue system is designed for use in a diagnostic environment, such as an office or outpatient service, to evaluate conditions within a joint. While the InnerVue scope is primarily being applied to the knee and shoulder, other small joints such as the wrist, elbow, and ankle are being investigated. A physician can use the system alone or in conjunction with magnetic resonance imaging (MRI) to determine the next treatment step for each patient. The procedure can be more accurate than MRI, particularly with diagnosing cartilage and articular surface damage and assessing arthritis severity.

Source record↗

NASA NTRS2009

Improved Scanners for Microscopic Hyperspectral Imaging

Improved scanners to be incorporated into hyperspectral microscope-based imaging systems have been invented. Heretofore, in microscopic imaging, including spectral imaging, it has been customary to either move the specimen relative to the optical assembly that includes the microscope or else move the entire assembly relative to the specimen. It becomes extremely difficult to control such scanning when submicron translation increments are required, because the high magnification of the microscope enlarges all movements in the specimen image on the focal plane. To overcome this difficulty, in a system based on this invention, no attempt would be made to move either the specimen or the optical assembly. Instead, an objective lens would be moved within the assembly so as to cause translation of the image at the focal plane: the effect would be equivalent to scanning in the focal plane. The upper part of the figure depicts a generic proposed microscope-based hyperspectral imaging system incorporating the invention. The optical assembly of this system would include an objective lens (normally, a microscope objective lens) and a charge-coupled-device (CCD) camera. The objective lens would be mounted on a servomotor-driven translation stage, which would be capable of moving the lens in precisely controlled increments, relative to the camera, parallel to the focal-plane scan axis. The output of the CCD camera would be digitized and fed to a frame grabber in a computer. The computer would store the frame-grabber output for subsequent viewing and/or processing of images. The computer would contain a position-control interface board, through which it would control the servomotor. There are several versions of the invention. An essential feature common to all versions is that the stationary optical subassembly containing the camera would also contain a spatial window, at the focal plane of the objective lens, that would pass only a selected portion of the image. In one version, the window would be a slit, the CCD would contain a one-dimensional array of pixels, and the objective lens would be moved along an axis perpendicular to the slit to spatially scan the image of the specimen in pushbroom fashion. The image built up by scanning in this case would be an ordinary (non-spectral) image. In another version, the optics of which are depicted in the lower part of the figure, the spatial window would be a slit, the CCD would contain a two-dimensional array of pixels, the slit image would be refocused onto the CCD by a relay-lens pair consisting of a collimating and a focusing lens, and a prism-gratingprism optical spectrometer would be placed between the collimating and focusing lenses. Consequently, the image on the CCD would be spatially resolved along the slit axis and spectrally resolved along the axis perpendicular to the slit. As in the first-mentioned version, the objective lens would be moved along an axis perpendicular to the slit to spatially scan the image of the specimen in pushbroom fashion.

Mao, Chengye↗

NASA NTRS2012

Optical Breath Gas Sensor for Extravehicular Activity Application

The function of the infrared gas transducer used during extravehicular activity (EVA) in the current space suit is to measure and report the concentration of carbon dioxide (CO2) in the ventilation loop. The next generation Portable Life Support System (PLSS) requires next generation CO2 sensing technology with performance beyond that presently in use on the Shuttle/International Space Station extravehicular mobility unit (EMU). Accommodation within space suits demands that optical sensors meet stringent size, weight, and power requirements. A laser diode (LD) spectrometer based on wavelength modulation spectroscopy (WMS) is being developed for this purpose by Vista Photonics, Inc. Two prototype devices were delivered to NASA Johnson Space Center (JSC) in September 2011. The sensors incorporate a laser diode based CO2 channel that also includes an incidental water vapor (humidity) measurement and a separate oxygen (O2) channel using a vertical cavity surface emitting laser (VCSEL). Both prototypes are controlled digitally with a field-programmable gate array (FPGA)/microcontroller architecture. Based on the results of the initial instrument development, further prototype development and testing of instruments leveraging the lessons learned were desired. The present development extends and upgrades the earlier hardware to the Advanced PLSS 2.0 test article being constructed and tested at JSC. Various improvements to the electronics and gas sampling are being advanced by this project. The combination of low power electronics with the performance of a long wavelength laser spectrometer enables multi-gas sensors with significantly increased performance over that presently offered in the EMU. .

Wood, William R.↗

NASA NTRS1975

Software for Digital Acquisition System and Application to Environmental Monitoring

Criteria for selection of a minicomputer for use as a core resident acquisition system were developed for the ODU Mobile Air Pollution Laboratory. A comprehensive data acquisition program named MONARCH was instituted in a DEC-8/E-8K 12-bit computer. Up to 32 analog voltage inputs are scanned sequentially, converted to BCD, and then to actual numbers. As many as 16 external devices (valves or any other two-state device) are controlled independently. MONARCH is written as a foreground-background program, controlled by an external clock which interrupts once per minute. Transducer voltages are averaged over user specified time intervals and, upon completion of any desired time sequence, outputted are: day, hour, minute, second; state of external valves; average value of each analogue voltage (E Format); as well as standard deviations of these values. Output is compatible with any serially addressed media.

Copeland, G. E.↗

NASA NTRS1990

Parallel asynchronous hardware implementation of image processing algorithms

Research is being carried out on hardware for a new approach to focal plane processing. The hardware involves silicon injection mode devices. These devices provide a natural basis for parallel asynchronous focal plane image preprocessing. The simplicity and novel properties of the devices would permit an independent analog processing channel to be dedicated to every pixel. A laminar architecture built from arrays of the devices would form a two-dimensional (2-D) array processor with a 2-D array of inputs located directly behind a focal plane detector array. A 2-D image data stream would propagate in neuron-like asynchronous pulse-coded form through the laminar processor. No multiplexing, digitization, or serial processing would occur in the preprocessing state. High performance is expected, based on pulse coding of input currents down to one picoampere with noise referred to input of about 10 femtoamperes. Linear pulse coding has been observed for input currents ranging up to seven orders of magnitude. Low power requirements suggest utility in space and in conjunction with very large arrays. Very low dark current and multispectral capability are possible because of hardware compatibility with the cryogenic environment of high performance detector arrays. The aforementioned hardware development effort is aimed at systems which would integrate image acquisition and image processing.

Coon, Darryl D.↗

NASA NTRS2009

Compact, Low-Overhead, MIL-STD-1553B Controller

A compact and flexible controller has been developed to provide MIL-STD- 1553B Remote Terminal (RT) communications and supporting and related functions with minimal demand on the resources of the system in which the controller is to be installed. (MIL-STD-1553B is a military standard that encompasses a method of communication and electrical-interface requirements for digital electronic subsystems connected to a data bus. MIL-STD-1553B is commonly used in defense and space applications.) Many other MIL-STD-1553B RT controllers are complicated, and to enable them to function, it is necessary to provide software and to use such ancillary separate hardware devices as microprocessors and dual-port memories. The present controller functions without need for software and any ancillary hardware. In addition, it contains a flexible system interface and extensive support hardware while including on-chip error-checking and diagnostic support circuitry. This controller is implemented within part of a modern field-programmable gate array.

Katz, Richard↗

NASA NTRS1972

Research study on stellar X-ray imaging experiment, volume 1

The use of microchannel plates as focal plane readout devices and the evaluation of mirrors for X-ray telescopes applied to stellar X-ray imaging is discussed. The microchannel plate outputs were either imaged on a phosphor screen which was viewed by a low light level vidicon or on a wire array which was read out by digitally processing the output of a charge division network attached to the wires. A service life test which was conducted on two image intensifiers is described.

Wilson, H. H.↗

NASA NTRS1984

Modernizing engine displays

The introduction of electronic fuel control to modern turbine engines has a number of advantages, which are related to an increase in engine performance and to a reduction or elimination of the problems associated with high angle of attack engine operation from the surface to 50,000 feet. If the appropriate engine display devices are available to the pilot, the fuel control system can provide a great amount of information. Some of the wealth of information available from modern fuel controls are discussed in this paper. The considered electronic engine control systems in their most recent forms are known as the Full Authority Digital Engine Control (FADEC) and the Digital Electronic Engine Control (DEEC). Attention is given to some details regarding the control systems, typical engine problems, the solution of problems with the aid of displays, engine displays in normal operation, an example display format, a multipage format, flight strategies, and hardware considerations.

Schneider, E. T.↗

NASA NTRS1988

Ka-band MMIC beam steered transmitter array

A 32 GHz six element linear transmitter array which employs MMIC phase shifters and power amplifiers is developed and its performance is evaluated. The MMIC phase shifters contains 14 MESFETs in three digital switched line and one analog loaded line phase shifter, and the MMIC power amplifiers are two stage amplifiers using GaAs MESFETs with 0.25 micron gate lengths and gate widths of 0.1 mm and 0.3 mm. The design of the array is described. The phase shift measurements for the MMIC devices are analyzed. The data reveal that the switched line phase shifters are accurate to within 7 pct; the power amplifier 1 dB compressed output power varied over 0.3 dB; the beamwidth of the array is 7.5 deg; and beam steering is over + or - 8 deg.

Riley, A. L.↗

NASA NTRS1993

MIRAGE: The data acquisition, analysis, and display system

Developed for the NASA Johnson Space Center and Life Sciences Directorate by GE Government Services, the Microcomputer Integrated Real-time Acquisition Ground Equipment (MIRAGE) system is a portable ground support system for Spacelab life sciences experiments. The MIRAGE system can acquire digital or analog data. Digital data may be NRZ-formatted telemetry packets of packets from a network interface. Analog signal are digitized and stored in experimental packet format. Data packets from any acquisition source are archived to a disk as they are received. Meta-parameters are generated from the data packet parameters by applying mathematical and logical operators. Parameters are displayed in text and graphical form or output to analog devices. Experiment data packets may be retransmitted through the network interface. Data stream definition, experiment parameter format, parameter displays, and other variables are configured using spreadsheet database. A database can be developed to support virtually any data packet format. The user interface provides menu- and icon-driven program control. The MIRAGE system can be integrated with other workstations to perform a variety of functions. The generic capabilities, adaptability and ease of use make the MIRAGE a cost-effective solution to many experimental data processing requirements.

Rosser, Robert S.↗

NASA NTRS1996

Evolving Requirements for Magnetic Tape Data Storage Systems

Magnetic tape data storage systems have evolved in an environment where the major applications have been back-up/restore, disaster recovery, and long term archive. Coincident with the rapidly improving price-performance of disk storage systems, the prime requirements for tape storage systems have remained: (1) low cost per MB, (2) a data rate balanced to the remaining system components. Little emphasis was given to configuring the technology components to optimize retrieval of the stored data. Emerging new applications such as network attached high speed memory (HSM), and digital libraries, place additional emphasis and requirements on the retrieval of the stored data. It is therefore desirable to consider the system to be defined both by STorage And Retrieval System (STARS) requirements. It is possible to provide comparative performance analysis of different STARS by incorporating parameters related to (1) device characteristics, and (2) application characteristics in combination with queuing theory analysis. Results of these analyses are presented here in the form of response time as a function of system configuration for two different types of devices and for a variety of applications.

Gniewek, John J.↗

NASA NTRS1999

Control of a Thrust Alignment Table for Modeling the Coning Dynamics of a Spinning Spacecraft with a Follower Force

This document presents a system controlling the motion of a spherical air bearing used in the modeling of spacecraft dynamics and controls in a laboratory environment. The system is part of the Spinning Rocket Simulator (SRS), used to simulate the coning of spacecraft during a thrusting stage. The reaction force at the spherical air bearing supporting the spacecraft model must coincide with the thrust axis of the model for proper simulation. Therefore, the bearing is translated in a circular path to introduce a centrifugal force. This horizontal force along with the gravitational reaction force at the bearing combines to simulate the direction of the spacecraft's thrust force. The control system receives attitude information from the spacecraft model via a laser beam embedded in the model that impinges on a photosensitive array. The non-linear system is controlled using high-speed lookup tables and digital techniques. A vector-controlled motor and a stepper motor are given the necessary signals to accurately control the turntable and platform supporting the air bearing. Preliminary performance data is presented. Mechanical elements of the table and platform are described in detail. A wireless (RF) data path for all devices on the spacecraft model to an off-table command computer is also described.

Halsmer, Dominic↗

NASA NTRS1999

Paint and Shoot

Through an initial SBIR contract with Langley Research Center, Stress Photonics, Inc. was able to successfully market their thermal strain measurement device, known as the Delta Therm 1000. The company was able to further its research on structural integrity analysis by signing another contract with Langley, this time a STTR contract, to develop its polariscope stress technology. Their commercial polariscope, the GFP 1000, involves a single rotating optical element and a digital camera for full-field image acquisition. The digital camera allows automated data to be acquired quickly and efficiently. Software analysis presents the data in an easy to interpret image format, depicting the magnitude of the shear strains and the directions of the principal strains.

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NASA NTRS1998

High Speed A/D DSP Interface for Carrier Doppler Tracking

As on-board satellite systems continue to increase in ability to perform self diagnostic checks, it will become more important for satellites to initiate ground communications contact. Currently, the NASA Space Network requires users to pre-arranged times for satellite communications links through the Tracking and Data Relay Satellite (TDRS). One of the challenges in implementing an on-demand access protocol into the Space Network, is the fact that a low Earth orbiting (LEO) satellite's communications will be subject to a doppler shift which is outside the capability of the NASA ground station to lock onto. In a prearranged system, the satellite's doppler is known a priori, and the ground station is able to lock onto the satellite's signal. This paper describes the development of a high speed analog to digital interface into a Digital Signal Processor (DSP). This system will be used for identifying the doppler shift of a LEO satellite through the Space Network, and aiding the ground station equipment in locking onto the signal. Although this interface is specific to one application, it can be used as a basis for interfacing other devices with a DSP.

Baggett, Timothy↗