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- Front Matter: Volume 8026
- Sensors in Transportation/Aerospace Applications
- Micro, Nano and Laser Photonics in Transportation
- Photonics In Harsh Environment, Signal Processing
- Environmental and Gas Monitoring
- Wirless Optical Link, Optical Satellite Communication
- Vision-Based and Imaging Sensors
Front Matter: Volume 8026
Front Matter: Volume 8026
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This PDF contains front matter associated with SPIE Proceedings Volume 8026, including Title Page, Copyright Information, Table of Contents, and the Conference Committee listing.
Sensors in Transportation/Aerospace Applications
POF hydrogen detection sensor systems for launch vehicles applications
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This paper describes the first successful Plastic Optical Fiber (POF) cable and glass fiber hydrogen detection
sensor systems developed for Delta IV Launch Vehicle. Hydrogen detection in space application is very
challenging; the hydrogen detection is priority for rocket industry and every transport device or any
application where hydrogen is involved. H2 sensors are necessary to monitor the detection possible leak to
avoid explosion, which can be highly dangerous. The hydrogen sensors had to perform in temperatures
between -18° C to 60° C (0° F to 140° F). The response of the sensor in this temperature regime was
characterized to ensure proper response of the sensors to fugitive hydrogen leakage during vehicle ground
operations. We developed the first 75 m combination of POF and glass fiber H2 sensors. Performed detail
investigation of POF-glass cables for attenuation loss, thermal, humidity, temperature, shock, accelerate
testing for life expectancy. Also evaluated absorption, operating and high/low temperatures, and harsh
environmental for glass-POF cables connectors. The same test procedures were performed for glass multi
mode fiber part of the H2 and O2 sensors. A new optical waveguides was designed and developed to
decrease the impact of both noise and long term drift of sensor. A field testing of sensors was performed at
NASA Stennis on the Aerospike X-33 to quantify the element of the sensor package that was responsible for
hydrogen detection and temperature.
Viability of guided-wave ultrasound diagnostics for sharply curved composite structures
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Guided wave ultrasound is well suited for inspection of laminate composite structures. Compared to nearly flat or gently
curved composites, performing accurate NDT on sharply curved structures is more complex with standard ultrasound
test methodologies, such as pulse-echo methods. Ultrasound propagation in curved composite structures is investigated
for sharply curved geometries. Responses are predicted based on dispersion models. Experimental results are presented
on 0.25 inch thick curved carbon fiber reinforced plastic (CFRP) composite geometry of an aircraft structural component
and compared with predicted values.
Advances towards the qualification of an aircraft fuel tank inert environment fiber optic oxygen sensor system
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An all optical pressure and temperature compensated fiber optic oxygen sensor (FOxSenseTM) system is
under qualification for use in the in-situ closed-loop-control of the inert atmosphere environment inside
fuel tanks of military and commercial aircraft. The all-optical oxygen environment control sensor is a
passive, intrinsically safe, fiber-optic sensor device with no electrical connections leading to the sensors
installed within the fuel tanks of an aircraft. To control the fuel tank environment, an array of multiple
sensors is deployed throughout the fuel tanks of an aircraft, and a remote multi-channel optoelectronic
system is used to monitor the status of all the sensors in real time to provide feedback oxygen
environment information to the on-board inert gas generating system (OBIGS). Qualification testing of
the all optical sensor have demonstrated the ability to monitor the oxygen environment inside a simulated
fuel tank environment in the oxygen range from 0% to 21% oxygen concentrations, temperatures from (-)
40°C to (+) 60°C, and altitudes from sea level to 40,000 feet. Fiber optic oxygen sensors with built-in
temperature compensation as well as the conduit fiber optic cables have passed DO-160E including
acoustic noise and burn test.
Intrinsically safe oxygen and hydrogen optical leak detector
Manal Beshay,
Simona Garon,
David Ruiz,
et al.
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Cryogenic leak detection is critical to space missions, particularly for avoiding launch delays. The real-time, multi-location,
early leak detection of oxygen and hydrogen down to ppm levels is extremely important for safety, reliability,
and economic reasons. One of the significant challenges in meeting these requirements has been the drift effect that is
caused by the exposure to extreme temperatures. This paper discusses the effect of the development of a sensor
supporting matrix to improve the overall behavior of oxygen and hydrogen optical sensors at cryogenic temperatures.
These achievements offer great advances in the fiber optic leak detection of cryogenic oxygen and hydrogen, specifically
for space applications. Emphasis on operational conditions such as -150 K and vacuum environments, in addition to
performance characteristics such as sensitivity (10 ppm) and response time (~ 3 sec), are addressed in this paper.
Micro, Nano and Laser Photonics in Transportation
Miniaturized real-time monitor for fuel cell leak applications
Manal Beshay,
Jai Ganesh Chandra Sekhar,
Jesús Delgado Alonso,
et al.
Show abstract
The intrinsically safe detection of hydrogen leaks in fuel cell vehicles (FCV) is critical for ensuring system operational
safety. An early indication of a leak will not only trigger an alarm in unsafe situations, but will also dramatically reduce
the risk and cost associated with fuel cell malfunction. This paper discusses the development of hydrogen leak detection
technology that is suitable for onboard, real-time, and intrinsically safe monitoring of fuel cells. This technique offers
FCV onboard sensing requirements with a sensitivity of 0.05% (500 ppm) in air, a response time of 3-5 seconds,
operation at 5-90%RH and 0-55°C, and power consumption ≤0.5 watts.
AUV-portable temperature-compensating fiber optic hydrophone
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Passive acoustic monitoring hydrophones with low power consumption for autonomous underwater vehicles (AUVs) are
desirable for long term unmanned monitoring of ocean acoustics including marine mammal acoustics as well as those
due to human activity. Fiber-optic hydrophones offer wider bandwidth and high sensitivity alternatives to conventional
piezoelectric transducer (PZT) devices. Deployment on board AUVs requires operation under a wide range of
temperature and pressure conditions that change with depth and location, hence, maintaining the sensitivity and
reliability over the operating range is crucial.
A read-out mechanism for a resonant hydrophone using a fiber Bragg grating (FBG) transducer is described. The read-out
uses a temperature tuned DFB laser diode to compensate for FBG changes with temperature and depth, enabling
operation over a wide temperature range. Its compact footprint and battery-powered readout system operation enables
portability on AUVs.
Linear polarizer local characterizations by polarimetric imaging for applications to polarimetric sensors for torque measurement for hybrid cars
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Usually manufacturer's specifications do not deal with the ability of linear sheet polarizers to have a
constant transmittance function over their geometric area. These parameters are fundamental for
developing low cost polarimetric sensors(for instance rotation, torque, displacement) specifically
for hybrid car (thermic + electricity power). It is then necessary to specially characterize
commercial polarizers sheets to find if they are adapted to this kind of applications.
In this paper, we present measuring methods and bench developed for this purpose, and some
preliminary characterization results. We state conclusions for effective applications to hybrid car
gearbox control and monitoring.
Photonics In Harsh Environment, Signal Processing
Incoherent light guide imager for harsh and complex environments
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Fiber optic imaging systems are used in many applications, including medical imaging, machinery diagnostics, and
remote sensing. Most commonly, coherent bundles of optical fibers are used that maintain the spatial positioning of
each fiber throughout the length of the bundle, resulting in a recognizable proximal (camera side) image that is almost
identical to the distal image projected into the bundle by the lens. Although coherent fiber bundles provide excellent
solutions for many imaging applications, their limited flexibility and thermal stress intolerance may prohibit them from
being used in harsh or complex environments. The flexibility and thermal tolerance of a fiber imaging system can be
significantly improved by using an incoherent bundle of fibers wherein the spatial positioning of each fiber is not
preserved throughout the length of the bundle. Incoherent bundles need to be calibrated to provide the means to
reconstruct distal imagery. In reported calibration schemes, the calibration time is strongly dependent on the ratio
between the bundle size and the fiber size. The calibration time can thus become prohibitive for highly resolved images
using many fibers. A novel calibration scheme is described for incoherent bundles where the calibration time is
proportional to the bundle-to-fiber size ratio, resulting in significantly reduced processing time and enabling more
highly resolved images. As an added benefit for medical and remote sensing applications, incoherent light guides
scramble the scene images, which may provide a desirable level of data privacy.
Digital micromirror device-based robust object boundary mapping sensor
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This paper presents a novel, non-intrusive, non-contact object boundary mapping sensor using a Digital Micromirror
Device (DMD) and real-time pixel processing. The presented sensor is ideal for use in environments where brightly
illuminated or radiating objects are in a hazardous environment such as in environments with radiation, heat, cold,
harmful machine parts, etc. Experimental results demonstrate the boundary mapping sensor for a rectangular target and a
multi-square target illuminated by visible wavelengths.
High resolution wide dynamic range distance sensor using spatial signal processing
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This paper presents a non-intrusive, non-contact object distance mapping sensor using an Electronically Controlled
Variable Focus Lens (ECVFL). The proposed sensor is a free-space-based optical sensor that uses ECVFL-based agile
optics to direct light from a object that requires terrain height mapping. The presented compact design makes the
proposed sensor ideal for use in environments where laser illuminated objects are in a hazardous environment such as in
environments with radiation, heat, cold, harmful machine parts, etc. The proposed design uses a few optical components
and smart detection optics for making its object distance/terrain measurements. The presented sensor can find potential
remote sensing applications in ground and space vehicle maneuvering, machine parts inspection and in chemical,
transportation and aerospace industries.
Multimode laser beam characterization using agile digital-analog photonics
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Presented is a novel design of a multimode laser beam analyzer to enable beam measurements of minimum beam waist
size, minimum waist location, divergence and the beam propagation parameter called M2. Experimental results
demonstrate these measurements for a 532 nm multimode test laser beam.
Evanescent wave absorption measurements of corroded materials using ATR and optical fibers
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The purpose of this research effort is to develop an in-situ corrosion sensing capability. The
technique will permit detection of corrosion on and within aircraft structures. This includes component
junctions that are susceptible to corrosion but which are not accessible for visual inspection. The prototype
experimental configuration we are developing includes long wave infrared transmitting optical fiber probes
interfaced with a Fourier Transform Infrared (FTIR) interferometer for evanescent wave absorption
spectroscopic measurements. The mature and fielded technique will allow periodic remote sensing for
detection of corrosion and for general onboard aircraft structural health monitoring. An experimental setup
using an Attenuated Total Reflection (ATR) crystal integrated with an FTIR spectrometer has been
assembled. Naturally occurring corrosion including Aluminum Hydroxide [Al(OH)3] is one of the main
corrosion products of aluminum the principle structural metal of aircraft. Absorption spectra of our model
corrosion product, pure Al(OH)3, have been collected with this ATR/FTIR experimental setup. The Al(OH)3spectra serve as reference spectral signatures. The spectra of corrosion samples from a simulated
corrosion process have been collected and compared with the reference Al(OH)3 spectra. Also absorption
spectra of naturally occurring corrosion collected from a fielded corroded aircraft part have been obtained
and compared with the spectra from the simulated corrosion.
Environmental and Gas Monitoring
Wireless/integrated strain monitoring and simulation system
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This paper addresses the development and real time test validation of an integrated hardware and
software environment that will be able to measure real-time in-situ strain and deformation fields
using a state-of-the-art wireless sensor system to enhance structural durability and damage
tolerance (D&DT), reliability via real-time structural health monitoring (SHM) for sensorized
aerospace structures. The tool will be a vital extension of existing suite of structural health
monitoring (SHM) and diagnostic prognostic system (DPS). The goal of the extended SHM-DPS is
to apply a multi-scale nonlinear physics-based finite element analyses (FEA) to the "as-is"
structural configuration to determine multi-site damage evolution, residual strength, remaining
service life, and future inspection intervals and procedures. Information from a distributed system
of wireless sensors will be used to determine the "as-is" state of the structure versus the
"as-designed" target. The approach enables active monitoring of aerospace structural component
performance and realization of DPS-based conditioned based maintenance. Software enhancements
will incorporate information from a sensor network system that is distributed over an aerospace
structural component. As case study DPS application a realistic composite stiffened panel
representative of fuselage/wing components is selected. Two stiffened panels is manufactured
and instrumented; a) embedded internally between composite layers, and b) surface mounted with
wireless sensors; the second of which with an optimized sensor network. The panels will be tested
in compression following low-velocity impact. The sensor system output will be routed and
integrated with a finite element analysis (FEA) tool to determine the panel's, multi-site damage
locations, and associated failure mechanisms, residual strength, remaining service life, and future
inspection interval. The FEA model utilizes the web/internet based GENOA progressive failure
analysis commercial software suite, durability and damage tolerance (D&DT), and reliability
software capable of evaluating both metallic and advanced composite structural panels under
service loading conditions. The approach utilizes a building block validation strategy, and
real-time structural health monitoring system.
All optical O2 sensors using innovative phase fluorimetry for monitoring of headspace in ullage for FAA mandated inerting fuel tanks of commercial airlines
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This paper explores the design and development of an all optical O2 sensor system that can be used for monitoring of
headspace gases in the ullage of inerting fuel tanks of commercial airplanes. Also included is detailed discussion of the
various test and measurement techniques used to estimate the O2 gas concentration .We compare the various intensity
based approaches and contrast them with the frequency domain techniques that measure phase to extract fluorescent
lifetimes. The various inerting fuel tank requirements are explained and finally a novel compact measurement system
using that uses the frequency heterodyning cross correlation technique that can be used for various applications is
described in detail while the benefits are explored together with some test data collected.
Battery outgassing sensor for electric drive vehicle energy storage systems
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Lithium-ion batteries have been proven efficient as high power density and low self-discharge rate energy storage
systems, specifically in electrical drive vehicles. An important safety factor associated with these systems is the potential
hazardous release and outgassing of toxic chemical vapors such as hydrogen fluoride (HF) and hydrogen sulfides (H2S),
and relatively elevated levels of carbon dioxide (CO2). The release and accumulation of such gases emphasizes an in-line
monitoring need. Intelligent Optical Systems, Inc. (IOS) has identified a viable approach for the development of an
onboard optical sensor array that can be used to monitor battery outgassing. This paper discusses the potential of
developing a battery outgas sensing approach that will meet sensitivity and response time requirements.
Wirless Optical Link, Optical Satellite Communication
High speed laser communication network for satellite systems
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Using optical links in space and building high speed laser communications network has proven to be an
extremely complicated task and many such schemes were tried without success in the past. However, in the
last few years, there has been impressive progress made to bring the concept to fruition in civilian and
government-non classified projects. In this paper we will focus on the requirements of the space-based
lasers and optics used for beam forming, as well as receiver antenna gain and detectors used in free space
communications. High data rate, small antenna size, narrow beam divergence, and a narrow field of view are
characteristics of laser communications that offer a number of potential advantages for system design.
Space-based optical communications using satellites in low earth orbit (LEO) and Geo-synchronous orbits
(GEO) hold great promise for the proposed Internet in the Sky network of the future. Also discussed are the
critical parameters in the transmitter, channel, receiver, and link budget that are employed in successful
inter-satellite communications system. We cover that Laser Communications offer a viable alternative to
established RF communications for inter-satellite links and other applications where high performance links
are a necessity.
Wireless optical links for avionics applications
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Recently there has been strong interest in wireless optical (WO) communication link applications in airplanes and
avionics platforms for size, weight, power, cost, and electromagnetic interference (EMI) reduction. Wireless optical
link has additional advantage of providing network security because the optical signal from wireless optical link is well
confined within an airplane or avionics vehicle. In this paper we discuss some potential wireless optical link
applications in commercial airplanes and the challenges in the implementation of wireless optical links for these
applications. We will present our experimental results on using white LED (WLED), visible laser source and free-space
small-form-factor (SFF) optical transceivers to demonstrate the viability of applying wireless optical links in avionics
platforms.
Towards development of a fiber optic-based transmission monitoring system
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There is interest in the rotorcraft community to develop health monitoring technologies. Among these technologies is
the ability to monitor the transmission planetary gear system. The gearbox environment does not lend itself to traditional
sensing technologies due to the harsh environment and crowed space. Traditional vibration-based diagnostics are based
on the output from externally mounted sensors, usually accelerometers fixed to the gearbox exterior. This type of system
relies on the ability of the vibration signal to travel from the gears through the gearbox housing. These sensors are also
susceptible to other interference including electrical magnetic interference (EMI). For these reasons, the development of
a fiber optic-based transmission monitoring system represents an appealing alternative to the accelerometer due to their
resistance to EMI and other signal corrupting influences. Aither Engineering has been working on integrating the fiber
optic sensors into the gearbox environment to measure strain on the ring gear of the planetary gear system. This
application utilizes a serial array of wavelength division multiplexed fiber Bragg grating (FBG) sensors. Work in this
area has been conducted at both the University of Maryland, College Park and more recently at the NASA Glenn
Research Center (NGRC) OH-58 transmission test rig facility. This paper discusses some of the testing results collected
from the fiber optic ring gear sensor array. Based on these results, recommendations for system requirements are
addressed in terms of the capabilities of the FBG instrumentation.
Review of optical fiber sensor technologies for hydrogen leak detection in hydrogen energy storage
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We introduce a review concerning hydrogen sensors already validated based on palladium, and we discuss the best
ways to proceed to achieve an ideal hydrogen sensor. We discuss the performances regarding the configuration
of an optical fiber hydrogen sensor as well as the used materials properties. We conclude that hydrogen sensors
using plasmonic effects are a seductive way to follow.
Vision-Based and Imaging Sensors
Speckle reduction technique for laser based automotive Head Up Display (HUD) projectors
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Recently various HUD (Head Up Display) projection engines have been introduced to industry, suited to solve the stringent
price/size/functionality constrains the automotive market. Some of the most promising projectors are laser based and project
directly a far-field image superimposed onto the driver's field of view by the mean of an optical combiner.
One of the major drawbacks of such technology is the parasitic speckle produced by the coherent nature of the illumination
(laser light), which has been proven to be very annoying and distracting for the driver. We propose a method to overcome the
parasitic speckle phenomenon in the HUD application, not by reducing it directly but rather by uniformizing the speckle
within the integration time of the eye, through generation of an orthogonal set of speckle modes for a single projected image.
Diffractive elements manufactured by grey tone mask and global laser lightning for transportation applications
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We report on a technology for multi-level microstructures manufacturing. Results are presented in the field
of multilevel diffractive optical elements (DOEs) fabrication. The DOEs presented as examples are Fresnel
lenses and Fourier computer generated holograms, calculated by means of a conventional Iterative Fourier
Transform Algorithm. The DOEs have a typical pixel dimension of 5x5 μm2 and are up to 512 by 512 pixels in
size.
The fabrication technique is based on polymer laser ablation through a chrome-on-quartz half-tone mask
with a demagnifying high NA lens. In our case, the mask is imaged onto the polymer with a 5x, 0.13 NA
reduction lens. The experimental results are presented and discussed.