The Nike Laser Facility and its Capabilities

NASA Astrophysics Data System (ADS)

Serlin, V.; Aglitskiy, Y.; Chan, L. Y.; Karasik, M.; Kehne, D. M.; Oh, J.; Obenschain, S. P.; Weaver, J. L.

2013-10-01

The Nike laser is a 56-beam krypton fluoride (KrF) system that provides 3 to 4 kJ of laser energy on target. The laser uses induced spatial incoherence to achieve highly uniform focal distributions. 44 beams are overlapped onto target with peak intensities up to 1016 W/cm2. The effective time-averaged illumination nonuniformity is < 0 . 2 %. Nike produces highly uniform ablation pressures on target allowing well-controlled experiments at pressures up to 20 Mbar. The other 12 laser beams are used to generate diagnostic x-rays radiographing the primary laser-illuminated target. The facility includes a front end that generates the desired temporal and spatial laser profiles, two electron-beam pumped KrF amplifiers, a computer-controlled optical system, and a vacuum target chamber for experiments. Nike is used to study the physics and technology issues of direct-drive laser fusion, such as, hydrodynamic and laser-plasma instabilities, studies of the response of materials to extreme pressures, and generation of X rays from laser-heated targets. Nike features a computer-controlled data acquisition system, high-speed, high-resolution x-ray and visible imaging systems, x-ray and visible spectrometers, and cryogenic target capability. Work supported by DOE/NNSA.

Synthesis and analysis of precise spaceborne laser ranging systems, volume 2. [Spacelab payload

NASA Technical Reports Server (NTRS)

Paddon, E. A.

1978-01-01

The performance capabilities of specific shuttle-based laser ranging systems were evaluated, and interface and support requirements were determined. The preliminary design of a shuttle-borne laser ranging experiment developed as part of the Spacelab program is discussed.

Verification of Wind Measurement to 450-Meter Altitude with Mobile Laser Doppler System

DOT National Transportation Integrated Search

1977-12-01

The Lockheed mobile atmospheric unit is a laser Doppler velocimeter system designed for the remote sensing of winds. The capability of the laser Doppler velocimeter accurately to measure winds to 150-meter altitude has been previously demonstrated. T...

Power transmission by laser beam from lunar-synchronous satellite

NASA Technical Reports Server (NTRS)

Williams, M. D.; Deyoung, R. J.; Schuster, G. L.; Choi, S. H.; Dagle, J. E.; Coomes, E. P.; Antoniak, Z. I.; Bamberger, J. A.; Bates, J. M.; Chiu, M. A.

1993-01-01

The possibility of beaming power from synchronous lunar orbits (the L1 and L2 Lagrange points) to a manned long-range lunar rover is addressed. The rover and two versions of a satellite system (one powered by a nuclear reactor, the other by photovoltaics) are described in terms of their masses, geometries, power needs, missions, and technological capabilities. Laser beam power is generated by a laser diode array in the satellite and converted to 30 kW of electrical power at the rover. Present technological capabilities, with some extrapolation to near future capabilities, are used in the descriptions. The advantages of the two satellite/rover systems over other such systems and over rovers with onboard power are discussed along with the possibility of enabling other missions.

U.S. Army High Energy Laser (HEL) technology program

NASA Astrophysics Data System (ADS)

Lavan, Michael J.; Wachs, John J.

2011-11-01

The US Army is investing in Solid State Laser (SSL) technology to assess counter rocket, artillery, and mortar (C-RAM) and counter unmanned aerial vehicle (C-UAV) capabilities of solid state based HEL systems, as well as other potential applications for HELs of interest to the Army. The Army HEL program thrust areas are systematically moving the technology forward toward weaponization, including solid state laser technologies, advances in beam control technology, and conducting major demonstrations. The High Energy Laser Mobile Demonstrator (HELMD) will be a major step toward demonstrating HEL weapon capability to the soldier. The US Army will continue to pursue technologies that enable more compact systems compatible with, for example, a Stryker tactical vehicle as a crucial part of our strategy to provide a capability to the warfighter that can maneuver with the force.

Solid-state coherent laser radar wind shear measuring systems

NASA Technical Reports Server (NTRS)

Huffaker, R. Milton

1992-01-01

Coherent Technologies, Inc. (CTI) was established in 1984 to engage in the development of coherent laser radar systems and subsystems with applications in atmospheric remote sensing, and in target tracking, ranging and imaging. CTI focuses its capabilities in three major areas: (1) theoretical performance and design of coherent laser radar system; (2) development of coherent laser radar systems for government agencies such as DoD and NASA; and (3) development of coherent laser radar systems for commercial markets. The topics addressed are: (1) 1.06 micron solid-state coherent laser radar system; (2) wind measurement using 1.06 micron system; and flashlamp-pumped 2.09 micron solid-state coherent laser radar system.

Three-dimensional laser microvision.

PubMed

Shimotahira, H; Iizuka, K; Chu, S C; Wah, C; Costen, F; Yoshikuni, Y

2001-04-10

A three-dimensional (3-D) optical imaging system offering high resolution in all three dimensions, requiring minimum manipulation and capable of real-time operation, is presented. The system derives its capabilities from use of the superstructure grating laser source in the implementation of a laser step frequency radar for depth information acquisition. A synthetic aperture radar technique was also used to further enhance its lateral resolution as well as extend the depth of focus. High-speed operation was made possible by a dual computer system consisting of a host and a remote microcomputer supported by a dual-channel Small Computer System Interface parallel data transfer system. The system is capable of operating near real time. The 3-D display of a tunneling diode, a microwave integrated circuit, and a see-through image taken by the system operating near real time are included. The depth resolution is 40 mum; lateral resolution with a synthetic aperture approach is a fraction of a micrometer and that without it is approximately 10 mum.

JPL self pulsed laser surface measurement system development. [large space deployed antenna structures

NASA Technical Reports Server (NTRS)

Berdahl, M.

1980-01-01

The use of a self pulsed laser system for accurately describing the surface shape of large space deployed antenna structures was evaluated. Tests with a breadboard system verified functional operation with short time resolution on the order of .2 mm, nonambiguous ranging, and a maximum range capability on the order of 150 m. The projected capability of the system is resolution of less than .1 mm over a reasonable time period and a range extension to over 300 m.

Control electronics for a multi-laser/multi-detector scanning system

NASA Technical Reports Server (NTRS)

Kennedy, W.

1980-01-01

The Mars Rover Laser Scanning system uses a precision laser pointing mechanism, a photodetector array, and the concept of triangulation to perform three dimensional scene analysis. The system is used for real time terrain sensing and vision. The Multi-Laser/Multi-Detector laser scanning system is controlled by a digital device called the ML/MD controller. A next generation laser scanning system, based on the Level 2 controller, is microprocessor based. The new controller capabilities far exceed those of the ML/MD device. The first draft circuit details and general software structure are presented.

The CSU Accelerator and FEL Facility

NASA Astrophysics Data System (ADS)

Biedron, Sandra; Milton, Stephen; D'Audney, Alex; Edelen, Jonathan; Einstein, Josh; Harris, John; Hall, Chris; Horovitz, Kahren; Martinez, Jorge; Morin, Auralee; Sipahi, Nihan; Sipahi, Taylan; Williams, Joel

2014-03-01

The Colorado State University (CSU) Accelerator Facility will include a 6-MeV L-Band electron linear accelerator (linac) with a free-electron laser (FEL) system capable of producing Terahertz (THz) radiation, a laser laboratory, a microwave test stand, and a magnetic test stand. The photocathode drive linac will be used in conjunction with a hybrid undulator capable of producing THz radiation. Details of the systems used in CSU Accelerator Facility are discussed.

Luminescent light source for laser pumping and laser system containing same

DOEpatents

Hamil, Roy A.; Ashley, Carol S.; Brinker, C. Jeffrey; Reed, Scott; Walko, Robert J.

1994-01-01

The invention relates to a pumping lamp for use with lasers comprising a porous substrate loaded with a component capable of emitting light upon interaction of the component with exciting radiation and a source of exciting radiation. Preferably, the pumping lamp comprises a source of exciting radiation, such as an electron beam, and an aerogel or xerogel substrate loaded with a component capable of interacting with the exciting radiation, e.g., a phosphor, to produce light, e.g., visible light, of a suitable band width and of a sufficient intensity to generate a laser beam from a laser material.

DAZZLE project: UAV to ground communication system using a laser and a modulated retro-reflector

NASA Astrophysics Data System (ADS)

Thueux, Yoann; Avlonitis, Nicholas; Erry, Gavin

2014-10-01

The advent of the Unmanned Aerial Vehicle (UAV) has generated the need for reduced size, weight and power (SWaP) requirements for communications systems with a high data rate, enhanced security and quality of service. This paper presents the current results of the DAZZLE project run by Airbus Group Innovations. The specifications, integration steps and initial performance of a UAV to ground communication system using a laser and a modulated retro-reflector are detailed. The laser operates at the wavelength of 1550nm and at power levels that keep it eye safe. It is directed using a FLIR pan and tilt unit driven by an image processing-based system that tracks the UAV in flight at a range of a few kilometers. The modulated retro-reflector is capable of a data rate of 20Mbps over short distances, using 200mW of electrical power. The communication system was tested at the Pershore Laser Range in July 2014. Video data from a flying Octocopter was successfully transmitted over 1200m. During the next phase of the DAZZLE project, the team will attempt to produce a modulated retro-reflector capable of 1Gbps in partnership with the research institute Acreo1 based in Sweden. A high speed laser beam steering capability based on a Spatial Light Modulator will also be added to the system to improve beam pointing accuracy.

Development of a Fiber Laser Welding Capability for the W76, MC4702 Firing Set

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samayoa, Jose

2010-05-12

Development work to implement a new welding system for a Firing Set is presented. The new system is significant because it represents the first use of fiber laser welding technology at the KCP. The work used Six-Sigma tools for weld characterization and to define process performance. Determinations of workable weld parameters and comparison to existing equipment were completed. Replication of existing waveforms was done utilizing an Arbitrary Pulse Generator (APG), which was used to modulate the fiber laser’s exclusive continuous wave (CW) output. Fiber laser weld process capability for a Firing Set is demonstrated.

Invited Article: Progress in coherent lithography using table-top extreme ultraviolet lasers

NASA Astrophysics Data System (ADS)

Li, W.; Urbanski, L.; Marconi, M. C.

2015-12-01

Compact (table top) lasers emitting at wavelengths below 50 nm had expanded the spectrum of applications in the extreme ultraviolet (EUV). Among them, the high-flux, highly coherent laser sources enabled lithographic approaches with distinctive characteristics. In this review, we will describe the implementation of a compact EUV lithography system capable of printing features with sub-50 nm resolution using Talbot imaging. This compact system is capable of producing consistent defect-free samples in a reliable and effective manner. Examples of different patterns and structures fabricated with this method will be presented.

Material Processing Laser Systems In Production

NASA Astrophysics Data System (ADS)

Taeusch, David R.

1988-11-01

The laser processing system is now a respected, productive machine tool in the manufacturing industries. Systems in use today are proving their cost effectiveness and capabilities of processing quality parts. Several types of industrial lasers are described and their applications are discussed, with emphasis being placed on the production environment and methods of protection required for optical equipment against this normally hostile environment.

Data collection and simulation of high range resolution laser radar for surface mine detection

NASA Astrophysics Data System (ADS)

Steinvall, Ove; Chevalier, Tomas; Larsson, Håkan

2006-05-01

Rapid and efficient detection of surface mines, IED's (Improvised Explosive Devices) and UXO (Unexploded Ordnance) is of high priority in military conflicts. High range resolution laser radars combined with passive hyper/multispectral sensors offer an interesting concept to help solving this problem. This paper reports on laser radar data collection of various surface mines in different types of terrain. In order to evaluate the capability of 3D imaging for detecting and classifying the objects of interest a scanning laser radar was used to scan mines and surrounding terrain with high angular and range resolution. These data were then fed into a laser radar model capable of generating range waveforms for a variety of system parameters and combinations of different targets and backgrounds. We can thus simulate a potential system by down sampling to relevant pixel sizes and laser/receiver characteristics. Data, simulations and examples will be presented.

Solar-pumped solid state Nd lasers

NASA Technical Reports Server (NTRS)

Williams, M. D.; Zapata, L.

1985-01-01

Solid state neodymium lasers are considered candidates for space-based polar-pumped laser for continuous power transmission. Laser performance for three different slab laser configurations has been computed to show the excellent power capability of such systems if heat problems can be solved. Ideas involving geometries and materials are offered as potential solutions to the heat problem.

Laser penetration spike welding: a welding tool enabling novel process and design opportunities

NASA Astrophysics Data System (ADS)

Dijken, Durandus K.; Hoving, Willem; De Hosson, J. Th. M.

2002-06-01

A novel method for laser welding for sheet metal. is presented. This laser spike welding method is capable of bridging large gaps between sheet metal plates. Novel constructions can be designed and manufactured. Examples are light weight metal epoxy multi-layers and constructions having additional strength with respect to rigidity and impact resistance. Its capability to bridge large gaps allows higher dimensional tolerances in production. The required laser systems are commercially available and are easily implemented in existing production lines. The lasers are highly reliable, the resulting spike welds are quickly realized and the cost price per weld is very low.

Inertial Navigation Sensors

DTIC Science & Technology

2010-03-01

Characterization Solutions Enabled by Laser Doppler Vibrometer Measurements, Proc. SPIE, Fifth International Conference on Vibration Measurements by Laser ...commercial capabilities: Ring Laser Gyros, Fiber Optic Gyros, and Micro-Electro-Mechanical Systems (MEMS) gyros and accelerometers. RLGs and FOGs are now...augmentation sensors have been tied into the inertial systems; e.g., GPS, velocity meters, seekers, star trackers, magnetometers, lidar , etc. The

Pulse generation and preamplification for long pulse beamlines of Orion laser facility.

PubMed

Hillier, David I; Winter, David N; Hopps, Nicholas W

2010-06-01

We describe the pulse generation, shaping, and preamplification system for the nanosecond beamlines of the Orion laser facility. The system generates shaped laser pulses of up to approximately 1 J of 100 ps-5 ns duration with a programmable temporal profile. The laser has a 30th-power supergaussian spatial profile and is diffraction limited. The system is capable of imposing 2D smoothing by spectral dispersion upon the beam, which will produce a nonuniformity of 10% rms at the target.

Target diagnostics for commissioning the AWE HELEN Laser Facility 100 TW chirped pulse amplification beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eagleton, R. T.; Clark, E. L.; Davies, H. M.

2006-10-15

The capability of the HELEN laser at the Atomic Weapons Establishment Aldermaston has been enhanced by the addition of a short-pulse laser beam to augment the twin opposing nanosecond time scale beams. The short-pulse beam utilizes the chirped pulse amplification (CPA) technique and is capable of delivering up to 60 J on target in a 500 fs pulse, around 100 TW, at the fundamental laser wavelength of 1.054 {mu}m. During the commissioning phase a number of diagnostic systems have been fielded, these include: x-ray pinhole imaging of the laser heated spot, charged particle time of flight, thermoluminescent dosimeter array, calibratedmore » radiochromic film, and CR39 nuclear track detector. These diagnostic systems have been used to verify the performance of the CPA beam to achieve a focused intensity of around 10{sup 19} W cm{sup -2} and to underwrite the facility radiological safety system.« less

Optical laser systems at the Linac Coherent Light Source

DOE PAGES

Minitti, Michael P.; Robinson, Joseph S.; Coffee, Ryan N.; ...

2015-04-22

Ultrafast optical lasers play an essential role in exploiting the unique capabilities of recently commissioned X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS). Pump–probe experimental techniques reveal ultrafast dynamics in atomic and molecular processes and reveal new insights in chemistry, biology, material science and high-energy-density physics. This manuscript describes the laser systems and experimental methods that enable cutting-edge optical laser/X-ray pump–probe experiments to be performed at LCLS.

Laser space communication experiment: Modulator technology

NASA Technical Reports Server (NTRS)

Goodwin, F. E.

1973-01-01

Results are presented of a contractual program to develop the modulator technology necessary for a 10.6 micron laser communication system using cadmium telluride as the modulator material. The program consisted of the following tasks: (1) The growth of cadmium telluride crystals of sufficient size and purity and with the necessary optical properties for use as laser modulator rods. (2) Develop a low loss antireflection coating for the cadmium telluride rods. (3) Design and build a modulator capable of 300 MHz modulation. (4) Develop a modulator driver capable of a data rate of 300 MBits/sec, 12 W rms output power, and 40 percent efficiency. (5) Assemble and test the modulator system. All design goals were met and the system was built and tested.

Comparative study of CW, nanosecond- and femtosecond-pulsed laser microcutting of AZ31 magnesium alloy stents.

PubMed

Gökhan Demir, Ali; Previtali, Barbara

2014-06-01

Magnesium alloys constitute an interesting solution for cardiovascular stents due to their biocompatibility and biodegradability in human body. Laser microcutting is the industrially accepted method for stent manufacturing. However, the laser-material interaction should be well investigated to control the quality characteristics of the microcutting process that concern the surface roughness, chemical composition, and microstructure of the final device. Despite the recent developments in industrial laser systems, a universal laser source that can be manipulated flexibly in terms of process parameters is far from reality. Therefore, comparative studies are required to demonstrate processing capabilities. In particular, the laser pulse duration is a key factor determining the processing regime. This work approaches the laser microcutting of AZ31 Mg alloy from the perspective of a comparative study to evaluate the machining capabilities in continuous wave (CW), ns- and fs-pulsed regimes. Three industrial grade machining systems were compared to reach a benchmark in machining quality, productivity, and ease of postprocessing. The results confirmed that moving toward the ultrashort pulse domain the machining quality increases, but the need for postprocessing remains. The real advantage of ultrashort pulsed machining was the ease in postprocessing and maintaining geometrical integrity of the stent mesh after chemical etching. Resultantly, the overall production cycle time was shortest for fs-pulsed laser system, despite the fact that CW laser system provided highest cutting speed.

Fiber laser-microscope system for femtosecond photodisruption of biological samples

PubMed Central

Yavaş, Seydi; Erdogan, Mutlu; Gürel, Kutan; Ilday, F. Ömer; Eldeniz, Y. Burak; Tazebay, Uygar H.

2012-01-01

We report on the development of a ultrafast fiber laser-microscope system for femtosecond photodisruption of biological targets. A mode-locked Yb-fiber laser oscillator generates few-nJ pulses at 32.7 MHz repetition rate, amplified up to ∼125 nJ at 1030 nm. Following dechirping in a grating compressor, ∼240 fs-long pulses are delivered to the sample through a diffraction-limited microscope, which allows real-time imaging and control. The laser can generate arbitrary pulse patterns, formed by two acousto-optic modulators (AOM) controlled by a custom-developed field-programmable gate array (FPGA) controller. This capability opens the route to fine optimization of the ablation processes and management of thermal effects. Sample position, exposure time and imaging are all computerized. The capability of the system to perform femtosecond photodisruption is demonstrated through experiments on tissue and individual cells. PMID:22435105

The 3D laser radar vision processor system

NASA Astrophysics Data System (ADS)

Sebok, T. M.

1990-10-01

Loral Defense Systems (LDS) developed a 3D Laser Radar Vision Processor system capable of detecting, classifying, and identifying small mobile targets as well as larger fixed targets using three dimensional laser radar imagery for use with a robotic type system. This processor system is designed to interface with the NASA Johnson Space Center in-house Extra Vehicular Activity (EVA) Retriever robot program and provide to it needed information so it can fetch and grasp targets in a space-type scenario.

The 3D laser radar vision processor system

NASA Technical Reports Server (NTRS)

Sebok, T. M.

1990-01-01

Loral Defense Systems (LDS) developed a 3D Laser Radar Vision Processor system capable of detecting, classifying, and identifying small mobile targets as well as larger fixed targets using three dimensional laser radar imagery for use with a robotic type system. This processor system is designed to interface with the NASA Johnson Space Center in-house Extra Vehicular Activity (EVA) Retriever robot program and provide to it needed information so it can fetch and grasp targets in a space-type scenario.

Laser Materials Processing Final Report CRADA No. TC-1526-98

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crane, J.; Lehane, C. J.

2017-09-08

This CRADA project was a joint effort between Lawrence Livermore National Laboratory (LLNL) and United Technologies Corporation (UTC)/Pratt & Whitney (P&W) to demonstrate process capability for drilling holes in turbine airfoils using LLNL-developed femtosecond laser machining technology. The basis for this development was the ability of femtosecond lasers to drill precision holes in variety of materials with little or no collateral damage. The ultimate objective was to develop a laser machine tool consisting of an extremely advanced femtosecond laser subsystem to be developed by LLNL on a best-effort basis and a drilling station for turbine blades and vanes to bemore » developed by P&W. In addition, P&W was responsible for commercializing the system. The goal of the so called Advanced Laser Drilling (ALD) system was to drill specified complex hole-shapes in turbine blades and vanes with a high degree precision and repeatability and simultaneously capable of very high speed processing.« less

A 10Gbps optical burst switching network incorporating ultra-fast (5ns) wavelength switched tunable laser sources

NASA Astrophysics Data System (ADS)

Ryan, Neil; Todd, Michael; Farrell, Tom; Lavin, Adrian; Rigole, Pierre-Jean; Corbett, Brian; Roycroft, Brendan; Engelstaedter, Jan-Peter

2017-11-01

This paper outlines the development of a prototype optical burst mode switching network based upon a star topology, the ultimate application of which could be as a transparent payload processor onboard satellite repeaters. The network architecture incorporates multiple tunable laser sources, burst mode receivers and a passive optical router (Arrayed Waveguide Grating). Each tunable optical signal should carry >=10Gbps and be capable of wavelength switching in c. 5ns timescales. Two monolithic tunable laser types, based upon different technologies, will be utilised: a Slotted Fabry Perot laser (a Fabry Perot laser with slots added in order to introduce controlled cavity perturbations); and a Modulated Grating Y-Branch Laser (MGY: a widely tunable, multi-section device similar to the DBR laser). While the Slotted Fabry Perot laser is expected to achieve the required switching times, it is an immature technology not yet capable of achieving tunability over 80 ITU channels from a single chip. The MGY device is a more mature technology and has full C-band ITU channel coverage, but is not capable of the required short switching times. Hence, in order to facilitate the integration of this more mature technology into the prototype breadboard with the requisite switching time capabilities, a system of `dual laser' transmitters is being developed to enable data transmission from one MGY laser while the other switches and vice-versa. This work is being performed under ESA contract AO 1-5025/06/NL/PM, Optical Technologies for Ultra - fast Processing.

Development of Shanghai satellite laser ranging station

NASA Technical Reports Server (NTRS)

Yang, Fu-Min; Tan, De-Tong; Xiao, Chi-Kun; Chen, Wan-Zhen; Zhang, J.-H.; Zhang, Z.-P.; Lu, Wen-Hu; Hu, Z.-Q.; Tang, W.-F.; Chen, J.-P.

1993-01-01

The topics covered include the following: improvement of the system hardware; upgrading of the software; the observation status; preliminary daylight tracking capability; testing the new type of laser; and future plans.

High-power direct-diode laser successes

NASA Astrophysics Data System (ADS)

Haake, John M.; Zediker, Mark S.

2004-06-01

Direct diode laser will become much more prevalent in the solar system of manufacturing due to their high efficiency, small portable size, unique beam profiles, and low ownership costs. There has been many novel applications described for high power direct diode laser [HPDDL] systems but few have been implemented in extreme production environments due to diode and diode system reliability. We discuss several novel applications in which the HPDDL have been implemented and proven reliable and cost-effective in production environments. These applications are laser hardening/surface modification, laser wire feed welding and laser paint stripping. Each of these applications uniquely tests the direct diode laser systems capabilities and confirms their reliability in production environments. A comparison of the advantages direct diode laser versus traditional industrial lasers such as CO2 and Nd:YAG and non-laser technologies such a RF induction, and MIG welders for each of these production applications is presented.

FALCON reactor-pumped laser description and program overview

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1989-12-01

The FALCON (Fission Activated Laser CONcept) reactor-pumped laser program at Sandia National Laboratories is examining the feasibility of high-power systems pumped directly by the energy from a nuclear reactor. In this concept we use the highly energetic fission fragments from neutron induced fission to excite a large volume laser medium. This technology has the potential to scale to extremely large optical power outputs in a primarily self-powered device. A laser system of this type could also be relatively compact and capable of long run times without refueling.

Simple method enabling pulse on command from high power, high frequency lasers

NASA Astrophysics Data System (ADS)

Baer, David J.; Marshall, Graham D.; Coutts, David W.; Mildren, Richard P.; Withford, Michael J.

2006-09-01

A method for addressing individual laser pulses in high repetition frequency systems using an intracavity optical chopper and novel electronic timing system is reported. This "pulse on command" capability is shown to enable free running and both subharmonic pulse rate and burst mode operation of a high power, high pulse frequency copper vapor laser while maintaining a fixed output pulse energy. We demonstrate that this technique can be used to improve feature finish when laser micromachining metal.

High-resolution imaging and target designation through clouds or smoke

DOEpatents

Perry, Michael D.

2003-01-01

A method and system of combining gated intensifiers and advances in solid-state, short-pulse laser technology, compact systems capable of producing high resolution (i.e., approximately less than 20 centimeters) optical images through a scattering medium such as dense clouds, fog, smoke, etc. may be achieved from air or ground based platforms. Laser target designation through a scattering medium is also enabled by utilizing a short pulse illumination laser and a relatively minor change to the detectors on laser guided munitions.

The Evolution of Air-Sea Battle: How Army Attack/Reconnaissance Aviation Fits into the Joint Concept for Access and Maneuver in the Global Commons

DTIC Science & Technology

2016-05-13

System (MTADS) has a day TV capability to laser designate and auto track tank-sized targets at 6,000 meters and a Forward Looking Infrared (FLIR...capability to laser designate and auto track tank-sized targets at 3,500 meters. The AH-64 D/E also possesses a Fire Control Radar (FCR) that allows it...a broad spectrum of size, capacity, duration, and security. At the low end are Forward Area Refueling Equipment ( FARE ) systems. These allow CH-47

Lens based adaptive optics scanning laser ophthalmoscope.

PubMed

Felberer, Franz; Kroisamer, Julia-Sophie; Hitzenberger, Christoph K; Pircher, Michael

2012-07-30

We present an alternative approach for an adaptive optics scanning laser ophthalmoscope (AO-SLO). In contrast to other commonly used AO-SLO instruments, the imaging optics consist of lenses. Images of the fovea region of 5 healthy volunteers are recorded. The system is capable to resolve human foveal cones in 3 out of 5 healthy volunteers. Additionally, we investigated the capability of the system to support larger scanning angles (up to 5°) on the retina. Finally, in order to demonstrate the performance of the instrument images of rod photoreceptors are presented.

Development of Laser, Detector, and Receiver Systems for an Atmospheric CO2 Lidar Profiling System

NASA Technical Reports Server (NTRS)

Ismail, Syed; Koch, Grady; Abedin, Nurul; Refaat, Tamer; Rubio, Manuel; Singh, Upendra

2008-01-01

A ground-based Differential Absorption Lidar (DIAL) is being developed with the capability to measure range-resolved and column amounts of atmospheric CO2. This system is also capable of providing high-resolution aerosol profiles and cloud distributions. It is being developed as part of the NASA Earth Science Technology Office s Instrument Incubator Program. This three year program involves the design, development, evaluation, and fielding of a ground-based CO2 profiling system. At the end of a three-year development this instrument is expected to be capable of making measurements in the lower troposphere and boundary layer where the sources and sinks of CO2 are located. It will be a valuable tool in the validation of NASA Orbiting Carbon Observatory (OCO) measurements of column CO2 and suitable for deployment in the North American Carbon Program (NACP) regional intensive field campaigns. The system can also be used as a test-bed for the evaluation of lidar technologies for space-application. This DIAL system leverages 2-micron laser technology developed under a number of NASA programs to develop new solid-state laser technology that provides high pulse energy, tunable, wavelength-stabilized, and double-pulsed lasers that are operable over pre-selected temperature insensitive strong CO2 absorption lines suitable for profiling of lower tropospheric CO2. It also incorporates new high quantum efficiency, high gain, and relatively low noise phototransistors, and a new receiver/signal processor system to achieve high precision DIAL measurements.

Development of a low-cost multiple diode PIV laser for high-speed flow visualization

NASA Astrophysics Data System (ADS)

Bhakta, Raj; Hargather, Michael

2017-11-01

Particle imaging velocimetry (PIV) is an optical visualization technique that typically incorporates a single high-powered laser to illuminate seeded particles in a fluid flow. Standard PIV lasers are extremely costly and have low frequencies that severely limit its capability in high speed, time-resolved imaging. The development of a multiple diode laser system consisting of continuous lasers allows for flexible high-speed imaging with a wider range of test parameters. The developed laser system was fabricated with off-the-shelf parts for approximately 500. A series of experimental tests were conducted to compare the laser apparatus to a standard Nd:YAG double-pulsed PIV laser. Steady and unsteady flows were processed to compare the two systems and validate the accuracy of the multiple laser design. PIV results indicate good correlation between the two laser systems and verifies the construction of a precise laser instrument. The key technical obstacle to this approach was laser calibration and positioning which will be discussed. HDTRA1-14-1-0070.

Evaluation of a satellite laser ranging technique using pseudonoise code modulated laser diodes

NASA Technical Reports Server (NTRS)

Ball, Carolyn Kay

1987-01-01

Several types of Satellite Laser Ranging systems exist, operating with pulsed, high-energy lasers. The distance between a ground point and an orbiting satellite can be determined to within a few centimeters. A new technique substitutes pseudonoise code modulated laser diodes, which are much more compact, reliable and less costly, for the lasers now used. Since laser diode technology is only now achieving sufficiently powerful lasers, the capabilities of the new technique are investigated. Also examined are the effects of using an avalanche photodiode detector instead of a photomultiplier tube. The influence of noise terms (including background radiation, detector dark and thermal noise and speckle) that limit the system range and performance is evaluated.

A novel robotic platform for laser-assisted transurethral surgery of the prostate.

PubMed

Russo, S; Dario, P; Menciassi, A

2015-02-01

Benign prostatic hyperplasia (BPH) is the most common pathology afflicting ageing men. The gold standard for the surgical treatment of BPH is transurethral resection of the prostate. The laser-assisted transurethral surgical treatment of BPH is recently emerging as a valid clinical alternative. Despite this, there are still some issues that hinder the outcome of laser surgery, e.g., distal dexterity is strongly reduced by the current endoscopic instrumentation and contact between laser and prostatic tissue cannot be monitored and optimized. This paper presents a novel robotic platform for laser-assisted transurethral surgery of BPH. The system, designed to be compatible with the traditional endoscopic instrumentation, is composed of a catheter-like robot provided with a fiber optic-based sensing system and a cable-driven actuation mechanism. The sensing system allows contact monitoring between the laser and the hypertrophic tissue. The actuation mechanism allows steering of the laser fiber inside the prostatic urethra of the patient, when contact must be reached. The design of the proposed robotic platform along with its preliminary testing and evaluation is presented in this paper. The actuation mechanism is tested in in vitro experiments to prove laser steering performances according to the clinical requirements. The sensing system is calibrated in experiments aimed to evaluate the capability of discriminating the contact forces, between the laser tip and the prostatic tissue, from the pulling forces exerted on the cables, during laser steering. These results have been validated demonstrating the robot's capability of detecting sub-Newton contact forces even in combination with actuation.

A Computer-Controlled Laser Bore Scanner

NASA Astrophysics Data System (ADS)

Cheng, Charles C.

1980-08-01

This paper describes the design and engineering of a laser scanning system for production applications. The laser scanning techniques, the timing control, the logic design of the pattern recognition subsystem, the digital computer servo control for the loading and un-loading of parts, and the laser probe rotation and its synchronization will be discussed. The laser inspection machine is designed to automatically inspect the surface of precision-bored holes, such as those in automobile master cylinders, without contacting the machined surface. Although the controls are relatively sophisticated, operation of the laser inspection machine is simple. A laser light beam from a commercially available gas laser, directed through a probe, scans the entire surface of the bore. Reflected light, picked up through optics by photoelectric sensors, generates signals that are fed to a mini-computer for processing. A pattern recognition techniques program in the computer determines acceptance or rejection of the part being inspected. The system's acceptance specifications are adjustable and are set to the user's established tolerances. However, the computer-controlled laser system is capable of defining from 10 to 75 rms surface finish, and voids or flaws from 0.0005 to 0.020 inch. Following the successful demonstration with an engineering prototype, the described laser machine has proved its capability to consistently ensure high-quality master brake cylinders. It thus provides a safety improvement for the automotive braking system. Flawless, smooth cylinder bores eliminate premature wearing of the rubber seals, resulting in a longer-lasting master brake cylinder and a safer and more reliable automobile. The results obtained from use of this system, which has been in operation about a year for replacement of a tedious, manual operation on one of the high-volume lines at the Bendix Hydraulics Division, have been very satisfactory.

Overview of the laser activities at Rheinmetall Waffe Munition

NASA Astrophysics Data System (ADS)

Ludewigt, Klaus; Riesbeck, Thomas; Schünemann, B.; Graf, A.; Jung, Markus; Schreiber, Th.; Eberhardt, Ramona; Tünnermann, A.

2012-11-01

The paper will give an overview over the laser weapon activities at RWM (Rheinmetall Waffe Munition) over the last years. Starting from the actual scenarios for laser weapon applications as: CRAM (Counter Rocket Artillery Mortar), Air Defence and UXO (unexploded ordnance) clearing. The basic requirements of a future laser weapon as beam diameter, beam quality, tracking capability, adaptive optics were deduced. For the UXO scenario a mobile directed energy laser demonstrator for humanitarian mine and UXO clearing based on fiber lasers is presented. Based on the parameters the system concept including the cooling system, power supply and the integration into the armoured vehicle TM 170 are explained. The contribution show first experiments of UXO and IED clearing. Different technical approaches to achieve laser power in the 100 kW regime combined with very good beam quality are discussed to fulfil the requirements of the CRAM and Air Defence scenario. Spectral coupling and the beam superimposing both are performed by Rheinmetall Waffe Munition. At the spectral coupling the basic technology parameters for the fiber laser and the dielectric grating as the latest results were put into context with the power levels reached at other groups. For the beam super imposing technology the basic experiments regarding the tracking capability and compensation of the atmosphere on the test range at Unterlüß will be explained. A generic 10 kW Laser Weapon Demonstrator based on 2 Laser Weapon Modules (LWM) from RWM each 5 kW fiber Laser with beam forming and tracking integrate by the team of RWM and RAD (Rheinmetall Air Defense) into a Ground based Air Defend system consisting of Skyguard and Millenium turret are presented. The flight path of the UAV within the valley of the life firing range at Ochsenboden Switzerland is shown. Selected results of the successful tests against UAV's are presented. It shows the capability of the generic 10 kW Laser Weapon Demonstrator to track and to destroy the target. From these results the next steps of Rheinmetall Waffe Munition for a 100 kW class laser weapon are explained.

Dual frequency comb metrology with one fiber laser

NASA Astrophysics Data System (ADS)

Zhao, Xin; Takeshi, Yasui; Zheng, Zheng

2016-11-01

Optical metrology techniques based on dual optical frequency combs have emerged as a hotly studied area targeting a wide range of applications from optical spectroscopy to microwave and terahertz frequency measurement. Generating two sets of high-quality comb lines with slightly different comb-tooth spacings with high mutual coherence and stability is the key to most of the dual-comb schemes. The complexity and costs of such laser sources and the associated control systems to lock the two frequency combs hinder the wider adoption of such techniques. Here we demonstrate a very simple and rather different approach to tackle such a challenge. By employing novel laser cavity designs in a mode-locked fiber laser, a simple fiber laser setup could emit dual-comb pulse output with high stability and good coherence between the pulse trains. Based on such lasers, comb-tooth-resolved dual-comb optical spectroscopy is demonstrated. Picometer spectral resolving capability could be realized with a fiber-optic setup and a low-cost data acquisition system and standard algorithms. Besides, the frequency of microwave signals over a large range can be determined based on a simple setup. Our results show the capability of such single-fiber-laser-based dual-comb scheme to reduce the complexity and cost of dual-comb systems with excellent quality for different dual-comb applications.

Spectral ophthalmoscopy based on supercontinuum

NASA Astrophysics Data System (ADS)

Cheng, Yueh-Hung; Yu, Jiun-Yann; Wu, Han-Hsuan; Huang, Bo-Jyun; Chu, Shi-Wei

2010-02-01

Confocal scanning laser ophthalmoscope (CSLO) has been established to be an important diagnostic tool for retinopathies like age-related macular degeneration, glaucoma and diabetes. Compared to a confocal laser scanning microscope, CSLO is also capable of providing optical sectioning on retina with the aid of a pinhole, but the microscope objective is replaced by the optics of eye. Since optical spectrum is the fingerprint of local chemical composition, it is attractive to incorporate spectral acquisition into CSLO. However, due to the limitation of laser bandwidth and chromatic/geometric aberration, the scanning systems in current CSLO are not compatible with spectral imaging. Here we demonstrate a spectral CSLO by combining a diffraction-limited broadband scanning system and a supercontinuum laser source. Both optical sectioning capability and sub-cellular resolution are demonstrated on zebrafish's retina. To our knowledge, it is also the first time that CSLO is applied onto the study of fish vision. The versatile spectral CSLO system will be useful to retinopathy diagnosis and neuroscience research.

High-rep-rate Thomson scattering for LHD

NASA Astrophysics Data System (ADS)

den Hartog, D. J.; Borchardt, M. T.; Holly, D. J.; Schmitz, O.; Yasuhara, R.; Yamada, I.; Funaba, H.; Osakabe, M.; Morisaki, T.

2017-10-01

A high-rep-rate pulse-burst laser system is being built for the LHD Thomson scattering (TS) diagnostic. This laser will have two operating scenarios, a fast-burst sequence of 15 kHz rep rate for at least 15 ms, and a slow-burst sequence of 1 kHz for at least 50 ms. There will be substantial flexibility in burst sequences for tailoring to experimental requirements. This new laser system will operate alongside the existing lasers in the LHD TS diagnostic, and will use the same beamline. This increase in temporal resolution capability complements the high spatial resolution (144 points) of the LHD TS diagnostic, providing unique measurement capability unmatched on any other fusion experiment. The new pulse-burst laser is a straightforward application of technology developed at UW-Madison, consisting of a Nd:YAG laser head with modular flashlamp drive units and a customized control system. Variable pulse-width drive of the flashlamps is accomplished by IGBT (insulated gate bipolar transistor) switching of electrolytic capacitor banks. Direct control of the laser Pockels cell drive enables optimal pulse energy extraction, producing >1.5 J q-switched pulses with 20 ns FWHM. Burst operation of this laser system will be used to capture fast time evolution of the electron temperature and density profiles during events such as ELMs, RMP perturbations, and various MHD modes. This work is supported by the U. S. Department of Energy and the National Institute for Fusion Science (Japan).

Laser rocket system analysis

NASA Technical Reports Server (NTRS)

Jones, W. S.; Forsyth, J. B.; Skratt, J. P.

1979-01-01

The laser rocket systems investigated in this study were for orbital transportation using space-based, ground-based and airborne laser transmitters. The propulsion unit of these systems utilizes a continuous wave (CW) laser beam focused into a thrust chamber which initiates a plasma in the hydrogen propellant, thus heating the propellant and providing thrust through a suitably designed nozzle and expansion skirt. The specific impulse is limited only by the ability to adequately cool the thruster and the amount of laser energy entering the engine. The results of the study showed that, with advanced technology, laser rocket systems with either a space- or ground-based laser transmitter could reduce the national budget allocated to space transportation by 10 to 345 billion dollars over a 10-year life cycle when compared to advanced chemical propulsion systems (LO2-LH2) of equal capability. The variation in savings depends upon the projected mission model.

Carbon Dioxide Laser Fiber Optics In Endoscopy

NASA Astrophysics Data System (ADS)

Fuller, Terry A.

1982-12-01

Carbon dioxide laser surgery has been limited to a great extent to surgical application on the integument and accessible cavities such as the cervix, vagina, oral cavities, etc. This limitation has been due to the rigid delivery systems available to all carbon dioxide lasers. Articulating arms (series of hollow tubes connected by articulating mirrors) have provided an effective means of delivery of laser energy to the patient as long as the lesion was within the direct line of sight. Even direct line-of-sight applications were restricted to physical dimension of the articulating arm or associated hand probes, manipulators and hollow tubes. The many attempts at providing straight endoscopic systems to the laser only stressed the need for a fiber optic capable of carrying the carbon dioxide laser wavelength. Rectangular and circular hollow metal waveguides, hollow dielectric waveguides have proven ineffective to the stringent requirements of a flexible surgical delivery system. One large diameter (1 cm) fiber optic delivery system, incorporates a toxic thalliumAbased fiber optic material. The device is an effective alternative to an articulating arm for external or conventional laser surgery, but is too large and stiff to use as a flexible endoscopic tool. The author describes the first highly flexible inexpensive series of fiber optic systems suitable for either conventional or endoscopic carbon dioxide laser surgery. One system (IRFLEX 3) has been manufactured by Medlase, Inc. for surgical uses capable of delivering 2000w, 100 mJ pulsed energy and 15w continuous wave. The system diameter is 0.035 inches in diameter. Surgically suitable fibers as small as 120 um have been manufactured. Other fibers (IRFLEX 142,447) have a variety of transmission characteristics, bend radii, etc.

Laser source for dimensional metrology: investigation of an iodine stabilized system based on narrow linewidth 633 nm DBR diode

NASA Astrophysics Data System (ADS)

Rerucha, Simon; Yacoot, Andrew; Pham, Tuan M.; Cizek, Martin; Hucl, Vaclav; Lazar, Josef; Cip, Ondrej

2017-04-01

We demonstrated that an iodine stabilized distributed Bragg reflector (DBR) diode based laser system lasing at a wavelength in close proximity to λ =633 nm could be used as an alternative laser source to the helium-neon lasers in both scientific and industrial metrology. This yields additional advantages besides the optical frequency stability and coherence: inherent traceability, wider optical frequency tuning range, higher output power and high frequency modulation capability. We experimentally investigated the characteristics of the laser source in two major steps: first using a wavelength meter referenced to a frequency comb controlled with a hydrogen maser and then on an interferometric optical bench testbed where we compared the performance of the laser system with that of a traditional frequency stabilized He-Ne laser. The results indicate that DBR diode laser system provides a good laser source for applications in dimensional (nano)metrology, especially in conjunction with novel interferometric detection methods exploiting high frequency modulation or multiaxis measurement systems.

All-femtosecond laser-assisted in situ keratomileusis

NASA Astrophysics Data System (ADS)

Gabryte, Egle; Danieliene, Egle; Vaiceliunaite, Agne; Ruksenas, Osvaldas; Vengris, Mikas; Danielius, Romualdas

2013-03-01

We present a femtosecond solid-state Yb:KGW laser system capable of performing the complete laser-assisted in situ keratomileusis (LASIK) ophthalmic procedure. The fundamental infrared radiation (IR) is used to create the corneal flap, and subsequently the corneal stromal ablation is performed using the ultraviolet (UV) pulses of the fifth harmonic. The heating of cornea, ablated surface quality, and healing outcomes of the surgeries performed using the femtosecond laser system are investigated by both ex vivo and in vivo experiments and compared to the results of conventional clinical ArF excimer laser application. The results of this research indicate the feasibility of clinical application of femtosecond UV lasers for LASIK procedure.

Laser-powered Martian rover

NASA Technical Reports Server (NTRS)

Harries, W. L.; Meador, W. E.; Miner, G. A.; Schuster, Gregory L.; Walker, G. H.; Williams, M. D.

1989-01-01

Two rover concepts were considered: an unpressurized skeleton vehicle having available 4.5 kW of electrical power and limited to a range of about 10 km from a temporary Martian base and a much larger surface exploration vehicle (SEV) operating on a maximum 75-kW power level and essentially unrestricted in range or mission. The only baseline reference system was a battery-operated skeleton vehicle with very limited mission capability and range and which would repeatedly return to its temporary base for battery recharging. It was quickly concluded that laser powering would be an uneconomical overkill for this concept. The SEV, on the other hand, is a new rover concept that is especially suited for powering by orbiting solar or electrically pumped lasers. Such vehicles are visualized as mobile habitats with full life-support systems onboard, having unlimited range over the Martian surface, and having extensive mission capability (e.g., core drilling and sampling, construction of shelters for protection from solar flares and dust storms, etc.). Laser power beaming to SEV's was shown to have the following advantages: (1) continuous energy supply by three orbiting lasers at 2000 km (no storage requirements as during Martian night with direct solar powering); (2) long-term supply without replacement; (3) very high power available (MW level possible); and (4) greatly enhanced mission enabling capability beyond anything currently conceived.

Laser-powered Martian rover

NASA Astrophysics Data System (ADS)

Harries, W. L.; Meador, W. E.; Miner, G. A.; Schuster, Gregory L.; Walker, G. H.; Williams, M. D.

1989-07-01

Two rover concepts were considered: an unpressurized skeleton vehicle having available 4.5 kW of electrical power and limited to a range of about 10 km from a temporary Martian base and a much larger surface exploration vehicle (SEV) operating on a maximum 75-kW power level and essentially unrestricted in range or mission. The only baseline reference system was a battery-operated skeleton vehicle with very limited mission capability and range and which would repeatedly return to its temporary base for battery recharging. It was quickly concluded that laser powering would be an uneconomical overkill for this concept. The SEV, on the other hand, is a new rover concept that is especially suited for powering by orbiting solar or electrically pumped lasers. Such vehicles are visualized as mobile habitats with full life-support systems onboard, having unlimited range over the Martian surface, and having extensive mission capability (e.g., core drilling and sampling, construction of shelters for protection from solar flares and dust storms, etc.). Laser power beaming to SEV's was shown to have the following advantages: (1) continuous energy supply by three orbiting lasers at 2000 km (no storage requirements as during Martian night with direct solar powering); (2) long-term supply without replacement; (3) very high power available (MW level possible); and (4) greatly enhanced mission enabling capability beyond anything currently conceived.

Nike Facility Diagnostics and Data Acquisition System

NASA Astrophysics Data System (ADS)

Chan, Yung; Aglitskiy, Yefim; Karasik, Max; Kehne, David; Obenschain, Steve; Oh, Jaechul; Serlin, Victor; Weaver, Jim

2013-10-01

The Nike laser-target facility is a 56-beam krypton fluoride system that can deliver 2 to 3 kJ of laser energy at 248 nm onto targets inside a two meter diameter vacuum chamber. Nike is used to study physics and technology issues related to laser direct-drive ICF fusion, including hydrodynamic and laser-plasma instabilities, material behavior at extreme pressures, and optical and x-ray diagnostics for laser-heated targets. A suite of laser and target diagnostics are fielded on the Nike facility, including high-speed, high-resolution x-ray and visible imaging cameras, spectrometers and photo-detectors. A centrally-controlled, distributed computerized data acquisition system provides robust data management and near real-time analysis feedback capability during target shots. Work supported by DOE/NNSA.

High Average Power Raman Conversion in Diamond: ’Eyesafe’ Output and Fiber Laser Conversion

DTIC Science & Technology

2015-06-19

Eyesafe’ output and fiber laser conversion 5a. CONTRACT NUMBER FA2386-12-1-4055 5b. GRANT NUMBER Grant 12RSZ077_124055 5c. PROGRAM ELEMENT...generating 380 W was demonstrated using a 630 W Ybdoped fiber laser system. In each case the performance was unsaturated and limited by the available pump...converter for conventional high power laser technologies including Nd doped lasers and Yb-doped fiber lasers. Diamond’s power handling capability now

Advances in High Energy Solid-State 2-micron Laser Transmitter Development for Ground and Airborne Wind and CO2 Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Chen, Songsheng; Kavaya, Michael J.; Trieu, Bo; Bai, Yingxin; Petzar, Paul; Modlin, Edward A.; Koch, Grady;

Progress on High-Energy 2-micron Solid State Laser for NASA Space-Based Wind and Carbon Dioxide Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.

2011-01-01

Sustained research efforts at NASA Langley Research Center during last fifteen years have resulted in significant advancement of a 2-micron diode-pumped, solid-state laser transmitter for wind and carbon dioxide measurements from ground, air and space-borne platforms. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar system for measuring atmospheric CO2 concentration profiles. Researchers at NASA Langley Research Center have developed a compact, flight capable, high energy, injection seeded, 2-micron laser transmitter for ground and airborne wind and carbon dioxide measurements. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser transmitter was integrated into a mobile trailer based coherent Doppler wind and CO2 DIAL system and was deployed during field measurement campaigns. This paper will give an overview of 2-micron solid-state laser technology development and discuss results from recent ground-based field measurements.

Bringing PW-class lasers to XFELs (Conference Presentation)

NASA Astrophysics Data System (ADS)

Tomizawa, Hiromitsu

2017-06-01

Experimental researches using high power optical lasers combined with free electron lasers (FELs) open new frontiers in high energy density (HED) sciences. Probing and pumping capabilities are dramatically improved due to the brightness of the XFEL pulses with ultrafast duration. Besides, the peak intensities of Ti:sapphire laser Chirped Pulse Amplification (CPA) systems reach petawatt (PW)-class with operating in few tens of fs and commercially available at a few Hz of repetition rate. We have been developing an experimental platform for HED sciences using high power, high intensity optical lasers at the XFEL facility, SACLA.Currently, an experimental platform with a dual 0.5 PW Ti:Sapphire laser system is under beam commissioning for experiments combined with the SACLA's x-ray beam for research objectives that require more peak power in the optical laser pulses with a few tens of fs. The optical laser system is designed to deliver two laser beams simultaneously with the maximum power of 0.5 PW in each into a target chamber located in an experimental hutch 6 (EH6) at BL2, which was recently commissioned as a SACLA's 2nd hard x-ray beamline. A focusing capability using sets of compound refractive lenses will be applied to increase the x-ray fluence on the target sample. One of the most key issues for the integrated experimental platform is development of diagnostics that meets requirements both from the high power laser (e.g. resistance to harsh environments) and from the XFEL (e.g. adaptation to the available data acquisition system). The status and future perspective of the development including automatic laser alignment systems will be reported in the presentation. We will discuss the most promising and important new physics experiments that will be enabled by the combination of PW-class lasers and the world-class FEL's x-ray beam.

A review of the development of optical countermeasures

NASA Astrophysics Data System (ADS)

Titterton, David H.

2004-12-01

Optical countermeasures have been used for several millenia to provide a defensive capability capability. The fundamental approach is to use an intense optical source to dazzle a sensor or distract an operator or target tracking system causing a weapon to miss its intended target. The development of the laser has provided a stimulus for anumber of soft-kill weapon systems used to enhance platform survivability and anti-air missile applications; in this case the laser may cause dazzle, or if the beam is sufficiently intense it may cause damage. Laser technology is also crucial for an aspect of directed energy weapons. The various aspects of optical countermeasures are considered in this paper, including defeat mechanisms of active and passive techniques. The review includes a historical perspective through to prospects for the future.

Experimental evaluation of penetration capabilities of a Geiger-mode APD array laser radar system

NASA Astrophysics Data System (ADS)

Jonsson, Per; Tulldahl, Michael; Hedborg, Julia; Henriksson, Markus; Sjöqvist, Lars

2017-10-01

Laser radar 3D imaging has the potential to improve target recognition in many scenarios. One case that is challenging for most optical sensors is to recognize targets hidden in vegetation or behind camouflage. The range resolution of timeof- flight 3D sensors allows segmentation of obscuration and target if the surfaces are separated far enough so that they can be resolved as two distances. Systems based on time-correlated single-photon counting (TCSPC) have the potential to resolve surfaces closer to each other compared to laser radar systems based on proportional mode detection technologies and is therefore especially interesting. Photon counting detection is commonly performed with Geigermode Avalanche Photodiodes (GmAPD) that have the disadvantage that they can only detect one photon per laser pulse per pixel. A strong return from an obscuring object may saturate the detector and thus limit the possibility to detect the hidden target even if photons from the target reach the detector. The operational range where good foliage penetration is observed is therefore relatively narrow for GmAPD systems. In this paper we investigate the penetration capability through semi-transparent surfaces for a laser radar with a 128×32 pixel GmAPD array and a 1542 nm wavelength laser operating at a pulse repetition frequency of 90 kHz. In the evaluation a screen was placed behind different canvases with varying transmissions and the detected signals from the surfaces for different laser intensities were measured. The maximum return from the second surface occurs when the total detection probability is around 0.65-0.75 per pulse. At higher laser excitation power the signal from the second surface decreases. To optimize the foliage penetration capability it is thus necessary to adaptively control the laser power to keep the returned signal within this region. In addition to the experimental results, simulations to study the influence of the pulse energy on penetration through foliage in a scene with targets behind vegetation are presented. The optimum detection of targets occurs here at a slightly higher total photon count rate probability because a number of pixel have no obscuration in front the target in their field of view.

Diode laser satellite systems for beamed power transmission

NASA Technical Reports Server (NTRS)

Williams, M. D.; Kwon, J. H.; Walker, G. H.; Humes, D. H.

1990-01-01

A power system composed of an orbiting laser satellite and a surface-based receiver/converter is described. Power is transmitted from the satellite to the receiver/converter by laser beam. The satellite components are: (1) solar collector; (2) blackbody; (3) photovoltaic cells; (4) heat radiators; (5) laser system; and (6) transmission optics. The receiver/converter components are: receiver dish; lenticular lens; photocells; and heat radiator. Although the system can be adapted to missions at many locations in the solar system, only two are examined here: powering a lunar habitat; and powering a lunar rover. Power system components are described and their masses, dimensions, operating powers, and temperatures, are estimated using known or feasible component capabilities. The critical technologies involved are discussed and other potential missions are mentioned.

OH Planar Laser Induced Fluorescence (PLIF) Measurements for the Study of High Pressure Flames: An Evaluation of a New Laser and a New Camera System

NASA Technical Reports Server (NTRS)

Tedder, Sarah; Hicks, Yolanda

2012-01-01

Planar laser induced fluorescence (PLIF) is used by the Combustion Branch at the NASA Glenn Research Center (NASA Glenn) to assess the characteristics of the flowfield produced by aircraft fuel injectors. To improve and expand the capabilities of the PLIF system new equipment was installed. The new capabilities of the modified PLIF system are assessed by collecting OH PLIF in a methane/air flame produced by a flat flame burner. Specifically, the modifications characterized are the addition of an injection seeder to a Nd:YAG laser pumping an optical parametric oscillator (OPO) and the use of a new camera with an interline CCD. OH fluorescence results using the injection seeded OPO laser are compared to results using a Nd:YAG pumped dye laser with ultraviolet extender (UVX). Best settings of the new camera for maximum detection of PLIF signal are reported for the controller gain and microchannel plate (MCP) bracket pulsing. Results are also reported from tests of the Dual Image Feature (DIF) mode of the new camera which allows image pairs to be acquired in rapid succession. This allows acquisition of a PLIF image and a background signal almost simultaneously. Saturation effects in the new camera were also investigated and are reported.

Damage Thresholds for Exposure to NIR and Blue Lasers in an In Vitro RPE Cell System

DTIC Science & Technology

2006-07-01

damage , and to identify antioxidants capable of protecting these cells from laser-in- duced cell death. MATERIALS AND METHODS The human RPE cell...melanosomes in blue laser-induced damage in vitro, which confirms the view that melanin plays an important role in photochemical damage mechanisms in...community has only a validating role in the animal ED50 damage threshold data used by safety committees. Systems of in vitro analysis must be

Investigation of Plasma Surface Interactions with the PISCES ELM Laser System

NASA Astrophysics Data System (ADS)

Umstadter, K. R.; Baldwin, M.; Hanna, J.; Doerner, R.; Lynch, T.; Palmer, T.; Tynan, G. R.

2007-11-01

When an ELM occurs in tokamaks, up to 30% of the pedestal energy can be deposited on the wall of the tokamak causing heating & material loss due to sublimation, evaporation and melt splashing of plasma facing components (PFCs) and expansion of the ejected material into the plasma. We have explored heat pulses using an electrical power circuit to draw electrons from the plasma to heat samples ohmically. This system is limited in power to ˜250kJ/m^2 at the minimum pulse width of 10ms and depletes the plasma column, complicating spectroscopy. We have completed calculations that indicate that a pulsed laser system can be used to simulate the heat pulse of ELMs. We are integrating laser systems into the existing PFC research program in PISCES, a laboratory facility capable of reproducing plasma-materials interactions expected during normal operation of large tokamaks. Two Nd:YAG lasers capable of delivering up to 50J of energy over various pulsewidths are used for the experiments. Laser heat pulse only, H+/D+ plasma only, and laser+plasma experiments were conducted and initial results indicate that metals behave very differently while exposed to plasma and simultaneous heat pulses. We will also discuss initial results for carbon PFCs and material transport into the plasma. Supported by US DoE grant DE-FG02-07ER-54912.

Attacking the information access problem with expert systems

NASA Technical Reports Server (NTRS)

Ragusa, James M.; Orwig, Gary W.

1991-01-01

The results of applications research directed at finding an improved method of storing and accessing information are presented. Twelve microcomputer-based expert systems shells and five laser-optical formats have been studied, and the general and specific methods of interfacing these technologies are being tested in prototype systems. Shell features and interfacing capabilities are discussed, and results from the study of five laser-optical formats are recounted including the video laser, compact, and WORM disks, and laser cards and film. Interfacing, including laser disk device driver interfacing, is discussed and it is pointed out that in order to control the laser device from within the expert systems application, the expert systems shell must be able to access the device driver software. Potential integrated applications are investigated and an initial list is provided including consumer services, travel, law enforcement, human resources, marketing, and education and training.

A vision-based system for fast and accurate laser scanning in robot-assisted phonomicrosurgery.

PubMed

Dagnino, Giulio; Mattos, Leonardo S; Caldwell, Darwin G

2015-02-01

Surgical quality in phonomicrosurgery can be improved by open-loop laser control (e.g., high-speed scanning capabilities) with a robust and accurate closed-loop visual servoing systems. A new vision-based system for laser scanning control during robot-assisted phonomicrosurgery was developed and tested. Laser scanning was accomplished with a dual control strategy, which adds a vision-based trajectory correction phase to a fast open-loop laser controller. The system is designed to eliminate open-loop aiming errors caused by system calibration limitations and by the unpredictable topology of real targets. Evaluation of the new system was performed using CO(2) laser cutting trials on artificial targets and ex-vivo tissue. This system produced accuracy values corresponding to pixel resolution even when smoke created by the laser-target interaction clutters the camera view. In realistic test scenarios, trajectory following RMS errors were reduced by almost 80 % with respect to open-loop system performances, reaching mean error values around 30 μ m and maximum observed errors in the order of 60 μ m. A new vision-based laser microsurgical control system was shown to be effective and promising with significant positive potential impact on the safety and quality of laser microsurgeries.

Test techniques for determining laser ranging system performance

NASA Technical Reports Server (NTRS)

Zagwodzki, T. W.

1981-01-01

Procedures and results of an on going test program intended to evaluate laser ranging system performance levels in the field as well as in the laboratory are summarized. Tests show that laser ranging system design requires consideration of time biases and RMS jitters of individual system components. All simple Q switched lasers tested were found to be inadequate for 10 centimeter ranging systems. Timing discriminators operating over a typical 100:1 dynamic signal range may introduce as much as 7 to 9 centimeters of range bias. Time interval units commercially available today are capable of half centimeter performance and are adequate for all field systems currently deployed. Photomultipliers tested show typical tube time biases of one centimeter with single photoelectron transit time jitter of approximately 10 centimeters. Test results demonstrate that NASA's Mobile Laser Ranging System (MOBLAS) receiver configuration is limiting system performance below the 100 photoelectron level.

Laser Technology in Interplanetary Exploration: The Past and the Future

NASA Technical Reports Server (NTRS)

Smith, David E.

2000-01-01

Laser technology has been used in planetary exploration for many years but it has only been in the last decade that laser altimeters and ranging systems have been selected as flight instruments alongside cameras, spectrometers, magnetometers, etc. Today we have an active laser system operating at Mars and another destined for the asteroid Eros. A few years ago a laser ranging system on the Clementine mission changed much of our thinking about the moon and in a few years laser altimeters will be on their way to Mercury, and also to Europa. Along with the increased capabilities and reliability of laser systems has came the realization that precision ranging to the surface of planetary bodies from orbiting spacecraft enables more scientific problems to be addressed, including many associated with planetary rotation, librations, and tides. In addition, new Earth-based laser ranging systems working with similar systems on other planetary bodies in an asynchronous transponder mode will be able to make interplanetary ranging measurements at the few cm level and will advance our understanding of solar system dynamics and relativistic physics.

Laser-Ultrasonic Testing and its Applications to Nuclear Reactor Internals

NASA Astrophysics Data System (ADS)

Ochiai, M.; Miura, T.; Yamamoto, S.

2008-02-01

A new nondestructive testing technique for surface-breaking microcracks in nuclear reactor components based on laser-ultrasonics is developed. Surface acoustic wave generated by Q-switched Nd:YAG laser and detected by frequency-stabilized long pulse laser coupled with confocal Fabry-Perot interferometer is used to detect and size the cracks. A frequency-domain signal processing is developed to realize accurate sizing capability. The laser-ultrasonic testing allows the detection of surface-breaking microcrack having a depth of less than 0.1 mm, and the measurement of their depth with an accuracy of 0.2 mm when the depth exceeds 0.5 mm including stress corrosion cracking. The laser-ultrasonic testing system combined with laser peening system, which is another laser-based maintenance technology to improve surface stress, for inner surface of small diameter tube is developed. The generation laser in the laser-ultrasonic testing system can be identical to the laser source of the laser peening. As an example operation of the system, the system firstly works as the laser-ultrasonic testing mode and tests the inner surface of the tube. If no cracks are detected, the system then changes its work mode to the laser peening and improves surface stress to prevent crack initiation. The first nuclear industrial application of the laser-ultrasonic testing system combined with the laser peening was completed in Japanese nuclear power plant in December 2004.

Control over high peak-power laser light and laser-driven X-rays

NASA Astrophysics Data System (ADS)

Zhao, Baozhen; Banerjee, Sudeep; Yan, Wenchao; Zhang, Ping; Zhang, Jun; Golovin, Grigory; Liu, Cheng; Fruhling, Colton; Haden, Daniel; Chen, Shouyuan; Umstadter, Donald

2018-04-01

An optical system was demonstrated that enables continuous control over the peak power level of ultrashort duration laser light. The optical characteristics of amplified and compressed femtosecond-duration light from a chirped-pulse amplification laser are shown to remain invariant and maintain high-fidelity using this system. When the peak power was varied by an order-of-magnitude, up to its maximum attainable value, the phase, spectral bandwidth, polarization state, and focusability of the light remained constant. This capability led to precise control of the focused laser intensity and enabled a correspondingly high level of control over the power of an all-laser-driven Thomson X-ray light source.

Advanced Wavefront Control Techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olivier, S S; Brase, J M; Avicola, K

2001-02-21

Programs at LLNL that involve large laser systems--ranging from the National Ignition Facility to new tactical laser weapons--depend on the maintenance of laser beam quality through precise control of the optical wavefront. This can be accomplished using adaptive optics, which compensate for time-varying aberrations that are often caused by heating in a high-power laser system. Over the past two decades, LLNL has developed a broad capability in adaptive optics technology for both laser beam control and high-resolution imaging. This adaptive optics capability has been based on thin deformable glass mirrors with individual ceramic actuators bonded to the back. In themore » case of high-power lasers, these adaptive optics systems have successfully improved beam quality. However, as we continue to extend our applications requirements, the existing technology base for wavefront control cannot satisfy them. To address this issue, this project studied improved modeling tools to increase our detailed understanding of the performance of these systems, and evaluated novel approaches to low-order wavefront control that offer the possibility of reduced cost and complexity. We also investigated improved beam control technology for high-resolution wavefront control. Many high-power laser systems suffer from high-spatial-frequency aberrations that require control of hundreds or thousands of phase points to provide adequate correction. However, the cost and size of current deformable mirrors can become prohibitive for applications requiring more than a few tens of phase control points. New phase control technologies are becoming available which offer control of many phase points with small low-cost devices. The goal of this project was to expand our wavefront control capabilities with improved modeling tools, new devices that reduce system cost and complexity, and extensions to high spatial and temporal frequencies using new adaptive optics technologies. In FY 99, the second year of this project, work was performed in four areas (1) advanced modeling tools for deformable mirrors (2) low-order wavefront correctors with Alvarez lenses, (3) a direct phase measuring heterdyne wavefront sensor, and (4) high-spatial-frequency wavefront control using spatial light modulators.« less

Advanced laser modeling with BLAZE multiphysics

NASA Astrophysics Data System (ADS)

Palla, Andrew D.; Carroll, David L.; Gray, Michael I.; Suzuki, Lui

2017-01-01

The BLAZE Multiphysics™ software simulation suite was specifically developed to model highly complex multiphysical systems in a computationally efficient and highly scalable manner. These capabilities are of particular use when applied to the complexities associated with high energy laser systems that combine subsonic/transonic/supersonic fluid dynamics, chemically reacting flows, laser electronics, heat transfer, optical physics, and in some cases plasma discharges. In this paper we present detailed cw and pulsed gas laser calculations using the BLAZE model with comparisons to data. Simulations of DPAL, XPAL, ElectricOIL (EOIL), and the optically pumped rare gas laser were found to be in good agreement with experimental data.

The magic of relay mirrors

NASA Astrophysics Data System (ADS)

Duff, Edward A.; Washburn, Donald C.

2004-09-01

Laser weapon systems would be significantly enhanced with the addition of high altitude or space-borne relay mirrors. Such mirrors, operating alone with a directed energy source, or many in a series fashion, can be shown to effectively move the laser source to the last, so-called fighting mirror. This "magically" reduces the range to target and offers to enhance the performance of directed energy systems like the Airborne Laser and even ground-based or ship-based lasers. Recent development of high altitude airships will be shown to provide stationary positions for such relay mirrors thereby enabling many new and important applications for laser weapons. The technical challenges to achieve this capability are discussed.

IEMIS (Integrated Emergency Management Information System) Floodplain Mapping Based on a Lidar Derived Data Set.

DTIC Science & Technology

1988-02-05

0-A193 971 IEMIS (INTEGRATED EMERGENCY MANAGEMENT INFORMATION SYSTEM ) FLOODPLRIN MAP.. (U) ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG HS J...illustrate the application of the automated mapping capabilities of the Integrated Emergency Management Information System (IEMIS) to FISs. Unclassified...mapping capabilities of the Integrated Emergency Management Information System (IEMIS) to FISs. II. BACKGROUND The concept of mounting laser ranging

Laser micro machining of medical devices.

PubMed

Rausch, Y

2009-01-01

Excimer and increasingly ultra-short-pulsed lasers are important tools in the creation of microstructures and nanostructures. Capabilities of the latest systems are described, which include drilling 30-microm diameter holes in 50 to 100 microm thick metal foils and subsurface engraving of transparent materials.

Fixed-wavelength H2O absorption spectroscopy system enhanced by an on-board external-cavity diode laser

NASA Astrophysics Data System (ADS)

Brittelle, Mack S.; Simms, Jean M.; Sanders, Scott T.; Gord, James R.; Roy, Sukesh

2016-03-01

We describe a system designed to perform fixed-wavelength absorption spectroscopy of H2O vapor in practical combustion devices. The system includes seven wavelength-stabilized distributed feedback (WSDFB) lasers, each with a spectral accuracy of  ±1 MHz. An on-board external cavity diode laser (ECDL) that tunes 1320-1365 nm extends the capabilities of the system. Five system operation modes are described. In one mode, a sweep of the ECDL is used to monitor each WSDFB laser wavelength with an accuracy of  ±30 MHz. Demonstrations of fixed-wavelength thermometry at 10 kHz bandwidth in near-room-temperature gases are presented; one test reveals a temperature measurement error of ~0.43%.

Laser ignition

DOEpatents

Early, James W.; Lester, Charles S.

2002-01-01

In the apparatus of the invention, a first excitation laser or other excitation light source capable of producing alternating beams of light having different wavelengths is used in tandem with one or more ignitor lasers to provide a compact, durable, engine deployable fuel ignition laser system. Reliable fuel ignition is provided over a wide range of fuel conditions by using the single remote excitation light source for pumping one or more small lasers located proximate to one or more fuel combustion zones with alternating wavelengths of light.

Compact Laser System for Field Deployable Ultracold Atom Sensors

NASA Astrophysics Data System (ADS)

Pino, Juan; Luey, Ben; Anderson, Mike

2013-05-01

As ultracold atom sensors begin to see their way to the field, there is a growing need for small, accurate, and robust laser systems to cool and manipulate atoms for sensing applications such as magnetometers, gravimeters, atomic clocks and inertial sensing. In this poster we present a laser system for Rb, roughly the size of a paperback novel, capable of generating and controlling light sufficient for the most complicated of cold atom sensors. The system includes >100dB of non-mechanical, optical shuttering, the ability to create short, microsecond pulses, a Demux stage to port light onto different optical paths, and an atomically referenced, frequency agile laser source. We will present data to support the system, its Size Weight and Power (SWaP) requirements, as well as laser stability and performance. funded under DARPA

Applications of laser-induced breakdown spectrometry (LIBS) in surface analysis.

PubMed

Vadillo, J M; Palanco, S; Romero, M D; Laserna, J J

1996-07-01

The applicability of laser-induced breakdown spectrometry (LIBS) for surface analysis is presented in terms of its lateral and depth resolution. A pulsed N(2) laser at 337.1 nm (3.65 J/cm(2)) was used to irradiate solar cells employed for photovoltaic energy production. Laser produced plasmas were collected and detected using a charge-coupled device. An experimental device developed in the laboratory permits an exact synchronization of sample positioning using an XY motorized system with laser pulses. Multielement analysis with lateral resolution of up to 30 microm is feasible with the present system. Three-dimensional capabilities of the system are used for studies on the distribution of carbon impurities at the surface of the solar cells.

New laser glass for short pulsed laser applications: the BLG80 (Conference Presentation)

NASA Astrophysics Data System (ADS)

George, Simi A.

2017-03-01

For achieving highest peak powers in a solid state laser (SSL) system, significant energy output and short pulses are necessary. For mode-locked lasers, it is well-known from the Fourier theorem that the largest gain bandwidths produce the narrowest pulse-widths; thus are transform limited. For an inhomogeneously broadened line width of a laser medium, if the intensity of pulses follow a Gaussian function, then the resulting mode-locked pulse will have a Gaussian shape with the emission bandwidth/pulse duration relationship of pulse ≥ 0.44?02/c. Thus, for high peak power SSL systems, laser designers incorporate gain materials capable of broad emission bandwidths. Available energy outputs from a phosphate glass host doped with rare-earth ions are unparalleled. Unfortunately, the emission bandwidths achievable from glass based gain materials are typically many factors smaller when compared to the Ti:Sapphire crystal. In order to overcome this limitation, a hybrid "mixed" laser glass amplifier - OPCPA approach was developed. The Texas petawatt laser that is currently in operation at the University of Texas-Austin and producing high peak powers uses this hybrid architecture. In this mixed-glass laser design, a phosphate and a silicate glass is used in series to achieve a broader bandwidth required before compression. Though proven, this technology is still insufficient for the future compact petawatt and exawatt systems capable of producing high energies and shorter pulse durations. New glasses with bandwidths that are two and three times larger than what is now available from glass hosts is needed if there is to be an alternative to Ti:Sapphire for laser designers. In this paper, we present new materials that may meet the necessary characteristics and demonstrate the laser and emission characteristics these through the internal and external studies.

Application of a pulsed laser for measurements of bathymetry and algal fluorescence.

NASA Technical Reports Server (NTRS)

Hickman, G. D.; Hogg, J. E.; Friedman, E. J.; Ghovanlou, A. H.

1973-01-01

The technique of measuring water depths with an airborne pulsed dye laser is studied, with emphasis on the degrading effect of some environmental and operational parameters on the transmitted and reflected laser signals. Extrapolation of measurements of laser stimulated fluorescence, performed as a function of both the algal cell concentration and the distance between the algae and the laser/receiver, indicate that a laser system operating from a height of 500 m should be capable of detecting chlorophyll concentrations as low as 1.0 mg/cu m.-

Enhanced erosion of tungsten plasma-facing components subject to simultaneous heat pulses and deuterium plasma

NASA Astrophysics Data System (ADS)

Umstadter, K. R.; Doerner, R.; Tynan, G.

2009-04-01

When an ELM occurs in tokamaks, up to 30% of the pedestal energy can be deposited on the wall of the tokamak causing heating and material loss due to sublimation/evaporation and melt layer splashing of plasma-facing components (PFCs) and expansion of the ejected material into the plasma. A short-pulse laser system capable of reproducing the thermal load of an ELM heat pulse has been integrated into the existing PFC research program in PISCES, a laboratory facility capable of reproducing plasma-materials interactions expected during normal operation of large tokamaks. An Nd:YAG laser capable of delivering up to 1 J of energy over a 7 ns pulsewidth is used for the experiments. Laser heat pulse only, H +/D + plasma only, and laser plus plasma experiments were conducted and initial results indicate enhanced erosion of tungsten exposed to simultaneous plasma and heat pulses, as compared to exposure to separate plasma-only or heat pulse-only conditions.

Radiotherapy using a laser proton accelerator

NASA Astrophysics Data System (ADS)

Murakami, Masao; Hishikawa, Yoshio; Miyajima, Satoshi; Okazaki, Yoshiko; Sutherland, Kenneth L.; Abe, Mitsuyuki; Bulanov, Sergei V.; Daido, Hiroyuki; Esirkepov, Timur Zh.; Koga, James; Yamagiwa, Mitsuru; Tajima, Toshiki

2008-06-01

Laser acceleration promises innovation in particle beam therapy of cancer where an ultra-compact accelerator system for cancer beam therapy can become affordable to a broad range of patients. This is not feasible without the introduction of a technology that is radically different from the conventional accelerator-based approach. Because of its compactness and other novel characteristics, the laser acceleration method provides many enhanced capabilities

Comprehensive description of the Orion laser facility

NASA Astrophysics Data System (ADS)

Hopps, Nicholas; Oades, Kevin; Andrew, Jim; Brown, Colin; Cooper, Graham; Danson, Colin; Daykin, Simon; Duffield, Stuart; Edwards, Ray; Egan, David; Elsmere, Stephen; Gales, Steve; Girling, Mark; Gumbrell, Edward; Harvey, Ewan; Hillier, David; Hoarty, David; Horsfield, Colin; James, Steven; Leatherland, Alex; Masoero, Stephen; Meadowcroft, Anthony; Norman, Michael; Parker, Stefan; Rothman, Stephen; Rubery, Michael; Treadwell, Paul; Winter, David; Bett, Thomas

2015-06-01

The Orion laser facility at the atomic weapons establishment (AWE) in the UK has been operational since April 2013, fielding experiments that require both its long and short pulse capability. This paper provides a full description of the facility in terms of laser performance, target systems and diagnostics currently available. Inevitably, this is a snapshot of current capability—the available diagnostics and the laser capability are evolving continuously. The laser systems consist of ten beams, optimised around 1 ns pulse duration, which each provide a nominal 500 J at a wavelength of 351 nm. There are also two short pulse beams, which each provide 500 J in 0.5 ps at 1054 nm. There are options for frequency doubling one short pulse beam to enhance the pulse temporal contrast. More recently, further contrast enhancement, based on optical parametric amplification (OPA) in the front end with a pump pulse duration of a few ps, has been installed. An extensive suite of diagnostics are available for users, probing the optical emission, x-rays and particles produced in laser-target interactions. Optical probe diagnostics are also available. A description of the diagnostics is provided.

The Marine Corps Needs a Targeting, Sensors, and Surveillance Systems Operational Integration and Support Team

DTIC Science & Technology

2010-03-02

triggerman is probably still close ; lately all IEDs in the area have been initiated via command-wire. The squad leader sets a cordon, ensures an IED 9...Operational Surveillance System (G-BOSS) with a Class IIIb laser pointer. This class of laser requires users to receive a laser safety class...2) The Keyhole kit of surveillance equipment. Designed to provide “snipers with an increased capability to visually detect the enemy emplacing IEDs

Optical probing of high intensity laser interaction with micron-sized cryogenic hydrogen jets

NASA Astrophysics Data System (ADS)

Ziegler, Tim; Rehwald, Martin; Obst, Lieselotte; Bernert, Constantin; Brack, Florian-Emanuel; Curry, Chandra B.; Gauthier, Maxence; Glenzer, Siegfried H.; Göde, Sebastian; Kazak, Lev; Kraft, Stephan D.; Kuntzsch, Michael; Loeser, Markus; Metzkes-Ng, Josefine; Rödel, Christian; Schlenvoigt, Hans-Peter; Schramm, Ulrich; Siebold, Mathias; Tiggesbäumker, Josef; Wolter, Steffen; Zeil, Karl

2018-07-01

Probing the rapid dynamics of plasma evolution in laser-driven plasma interactions provides deeper understanding of experiments in the context of laser-driven ion acceleration and facilitates the interplay with complementing numerical investigations. Besides the microscopic scales involved, strong plasma (self-)emission, predominantly around the harmonics of the driver laser, often complicates the data analysis. We present the concept and the implementation of a stand-alone probe laser system that is temporally synchronized to the driver laser, providing probing wavelengths beyond the harmonics of the driver laser. The capability of this system is shown during a full-scale laser proton acceleration experiment using renewable cryogenic hydrogen jet targets. For further improvements, we studied the influence of probe color, observation angle of the probe and temporal contrast of the driver laser on the probe image quality.

Towards in vivo laser coagulation and concurrent optical coherence tomography through double-clad fiber devices

NASA Astrophysics Data System (ADS)

Beaudette, Kathy; Lo, William; Villiger, Martin; Shishkov, Milen; Godbout, Nicolas; Bouma, Brett E.; Boudoux, Caroline

2016-03-01

There is a strong clinical need for an optical coherence tomography (OCT) system capable of delivering concurrent coagulation light enabling image-guided dynamic laser marking for targeted collection of biopsies, as opposed to a random sampling, to reduce false-negative findings. Here, we present a system based on double-clad fiber (DCF) capable of delivering pulsed laser light through the inner cladding while performing OCT through the core. A previously clinically validated commercial OCT system (NVisionVLE, Ninepoint Medical) was adapted to enable in vivo esophageal image-guided dynamic laser marking. An optimized DCF coupler was implemented into the system to couple both modalities into the DCF. A DCF-based rotary joint was used to couple light to the spinning DCF-based catheter for helical scanning. DCF-based OCT catheters, providing a beam waist diameter of 62μm at a working distance of 9.3mm, for use with a 17-mm diameter balloon sheath, were used for ex vivo imaging of a swine esophagus. Imaging results using the DCF-based clinical system show an image quality comparable with a conventional system with minimal crosstalk-induced artifacts. To further optimize DCF catheter optical design in order to achieve single-pulse marking, a Zemax model of the DCF output and its validation are presented.

Directed Nanopatterning with Nonlinear Laser Lithography

NASA Astrophysics Data System (ADS)

Tokel, Onur; Yavuz, Ozgun; Ergecen, Emre; Pavlov, Ihor; Makey, Ghaith; Ilday, Fatih Omer

In spite of the successes of maskless optical nanopatterning methods, it remains extremely challenging to create any isotropic, periodic nanopattern. Further, available optical techniques lack the long-range coverage and high periodicity demanded by photonics and photovoltaics applications. Here, we provide a novel solution with Nonlinear Laser Lithography (NLL) approach. Notably, we demonstrate that self-organized nanopatterns can be produced in all possible Bravais lattice types. Further, we show that carefully chosen defects or structued noise can direct NLL symmetries. Exploitation of directed self-organizatio to select or guide to predetermined symmetries is a new capability. Predictive capabilities for such far-from-equilibrium, dissipative systems is very limited due to a lack of experimental systems with predictive models. Here we also present a completely predictive model, and experimentally confirm that the emergence of motifs can be regulated by engineering defects, while the polarization of the ultrafast laser prescribes lattice symmetry, which in turn reinforces translational invariance. Thus, NLL enables a novel, maskless nanofabrication approach, where laser-induced nanopatterns can be rapidly created in any lattice symmetry

Rapid long-wave infrared laser-induced breakdown spectroscopy measurements using a mercury-cadmium-telluride linear array detection system.

PubMed

Yang, Clayton S-C; Brown, Eiei; Kumi-Barimah, Eric; Hommerich, Uwe; Jin, Feng; Jia, Yingqing; Trivedi, Sudhir; D'souza, Arvind I; Decuir, Eric A; Wijewarnasuriya, Priyalal S; Samuels, Alan C

2015-11-20

In this work, we develop a mercury-cadmium-telluride linear array detection system that is capable of rapidly capturing (∼1-5  s) a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared (LWIR) region (∼5.6-10  μm). Similar to the conventional UV-Vis LIBS, a broadband emission spectrum of condensed phase samples covering the whole 5.6-10 μm region can be acquired from just a single laser-induced microplasma or averaging a few single laser-induced microplasmas. Atomic and molecular signature emission spectra of solid inorganic and organic tablets and thin liquid films deposited on a rough asphalt surface are observed. This setup is capable of rapidly probing samples "as is" without the need of elaborate sample preparation and also offers the possibility of a simultaneous UV-Vis and LWIR LIBS measurement.

A low-cost photoacoustic microscopy system with a laser diode excitation

PubMed Central

Wang, Tianheng; Nandy, Sreyankar; Salehi, Hassan S.; Kumavor, Patrick D.; Zhu, Quing

2014-01-01

Photoacoustic microscopy (PAM) is capable of mapping microvasculature networks in biological tissue and has demonstrated great potential for biomedical applications. However, the clinical application of the PAM system is limited due to the use of bulky and expensive pulsed laser sources. In this paper, a low-cost optical-resolution PAM system with a pulsed laser diode excitation has been introduced. The lateral resolution of this PAM system was estimated to be 7 µm by imaging a carbon fiber. The phantoms made of polyethylene tubes filled with blood and a mouse ear were imaged to demonstrate the feasibility of this PAM system for imaging biological tissues. PMID:25401019

Evaluation of the propulsion control system of a planetary rover and design of a mast for an elevation scanning laser/multi-detector system

NASA Technical Reports Server (NTRS)

Knaub, D.; Yerazunis, S. W.

1978-01-01

Vertical wheel loads, wheel speeds, and torque relationships are considered in the design of a propulsion system capable of responding to steering, slope climbing, and irregular local terrains. The system developed is applied to the RPI Mars roving vehicle. The mechanical system required to implement the elevation laser scanning/multidetector principle was the design and construction of a mechanical system for implementing the elevation scanning/multidetector principle is also discussed.

Ground-Based and Space-Based Laser Beam Power Applications

NASA Technical Reports Server (NTRS)

Bozek, John M.

1995-01-01

A space power system based on laser beam power is sized to reduce mass, increase operational capabilities, and reduce complexity. The advantages of laser systems over solar-based systems are compared as a function of application. Power produced from the conversion of a laser beam that has been generated on the Earth's surface and beamed into cislunar space resulted in decreased round-trip time for Earth satellite electric propulsion tugs and a substantial landed mass savings for a lunar surface mission. The mass of a space-based laser system (generator in space and receiver near user) that beams down to an extraterrestrial airplane, orbiting spacecraft, surface outpost, or rover is calculated and compared to a solar system. In general, the advantage of low mass for these space-based laser systems is limited to high solar eclipse time missions at distances inside Jupiter. The power system mass is less in a continuously moving Mars rover or surface outpost using space-based laser technology than in a comparable solar-based power system, but only during dust storm conditions. Even at large distances for the Sun, the user-site portion of a space-based laser power system (e.g., the laser receiver component) is substantially less massive than a solar-based system with requisite on-board electrochemical energy storage.

Pulse-burst laser systems for fast Thomson scattering (invited)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Den Hartog, D. J.; Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of Wisconsin-Madison, Madison, Wisconsin 53706; Ambuel, J. R.

2010-10-15

Two standard commercial flashlamp-pumped Nd:YAG (YAG denotes yttrium aluminum garnet) lasers have been upgraded to ''pulse-burst'' capability. Each laser produces a burst of up to 15 2 J Q-switched pulses (1064 nm) at repetition rates of 1-12.5 kHz. Variable pulse-width drive (0.15-0.39 ms) of the flashlamps is accomplished by insulated gate bipolar transistor (IGBT) switching of electrolytic capacitor banks. Direct control of the laser Pockels cell drive enables optimal pulse energy extraction, and up to four 2 J laser pulses during one flashlamp pulse. These lasers are used in the Thomson scattering plasma diagnostic system on the MST reversed-field pinchmore » to record the dynamic evolution of the electron temperature profile and temperature fluctuations. To further these investigations, a custom pulse-burst laser system with a maximum pulse repetition rate of 250 kHz is now being commissioned.« less

Spatio-temporally resolved spectral measurements of laser-produced plasma and semiautomated spectral measurement-control and analysis software

NASA Astrophysics Data System (ADS)

Cao, S. Q.; Su, M. G.; Min, Q.; Sun, D. X.; O'Sullivan, G.; Dong, C. Z.

2018-02-01

A spatio-temporally resolved spectral measurement system of highly charged ions from laser-produced plasmas is presented. Corresponding semiautomated computer software for measurement control and spectral analysis has been written to achieve the best synchronicity possible among the instruments. This avoids the tedious comparative processes between experimental and theoretical results. To demonstrate the capabilities of this system, a series of spatio-temporally resolved experiments of laser-produced Al plasmas have been performed and applied to benchmark the software. The system is a useful tool for studying the spectral structures of highly charged ions and for evaluating the spatio-temporal evolution of laser-produced plasmas.

Sub-Nanosecond Cinematography In Laser Fusion Research: Current Techniques And Applications At The Lawrence Livermore National Laboratory*

NASA Astrophysics Data System (ADS)

Coleman, Lamar W...

1985-02-01

Progress in laser fusion research has increased the need for detail and precision in the diagnosis of experiments. This has spawned the development and use of sophisticated sub-nanosecond resolution diavostic systems. These systems typically use ultrafast x-ray or optical streak caAleras in combination. with spatially imaging or spectrally dispersing elements. These instruments provide high resolution data essential for understanding the processes occurrilltg in the interaction. of high. intensity laser light with targets. Several of these types of instruments and their capabilities will be discussed. The utilization of these kinds of diagnostics systems on the nearly completed 100 kJ Nova laser facility will be described.

Sub-nanosecond cinematography in laser fusion research: Current techniques and applications at the Lawrence Livermore Laboratory

NASA Astrophysics Data System (ADS)

Coleman, L. W.

1985-01-01

Progress in laser fusion research has increased the need for detail and precision in the diagnosis of experiments. This has spawned the development and use of sophisticated sub-nanosecond resolution diagnostic systems. These systems typically use ultrafast X-ray or optical streak cameras in combination with spatially imaging or spectrally dispersing elements. These instruments provide high resolution data essential for understanding the processes occurring in the interaction of high intensity laser light with targets. Several of these types of instruments and their capabilities will be discussed. The utilization of these kinds of diagnostics systems on the nearly completed 100 kJ Nova laser facility will be described.

Navy/Marine Corps innovative science and technology developments for future enhanced mine detection capabilities

NASA Astrophysics Data System (ADS)

Holloway, John H., Jr.; Witherspoon, Ned H.; Miller, Richard E.; Davis, Kenn S.; Suiter, Harold R.; Hilton, Russell J.

2000-08-01

JMDT is a Navy/Marine Corps 6.2 Exploratory Development program that is closely coordinated with the 6.4 COBRA acquisition program. The objective of the program is to develop innovative science and technology to enhance future mine detection capabilities. The objective of the program is to develop innovative science and technology to enhance future mine detection capabilities. Prior to transition to acquisition, the COBRA ATD was extremely successful in demonstrating a passive airborne multispectral video sensor system operating in the tactical Pioneer unmanned aerial vehicle (UAV), combined with an integrated ground station subsystem to detect and locate minefields from surf zone to inland areas. JMDT is investigating advanced technology solutions for future enhancements in mine field detection capability beyond the current COBRA ATD demonstrated capabilities. JMDT has recently been delivered next- generation, innovative hardware which was specified by the Coastal System Station and developed under contract. This hardware includes an agile-tuning multispectral, polarimetric, digital video camera and advanced multi wavelength laser illumination technologies to extend the same sorts of multispectral detections from a UAV into the night and over shallow water and other difficult littoral regions. One of these illumination devices is an ultra- compact, highly-efficient near-IR laser diode array. The other is a multi-wavelength range-gateable laser. Additionally, in conjunction with this new technology, algorithm enhancements are being developed in JMDT for future naval capabilities which will outperform the already impressive record of automatic detection of minefields demonstrated by the COBAR ATD.

High energy laser demonstrators for defense applications

NASA Astrophysics Data System (ADS)

Jung, M.; Riesbeck, Th.; Schmitz, J.; Baumgärtel, Th.; Ludewigt, K.; Graf, A.

2017-01-01

Rheinmetall Waffe Munition has worked since 30 years in the area of High Energy Laser (HEL) for defence applications, starting from pulsed CO2 to pulsed glass rods lasers. In the last decade Rheinmetall Waffe Munition changed to diode pumped solid state laser (DPSSL) technology and has successfully developed, realised and tested a variety of versatile HEL weapon demonstrators for air- and ground defence scenarios like countering rocket, artillery, mortar, missile (RAMM), unmanned aerial systems (UAS) and unexploded ordnances clearing. By employing beam superimposing technology and a modular laser weapon concept, the total optical power has been successively increased. Stationary weapon platforms, military vehicles and naval platforms have been equipped with high energy laser effectors. The contribution gives a summary of the most recent development stages of Rheinmetalls HEL weapon program. In addition to the stationary 30 kW laser weapon demonstrator, we present vehicle based HEL demonstrators: the 5 kW class Mobile HEL Effector Track V, the 20 kW class Mobile HEL Effector Wheel XX and the 50 kW class Mobile HEL Effector Container L and the latest 10 kW HEL effector integrated in the naval weapon platform MLG 27. We describe the capabilities of these demonstrators against different potential targets. Furthermore, we will show the capability of the 30 kW stationary Laser Weapon Demonstrator integrated into an existing ground based air defence system to defeat saturated attacks of RAMM and UAS targets.

Bridging the Gap. European C4ISR Capabilities and Transatlantic Interoperability

DTIC Science & Technology

2004-10-01

Messagerie Universelle Sécurisée, or MUSE), and the Airborne Laser Optical Link (Liaison Optique Laser Aéroportée, or LOLA), a demonstrator that in 2006...system) Future naval intranet system Messagerie Universelle Sécurisée (MUSE) (secure e-mail system for French MOD) Secure e-mail system...EU/NATO relationship so progress can continue in both frameworks. In addition, whether through the EU or NATO, a failure to allocate European fiscal

Closed loop control of penetration depth during CO₂ laser lap welding processes.

PubMed

Sibillano, Teresa; Rizzi, Domenico; Mezzapesa, Francesco P; Lugarà, Pietro Mario; Konuk, Ali Riza; Aarts, Ronald; Veld, Bert Huis In 't; Ancona, Antonio

2012-01-01

In this paper we describe a novel spectroscopic closed loop control system capable of stabilizing the penetration depth during laser welding processes by controlling the laser power. Our novel approach is to analyze the optical emission from the laser generated plasma plume above the keyhole, to calculate its electron temperature as a process-monitoring signal. Laser power has been controlled by using a quantitative relationship between the penetration depth and the plasma electron temperature. The sensor is able to correlate in real time the difference between the measured electron temperature and its reference value for the requested penetration depth. Accordingly the closed loop system adjusts the power, thus maintaining the penetration depth.

Closed Loop Control of Penetration Depth during CO2 Laser Lap Welding Processes

PubMed Central

Sibillano, Teresa; Rizzi, Domenico; Mezzapesa, Francesco P.; Lugarà, Pietro Mario; Konuk, Ali Riza; Aarts, Ronald; Veld, Bert Huis in 't; Ancona, Antonio

2012-01-01

In this paper we describe a novel spectroscopic closed loop control system capable of stabilizing the penetration depth during laser welding processes by controlling the laser power. Our novel approach is to analyze the optical emission from the laser generated plasma plume above the keyhole, to calculate its electron temperature as a process-monitoring signal. Laser power has been controlled by using a quantitative relationship between the penetration depth and the plasma electron temperature. The sensor is able to correlate in real time the difference between the measured electron temperature and its reference value for the requested penetration depth. Accordingly the closed loop system adjusts the power, thus maintaining the penetration depth. PMID:23112646

Progress In Developing Laser Based Post Irradiation Examination Infrastructure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, James A.; Scott, Clark L.; Benefiel, Brad C.

To be able to understand the performance of reactor fuels and materials, irradiated materials must be characterized effectively and efficiently in a high rad environment. The characterization work must be performed remotely and in an environment hostile to instrumentation. Laser based characterization techniques provide the ability to be remote and robust in a hot-cell environment. Laser based instrumentation also can provide high spatial resolution suitable for scanning and imaging large areas. The INL is currently developing three laser based Post Irradiation Examination (PIE) stations for the Hot Fuel Examination Facility at the INL. These laser based systems will characterize irradiatedmore » materials and fuels. The characterization systems are the following: Laser Shock Laser based ultrasonic C-scan system Gas Assay, Sample, and Recharge system (GASR, up-grade to an existing system). The laser shock technique will characterize material properties and failure loads/mechanisms in various materials such as LWR fuel, plate fuel, and next generation fuel forms, for PIE in high radiation areas. The laser shock-technique induces large amplitude shock waves to mechanically characterize interfaces such as the fuel-clad bond. The shock wave travels as a compression wave through the material to the free (unconfined) back surface and reflects back through the material under test as a rarefaction (tensile) wave. This rarefaction wave is the physical mechanism that produces internal de-lamination failure. As part of the laser shock system, a laser-based ultrasonic C-scan system will be used to detect and characterize debonding caused by the laser shock technique. The laser ultrasonic system will be fully capable of performing classical non-destructive evaluation testing and imaging functions such as microstructure characterization, flaw detection and dimensional metrology in complex components. The purpose of the GASR is to measure the pressure/volume of the plenum of an irradiated fuel element and obtain fission gas samples for analysis. The study of pressure and volume in the plenum of an irradiated fuel element and the analysis of fission gases released from the fuel is important to understanding the performance of reactor fuels and materials. This system may also be used to measure the pressure/volume of other components (such as control blades) and obtain gas samples from these components for analysis. The main function of the laser in this application is to puncture the fuel element to allow the fission gas to escape and if necessary to weld the spot close. The GASR station will have the inherent capability to perform cutting welding and joining functions within a hot-cell.« less

Airborne Optical Systems Test Bed (AOSTB)

DTIC Science & Technology

2016-07-01

resident laser radar platform with roll -on/ roll -off sensor capability. The new platform provides The Laboratory with an added capability of leveraging...29 Figure 11 – Finite Element Analysis of Loads on Isolators (9G Forward...This project created a resident sensor suite with roll -on/ roll -off capability, coupled to a resident platform (Twin Otter Aircraft). This facility

LLIMAS: Revolutionizing integrating modeling and analysis at MIT Lincoln Laboratory

NASA Astrophysics Data System (ADS)

Doyle, Keith B.; Stoeckel, Gerhard P.; Rey, Justin J.; Bury, Mark E.

2017-08-01

MIT Lincoln Laboratory's Integrated Modeling and Analysis Software (LLIMAS) enables the development of novel engineering solutions for advanced prototype systems through unique insights into engineering performance and interdisciplinary behavior to meet challenging size, weight, power, environmental, and performance requirements. LLIMAS is a multidisciplinary design optimization tool that wraps numerical optimization algorithms around an integrated framework of structural, thermal, optical, stray light, and computational fluid dynamics analysis capabilities. LLIMAS software is highly extensible and has developed organically across a variety of technologies including laser communications, directed energy, photometric detectors, chemical sensing, laser radar, and imaging systems. The custom software architecture leverages the capabilities of existing industry standard commercial software and supports the incorporation of internally developed tools. Recent advances in LLIMAS's Structural-Thermal-Optical Performance (STOP), aeromechanical, and aero-optical capabilities as applied to Lincoln prototypes are presented.

High-power VCSELs for smart munitions

NASA Astrophysics Data System (ADS)

Geske, Jon; MacDougal, Michael; Cole, Garrett; Snyder, Donald

2006-08-01

The next generation of low-cost smart munitions will be capable of autonomously detecting and identifying targets aided partly by the ability to image targets with compact and robust scanning rangefinder and LADAR capabilities. These imaging systems will utilize arrays of high performance, low-cost semiconductor diode lasers capable of achieving high peak powers in pulses ranging from 5 to 25 nanoseconds in duration. Aerius Photonics is developing high-power Vertical-Cavity Surface-Emitting Lasers (VCSELs) to meet the needs of these smart munitions applications. The authors will report the results of Aerius' development program in which peak pulsed powers exceeding 60 Watts were demonstrated from single VCSEL emitters. These compact packaged emitters achieved pulse energies in excess of 1.5 micro-joules with multi kilo-hertz pulse repetition frequencies. The progress of the ongoing effort toward extending this performance to arrays of VCSEL emitters and toward further improving laser slope efficiency will be reported.

Design of smart composite platforms for adaptive trust vector control and adaptive laser telescope for satellite applications

NASA Astrophysics Data System (ADS)

Ghasemi-Nejhad, Mehrdad N.

2013-04-01

This paper presents design of smart composite platforms for adaptive trust vector control (TVC) and adaptive laser telescope for satellite applications. To eliminate disturbances, the proposed adaptive TVC and telescope systems will be mounted on two analogous smart composite platform with simultaneous precision positioning (pointing) and vibration suppression (stabilizing), SPPVS, with micro-radian pointing resolution, and then mounted on a satellite in two different locations. The adaptive TVC system provides SPPVS with large tip-tilt to potentially eliminate the gimbals systems. The smart composite telescope will be mounted on a smart composite platform with SPPVS and then mounted on a satellite. The laser communication is intended for the Geosynchronous orbit. The high degree of directionality increases the security of the laser communication signal (as opposed to a diffused RF signal), but also requires sophisticated subsystems for transmission and acquisition. The shorter wavelength of the optical spectrum increases the data transmission rates, but laser systems require large amounts of power, which increases the mass and complexity of the supporting systems. In addition, the laser communication on the Geosynchronous orbit requires an accurate platform with SPPVS capabilities. Therefore, this work also addresses the design of an active composite platform to be used to simultaneously point and stabilize an intersatellite laser communication telescope with micro-radian pointing resolution. The telescope is a Cassegrain receiver that employs two mirrors, one convex (primary) and the other concave (secondary). The distance, as well as the horizontal and axial alignment of the mirrors, must be precisely maintained or else the optical properties of the system will be severely degraded. The alignment will also have to be maintained during thruster firings, which will require vibration suppression capabilities of the system as well. The innovative platform has been designed to have tip-tilt pointing and simultaneous multi-degree-of-freedom vibration isolation capability for pointing stabilization. Analytical approaches have been employed for determining the loads in the components as well as optimizing the design of the system. The different critical components such as telescope tube struts, flexure joints, and the secondary mirror mount have been designed and analyzed using finite element technique. The Simultaneous Precision Positioning and Vibration Suppression (SPPVS) smart composites platforms for the adaptive TVC and adaptive composite telescope are analogous (e.g., see work by Ghasemi-Nejhad and co-workers [1, 2]), where innovative concepts and control strategies are introduced, and experimental verifications of simultaneous thrust vector control and vibration isolation of satellites were performed. The smart composite platforms function as an active structural interface between the main thruster of a satellite and the satellite structure for the adaptive TVC application and as an active structural interface between the main smart composite telescope and the satellite structure for the adaptive laser communication application. The cascaded multiple feedback loops compensate the hysteresis (for piezoelectric stacks inside the three linear actuators that individually have simultaneous precision positioning and vibration suppression), dead-zone, back-lash, and friction nonlinearities very well, and provide precision and quick smart platform control and satisfactory thrust vector control capability. In addition, for example for the adaptive TVC, the experimental results show that the smart composite platform satisfactorily provided precision and fast smart platform control as well as the satisfactory thrust vector control capability. The vibration controller isolated 97% of the vibration energy due to the thruster firing.

Laser Journal

NASA Astrophysics Data System (ADS)

1991-12-01

The major results of an experimental study of a slab Nd:YAG laser are reported in the article; the laser was successfully developed by the authors. The major findings include the following: (1) a method for cooling the blended flowing air and water, as well the related experimental parameters; (2) by using a crossed lens cavity, the authors further improved the anomalous capability within the compensation cavity of the slab laser, as well as higher insensitivity of the system to maladjustment; and (3) a processing technique and major points of slab YAG laser medium.

Dual-wavelength quantum cascade laser for trace gas spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jágerská, J.; Tuzson, B.; Mangold, M.

2014-10-20

We demonstrate a sequentially operating dual-wavelength quantum cascade laser with electrically separated laser sections, emitting single-mode at 5.25 and 6.25 μm. Based on a single waveguide ridge, this laser represents a considerable asset to optical sensing and trace gas spectroscopy, as it allows probing multiple gas species with spectrally distant absorption features using conventional optical setups without any beam combining optics. The laser capability was demonstrated in simultaneous NO and NO{sub 2} detection, reaching sub-ppb detection limits and selectivity comparable to conventional high-end spectroscopic systems.

Raman beam combining for laser brightness enhancement

DOEpatents

Dawson, Jay W.; Allen, Graham S.; Pax, Paul H.; Heebner, John E.; Sridharan, Arun K.; Rubenchik, Alexander M.; Barty, Chrisopher B. J.

2015-10-27

An optical source capable of enhanced scaling of pulse energy and brightness utilizes an ensemble of single-aperture fiber lasers as pump sources, with each such fiber laser operating at acceptable pulse energy levels. Beam combining involves stimulated Raman scattering using a Stokes' shifted seed beam, the latter of which is optimized in terms of its temporal and spectral properties. Beams from fiber lasers can thus be combined to attain pulses with peak energies in excess of the fiber laser self-focusing limit of 4 MW while retaining the advantages of a fiber laser system of high average power with good beam quality.

Alternative laser system for cesium magneto-optical trap via optical injection locking to sideband of a 9-GHz current-modulated diode laser.

PubMed

Diao, Wenting; He, Jun; Liu, Zhi; Yang, Baodong; Wang, Junmin

2012-03-26

By optical injection of an 852-nm extended-cavity diode laser (master laser) to lock the + 1-order sideband of a ~9-GHz-current-modulated diode laser (slave laser), we generate a pair of phase-locked lasers with a frequency difference up to ~9-GHz for a cesium (Cs) magneto-optical trap (MOT) with convenient tuning capability. For a cesium MOT, the master laser acts as repumping laser, locked to the Cs 6S₁/₂ (F = 3) - 6P₃/₂ (F' = 4) transition. When the + 1-order sideband of the 8.9536-GHz-current-modulated slave laser is optically injection-locked, the carrier operates on the Cs 6S₁/₂ (F = 4) - 6P₃/₂ (F' = 5) cooling cycle transition with -12 MHz detuning and acts as cooling/trapping laser. When carrying a 9.1926-GHz modulation signal, this phase-locked laser system can be applied in the fields of coherent population trapping and coherent manipulation of Cs atomic ground states.

Laser cutting of irregular shape object based on stereo vision laser galvanometric scanning system

NASA Astrophysics Data System (ADS)

Qi, Li; Zhang, Yixin; Wang, Shun; Tang, Zhiqiang; Yang, Huan; Zhang, Xuping

2015-05-01

Irregular shape objects with different 3-dimensional (3D) appearances are difficult to be shaped into customized uniform pattern by current laser machining approaches. A laser galvanometric scanning system (LGS) could be a potential candidate since it can easily achieve path-adjustable laser shaping. However, without knowing the actual 3D topography of the object, the processing result may still suffer from 3D shape distortion. It is desirable to have a versatile auxiliary tool that is capable of generating 3D-adjusted laser processing path by measuring the 3D geometry of those irregular shape objects. This paper proposed the stereo vision laser galvanometric scanning system (SLGS), which takes the advantages of both the stereo vision solution and conventional LGS system. The 3D geometry of the object obtained by the stereo cameras is used to guide the scanning galvanometers for 3D-shape-adjusted laser processing. In order to achieve precise visual-servoed laser fabrication, these two independent components are integrated through a system calibration method using plastic thin film target. The flexibility of SLGS has been experimentally demonstrated by cutting duck feathers for badminton shuttle manufacture.

Countering MANPADS: study of new concepts and applications

NASA Astrophysics Data System (ADS)

Maltese, Dominique; Robineau, Jacques; Audren, Jean-Thierry; Aragones, Julien; Sailliot, Christophe

2006-05-01

The latest events of ground-to-air Man Portable Air Defense (MANPAD) attacks against aircraft have revealed a new threat both for military and civilian aircraft. Consequently, the implementation of Protecting systems (i.e. Directed InfraRed Counter Measure - DIRCM) in order to face IR guided missiles turns out to be now inevitable. In a near future, aircraft will have to possess detection, tracking, targeting and jamming capabilities to face single and multiple MANPAD threats fired in short-range scenarios from various environments (urban sites, landscape...). In this paper, a practical example of a DIRCM system under study at SAGEM DEFENSE & SECURITY company is presented. The self-protection solution includes built-in and automatic locking-on, tracking, identification and laser jamming capabilities, including defeat assessment. Target Designations are provided by a Missile Warning System. Multiple Target scenarios have been considered to design the system architecture. The article deals with current and future threats (IR seekers of different generations...), scenarios and platforms for system definition. Plus, it stresses on self-protection solutions based on laser jamming capability. Different strategies including target identification, multi band laser, active imagery are described. The self-protection system under study at SAGEM DEFENSE & SECURITY company is also a part of this chapter. Eventually, results of self-protection scenarios are provided for different MANPAD scenarios. Data have been obtained from a simulation software. The results highlight how the system reacts to incoming IR-guided missiles in short time scenarios.

Visible high-power laser sources for today and beyond

NASA Astrophysics Data System (ADS)

Smolka, Gregory L.

1995-04-01

The diversity and proliferation of 'real-world' laser applications continues to put increasing demand on laser technology. New system constraints, often dictated by the operation environment, stretch the capabilities of conventional laboratory lasers. As the applications proliferate, so too do the users. Today's laser user is often not a laser engineer, but rather views the laser simply as a tool to help him perform his job. For lasers to reach their true market potential, laser designers must respond to these user-mandated requirements with simple, compact, rugged devices. Traditional commercial lasers are far too large, bulky and complex for many of these new applications. Design techniques for shrinking, simplifying the ruggedizing solid-state lasers for today's applications will be discussed.

High power gas laser - Applications and future developments

NASA Technical Reports Server (NTRS)

Hertzberg, A.

1977-01-01

Fast flow can be used to create the population inversion required for lasing action, or can be used to improve laser operation, for example by the removal of waste heat. It is pointed out that at the present time all lasers which are capable of continuous high-average power employ flow as an indispensable aspect of operation. High power laser systems are discussed, taking into account the gasdynamic laser, the HF supersonic diffusion laser, and electric discharge lasers. Aerodynamics and high power lasers are considered, giving attention to flow effects in high-power gas lasers, aerodynamic windows and beam manipulation, and the Venus machine. Applications of high-power laser technology reported are related to laser material working, the employment of the laser in controlled fusion machines, laser isotope separation and photochemistry, and laser power transmission.

A lidar system for measuring atmospheric pressure and temperature profiles

NASA Technical Reports Server (NTRS)

Schwemmer, Geary K.; Dombrowski, Mark; Korb, C. Laurence; Milrod, Jeffry; Walden, Harvey

1987-01-01

The design and operation of a differential absorption lidar system capable of remotely measuring the vertical structure of tropospheric pressure and temperature are described. The measurements are based on the absorption by atmospheric oxygen of the spectrally narrowband output of two pulsed alexandrite lasers. Detailed laser output spectral characteristics, which are critical to successful lidar measurements, are presented. Spectral linewidths of 0.026 and 0.018 per cm for the lasers were measured with over 99.99 percent of the energy contained in three longitudinal modes.

Creation of backdoors in quantum communications via laser damage

NASA Astrophysics Data System (ADS)

Makarov, Vadim; Bourgoin, Jean-Philippe; Chaiwongkhot, Poompong; Gagné, Mathieu; Jennewein, Thomas; Kaiser, Sarah; Kashyap, Raman; Legré, Matthieu; Minshull, Carter; Sajeed, Shihan

2016-09-01

Practical quantum communication (QC) protocols are assumed to be secure provided implemented devices are properly characterized and all known side channels are closed. We show that this is not always true. We demonstrate a laser-damage attack capable of modifying device behavior on demand. We test it on two practical QC systems for key distribution and coin tossing, and show that newly created deviations lead to side channels. This reveals that laser damage is a potential security risk to existing QC systems, and necessitates their testing to guarantee security.

Scaling of Fiber Laser Systems Based on Novel Components and High Power Capable Packaging and Joining Technologies

DTIC Science & Technology

2010-09-01

l ri Laser Splicing / Welding r li i / l i Contact Bonding t t i Wafer Level Bonding Mineralic, Fusion . Anodic, Eutectic, Glass-frit, liquid...28-29 September 2010 SET-171 Mid-IR Fiber Laser Workshop partly sponsored by Tapering and splicing device as well as process control developed...Components Laser based splicing and tapering Multimode fiber (ø720µm) with spliced end cap (ø1500µm) © Fraunhofer IOF 28-29 September 2010 SET-171 Mid-IR

Depth profiling and imaging capabilities of an ultrashort pulse laser ablation time of flight mass spectrometer

PubMed Central

Cui, Yang; Moore, Jerry F.; Milasinovic, Slobodan; Liu, Yaoming; Gordon, Robert J.; Hanley, Luke

2012-01-01

An ultrafast laser ablation time-of-flight mass spectrometer (AToF-MS) and associated data acquisition software that permits imaging at micron-scale resolution and sub-micron-scale depth profiling are described. The ion funnel-based source of this instrument can be operated at pressures ranging from 10−8 to ∼0.3 mbar. Mass spectra may be collected and stored at a rate of 1 kHz by the data acquisition system, allowing the instrument to be coupled with standard commercial Ti:sapphire lasers. The capabilities of the AToF-MS instrument are demonstrated on metal foils and semiconductor wafers using a Ti:sapphire laser emitting 800 nm, ∼75 fs pulses at 1 kHz. Results show that elemental quantification and depth profiling are feasible with this instrument. PMID:23020378

Laser safety research and modeling for high-energy laser systems

NASA Astrophysics Data System (ADS)

Smith, Peter A.; Montes de Oca, Cecilia I.; Kennedy, Paul K.; Keppler, Kenneth S.

2002-06-01

The Department of Defense has an increasing number of high-energy laser weapons programs with the potential to mature in the not too distant future. However, as laser systems with increasingly higher energies are developed, the difficulty of the laser safety problem increases proportionally, and presents unique safety challenges. The hazard distance for the direct beam can be in the order of thousands of miles, and radiation reflected from the target may also be hazardous over long distances. This paper details the Air Force Research Laboratory/Optical Radiation Branch (AFRL/HEDO) High-Energy Laser (HEL) safety program, which has been developed to support DOD HEL programs by providing critical capability and knowledge with respect to laser safety. The overall aim of the program is to develop and demonstrate technologies that permit safe testing, deployment and use of high-energy laser weapons. The program spans the range of applicable technologies, including evaluation of the biological effects of high-energy laser systems, development and validation of laser hazard assessment tools, and development of appropriate eye protection for those at risk.

Femtosecond pulse laser-oriented recording on dental prostheses: a trial introduction.

PubMed

Ichikawa, Tetsuo; Hayasaki, Yoshio; Fujita, Keiji; Nagao, Kan; Murata, Masayo; Kawano, Takanori; Chen, JianRong

2006-12-01

The purpose of this study was to evaluate the feasibility of using a femtosecond pulse laser processing technique to store information on a dental prosthesis. Commercially pure titanium plates were processed by a femtosecond pulse laser system. The processed surface structure was observed with a reflective illumination microscope, scanning electron microscope, and atomic force microscope. Processed area was an almost conical pit with a clear boundary. When laser pulse energy was 2 microJ, the diameter and depth were approximately 10microm and 0.2 microm respectively--whereby both increased with laser pulse energy. Further, depth of pit increased with laser pulse number without any thermal effect. This study showed that the femtosecond pulse processing system was capable of recording personal identification and optional additional information on a dental prosthesis.

Aircraft laser sensing of sound velocity in water - Brillouin scattering

NASA Technical Reports Server (NTRS)

Hickman, G. D.; Harding, John M.; Carnes, Michael; Pressman, AL; Kattawar, George W.; Fry, Edward S.

1991-01-01

A real-time data source for sound speed in the upper 100 m has been proposed for exploratory development. This data source is planned to be generated via a ship- or aircraft-mounted optical pulsed laser using the spontaneous Brillouin scattering technique. The system should be capable (from a single 10 ns 500 mJ pulse) of yielding range resolved sound speed profiles in water to depths of 75-100 m to an accuracy of 1 m/s. The 100 m profiles will provide the capability of rapidly monitoring the upper-ocean vertical structure. They will also provide an extensive, subsurface-data source for existing real-time, operational ocean nowcast/forecast systems.

Laser Imaging Video Camera Sees Through Fire, Fog, Smoke

NASA Technical Reports Server (NTRS)

2015-01-01

Under a series of SBIR contracts with Langley Research Center, inventor Richard Billmers refined a prototype for a laser imaging camera capable of seeing through fire, fog, smoke, and other obscurants. Now, Canton, Ohio-based Laser Imaging through Obscurants (LITO) Technologies Inc. is demonstrating the technology as a perimeter security system at Glenn Research Center and planning its future use in aviation, shipping, emergency response, and other fields.

The Long Range Reconnaissance and Observation System (LORROS) with the Kollsman, Inc. Model LH-40, Infrared (Erbium) Laser Rangefinder hazard analysis and safety assessment.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Augustoni, Arnold L.

A laser hazard analysis and safety assessment was performed for the LH-40 IR Laser Rangefinder based on the 2000 version of the American National Standard Institute's Standard Z136.1, for the Safe Use of Lasers and Z136.6, for the Safe Use of Lasers Outdoors. The LH-40 IR Laser is central to the Long Range Reconnaissance and Observation System (LORROS). The LORROS is being evaluated by the Department 4149 Group to determine its capability as a long-range assessment tool. The manufacture lists the laser rangefinder as 'eye safe' (Class 1 laser classified under the CDRH Compliance Guide for Laser Products and 21more » CFR 1040 Laser Product Performance Standard). It was necessary that SNL validate this prior to its use involving the general public. A formal laser hazard analysis is presented for the typical mode of operation.« less

The airborne laser ranging system, its capabilities and applications

NASA Technical Reports Server (NTRS)

Kahn, W. D.; Degnan, J. J.; Englar, T. S., Jr.

1982-01-01

The airborne laser ranging system is a multibeam short pulse laser ranging system on board an aircraft. It simultaneously measures the distances between the aircraft and six laser retroreflectors (targets) deployed on the Earth's surface. The system can interrogate over 100 targets distributed over an area of 25,000 sq, kilometers in a matter of hours. Potentially, a total of 1.3 million individual range measurements can be made in a six hour flight. The precision of these range measurements is approximately + or - 1 cm. These measurements are used in procedure which is basically an extension of trilateration techniques to derive the intersite vector between the laser ground targets. By repeating the estimation of the intersite vector, strain and strain rate errors can be estimated. These quantities are essential for crustal dynamic studies which include determination and monitoring of regional strain in the vicinity of active fault zones, land subsidence, and edifice building preceding volcanic eruptions.

Controlling Fringe Sensitivity of Electro-Optic Holography Systems Using Laser Diode Current Modulation

NASA Technical Reports Server (NTRS)

Bybee, Shannon J.

2001-01-01

Electro-Optic Holography (EOH) is a non-intrusive, laser-based, displacement measurement technique capable of static and dynamic displacement measurements. EOH is an optical interference technique in which fringe patterns that represent displacement contour maps are generated. At excessively large displacements the fringe density may be so great that individual fringes are not resolvable using typical EOH techniques. This thesis focuses on the development and implementation of a method for controlling the sensitivity of the EOH system. This method is known as Frequency Translated Electro-Optic Holography (FTEOH). It was determined that by modulating the current source of the laser diode at integer multiples of the object vibration, the fringe pattern is governed by higher order Bessel function of the first kind and the number of fringes that represent a given displacement can be controlled. The reduction of fringes is theoretically unlimited but physically limited by the frequency bandwidth of the signal generator, providing modulation to the laser diode. Although this research technique has been verified theoretically and experimentally in this thesis, due to the current laser diode capabilities it is a tedious and time consuming process to acquire data using the FTEOH technique.

Three-dimensional tracking and imaging laser scanner for space operations

NASA Astrophysics Data System (ADS)

Laurin, Denis G.; Beraldin, J. A.; Blais, Francois; Rioux, Marc; Cournoyer, Luc

1999-05-01

This paper presents the development of a laser range scanner (LARS) as a three-dimensional sensor for space applications. The scanner is a versatile system capable of doing surface imaging, target ranging and tracking. It is capable of short range (0.5 m to 20 m) and long range (20 m to 10 km) sensing using triangulation and time-of-flight (TOF) methods respectively. At short range (1 m), the resolution is sub-millimeter and drops gradually with distance (2 cm at 10 m). For long range, the TOF provides a constant resolution of plus or minus 3 cm, independent of range. The LARS could complement the existing Canadian Space Vision System (CSVS) for robotic manipulation. As an active vision system, the LARS is immune to sunlight and adverse lighting; this is a major advantage over the CSVS, as outlined in this paper. The LARS could also replace existing radar systems used for rendezvous and docking. There are clear advantages of an optical system over a microwave radar in terms of size, mass, power and precision. Equipped with two high-speed galvanometers, the laser can be steered to address any point in a 30 degree X 30 degree field of view. The scanning can be continuous (raster scan, Lissajous) or direct (random). This gives the scanner the ability to register high-resolution 3D images of range and intensity (up to 4000 X 4000 pixels) and to perform point target tracking as well as object recognition and geometrical tracking. The imaging capability of the scanner using an eye-safe laser is demonstrated. An efficient fiber laser delivers 60 mW of CW or 3 (mu) J pulses at 20 kHz for TOF operation. Implementation of search and track of multiple targets is also demonstrated. For a single target, refresh rates up to 137 Hz is possible. Considerations for space qualification of the scanner are discussed. Typical space operations, such as docking, object attitude tracking, and inspections are described.

Overview of laser systems for the Orion facility at the AWE.

PubMed

Hopps, Nicholas; Danson, Colin; Duffield, Stuart; Egan, David; Elsmere, Stephen; Girling, Mark; Harvey, Ewan; Hillier, David; Norman, Michael; Parker, Stefan; Treadwell, Paul; Winter, David; Bett, Thomas

2013-05-20

The commissioning of the Orion laser facility at the Atomic Weapons Establishment (AWE) in the UK has recently been completed. The facility is a twelve beam Nd:glass-based system for studying high energy density physics. It consists of ten frequency-tripled beam-lines operating with nanosecond pulses, synchronized with two beam-lines with subpicosecond pulses, each capable of delivering 500 J to target. One of the short pulse beams has the option of frequency doubling, at reduced aperture, to yield up to 100 J at 527 nm in a subpicosecond pulse with high temporal contrast. An extensive array of target diagnostics is provided. This article describes the laser design and commissioning and presents key performance data of the facility's laser systems.

Picometer-resolution dual-comb spectroscopy with a free-running fiber laser.

PubMed

Zhao, Xin; Hu, Guoqing; Zhao, Bofeng; Li, Cui; Pan, Yingling; Liu, Ya; Yasui, Takeshi; Zheng, Zheng

2016-09-19

Dual-comb spectroscopy holds the promise as real-time, high-resolution spectroscopy tools. However, in its conventional schemes, the stringent requirement on the coherence between two lasers requires sophisticated control systems. By replacing control electronics with an all-optical dual-comb lasing scheme, a simplified dual-comb spectroscopy scheme is demonstrated using one dual-wavelength, passively mode-locked fiber laser. Pulses with a intracavity-dispersion-determined repetition-frequency difference are shown to have good mutual coherence and stability. Capability to resolve the comb teeth and a picometer-wide optical spectral resolution are demonstrated using a simple data acquisition system. Energy-efficient, free-running fiber lasers with a small comb-tooth-spacing could enable low-cost dual-comb systems.

CO2 DIAL system: construction, measurements, and future development

NASA Astrophysics Data System (ADS)

Vicenik, Jiri

1999-07-01

A miniature CO2 DIAL system has been constructed. Dimension of the system are 500 X 450 X 240 mm, its mass is only 28 kg. The system consists of two tunable TEA CO2 lasers, receiving optics, IR detector, signal processing electronics and single chip microcomputer with display. The lasers are tuned manually by means of micrometric screw and are capable to generate pulses on more than 50 CO2 laser lines. The output energy is 50 mJ. The system was tested using various toxic gases and simulants, mostly at range 300 m, most of the measurements were done using pyrodetector in the receiver. The system shows good sensitivity, but it exhibits substantial instability of zero concentration. In the next stage the work will be concentrated on use of high-sensitivity MCT detector in the receiver and implementation of automatic tuning of lasers to the system.

Cerebral blood oxygenation measurements in neonates with optoacoustic technique

NASA Astrophysics Data System (ADS)

Herrmann, Stephen; Petrov, Irene Y.; Petrov, Yuriy; Richardson, C. Joan; Fonseca, Rafael A.; Prough, Donald S.; Esenaliev, Rinat O.

2017-03-01

Cerebral hypoxia is a major contributor to neonatal/infant mortality and morbidity including severe neurological complications such as mental retardation, cerebral palsy, motor impairment, and epilepsy. Currently, no technology is capable of accurate monitoring of neonatal cerebral oxygenation. We proposed to use optoacoustics for this application by probing the superior sagittal sinus (SSS), a large central cerebral vein. We developed and built a multi-wavelength, optical parametric oscillator (OPO) and laser diode optoacoustic systems for measurement of SSS blood oxygenation in the reflection mode through open anterior or posterior fontanelles and in the transmission mode through the skull in the occipital area. In this paper we present results of initial tests of the laser diode system for neonatal cerebral oxygenation measurements. First, the system was tested in phantoms simulating neonatal SSS. Then, using the data obtained in the phantoms, we optimized the system's hardware and software and tested it in neonates admitted in the Neonatal Intensive Care Unit. The laser diode system was capable of detecting SSS signals in the reflection mode through the open anterior and posterior fontanelles as well as in the transmission mode through the skull with high signal-to-noise ratio. Using the signals measured at different wavelengths and algorithms developed for oxygenation measurements, the laser diode system provided real-time, continuous oxygenation monitoring with high precision at all these locations.

The eyes of LITENING

NASA Astrophysics Data System (ADS)

Moser, Eric K.

2016-05-01

LITENING is an airborne system-of-systems providing long-range imaging, targeting, situational awareness, target tracking, weapon guidance, and damage assessment, incorporating a laser designator and laser range finders, as well as non-thermal and thermal imaging systems, with multi-sensor boresight. Robust operation is at a premium, and subsystems are partitioned to modular, swappable line-replaceable-units (LRUs) and shop-replaceable-units (SRUs). This presentation will explore design concepts for sensing, data storage, and presentation of imagery associated with the LITENING targeting pod. The "eyes" of LITENING are the electro-optic sensors. Since the initial LITENING II introduction to the US market in the late 90s, as the program has evolved and matured, a series of spiral functional improvements and sensor upgrades have been incorporated. These include laser-illuminated imaging, and more recently, color sensing. While aircraft displays are outside of the LITENING system, updates to the available viewing modules have also driven change, and resulted in increasingly effective ways of utilizing the targeting system. One of the latest LITENING spiral upgrades adds a new capability to display and capture visible-band color imagery, using new sensors. This is an augmentation to the system's existing capabilities, which operate over a growing set of visible and invisible colors, infrared bands, and laser line wavelengths. A COTS visible-band camera solution using a CMOS sensor has been adapted to meet the particular needs associated with the airborne targeting use case.

True color blood flow imaging using a high-speed laser photography system

NASA Astrophysics Data System (ADS)

Liu, Chien-Sheng; Lin, Cheng-Hsien; Sun, Yung-Nien; Ho, Chung-Liang; Hsu, Chung-Chi

2012-10-01

Physiological changes in the retinal vasculature are commonly indicative of such disorders as diabetic retinopathy, glaucoma, and age-related macular degeneration. Thus, various methods have been developed for noninvasive clinical evaluation of ocular hemodynamics. However, to the best of our knowledge, current ophthalmic instruments do not provide a true color blood flow imaging capability. Accordingly, we propose a new method for the true color imaging of blood flow using a high-speed pulsed laser photography system. In the proposed approach, monochromatic images of the blood flow are acquired using a system of three cameras and three color lasers (red, green, and blue). A high-quality true color image of the blood flow is obtained by assembling the monochromatic images by means of image realignment and color calibration processes. The effectiveness of the proposed approach is demonstrated by imaging the flow of mouse blood within a microfluidic channel device. The experimental results confirm the proposed system provides a high-quality true color blood flow imaging capability, and therefore has potential for noninvasive clinical evaluation of ocular hemodynamics.

Testing and integrating the laser system of ARGOS: the ground layer adaptive optics for LBT

NASA Astrophysics Data System (ADS)

Loose, C.; Rabien, S.; Barl, L.; Borelli, J.; Deysenroth, M.; Gaessler, W.; Gemperlein, H.; Honsberg, M.; Kulas, M.; Lederer, R.; Raab, W.; Rahmer, G.; Ziegleder, J.

2012-07-01

The Laser Guide Star facility ARGOS will provide Ground Layer Adaptive Optics to the Large Binocular Telescope (LBT). The system operates three pulsed laser beacons above each of the two primary mirrors, which are Rayleigh scattered in 12km height. This enables correction over a wide field of view, using the adaptive secondary mirror of the LBT. The ARGOS laser system is designed around commercially available, pulsed Nd:YAG lasers working at 532 nm. In preparation for a successful commissioning, it is important to ascertain that the specifications are met for every component of the laser system. The testing of assembled, optical subsystems is likewise necessary. In particular it is required to confirm a high output power, beam quality and pulse stability of the beacons. In a second step, the integrated laser system along with its electronic cabinets are installed on a telescope simulator. This unit is capable of carrying the whole assembly and can be tilted to imitate working conditions at the LBT. It allows alignment and functionality testing of the entire system, ensuring that flexure compensation and system diagnosis work properly in different orientations.

Laser Angioplasty

NASA Technical Reports Server (NTRS)

1990-01-01

The principal method of dealing with coronary artery blockage is bypass surgery. A non-surgical alternative available to some patients is balloon angioplasty. For several years, medical researchers have been exploring another alternative that would help a wider circle of patients than the balloon treatment and entail less risk than bypass surgery. A research group is on the verge of an exciting development: laser angioplasty with a 'cool' type of laser, called an excimer laser, that does not damage blood vessel walls and offers non-surgical cleansing of clogged arteries with extraordinary precision. The system is the Dymer 200+ Excimer Laser Angioplasty System, developed by Advanced Intraventional Systems. Used in human clinical tests since 1987, the system is the first fully integrated 'cool' laser capable of generating the requisite laser energy and delivering the energy to target arteries. Thirteen research hospitals in the U.S. have purchased Dymer 200+ systems and used them in clinical trials in 121 peripheral and 555 coronary artery cases. The success rate in opening blocked coronary arteries is 85 percent, with fewer complications than in balloon angioplasty. Food and Drug Administration approval for the system is hoped for in the latter part of 1990. * Advanced Intraventional Systems became Spectranetics in 1994 and discontinued the product.

Laser designator protection filter for see-spot thermal imaging systems

NASA Astrophysics Data System (ADS)

Donval, Ariela; Fisher, Tali; Lipman, Ofir; Oron, Moshe

2012-06-01

In some cases the FLIR has an open window in the 1.06 micrometer wavelength range; this capability is called 'see spot' and allows seeing a laser designator spot using the FLIR. A problem arises when the returned laser energy is too high for the camera sensitivity, and therefore can cause damage to the sensor. We propose a non-linear, solid-state dynamic filter solution protecting from damage in a passive way. Our filter blocks the transmission, only if the power exceeds a certain threshold as opposed to spectral filters that block a certain wavelength permanently. In this paper we introduce the Wideband Laser Protection Filter (WPF) solution for thermal imaging systems possessing the ability to see the laser spot.

Remote imaging laser-induced breakdown spectroscopy and laser-induced fluorescence spectroscopy using nanosecond pulses from a mobile lidar system.

PubMed

Grönlund, Rasmus; Lundqvist, Mats; Svanberg, Sune

2006-08-01

A mobile lidar system was used in remote imaging laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF) experiments. Also, computer-controlled remote ablation of a chosen area was demonstrated, relevant to cleaning of cultural heritage items. Nanosecond frequency-tripled Nd:YAG laser pulses at 355 nm were employed in experiments with a stand-off distance of 60 meters using pulse energies of up to 170 mJ. By coaxial transmission and common folding of the transmission and reception optical paths using a large computer-controlled mirror, full elemental imaging capability was achieved on composite targets. Different spectral identification algorithms were compared in producing thematic data based on plasma or fluorescence light.

Combined hostile fire and optics detection

NASA Astrophysics Data System (ADS)

Brännlund, Carl; Tidström, Jonas; Henriksson, Markus; Sjöqvist, Lars

2013-10-01

Snipers and other optically guided weapon systems are serious threats in military operations. We have studied a SWIR (Short Wave Infrared) camera-based system with capability to detect and locate snipers both before and after shot over a large field-of-view. The high frame rate SWIR-camera allows resolution of the temporal profile of muzzle flashes which is the infrared signature associated with the ejection of the bullet from the rifle. The capability to detect and discriminate sniper muzzle flashes with this system has been verified by FOI in earlier studies. In this work we have extended the system by adding a laser channel for optics detection. A laser diode with slit-shaped beam profile is scanned over the camera field-of-view to detect retro reflection from optical sights. The optics detection system has been tested at various distances up to 1.15 km showing the feasibility to detect rifle scopes in full daylight. The high speed camera gives the possibility to discriminate false alarms by analyzing the temporal data. The intensity variation, caused by atmospheric turbulence, enables discrimination of small sights from larger reflectors due to aperture averaging, although the targets only cover a single pixel. It is shown that optics detection can be integrated in combination with muzzle flash detection by adding a scanning rectangular laser slit. The overall optics detection capability by continuous surveillance of a relatively large field-of-view looks promising. This type of multifunctional system may become an important tool to detect snipers before and after shot.

Qualification testing of fiber-based laser transmitters and on-orbit validation of a commercial laser system

NASA Astrophysics Data System (ADS)

Wright, M. W.; Wilkerson, M. W.; Tang, R. R.

2017-11-01

Qualification testing of fiber based laser transmitters is required for NASA's Deep Space Optical Communications program to mature the technology for space applications. In the absence of fully space qualified systems, commercial systems have been investigated in order to demonstrate the robustness of the technology. To this end, a 2.5 W fiber based laser source was developed as the transmitter for an optical communications experiment flown aboard the ISS as a part of a technology demonstration mission. The low cost system leveraged Mil Standard design principles and Telcordia certified components to the extent possible and was operated in a pressure vessel with active cooling. The laser was capable of high rate modulation but was limited by the mission requirements to 50 Mbps for downlinking stored video from the OPALS payload, externally mounted on the ISS. Environmental testing and space qualification of this unit will be discussed along with plans for a fully space qualified laser transmitter.

Computer simulation of a multiple-aperture coherent laser radar

NASA Astrophysics Data System (ADS)

Gamble, Kevin J.; Weeks, Arthur R.

1996-06-01

This paper presents the construction of a 2D multiple aperture coherent laser radar simulation that is capable of including the effects of the time evolution of speckle on the laser radar output. Every portion of a laser radar system is modeled in software, including quarter and half wave plates, beamsplitters (polarizing and non-polarizing), the detector, the laser source, and all necessary lenses. Free space propagation is implemented using the Rayleigh- Sommerfeld integral for both orthogonal polarizations. Atmospheric turbulence is also included in the simulation and is modeled using time correlated Kolmogorov phase screens. The simulation itself can be configured to simulate both monostatic and bistatic systems. The simulation allows the user to specify component level parameters such as extinction ratios for polarizing beam splitters, detector sizes and shapes. orientation of the slow axis for quarter/half wave plates and other components used in the system. This is useful from a standpoint of being a tool in the design of a multiple aperture laser radar system.

An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography

PubMed Central

Eom, Jonghyun; Shin, Jun Geun; Park, Soongho; Rim, Sunghwan; Lee, Byeong Ha

2016-01-01

We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT) and optical coherence tomography (OCT). The PAT remotely measures photoacoustic (PA) signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF) and a large-core multimode fiber (MMF). The compact and robust common probe is capable of obtaining both the PA and the OCT signals at the same position without any physical contact. Additionally, the MMF of the probe delivers the short pulses of a Nd:YAG laser to efficiently excite the PA signals. We experimentally demonstrate the feasibility of the proposed dual-modal system with a phantom made of a fishing line and a black polyethylene terephthalate fiber in a tissue mimicking solution. The all-fiber-optic system, capable of providing complementary information about absorption and scattering, has a promising potential in minimally invasive and endoscopic imaging. PMID:27213392

Evaluation of a high framerate multi-exposure laser speckle contrast imaging setup

NASA Astrophysics Data System (ADS)

Hultman, Martin; Fredriksson, Ingemar; Strömberg, Tomas; Larsson, Marcus

2018-02-01

We present a first evaluation of a new multi-exposure laser speckle contrast imaging (MELSCI) system for assessing spatial variations in the microcirculatory perfusion. The MELSCI system is based on a 1000 frames per second 1-megapixel camera connected to a field programmable gate arrays (FPGA) capable of producing MELSCI data in realtime. The imaging system is evaluated against a single point laser Doppler flowmetry (LDF) system during occlusionrelease provocations of the arm in five subjects. Perfusion is calculated from MELSCI data using current state-of-the-art inverse models. The analysis displayed a good agreement between measured and modeled data, with an average error below 6%. This strongly indicates that the applied model is capable of accurately describing the MELSCI data and that the acquired data is of high quality. Comparing readings from the occlusion-release provocation showed that the MELSCI perfusion was significantly correlated (R=0.83) to the single point LDF perfusion, clearly outperforming perfusion estimations based on a single exposure time. We conclude that the MELSCI system provides blood flow images of enhanced quality, taking us one step closer to a system that accurately can monitor dynamic changes in skin perfusion over a large area in real-time.

An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography.

PubMed

Eom, Jonghyun; Shin, Jun Geun; Park, Soongho; Rim, Sunghwan; Lee, Byeong Ha

2016-05-20

We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT) and optical coherence tomography (OCT). The PAT remotely measures photoacoustic (PA) signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF) and a large-core multimode fiber (MMF). The compact and robust common probe is capable of obtaining both the PA and the OCT signals at the same position without any physical contact. Additionally, the MMF of the probe delivers the short pulses of a Nd:YAG laser to efficiently excite the PA signals. We experimentally demonstrate the feasibility of the proposed dual-modal system with a phantom made of a fishing line and a black polyethylene terephthalate fiber in a tissue mimicking solution. The all-fiber-optic system, capable of providing complementary information about absorption and scattering, has a promising potential in minimally invasive and endoscopic imaging.

Fuel spray data with LDV. [solar laser morphokinetomer capabilities in combustion research

NASA Technical Reports Server (NTRS)

Rohy, D. A.; Meier, J. G.

1979-01-01

Droplet size and two component velocities in the severe environment of an operating gas turbine combustor system can be measured simultaneously using the solar laser morphokinetomer (SLM) which incorporates the following capabilities: (1) measurement of a true two-dimensional velocity vector with a range of + or - (0.01-200 m/sec); (2) measurement of particle size (range 5 to 300 micron m) simultaneously with the measurement of velocity; (3) specification of probe volume position coordinates with a high degree of accuracy (+ or - 0.5 mm); (4) immediate on-line data checks; and (5) rapid computer storage of acquired data. The optical system of the SLM incorporates an ultrasonic beam splitter to allow the measurement of a two-dimensional velocity vector simultaneously with particle size. A microprocessor with a limited storage capability permits immediate analysis of test data in the test cell.

Lasers for bio-optics

NASA Astrophysics Data System (ADS)

Sona, Alberto

1992-03-01

Lasers are being increasingly used in bioptics and in life sciences in general, especially for medical applications for therapy and diagnostics. Lasers are also broadly used in environment sciences to monitor atmospheric parameters and concentrations of molecular species of natural origin or coming from human activities such as the various kind of pollutants. The peculiar features of lasers exploited in these areas are mainly the capability of developing an action or performing a measurement without physical contact with the target and, if required, from a remote position with the assistance of suitable beam delivery systems such as telescopes, microscopes, or optical fibers. These features are directly related to the space and time coherence of the laser light and to the energy storage capability of the laser material which allow an extremely effective concentration of the beam energy in space, direction frequency, or time. A short description of the principle of operation and relevant properties of lasers are given and the most significant properties of the laser emission are briefly reviewed. Lasers for medical applications (mainly for therapy) will be mentioned, pointing out the specific property exploited for the various applications. Finally, examples of laser applications to the environmental sciences will be reported. A summary of the properties exploited in the various bio-optical applications is shown.

A simplified hardwood log-sawing program for three-dimensional profile data

Treesearch

R. Edward Thomas

2011-01-01

Current laser scanning systems in sawmills collect low-resolution three-dimensional (3D) profiles of logs. However, these scanners are capable of much more. As a demonstration, the U.S. Forest Service, Forestry Sciences Laboratory in Princeton, WV, constructed a 3D laser log scanner using off -the-shelf industrial scanning components.

Data acquisition and control system with a programmable logic controller (PLC) for a pulsed chemical oxygen-iodine laser

NASA Astrophysics Data System (ADS)

Yu, Haijun; Li, Guofu; Duo, Liping; Jin, Yuqi; Wang, Jian; Sang, Fengting; Kang, Yuanfu; Li, Liucheng; Wang, Yuanhu; Tang, Shukai; Yu, Hongliang

2015-02-01

A user-friendly data acquisition and control system (DACS) for a pulsed chemical oxygen -iodine laser (PCOIL) has been developed. It is implemented by an industrial control computer，a PLC, and a distributed input/output (I/O) module, as well as the valve and transmitter. The system is capable of handling 200 analogue/digital channels for performing various operations such as on-line acquisition, display, safety measures and control of various valves. These operations are controlled either by control switches configured on a PC while not running or by a pre-determined sequence or timings during the run. The system is capable of real-time acquisition and on-line estimation of important diagnostic parameters for optimization of a PCOIL. The DACS system has been programmed using software programmable logic controller (PLC). Using this DACS, more than 200 runs were given performed successfully.

Laser applications and system considerations in ocular imaging

PubMed Central

Elsner, Ann E.; Muller, Matthew S.

2009-01-01

We review laser applications for primarily in vivo ocular imaging techniques, describing their constraints based on biological tissue properties, safety, and the performance of the imaging system. We discuss the need for cost effective sources with practical wavelength tuning capabilities for spectral studies. Techniques to probe the pathological changes of layers beneath the highly scattering retina and diagnose the onset of various eye diseases are described. The recent development of several optical coherence tomography based systems for functional ocular imaging is reviewed, as well as linear and nonlinear ocular imaging techniques performed with ultrafast lasers, emphasizing recent source developments and methods to enhance imaging contrast. PMID:21052482

Experimental demonstration of a retro-reflective laser communication link on a mobile platform

NASA Astrophysics Data System (ADS)

Nikulin, Vladimir V.; Malowicki, John E.; Khandekar, Rahul M.; Skormin, Victor A.; Legare, David J.

2010-02-01

Successful pointing, acquisition, and tracking (PAT) are crucial for the implementation of laser communication links between ground and aerial vehicles. This technology has advantages over the traditional radio frequency communication, thus justifying the research efforts presented in this paper. The authors have been successful in the development of a high precision, agile, digitally controlled two-degree-of-freedom electromechanical system for positioning of optical instruments, cameras, telescopes, and communication lasers. The centerpiece of this system is a robotic manipulator capable of singularity-free operation throughout the full hemisphere range of yaw/pitch motion. The availability of efficient two-degree-of-freedom positioning facilitated the development of an optical platform stabilization system capable of rejecting resident vibrations with the angular and frequency range consistent with those caused by a ground vehicle moving on a rough terrain. This technology is being utilized for the development of a duplex mobile PAT system demonstrator that would provide valuable feedback for the development of practical laser communication systems intended for fleets of moving ground, and possibly aerial, vehicles. In this paper, a tracking system providing optical connectivity between stationary and mobile ground platforms is described. It utilizes mechanical manipulator to perform optical platform stabilization and initial beam positioning, and optical tracking for maintaining the line-of-sight communication. Particular system components and the challenges of their integration are described. The results of field testing of the resultant system under practical conditions are presented.

Guiding of laser pulses in plasma waveguides created by linearly-polarized femtosecond laser pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemos, N.; Cardoso, L.; Geada, J.

We experimentally demonstrate that plasma waveguides produced with ultra-short laser pulses (sub-picosecond) in gas jets are capable of guiding high intensity laser pulses. This scheme has the unique ability of guiding a high-intensity laser pulse in a plasma waveguide created by the same laser system in the very simple and stable experimental setup. A hot plasma column was created by a femtosecond class laser that expands into an on-axis parabolic low density profile suitable to act as a waveguide for high intensity laser beams. We have successfully guided ~10 15 W cm -2 laser pulses in a 8 mm longmore » hydrogen plasma waveguide with a 35% guiding efficiency.« less

Guiding of laser pulses in plasma waveguides created by linearly-polarized femtosecond laser pulses

DOE PAGES

Lemos, N.; Cardoso, L.; Geada, J.; ...

2018-02-16

We experimentally demonstrate that plasma waveguides produced with ultra-short laser pulses (sub-picosecond) in gas jets are capable of guiding high intensity laser pulses. This scheme has the unique ability of guiding a high-intensity laser pulse in a plasma waveguide created by the same laser system in the very simple and stable experimental setup. A hot plasma column was created by a femtosecond class laser that expands into an on-axis parabolic low density profile suitable to act as a waveguide for high intensity laser beams. We have successfully guided ~10 15 W cm -2 laser pulses in a 8 mm longmore » hydrogen plasma waveguide with a 35% guiding efficiency.« less

Characterization of a Hybrid Optical Microscopy/Laser Ablation Liquid Vortex Capture/Electrospray Ionization System for Mass Spectrometry Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cahill, John F.; Kertesz, Vilmos; Van Berkel, Gary J.

Herein, a commercial optical microscope, laser microdissection instrument was coupled with an electrospray ionization mass spectrometer via a low profile liquid vortex capture probe to yield a hybrid optical microscopy/mass spectrometry imaging system. The instrument has bright-field and fluorescence microscopy capabilities in addition to a highly focused UV laser beam that is utilized for laser ablation of samples. With this system, material laser ablated from a sample using the microscope was caught by a liquid vortex capture probe and transported in solution for analysis by electrospray ionization mass spectrometry. Both lane scanning and spot sampling mass spectral imaging modes weremore » used. The smallest area the system was able to ablate was ~0.544 μm × ~0.544 μm, achieved by oversampling of the smallest laser ablation spot size that could be obtained (~1.9 μm). With use of a model photoresist surface, known features as small as ~1.5 μm were resolved. The capabilities of the system with real world samples were demonstrated first with a blended polymer thin film containing poly(2-vinylpyridine) and poly(N-vinylcarbazole). Using spot sampling imaging, sub-micrometer sized features (0.62, 0.86, and 0.98 μm) visible by optical microscopy were clearly distinguished in the mass spectral images. A second real world example showed the imaging of trace amounts of cocaine in mouse brain thin tissue sections. Lastly, with use of a lane scanning mode with ~6 μm × ~6 μm data pixels, features in the tissue as small as 15 μm in size could be distinguished in both the mass spectral and optical images.« less

Characterization of a Hybrid Optical Microscopy/Laser Ablation Liquid Vortex Capture/Electrospray Ionization System for Mass Spectrometry Imaging

DOE PAGES

Cahill, John F.; Kertesz, Vilmos; Van Berkel, Gary J.

2015-10-22

Herein, a commercial optical microscope, laser microdissection instrument was coupled with an electrospray ionization mass spectrometer via a low profile liquid vortex capture probe to yield a hybrid optical microscopy/mass spectrometry imaging system. The instrument has bright-field and fluorescence microscopy capabilities in addition to a highly focused UV laser beam that is utilized for laser ablation of samples. With this system, material laser ablated from a sample using the microscope was caught by a liquid vortex capture probe and transported in solution for analysis by electrospray ionization mass spectrometry. Both lane scanning and spot sampling mass spectral imaging modes weremore » used. The smallest area the system was able to ablate was ~0.544 μm × ~0.544 μm, achieved by oversampling of the smallest laser ablation spot size that could be obtained (~1.9 μm). With use of a model photoresist surface, known features as small as ~1.5 μm were resolved. The capabilities of the system with real world samples were demonstrated first with a blended polymer thin film containing poly(2-vinylpyridine) and poly(N-vinylcarbazole). Using spot sampling imaging, sub-micrometer sized features (0.62, 0.86, and 0.98 μm) visible by optical microscopy were clearly distinguished in the mass spectral images. A second real world example showed the imaging of trace amounts of cocaine in mouse brain thin tissue sections. Lastly, with use of a lane scanning mode with ~6 μm × ~6 μm data pixels, features in the tissue as small as 15 μm in size could be distinguished in both the mass spectral and optical images.« less

Ion beam production and study of radioactive isotopes with the laser ion source at ISOLDE

NASA Astrophysics Data System (ADS)

Fedosseev, Valentin; Chrysalidis, Katerina; Day Goodacre, Thomas; Marsh, Bruce; Rothe, Sebastian; Seiffert, Christoph; Wendt, Klaus

2017-08-01

At ISOLDE the majority of radioactive ion beams are produced using the resonance ionization laser ion source (RILIS). This ion source is based on resonant excitation of atomic transitions by wavelength tunable laser radiation. Since its installation at the ISOLDE facility in 1994, the RILIS laser setup has been developed into a versatile remotely operated laser system comprising state-of-the-art solid state and dye lasers capable of generating multiple high quality laser beams at any wavelength in the range of 210-950 nm. A continuous programme of atomic ionization scheme development at CERN and at other laboratories has gradually increased the number of RILIS-ionized elements. At present, isotopes of 40 different elements have been selectively laser-ionized by the ISOLDE RILIS. Studies related to the optimization of the laser-atom interaction environment have yielded new laser ion source types: the laser ion source and trap and the versatile arc discharge and laser ion source. Depending on the specific experimental requirements for beam purity or versatility to switch between different ionization mechanisms, these may offer a favourable alternative to the standard hot metal cavity configuration. In addition to its main purpose of ion beam production, the RILIS is used for laser spectroscopy of radioisotopes. In an ongoing experimental campaign the isotope shifts and hyperfine structure of long isotopic chains have been measured by the extremely sensitive in-source laser spectroscopy method. The studies performed in the lead region were focused on nuclear deformation and shape coexistence effects around the closed proton shell Z = 82. The paper describes the functional principles of the RILIS, the current status of the laser system and demonstrated capabilities for the production of different ion beams including the high-resolution studies of short-lived isotopes and other applications of RILIS lasers for ISOLDE experiments. This article belongs to the Focus on Exotic Beams at ISOLDE: A Laboratory Portrait special issue.

Next generation laser-based standoff spectroscopy techniques for Mars exploration.

PubMed

Gasda, Patrick J; Acosta-Maeda, Tayro E; Lucey, Paul G; Misra, Anupam K; Sharma, Shiv K; Taylor, G Jeffrey

2015-01-01

In the recent Mars 2020 Rover Science Definition Team Report, the National Aeronautics and Space Administration (NASA) has sought the capability to detect and identify elements, minerals, and most importantly, biosignatures, at fine scales for the preparation of a retrievable cache of samples. The current Mars rover, the Mars Science Laboratory Curiosity, has a remote laser-induced breakdown spectroscopy (LIBS) instrument, a type of quantitative elemental analysis, called the Chemistry Camera (ChemCam) that has shown that laser-induced spectroscopy instruments are not only feasible for space exploration, but are reliable and complementary to traditional elemental analysis instruments such as the Alpha Particle X-Ray Spectrometer. The superb track record of ChemCam has paved the way for other laser-induced spectroscopy instruments, such as Raman and fluorescence spectroscopy. We have developed a prototype remote LIBS-Raman-fluorescence instrument, Q-switched laser-induced time-resolved spectroscopy (QuaLITy), which is approximately 70 000 times more efficient at recording signals than a commercially available LIBS instrument. The increase in detection limits and sensitivity is due to our development of a directly coupled system, the use of an intensified charge-coupled device image detector, and a pulsed laser that allows for time-resolved measurements. We compare the LIBS capabilities of our system with an Ocean Optics spectrometer instrument at 7 m and 5 m distance. An increase in signal-to-noise ratio of at least an order of magnitude allows for greater quantitative analysis of the elements in a LIBS spectrum with 200-300 μm spatial resolution at 7 m, a Raman instrument capable of 1 mm spatial resolution at 3 m, and bioorganic fluorescence detection at longer distances. Thus, the new QuaLITy instrument fulfills all of the NASA expectations for proposed instruments.

High-performance two-axis gimbal system for free space laser communications onboard unmanned aircraft systems

NASA Astrophysics Data System (ADS)

Locke, Michael; Czarnomski, Mariusz; Qadir, Ashraf; Setness, Brock; Baer, Nicolai; Meyer, Jennifer; Semke, William H.

2011-03-01

A custom designed and manufactured gimbal with a wide field-of-view and fast response time is developed. This enhanced custom design is a 24 volt system with integrated motor controllers and drivers which offers a full 180o fieldof- view in both azimuth and elevation; this provides a more continuous tracking capability as well as increased velocities of up to 479° per second. The addition of active high-frequency vibration control, to complement the passive vibration isolation system, is also in development. The ultimate goal of this research is to achieve affordable, reliable, and secure air-to-air laser communications between two separate remotely piloted aircraft. As a proof-of-concept, the practical implementation of an air-to-ground laserbased video communications payload system flown by a small Unmanned Aerial Vehicle (UAV) will be demonstrated. A numerical tracking algorithm has been written, tested, and used to aim the airborne laser transmitter at a stationary ground-based receiver with known GPS coordinates; however, further refinement of the tracking capabilities is dependent on an improved gimbal design for precision pointing of the airborne laser transmitter. The current gimbal pointing system is a two-axis, commercial-off-the-shelf component, which is limited in both range and velocity. The current design is capable of 360o of pan and 78o of tilt at a velocity of 60o per second. The control algorithm used for aiming the gimbal is executed on a PC-104 format embedded computer onboard the payload to accurately track a stationary ground-based receiver. This algorithm autonomously calculates a line-of-sight vector in real-time by using the UAV autopilot's Differential Global Positioning System (DGPS) which provides latitude, longitude, and altitude and Inertial Measurement Unit (IMU) which provides the roll, pitch, and yaw data, along with the known Global Positioning System (GPS) location of the ground-based photodiode array receiver.

Airborne lidar wind detection at 2 μm

NASA Astrophysics Data System (ADS)

Targ, Russell; Hawley, James G.; Steakley, Bruce C.; Ames, Lawrence L.; Robinson, Paul A.

1995-06-01

NASA and the FAA have expressed interest in laser radar's capabilities to detect wind profiles at altitude. A number of programs have been addressing the technical feasibility and utility of laser radar atmospheric backscatter data to determine wind profiles and wind hazards for aircraft guidance and navigation. In addition, the U.S. Air Force is investigating the use of airborne lidar to achieve precision air drop capability, and to increase the accuracy of the AC- 130 gunship and the B-52 bomber by measuring the wind field from the aircraft to the ground. There are emerging capabilities of airborne laser radar to measure wind velocities and detect turbulence and other atmospheric disturbances out in front of an aircraft in real time. The measurement of these parameters can significantly increase fuel efficiency, flight safety, airframe lifetime, and terminal area capacity for new and existing aircraft. This is achieved through wind velocity detection, turbulence avoidance, active control utilization to alleviate gust loading, and detection of wingtip wake vortices produced by landing aircraft. This paper presents the first flight test results of an all solid-state 2-micrometers laser radar system measuring the wind field profile 1 to 2 km in front of an aircraft in real time. We find 0.7-m/s wind measurement accuracy for the system which is configured in a rugged, light weight, high- performance ARINC package.

Characterization of a novel miniaturized burst-mode infrared laser system for IR-MALDESI mass spectrometry imaging.

PubMed

Ekelöf, Måns; Manni, Jeffrey; Nazari, Milad; Bokhart, Mark; Muddiman, David C

2018-03-01

Laser systems are widely used in mass spectrometry as sample probes and ionization sources. Mid-infrared lasers are particularly suitable for analysis of high water content samples such as animal and plant tissues, using water as a resonantly excited sacrificial matrix. Commercially available mid-IR lasers have historically been bulky and expensive due to cooling requirements. This work presents a novel air-cooled miniature mid-IR laser with adjustable burst-mode output and details an evaluation of its performance for mass spectrometry imaging. The miniature laser was found capable of generating sufficient energy for complete ablation of animal tissue in the context of an IR-MALDESI experiment with exogenously added ice matrix, yielding several hundred confident metabolite identifications. Graphical abstract The use of a novel miniature 2.94 μm burst-mode laser in IR-MALDESI allows for rapid and sensitive mass spectrometry imaging of a whole mouse.

Cutaneous resurfacing with CO2 and erbium: YAG lasers: preoperative, intraoperative, and postoperative considerations.

PubMed

Alster, T S

1999-02-01

The development and integration of pulsed and scanned CO2 and erbium:YAG laser systems into mainstream surgical practice over the past years has revolutionized cutaneous resurfacing. These lasers are capable of delivering to skin high peak fluences to effect controlled tissue vaporization, while leaving an acceptably narrow zone of residual thermal damage. The inherent technological differences that exist between the two distant laser systems in terms of ablation depths, degree of thermal coagulation, and postoperative side-effects and complications guide patient selection and management. This article reviews the basic principles of CO2 and erbium:YAG laser resurfacing, including preoperative, intraoperative, and postoperative patient considerations. Side-effects and complications encountered after laser resurfacing are discussed with specific guidelines provided on their appropriate management. Anticipated future developments and cutting-edge research endeavors in cutaneous laser resurfacing are also briefly outlined.

Vortex information display system program description manual. [data acquisition from laser Doppler velocimeters and real time operation

NASA Technical Reports Server (NTRS)

Conway, R.; Matuck, G. N.; Roe, J. M.; Taylor, J.; Turner, A.

1975-01-01

A vortex information display system is described which provides flexible control through system-user interaction for collecting wing-tip-trailing vortex data, processing this data in real time, displaying the processed data, storing raw data on magnetic tape, and post processing raw data. The data is received from two asynchronous laser Doppler velocimeters (LDV's) and includes position, velocity, and intensity information. The raw data is written onto magnetic tape for permanent storage and is also processed in real time to locate vortices and plot their positions as a function of time. The interactive capability enables the user to make real time adjustments in processing data and provides a better definition of vortex behavior. Displaying the vortex information in real time produces a feedback capability to the LDV system operator allowing adjustments to be made in the collection of raw data. Both raw data and processing can be continually upgraded during flyby testing to improve vortex behavior studies. The post-analysis capability permits the analyst to perform in-depth studies of test data and to modify vortex behavior models to improve transport predictions.

A 2-microm continuous-wave laser system for safe and high-precision dissection during NOTES procedures.

PubMed

Dray, Xavier; Donatelli, Gianfranco; Krishnamurty, Devi Mukkai; Dubcenco, Elena; Wroblewski, Ronald J; Assumpcao, Lia; Giday, Samuel A; Buscaglia, Jonathan M; Shin, Eun J; Magno, Priscilla; Pipitone, Laurie J; Marohn, Michael R; Kantsevoy, Sergey V; Kalloo, Anthony N

2010-09-01

Lasers 2-microm in wavelength offer efficient tissue cutting with limited thermal damage in biological tissue. To evaluate the dissection capabilities of a 2-microm continuous-wave laser for NOTES procedures. We conducted 18 acute animal experiments. Group 1 (three animals): transcolonic access to the peritoneal cavity (15-W transcolonic laser puncture, balloon dilation over the laser probe). Group 2 (six animals): transcolonic access with needle-knife puncture and balloon dilation. Group 3 (three animals): transgastric access to the peritoneal cavity (similar technique as group 1) followed by laser-assisted dissection of the kidney. In one animal of group 3, a therapeutic target (hematoma) was created by percutaneous puncture of the kidney. Group 4 (six animals): transgastric access (similar to the technique of group 2). Translumenal access to the peritoneal cavity was achieved in 2-3 min in group 1 (significantly shorter than with the needle-knife-assisted technique, 4-5 min, p=0.02) and in 7-10 min in group 3 (compared to 6-17 min in group 4, p=0.88). In group 3, laser dissection of the parietal peritoneum and of perinephric connective tissue allowed access to the retroperitoneum with complete removal of a blood collection in the animal with puncture trauma. Laser dissection demonstrated good maneuverability, clean and rapid cutting, and excellent hemostasis. Peritoneoscopy and necropsy showed no damage of targeted tissue and surrounding organs. The 2-microm continuous-wave laser system showed promising capabilities for highly precise and safe dissection during NOTES procedures.

An integrated laser trap/flow control video microscope for the study of single biomolecules.

PubMed Central

Wuite, G J; Davenport, R J; Rappaport, A; Bustamante, C

2000-01-01

We have developed an integrated laser trap/flow control video microscope for mechanical manipulation of single biopolymers. The instrument is automated to maximize experimental throughput. A single-beam optical trap capable of trapping micron-scale polystyrene beads in the middle of a 200-microm-deep microchamber is used, making it possible to insert a micropipette inside this chamber to hold a second bead by suction. Together, these beads function as easily exchangeable surfaces between which macromolecules of interest can be attached. A computer-controlled flow system is used to exchange the liquid in the chamber and to establish a flow rate with high precision. The flow and the optical trap can be used to exert forces on the beads, the displacements of which can be measured either by video microscopy or by laser deflection. To test the performance of this instrument, individual biotinylated DNA molecules were assembled between two streptavidin beads, and the DNA elasticity was characterized using both laser trap and flow forces. DNA extension under varying forces was measured by video microscopy. The combination of the flow system and video microscopy is a versatile design that is particularly useful for the study of systems susceptible to laser-induced damage. This capability was demonstrated by following the translocation of transcribing RNA polymerase up to 650 s. PMID:10920045

Fourier Transform Fringe-Pattern Analysis of an Absolute Distance Michelson Interferometer for Space-Based Laser Metrology.

NASA Astrophysics Data System (ADS)

Talamonti, James Joseph

1995-01-01

Future NASA proposals include the placement of optical interferometer systems in space for a wide variety of astrophysical studies including a vastly improved deflection test of general relativity, a precise and direct calibration of the Cepheid distance scale, and the determination of stellar masses (Reasenberg et al., 1988). There are also plans for placing large array telescopes on the moon with the ultimate objective of being able to measure angular separations of less than 10 mu-arc seconds (Burns, 1990). These and other future projects will require interferometric measurement of the (baseline) distance between the optical elements comprising the systems. Eventually, space qualifiable interferometers capable of picometer (10^{-12}m) relative precision and nanometer (10^{ -9}m) absolute precision will be required. A numerical model was developed to emulate the capabilities of systems performing interferometric noncontact absolute distance measurements. The model incorporates known methods to minimize signal processing and digital sampling errors and evaluates the accuracy limitations imposed by spectral peak isolation using Hanning, Blackman, and Gaussian windows in the Fast Fourier Transform Technique. We applied this model to the specific case of measuring the relative lengths of a compound Michelson interferometer using a frequency scanned laser. By processing computer simulated data through our model, the ultimate precision is projected for ideal data, and data containing AM/FM noise. The precision is shown to be limited by non-linearities in the laser scan. A laboratory system was developed by implementing ultra-stable external cavity diode lasers into existing interferometric measuring techniques. The capabilities of the system were evaluated and increased by using the computer modeling results as guidelines for the data analysis. Experimental results measured 1-3 meter baselines with <20 micron precision. Comparison of the laboratory and modeling results showed that the laboratory precisions obtained were of the same order of magnitude as those predicted for computer generated results under similar conditions. We believe that our model can be implemented as a tool in the design for new metrology systems capable of meeting the precisions required by space-based interferometers.

Multidisciplinary model-based-engineering for laser weapon systems: recent progress

NASA Astrophysics Data System (ADS)

Coy, Steve; Panthaki, Malcolm

2013-09-01

We are working to develop a comprehensive, integrated software framework and toolset to support model-based engineering (MBE) of laser weapons systems. MBE has been identified by the Office of the Director, Defense Science and Engineering as one of four potentially "game-changing" technologies that could bring about revolutionary advances across the entire DoD research and development and procurement cycle. To be effective, however, MBE requires robust underlying modeling and simulation technologies capable of modeling all the pertinent systems, subsystems, components, effects, and interactions at any level of fidelity that may be required in order to support crucial design decisions at any point in the system development lifecycle. Very often the greatest technical challenges are posed by systems involving interactions that cut across two or more distinct scientific or engineering domains; even in cases where there are excellent tools available for modeling each individual domain, generally none of these domain-specific tools can be used to model the cross-domain interactions. In the case of laser weapons systems R&D these tools need to be able to support modeling of systems involving combined interactions among structures, thermal, and optical effects, including both ray optics and wave optics, controls, atmospheric effects, target interaction, computational fluid dynamics, and spatiotemporal interactions between lasing light and the laser gain medium. To address this problem we are working to extend Comet™, to add the addition modeling and simulation capabilities required for this particular application area. In this paper we will describe our progress to date.

Preclinical investigations of articular cartilage ablation with femtosecond and pulsed infrared lasers as an alternative to microfracture surgery

NASA Astrophysics Data System (ADS)

Su, Erica; Sun, Hui; Juhasz, Tibor; Wong, Brian J. F.

2014-09-01

Microfracture surgery is a bone marrow stimulation technique for treating cartilage defects and injuries in the knee. Current methods rely on surgical skill and instrumentation. This study investigates the potential use of laser technology as an alternate means to create the microfracture holes. Lasers investigated in this study include an erbium:YAG laser (λ=2.94 μm), titanium:sapphire femtosecond laser system (λ=1700 nm), and Nd:glass femtosecond laser (λ=1053 nm). Bovine samples were ablated at fluences of 8 to 18 J/cm2 with the erbium:YAG laser, at a power of 300±15 mW with the titanium:sapphire femtosecond system, and at an energy of 3 μJ/pulse with the Nd:glass laser. Samples were digitally photographed and histological sections were taken for analysis. The erbium:YAG laser is capable of fast and efficient ablation; specimen treated with fluences of 12 and 18 J/cm2 experienced significant amounts of bone removal and minimal carbonization with saline hydration. The femtosecond laser systems successfully removed cartilage but not clinically significant amounts of bone. Precise tissue removal was possible but not to substantial depths due to limitations of the systems. With additional studies and development, the use of femtosecond laser systems to ablate bone may be achieved at clinically valuable ablation rates.

Preclinical investigations of articular cartilage ablation with femtosecond and pulsed infrared lasers as an alternative to microfracture surgery.

PubMed

Su, Erica; Sun, Hui; Juhasz, Tibor; Wong, Brian J F

2014-09-01

Microfracture surgery is a bone marrow stimulation technique for treating cartilage defects and injuriesin the knee. Current methods rely on surgical skill and instrumentation. This study investigates the potential useof laser technology as an alternate means to create the microfracture holes. Lasers investigated in this study include an erbium:YAG laser (λ = 2.94 μm), titanium:sapphire femtosecond laser system (λ = 1700 nm), and Nd:glass femtosecond laser (λ = 1053 nm). Bovine samples were ablated at fluences of 8 to 18 J∕cm2 with the erbium:YAG laser, at a power of 300 ± 15 mW with the titanium:sapphire femtosecond system, and at an energy of 3 μJ∕pulse with the Nd:glass laser. Samples were digitally photographed and histological sections were taken for analysis. The erbium:YAG laser is capable of fast and efficient ablation; specimen treated with fluences of 12 and 18 J∕cm2 experienced significant amounts of bone removal and minimal carbonization with saline hydration. The femtosecond laser systems successfully removed cartilage but not clinically significant amounts of bone. Precise tissue removal was possible but not to substantial depths due to limitations of the systems. With additional studies and development, the use of femtosecond laser systems to ablate bone may be achieved at clinically valuable ablation rates.

Picosecond Pulse Recirculation for High Average Brightness Thomson Scattering-based Gamma-ray Sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Semenov, V. A.

2009-06-12

Pulse recirculation has been successfully demonstrated with the interaction laser system of LLNL's Thomson-Radiated Extreme X-ray (T-REX) source. The recirculation increased twenty-eight times the intensity of the light coming out of the laser system, demonstrating the capability of increasing the gamma-ray flux emitted by T-REX. The technical approach demonstrated could conceivably increase the average gamma-ray flux output by up to a hundred times.

Intense laser beams; Proceedings of the Meeting, Los Angeles, CA, Jan. 23, 24, 1992

NASA Technical Reports Server (NTRS)

Wade, Richard C. (Editor); Ulrich, Peter B. (Editor)

1992-01-01

Various papers on intense laser beams are presented. Individual topics addressed include: novel methods of copper vapor laser excitation, UCLA IR FEL, lasing characteristics of a large-bore copper vapor laser (CVL), copper density measurement of a large-bore CVL, high-power XeCl excimer laser, solid state direct-drive circuit for pumping gas lasers, united energy model for FELs, intensity and frequency instabilities in double-mode CO2 lasers, comparison of output power stabilities of CO and CO2 lasers, increasing efficiency of sealed-off CO lasers, thermal effects in singlet delta oxygen generation, optical extraction from the chemical oxygen-iodine laser medium, generation and laser diagnostic analysis of bismuth fluoride. Also discussed are: high-Q resonator design for an HF overtone chemical lasers, improved coatings for HF overtone lasers, scaled atmospheric blooming experiment, simulation on producing conjugate field using deformable mirrors, paraxial theory of amplitude correction, potential capabilities of adaptive optical systems in the atmosphere, power beaming research at NASA, system evaluations of laser power beaming options, performance projections for laser beam power to space, independent assessment of laser power beaming options, removal of atmospheric CFCs by lasers, efficiency of vaporization cutting by CVL.

Consolidated Laser-Induced Fluorescence Diagnostic Systems for the NASA Ames Arc Jet Facilities

NASA Technical Reports Server (NTRS)

Grinstead, Jay H.; Wilder, Michael C.; Porter, Barry J.; Brown, Jeffrey D.; Yeung, Dickson; Battazzo, Stephen J.; Brubaker, Timothy R.

2016-01-01

The spectroscopic diagnostic technique of two photon absorption laser-induced fluorescence (LIF) of atomic species for non-intrusive arc jet flow property measurement was first implemented at NASA Ames in the mid-1990s. In 2013-2014, NASA combined the agency's large-scale arc jet test capabilities at NASA Ames. Concurrent with that effort, the agency also sponsored a project to establish two comprehensive LIF diagnostic systems for the Aerodynamic Heating Facility (AHF) and Interaction Heating Facility (IHF) arc jets. The scope of the project enabled further engineering development of the existing IHF LIF system as well as the complete reconstruction of the AHF LIF system. The updated LIF systems are identical in design and capability. They represent the culmination of over 20 years of development experience in transitioning a specialized laboratory research tool into a measurement system for large-scale, high-demand test facilities. This paper will document the latest improvements of the LIF system design and demonstrations of the redeveloped AHF and IHF LIF systems.

Laser Science & Technology Program Annual Report - 2000

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, H-L

2001-03-20

The Laser Science and Technology (LS&T) Program Annual Report 2001 provides documentation of the achievements of the LLNL LS&T Program during the April 2001 to March 2002 period using three formats: (1) an Overview that is a narrative summary of important results for the year; (2) brief summaries of research and development activity highlights within the four Program elements: Advanced Lasers and Components (AL&C), Laser Optics and Materials (LO&M), Short Pulse Laser Applications and Technologies (SPLAT), and High-Energy Laser System and Tests (HELST); and (3) a compilation of selected articles and technical reports published in reputable scientific or technology journalsmore » in this period. All three elements (Annual Overview, Activity Highlights, and Technical Reports) are also on the Web: http://laser.llnl.gov/lasers/pubs/icfq.html. The underlying mission for the LS&T Program is to develop advanced lasers, optics, and materials technologies and applications to solve problems and create new capabilities of importance to the Laboratory and the nation. This mission statement has been our guide for defining work appropriate for our Program. A major new focus of LS&T beginning this past year has been the development of high peak power short-pulse capability for the National Ignition Facility (NIF). LS&T is committed to this activity.« less

Luminescent characteristics study of Mather-type dense plasma focus and applications to short-wavelength optical pumping. Final technical report, 1 May 1984-30 September 1985

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, K.K.

A Mather-type dense plasma focus (MDPF) system was designed, built, and tested specifically to study its luminescent characteristics and to assess its potential as a new light source of high-energy, short-wavelength lasers. The luminescence study of MDPF showed that the conversion efficiency from the electrical input to the optical output energies is at least 50%, up to the time the plasma compression is complete. Using the system, for the first time as an optical pump, laser activities were successfully obtained from a variety of liquid organic dyes. Diagnostic capabilities included an optical multichannel analyzer system complete with a computer control,more » a nitrogen-pumped tunable dye-laser system, a high-speed streak/framing camera, a digital laser energy meter, voltage and current probes, and a computer-based data-acquisition system.« less

Real-time depth measurement for micro-holes drilled by lasers

NASA Astrophysics Data System (ADS)

Lin, Cheng-Hsiang; Powell, Rock A.; Jiang, Lan; Xiao, Hai; Chen, Shean-Jen; Tsai, Hai-Lung

2010-02-01

An optical system based on the confocal principle has been developed for real-time precision measurements of the depth of micro-holes during the laser drilling process. The capability of the measuring system is theoretically predicted by the Gaussian lens formula and experimentally validated to achieve a sensitivity of 0.5 µm. A nanosecond laser system was used to drill holes, and the hole depths were measured by the proposed measuring system and by the cut-and-polish method. The differences between these two measurements are found to be 5.0% for hole depths on the order of tens of microns and 11.2% for hundreds of microns. The discrepancies are caused mainly by the roughness of the bottom surface of the hole and by the existence of debris in the hole. This system can be easily implemented in a laser workstation for the fabrication of 3D microstructures.

Underwater probing with laser radar

NASA Technical Reports Server (NTRS)

Carswell, A. I.; Sizgoric, S.

1975-01-01

Recent advances in laser and electro optics technology have greatly enhanced the feasibility of active optical probing techniques aimed at the remote sensing of water parameters. This paper describes a LIDAR (laser radar) that has been designed and constructed for underwater probing. The influence of the optical properties of water on the general design parameters of a LIDAR system is considered. Discussion of the specific details in the choice of the constructed LIDAR is given. This system utilizes a cavity dumped argon ion laser transmitter capable of 50 watt peak powers, 10 nanosecond pulses and megahertz pulse repetition rates at 10 different wavelengths in the blue green region of the spectrum. The performance of the system, in proving various types of water, is demonstrated by summarizing the results of initial laboratory and field experiments.

An experimental investigation of 235 sub UF sub 6 fission produced plasmas. [gas handling system for use with nuclear pumped laser experiments

NASA Technical Reports Server (NTRS)

Miley, G. H.

1981-01-01

A gas handling system capable of use with uranium fluoride was designed and constructed for use with nuclear pumped laser experiments using the TRIGA research reactor. By employing careful design and temperature controls, the UF6 can be first transported into the irradiation chamber, and then, at the conclusion of the experiment, returned to gas cylinders. The design of the system is described. Operating procedures for the UF6 and gas handling systems are included.

Pulse shaping and energy storage capabilities of angularly multiplexed KrF laser fusion drivers

NASA Astrophysics Data System (ADS)

Lehmberg, R. H.; Giuliani, J. L.; Schmitt, A. J.

2009-07-01

This paper describes a rep-rated multibeam KrF laser driver design for the 500kJ Inertial Fusion test Facility (FTF) recently proposed by NRL, then models its optical pulse shaping capabilities using the ORESTES laser kinetics code. It describes a stable and reliable iteration technique for calculating the required precompensated input pulse shape that will achieve the desired output shape, even when the amplifiers are heavily saturated. It also describes how this precompensation technique could be experimentally implemented in real time on a reprated laser system. The simulations show that this multibeam system can achieve a high fidelity pulse shaping capability, even for a high gain shock ignition pulse whose final spike requires output intensities much higher than the ˜4MW/cm2 saturation levels associated with quasi-cw operation; i.e., they show that KrF can act as a storage medium even for pulsewidths of ˜1ns. For the chosen pulse, which gives a predicted fusion energy gain of ˜120, the simulations predict the FTF can deliver a total on-target energy of 428kJ, a peak spike power of 385TW, and amplified spontaneous emission prepulse contrast ratios IASE/I<3×10-7 in intensity and FASE/F<1.5×10-5 in fluence. Finally, the paper proposes a front-end pulse shaping technique that combines an optical Kerr gate with cw 248nm light and a 1μm control beam shaped by advanced fiber optic technology, such as the one used in the National Ignition Facility (NIF) laser.

Estimates of forest canopy height and aboveground biomass using ICESat.

Treesearch

Michael A. Lefsky; David J. Harding; Michael Keller; Warren B. Cohen; Claudia C. Carabajal; Fernando Del Bom Espirito-Santo; Maria O. Hunter; Raimundo de Oliveira Jr.

2005-01-01

Exchange of carbon between forests and the atmosphere is a vital component of the global carbon cycle. Satellite laser altimetry has a unique capability for estimating forest canopy height, which has a direct and increasingly well understood relationship to aboveground carbon storage. While the Geoscience Laser Altimeter System (GLAS) onboard the Ice, Cloud and land...

DiPOLE: a 10 J, 10 Hz cryogenic gas cooled multi-slab nanosecond Yb:YAG laser.

PubMed

Banerjee, Saumyabrata; Ertel, Klaus; Mason, Paul D; Phillips, P Jonathan; De Vido, Mariastefania; Smith, Jodie M; Butcher, Thomas J; Hernandez-Gomez, Cristina; Greenhalgh, R Justin S; Collier, John L

2015-07-27

The Diode Pumped Optical Laser for Experiments (DiPOLE) project at the Central Laser Facility aims to develop a scalable, efficient high pulse energy diode pumped laser amplifier system based on cryogenic gas cooled, multi-slab ceramic Yb:YAG technology. We present recent results obtained from a scaled down prototype laser system designed for operation at 10 Hz pulse repetition rate. At 140 K, the system generated 10.8 J of energy in a 10 ns pulse at 1029.5 nm when pumped by 48 J of diode energy at 940 nm, corresponding to an optical to optical conversion efficiency of 22.5%. To our knowledge, this represents the highest pulse energy obtained from a cryo cooled Yb laser to date and the highest efficiency achieved by a multi-Joule diode pumped solid state laser system. Additionally, we demonstrated shot-to-shot energy stability of 0.85% rms for the system operated at 7 J, 10 Hz during several runs lasting up to 6 hours, with more than 50 hours in total. We also demonstrated pulse shaping capability and report on beam, wavefront and focal spot quality.

Safe teleoperation based on flexible intraoperative planning for robot-assisted laser microsurgery.

PubMed

Mattos, Leonardo S; Caldwell, Darwin G

2012-01-01

This paper describes a new intraoperative planning system created to improve precision and safety in teleoperated laser microsurgeries. It addresses major safety issues related to real-time control of a surgical laser during teleoperated procedures, which are related to the reliability and robustness of the telecommunication channels. Here, a safe solution is presented, consisting in a new planning system architecture that maintains the flexibility and benefits of real-time teleoperation and keeps the surgeon in control of all surgical actions. The developed system is based on our virtual scalpel system for robot-assisted laser microsurgery, and allows the intuitive use of stylus to create surgical plans directly over live video of the surgical field. In this case, surgical plans are defined as graphic objects overlaid on the live video, which can be easily modified or replaced as needed, and which are transmitted to the main surgical system controller for subsequent safe execution. In the process of improving safety, this new planning system also resulted in improved laser aiming precision and improved capability for higher quality laser procedures, both due to the new surgical plan execution module, which allows very fast and precise laser aiming control. Experimental results presented herein show that, in addition to the safety improvements, the new planning system resulted in a 48% improvement in laser aiming precision when compared to the previous virtual scalpel system.

Photonic crystal fibre enables short-wavelength two-photon laser scanning fluorescence microscopy with fura-2

NASA Astrophysics Data System (ADS)

McConnell, Gail; Riis, Erling

2004-10-01

We report on a novel and compact reliable laser source capable of short-wavelength two-photon laser scanning fluorescence microscopy based on soliton self-frequency shift effects in photonic crystal fibre. We demonstrate the function of the system by performing two-photon microscopy of smooth muscle cells and cardiac myocytes from the rat pulmonary vein and Chinese hamster ovary cells loaded with the fluorescent calcium indicator fura-2/AM.

Under-sampling in a Multiple-Channel Laser Vibrometry System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corey, Jordan

2007-03-01

Laser vibrometry is a technique used to detect vibrations on objects using the interference of coherent light with itself. Most vibrometry systems process only one target location at a time, but processing multiple locations simultaneously provides improved detection capabilities. Traditional laser vibrometry systems employ oversampling to sample the incoming modulated-light signal, however as the number of channels increases in these systems, certain issues arise such a higher computational cost, excessive heat, increased power requirements, and increased component cost. This thesis describes a novel approach to laser vibrometry that utilizes undersampling to control the undesirable issues associated with over-sampled systems. Undersamplingmore » allows for significantly less samples to represent the modulated-light signals, which offers several advantages in the overall system design. These advantages include an improvement in thermal efficiency, lower processing requirements, and a higher immunity to the relative intensity noise inherent in laser vibrometry applications. A unique feature of this implementation is the use of a parallel architecture to increase the overall system throughput. This parallelism is realized using a hierarchical multi-channel architecture based on off-the-shelf programmable logic devices (PLDs).« less

Virtual environment assessment for laser-based vision surface profiling

NASA Astrophysics Data System (ADS)

ElSoussi, Adnane; Al Alami, Abed ElRahman; Abu-Nabah, Bassam A.

2015-03-01

Oil and gas businesses have been raising the demand from original equipment manufacturers (OEMs) to implement a reliable metrology method in assessing surface profiles of welds before and after grinding. This certainly mandates the deviation from the commonly used surface measurement gauges, which are not only operator dependent, but also limited to discrete measurements along the weld. Due to its potential accuracy and speed, the use of laser-based vision surface profiling systems have been progressively rising as part of manufacturing quality control. This effort presents a virtual environment that lends itself for developing and evaluating existing laser vision sensor (LVS) calibration and measurement techniques. A combination of two known calibration techniques is implemented to deliver a calibrated LVS system. System calibration is implemented virtually and experimentally to scan simulated and 3D printed features of known profiles, respectively. Scanned data is inverted and compared with the input profiles to validate the virtual environment capability for LVS surface profiling and preliminary assess the measurement technique for weld profiling applications. Moreover, this effort brings 3D scanning capability a step closer towards robust quality control applications in a manufacturing environment.

Laser beam shaping for biomedical microscopy techniques

NASA Astrophysics Data System (ADS)

Laskin, Alexander; Kaiser, Peter; Laskin, Vadim; Ostrun, Aleksei

2016-04-01

Uniform illumination of a working field is very important in optical systems of confocal microscopy and various implementations of fluorescence microscopy like TIR, SSIM, STORM, PALM to enhance performance of these laser-based research techniques. Widely used TEM00 laser sources are characterized by essentially non-uniform Gaussian intensity profile which leads usually to non-uniform intensity distribution in a microscope working field or in a field of microlenses array of a confocal microscope optical system, this non-uniform illumination results in instability of measuring procedure and reducing precision of quantitative measurements. Therefore transformation of typical Gaussian distribution of a TEM00 laser to flat-top (top hat) profile is an actual technical task, it is solved by applying beam shaping optics. Due to high demands to optical image quality the mentioned techniques have specific requirements to a uniform laser beam: flatness of phase front and extended depth of field, - from this point of view the microscopy techniques are similar to holography and interferometry. There are different refractive and diffractive beam shaping approaches used in laser industrial and scientific applications, but only few of them are capable to fulfil the optimum conditions for beam quality required in discussed microscopy techniques. We suggest applying refractive field mapping beam shapers πShaper, which operational principle presumes almost lossless transformation of Gaussian to flat-top beam with flatness of output wavefront, conserving of beam consistency, providing collimated low divergent output beam, high transmittance, extended depth of field, negligible wave aberration, and achromatic design provides capability to work with several lasers with different wavelengths simultaneously. The main function of a beam shaper is transformation of laser intensity profile, further beam transformation to provide optimum for a particular technique spot size and shape has to be realized by an imaging optical system which can include microscope objectives and tube lenses. This paper will describe design basics of refractive beam shapers and optical layouts of their applying in microscopy systems. Examples of real implementations and experimental results will be presented as well.

Mitigation of laser damage on National Ignition Facility optics in volume production

NASA Astrophysics Data System (ADS)

Folta, James; Nostrand, Mike; Honig, John; Wong, Nan; Ravizza, Frank; Geraghty, Paul; Taranowski, Mike; Johnson, Gary; Larkin, Glenn; Ravizza, Doug; Peterson, John; Welday, Brian; Wegner, Paul

2013-12-01

The National Ignition Facility has recently achieved the milestone of delivering over 1.8 MJ and 500 TW of 351 nm laser energy and power on target, which required average fluences up to 9 J/cm2 (3 ns equivalent) in the final optics system. Commercial fused silica laser-grade UV optics typically have a maximum operating threshold of 5 J/cm2. We have developed an optics recycling process which enables NIF to operate above the laser damage initiation and growth thresholds. We previously reported a method to mitigate laser damage with laser ablation of the damage site to leave benign cone shaped pits. We have since developed a production facility with four mitigation systems capable of performing the mitigation protocols on full-sized (430 mm) optics in volume production. We have successfully repaired over 700 NIF optics (unique serial numbers), some of which have been recycled as many as 11 times. We describe the mitigation systems, the optics recycle loop process, and optics recycle production data.

Scope of Work for Integration Management and Installation Services of the National Ignition Facility Beampath Infrastructure System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coyle, P.D.

2000-04-25

The goal of the National Ignition Facility (NIF) project is to provide an aboveground experimental capability for maintaining nuclear competence and weapons effects simulation and to provide a facility capable of achieving fusion ignition using solid-state lasers as the energy driver. The facility will incorporate 192 laser beams, which will be focused onto a small target located at the center of a spherical target chamber--the energy from the laser beams will be deposited in a few billionths of a second. The target will then implode, forcing atomic nuclei to sufficiently high temperatures and densities necessary to achieve a miniature fusionmore » reaction. The NIF is under construction, at Livermore, California, located approximately 50 miles southeast of San Francisco, California.« less

Scope of Work for Integration Management and Installation Services of the National Ignition Facility Beampath Infrastructure System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coyle, P.D.

The goal of the National Ignition Facility (NIF) project is to provide an aboveground experimental capability for maintaining nuclear competence and weapons effects simulation and to provide a facility capable of achieving fusion ignition using solid-state lasers as the energy driver. The facility will incorporate 192 laser beams, which will be focused onto a small target located at the center of a spherical target chamber--the energy from the laser beams will be deposited in a few billionths of a second. The target will then implode, forcing atomic nuclei to sufficiently high temperatures and densities necessary to achieve a miniature fusionmore » reaction. The NIF is under construction, at Livermore, California, located approximately 50 miles southeast of San Francisco, California.« less

Laser propulsion to earth orbit. Has its time come?

NASA Technical Reports Server (NTRS)

Kantrowitz, Arthur

1989-01-01

Recent developments in high energy lasers, adaptive optics, and atmospheric transmission bring laser propulsion much closer to realization. Proposed here is a reference vehicle for study which consists of payload and solid propellant (e.g. ice). A suitable laser pulse is proposed for using a Laser Supported Detonation wave to produce thrust efficiently. It seems likely that a minimum system (10 Mw CO2 laser and 10 m dia. mirror) could be constructed for about $150 M. This minimum system could launch payloads of about 13 kg to a 400 km orbit every 10 minutes. The annual launch capability would be about 683 tons times the duty factor. Laser propulsion would be an order of magnitude cheaper than chemical rockets if the duty factor was 20 percent (10,000 launches/yr). Launches beyond that would be even cheaper. The chief problem which needs to be addressed before these possibilities could be realized is the design of a propellant to turn laser energy into thrust efficiently and to withstand the launch environment.

Optically pumped isotopic ammonia laser system

DOEpatents

Buchwald, Melvin I.; Jones, Claude R.; Nelson, Leonard Y.

1982-01-01

An optically pumped isotopic ammonia laser system which is capable of producing a plurality of frequencies in the middle infrared spectral region. Two optical pumping mechanisms are disclosed, i.e., pumping on R(J) and lasing on P(J) in response to enhancement of rotational cascade lasing including stimulated Raman effects, and, pumping on R(J) and lasing on P(J+2). The disclosed apparatus for optical pumping include a hole coupled cavity and a grating coupled cavity.

Linear FMCW Laser Radar for Precision Range and Vector Velocity Measurements

NASA Technical Reports Server (NTRS)

Pierrottet, Diego; Amzajerdian, Farzin; Petway, Larry; Barnes, Bruce; Lockhard, George; Rubio, Manuel

2008-01-01

An all fiber linear frequency modulated continuous wave (FMCW) coherent laser radar system is under development with a goal to aide NASA s new Space Exploration initiative for manned and robotic missions to the Moon and Mars. By employing a combination of optical heterodyne and linear frequency modulation techniques and utilizing state-of-the-art fiber optic technologies, highly efficient, compact and reliable laser radar suitable for operation in a space environment is being developed. Linear FMCW lidar has the capability of high-resolution range measurements, and when configured into a multi-channel receiver system it has the capability of obtaining high precision horizontal and vertical velocity measurements. Precision range and vector velocity data are beneficial to navigating planetary landing pods to the preselected site and achieving autonomous, safe soft-landing. The all-fiber coherent laser radar has several important advantages over more conventional pulsed laser altimeters or range finders. One of the advantages of the coherent laser radar is its ability to measure directly the platform velocity by extracting the Doppler shift generated from the motion, as opposed to time of flight range finders where terrain features such as hills, cliffs, or slopes add error to the velocity measurement. Doppler measurements are about two orders of magnitude more accurate than the velocity estimates obtained by pulsed laser altimeters. In addition, most of the components of the device are efficient and reliable commercial off-the-shelf fiber optic telecommunication components. This paper discusses the design and performance of a second-generation brassboard system under development at NASA Langley Research Center as part of the Autonomous Landing and Hazard Avoidance (ALHAT) project.

Chirped laser dispersion spectroscopy using a directly modulated quantum cascade laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hangauer, Andreas, E-mail: hangauer@princeton.edu; Nikodem, Michal; Wysocki, Gerard, E-mail: gwysocki@princeton.edu

2013-11-04

Chirped laser dispersion spectroscopy (CLaDS) utilizing direct modulation of a quantum cascade laser (QCL) is presented. By controlling the laser bias nearly single- and dual-sideband CLaDS operation can be realized in an extremely simplified optical setup with no external optical modulators. Capability of direct single-sideband modulation is a unique feature of QCLs that exhibit a low linewidth enhancement factor. The developed analytical model shows excellent agreement with the experimental, directly modulated CLaDS spectra. This method overcomes major technical limitations of mid-infrared CLaDS systems by allowing significantly higher modulation frequencies and eliminating optical fringes introduced by external modulators.

Industrial laser welding evaluation study

NASA Technical Reports Server (NTRS)

Hella, R.; Locke, E.; Ream, S.

1974-01-01

High power laser welding was evaluated for fabricating space vehicle boosters. This evaluation was made for 1/4 in. and 1/2 in. aluminum (2219) and 1/4 in. and 1/2 in. D6AC steel. The Avco HPL 10 kW industrial laser was used to perform the evaluation. The objective has been achieved through the completion of the following technical tasks: (1) parameter study to optimize welding and material parameters; (2) preparation of welded panels for MSFC evaluation; and (3) demonstration of the repeatability of laser welding equipment. In addition, the design concept for a laser welding system capable of welding large space vehicle boosters has been developed.

Diffusion-cooled high-power single-mode waveguide CO2 laser for transmyocardial revascularization

NASA Astrophysics Data System (ADS)

Berishvili, I. I.; Bockeria, L. A.; Egorov, E. N.; Golubev, Vladimir S.; Galushkin, Michail G.; Kheliminsky, A. A.; Panchenko, Vladislav Y.; Roshin, A. P.; Sigaev, I. Y.; Vachromeeva, M. N.; Vasiltsov, Victor V.; Yoshina, V. I.; Zabelin, Alexandre M.; Zelenov, Evgenii V.

1999-01-01

The paper presents the results on investigations and development of multichannel waveguide CO2 laser with diffusion cooling of active medium excited by discharge of audio-frequency alternating current. The description of high-power single-mode CO2 laser with average beam power up to 1 kW is presented. The result of measurement of the laser basic parameters are offered, as well as the outcomes of performances of the laser head with long active zone, operating in waveguide mode. As an example of application of these laser, various capabilities a description of the developed medical system 'Genom' used in the transmyocardial laser revascularization (TMLR) procedure and clinical results of the possibilities of the TMLR in the surgical treatment are presented.

Smart spectroscopy sensors: II. Narrow-band laser systems

NASA Astrophysics Data System (ADS)

Matharoo, Inderdeep; Peshko, Igor

2013-03-01

This paper describes the principles of operation of a miniature multifunctional optical sensory system based on laser technology and spectroscopic principles of analysis. The operation of the system as a remote oxygen sensor has been demonstrated. The multi-component alarm sensor has been designed to recognise gases and to measure gas concentration (O2, CO2, CO, CH4, N2O, C2H2, HI, OH radicals and H2O vapour, including semi-heavy water), temperature, pressure, humidity, and background radiation from the environment. Besides gas sensing, the same diode lasers are used for range-finding and to provide sensor self-calibration. The complete system operates as an inhomogeneous sensory network: the laser sensors are capable of using information received from environmental sensors for improving accuracy and reliability of gas concentration measurement. The sources of measurement errors associated with hardware and algorithms of operation and data processing have been analysed in detail.

Single photon ranging system using two wavelengths laser and analysis of precision

NASA Astrophysics Data System (ADS)

Chen, Yunfei; He, Weiji; Miao, Zhuang; Gu, Guohua; Chen, Qian

2013-09-01

The laser ranging system based on time correlation single photon counting technology and single photon detector has the feature of high precision and low emergent energy etc. In this paper, we established a single photon laser ranging system that use the supercontinuum laser as light source, and two wavelengths (532nm and 830nm) of echo signal as the stop signal. We propose a new method that is capable to improve the single photon ranging system performance. The method is implemented by using two single-photon detectors to receive respectively the two different wavelength signals at the same time. We extracted the firings of the two detectors triggered by the same laser pulse at the same time and then took mean time of the two firings as the combined detection time-of-flight. The detection by two channels using two wavelengths will effectively improve the detection precision and decrease the false alarm probability. Finally, an experimental single photon ranging system was established. Through a lot of experiments, we got the system precision using both single and two wavelengths and verified the effectiveness of the method.

Laser optical appraisal and design of a PRIME/Rover interface

NASA Technical Reports Server (NTRS)

Donaldson, J. A.

1980-01-01

An appraisal of whether to improve the existing multi-laser/multi detector system was undertaken. Two features of the elevation scanning mast which prevent the system from meeting desired specifications were studied. Then elevation scanning mast has 20 detectors, as opposed to the desired 40. This influences the system's overall resolution. The mirror shaft encoder's finite resolution prevents the laser from being aimed exactly as desired. This influences the system's overall accuracy. It was concluded that the existing system needs no modification at present. The design and construction of a data emulator which allowed testing data transactions with a PRIME computer is described, and theory of operation briefly discussed. A full blown PRIME/Rover Interface was designed and built. The capabilities of this Interface and its operating principles are discussed.

Generation of an ultrafast femtosecond soliton fiber laser by carbon nanotube as saturable absorber

NASA Astrophysics Data System (ADS)

Salim, M. A. M.; Ahmad, H.; Harun, S. W.; Bidin, N.; Krishnan, G.

2018-05-01

This paper reports the demonstration of ultrafast fiber laser in a simple erbium-doped fiber (EDF) laser that employed a carbon nanotube (CNT) thin film saturable absorber (SA) to generate a stable soliton pulse. The repetition rate of 10.8 MHz pulse consistently achieved has narrowest pulse width of 640 fs and 1555.78 nm central wavelength for an hour operation in room temperature. This proposed setup has the capability for reliable and stable system features.

Laser speckle strain and deformation sensor using linear array image cross-correlation method for specifically arranged triple-beam triple-camera configuration

NASA Technical Reports Server (NTRS)

Sarrafzadeh-Khoee, Adel K. (Inventor)

2000-01-01

The invention provides a method of triple-beam and triple-sensor in a laser speckle strain/deformation measurement system. The triple-beam/triple-camera configuration combined with sequential timing of laser beam shutters is capable of providing indications of surface strain and structure deformations. The strain and deformation quantities, the four variables of surface strain, in-plane displacement, out-of-plane displacement and tilt, are determined in closed form solutions.

National Ignition Facility Laser System Performance

DOE PAGES

Spaeth, Mary L.; Manes, Kenneth R.; Bowers, M.; ...

2017-03-23

The National Ignition Facility (NIF) laser is the culmination of more than 40 years of work at Lawrence Livermore National Laboratory dedicated to the delivery of laser systems capable of driving experiments for the study of high-energy-density physics. Although NIF was designed to support a number of missions, it was clear from the beginning that its biggest challenge was to meet the requirements for pursuit of inertial confinement fusion. Meeting the Project Completion Criteria for NIF in 2009 and for the National Ignition Campaign (NIC) in 2012 included meeting the NIF Functional Requirements and Primary Criteria that were established formore » the project in 1994. Finally, during NIC and as NIF transitioned to a user facility, its goals were expanded to include requirements defined by the broader user community as well as by laser system designers and operators.« less

Application of blue laser diodes and LEDs in phototherapy for neonatal jaundice

NASA Astrophysics Data System (ADS)

Hamza, Mostafa; Sayed El-Ahl, Mohammad H.; Hamza, Ahmad M.; Hamza, Aya M.; Hamza, Yahya M.

2003-10-01

The authors introduce the design of a compact phototherapy unit capable of fulfilling the recommendations of the clinical use of lasers and LEDs in phototherapy for the treatment of neonatal jaundice. The system keeps the duration of phototherapy to the minimum required for efficient treatment. Our leading clinical experience as well as the wavelength selection rules will be presented.

Preclinical investigations of articular cartilage ablation with femtosecond and pulsed infrared lasers as an alternative to microfracture surgery

PubMed Central

Su, Erica; Sun, Hui; Juhasz, Tibor; Wong, Brian J. F.

2014-01-01

Abstract. Microfracture surgery is a bone marrow stimulation technique for treating cartilage defects and injuries in the knee. Current methods rely on surgical skill and instrumentation. This study investigates the potential use of laser technology as an alternate means to create the microfracture holes. Lasers investigated in this study include an erbium:YAG laser (λ=2.94  μm), titanium:sapphire femtosecond laser system (λ=1700  nm), and Nd:glass femtosecond laser (λ=1053  nm). Bovine samples were ablated at fluences of 8 to 18  J/cm2 with the erbium:YAG laser, at a power of 300±15  mW with the titanium:sapphire femtosecond system, and at an energy of 3  μJ/pulse with the Nd:glass laser. Samples were digitally photographed and histological sections were taken for analysis. The erbium:YAG laser is capable of fast and efficient ablation; specimen treated with fluences of 12 and 18  J/cm2 experienced significant amounts of bone removal and minimal carbonization with saline hydration. The femtosecond laser systems successfully removed cartilage but not clinically significant amounts of bone. Precise tissue removal was possible but not to substantial depths due to limitations of the systems. With additional studies and development, the use of femtosecond laser systems to ablate bone may be achieved at clinically valuable ablation rates. PMID:25200394

Development of Broadband Telecommunication System for Railways using Laser Technology

NASA Astrophysics Data System (ADS)

Nakamura, Kazuki; Nakagawa, Shingo; Matsubara, Hiroshi; Tatsui, Daisuke; Seki, Kiyotaka; Haruyama, Shinichiro; Teraoka, Fumio

We developed a high-speed telecommunication system applicable to railways, to improve customer service and efficiency of operator's telecommunication between the ground facilities and trains under operations. We manufactured a mobile telecommunication system, capable of recording the transfer rate of 1Gbps in theory by applying the laser beam communication technology. We carried out a field test using trains in active service, and obtained the result of the transfer rate of approximately 700Mbps on the TCP layer between the ground and the train running at a speed of approximately 130km/h.

Contaminant Monitor Laser

NASA Technical Reports Server (NTRS)

1997-01-01

Under a Small Business Innovation Research contract from Langley Research Center, OPOTEK, Inc. developed a laser transmitter for remote sensing of water vapor in the upper atmosphere. As a leader in developing and using Differential Absorption Lidar, a remote sensing technique to monitor ozone and water vapor in the atmosphere, NASA was interested in upgrading the capabilities of its airborn laser systems. The laser transmitter developed for NASA was used for measuring water vapor in the infrared region. By broadening this concept to other wavelengths, OPOTEK believes a range of industrial applications can be met. In addition, the tunable laser system can be used by the Drug Enforcement Administration to discern the by-products from illegal drug manufacturing. A host of other government, university, and industrial laboratory uses for the technology are also being examined as follow-up by the company.

Estimability and simple dynamical analyses of range (range-rate range-difference) observations to artificial satellites. [laser range observations to LAGEOS using non-Bayesian statistics

NASA Technical Reports Server (NTRS)

Vangelder, B. H. W.

1978-01-01

Non-Bayesian statistics were used in simulation studies centered around laser range observations to LAGEOS. The capabilities of satellite laser ranging especially in connection with relative station positioning are evaluated. The satellite measurement system under investigation may fall short in precise determinations of the earth's orientation (precession and nutation) and earth's rotation as opposed to systems as very long baseline interferometry (VLBI) and lunar laser ranging (LLR). Relative station positioning, determination of (differential) polar motion, positioning of stations with respect to the earth's center of mass and determination of the earth's gravity field should be easily realized by satellite laser ranging (SLR). The last two features should be considered as best (or solely) determinable by SLR in contrast to VLBI and LLR.

Advanced 2-micron Solid-state Laser for Wind and CO2 Lidar Applications

NASA Technical Reports Server (NTRS)

Yu, Jirong; Trieu, Bo C.; Petros, Mulugeta; Bai, Yingxin; Petzar, Paul J.; Koch, Grady J.; Singh, Upendra N.; Kavaya, Michael J.

2006-01-01

Significant advancements in the 2-micron laser development have been made recently. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar (DIAL) system for measuring atmospheric CO2 concentration profiles. The world record 2-micron laser energy is demonstrated with an oscillator and two amplifiers system. It generates more than one joule per pulse energy with excellent beam quality. Based on the successful demonstration of a fully conductive cooled oscillator by using heat pipe technology, an improved fully conductively cooled 2-micron amplifier was designed, manufactured and integrated. It virtually eliminates the running coolant to increase the overall system efficiency and reliability. In addition to technology development and demonstration, a compact and engineering hardened 2-micron laser is under development. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser is expected to be integrated to a lidar system and take field measurements. The recent achievements push forward the readiness of such a laser system for space lidar applications. This paper will review the developments of the state-of-the-art solid-state 2-micron laser.

Laser-based satellite communication systems stabilized by non-mechanical electro-optic scanners

NASA Astrophysics Data System (ADS)

Ziemkiewicz, Michael; Davis, Scott R.; Rommel, Scott D.; Gann, Derek; Luey, Benjamin; Gamble, Joseph D.; Anderson, Mike

2016-05-01

Laser communications systems provide numerous advantages for establishing satellite-to-ground data links. As a carrier for information, lasers are characterized by high bandwidth and directionality, allowing for fast and secure transfer of data. These systems are also highly resistant to RF influences since they operate in the infrared portion of the electromagnetic spectrum, far from radio bands. In this paper we will discuss an entirely non-mechanical electro-optic (EO) laser beam steering technology, with no moving parts, which we have used to form robust 400 Mbps optical data connections through air. This technology will enable low cost, compact, and rugged free space optical (FSO) communication modules for small satellite applications. The EO beam-steerer at the heart of this system is used to maintain beam pointing as the satellite orbits. It is characterized by extremely low values for size, weight and power consumption (SWaP) - approximately 300 cm3, 300 g, and 5 W respectively, which represents a marked improvement compared to heavy, and power-consuming gimbal mechanisms. It is capable of steering a 500 mW, 1 mm short wave infrared (SWIR) beam over a field of view (FOV) of up to 50° x 15°, a range which can be increased by adding polarization gratings, which provide a coarse adjust stage at the EO beam scanner output. We have integrated this device into a communication system and demonstrated the capability to lock on and transmit a high quality data stream by modulation of SWIR power.

Intraluminal ultrasound guidance of transverse laser coronary atherectomy

NASA Astrophysics Data System (ADS)

Aretz, H. Thomas; Martinelli, Michael A.; LeDet, Earl G.; Sedlacek, Tomas; Hatch, G. F.; Gregg, Richard E.

1990-07-01

A coronary laser atherectomy system combining laser delivery and ultrasonic imaging capability is described. The system is being developed by Intra-Sonix, Inc. to treat severe stenoses. The imaging system provides the clinician with the guidance needed to remove substantial plaque without perforation. The ultrasound transducers and laser optics are mounted in a small (less than 4 F), flexible catheter, that is deliverable over a standard guidewire (0.016 inch). The laser and ultrasound beams are directed at the artery wall to permit debulking of lesions and ultrasonic depth profiling of the tissue structure throughout the thickness of the artery. This allows the physician to determine the level of therapy to be applied and to monitor the plaque removal as the therapy progresses. The precise location of the ultrasound and laser beams in the artery is determined by a navigation system. Navigation data are processed electronically in conjunction with ultrasound data to produce real-time cross-sectional and longitudinal images of the artery wall at selected locations, which are updated as the catheter progresses through the vessel lumen. Results of in vitro tests on human atherosclerotic arteries and early in vivo experiments in a canine-human xenograft model showing image construction and radial laser delivery are discussed.

Laser-Assisted Wire Additive Manufacturing System for the Deep Space Gateway

NASA Astrophysics Data System (ADS)

Foster, B. D.; Matthews, B.

2018-02-01

Investigation on the Deep Space Gateway will involve experiments/operations inside pressurized modules. Support for those experiments may necessitate a means to fabricate and repair required articles. This capability can be provided through an additive manufacturing (AM) system.

Design and optimization of a flexible high-peak-power laser-to-fiber coupled illumination system used in digital particle image velocimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robinson, Ronald A.; Ilev, Ilko K.

We present a study on the design and parameter optimization of a flexible high-peak-power fiber-optic laser delivery system using commercially available solid-core silica fibers and an experimental glass hollow waveguide (HW). The fiber-optic delivery system provides a flexible, safe, and easily and precisely positioned laser irradiation for many applications including uniform illumination for digital particle image velocimetry (DPIV). The delivery fibers, when coupled through a line-generating lens, produce a uniform thin laser sheet illumination for accurate and repeatable DPIV two-dimensional velocity measurements. We report experimental results on homogenizing the laser beam profile using various mode-mixing techniques. Furthermore, because a fundamentalmore » problem for fiber-optic-based high-peak-power laser delivery systems is the possible damage effects of the fiber material, we determine experimentally the peak power density damage threshold of various delivery fibers designed for the visible spectral range at a typical DPIV laser wavelength of 532 nm. In the case of solid-core silica delivery fibers using conventional lens-based laser-to-fiber coupling, the damage threshold varies from 3.7 GW/cm{sup 2} for a 100-{mu}m-core-diameter high-temperature fiber to 3.9 GW/cm{sup 2} for a 200-{mu}m-core-diameter high-power delivery fiber, with a total output laser energy delivered of at least 3-10 mJ for those respective fibers. Therefore, these fibers are marginally suitable for most macro-DPIV applications. However, to improve the high-power delivery capability for close-up micro-DPIV applications, we propose and validate an experimental fiber link with much higher laser power delivery capability than the solid-core fiber links. We use an uncoated grazing-incidence-based tapered glass funnel coupled to a glass HW with hollow air-core diameter of 700 {mu}m, a low numerical aperture of 0.05, and a thin inside cladding of cyclic olefin polymer coating for optimum transmission at 532 nm. Because of the mode homogenizing effect and lower power density, the taper-waveguide laser delivery technique ensured high damage threshold for the delivery HW, and as a result, no damage occurred at the maximum measured input laser energy of 33 mJ used in this study.« less

Laser-plasma accelerator-based single-cycle attosecond undulator source

NASA Astrophysics Data System (ADS)

Tibai, Z.; Tóth, Gy.; Nagyváradi, A.; Sharma, A.; Mechler, M. I.; Fülöp, J. A.; Almási, G.; Hebling, J.

2018-06-01

Laser-plasma accelerators (LPAs), producing high-quality electron beams, provide an opportunity to reduce the size of free-electron lasers (FELs) to only a few meters. A complete system is proposed here, which is based on FEL technology and consists of an LPA, two undulators, and other magnetic devices. The system is capable to generate carrier-envelope phase stable attosecond pulses with engineered waveform. Pulses with up to 60 nJ energy and 90-400 attosecond duration in the 30-120 nm wavelength range are predicted by numerical simulation. These pulses can be used to investigate ultrafast field-driven electron dynamics in matter.

Design and performance of a production-worthy excimer-laser-based stepper

NASA Astrophysics Data System (ADS)

Unger, Robert; Sparkes, Christopher; Disessa, Peter A.; Elliott, David J.

1992-06-01

Excimer-laser-based steppers have matured to a production-worthy state. Widefield high-NA lenses have been developed and characterized for imaging down to 0.35 micron and below. Excimer lasers have attained practical levels of performance capability and stability, reliability, safety, and operating cost. Excimer stepper system integration and control issues such as focus, exposure, and overlay stability have been addressed. Enabling support technologies -- resist systems, resist processing, metrology and conventional mask making -- continue to progress and are becoming available. This paper discusses specific excimer stepper design challenges, and presents characterization data from several field installations of XLSTM deep-UV steppers configured with an advanced lens design.

Double-pulse standoff laser-induced breakdown spectroscopy for versatile hazardous materials detection

NASA Astrophysics Data System (ADS)

Gottfried, Jennifer L.; De Lucia, Frank C.; Munson, Chase A.; Miziolek, Andrzej W.

2007-12-01

We have developed a double-pulse standoff laser-induced breakdown spectroscopy (ST-LIBS) system capable of detecting a variety of hazardous materials at tens of meters. The use of a double-pulse laser improves the sensitivity and selectivity of ST-LIBS, especially for the detection of energetic materials. In addition to various metallic and plastic materials, the system has been used to detect bulk explosives RDX and Composition-B, explosive residues, biological species such as the anthrax surrogate Bacillus subtilis, and chemical warfare simulants at 20 m. We have also demonstrated the discrimination of explosive residues from various interferents on an aluminum substrate.

A Compact, Solid-State UV (266 nm) Laser System Capable of Burst-Mode Operation for Laser Ablation Desorption Processing

NASA Technical Reports Server (NTRS)

Arevalo, Ricardo, Jr.; Coyle, Barry; Paulios, Demetrios; Stysley, Paul; Feng, Steve; Getty, Stephanie; Binkerhoff, William

2015-01-01

Compared to wet chemistry and pyrolysis techniques, in situ laser-based methods of chemical analysis provide an ideal way to characterize precious planetary materials without requiring extensive sample processing. In particular, laser desorption and ablation techniques allow for rapid, reproducible and robust data acquisition over a wide mass range, plus: Quantitative, spatially-resolved measurements of elemental and molecular (organic and inorganic) abundances; Low analytical blanks and limits-of-detection ( ng g-1); and, the destruction of minimal quantities of sample ( g) compared to traditional solution and/or pyrolysis analyses (mg).

ManPortable and UGV LIVAR: advances in sensor suite integration bring improvements to target observation and identification for the electronic battlefield

NASA Astrophysics Data System (ADS)

Lynam, Jeff R.

2001-09-01

A more highly integrated, electro-optical sensor suite using Laser Illuminated Viewing and Ranging (LIVAR) techniques is being developed under the Army Advanced Concept Technology- II (ACT-II) program for enhanced manportable target surveillance and identification. The ManPortable LIVAR system currently in development employs a wide-array of sensor technologies that provides the foot-bound soldier and UGV significant advantages and capabilities in lightweight, fieldable, target location, ranging and imaging systems. The unit incorporates a wide field-of-view, 5DEG x 3DEG, uncooled LWIR passive sensor for primary target location. Laser range finding and active illumination is done with a triggered, flash-lamp pumped, eyesafe micro-laser operating in the 1.5 micron region, and is used in conjunction with a range-gated, electron-bombarded CCD digital camera to then image the target objective in a more- narrow, 0.3$DEG, field-of-view. Target range determination is acquired using the integrated LRF and a target position is calculated using data from other onboard devices providing GPS coordinates, tilt, bank and corrected magnetic azimuth. Range gate timing and coordinated receiver optics focus control allow for target imaging operations to be optimized. The onboard control electronics provide power efficient, system operations for extended field use periods from the internal, rechargeable battery packs. Image data storage, transmission, and processing performance capabilities are also being incorporated to provide the best all-around support, for the electronic battlefield, in this type of system. The paper will describe flash laser illumination technology, EBCCD camera technology with flash laser detection system, and image resolution improvement through frame averaging.

Transceiver for Space Station Freedom

NASA Technical Reports Server (NTRS)

Fitzmaurice, M.; Bruno, R.

1990-01-01

This paper describes the design of the Laser Communication Transceiver (LCT) system which was planned to be flight tested as an attached payload on Space Station Freedom. The objective in building and flight-testing the LCT is to perform a broad class of tests addressing the critical aspects of space-based optical communications systems, providing a base of experience for applying laser communications technology toward future communications needs. The LCT's functional and performance requirements and capabilities with respect to acquisition, spatial tracking and pointing, communications, and attitude determination are discussed.

Transceiver for Space Station Freedom

NASA Astrophysics Data System (ADS)

Fitzmaurice, M.; Bruno, R.

1990-07-01

This paper describes the design of the Laser Communication Transceiver (LCT) system which was planned to be flight tested as an attached payload on Space Station Freedom. The objective in building and flight-testing the LCT is to perform a broad class of tests addressing the critical aspects of space-based optical communications systems, providing a base of experience for applying laser communications technology toward future communications needs. The LCT's functional and performance requirements and capabilities with respect to acquisition, spatial tracking and pointing, communications, and attitude determination are discussed.

Laser ignition of an experimental combustion chamber with a multi-injector configuration at low pressure conditions

NASA Astrophysics Data System (ADS)

Börner, Michael; Manfletti, Chiara; Kroupa, Gerhard; Oschwald, Michael

2017-09-01

In search of reliable and light-weight ignition systems for re-ignitable upper stage engines, a laser ignition system was adapted and tested on an experimental combustion chamber for propellant injection into low combustion chamber pressures at 50-80 mbar. The injector head pattern consisted of five coaxial injector elements. Both, laser-ablation-driven ignition and laser-plasma-driven ignition were tested for the propellant combination liquid oxygen and gaseous hydrogen. The 122 test runs demonstrated the reliability of the ignition system for different ignition configurations and negligible degradation due to testing. For the laser-plasma-driven scheme, minimum laser pulse energies needed for 100% ignition probability were found to decrease when increasing the distance of the ignition location from the injector faceplate with a minimum of 2.6 mJ. For laser-ablation-driven ignition, the minimum pulse energy was found to be independent of the ablation material tested and was about 1.7 mJ. The ignition process was characterized using both high-speed Schlieren and OH* emission diagnostics. Based on these findings and on the increased fiber-based pulse transport capabilities recently published, new ignition system configurations for space propulsion systems relying on fiber-based pulse delivery are formulated. If the laser ignition system delivers enough pulse energy, the laser-plasma-driven configuration represents the more versatile configuration. If the laser ignition pulse power is limited, the application of laser-ablation-driven ignition is an option to realize ignition, but implies restrictions concerning the location of ignition.

Frequency domain laser velocimeter signal processor

NASA Technical Reports Server (NTRS)

Meyers, James F.; Murphy, R. Jay

1991-01-01

A new scheme for processing signals from laser velocimeter systems is described. The technique utilizes the capabilities of advanced digital electronics to yield a signal processor capable of operating in the frequency domain maximizing the information obtainable from each signal burst. This allows a sophisticated approach to signal detection and processing, with a more accurate measurement of the chirp frequency resulting in an eight-fold increase in measurable signals over the present high-speed burst counter technology. Further, the required signal-to-noise ratio is reduced by a factor of 32, allowing measurements within boundary layers of wind tunnel models. Measurement accuracy is also increased up to a factor of five.

Laser beam welding quality monitoring system based in high-speed (10 kHz) uncooled MWIR imaging sensors

NASA Astrophysics Data System (ADS)

Linares, Rodrigo; Vergara, German; Gutiérrez, Raúl; Fernández, Carlos; Villamayor, Víctor; Gómez, Luis; González-Camino, Maria; Baldasano, Arturo; Castro, G.; Arias, R.; Lapido, Y.; Rodríguez, J.; Romero, Pablo

2015-05-01

The combination of flexibility, productivity, precision and zero-defect manufacturing in future laser-based equipment are a major challenge that faces this enabling technology. New sensors for online monitoring and real-time control of laserbased processes are necessary for improving products quality and increasing manufacture yields. New approaches to fully automate processes towards zero-defect manufacturing demand smarter heads where lasers, optics, actuators, sensors and electronics will be integrated in a unique compact and affordable device. Many defects arising in laser-based manufacturing processes come from instabilities in the dynamics of the laser process. Temperature and heat dynamics are key parameters to be monitored. Low cost infrared imagers with high-speed of response will constitute the next generation of sensors to be implemented in future monitoring and control systems for laser-based processes, capable to provide simultaneous information about heat dynamics and spatial distribution. This work describes the result of using an innovative low-cost high-speed infrared imager based on the first quantum infrared imager monolithically integrated with Si-CMOS ROIC of the market. The sensor is able to provide low resolution images at frame rates up to 10 KHz in uncooled operation at the same cost as traditional infrared spot detectors. In order to demonstrate the capabilities of the new sensor technology, a low-cost camera was assembled on a standard production laser welding head, allowing to register melting pool images at frame rates of 10 kHz. In addition, a specific software was developed for defect detection and classification. Multiple laser welding processes were recorded with the aim to study the performance of the system and its application to the real-time monitoring of laser welding processes. During the experiments, different types of defects were produced and monitored. The classifier was fed with the experimental images obtained. Self-learning strategies were implemented with very promising results, demonstrating the feasibility of using low-cost high-speed infrared imagers in advancing towards a real-time / in-line zero-defect production systems.

New developments in laser-heated diamond anvil cell with in situ synchrotron x-ray diffraction at High Pressure Collaborative Access Team

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Yue; Hrubiak, Rostislav; Rod, Eric

An overview of the in situ laser heating system at the High Pressure Collaborative Access Team, with emphasis on newly developed capabilities, is presented. Since its establishment at the beamline 16-ID-B a decade ago, laser-heated diamond anvil cell coupled with in situ synchrotron x-ray diffraction has been widely used for studying the structural properties of materials under simultaneous high pressure and high temperature conditions. Recent developments in both continuous-wave and modulated heating techniques have been focusing on resolving technical issues of the most challenging research areas. Furthermore, the new capabilities have demonstrated clear benefits and provide new opportunities in researchmore » areas including high-pressure melting, pressure-temperature-volume equations of state, chemical reaction, and time resolved studies.« less

New developments in laser-heated diamond anvil cell with in situ synchrotron x-ray diffraction at High Pressure Collaborative Access Team

DOE PAGES

Meng, Yue; Hrubiak, Rostislav; Rod, Eric; ...

2015-07-17

An overview of the in situ laser heating system at the High Pressure Collaborative Access Team, with emphasis on newly developed capabilities, is presented. Since its establishment at the beamline 16-ID-B a decade ago, laser-heated diamond anvil cell coupled with in situ synchrotron x-ray diffraction has been widely used for studying the structural properties of materials under simultaneous high pressure and high temperature conditions. Recent developments in both continuous-wave and modulated heating techniques have been focusing on resolving technical issues of the most challenging research areas. Furthermore, the new capabilities have demonstrated clear benefits and provide new opportunities in researchmore » areas including high-pressure melting, pressure-temperature-volume equations of state, chemical reaction, and time resolved studies.« less

New developments in laser-heated diamond anvil cell with in situ synchrotron x-ray diffraction at High Pressure Collaborative Access Team

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Yue; Hrubiak, Rostislav; Rod, Eric

An overview of the in situ laser heating system at the High Pressure Collaborative Access Team, with emphasis on newly developed capabilities, is presented. Since its establishment at the beamline 16-ID-B a decade ago, laser-heated diamond anvil cell coupled with in situ synchrotron x-ray diffraction has been widely used for studying the structural properties of materials under simultaneous high pressure and high temperature conditions. Recent developments in both continuous-wave and modulated heating techniques have been focusing on resolving technical issues of the most challenging research areas. The new capabilities have demonstrated clear benefits and provide new opportunities in research areasmore » including high-pressure melting, pressure-temperature-volume equations of state, chemical reaction, and time resolved studies.« less

A Comparative Study of Cycle Variability of Laser Plug Ignition vs Classical Spark Plug Ignition in Combustion Engines

NASA Astrophysics Data System (ADS)

Done, Bogdan

2017-10-01

Over the past 30 years numerous studies and laboratory experiments have researched the use of laser energy to ignite gas and fuel-air mixtures. The actual implementation of this laser application has still to be fully achieved in a commercial automotive application. Laser Plug Ignition as a replacement for Spark Plug Ignition in the internal combustion engines of automotive vehicles, offers several potential benefits such as extending lean burn capability, reducing the cyclic variability between combustion cycles and decreasing the total amount of ignition costs, and implicitly weight and energy requirements. The paper presents preliminary results of cycle variability study carried on a SI Engine equipped with laser Plug Ignition system. Versus classic ignition system, the use of the laser Plug Ignition system assures the reduction of the combustion process variability, reflected in the lower values of the coefficient of variability evaluated for indicated mean effective pressure, maximum pressure, maximum pressure angle and maximum pressure rise rate. The laser plug ignition system was mounted on an experimental spark ignition engine and tested at the regime of 90% load and 2800 rev/min, at dosage of λ=1.1. Compared to conventional spark plug, laser ignition assures the efficiency at lean dosage.

Low Power Ground-Based Laser Illumination for Electric Propulsion Applications

NASA Technical Reports Server (NTRS)

Lapointe, Michael R.; Oleson, Steven R.

1994-01-01

A preliminary evaluation of low power, ground-based laser powered electric propulsion systems is presented. A review of available and near-term laser, photovoltaic, and adaptive optic systems indicates that approximately 5-kW of ground-based laser power can be delivered at an equivalent one-sun intensity to an orbit of approximately 2000 km. Laser illumination at the proper wavelength can double photovoltaic array conversion efficiencies compared to efficiencies obtained with solar illumination at the same intensity, allowing a reduction in array mass. The reduced array mass allows extra propellant to be carried with no penalty in total spacecraft mass. The extra propellant mass can extend the satellite life in orbit, allowing additional revenue to be generated. A trade study using realistic cost estimates and conservative ground station viewing capability was performed to estimate the number of communication satellites which must be illuminated to make a proliferated system of laser ground stations economically attractive. The required number of satellites is typically below that of proposed communication satellite constellations, indicating that low power ground-based laser beaming may be commercially viable. However, near-term advances in low specific mass solar arrays and high energy density batteries for LEO applications would render the ground-based laser system impracticable.

Laser Radar Study Using Resonance Absorption for Remote Detection Of Air Pollutants

NASA Technical Reports Server (NTRS)

Igarashi, Takashi

1973-01-01

A laser radar using resonance absorption has an advantage of increased detection range and sensitivity compared with that achieved by Raman or resonance back scattering. In this paper, new laser radar system using resonance absorption is proposed and results obtained from this laser radar system are discussed. NO2, SO2 gas has an absorption spectrum at 4500 A and 3000 A respectively as shown in Fig. 1. A laser light including at least a set of an absorption peak (lambda)1 and a valley (lambda)2 is emitted into a pollutant atmosphere. The light reflected with a topographical reflector or an atmospheric Mie scattering as distributed reflectors is received and divided into two wavelength components (lambda)1 and (lambda)2. The laser radar system used in the investigation is shown in Fig', 2 and consists of a dye laser transmitter, an optical receiver with a special monochrometer and a digital processer. Table 1 shows the molecular constants of NO2, and SO2 and the dye laser used in this experiment. In this system, the absolute concentration of the pollutant gas can be measured in comparison with a standard gas cell. The concentration of NO2, SO2 as low as 0.1 ppm have been measured at 100 m depth resolution. For a 1 mJ laser output, the observable range of this system achieved up to 300 m using the distributed Mie reflector. The capability and technical limitation of the system will be discussed in detail.

Battlefield training in impaired visibility

NASA Astrophysics Data System (ADS)

Gammarino, Rudolph R.; Surhigh, James W.

1991-04-01

A laser training system entitled Shoot Through Obscuration MILES (STOM) is being developed to operate with Forward Looking InfraRed (FLIR) systems during battlefield exercises where visibility is impaired. The STOM system is capable of ranges in excess of 6 km and can penetrate battlefield obscurants such as fog-oil, smoke, dust, and rain.

Introduction of laser initiation for the 48-inch Advanced Solid Rocket Motor (ASRM) test motors at Marshall Space Flight Center (MSFC)

NASA Technical Reports Server (NTRS)

Zimmerman, Chris J.; Litzinger, Gerald E.

1993-01-01

The Advanced Solid Rocket Motor is a new design for the Space Shuttle Solid Rocket Booster. The new design will provide more thrust and more payload capability, as well as incorporating many design improvements in all facets of the design and manufacturing process. A 48-inch (diameter) test motor program is part of the ASRM development program. This program has multiple purposes for testing of propellent, insulation, nozzle characteristics, etc. An overview of the evolution of the 48-inch ASRM test motor ignition system which culminated with the implementation of a laser ignition system is presented. The laser system requirements, development, and operation configuration are reviewed in detail.

High-speed ultrafast laser machining with tertiary beam positioning (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yang, Chuan; Zhang, Haibin

2017-03-01

For an industrial laser application, high process throughput and low average cost of ownership are critical to commercial success. Benefiting from high peak power, nonlinear absorption and small-achievable spot size, ultrafast lasers offer advantages of minimal heat affected zone, great taper and sidewall quality, and small via capability that exceeds the limits of their predecessors in via drilling for electronic packaging. In the past decade, ultrafast lasers have both grown in power and reduced in cost. For example, recently, disk and fiber technology have both shown stable operation in the 50W to 200W range, mostly at high repetition rate (beyond 500 kHz) that helps avoid detrimental nonlinear effects. However, to effectively and efficiently scale the throughput with the fast-growing power capability of the ultrafast lasers while keeping the beneficial laser-material interactions is very challenging, mainly because of the bottleneck imposed by the inertia-related acceleration limit and servo gain bandwidth when only stages and galvanometers are being used. On the other side, inertia-free scanning solutions like acoustic optics and electronic optical deflectors have small scan field, and therefore not suitable for large-panel processing. Our recent system developments combine stages, galvanometers, and AODs into a coordinated tertiary architecture for high bandwidth and meanwhile large field beam positioning. Synchronized three-level movements allow extremely fast local speed and continuous motion over the whole stage travel range. We present the via drilling results from such ultrafast system with up to 3MHz pulse to pulse random access, enabling high quality low cost ultrafast machining with emerging high average power laser sources.

Image analysis algorithms for the advanced radiographic capability (ARC) grating tilt sensor at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Roberts, Randy S.; Bliss, Erlan S.; Rushford, Michael C.; Halpin, John M.; Awwal, Abdul A. S.; Leach, Richard R.

2014-09-01

The Advance Radiographic Capability (ARC) at the National Ignition Facility (NIF) is a laser system designed to produce a sequence of short pulses used to backlight imploding fuel capsules. Laser pulses from a short-pulse oscillator are dispersed in wavelength into long, low-power pulses, injected in the NIF main laser for amplification, and then compressed into high-power pulses before being directed into the NIF target chamber. In the target chamber, the laser pulses hit targets which produce x-rays used to backlight imploding fuel capsules. Compression of the ARC laser pulses is accomplished with a set of precision-surveyed optical gratings mounted inside of vacuum vessels. The tilt of each grating is monitored by a measurement system consisting of a laser diode, camera and crosshair, all mounted in a pedestal outside of the vacuum vessel, and a mirror mounted on the back of a grating inside the vacuum vessel. The crosshair is mounted in front of the camera, and a diffraction pattern is formed when illuminated with the laser diode beam reflected from the mirror. This diffraction pattern contains information related to relative movements between the grating and the pedestal. Image analysis algorithms have been developed to determine the relative movements between the gratings and pedestal. In the paper we elaborate on features in the diffraction pattern, and describe the image analysis algorithms used to monitor grating tilt changes. Experimental results are provided which indicate the high degree of sensitivity provided by the tilt sensor and image analysis algorithms.

Data acquisition and analysis of range-finding systems for spacing construction

NASA Technical Reports Server (NTRS)

Shen, C. N.

1981-01-01

For space missions of future, completely autonomous robotic machines will be required to free astronauts from routine chores of equipment maintenance, servicing of faulty systems, etc. and to extend human capabilities in hazardous environments full of cosmic and other harmful radiations. In places of high radiation and uncontrollable ambient illuminations, T.V. camera based vision systems cannot work effectively. However, a vision system utilizing directly measured range information with a time of flight laser rangefinder, can successfully operate under these environments. Such a system will be independent of proper illumination conditions and the interfering effects of intense radiation of all kinds will be eliminated by the tuned input of the laser instrument. Processing the range data according to certain decision, stochastic estimation and heuristic schemes, the laser based vision system will recognize known objects and thus provide sufficient information to the robot's control system which can develop strategies for various objectives.

Active eye-tracking for an adaptive optics scanning laser ophthalmoscope

PubMed Central

Sheehy, Christy K.; Tiruveedhula, Pavan; Sabesan, Ramkumar; Roorda, Austin

2015-01-01

We demonstrate a system that combines a tracking scanning laser ophthalmoscope (TSLO) and an adaptive optics scanning laser ophthalmoscope (AOSLO) system resulting in both optical (hardware) and digital (software) eye-tracking capabilities. The hybrid system employs the TSLO for active eye-tracking at a rate up to 960 Hz for real-time stabilization of the AOSLO system. AOSLO videos with active eye-tracking signals showed, at most, an amplitude of motion of 0.20 arcminutes for horizontal motion and 0.14 arcminutes for vertical motion. Subsequent real-time digital stabilization limited residual motion to an average of only 0.06 arcminutes (a 95% reduction). By correcting for high amplitude, low frequency drifts of the eye, the active TSLO eye-tracking system enabled the AOSLO system to capture high-resolution retinal images over a larger range of motion than previously possible with just the AOSLO imaging system alone. PMID:26203370

A 3-component laser-Doppler velocimeter data acquisition and reduction system

NASA Technical Reports Server (NTRS)

Rodman, L. C.; Bell, J. H.; Mehta, R. D.

1985-01-01

A laser doppler velocimeter capable of measuring all three components of velocity simultaneously in low-speed flows is described. All the mean velocities, Reynolds stresses, and higher-order products can be evaluated. The approach followed is to split one of the two colors used in a 2-D system, thus creating a third set of beams which is then focused in the flow from an off-axis direction. The third velocity component is computed from the known geometry of the system. The laser optical hardware and the data acquisition electronics are described in detail. In addition, full operating procedures and listings of the software (written in BASIC and ASSEMBLY languages) are also included. Some typical measurements obtained with this system in a vortex/mixing layer interaction are presented and compared directly to those obtained with a cross-wire system.

LANL compact laser pumping simulation. Final task report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feldman, B.S.; White, J.

1987-09-28

Rockwell has been tasked with the objective of both qualitatively and quantitatively defining the performance of LANL Compact Laser coupling systems. The performance criteria of the system will be based upon the magnitude and uniformity of the energy distribution in the laser pumping rod. Once this is understood, it will then be possible to improve the device performance via changes in the system`s component parameters. For this study, the authors have chosen to use the Los Alamos Radiometry Code (LARC), which was previously developed by Rockwell. LARC, as an analysis tool, is well suited for this problem because the codemore » contains the needed photometric calculation capability and easily handles the three-dimensionality of the problem. Also, LARC`s internal graphics can provide very informative visual displays of the optical system.« less

Damage Characterization of EBC-SiCSiC Ceramic Matrix Composites Under Imposed Thermal Gradient Testing

NASA Technical Reports Server (NTRS)

Appleby, Matthew P.; Morscher, Gregory N.; Zhu, Dongming

2014-01-01

Due to their high temperature capabilities, Ceramic Matrix Composite (CMC) components are being developed for use in hot-section aerospace engine applications. Harsh engine environments have led to the development of Environmental Barrier Coatings (EBCs) for silicon-based CMCs to further increase thermal and environmental capabilities. This study aims at understanding the damage mechanisms associated with these materials under simulated operating conditions. A high heat-flux laser testing rig capable of imposing large through-thickness thermal gradients by means of controlled laser beam heating and back-side air cooling is used. Tests are performed on uncoated composites, as well as CMC substrates that have been coated with state-of-the-art ceramic EBC systems. Results show that the use of the EBCs may help increase temperature capability and creep resistance by reducing the effects of stressed oxidation and environmental degradation. Also, the ability of electrical resistance (ER) and acoustic emission (AE) measurements to monitor material condition and damage state during high temperature testing is shown; suggesting their usefulness as a valuable health monitoring technique. Micromechanics models are used to describe the localized stress state of the composite system, which is utilized along with ER modeling concepts to develop an electromechanical model capable of characterizing material behavior.

Non-Invasive Tissue Oxygenation Measurement Systems. Phase 1.

DTIC Science & Technology

1995-10-01

vessels was shown ( in vivo hamster studies) to be a significant factor causing considerable variability in SaO2 in vessels ...shows that trends in blood oxygenation are tracked. The nearly universal applicability and turnkey type measurement capability of pulse oximeters are...approach early in Phase I that might be compatible with laser doppler blood flow measurements. Both methods depend on laser irradiation of the sample

A compact free space quantum key distribution system capable of daylight operation

NASA Astrophysics Data System (ADS)

Benton, David M.; Gorman, Phillip M.; Tapster, Paul R.; Taylor, David M.

2010-06-01

A free space quantum key distribution system has been demonstrated. Consideration has been given to factors such as field of view and spectral width, to cut down the deleterious effect from background light levels. Suitable optical sources such as lasers and RCLEDs have been investigated as well as optimal wavelength choices, always with a view to building a compact and robust system. The implementation of background reduction measures resulted in a system capable of operating in daylight conditions. An autonomous system was left running and generating shared key material continuously for over 7 days.

Progress in coherent lithography using table-top extreme ultraviolet lasers

NASA Astrophysics Data System (ADS)

Li, Wei

Nanotechnology has drawn a wide variety of attention as interesting phenomena occurs when the dimension of the structures is in the nanometer scale. The particular characteristics of nanoscale structures had enabled new applications in different fields in science and technology. Our capability to fabricate these nanostructures routinely for sure will impact the advancement of nanoscience. Apart from the high volume manufacturing in semiconductor industry, a small-scale but reliable nanofabrication tool can dramatically help the research in the field of nanotechnology. This dissertation describes alternative extreme ultraviolet (EUV) lithography techniques which combine table-top EUV laser and various cost-effective imaging strategies. For each technique, numerical simulations, system design, experiment result and its analysis will be presented. In chapter II, a brief review of the main characteristics of table-top EUV lasers will be addressed concentrating on its high power and large coherence radius that enable the lithography application described herein. The development of a Talbot EUV lithography system which is capable of printing 50nm half pitch nanopatterns will be illustrated in chapter III. A detailed discussion of its resolution limit will be presented followed by the development of X-Y-Z positioning stage, the fabrication protocol for diffractive EUV mask, and the pattern transfer using self- developed ion beam etching, and the dose control unit. In addition, this dissertation demonstrated the capability to fabricate functional periodic nanostructures using Talbot EUV lithography. After that, resolution enhancement techniques like multiple exposure, displacement Talbot EUV lithography, fractional Talbot EUV lithography, and Talbot lithography using 18.9nm amplified spontaneous emission laser will be demonstrated. Chapter IV will describe a hybrid EUV lithography which combines the Talbot imaging and interference lithography rendering a high resolution interference pattern whose lattice is modified by a custom designed Talbot mask. In other words, this method enables filling the arbitrary Talbot cell with ultra-fine interference nanofeatures. Detailed optics modeling, system design and experiment results using He-Ne laser and table top EUV laser are included. The last part of chapter IV will analyze its exclusive advantages over traditional Talbot or interference lithography.

A multi-wavelength fiber-optic temperature-controlled laser soldering system for upper aerodigestive tract reconstruction: an animal model.

PubMed

Abergel, Avraham; Gabay, Ilan; Fliss, Dan M; Katzir, Abraham; Gil, Ziv

2011-06-01

Laser soldering of a thick multilayer organ using conventional CO(2) lasers is ineffective. The purpose of this work was to develop a method for bonding the multilayer tissue of the upper aerodigestive tracts (UADT) without the need of sutures or stapling. Animal model. Academic research laboratory. The authors developed a multi-wavelength laser system, based on 2 fiber-optic lasers applied simultaneously. A highly absorbable CO(2) laser interacts with the muscular layer, and a nonabsorbable GaAs laser interacts with indocyanine-green solid albumin, placed between the mucosa and the muscular layer. The authors used an ex vivo porcine model to examine the capability of this system to effectively correct esophageal tears. The soldered esophagi burst pressure was >175 cm H(2)O (98% success rate) in 88 of the 90 experiments. A conventional CO(2) laser soldering resulted in insufficient bonding (mean burst pressure of 40 ± 7 cm H(2)O, n = 5), while the multi-wavelength laser system provided an ~9-fold tighter seal (359 ± 75.4 cm H(2)O, P < .0001, n = 15). Burst pressures after conventional suturing of the defect was significantly lower (106 ± 65.8 cm H(2)O, P < .001) than in the multi-wavelength laser system. Bonding of the UADT mucosa using a multi-wavelength, temperature-controlled laser soldering system can support significantly higher pressures then conventional CO(2) laser soldering and suture repair. The mean bonding pressure was 3.5-fold higher than the maximal swallowing pressure. Our findings provide a basis for implementation of new surgical tools for repair of esophageal perforations.

Sample analysis at Mars

NASA Astrophysics Data System (ADS)

Coll, P.; Cabane, M.; Mahaffy, P. R.; Brinckerhoff, W. B.; Sam Team

The next landed missions to Mars, such as the planned Mars Science Laboratory and ExoMars, will require sample analysis capabilities refined well beyond what has been flown to date. A key science objective driving this requirement is the determination of the carbon inventory of Mars, and particularly the detection of organic compounds. The Sample Analysis at Mars (SAM) suite consists of a group of tightly-integrated experiments that would analyze samples delivered directly from a coring drill or by a facility sample processing and delivery (SPAD) mechanism. SAM consists of an advanced GC/MS system and a laser desorption mass spectrometer (LDMS). The combined capabilities of these techniques can address Mars science objectives with much improved sensitivity, resolution, and analytical breadth over what has been previously possible in situ. The GC/MS system analyzes the bulk composition (both molecular and isotopic) of solid-phase and atmospheric samples. Solid samples are introduced with a highly flexible chemical derivatization/pyrolysis subsystem (Pyr/GC/MS) that is significantly more capable than the mass spectrometers on Viking. The LDMS analyzes local elemental and molecular composition in solid samples vaporized and ionized with a pulsed laser. We will describe how each of these capabilities has particular strengths that can achieve key measurement objectives at Mars. In addition, the close codevelopment of the GC/MS and LDMS along with a sample manipulation system enables the the sharing of resources, the correlation of results, and the utilization of certain approaches that would not be possible with separate instruments. For instance, the same samples could be analyzed with more than one technique, increasing efficiency and providing cross-checks for quantification. There is also the possibility of combining methods, such as by permitting TOF-MS analyses of evolved gas (Pyr/EI-TOF-MS) or GC/MS analyses of laser evaporated gas (LD-GC/MS).

Laser driving and data processing concept for mobile trace gas sensing: Design and implementation

NASA Astrophysics Data System (ADS)

Liu, Chang; Tuzson, Béla; Scheidegger, Philipp; Looser, Herbert; Bereiter, Bernhard; Graf, Manuel; Hundt, Morten; Aseev, Oleg; Maas, Deran; Emmenegger, Lukas

2018-06-01

High precision mobile sensing of multi-species gases is greatly demanded in a wide range of applications. Although quantum cascade laser absorption spectroscopy demonstrates excellent field-deployment capabilities for gas sensing, the implementation of this measurement technique into sensor-like portable instrumentation still remains challenging. In this paper, two crucial elements, the laser driving and data acquisition electronics, are addressed. Therefore, we exploit the benefits of the time-division multiplexed intermittent continuous wave driving concept and the real-time signal pre-processing capabilities of a commercial System-on-Chip (SoC, Red Pitaya). We describe a re-designed current driver that offers a universal solution for operating a wide range of multi-wavelength quantum cascade laser device types and allows stacking for the purpose of multiple laser configurations. Its adaptation to the various driving situations is enabled by numerous field programmable gate array (FPGA) functionalities that were developed on the SoC, such as flexible generation of a large variety of synchronized trigger signals and digital inputs/outputs (DIOs). The same SoC is used to sample the spectroscopic signal at rates up to 125 MS/s with 14-bit resolution. Additional FPGA functionalities were implemented to enable on-board averaging of consecutive spectral scans in real-time, resulting in optimized memory bandwidth and hardware resource utilisation and autonomous system operation. Thus, we demonstrate how a cost-effective, compact, and commercial SoC can successfully be adapted to obtain a fully operational research-grade laser spectrometer. The overall system performance was examined in a spectroscopic setup by analyzing low pressure absorption features of CO2 at 4.3 μm.

Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing.

PubMed

Borri, Simone; Siciliani de Cumis, Mario; Insero, Giacomo; Bartalini, Saverio; Cancio Pastor, Pablo; Mazzotti, Davide; Galli, Iacopo; Giusfredi, Giovanni; Santambrogio, Gabriele; Savchenkov, Anatoliy; Eliyahu, Danny; Ilchenko, Vladimir; Akikusa, Naota; Matsko, Andrey; Maleki, Lute; De Natale, Paolo

2016-02-17

The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF₂ microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line.

Deep learning and model predictive control for self-tuning mode-locked lasers

NASA Astrophysics Data System (ADS)

Baumeister, Thomas; Brunton, Steven L.; Nathan Kutz, J.

2018-03-01

Self-tuning optical systems are of growing importance in technological applications such as mode-locked fiber lasers. Such self-tuning paradigms require {\\em intelligent} algorithms capable of inferring approximate models of the underlying physics and discovering appropriate control laws in order to maintain robust performance for a given objective. In this work, we demonstrate the first integration of a {\\em deep learning} (DL) architecture with {\\em model predictive control} (MPC) in order to self-tune a mode-locked fiber laser. Not only can our DL-MPC algorithmic architecture approximate the unknown fiber birefringence, it also builds a dynamical model of the laser and appropriate control law for maintaining robust, high-energy pulses despite a stochastically drifting birefringence. We demonstrate the effectiveness of this method on a fiber laser which is mode-locked by nonlinear polarization rotation. The method advocated can be broadly applied to a variety of optical systems that require robust controllers.

Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing

PubMed Central

Borri, Simone; Siciliani de Cumis, Mario; Insero, Giacomo; Bartalini, Saverio; Cancio Pastor, Pablo; Mazzotti, Davide; Galli, Iacopo; Giusfredi, Giovanni; Santambrogio, Gabriele; Savchenkov, Anatoliy; Eliyahu, Danny; Ilchenko, Vladimir; Akikusa, Naota; Matsko, Andrey; Maleki, Lute; De Natale, Paolo

2016-01-01

The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF2 microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line. PMID:26901199

Space Applications Industrial Laser System (SAILS)

NASA Technical Reports Server (NTRS)

Mccay, T. D.; Bible, J. B.; Mueller, R. E.

1993-01-01

A program is underway to develop a YAG laser based materials processing workstation to fly in the cargo bay of the Space Shuttle. This workstation, called Space Applications Industrial Laser System (SAILS), will be capable of cutting and welding steel, aluminum, and Inconel alloys of the type planned for use in constructing the Space Station Freedom. As well as demonstrating the ability of a YAG laser to perform remote (fiber-optic delivered) repair and fabrication operations in space, fundamental data will be collected on these interactions for comparison with terrestrial data and models. The flight system, scheduled to fly in 1996, will be constructed as three modules using standard Get-Away-Special (GAS) canisters. The first module holds the laser head and cooling system, while the second contains a high peak power electrical supply. The third module houses the materials processing workstation and the command and data acquisition subsystems. The laser head and workstation cansisters are linked by a fiber-optic cable to transmit the laser light. The team assembled to carry out this project includes Lumonics Industrial Products (laser), Tennessee Technological University (structural analysis and fabrication), Auburn University Center for Space Power (electrical engineering), University of Waterloo (low-g laser process consulting), and CSTAR/UTSI (data acquisition, control, software, integration, experiment design). This report describes the SAILS program and highlights recent activities undertaken at CSTAR.

Diode pumped solid state kilohertz disk laser system for time-resolved combustion diagnostics under microgravity at the drop tower Bremen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wagner, Volker; Paa, Wolfgang; Triebel, Wolfgang

We describe a specially designed diode pumped solid state laser system based on the disk laser architecture for combustion diagnostics under microgravity (μg) conditions at the drop tower in Bremen. The two-stage oscillator-amplifier-system provides an excellent beam profile (TEM{sub 00}) at narrowband operation (Δλ < 1 pm) and is tunable from 1018 nm to 1052 nm. The laser repetition rate of up to 4 kHz at pulse durations of 10 ns enables the tracking of processes on a millisecond time scale. Depending on the specific issue it is possible to convert the output radiation up to the fourth harmonic aroundmore » 257 nm. The very compact laser system is integrated in a slightly modified drop capsule and withstands decelerations of up to 50 g (>11 ms). At first the concept of the two-stage disk laser is briefly explained, followed by a detailed description of the disk laser adaption to the drop tower requirements with special focus on the intended use under μg conditions. In order to demonstrate the capabilities of the capsule laser as a tool for μg combustion diagnostics, we finally present an investigation of the precursor-reactions before the droplet ignition using 2D imaging of the Laser Induced Fluorescence of formaldehyde.« less

Development and testing of laser Doppler system components for wake vortex monitoring. Volume 1: Scanner development, laboratory and field testing and system modeling

NASA Technical Reports Server (NTRS)

Wilson, D. J.; Krause, M. C.; Coffey, E. W.; Huang, C. C.; Edwards, B. B.; Shrider, K. R.; Jetton, J. L.; Morrison, L. K.

1974-01-01

A servo-controlled range/elevation scanner for the laser Doppler velocimeter (LDV) was developed and tested in the field to assess its performance in detecting and monitoring aircraft trailing vortices in an airport environment. The elevation scanner provides a capability to manually point the LDV telescope at operator chosen angles from 3.2 deg. to 89.6 deg within 0.2 deg, or to automatically scan the units between operator chosen limits at operator chosen rates of 0.1 Hz to 0.5 Hz. The range scanner provides a capability to manually adjust the focal point of the system from a range of 32 meters to a range of 896 meters under operator control, or to scan between operator chosen limits and at rates from 0.1 Hz to 6.9 Hz. The scanner controls are designed to allow simulataneous range and elevation scanning so as to provide finger scan patterns, arc scan patterns, and vertical line scan patterns. The development and testing of the unit is discussed, along with a fluid dynamic model of the wake vortex developed in a laser Doppler vortex sensor simulation program.

Practical application of cross correlation technique to measure jitter of master-oscillator-power-amplifier laser system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Młyńczak, J.; Sawicz-Kryniger, K.; Fry, A. R.

2014-01-01

The Linac coherent light source (LCLS) at the SLAC National Accelerator Laboratory (SLAC) is the world’s first hard X-ray free electron laser (XFEL) and is capable of producing high-energy, femtosecond duration X-ray pulses. A common technique to study fast timescale physical phenomena, various “pump/probe” techniques are used. In these techniques there are two lasers, one optical and one X-ray, that work as a pump and as a probe to study dynamic processes in atoms and molecules. In order to resolve phenomena that occur on femtosecond timescales, it is imperative to have very precise timing between the optical lasers and X-raysmore » (on the order of ~ 20 fs or better). The lasers are synchronized to the same RF source that drives the accelerator and produces the X-ray laser. However, elements in the lasers cause some drift and time jitter, thereby de-synchronizing the system. This paper considers cross-correlation technique as a way to quantify the drift and jitter caused by the regenerative amplifier of the ultrafast optical laser.« less

Modulated and continuous-wave operations of low-power thulium (Tm:YAP) laser in tissue welding

NASA Astrophysics Data System (ADS)

Bilici, Temel; Tabakoğlu, Haşim Özgür; Topaloğlu, Nermin; Kalaycıoğlu, Hamit; Kurt, Adnan; Sennaroglu, Alphan; Gülsoy, Murat

2010-05-01

Our aim is to explore the welding capabilities of a thulium (Tm:YAP) laser in modulated and continuous-wave (CW) modes of operation. The Tm:YAP laser system developed for this study includes a Tm:YAP laser resonator, diode laser driver, water chiller, modulation controller unit, and acquisition/control software. Full-thickness incisions on Wistar rat skin were welded by the Tm:YAP laser system at 100 mW and 5 s in both modulated and CW modes of operation (34.66 W/cm2). The skin samples were examined during a 21-day healing period by histology and tensile tests. The results were compared with the samples closed by conventional suture technique. For the laser groups, immediate closure at the surface layers of the incisions was observed. Full closures were observed for both modulated and CW modes of operation at day 4. The tensile forces for both modulated and CW modes of operation were found to be significantly higher than the values found by conventional suture technique. The 1980-nm Tm:YAP laser system operating in both modulated and CW modes maximizes the therapeutic effect while minimizing undesired side effects of laser tissue welding. Hence, it is a potentially important alternative tool to the conventional suturing technique.

Next generation diode lasers with enhanced brightness

NASA Astrophysics Data System (ADS)

Ried, S.; Rauch, S.; Irmler, L.; Rikels, J.; Killi, A.; Papastathopoulos, E.; Sarailou, E.; Zimer, H.

2018-02-01

High-power diode lasers are nowadays well established manufacturing tools in high power materials processing, mainly for tactile welding, surface treatment and cladding applications. Typical beam parameter products (BPP) of such lasers range from 30 to 50 mm·mrad at several kilowatts of output power. TRUMPF offers a product line of diode lasers to its customers ranging from 150 W up to 6 kW of output power. These diode lasers combine high reliability with small footprint and high efficiency. However, up to now these lasers are limited in brightness due to the commonly used spatial and coarse spectral beam combining techniques. Recently diode lasers with enhanced brightness have been presented by use of dense wavelength multiplexing (DWM). In this paper we report on TRUMPF's diode lasers utilizing DWM. We demonstrate a 2 kW and a 4 kW system ideally suited for fine welding and scanner welding applications. The typical laser efficiency is in the range of 50%. The system offers plug and play exchange of the fiber beam delivery cable, multiple optical outputs and integrated cooling in a very compact package. An advanced control system offers flexible integration in any customer's shop floor environment and includes industry 4.0 capabilities (e.g. condition monitoring and predictive maintenance).

Greenlite™: a year of carbon dioxide monitoring over paris, france, and recent progress in monitoring methane

NASA Astrophysics Data System (ADS)

Dobler, Jeremy; Zaccheo, T. Scott; Pernini, Timothy; Blume, Nathan; Braun, Michael

2018-04-01

GreenLITE™ is a ground-based laser absorption spectroscopy system capable of measuring and mapping CO2 concentrations over areas up to 25 km2. The system was deployed for COP21 as a demonstration and has now completed a year of CO2 measurements over the city of Paris, France. We will discuss lessons learned and relevant data from the year-long deployment. Recently, the system has demonstrated the same measurement capability for CH4, and results from preliminary testing are presented.

Molecular dispersion spectroscopy – new capabilities in laser chemical sensing

PubMed Central

Nikodem, Michal; Wysocki, Gerard

2012-01-01

Laser spectroscopic techniques suitable for molecular dispersion sensing enable new applications and strategies in chemical detection. This paper discusses the current state-of-the art and provides an overview of recently developed chirped laser dispersion spectroscopy (CLaDS) based techniques. CLaDS and its derivatives allow for quantitative spectroscopy of trace-gases and enable new capabilities such as extended dynamic range of concentration measurements, high immunity to photodetected intensity fluctuations, or capability of direct processing of spectroscopic signals in optical domain. Several experimental configurations based on quantum cascade lasers and examples of molecular spectroscopic data are presented to demonstrate capabilities of molecular dispersion spectroscopy in the mid-infrared spectral region. PMID:22809459

High-power fused assemblies enabled by advances in fiber-processing technologies

NASA Astrophysics Data System (ADS)

Wiley, Robert; Clark, Brett

2011-02-01

The power handling capabilities of fiber lasers are limited by the technologies available to fabricate and assemble the key optical system components. Previous tools for the assembly, tapering, and fusion of fiber laser elements have had drawbacks with regard to temperature range, alignment capability, assembly flexibility and surface contamination. To provide expanded capabilities for fiber laser assembly, a wide-area electrical plasma heat source was used in conjunction with an optimized image analysis method and a flexible alignment system, integrated according to mechatronic principles. High-resolution imaging and vision-based measurement provided feedback to adjust assembly, fusion, and tapering process parameters. The system was used to perform assembly steps including dissimilar-fiber splicing, tapering, bundling, capillary bundling, and fusion of fibers to bulk optic devices up to several mm in diameter. A wide range of fiber types and diameters were tested, including extremely large diameters and photonic crystal fibers. The assemblies were evaluated for conformation to optical and mechanical design criteria, such as taper geometry and splice loss. The completed assemblies met the performance targets and exhibited reduced surface contamination compared to assemblies prepared on previously existing equipment. The imaging system and image analysis algorithms provided in situ fiber geometry measurement data that agreed well with external measurement. The ability to adjust operating parameters dynamically based on imaging was shown to provide substantial performance benefits, particularly in the tapering of fibers and bundles. The integrated design approach was shown to provide sufficient flexibility to perform all required operations with a minimum of reconfiguration.

3D Laser Scanner for Underwater Manipulation.

PubMed

Palomer, Albert; Ridao, Pere; Youakim, Dina; Ribas, David; Forest, Josep; Petillot, Yvan

2018-04-04

Nowadays, research in autonomous underwater manipulation has demonstrated simple applications like picking an object from the sea floor, turning a valve or plugging and unplugging a connector. These are fairly simple tasks compared with those already demonstrated by the mobile robotics community, which include, among others, safe arm motion within areas populated with a priori unknown obstacles or the recognition and location of objects based on their 3D model to grasp them. Kinect-like 3D sensors have contributed significantly to the advance of mobile manipulation providing 3D sensing capabilities in real-time at low cost. Unfortunately, the underwater robotics community is lacking a 3D sensor with similar capabilities to provide rich 3D information of the work space. In this paper, we present a new underwater 3D laser scanner and demonstrate its capabilities for underwater manipulation. In order to use this sensor in conjunction with manipulators, a calibration method to find the relative position between the manipulator and the 3D laser scanner is presented. Then, two different advanced underwater manipulation tasks beyond the state of the art are demonstrated using two different manipulation systems. First, an eight Degrees of Freedom (DoF) fixed-base manipulator system is used to demonstrate arm motion within a work space populated with a priori unknown fixed obstacles. Next, an eight DoF free floating Underwater Vehicle-Manipulator System (UVMS) is used to autonomously grasp an object from the bottom of a water tank.

Robust holographic storage system design.

PubMed

Watanabe, Takahiro; Watanabe, Minoru

2011-11-21

Demand is increasing daily for large data storage systems that are useful for applications in spacecraft, space satellites, and space robots, which are all exposed to radiation-rich space environment. As candidates for use in space embedded systems, holographic storage systems are promising because they can easily provided the demanded large-storage capability. Particularly, holographic storage systems, which have no rotation mechanism, are demanded because they are virtually maintenance-free. Although a holographic memory itself is an extremely robust device even in a space radiation environment, its associated lasers and drive circuit devices are vulnerable. Such vulnerabilities sometimes engendered severe problems that prevent reading of all contents of the holographic memory, which is a turn-off failure mode of a laser array. This paper therefore presents a proposal for a recovery method for the turn-off failure mode of a laser array on a holographic storage system, and describes results of an experimental demonstration. © 2011 Optical Society of America

Final Report: Laser-Based Optical Trap for Remote Sampling of Interplanetary and Atmospheric Particulate Matter

NASA Technical Reports Server (NTRS)

Stysley, Paul

2016-01-01

Applicability to Early Stage Innovation NIAC Cutting edge and innovative technologies are needed to achieve the demanding requirements for NASA origin missions that require sample collection as laid out in the NRC Decadal Survey. This proposal focused on fully understanding the state of remote laser optical trapping techniques for capturing particles and returning them to a target site. In future missions, a laser-based optical trapping system could be deployed on a lander that would then target particles in the lower atmosphere and deliver them to the main instrument for analysis, providing remote access to otherwise inaccessible samples. Alternatively, for a planetary mission the laser could combine ablation and trapping capabilities on targets typically too far away or too hard for traditional drilling sampling systems. For an interstellar mission, a remote laser system could gather particles continuously at a safe distance; this would avoid the necessity of having a spacecraft fly through a target cloud such as a comet tail. If properly designed and implemented, a laser-based optical trapping system could fundamentally change the way scientists designand implement NASA missions that require mass spectroscopy and particle collection.

Laser Communication Demonstration System (LCDS) and future mobile satellite services

NASA Technical Reports Server (NTRS)

Chen, Chien-Chung; Wilhelm, Michael D.; Lesh, James R.

1995-01-01

The Laser Communications Demonstration System (LCDS) is a proposed in-orbit demonstration of high data rate laser communications technology conceived jointly by NASA and U.S. industry. The program objectives are to stimulate industry development and to demonstrate the readiness of high data rate optical communications in Earth orbit. For future global satellite communication systems using intersatellite links, laser communications technology can offer reduced mass and power requirements and higher channel bandwidths without regulatory constraints. As currently envisioned, LCDS will consist of one or two orbiting laser communications terminals capable of demonstrating high data rate (greater than 750Mbps) transmission in a dynamic space environment. Two study teams led by Motorola and Ball Aerospace are currently in the process of conducting a Phase A/B mission definition study of LCDS under contracts with JPL/NASA. The studies consist of future application survey, concept and requirements definition, and a point design of the laser communications flight demonstration. It is planned that a single demonstration system will be developed based on the study results. The Phase A/B study is expected to be completed by the coming June, and the current results of the study are presented in this paper.

High volume fabrication of laser targets using MEMS techniques

NASA Astrophysics Data System (ADS)

Spindloe, C.; Arthur, G.; Hall, F.; Tomlinson, S.; Potter, R.; Kar, S.; Green, J.; Higginbotham, A.; Booth, N.; Tolley, M. K.

2016-04-01

The latest techniques for the fabrication of high power laser targets, using processes developed for the manufacture of Micro-Electro-Mechanical System (MEMS) devices are discussed. These laser targets are designed to meet the needs of the increased shot numbers that are available in the latest design of laser facilities. Traditionally laser targets have been fabricated using conventional machining or coarse etching processes and have been produced in quantities of 10s to low 100s. Such targets can be used for high complexity experiments such as Inertial Fusion Energy (IFE) studies and can have many complex components that need assembling and characterisation with high precision. Using the techniques that are common to MEMS devices and integrating these with an existing target fabrication capability we are able to manufacture and deliver targets to these systems. It also enables us to manufacture novel targets that have not been possible using other techniques. In addition, developments in the positioning systems that are required to deliver these targets to the laser focus are also required and a system to deliver the target to a focus of an F2 beam at 0.1Hz is discussed.

Laser Propulsion for LOTV Space Missions

NASA Astrophysics Data System (ADS)

Rezunkov, Yuri A.

2004-03-01

Advanced Space Propulsion-Investigation Committee (ASPIC) of the Japan Society for Aeronautics and Space Sciences (JSASS) selected the Laser Orbital Transfer Vehicle (LOTV) project for development of non-chemical space propulsion systems that have a capability to sustain expanded human space activities in the 21st century. This talk is presenting an analysis of the laser propulsion researches made within the frames of the ISTC Project 1801 as applied to the LOTV Project. The study includes the development of techniques for low-thrust maneuvers of the spacecraft to achieve geostationary orbits.

High-speed pre-clinical brain imaging using pulsed laser diode based photoacoustic tomography (PLD-PAT) system

NASA Astrophysics Data System (ADS)

Upputuri, Paul Kumar; Pramanik, Manojit

2016-03-01

Photoacoustic tomography (PAT) is a promising biomedical imaging modality for small animal imaging, breast cancer imaging, monitoring of vascularisation, tumor angiogenesis, blood oxygenation, total haemoglobin concentration etc. The existing PAT systems that uses Q-switched Nd:YAG and OPO nanosecond lasers have limitations in clinical applications because they are expensive, non-potable and not suitable for real-time imaging due to their low pulse repetition rate. Low-energy pulsed near-infrared diode laser which are low-cost, compact, and light-weight (<200 grams), can be used as an alternate. In this work, we present a photoacoustic tomography system with a pulsed laser diode (PLD) that can nanosecond pulses with pulse energy 1.3 mJ/pulse at ~803 nm wavelength and 7000 Hz repetition rate. The PLD is integrated inside a single-detector circular scanning geometric system. To verify the high speed imaging capabilities of the PLD-PAT system, we performed in vivo experimental results on small animal brain imaging using this system. The proposed system is portable, low-cost and can provide real-time imaging.

A pulse-burst laser system for Thomson scattering on NSTX-U

NASA Astrophysics Data System (ADS)

Den Hartog, D. J.; Borchardt, M. T.; Holly, D. J.; Diallo, A.; LeBlanc, B.

2017-10-01

A pulse-burst laser system has been built for Thomson scattering on NSTX-U, and is currently being integrated into the NSTX-U Thomson scattering diagnostic system. The laser will be operated in three distinct modes. The base mode is continuous 30 Hz rep rate, and is the standard operating mode of the laser. The base mode will be interrupted to produce a "slow burst" (specified 1 kHz rep rate for 50 ms) or a "fast burst" (specified 10 kHz rep rate for 5 ms). The combination of base mode→ interruption→ burst mode is new and has not been implemented on any previous pulse-burst laser system. Laser pulsing is halted for a set period (~ 1 minute) following a burst to allow the YAG rods to cool; this type of operation is called a heat-capacity laser. The laser is Nd:YAG operated at 1064 nm, q-switched to produce >= 1.5 J pulses with ~ 20 ns FWHM. It is flashlamp pumped, with dual-rod oscillator (9 mm) and dual-rod amplifier (12 mm). Variable pulsewidth drive of the flashlamps is accomplished by IGBT (insulated gate bipolar transistor) switching of electrolytic capacitor banks. Direct control of the laser Pockels cell drive enables optimal pulse energy extraction. The laser system has demonstrated compliance with all specifications, and is capable of exceeding design specifications by significant margins, e.g., higher rep rates for longer burst periods. Burst operation of this laser system will be used to capture fast time evolution of the electron temperature and density profiles during events such as ELMs, the L-H transition, and various MHD modes.

Performance comparison of supersonic ejectors with different motive gas injection schemes applicable for flowing medium gas laser

NASA Astrophysics Data System (ADS)

Singhal, G.; Subbarao, P. M. V.; Mainuddin; Tyagi, R. K.; Dawar, A. L.

2017-05-01

A class of flowing medium gas lasers with low generator pressures employ supersonic flows with low cavity pressure and are primarily categorized as high throughput systems capable of being scaled up to MW class. These include; Chemical Oxygen Iodine Laser (COIL) and Hydrogen (Deuterium) Fluoride (HF/DF). The practicability of such laser systems for various applications is enhanced by exhausting the effluents directly to ambient atmosphere. Consequently, ejector based pressure recovery forms a potent configuration for open cycle operation. Conventionally these gas laser systems require at least two ejector stages with low pressure stage being more critical, since it directly entrains the laser media, and the ensuing perturbation of cavity flow, if any, may affect laser operation. Hence, the choice of plausible motive gas injection schemes viz., peripheral or central is a fluid dynamic issue of interest, and a parametric experimental performance comparison would be beneficial. Thus, the focus is to experimentally characterize the effect of variation in motive gas supply pressure, entrainment ratio, back pressure conditions, nozzle injection position operated together with a COIL device and discern the reasons for the behavior.

Microscope self-calibration based on micro laser line imaging and soft computing algorithms

NASA Astrophysics Data System (ADS)

Apolinar Muñoz Rodríguez, J.

2018-06-01

A technique to perform microscope self-calibration via micro laser line and soft computing algorithms is presented. In this technique, the microscope vision parameters are computed by means of soft computing algorithms based on laser line projection. To implement the self-calibration, a microscope vision system is constructed by means of a CCD camera and a 38 μm laser line. From this arrangement, the microscope vision parameters are represented via Bezier approximation networks, which are accomplished through the laser line position. In this procedure, a genetic algorithm determines the microscope vision parameters by means of laser line imaging. Also, the approximation networks compute the three-dimensional vision by means of the laser line position. Additionally, the soft computing algorithms re-calibrate the vision parameters when the microscope vision system is modified during the vision task. The proposed self-calibration improves accuracy of the traditional microscope calibration, which is accomplished via external references to the microscope system. The capability of the self-calibration based on soft computing algorithms is determined by means of the calibration accuracy and the micro-scale measurement error. This contribution is corroborated by an evaluation based on the accuracy of the traditional microscope calibration.

Laser Direct Routing for High Density Interconnects

NASA Astrophysics Data System (ADS)

Moreno, Wilfrido Alejandro

The laser restructuring of electronic circuits fabricated using standard Very Large Scale Integration (VLSI) process techniques, is an excellent alternative that allows low-cost quick turnaround production with full circuit similarity between the Laser Restructured prototype and the customized product for mass production. Laser Restructurable VLSI (LRVLSI) would allow design engineers the capability to interconnect cells that implement generic logic functions and signal processing schemes to achieve a higher level of design complexity. LRVLSI of a particular circuit at the wafer or packaged chip level is accomplished using an integrated computer controlled laser system to create low electrical resistance links between conductors and to cut conductor lines. An infrastructure for rapid prototyping and quick turnaround using Laser Restructuring of VLSI circuits was developed to meet three main parallel objectives: to pursue research on novel interconnect technologies using LRVLSI, to develop the capability of operating in a quick turnaround mode, and to maintain standardization and compatibility with commercially available equipment for feasible technology transfer. The system is to possess a high degree of flexibility, high data quality, total controllability, full documentation, short downtime, a user-friendly operator interface, automation, historical record keeping, and error indication and logging. A specially designed chip "SLINKY" was used as the test vehicle for the complete characterization of the Laser Restructuring system. With the use of Design of Experiment techniques the Lateral Diffused Link (LDL), developed originally at MIT Lincoln Laboratories, was completely characterized and for the first time a set of optimum process parameters was obtained. With the designed infrastructure fully operational, the priority objective was the search for a substitute for the high resistance, high current leakage to substrate, and relatively low density Lateral Diffused Link. A high density Laser Vertical Link with resistance values below 10 ohms was developed, studied and tested using design of experiment methodologies. The vertical link offers excellent advantages in the area of quick prototyping of electronic circuits, but even more important, due to having similar characteristics to a foundry produced via, it gives quick transfer from the prototype system verification stage to the mass production stage.

Corneal reshaping using a pulsed UV solid-state laser

NASA Astrophysics Data System (ADS)

Ren, Qiushi; Simon, Gabriel; Parel, Jean-Marie A.; Shen, Jin-Hui; Takesue, Yoshiko

1993-06-01

Replacing the gas ArF (193 nm) excimer laser with a solid state laser source in the far-UV spectrum region would eliminate the hazards of a gas laser and would reduce its size which is desirable for photo-refractive keratectomy (PRK). In this study, we investigated corneal reshaping using a frequency-quintupled (213 nm) pulsed (10 ns) Nd:YAG laser coupled to a computer-controlled optical scanning delivery system. Corneal topographic measurements showed myopic corrections ranging from 2.3 to 6.1 diopters. Post-operative examination with the slit-lamp and operating microscope demonstrated a smoothly ablated surface without corneal haze. Histological results showed a smoothly sloping surface without recognizable steps. The surface quality and cellular effects were similar to that of previously described excimer PRK. Our study demonstrated that a UV solid state laser coupled to an optical scanning delivery system is capable of reshaping the corneal surface with the advantage of producing customized, aspheric corrections without corneal haze which may improve the quality of vision following PRK.

Standoff laser-based spectroscopy for explosives detection

NASA Astrophysics Data System (ADS)

Gaft, M.; Nagli, L.

2007-10-01

Real time detection and identification of explosives at a standoff distance is a major issue in efforts to develop defense against so-called Improvised Explosive Devices (IED). It is recognized that the only technique, which is potentially capable to standoff detection of minimal amounts of explosives is laser-based spectroscopy. LDS activity is based on a combination of laser-based spectroscopic methods with orthogonal capabilities. Our technique belongs to trace detection, namely to its micro-particles variety. It is based on commonly held belief that surface contamination was very difficult to avoid and could be exploited for standoff detection. We has applied optical techniques including gated Raman and time-resolved luminescence spectroscopy for detection of main explosive materials, both factory and homemade. We developed and tested a Raman system for the field remote detection and identification of minimal amounts of explosives on relevant surfaces at a distance of up to 30 meters.

A method of atmospheric density measurements during Shuttle entry using UV laser Rayleigh scattering

NASA Technical Reports Server (NTRS)

Mckenzie, Robert L.

1987-01-01

A detailed study is described of the performance capabilities and the hardware requirements for a method in which ambient density is measured along the Space Shuttle flight path using on-board optical instrumentation. The technique relies on Rayleigh scattering of light from a pulsed, ultraviolet, ArF excimer laser operating at a wavelength of 193 nm. The method is shown to be capable of providing direct measurements of ambient density with an uncertainty of less than 1 percent and with a spatial resolution of 1 km, over an altitude range from 50 to 90 km. In addition, extensions of this concept are discussed that allow measurements of the shock wave location and the density profile within the shock layer. Two approaches are identified that appear to be feasible, in which the same laser system is used for the extended measurements as that required for the ambient density measurements.

High-brightness displays in integrated weapon sight systems

NASA Astrophysics Data System (ADS)

Edwards, Tim; Hogan, Tim

2014-06-01

In the past several years Kopin has demonstrated the ability to provide ultra-high brightness, low power display solutions in VGA, SVGA, SXGA and 2k x 2k display formats. This paper will review various approaches for integrating high brightness overlay displays with existing direct view rifle sights and augmenting their precision aiming and targeting capability. Examples of overlay display systems solutions will be presented and discussed. This paper will review significant capability enhancements that are possible when augmenting the real-world as seen through a rifle sight with other soldier system equipment including laser range finders, ballistic computers and sensor systems.

Design and construction of a multiple beam laser projector and dynamically refocused wavefront sensor

NASA Astrophysics Data System (ADS)

Stalcup, Thomas Eugene, Jr.

Adaptive optics using natural guide stars can produce images of amazing quality, but is limited to a small fraction of the sky due to the need for a relatively bright guidestar. Adaptive optics systems using a laser generated artificial reference can be used over a majority of the sky, but these systems have some attendant problems. These problems can be reduced by increasing the altitude of the laser return, and indeed a simple, single laser source focused at an altitude of 95 km on a layer of atmospheric sodium performs well for the current generation of 8--10 m telescopes. For future giant telescopes in the 20--30 m class, however, the errors due to incorrect atmospheric sampling and spot elongation will prohibit such a simple system from working. The system presented in this dissertation provides a solution to these problems. Not only does it provide the 6.5m MMT with a relatively inexpensive laser guide star system with unique capabilities, it allows research into solving many of the problems faced by laser guide star systems on future giant telescopes. The MMT laser guidestar system projects a constellation of five doubled Nd:YAG laser beams focused at a mean height of 25 km, with a dynamic refocus system that corrects for spot elongation and allows integrating the return from a 10 km long range gate. It has produced seeing limited spot sizes in ˜1 arcsecond seeing conditions, and has enabled the first on-sky results of Ground Layer Adaptive Optics (GLAO).

TMD detection and tracking using improved AWACS sensors

NASA Astrophysics Data System (ADS)

Petersen, Steve; Kinashi, Yasuhiro; Leslie, Daniel

1995-01-01

This paper identifies an UOES (User Operational Evaluation Systems) version of an airborne surveillance sensor funded by the BMDO (Ballistic Missile Defense Organization). The sensors will be integrated into an operational AWACS E-3 upgrade program. This BMDO program initiative is called Extended Airborne Global Launch Evaluator, or EAGLE. Initial Operational Capability (IOC) of the EAGLE system will be ready in time to support the THAAD/GBR UOES capability. This airborne system, when developed, will consist of a passive infrared surveillance sensor (IRSS) with an active laser-ranger, on board an upgraded AWACS E3 aircraft to operate effectively in the TMD (theater missile defense) mission. The objective for the EAGLE is to field, in a reasonably short time and at a relatively low cost, a cueing sensor capability in regional conflicts to augment the existing space-based surveillance systems. With autonomous surveillance capability to search a wide-sector field, the EAGLE can detect and track boosting TBM's shortly after launch or as they break the clouds. Its passive IR sensor can also detect and track warm hardbody targets. Together with its laser-ranger, it is able to determine, immediately after the booster burn-out, very precise target state vectors that are accurate enough to predict their eventual impact points, to cue fire control radars, and to engage the weapons, if needed. Its primary TMD mission is to provide precise cueing of fire control radars to initiate the active defense weapon systems. Accurate cues from the EAGLE will off load radar resources to enable earlier detection of the targets at longer extended ranges, thereby increasing the interceptor battlespace for potentially more effective defense engagements and opportunities. It can also provide a precise early warning message to enable immediate TBM attack assessment and appropriate selection of defense engagement options by the battle manager. The functions of the sensor suite can be distributed, such that it can be tasked independently to observe the threat intercept, while providing continuous surveillance of new TBM launches, to support the kill assessment function for shoot-look-shoot opportunities. Another potential function that can be performed by the EAGLE is the estimation of TMD launch points (LPE) for counterforce support. This technical paper provides an expanded discussion of the EAGLE's mission roles, specific system functions, and its detection and tracking performance capability. The paper also addresses the sensor and the laser subsystem design characteristics and operational modes required to accomplish all its functions. Initial analyses indicate that the impact of scattering and absorption of the IR signatures and laser signals will be minimal on the performance of the system. Recent satellite data provides measurement of atmospheric extinction.

Feasibility of wake vortex monitoring systems for air terminals

NASA Technical Reports Server (NTRS)

Wilson, D. J.; Shrider, K. R.; Lawrence, T. R.

1972-01-01

Wake vortex monitoring systems, especially those using laser Doppler sensors, were investigated. The initial phases of the effort involved talking with potential users (air traffic controllers, pilots, etc.) of a wake vortex monitoring system to determine system requirements from the user's viewpoint. These discussions involved the volumes of airspace to be monitored for vortices, and potential methods of using the monitored vortex data once the data are available. A subsequent task led to determining a suitable mathematical model of the vortex phenomena and developing a mathematical model of the laser Doppler sensor for monitoring the vortex flow field. The mathematical models were used in combination to help evaluate the capability of laser Doppler instrumentation in monitoring vortex flow fields both in the near vicinity of the sensor (within 1 kilometer and at long ranges(10 kilometers).

Laser interferometric system for six-axis motion measurement.

PubMed

Zhang, Zhipeng; Menq, Chia-Hsiang

2007-08-01

This article presents the development of a precision laser interferometric system, which is designed to achieve six-axis motion measurement for real-time applications. By combining the advantage of the interferometer with a retroreflector and that of the interferometer with a plane mirror reflector, the system is capable of simultaneously measuring large transverse motions along and large rotational motions about three orthogonal axes. Based on optical path analysis along with the designed kinematics of the system, a closed form relationship between the six-axis motion parameters of the object being measured and the readings of the six laser interferometers is established. It can be employed as a real-time motion sensor for various six-axis motion control stages. A prototype is implemented and integrated with a six-axis magnetic levitation stage to illustrate its resolution and measurement range.

Measurement of remote micro vibration based on laser feedback interference

NASA Astrophysics Data System (ADS)

Wu, Peng; Qin, Shuijie; Xu, Ning

2018-03-01

The method of remote micro-vibration measurement is studied and presented based on the laser feedback effect in this paper, and the key factors of remote vibration measurement are analyzed. The vibration measurement system is designed and built based on the laser feedback and the research of the remote micro vibration measurement is carried out. The system has ultrahigh measuring sensitivity and the working distance is 25 meters, which can measure the vibration of non-cooperative target. The system has the capability to realize the non-contact measurement of remote micro-vibration at different driving signals and can fulfill the complex vibration measurement and reproduction of multiple frequencies. It can identify the voice signal and the voice signal reproduced is clear to hear. The system can meet various requirements of vibration measurement and has great significance in practical application.

Initial Demonstration of Mercury Wavefront Correction System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liao, Z M

2006-02-01

High average power operation of the Mercury Laser induces dynamic aberrations to the laser beam wavefront. Analysis of recent data indicates that up to 4 waves of low order aberration (mainly focus error or power, with spatial resolution < 0.5 cm{sup -1}) could be expected at each pass. Because of the magnitude of the wavefront error, the logical position is to place a deformable mirror (DM) at the M11 position, where the DM will correct the beam between passes 1 & 2 and 3 & 4. Currently, there are only two established commercial vendors offering complete adaptive optic (AO) systemsmore » that can accommodate the Mercury beam size (45 x 75 mm) which are compatible with high damage threshold coatings. Xinetics (MA, USA) offers a complete AO system along with a Shack-Hartmann wavefront sensor. The Xinetics DM is based on lead magnesium niobate (PMN) technology. A number of US aerospace firms as well as NIF use Xinetics PMN technology for their DMs. Phasics (Paris, France) offers a complete AO solution with its proprietary SID-4, a four-way shearing interferometric wavefront sensor capable of high resolution (over 100 x 100 sampling points). The Phasics system includes a bimorph deformable mirror from Night-n-Opt (Moscow, Russia) that uses lead zirconate titanate (PZT) technology. Various high power laser laboratories around the world such as LULI (France), HELEN (UK), and GEKKO (Japan) are using the PZT-based bimorph DM in their system. While both DM technologies are equivalent and have been deployed in high-energy laser systems, the PZT based bimorph DM offers two distinct features that makes it more attractive for high average power laser systems. The bimorph DM uses two layers of PZT actuators with the outer layer acting as power correctors, capable of correcting up to 20 waves of power. The Xinetics DM offers a maximum stroke of 4 waves. In addition, Night-N-Opt has also designed a water-cooled DM with a silicon based substrate (as opposed to a glass substrate) specifically for high average power laser systems--an option that is currently not available for PMN based DMs.« less

High-energy laser weapons: technology overview

NASA Astrophysics Data System (ADS)

Perram, Glen P.; Marciniak, Michael A.; Goda, Matthew

2004-09-01

High energy laser (HEL) weapons are ready for some of today"s most challenging military applications. For example, the Airborne Laser (ABL) program is designed to defend against Theater Ballistic Missiles in a tactical war scenario. Similarly, the Tactical High Energy Laser (THEL) program is currently testing a laser to defend against rockets and other tactical weapons. The Space Based Laser (SBL), Advanced Tactical Laser (ATL) and Large Aircraft Infrared Countermeasures (LAIRCM) programs promise even greater applications for laser weapons. This technology overview addresses both strategic and tactical roles for HEL weapons on the modern battlefield and examines current technology limited performance of weapon systems components, including various laser device types, beam control systems, atmospheric propagation, and target lethality issues. The characteristics, history, basic hardware, and fundamental performance of chemical lasers, solid state lasers and free electron lasers are summarized and compared. The elements of beam control, including the primary aperture, fast steering mirror, deformable mirrors, wavefront sensors, beacons and illuminators will be discussed with an emphasis on typical and required performance parameters. The effects of diffraction, atmospheric absorption, scattering, turbulence and thermal blooming phenomenon on irradiance at the target are described. Finally, lethality criteria and measures of weapon effectiveness are addressed. The primary purpose of the presentation is to define terminology, establish key performance parameters, and summarize technology capabilities.

Fluid mechanics of fusion lasers. Final report, September 11, 1978-June 5, 1980

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shwartz, J; Kulkarny, V A; Ausherman, D A

1980-01-01

Flow loop components required to operate continuous-flow, repetitively-pulsed CO/sub 2/ and KrF laser drivers for ICF were identified and their performance requirements were specified. It was found that the laser flow loops can have a major effect on the laser beam quality and overall efficiency. The pressure wave suppressor was identified as the most critical flow loop component. The performance of vented side-wall suppressors was evaluated both analytically and experimentally and found capable of meeting the performance requirements of the CO/sub 2/ and KrF fusion lasers. All other laser flow loop components are essentially similar to those used in conventional,more » low speed wind tunnels and are therefore well characterized and can be readily incorporated into fusion laser flow systems designs.« less

Narrow bandwidth Laser-Plasma Accelerator driven Thomson photon source development

NASA Astrophysics Data System (ADS)

Geddes, C. G. R.; Tsai, H.-E.; Otero, G.; Liu, X.; van Tilborg, J.; Toth, Cs.; Vay, J.-L.; Lehe, R.; Schroeder, C. B.; Esarey, E.; Friedman, A.; Grote, D. P.; Leemans, W. P.

2017-10-01

Compact, high-quality photon sources at MeV energies can be provided by Thomson scattering of a laser from the electron beam of a Laser-Plasma Accelerator (LPA). Recent experiments and simulations demonstrate controllable LPAs in the energy range appropriate to MeV sources. Simulations indicate that high flux with narrow energy spread can be achieved via control of the scattering laser pulse shape and laser guiding, and that undesired background bremsstrahlung can be mitigated by plasma based deceleration of the electron beam after photon production. Construction of experiments and laser capabilities to combine these elements will be presented, along with initial operations, towards a compact photon source system. Work supported by US DOE NNSA DNN R&D and by Sc. HEP under contract DE-AC02-05CH11231.

Testing of the Geoscience Laser Altimeter System (GLAS) Prototype Loop Heat Pipe

NASA Technical Reports Server (NTRS)

Douglas, Donya; Ku, Jentung; Kaya, Tarik

1998-01-01

This paper describes the testing of the prototype loop heat pipe (LHP) for the Geoscience Laser Altimeter System (GLAS). The primary objective of the test program was to verify the loop's heat transport and temperature control capabilities under conditions pertinent to GLAS applications. Specifically, the LHP had to demonstrate a heat transport capability of 100 W, with the operating temperature maintained within +/-2K while the condenser sink was subjected to a temperature change between 273K and 283K. Test results showed that this loop heat pipe was more than capable of transporting the required heat load and that the operating temperature could be maintained within +/-2K. However, this particular integrated evaporator-compensation chamber design resulted in an exchange of energy between the two that affected the overall operation of the system. One effect was the high temperature the LHP was required to reach before nucleation would begin due to inability to control liquid distribution during ground testing. Another effect was that the loop had a low power start-up limitation of approximately 25 W. These Issues may be a concern for other applications, although it is not expected that they will cause problems for GLAS under micro-gravity conditions.

Emerging Technology Creator of Worlds

DTIC Science & Technology

2016-01-01

periencing even more profound uses. Artificial intelligence, brain inter- face, robotics, autonomous systems, biotechnology , lasers, hypersonics, and......capability to create customized medical treatments using biotechnology , particu- larly in treating certain types of cancer and a variety of other

Source technology as the foundation for modern infra-red counter measures (IRCM)

NASA Astrophysics Data System (ADS)

Grasso, Robert J.

2010-10-01

Protection of military aircraft from IR guided threats is paramount to ensure the survivability of aircrews, platforms, and to ensure mission success. At the foundation of all IRCM systems is the source; that component that provides the in-band radiant energy required for threat defeat. As such, source technology has evolved with IRCM technology to encompass the evolving systems architectures that encompass IRCM: 1) "Hot Brick" omni-directional sources; 2) arc lamps, and; 3) lasers. Lasers, as IRCM sources continue to evolve to meet the challenges of ever-evolving threats, superior techniques, economy of installation, and superior source technology. Lasers represent the single greatest advance in IRCM source technology and continue to evolve to meet ever more sophisticated threats. And have been used with great effect in all modern IRCM systems; evolving from frequency doubled CO2 lasers, to solid state lasers with OPOs, to semiconductor lasers including Quantum Cascade Lasers (QCLs); these last devices represent the latest advance in IRCM source technology offering all-band coverage, architectural simplicity, and economy of scale. While QCLs represent the latest advance in IRCM laser technology, fiber lasers show much promise in addressing multi-band operation as well as the ability to be coherently combined to achieve even greater output capability. Also, ultra-short pulse lasers are evolving to become practical for IRCM applications. Stay tuned ......

Field resonance propulsion concept

NASA Technical Reports Server (NTRS)

Holt, A. C.

1979-01-01

A propulsion concept was developed based on a proposed resonance between coherent, pulsed electromagnetic wave forms, and gravitational wave forms (or space-time metrics). Using this concept a spacecraft propulsion system potentially capable of galactic and intergalactic travel without prohibitive travel times was designed. The propulsion system utilizes recent research associated with magnetic field line merging, hydromagnetic wave effects, free-electron lasers, laser generation of megagauss fields, and special structural and containment metals. The research required to determine potential, field resonance characteristics and to evaluate various aspects of the spacecraft propulsion design is described.

Excimer laser decontamination

NASA Astrophysics Data System (ADS)

Sentis, Marc L.; Delaporte, Philippe C.; Marine, Wladimir; Uteza, Olivier P.

2000-04-01

The application of excimer laser ablation process to the decontamination of radioactive surfaces is discussed. This technology is very attractive because it allows to efficiently remove the contaminated particles without secondary waste production. To demonstrate the capability of such technology to efficiently decontaminate large area, we studied and developed a prototype which include a XeCl laser, an optical fiber delivery system and an ablated particles collection cell. The main physical processes taking place during UV laser ablation will be explained. The influence of laser wavelength, pulse duration and absorption coefficient of material will be discussed. Special studies have been performed to understand the processes which limit the transmission of high average power excimer laser through optical fiber, and to determine the laser conditions to optimize the value of this transmission. An in-situ spectroscopic analysis of laser ablation plasma allows the real time control of the decontamination. The results obtained for painting or metallic oxides removal from stainless steel surfaces will be presented.

A 3-component laser-Doppler velocimeter data acquisition and reduction system

NASA Technical Reports Server (NTRS)

Rodman, L. C.; Bell, J. H.; Mehta, R. D.

1986-01-01

This report describes a laser Doppler velocimeter capable of measuring all three components of velocity simultaneously in low-speed flows. All the mean velocities, Reynolds stresses, and higher-order products can then be evaluated. The approach followed is to split one of the colors used in a 2-D system, thus creating a third set of beams which is then focused in the flow from an off-axis direction. The third velocity component is computed from the known geometry of the system. In this report, the laser optical hardware and the data acquisition electronics are described in detail. In addition, full operating procedures and listings of the software (written in BASIC and assembly languages) are also included. Some typical measurements obtained with this system in a vortex/mixing layer interaction are presented and compared directly to those obtained with a cross-wire system.

A flexible master oscillator for a pulse-burst laser system

NASA Astrophysics Data System (ADS)

Den Hartog, D. J.; Young, W. C.

2015-12-01

A new master oscillator is being installed in the pulse-burst laser system used for high-rep-rate Thomson scattering on the MST experiment. This new master oscillator will enable pulse repetition rates up to 1 MHz, with the ability to program a burst of pulses with arbitrary and varying time separation between each pulse. In addition, the energy of each master oscillator pulse can be adjusted to compensate for gain variations in the power amplifier section of the laser system. This flexibility is accomplished by chopping a CW laser source with a high-bandwidth acousto-optic modulator (AOM). The laser source is a Laser Quantum ventus 1064 diode-pumped solid-state laser with continuous output power variable from 100 to 500 mW. The 1064 nm, 2.7 mm diameter polarized beam is focused into the gallium phosphide crystal of a Brimrose AOM, which deflects the beam by approximately 60 mR when driven by the 400 MHz fixed frequency driver. Beam deflection is controlled by a simple digital input pulse, and is capable of producing deflected pulses of less than 20 ns width at repetition rates much greater than 1 MHz. These deflected pulses from the output of the AOM are collimated and propagated into the laser amplifier system, where they will be amplified to ~ 2 J/pulse and injected into the MST plasma.

Excimer laser calibration system.

PubMed

Gottsch, J D; Rencs, E V; Cambier, J L; Hall, D; Azar, D T; Stark, W J

1996-01-01

Excimer laser photoablation for refractive and therapeutic keratectomies has been demonstrated to be feasible and practicable. However, corneal laser ablations are not without problems, including the delivery and maintenance of a homogeneous beam. We have developed an excimer laser calibration system capable of characterizing a laser ablation profile. Beam homogeneity is determined by the analysis of a polymethylmethacrylate (PMMA)-based thin-film using video capture and image processing. The ablation profile is presented as a color-coded map. Interpolation of excimer calibration system analysis provides a three-dimensional representation of elevation profiles that correlates with two-dimensional scanning profilometry. Excimer calibration analysis was performed before treating a monkey undergoing phototherapeutic keratectomy and two human subjects undergoing myopic spherocylindrical photorefractive keratectomy. Excimer calibration analysis was performed before and after laser refurbishing. Laser ablation profiles in PMMA are resolved by the excimer calibration system to .006 microns/pulse. Correlations with ablative patterns in a monkey cornea were demonstrated with preoperative and postoperative keratometry using corneal topography, and two human subjects using video-keratography. Excimer calibration analysis predicted a central-steep-island ablative pattern with the VISX Twenty/Twenty laser, which was confirmed by corneal topography immediately postoperatively and at 1 week after reepithelialization in the monkey. Predicted central steep islands in the two human subjects were confirmed by video-keratography at 1 week and at 1 month. Subsequent technical refurbishing of the laser resulted in a beam with an overall increased ablation rate measured as microns/pulse with a donut ablation profile. A patient treated after repair of the laser electrodes demonstrated no central island. This excimer laser calibration system can precisely detect laser-beam ablation profiles. The calibration system correctly predicted central islands after excimer photoablation in a treated monkey cornea and in two treated human subjects. Detection of excimer-laser-beam ablation profiles may be useful for precise calibration of excimer lasers before human photorefractive and therapeutic surgery.

Direct control of transitions between different mode-locking states of a fiber laser

NASA Astrophysics Data System (ADS)

Ilday, Fatih; Teamir, Tesfay; Iegorov, Roman; Makey, Ghaith

Mode-locking corresponds to a far-from-equilibrium steady state of a laser, whereby extremely short pulses can be produced. Capability to directly control mode-locking states can be used to improve laser performance with numerous applications, as well as shed light on their far-from-equilibrium physics using the laser as an experimental platform. Here, we demonstrate direct control of the mode-locking state using spectral pulse shaping by incorporating a spatial light modulator at a Fourier plane inside the cavity of an Yb-doped fiber laser. We show that we can halt and restart mode-locking, suppress instabilities, induce controlled reversible and irreversible transitions between mode-locking states, and perform advanced pulse shaping on pulses as short as 40 fs. This capability can be used to experimentally investigate bifurcations, reversible and irreversible transitions, by selecting, steering, and even competing various mode-locking states. Such studies can explore collective dynamics of dissipative soliton molecules, and ultimately test emerging theories about far-from-equilibrium physics, where there is an acute lack of experimental systems that are sufficiently well controlled. ERC CoG 617521, TUBITAK 113F319.

Lidar Systems for Precision Navigation and Safe Landing on Planetary Bodies

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin; Pierrottet, Diego F.; Petway, Larry B.; Hines, Glenn D.; Roback, Vincent E.

2011-01-01

The ability of lidar technology to provide three-dimensional elevation maps of the terrain, high precision distance to the ground, and approach velocity can enable safe landing of robotic and manned vehicles with a high degree of precision. Currently, NASA is developing novel lidar sensors aimed at needs of future planetary landing missions. These lidar sensors are a 3-Dimensional Imaging Flash Lidar, a Doppler Lidar, and a Laser Altimeter. The Flash Lidar is capable of generating elevation maps of the terrain that indicate hazardous features such as rocks, craters, and steep slopes. The elevation maps collected during the approach phase of a landing vehicle, at about 1 km above the ground, can be used to determine the most suitable safe landing site. The Doppler Lidar provides highly accurate ground relative velocity and distance data allowing for precision navigation to the landing site. Our Doppler lidar utilizes three laser beams pointed to different directions to measure line of sight velocities and ranges to the ground from altitudes of over 2 km. Throughout the landing trajectory starting at altitudes of about 20 km, the Laser Altimeter can provide very accurate ground relative altitude measurements that are used to improve the vehicle position knowledge obtained from the vehicle navigation system. At altitudes from approximately 15 km to 10 km, either the Laser Altimeter or the Flash Lidar can be used to generate contour maps of the terrain, identifying known surface features such as craters, to perform Terrain relative Navigation thus further reducing the vehicle s relative position error. This paper describes the operational capabilities of each lidar sensor and provides a status of their development. Keywords: Laser Remote Sensing, Laser Radar, Doppler Lidar, Flash Lidar, 3-D Imaging, Laser Altimeter, Precession Landing, Hazard Detection

Non-Contact Optical Ultrasound Concept for Biomedical Imaging

DTIC Science & Technology

2016-11-03

Non -Contact Optical Ultrasound Concept for Biomedical Imaging Robert Haupt1, Charles Wynn1, Jonathan Fincke2, Shawn Zhang2, Brian Anthony2...results. Lastly, we present imaging capabilities using a non -contact laser ultrasound proof-of-concept system. Two and three dimensional time... non -contact, standoff optical ultrasound has the potential to provide a fixed reference measurement capability that minimizes operator variability as

PULSAR: A High-Repetition-Rate, High-Power, CE Phase-Locked Laser for the J.R. Macdonald Laboratory at Kansas State University

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ben-Itzhak, Itzik; Carnes, Kevin D.; Cocke, C. Lew

2014-05-09

This instrumentation grant funded the development and installation of a state-of-the-art laser system to be used for the DOE funded research at the J.R. Macdonald Laboratory at Kansas State University. Specifically, we purchased a laser based on the KMLABs Red-Dragon design, which has a high repetition rate of 10-20 kHz crucial for multi-parameter coincidence measurements conducted in our lab. This laser system is carrier-envelope phase (CEP) locked and provides pulses as short as 21 fs directly from the amplifier (see details below). In addition, we have developed a pulse compression setup that provides sub 5 fs pulses and a CEPmore » tagging capability that allows for long measurements of CEP dependent processes.« less

Energy Pooling, Ion Recombination, and Reactions of Rubidium and Cesium in Hydrocarbon Gasses.

NASA Astrophysics Data System (ADS)

Bresler, Sean Michael; Park, J.; Heaven, Michael

2017-06-01

Diode Pumped Alkali Lasers (DPAL) are continuous wave lasers, potentially capable of megawatt average powers. These lasers exploit the D1 and D2 lines of alkali metals resulting in a 3-level laser with the lasing transition in the near infrared region of the electromagnetic spectrum. Energy pooling processes involving collisions between excited alkali metals cause a fraction of the gain media to be highly excited and eventually ionized. These high energy cesium atoms and ions chemically react with small hydrocarbons utilized as buffer gasses for the system, depleting the gain media. A kinetic model supported by experimental data is introduced to explain the cumulative effects of optical trapping, energy pooling, and chemical reactivity in heavy alkali metal (Rb, Cs) systems. Spectroscopic studies demonstrating metal hydride formation will also be presented.

Laser-based nanoengineering of surface topographies for biomedical applications

NASA Astrophysics Data System (ADS)

Schlie, Sabrina; Fadeeva, Elena; Koroleva, Anastasia; Ovsianikov, Aleksandr; Koch, Jürgen; Ngezahayo, Anaclet; Chichkov, Boris. N.

2011-04-01

In this study femtosecond laser systems were used for nanoengineering of special surface topographies in silicon and titanium. Besides the control of feature sizes, we demonstrated that laser structuring caused changes in material wettability due to a reduced surface contact area. These laser-engineered topographies were tested for their capability to control cellular behavior of human fibroblasts, SH-SY5Y neuroblastoma cells, and MG-63 osteoblasts. We found that fibroblasts reduced cell growth on the structures, while the other cell types proliferated at the same rate. These findings make laser-surface structuring very attractive for biomedical applications. Finally, to explain the results the correlation between topography and the biophysics of cellular adhesion, which is the key step of selective cell control, is discussed.

Detection of interference phase by digital computation of quadrature signals in homodyne laser interferometry.

PubMed

Rerucha, Simon; Buchta, Zdenek; Sarbort, Martin; Lazar, Josef; Cip, Ondrej

2012-10-19

We have proposed an approach to the interference phase extraction in the homodyne laser interferometry. The method employs a series of computational steps to reconstruct the signals for quadrature detection from an interference signal from a non-polarising interferometer sampled by a simple photodetector. The complexity trade-off is the use of laser beam with frequency modulation capability. It is analytically derived and its validity and performance is experimentally verified. The method has proven to be a feasible alternative for the traditional homodyne detection since it performs with comparable accuracy, especially where the optical setup complexity is principal issue and the modulation of laser beam is not a heavy burden (e.g., in multi-axis sensor or laser diode based systems).

Intelligent surgical laser system configuration and software implementation

NASA Astrophysics Data System (ADS)

Hsueh, Chi-Fu T.; Bille, Josef F.

1992-06-01

An intelligent surgical laser system, which can help the ophthalmologist to achieve higher precision and control during their procedures, has been developed by ISL as model CLS 4001. In addition to the laser and laser delivery system, the system is also equipped with a vision system (IPU), robotics motion control (MCU), and a tracking closed loop system (ETS) that tracks the eye in three dimensions (X, Y and Z). The initial patient setup is computer controlled with guidance from the vision system. The tracking system is automatically engaged when the target is in position. A multi-level tracking system is developed by integrating our vision and tracking systems which have been able to maintain our laser beam precisely on target. The capabilities of the automatic eye setup and the tracking in three dimensions provides for improved accuracy and measurement repeatability. The system is operated through the Surgical Control Unit (SCU). The SCU communicates with the IPU and the MCU through both ethernet and RS232. Various scanning pattern (i.e., line, curve, circle, spiral, etc.) can be selected with given parameters. When a warning is activated, a voice message is played that will normally require a panel touch acknowledgement. The reliability of the system is ensured in three levels: (1) hardware, (2) software real time monitoring, and (3) user. The system is currently under clinical validation.

Smart CMOS sensor for wideband laser threat detection

NASA Astrophysics Data System (ADS)

Schwarze, Craig R.; Sonkusale, Sameer

2015-09-01

The proliferation of lasers has led to their widespread use in applications ranging from short range standoff chemical detection to long range Lidar sensing and target designation operating across the UV to LWIR spectrum. Recent advances in high energy lasers have renewed the development of laser weapons systems. The ability to measure and assess laser source information is important to both identify a potential threat as well as determine safety and nominal hazard zone (NHZ). Laser detection sensors are required that provide high dynamic range, wide spectral coverage, pulsed and continuous wave detection, and large field of view. OPTRA, Inc. and Tufts have developed a custom ROIC smart pixel imaging sensor architecture and wavelength encoding optics for measurement of source wavelength, pulse length, pulse repetition frequency (PRF), irradiance, and angle of arrival. The smart architecture provides dual linear and logarithmic operating modes to provide 8+ orders of signal dynamic range and nanosecond pulse measurement capability that can be hybridized with the appropriate detector array to provide UV through LWIR laser sensing. Recent advances in sputtering techniques provide the capability for post-processing CMOS dies from the foundry and patterning PbS and PbSe photoconductors directly on the chip to create a single monolithic sensor array architecture for measuring sources operating from 0.26 - 5.0 microns, 1 mW/cm2 - 2 kW/cm2.

Automated cart with VIS/NIR hyperspectral reflectance and fluorescence imaging capabilities

USDA-ARS?s Scientific Manuscript database

A system to take high-resolution VIS/NIR hyperspectral reflectance and fluorescence images in outdoor fields using ambient lighting or a pulsed laser (355 nm), respectively, for illumination was designed, built, and tested. Components of the system include a semi-autonomous cart, a gated-intensified...

Engineering study for pallet adapting the Apollo laser altimeter and photographic camera system for the Lidar Test Experiment on orbital flight tests 2 and 4

NASA Technical Reports Server (NTRS)

Kuebert, E. J.

1977-01-01

A Laser Altimeter and Mapping Camera System was included in the Apollo Lunar Orbital Experiment Missions. The backup system, never used in the Apollo Program, is available for use in the Lidar Test Experiments on the STS Orbital Flight Tests 2 and 4. Studies were performed to assess the problem associated with installation and operation of the Mapping Camera System in the STS. They were conducted on the photographic capabilities of the Mapping Camera System, its mechanical and electrical interface with the STS, documentation, operation and survivability in the expected environments, ground support equipment, test and field support.

Compact 2100 nm laser diode module for next-generation DIRCM

NASA Astrophysics Data System (ADS)

Dvinelis, Edgaras; Greibus, Mindaugas; TrinkÅ«nas, Augustinas; NaujokaitÄ--, Greta; Vizbaras, Augustinas; Vizbaras, Dominykas; Vizbaras, Kristijonas

2017-10-01

Compact high-power 2100 nm laser diode module for next-generation directional infrared countermeasure (DIRCM) systems is presented. Next-generation DIRCM systems require compact, light-weight and robust laser modules which could provide intense IR light emission capable of disrupting the tracking sensor of heat-seeking missile. Currently used solid-state and fiber laser solutions for mid-IR band are bulky and heavy making them difficult to implement in smaller form-factor DIRCM systems. Recent development of GaSb laser diode technology greatly improved optical output powers and efficiencies of laser diodes working in 1900 - 2450 nm band [1] while also maintaining very attractive size, weight, power consumption and cost characteristics. 2100 nm laser diode module presented in this work performance is based on high-efficiency broad emitting area GaSb laser diode technology. Each laser diode emitter is able to provide 1 W of CW output optical power with working point efficiency up to 20% at temperature of 20 °C. For output beam collimation custom designed fast-axis collimator and slow-axis collimator lenses were used. These lenses were actively aligned and attached using UV epoxy curing. Total 2 emitters stacked vertically were used in 2100 nm laser diode module. Final optical output power of the module goes up to 2 W at temperature of 20 °C. Total dimensions of the laser diode module are 35 x 25 x 16 mm (L x W x H) with a weight of 28 grams. Finally output beam is bore-sighted to mechanical axes of the module housing allowing for easy integration into next-generation DIRCM systems.

A cryo-cooled high-energy DPSSL system delivering ns-pulses at 10 J and 10 Hz

NASA Astrophysics Data System (ADS)

Ertel, Klaus; Banerjee, Saumyabrata; Butcher, Thomas J.; De Vido, Mariastefania; Mason, Paul D.; Phillips, P. J.; Richards, David; Shaikh, Waseem; Smith, Jodie M.; Greenhalgh, R. Justin S.; Hernandez-Gomez, Cristina; Collier, John L.

2015-02-01

Lasers generating multi-J to kJ ns-pulses are required for many types of laser-plasma interactions. Such lasers are either used directly for compressing matter to extreme densities or they serve as pump lasers for short-pulses laser chains based on large-aperture Ti:sapphire or parametric amplifiers. The thus generated high-energy fs-pulses are most useful for laser driven secondary sources of particles (electrons, protons) or photons (from THz to gamma). While proof-of-principle experiments have been carried out with flashlamp-pumped glass lasers, lasers with much higher efficiency and repetition rate are required to make this applications practically viable. We have developed a scalable new laser concept called DiPOLE (diode pumped optical laser for experiments) based on a gas-cooled ceramic Yb:YAG multi-slab architecture operating at cryogenic temperatures. While the viability of this concept has been shown earlier [1], we have now reached our target performance of 10 J pulse energy at 10 Hz repetition rate at an optical-to-optical efficiency of 21%. To the best of our knowledge, these are record values for average power and efficiency for lasers of this type. We have also upgraded the system by adding a fibre-based front-end system with arbitrary pulse shaping capability and by installing an image-relayed multipass system enabling up to eight passes of the main amplifier. We have then used this system to demonstrate frequency doubling with 65 % conversion efficiency and a long-term shot-to-shot stability of 0.5% rms over a total of nearly 2 million shots, achieved in runs extending over 4 to 6 hours.

Pseudo-Random Modulation of a Laser Diode for Generating Ultrasonic Longitudinal Waves

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Anatasi, Robert F.

2004-01-01

Laser generated ultrasound systems have historically been more complicated and expensive than conventional piezoelectric based systems, and this fact has relegated the acceptance of laser based systems to niche applications for which piezoelectric based systems are less suitable. Lowering system costs, while improving throughput, increasing ultrasound signal levels, and improving signal-to-noise are goals which will help increase the general acceptance of laser based ultrasound. One current limitation with conventional laser generated ultrasound is a material s damage threshold limit. Increasing the optical power to generate more signal eventually damages the material being tested due to rapid, high heating. Generation limitations for laser based ultrasound suggests the use of pulse modulation techniques as an alternate generation method. Pulse modulation techniques can spread the laser energy over time or space, thus reducing laser power densities and minimizing damage. Previous experiments by various organizations using spatial or temporal pulse modulation have been shown to generate detectable surface, plate, and bulk ultrasonic waves with narrow frequency bandwidths . Using narrow frequency bandwidths improved signal detectability, but required the use of expensive and powerful lasers and opto-electronic systems. The use of a laser diode to generate ultrasound is attractive because of its low cost, small size, light weight, simple optics and modulation capability. The use of pulse compression techniques should allow certain types of laser diodes to produce usable ultrasonic signals. The method also does not need to be limited to narrow frequency bandwidths. The method demonstrated here uses a low power laser diode (approximately 150 mW) that is modulated by controlling the diode s drive current and the resulting signal is recovered by cross correlation. A potential application for this system which is briefly demonstrated is in detecting signals in thick composite materials where attenuation is high and signal amplitude and bandwidth are at a premium.

Laser dimpling process parameters selection and optimization using surrogate-driven process capability space

NASA Astrophysics Data System (ADS)

Ozkat, Erkan Caner; Franciosa, Pasquale; Ceglarek, Dariusz

2017-08-01

Remote laser welding technology offers opportunities for high production throughput at a competitive cost. However, the remote laser welding process of zinc-coated sheet metal parts in lap joint configuration poses a challenge due to the difference between the melting temperature of the steel (∼1500 °C) and the vapourizing temperature of the zinc (∼907 °C). In fact, the zinc layer at the faying surface is vapourized and the vapour might be trapped within the melting pool leading to weld defects. Various solutions have been proposed to overcome this problem over the years. Among them, laser dimpling has been adopted by manufacturers because of its flexibility and effectiveness along with its cost advantages. In essence, the dimple works as a spacer between the two sheets in lap joint and allows the zinc vapour escape during welding process, thereby preventing weld defects. However, there is a lack of comprehensive characterization of dimpling process for effective implementation in real manufacturing system taking into consideration inherent changes in variability of process parameters. This paper introduces a methodology to develop (i) surrogate model for dimpling process characterization considering multiple-inputs (i.e. key control characteristics) and multiple-outputs (i.e. key performance indicators) system by conducting physical experimentation and using multivariate adaptive regression splines; (ii) process capability space (Cp-Space) based on the developed surrogate model that allows the estimation of a desired process fallout rate in the case of violation of process requirements in the presence of stochastic variation; and, (iii) selection and optimization of the process parameters based on the process capability space. The proposed methodology provides a unique capability to: (i) simulate the effect of process variation as generated by manufacturing process; (ii) model quality requirements with multiple and coupled quality requirements; and (iii) optimize process parameters under competing quality requirements such as maximizing the dimple height while minimizing the dimple lower surface area.

Toward a New Capability for Upper Atmospheric Research using Atomic Oxygen Lidar

NASA Astrophysics Data System (ADS)

Clemmons, J. H.; Steinvurzel, P.; Mu, X.; Beck, S. M.; Lotshaw, W. T.; Rose, T. S.; Hecht, J. H.; Westberg, K. R.; Larsen, M. F.; Chu, X.; Fritts, D. C.

2017-12-01

Progress on development of a lidar system for probing the upper atmosphere based on atomic oxygen resonance is presented and discussed. The promise of a fully-developed atomic oxygen lidar system, which must be based in space to measure the upper atmosphere, for yielding comprehensive new insights is discussed in terms of its potential to deliver global, height-resolved measurements of winds, temperature, and density at a high cadence. An overview of the system is given, and its measurement principles are described, including its use of 1) a two-photon transition to keep the optical depth low; 2) laser tuning to provide the Doppler information needed to measure winds; and 3) laser tuning to provide a Boltzmann temperature measurement. The current development status is presented with a focus on what has been done to demonstrate capability in the laboratory and its evolution to a funded sounding rocket investigation designed to make measurements of three-dimensional turbulence in the upper mesosphere and lower thermosphere.

Intelligent robotic tracker

NASA Technical Reports Server (NTRS)

Otaguro, W. S.; Kesler, L. O.; Land, K. C.; Rhoades, D. E.

1987-01-01

An intelligent tracker capable of robotic applications requiring guidance and control of platforms, robotic arms, and end effectors has been developed. This packaged system capable of supervised autonomous robotic functions is partitioned into a multiple processor/parallel processing configuration. The system currently interfaces to cameras but has the capability to also use three-dimensional inputs from scanning laser rangers. The inputs are fed into an image processing and tracking section where the camera inputs are conditioned for the multiple tracker algorithms. An executive section monitors the image processing and tracker outputs and performs all the control and decision processes. The present architecture of the system is presented with discussion of its evolutionary growth for space applications. An autonomous rendezvous demonstration of this system was performed last year. More realistic demonstrations in planning are discussed.

Contamination and UV lasers: lessons learned

NASA Astrophysics Data System (ADS)

Daly, John G.

2015-09-01

Laser induced damage to optical elements has been a subject of significant research, development, and improvement, since the first lasers were built over the last 50 years. Better materials, with less absorption, impurities, and defects are available, as well as surface coatings with higher laser damage resistance. However, the presence of contamination (particles, surface deposition films, or airborne) can reduce the threshold for damage by several orders of magnitude. A brief review of the anticipated laser energy levels for damage free operation is presented as a lead into the problems associated with contamination for ultraviolet (UV) laser systems. As UV lasers become more common in applications especially in areas such as lithography, these problems have limited reliability and added to costs. This has been characterized as Airborne Molecular Contamination (AMC) in many published reports. Normal engineering guidelines such as screening materials within the optical compartment for low outgassing levels is the first step. The use of the NASA outgassing database (or similar test methods) with low Total Mass Loss (TML) and Condensed Collected Volatiles Collected Mass (CVCM) is a good baseline. Energetic UV photons are capable of chemical bond scission and interaction with surface contaminant or airborne materials results in deposition of obscuring film laser footprints that continue to degrade laser system performance. Laser systems with average powers less than 5 mW have been shown to exhibit aggressive degradation. Lessons learned over the past 15 years with UV laser contamination and steps to reduce risk will be presented.

Consolidated Laser-Induced Fluorescence Diagnostic Systems for the NASA Ames Arc Jet Facilities

NASA Technical Reports Server (NTRS)

Grinstead, Jay H.; Wilder, Michael C.; Porter, Barry J.; Brown, Jeffrey D.; Yeung, Dickson; Battazzo, Stephen J.; Brubaker, Timothy R.

2016-01-01

The spectroscopic diagnostic technique of two photon absorption laser-induced fluorescence (TALIF) of atomic species for non-intrusive arc jet flow property measurement was first implemented at NASA Ames in the mid-1990s. Use of TALIF expanded at NASA Ames and to NASA Johnson's arc jet facility in the late 2000s. In 2013-2014, NASA combined the agency's large-scale arc jet test capabilities at NASA Ames. Concurrent with that effort, the agency also sponsored a project to establish two comprehensive LIF diagnostic systems for the Aerodynamic Heating Facility (AHF) and Interaction Heating Facility (IHF) arc jets. The scope of the project enabled further engineering development of the existing IHF LIF system as well as the complete reconstruction of the original AHF LIF system. The updated LIF systems are identical in design and capability. They represent the culmination of over 20 years of development experience in transitioning a specialized laboratory research tool into a measurement system for large-scale, high-demand test facilities. This paper documents the overall system design from measurement requirements to implementation. Representative data from the redeveloped AHF and IHF LIF systems are also presented.

Consolidated Laser-Induced Fluorescence Diagnostic Systems for the NASA Ames Arc Jet Facilities

NASA Technical Reports Server (NTRS)

Grinstead, Jay; Wilder, Michael C.; Porter, Barry; Brown, Jeff; Yeung, Dickson; Battazzo, Steve; Brubaker, Tim

2016-01-01

The spectroscopic diagnostic technique of two photon absorption laser-induced fluorescence (TALIF) of atomic species for non-intrusive arc jet flow property measurement was first implemented at NASA Ames in the mid-1990s. Use of TALIF expanded at NASA Ames and to NASA Johnsons arc jet facility in the late 2000s. In 2013-2014, NASA combined the agency's large-scale arc jet test capabilities at NASA Ames. Concurrent with that effort, the agency also sponsored a project to establish two comprehensive LIF diagnostic systems for the Aerodynamic Heating Facility (AHF) and Interaction Heating Facility (IHF) arc jets. The scope of the project enabled further engineering development of the existing IHF LIF system as well as the complete reconstruction of the original AHF LIF system. The updated LIF systems are identical in design and capability. They represent the culmination of over 20 years of development experience in transitioning a specialized laboratory research tool into a measurement system for large-scale, high-demand test facilities. This paper documents the overall system design from measurement requirements to implementation. Representative data from the redeveloped AHF and IHF LIF systems are also presented.

Improvements to Optical Communication Capabilities Achieved through the Optical Injection of Semiconductor Lasers

DTIC Science & Technology

2012-03-22

locked Fabry - Perot laser showed a 57 fold improvement to the bit rate-distance product compared to the free-running case when received optical power...than 10dB for marginal changes in modulation rates. Temperature tuning of the master laser to each of the Fabry - Perot modes of the slave laser...demonstrated over 60 km of SMF in this work, shows that OIL of Fabry - Perot lasers is a viable approach towards a high-speed, long distance capable

NASA-sponsored containerless processing experiments

NASA Technical Reports Server (NTRS)

Hofmeister, William H.

1990-01-01

An outline is presented of containerless processing and facilities at Intersonics which is sponsored by NASA. There are electromagnetic, acoustic, and aerodynamic levitation facilities. There are also laser beam and arc lamp heating systems along with state of the art noncontact temperature and optical property measurement facilities. Nonintrusive diagnostic techniques with Laser Induced Fluorescence and mass spectrometer are also available. Controlled atmosphere processing, gas quenching, and proven microgravity processing technology is part of the Intersonics capabilities.

Miniature fiber-optic multiphoton microscopy system using frequency-doubled femtosecond Er-doped fiber laser

PubMed Central

Huang, Lin; Mills, Arthur K.; Zhao, Yuan; Jones, David J.; Tang, Shuo

2016-01-01

We report on a miniature fiber-optic multiphoton microscopy (MPM) system based on a frequency-doubled femtosecond Er-doped fiber laser. The femtosecond pulses from the laser source are delivered to the miniature fiber-optic probe at 1.58 µm wavelength, where a standard single mode fiber is used for delivery without the need of free-space dispersion compensation components. The beam is frequency-doubled inside the probe by a periodically poled MgO:LiNbO3 crystal. Frequency-doubled pulses at 786 nm with a maximum power of 80 mW and a pulsewidth of 150 fs are obtained and applied to excite intrinsic signals from tissues. A MEMS scanner, a miniature objective, and a multimode collection fiber are further used to make the probe compact. The miniature fiber-optic MPM system is highly portable and robust. Ex vivo multiphoton imaging of mammalian skins demonstrates the capability of the system in imaging biological tissues. The results show that the miniature fiber-optic MPM system using frequency-doubled femtosecond fiber laser can potentially bring the MPM imaging for clinical applications. PMID:27231633

Portable laser speckle perfusion imaging system based on digital signal processor.

PubMed

Tang, Xuejun; Feng, Nengyun; Sun, Xiaoli; Li, Pengcheng; Luo, Qingming

2010-12-01

The ability to monitor blood flow in vivo is of major importance in clinical diagnosis and in basic researches of life science. As a noninvasive full-field technique without the need of scanning, laser speckle contrast imaging (LSCI) is widely used to study blood flow with high spatial and temporal resolution. Current LSCI systems are based on personal computers for image processing with large size, which potentially limit the widespread clinical utility. The need for portable laser speckle contrast imaging system that does not compromise processing efficiency is crucial in clinical diagnosis. However, the processing of laser speckle contrast images is time-consuming due to the heavy calculation for enormous high-resolution image data. To address this problem, a portable laser speckle perfusion imaging system based on digital signal processor (DSP) and the algorithm which is suitable for DSP is described. With highly integrated DSP and the algorithm, we have markedly reduced the size and weight of the system as well as its energy consumption while preserving the high processing speed. In vivo experiments demonstrate that our portable laser speckle perfusion imaging system can obtain blood flow images at 25 frames per second with the resolution of 640 × 480 pixels. The portable and lightweight features make it capable of being adapted to a wide variety of application areas such as research laboratory, operating room, ambulance, and even disaster site.

Measurements with magnetic field in the National Spherical Torus Experiment using the motional Stark effect with laser induced fluorescence diagnostic

NASA Astrophysics Data System (ADS)

Foley, E. L.; Levinton, F. M.

2013-04-01

The motional Stark effect with laser-induced fluorescence diagnostic (MSE-LIF) has been installed and tested on the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Lab. The MSE-LIF diagnostic will be capable of measuring radially resolved profiles of magnetic field magnitude or pitch angle in NSTX plasmas. The system includes a diagnostic neutral hydrogen beam and a laser which excites the n = 2 to n = 3 transition. A viewing system has been implemented which will support up to 38 channels from the plasma edge to past the magnetic axis. First measurements of MSE-LIF signals in the presence of small applied magnetic fields in neutral gas are reported.

Modeling, development, and testing of a shortwave infrared supercontinuum laser source for use in active hyperspectral imaging

NASA Astrophysics Data System (ADS)

Meola, Joseph; Absi, Anthony; Leonard, James D.; Ifarraguerri, Agustin I.; Islam, Mohammed N.; Alexander, Vinay V.; Zadnik, Jerome A.

2013-05-01

A fundamental limitation of current visible through shortwave infrared hyperspectral imaging systems is the dependence on solar illumination. This reliance limits the operability of such systems to small windows during which the sun provides enough solar radiation to achieve adequate signal levels. Similarly, nighttime collection is infeasible. This work discusses the development and testing of a high-powered super-continuum laser for potential use as an on-board illumination source coupled with a hyperspectral receiver to allow for day/night operability. A 5-watt shortwave infrared supercontinuum laser was developed, characterized in the lab, and tower-tested along a 1.6km slant path to demonstrate propagation capability as a spectral light source.

Near infra-red astronomy with adaptive optics and laser guide stars at the Keck Observatory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Max, C.E.; Gavel, D.T.; Olivier, S.S.

1995-08-03

A laser guide star adaptive optics system is being built for the W. M. Keck Observatory`s 10-meter Keck II telescope. Two new near infra-red instruments will be used with this system: a high-resolution camera (NIRC 2) and an echelle spectrometer (NIRSPEC). The authors describe the expected capabilities of these instruments for high-resolution astronomy, using adaptive optics with either a natural star or a sodium-layer laser guide star as a reference. They compare the expected performance of these planned Keck adaptive optics instruments with that predicted for the NICMOS near infra-red camera, which is scheduled to be installed on the Hubblemore » Space Telescope in 1997.« less

ArI/ArII laser induced fluorescence system for measurement of neutral and ion dynamics in a large scale helicon plasma

NASA Astrophysics Data System (ADS)

Kelly, R. F.; Meaney, K. D.; Gilmore, M.; Desjardins, T. R.; Zhang, Y.

2016-11-01

In order to investigate the role of both neutral and ion dynamics in large-scale helicon discharges, a laser induced fluorescence (LIF) system capable of measuring both ArI and ArII fluorescence using a single tunable laser is being developed. The system is based on a >250 mW solid state laser. For ArI measurements, the laser pumps the metastable (2P03/2)4s level to the (2P01/2)4p level using 696.7352 nm light, and fluorescence radiation from decay to the (2P01/2)4s level at 772.6333 nm is observed. For ArII, currently in development, the metastable (3P)3d 4F7/2 level will be pumped to the (3P)4p 4D07/2 level using 688.8511 nm, and decay fluorescence to the (3P)4s 4P5/2 level at 434.9285 nm measured. Here all wavelengths are in a vacuum.

ArI/ArII laser induced fluorescence system for measurement of neutral and ion dynamics in a large scale helicon plasma.

PubMed

Kelly, R F; Meaney, K D; Gilmore, M; Desjardins, T R; Zhang, Y

2016-11-01

In order to investigate the role of both neutral and ion dynamics in large-scale helicon discharges, a laser induced fluorescence (LIF) system capable of measuring both ArI and ArII fluorescence using a single tunable laser is being developed. The system is based on a >250 mW solid state laser. For ArI measurements, the laser pumps the metastable ( 2 P 0 3/2 )4s level to the ( 2 P 0 1/2 )4p level using 696.7352 nm light, and fluorescence radiation from decay to the ( 2 P 0 1/2 )4s level at 772.6333 nm is observed. For ArII, currently in development, the metastable ( 3 P)3d 4 F 7/2 level will be pumped to the ( 3 P)4p 4 D 0 7/2 level using 688.8511 nm, and decay fluorescence to the ( 3 P)4s 4 P 5/2 level at 434.9285 nm measured. Here all wavelengths are in a vacuum.

Space Applications of Industrial Laser Systems (SAILS)

NASA Technical Reports Server (NTRS)

Mueller, Robert E.; McCay, T. Dwayne; McCay, Mary Helen; Bible, Brice

1992-01-01

A program is under way to develop a YAG laser based materials processing workstation to fly in the cargo bay of the Space Shuttle. The system will be capable of cutting and welding steel, aluminum and Inconel alloys of the type planned for use on the Space Station Freedom. As well as demonstrating the ability of a YAG laser to perform remote (fiber-optic delivered) repair and fabrication operations in space, fundamental data will be collected on these interactions for comparison with terrestrial data and models. The flight system, scheduled to fly in 1995, will be constructed as two modules to fit into standard Get Away Special (GAS) canisters. The first can holds the laser and its power supply, to be constructed by our industrial partner, Lumonics Industrial Processing Division. The second canister has the materials processing workstation and the command and data acquisition subsystems. These components will be provided by groups at UTSI and the University of Waterloo. The cans are linked by a fiber-optic cable which transmits the beam from the laser head to the workstation.

Space Applications of Industrial Laser Systems (SAILS)

NASA Technical Reports Server (NTRS)

Mueller, Robert E.; McCay, T. Dwayne; McCay, Mary Helen; Bible, Brice

1995-01-01

A program is under way to develop a YAG laser based materials processing workstation to fly in the cargo bay of the Space Shuttle. The system will be capable of cutting and welding steel, aluminum, and Inconel alloys of the type planned for use on Space Station Freedom. As well as demonstrating the ability of a YAG laser to perform remote (fiber-optic delivered) repair and fabrication operations in space, fundamental data will be collected on these interactions for comparison with terrestrial data and models. The flight system, scheduled to fly in 1995, will be constructed as two modules to fit into the standard Get Away Special (GAS) canisters. The first can holds the laser and its power supply, to be constructed by our industrial partner, Lumonics Industrial Processing Division. The second canister has the materials processing workstation and the command and data acquisition subsystems. These components will be provided by groups at the University of Tennessee Space Institute (UTSI) and the University of Waterloo. The cans are linked by a fiber-optic cable which transmits the beam from the laser head to the workstation.

Laser electro-optic system for rapid three-dimensional /3-D/ topographic mapping of surfaces

NASA Technical Reports Server (NTRS)

Altschuler, M. D.; Altschuler, B. R.; Taboada, J.

1981-01-01

It is pointed out that the generic utility of a robot in a factory/assembly environment could be substantially enhanced by providing a vision capability to the robot. A standard videocamera for robot vision provides a two-dimensional image which contains insufficient information for a detailed three-dimensional reconstruction of an object. Approaches which supply the additional information needed for the three-dimensional mapping of objects with complex surface shapes are briefly considered and a description is presented of a laser-based system which can provide three-dimensional vision to a robot. The system consists of a laser beam array generator, an optical image recorder, and software for controlling the required operations. The projection of a laser beam array onto a surface produces a dot pattern image which is viewed from one or more suitable perspectives. Attention is given to the mathematical method employed, the space coding technique, the approaches used for obtaining the transformation parameters, the optics for laser beam array generation, the hardware for beam array coding, and aspects of image acquisition.

Laser Doppler systems in pollution monitoring

NASA Technical Reports Server (NTRS)

Miller, C. R.; Sonnenschein, C. M.; Herget, W. F.; Huffaker, R. M.

1976-01-01

The paper reports on a program undertaken to determine the feasibility of using a laser Doppler velocimeter (LDV) to measure smoke-stack gas exit velocity, particulate concentration, and mass flow. Measurements made with a CO2 laser Doppler radar system at a coal-burning power plant are compared with in-stack measurements made by a pitot tube. The operational principles of a LDV are briefly described along with the system employed in the present study. Data discussed include typical Doppler spectra from smoke-stack effluents at various laser elevation angles, the measured velocity profile across the stack exit, and the LDV-measured exit velocity as a function of the exit velocity measured by the in-stack instrument. The in-stack velocity is found to be about 14% higher than the LDV velocity, but this discrepancy is regarded as a systematic error. In general, linear relationships are observed between the laser data, the exit velocity, and the particulate concentration. It is concluded that an LDV has the capability of determining both the mass concentration and the mass flow from a power-plant smoke stack.

Next-generation laser for inertial confinement fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marshall, C; Bibeau, C; Bayramian, A

1998-03-13

We are developing and building the ''Mercury'' laser system as the first in a series of a new generation of diode-pumped solid-state lasers (DPSSL) for advanced high energy density (HED) physics experiments at LLNL. Mercury will be the first integrated demonstration of a scalable laser architecture compatible with advanced Inertial Confinement Fusion (ICF) goals. Primary performance goals include 10% efficiencies at 10 Hz and a <10 ns pulse with l {omega} energies of 100 J and with 2 {omega}/3 {omega} frequency conversion. Achieving this performance will provide a near term capability for HED experiments and prove the potential of DPSSLsmore » for inertial fusion energy (IFE).« less

Thomson Parabola Spectrometer: a powerful tool for on-line plasma analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Altana, C.; Muoio, A.; Schillaci, F.

2015-07-01

In this paper we report on a new powerful and self-consistent analysis technique aimed in order to get information online on laser generated plasmas. Performance of the method has been carried out during two set of measurement by using two different lasers. The first set of data has been collected at LENS Laboratory of INFN-LNS in Catania by using a laser which produces pulses having energies of 2 J and temporal duration of 6 ns, while the second set of data has been collected at ILIL of INO-CNR in Pisa with a laser system capable of delivering pulses of upmore » to 10 mJ in 40 fs. (authors)« less

A new mass spectrometer system for investigating laser-induced vaporization phenomena

NASA Technical Reports Server (NTRS)

Lincoln, K. A.

1974-01-01

A laser has been combined with a mass spectrometer in a new configuration developed for studies of high-temperature materials. A vacuum-lock, solid-sample inlet is mounted at one end of a cylindrical, high-vacuum chamber one meter in length with a nude ion-source, time-of-flight mass spectrometer at the opposite end. The samples are positioned along the axis of the chamber at distances up to one meter from the ion source, and their surfaces are vaporized by a pulsed laser beam entering via windows on one side of the chamber. The instrumentation along with its capabilities is described, and results from laser-induced vaporization of several graphites are presented.

Laser Ranging in Solar System: Technology Developments and New Science Measurement Capabilities

NASA Astrophysics Data System (ADS)

Sun, X.; Smith, D. E.; Zuber, M. T.; Mcgarry, J.; Neumann, G. A.; Mazarico, E.

2015-12-01

Laser Ranging has played a major role in geodetic studies of the Earth over the past 40 years. The technique can potentially be used in between planets and spacecrafts within the solar system to advance planetary science. For example, a direct measurement of distances between planets, such as Mars and Venus would make significant improvements in understanding the dynamics of the whole solar system, including the masses of the planets and moons, asteroids and their perturbing interactions, and the gravity field of the Sun. Compared to the conventional radio frequency (RF) tracking systems, laser ranging is potentially more accurate because it is much less sensitive to the transmission media. It is also more efficient because the laser beams are much better focused onto the targets than RF beams. However, existing laser ranging systems are all Earth centric, that is, from ground stations on Earth to orbiting satellites in near Earth orbits or lunar orbit, and to the lunar retro-reflector arrays deployed by the astronauts in the early days of lunar explorations. Several long distance laser ranging experiments have been conducted with the lidar in space, including a two-way laser ranging demonstration between Earth and the Mercury Laser Altimeter (MLA) on the MESSENGER spacecraft over 24 million km, and a one way laser transmission and detection experiment over 80 million km between Earth and the Mars Orbiting Laser Altimeter (MOLA) on the MGS spacecraft in Mars orbit. A one-way laser ranging operation has been carried out continuously from 2009 to 2014 between multiple ground stations to LRO spacecraft in lunar orbit. The Lunar Laser Communication Demonstration (LLCD) on the LADEE mission has demonstrated that a two way laser ranging measurements, including both the Doppler frequency and the phase shift, can be obtained from the subcarrier or the data clocks of a high speed duplex laser communication system. Plans and concepts presently being studied suggest we may be on the cusp of demonstrating interplanetary laser ranging to bring the future of solar system geodesy and geodyamics into reality.

Quantification of wind flow in the European Mars Simulation Wind Tunnel Facility

NASA Astrophysics Data System (ADS)

Holstein-Rathlou, C.; Merrison, J. P.; Iversen, J. J.; Nornberg, P.

2012-04-01

We present the European Mars Simulation Wind Tunnel facility, a unique prototype facility capable of simulating a wide range of environmental conditions, such as those which can be found at the surface of Earth or Mars. The chamber complements several other large-scale simulation facilities at Aarhus University, Denmark. The facility consists of a 50 m3 environmental chamber capable of operating at low pressure (0.02 - 1000 mbar) and cryogenic temperatures (-130 °C up to +60 °C). This chamber houses a re-circulating wind tunnel capable of generating wind speeds up to 25 m/s and has a dust injection system that can produce suspended particulates (aerosols). It employs a unique LED based optical illumination system (solar simulator) and an advanced network based control system. Laser based optoelectronic instrumentation is used to quantify and monitor wind flow, dust suspension and deposition. This involves a commercial Laser Doppler Anemometer (LDA) and a Particle Dynamics Analysis receiver (PDA), which are small laser based instruments specifically designed for measuring wind speed and sizes of particles situated in a wind flow. Wind flow calibrations will be performed with the LDA system and presented. Pressure and temperature calibrations will follow in order to enable the facility to be used for the testing, development, calibration and comparison of e.g. meteorological sensors under a wide range of environmental conditions as well as multi-disciplinary scientific studies. The wind tunnel is accessible to international collaborators and space agencies for instrument testing, calibration and qualification. It has been financed by the European Space Agency (ESA) as well as the Aarhus University Science Faculty and the Villum Kann Rasmussen Foundation.

UAV-borne lidar with MEMS mirror-based scanning capability

NASA Astrophysics Data System (ADS)

Kasturi, Abhishek; Milanovic, Veljko; Atwood, Bryan H.; Yang, James

2016-05-01

Firstly, we demonstrated a wirelessly controlled MEMS scan module with imaging and laser tracking capability which can be mounted and flown on a small UAV quadcopter. The MEMS scan module was reduced down to a small volume of <90mm x 60mm x 40mm, weighing less than 40g and consuming less than 750mW of power using a ~5mW laser. This MEMS scan module was controlled by a smartphone via Bluetooth while flying on a drone, and could project vector content, text, and perform laser based tracking. Also, a "point-and-range" LiDAR module was developed for UAV applications based on low SWaP (Size, Weight and Power) gimbal-less MEMS mirror beam-steering technology and off-the-shelf OEM LRF modules. For demonstration purposes of an integrated laser range finder module, we used a simple off-the-shelf OEM laser range finder (LRF) with a 100m range, +/-1.5mm accuracy, and 4Hz ranging capability. The LRFs receiver optics were modified to accept 20° of angle, matching the transmitter's FoR. A relatively large (5.0mm) diameter MEMS mirror with +/-10° optical scanning angle was utilized in the demonstration to maintain the small beam divergence of the module. The complete LiDAR prototype can fit into a small volume of <70mm x 60mm x 60mm, and weigh <50g when powered by the UAV's battery. The MEMS mirror based LiDAR system allows for ondemand ranging of points or areas within the FoR without altering the UAV's position. Increasing the LRF ranging frequency and stabilizing the pointing of the laser beam by utilizing the onboard inertial sensors and the camera are additional goals of the next design.

Blue 450nm high power semiconductor continuous wave laser bars exceeding rollover output power of 80W

NASA Astrophysics Data System (ADS)

König, H.; Lell, A.; Stojetz, B.; Ali, M.; Eichler, C.; Peter, M.; Löffler, A.; Strauss, U.; Baumann, M.; Balck, A.; Malchus, J.; Krause, V.

2018-02-01

Industrial material processing like cutting or welding of metals is rather energy efficient using direct diode or diode pumped solid state lasers. However, many applications cannot be addressed by established infrared laser technology due to fundamental material properties of the workpiece: For example materials like copper or gold have too low absorption in the near infrared wavelength range to be processed efficiently by use of existing high power laser systems. The huge interest to enable high power kW systems with more suitable wavelengths in the blue spectral range triggered the German funded research project 'BLAULAS': Therein the feasibility and capability of CW operating high power laser bars based on the GaN material system was investigated by Osram and Laserline. High performance bars were enabled by defeating fundamental challenges like material quality as well as the chip processes, both of which differ significantly from well-known IR laser bars. The research samples were assembled on actively cooled heat sinks with hard solder technology. For the first time an output power of 98W per bar at 60A drive current was achieved. Conversion efficiency as high as 46% at 50W output power was demonstrated.

Progress in diode-pumped alexandrite lasers as a new resource for future space lidar missions

NASA Astrophysics Data System (ADS)

Damzen, M. J.; Thomas, G. M.; Teppitaksak, A.; Minassian, A.

2017-11-01

Satellite-based remote sensing using laser-based lidar techniques provides a powerful tool for global 3-D mapping of atmospheric species (e.g. CO2, ozone, clouds, aerosols), physical attributes of the atmosphere (e.g. temperature, wind speed), and spectral indicators of Earth features (e.g. vegetation, water). Such information provides a valuable source for weather prediction, understanding of climate change, atmospheric science and health of the Earth eco-system. Similarly, laser-based altimetry can provide high precision ground topography mapping and more complex 3-D mapping (e.g. canopy height profiling). The lidar technique requires use of cutting-edge laser technologies and engineered designs that are capable of enduring the space environment over the mission lifetime. The laser must operate with suitably high electrical-to-optical efficiency and risk reduction strategy adopted to mitigate against laser failure or excessive operational degradation of laser performance.

NASA's Preparations for ESA's L3 Gravitational Wave Mission

NASA Technical Reports Server (NTRS)

Stebbins, Robin

2016-01-01

Telescope Subsystem - Jeff Livas (GSFC): Demonstrate pathlength stability, straylight and manufacturability. Phase Measurement System - Bill Klipstein (JPL): Key measurement functions demonstrated. Incorporate full flight functionality. Laser Subsystem - Jordan Camp (GSFC): ECL master oscillator, phase noise of fiber power amplifier, demonstrate end-to-end performance in integrated system, lifetime. Micronewton Thrusters - John Ziemer (JPL): Propellant storage and distribution, system robustness, manufacturing yield, lifetime. Arm-locking Demonstration - Kirk McKenzie (JPL): Studying a demonstration of laser frequency stabilization with GRACE Follow-On. Torsion Pendulum - John Conklin (UF): Develop U.S. capability with GRS and torsion pendulum test bed. Multi-Axis Heterodyne Interferometry - Ira Thorpe (GSFC): Investigate test mass/optical bench interface. UV LEDs - John Conklin+ (UF): Flight qualify UV LEDs to replace mercury lamps in discharging system. Optical Bench - Guido Mueller (UF): Investigate alternate designs and fabrication processes to ease manufacturability. LISA researchers at JPL are leading the Laser Ranging Interferometer instrument on the GRACE Follow-On mission.

Visual based laser speckle pattern recognition method for structural health monitoring

NASA Astrophysics Data System (ADS)

Park, Kyeongtaek; Torbol, Marco

2017-04-01

This study performed the system identification of a target structure by analyzing the laser speckle pattern taken by a camera. The laser speckle pattern is generated by the diffuse reflection of the laser beam on a rough surface of the target structure. The camera, equipped with a red filter, records the scattered speckle particles of the laser light in real time and the raw speckle image of the pixel data is fed to the graphic processing unit (GPU) in the system. The algorithm for laser speckle contrast analysis (LASCA) computes: the laser speckle contrast images and the laser speckle flow images. The k-mean clustering algorithm is used to classify the pixels in each frame and the clusters' centroids, which function as virtual sensors, track the displacement between different frames in time domain. The fast Fourier transform (FFT) and the frequency domain decomposition (FDD) compute the modal properties of the structure: natural frequencies and damping ratios. This study takes advantage of the large scale computational capability of GPU. The algorithm is written in Compute Unifies Device Architecture (CUDA C) that allows the processing of speckle images in real time.

Ultraprecise medical applications with ultrafast lasers: corneal surgery with femtosecond lasers

NASA Astrophysics Data System (ADS)

Loesel, Frieder H.; Kurtz, Ron M.; Horvath, Christopher; Sayegh, Samir I.; Mourou, Gerard A.; Bille, Josef F.; Juhasz, Tibor

1999-02-01

We investigated refractive corneal surgery in vivo and in vitro by intrastromal photodisruption using a compact ultrafast femtosecond laser system. Ultrashort-pulsed lasers operating in the femtosecond time regime are associated with significantly smaller and deterministic threshold energies for photodisruption, as well as reduced shock waves and smaller cavitation bubbles than the nanosecond or picosecond lasers. Our reliable all-solid-state laser system was specifically designed for real world medical applications. By scanning the 5 micron focus spot of the laser below the corneal surface, the overlapping small ablation volumes of single pulses resulted in contiguous tissue cutting and vaporization. Pulse energies were typically in the order of a few microjoules. Combination of different scanning patterns enabled us to perform corneal flap cutting, femtosecond-LASIK, and femtosecond intrastromal keratectomy in porcine, rabbit, and primate eyes. The cuts proved to be highly precise and possessed superior dissection and surface quality. Preliminary studies show consistent refractive changes in the in vivo studies. We conclude that the technology is capable to perform a variety of corneal refractive procedures at high precision, offering advantages over current mechanical and laser devices and enabling entirely new approaches for refractive surgery.

Development of an advanced uncooled 10-Gb DFB laser for volume manufacture

NASA Astrophysics Data System (ADS)

Burns, Gordon; Charles, Paul M.

2003-03-01

Optical communication systems operating at 10Gbit/s such as 10Gigabit Ethernet are becoming more and more important in Local Area Networks (LAN) and Metropolitan Area Networks (MAN). This market requires optical transceivers of low cost, size and power consumption. This drives a need for uncooled DFB lasers directly modulated at 10Gbit/s. This paper describes the development of a state of the art uncooled high speed DFB laser which is capable of being manufactured in high volume at the low cost demanded by the GbE market. A DFB laser was designed by developing technological building blocks within the 'conventional" InGaAsP materials system, using existing well proven manufacturing processes modules wherever possible, limiting the design risk to a few key areas where innovation was required. The temperature and speed performance of the InGaAsP SMQW active layer system was carefully optimized and then coupled with a low parasitic lateral confinement system. Using concurrent engineering, new processes were demonstrated to have acceptable process capability within a manufacturing fabrication environment, proving their ability to support high volume manufacturing requirements. The DFB laser fabricated was shown to operate at 100C chip temperature with an open eye at 10Gbit/s operation (with an extinction ratio >5dB). Up to 90C operation this DFB shows threshold current as low as 29mA, optical power as high as 13mW and it meets the 10Gb scaled Ethernet mask with extinction ratio >6dB. It was found that the high temperature dynamic behavior of these lasers could not be fully predicted from static test data. A production test strategy was therefore followed where equipment was designed to fully test devices/subassemblies at 100C and up to 20Gbit/s at key points in the product build. This facilitated the rapid optimisation of product yields upon manufacturing ramp up and minimization of product costs. This state of the art laser is now transferred into volume manufacture.

Instrumentation For The Surgical Application Of The Nd:YAG Laser

NASA Astrophysics Data System (ADS)

Frank, F.; Bailer, P.; Beck, O.; Bowering, R.; Hofstetter, A.

1984-03-01

The Nd:YAG laser has become a coagulation instrument, which has found acceptance in interdisciplinary surgery. The main contributors are its highly efficient coagulation capability in interaction with tissue and the fact that the Nd:YAG laser beam can be transmitted by means of a simple quartz-glass fiber. Appropriate systems and instruments for transmission and operation have been developed for the various applications in neurosurgery, pulmology, gastroenterology, urology, gynaecology and dermatology. Operation methods in open and endoscopic surgery under use of several hand held devices and flexible as well as rigid endoscopes are being demonstrated by clinical examples of application.

Antares alignment gimbal positioner

NASA Astrophysics Data System (ADS)

Day, R. D.; Viswanathan, V. K.; Saxman, A. C.; Lujan, R. E.; Woodfin, W. C.; Sweatt, W. C.

Antares is a 24-beam 40-TW carbon dioxide (CO2) laser fusion system currently under construction at the Los Alamos National Laboratory. The Antares alignment gimbal positioner (AGP) is an optomechanical instrument that will be used for target alignment and alignment of the 24 laser beams, as well as beam quality assessments. The AGP will be capable of providing pointing, focusing, an wavefront optical path difference, as well as aberration information at both helium neon (He-Ne) and CO2 wavelengths. It is designed to allow the laser beams to be aligned to any position within a 1 cm cube to a tolerance of 10 micrometers.

UV Raman scattering measurements in a Mach 2 H2-air flame for assessment of CFD models

NASA Technical Reports Server (NTRS)

Cheng, T. S.; Wehrmeyer, J. A.; Pitz, R. W.; Jarrett, O., Jr.; Northam, G. B.

1991-01-01

An UV narrowband tunable excimer laser is used for spontaneous Raman scattering measurements in hydrogen diffusion flames. The UV Raman system is characterized by a repetition rate of about 100 Hz, a temporal resolution of about 20 ns, and a spatial resolution of about 0.4 mm. It is concluded that a single KrF excimer laser based on spontaneous Raman scattering in conjunction with laser-induced predissociative fluorescence is capable of measuring instantaneously and simultaneously major species (H2, O2, N2, H2O), minor species (OH), and temperature.

Development of a Pulsed 2-micron Laser Transmitter for CO2 Sensing from Space

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong; Bai, Yingxin; Petros, Mulugeta; Menzies, Robert T.

2011-01-01

NASA Langley Research Center (LaRC), in collaboration with NASA Jet Propulsion Laboratory (JPL), is engaged in the development and demonstration of a highly efficient, versatile, 2-micron pulsed laser that can be used in a pulsed Differential Absorption Lidar (DIAL)/Integrated Path Differential Absorption (IPDA) instrument to make precise, high-resolution CO2 measurements to investigate sources, sinks, and fluxes of CO2. This laser transmitter will feature performance characteristics needed for an ASCENDS system that will be capable of delivering the CO2 measurement precision required by the Earth Science Decadal Survey (DS).

Resonator design and performance estimation for a space-based laser transmitter

NASA Astrophysics Data System (ADS)

Agrawal, Lalita; Bhardwaj, Atul; Pal, Suranjan; Kamalakar, J. A.

2006-12-01

Development of a laser transmitter for space applications is a highly challenging task. The laser must be rugged, reliable, lightweight, compact and energy efficient. Most of these features are inherently achieved by diode pumping of solid state lasers. Overall system reliability can further be improved by appropriate optical design of the laser resonator besides selection of suitable electro-optical and opto-mechanical components. This paper presents the design details and the theoretically estimated performance of a crossed-porro prism based, folded Z-shaped laser resonator. A symmetrically pumped Nd: YAG laser rod of 3 mm diameter and 60 mm length is placed in the gain arm with total input peak power of 1800 W from laser diode arrays. Electro-optical Q-switching is achieved through a combination of a polarizer, a fractional waveplate and LiNbO 3 Q-switch crystal (9 x 9 x 25 mm) placed in the feedback arm. Polarization coupled output is obtained by optimizing azimuth angle of quarter wave plate placed in the gain arm. Theoretical estimation of laser output energy and pulse width has been carried out by varying input power levels and resonator length to analyse the performance tolerances. The designed system is capable of meeting the objective of generating laser pulses of 10 ns duration and 30 mJ energy @ 10 Hz.

Keratin film ablation for the fabrication of brick and mortar skin structure using femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Haq, Bibi Safia; Khan, Hidayat Ullah; Dou, Yuehua; Alam, Khan; Attaullah, Shehnaz; Zari, Islam

2015-09-01

The patterning of thin keratin films has been explored to manufacture model skin surfaces based on the "bricks and mortar" view of the relationship between keratin and lipids. It has been demonstrated that laser light is capable of preparing keratin-based "bricks and mortar" wall structure as in epidermis, the outermost layer of the human skin. "Bricks and mortar" pattern in keratin films has been fabricated using an ArF excimer laser (193 nm wavelength) and femtosecond laser (800 and 400 nm wavelength). Due to the very low ablation threshold of keratin, femtosecond laser systems are practical for laser processing of proteins. These model skin structures are fabricated for the first time that will help to produce potentially effective moisturizing products for the protection of skin from dryness, diseases and wrinkles.

An experimental study of laser-supported plasmas for laser propulsion: Center director's discretionary fund project DFP-82-33

NASA Technical Reports Server (NTRS)

Eskridge, R. H.; Mccay, T. D.; Vanzandt, D. M.

1987-01-01

The rudiments of a rocket thruster, which receives its enthalpy from an energy source which is remotely beamed from a laser, is described. An experimental study, now partially complete, is discussed which will eventually provide a detailed understanding of the physics for assessing the feasibility of using hydrogen plasmas for accepting and converting this energy to enthalpy. A plasma ignition scheme which uses a pulsed CO2 laser was develped and the properites of the ignition spark documented, including breakdown intensities in hydrogen. A complete diagnostic system capable of determining plasma temperature and the plasma absorptivitiy for subsequent steady-state absorption of a high power CO2 laser beam are developed and demonstrative use is discussed for the preliminary case study, a two atmosphere laser supported argon plasma.

Hard copies for digital medical images: an overview

NASA Astrophysics Data System (ADS)

Blume, Hartwig R.; Muka, Edward

1995-04-01

This paper is a condensed version of an invited overview on the technology of film hard-copies used in radiology. Because the overview was given to an essentially nonmedical audience, the reliance on film hard-copies in radiology is outlined in greater detail. The overview is concerned with laser image recorders generating monochrome prints on silver-halide films. The basic components of laser image recorders are sketched. The paper concentrates on the physical parameters - characteristic function, dynamic range, digitization resolution, modulation transfer function, and noise power spectrum - which define image quality and information transfer capability of the printed image. A preliminary approach is presented to compare the printed image quality with noise in the acquired image as well as with the noise of state-of- the-art cathode-ray-tube display systems. High-performance laser-image- recorder/silver-halide-film/light-box systems are well capable of reproducing acquired radiologic information. Most recently development was begun toward a display function standard for soft-copy display systems to facilitate similarity of image presentation between different soft-copy displays as well as between soft- and hard-copy displays. The standard display function is based on perceptional linearization. The standard is briefly reviewed to encourage the printer industry to adopt it, too.

Requirements and Capabilities for Fielding Cryogenic DT-Containing Fill-Tube Targets for Direct-Drive Experiments on OMEGA

DOE PAGES

Harding, D. R.; Ulreich, J.; Wittman, M. D.; ...

2017-12-06

Improving the performance of direct-drive cryogenic targets at the Omega Laser Facility requires the development of a new cryogenic system to (i) field non permeable targets with a fill tube, and (ii) provide a clean environment around the target. This capability is to demonstrate that imploding a scaled-down version of the direct-drive–ignition target for the National Ignition Facility (NIF) on the OMEGA laser will generate the hot-spot pressure that is needed for ignition; this will justify future cryogenic direct-drive experiments on the NIF. The paper describes the target, the cryogenic equipment that is being constructed to achieve this goal, andmore » the proposed target delivery process. Thermal calculations, fill-tube–based target designs, and structural/vibrational analyses are provided to demonstrate the credibility of the design. This new design will include capabilities not available (or possible) with the existing OMEGA cryogenic system, with the emphasis being to preserve a pristinely clean environment around the target, and to provide upgraded diagnostics to characterize both the ice layer and the target’s surface. The conceptual design is complete and testing of prototypes and subcomponents is underway. The rationale and capabilities of the new design are discussed.« less

Requirements and Capabilities for Fielding Cryogenic DT-Containing Fill-Tube Targets for Direct-Drive Experiments on OMEGA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harding, D. R.; Ulreich, J.; Wittman, M. D.

Improving the performance of direct-drive cryogenic targets at the Omega Laser Facility requires the development of a new cryogenic system to (i) field non permeable targets with a fill tube, and (ii) provide a clean environment around the target. This capability is to demonstrate that imploding a scaled-down version of the direct-drive–ignition target for the National Ignition Facility (NIF) on the OMEGA laser will generate the hot-spot pressure that is needed for ignition; this will justify future cryogenic direct-drive experiments on the NIF. The paper describes the target, the cryogenic equipment that is being constructed to achieve this goal, andmore » the proposed target delivery process. Thermal calculations, fill-tube–based target designs, and structural/vibrational analyses are provided to demonstrate the credibility of the design. This new design will include capabilities not available (or possible) with the existing OMEGA cryogenic system, with the emphasis being to preserve a pristinely clean environment around the target, and to provide upgraded diagnostics to characterize both the ice layer and the target’s surface. The conceptual design is complete and testing of prototypes and subcomponents is underway. The rationale and capabilities of the new design are discussed.« less

Amplifying modeling for broad bandwidth pulse in Nd:glass based on hybrid-broaden mechanism

NASA Astrophysics Data System (ADS)

Su, J.; Liu, L.; Luo, B.; Wang, W.; Jing, F.; Wei, X.; Zhang, X.

2008-05-01

In this paper, the cross relaxation time is proposed to combine the homogeneous and inhomogeneous broaden mechanism for broad bandwidth pulse amplification model. The corresponding velocity equation, which can describe the response of inverse population on upper and low energy level of gain media to different frequency of pulse, is also put forward. The gain saturation and energy relaxation effect are also included in the velocity equation. Code named CPAP has been developed to simulate the amplifying process of broad bandwidth pulse in multi-pass laser system. The amplifying capability of multi-pass laser system is evaluated and gain narrowing and temporal shape distortion are also investigated when bandwidth of pulse and cross relaxation time of gain media are different. Results can benefit the design of high-energy PW laser system in LFRC, CAEP.

Optical workstation with concurrent, independent multiphoton imaging and experimental laser microbeam capabilities

PubMed Central

Wokosin, David L.; Squirrell, Jayne M.; Eliceiri, Kevin W.; White, John G.

2008-01-01

Experimental laser microbeam techniques have become established tools for studying living specimens. A steerable, focused laser beam may be used for a variety of experimental manipulations such as laser microsurgery, optical trapping, localized photolysis of caged bioactive probes, and patterned photobleaching. Typically, purpose-designed experimental systems have been constructed for each of these applications. In order to assess the consequences of such experimental optical interventions, long-term, microscopic observation of the specimen is often required. Multiphoton excitation, because of its ability to obtain high-contrast images from deep within a specimen with minimal phototoxic effects, is a preferred technique for in vivo imaging. An optical workstation is described that combines the functionality of an experimental optical microbeam apparatus with a sensitive multiphoton imaging system designed for use with living specimens. Design considerations are discussed and examples of ongoing biological applications are presented. The integrated optical workstation concept offers advantages in terms of flexibility and versatility relative to systems implemented with separate imaging and experimental components. PMID:18607511

Analysis of a 10 megawatt space-based solar-pumped neodymium laser system

NASA Technical Reports Server (NTRS)

Kurweg, U. H.

1984-01-01

A ten megawatt solar-pumped continuous liquid laser system for space applications is examined. It is found that a single inflatable mirror of 434 m diameter used in conjunction with a conical secondary concentrator is sufficient to side pump a liquid neodymium lasant in an annular tube of 6 m length and 1 m outer and 0.8 m inner diameter. About one fourth of intercepted radiation converging on the laser tube is absorbed and one fifth of this radiation is effective in populating the upper levels. The liquid lasant is flowed through the annular laser cavity at 1.9 m/s and is cooled via a heat exchanger and a large radiator surface comparable in size to the concentrating mirror. The power density of incident light within the lasant of approximately 68 watt/cu cm required for cw operation is exceeded in the present annular configuration. Total system weight corresponds to 20,500 kg and is thus capable of being transported to near Earth orbit by a single shuttle flight.

Optical workstation with concurrent, independent multiphoton imaging and experimental laser microbeam capabilities

NASA Astrophysics Data System (ADS)

Wokosin, David L.; Squirrell, Jayne M.; Eliceiri, Kevin W.; White, John G.

2003-01-01

Experimental laser microbeam techniques have become established tools for studying living specimens. A steerable, focused laser beam may be used for a variety of experimental manipulations such as laser microsurgery, optical trapping, localized photolysis of caged bioactive probes, and patterned photobleaching. Typically, purpose-designed experimental systems have been constructed for each of these applications. In order to assess the consequences of such experimental optical interventions, long-term, microscopic observation of the specimen is often required. Multiphoton excitation, because of its ability to obtain high-contrast images from deep within a specimen with minimal phototoxic effects, is a preferred technique for in vivo imaging. An optical workstation is described that combines the functionality of an experimental optical microbeam apparatus with a sensitive multiphoton imaging system designed for use with living specimens. Design considerations are discussed and examples of ongoing biological applications are presented. The integrated optical workstation concept offers advantages in terms of flexibility and versatility relative to systems implemented with separate imaging and experimental components.

Automated ablation of dental composite using an IR pulsed laser coupled to a plume emission spectral feedback system.

PubMed

Jang, Andrew T; Chan, Kenneth H; Fried, Daniel

2017-09-01

The purpose of this study is to assemble a laser system for the selective removal of dental composite from tooth surfaces, that is feasible for clinical use incorporating a spectral feedback system, a scanning system, articulating arm and a clinical hand-piece, and evaluate the performance of that system on extracted teeth. Ten extracted teeth were collected and small fillings were placed on the occlusal surface of each tooth. A clinical system featuring a CO 2 laser operating at 50 Hz and spectral optical feedback was used to remove the composite. Removal was confirmed using a cross polarized optical coherence tomography (CP-OCT) system designed for clinical use. The system was capable of rapidly removing composite from small preparations on tooth occlusal surfaces with a mean loss of enamel of less than 20 μm. We have demonstrated that spectral feedback can be successfully employed in an automated system for composite removal by incorporating dual photodiodes and a galvanometer controlled CO 2 laser. Additionally, the use of registered OCT images presents as a viable method for volumetric benchmarking. Overall, this study represents the first implementation of spectral feedback into a clinical hand-piece and serves as a benchmark for a future clinical study. Lasers Surg. Med. 49:658-665, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Nanometer-scale characterization of laser-driven compression, shocks, and phase transitions, by x-ray scattering using free electron lasers

DOE PAGES

Kluge, T.; Rödel, C.; Rödel, M.; ...

2017-10-23

In this paper, we study the feasibility of using small angle X-ray scattering (SAXS) as a new experimental diagnostic for intense laser-solid interactions. By using X-ray pulses from a hard X-ray free electron laser, we can simultaneously achieve nanometer and femtosecond resolution of laser-driven samples. This is an important new capability for the Helmholtz international beamline for extreme fields at the high energy density endstation currently built at the European X-ray free electron laser. We review the relevant SAXS theory and its application to transient processes in solid density plasmas and report on first experimental results that confirm the feasibilitymore » of the method. Finally, we present results of two test experiments where the first experiment employs ultra-short laser pulses for studying relativistic laser plasma interactions, and the second one focuses on shock compression studies with a nanosecond laser system.« less

Nanometer-scale characterization of laser-driven compression, shocks, and phase transitions, by x-ray scattering using free electron lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kluge, T.; Rödel, C.; Rödel, M.

In this paper, we study the feasibility of using small angle X-ray scattering (SAXS) as a new experimental diagnostic for intense laser-solid interactions. By using X-ray pulses from a hard X-ray free electron laser, we can simultaneously achieve nanometer and femtosecond resolution of laser-driven samples. This is an important new capability for the Helmholtz international beamline for extreme fields at the high energy density endstation currently built at the European X-ray free electron laser. We review the relevant SAXS theory and its application to transient processes in solid density plasmas and report on first experimental results that confirm the feasibilitymore » of the method. Finally, we present results of two test experiments where the first experiment employs ultra-short laser pulses for studying relativistic laser plasma interactions, and the second one focuses on shock compression studies with a nanosecond laser system.« less

Monolithic crystalline cladding microstructures for efficient light guiding and beam manipulation in passive and active regimes.

PubMed

Jia, Yuechen; Cheng, Chen; Vázquez de Aldana, Javier R; Castillo, Gabriel R; Rabes, Blanca del Rosal; Tan, Yang; Jaque, Daniel; Chen, Feng

2014-08-07

Miniature laser sources with on-demand beam features are desirable devices for a broad range of photonic applications. Lasing based on direct-pump of miniaturized waveguiding active structures offers a low-cost but intriguing solution for compact light-emitting devices. In this work, we demonstrate a novel family of three dimensional (3D) photonic microstructures monolithically integrated in a Nd:YAG laser crystal wafer. They are produced by the femtosecond laser writing, capable of simultaneous light waveguiding and beam manipulation. In these guiding systems, tailoring of laser modes by both passive/active beam splitting and ring-shaped transformation are achieved by an appropriate design of refractive index patterns. Integration of graphene thin-layer as saturable absorber in the 3D laser structures allows for efficient passive Q-switching of tailored laser radiations which may enable miniature waveguiding lasers for broader applications. Our results pave a way to construct complex integrated passive and active laser circuits in dielectric crystals by using femtosecond laser written monolithic photonic chips.

Good Vibrations

NASA Technical Reports Server (NTRS)

2001-01-01

A Small Business Innovation Research (SBIR) sponsorship from NASA's Dryden Flight Research Center, assisted MetroLaser, of Irvine, California, in the development of a self-aligned laser vibrometer system. VibroMet, capable of measuring surface vibrations in a variety of industries, provides information on the structural integrity and acoustical characteristics of manufactured products. This low-cost, easy-to-use sensor performs vibration measurement from distances of up to three meters without the need for adjustment. The laser beam is simply pointed at the target and the system then uses a compact laser diode to illuminate the surface and to subsequently analyze the reflected light. The motion of the surface results in a Doppler shift that is measured with very high precision. VibroMet is considered one of the many behind-the-scenes tools that can be relied on to assure the quality, reliability and safety of everything from airplane panels to disk brakes

Laser-Mechanical Drilling for Geothermal Energy: Low-Contact Drilling Technology to Enable Economical EGS Wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2010-01-15

Broad Funding Opportunity Announcement Project: Foro Energy is developing a unique capability and hardware system to transmit high power lasers over long distances via fiber optic cables. This laser power is integrated with a mechanical drilling bit to enable rapid and sustained penetration of hard rock formations too costly to drill with mechanical drilling bits alone. The laser energy that is directed at the rock basically softens the rock, allowing the mechanical bit to more easily remove it. Foro Energy’s laser-assisted drill bits have the potential to be up to 10 times more economical than conventional hard-rock drilling technologies, makingmore » them an effective way to access the U.S. energy resources currently locked under hard rock formations.« less

Detection of Interference Phase by Digital Computation of Quadrature Signals in Homodyne Laser Interferometry

PubMed Central

Rerucha, Simon; Buchta, Zdenek; Sarbort, Martin; Lazar, Josef; Cip, Ondrej

2012-01-01

We have proposed an approach to the interference phase extraction in the homodyne laser interferometry. The method employs a series of computational steps to reconstruct the signals for quadrature detection from an interference signal from a non-polarising interferometer sampled by a simple photodetector. The complexity trade-off is the use of laser beam with frequency modulation capability. It is analytically derived and its validity and performance is experimentally verified. The method has proven to be a feasible alternative for the traditional homodyne detection since it performs with comparable accuracy, especially where the optical setup complexity is principal issue and the modulation of laser beam is not a heavy burden (e.g., in multi-axis sensor or laser diode based systems). PMID:23202038

High-intensity laser-accelerated ion beam produced from cryogenic micro-jet target

DOE PAGES

Gauthier, M.; Kim, J. B.; Curry, C. B.; ...

2016-08-24

Here, we report on the successful operation of a newly developed cryogenic jet target at high intensity laser-irradiation. Using the frequency-doubled Titan short pulse laser system at Jupiter Laser Facility, Lawrence Livermore National Laboratory, we demonstrate the generation of a pure proton beam a with maximum energy of 2 MeV. Furthermore, we record a quasi-monoenergetic peak at 1.1 MeV in the proton spectrum emitted in the laser forward direction suggesting an alternative acceleration mechanism. Using a solid-density mixed hydrogen-deuterium target, we are also able to produce pure proton-deuteron ion beams. With its high purity, limited size, near-critical density, and high-repetitionmore » rate capability, this target is promising for future applications.« less

High-intensity laser-accelerated ion beam produced from cryogenic micro-jet target

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gauthier, M., E-mail: maxence.gauthier@stanford.edu; Kim, J. B.; Curry, C. B.

2016-11-15

We report on the successful operation of a newly developed cryogenic jet target at high intensity laser-irradiation. Using the frequency-doubled Titan short pulse laser system at Jupiter Laser Facility, Lawrence Livermore National Laboratory, we demonstrate the generation of a pure proton beam a with maximum energy of 2 MeV. Furthermore, we record a quasi-monoenergetic peak at 1.1 MeV in the proton spectrum emitted in the laser forward direction suggesting an alternative acceleration mechanism. Using a solid-density mixed hydrogen-deuterium target, we are also able to produce pure proton-deuteron ion beams. With its high purity, limited size, near-critical density, and high-repetition ratemore » capability, this target is promising for future applications.« less

A highly efficient and compact long pulse Nd:YAG rod laser with 540 J of pulse energy for welding application.

PubMed

Choubey, Ambar; Vishwakarma, S C; Misra, Pushkar; Jain, R K; Agrawal, D K; Arya, R; Upadhyaya, B N; Oak, S M

2013-07-01

We have developed an efficient and high average power flash lamp pumped long pulse Nd:YAG laser capable of generating 1 kW of average output power with maximum 540 J of single pulse energy and 20 kW of peak power. The laser pulse duration can be varied from 1 to 40 ms and repetition rate from 1 to 100 Hz. A compact and robust laser pump chamber and resonator was designed to achieve this high average and peak power. It was found that this laser system provides highest single pulse energy as compared to other long pulsed Nd:YAG laser systems of similar rating. A slope efficiency of 5.4% has been achieved, which is on higher side for typical lamp pumped solid-state lasers. This system will be highly useful in laser welding of materials such as aluminium and titanium. We have achieved 4 mm deep penetration welding of these metals under optimized conditions of output power, pulse energy, and pulse duration. The laser resonator was optimized to provide stable operation from single shot to 100 Hz of repetition rate. The beam quality factor was measured to be M(2) ~ 91 and pulse-to-pulse stability of ±3% for the multimode operation. The laser beam was efficiently coupled through an optical fiber of 600 μm core diameter and 0.22 numerical aperture with power transmission of 90%.

Beam shaping to provide round and square-shaped beams in optical systems of high-power lasers

NASA Astrophysics Data System (ADS)

Laskin, Alexander; Laskin, Vadim

2016-05-01

Optical systems of modern high-power lasers require control of irradiance distribution: round or square-shaped flat-top or super-Gaussian irradiance profiles are optimum for amplification in MOPA lasers and for thermal load management while pumping of crystals of solid-state ultra-short pulse lasers to control heat and minimize its impact on the laser power and beam quality while maximizing overall laser efficiency, variable profiles are also important in irradiating of photocathode of Free Electron lasers (FEL). It is suggested to solve the task of irradiance re-distribution using field mapping refractive beam shapers like piShaper. The operational principle of these devices presumes transformation of laser beam intensity from Gaussian to flat-top one with high flatness of output wavefront, saving of beam consistency, providing collimated output beam of low divergence, high transmittance, extended depth of field, negligible residual wave aberration, and achromatic design provides capability to work with ultra-short pulse lasers having broad spectrum. Using the same piShaper device it is possible to realize beams with flat-top, inverse Gauss or super Gauss irradiance distribution by simple variation of input beam diameter, and the beam shape can be round or square with soft edges. This paper will describe some design basics of refractive beam shapers of the field mapping type and optical layouts of their applying in optical systems of high-power lasers. Examples of real implementations and experimental results will be presented as well.

Development of an integrated automated retinal surgical laser system.

PubMed

Barrett, S F; Wright, C H; Oberg, E D; Rockwell, B A; Cain, C; Rylander, H G; Welch, A J

1996-01-01

Researchers at the University of Texas and the USAF Academy have worked toward the development of a retinal robotic laser system. The overall goal of this ongoing project is to precisely place and control the depth of laser lesions for the treatment of various retinal diseases such as diabetic retinopathy and retinal tears. Separate low speed prototype subsystems have been developed to control lesion depth using lesion reflectance feedback parameters and lesion placement using retinal vessels as tracking landmarks. Both subsystems have been successfully demonstrated in vivo on pigmented rabbits using an argon continuous wave laser. Preliminary testing on rhesus primate subjects have been accomplished with the CW argon laser and also the ultrashort pulse laser. Recent efforts have concentrated on combining the two subsystems into a single prototype capable of simultaneously controlling both lesion depth and placement. We have designated this combined system CALOSOS for Computer Aided Laser Optics System for Ophthalmic Surgery. Several interesting areas of study have developed in integrating the two subsystems: 1) "doughnut" shaped lesions that occur under certain combinations of laser power, spot size, and irradiation time complicating measurements of central lesion reflectance, 2) the optimal retinal field of view (FOV) to achieve both tracking and lesion parameter control, and 3) development of a hybrid analog/digital tracker using confocal reflectometry to achieve retinal tracking speeds of up to 100 dgs. This presentation will discuss these design issues of this clinically significant prototype system. Details of the hybrid prototype system are provided in "Hybrid Eye Tracking for Computer-Aided Retinal Surgery" at this conference. The paper will close with remaining technical hurdles to clear prior to testing the full-up clinical prototype system.

Analysis of Technology for Compact Coherent Lidar

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin

1997-01-01

In view of the recent advances in the area of solid state and semiconductor lasers has created new possibilities for the development of compact and reliable coherent lidars for a wide range of applications. These applications include: Automated Rendezvous and Capture, wind shear and clear air turbulence detection, aircraft wake vortex detection, and automobile collision avoidance. The work performed by the UAH personnel under this Delivery Order, concentrated on design and analyses of a compact coherent lidar system capable of measuring range and velocity of hard targets, and providing air mass velocity data. The following is the scope of this work. a. Investigate various laser sources and optical signal detection configurations in support of a compact and lightweight coherent laser radar to be developed for precision range and velocity measurements of hard and fuzzy targets. Through interaction with MSFC engineers, the most suitable laser source and signal detection technique that can provide a reliable compact and lightweight laser radar design will be selected. b. Analyze and specify the coherent laser radar system configuration and assist with its optical and electronic design efforts. Develop a system design including its optical layout design. Specify all optical components and provide the general requirements of the electronic subsystems including laser beam modulator and demodulator drivers, detector electronic interface, and the signal processor. c. Perform a thorough performance analysis to predict the system measurement range and accuracy. This analysis will utilize various coherent laser radar sensitivity formulations and different target models.

CO2 laser myringotomy with a hand-held otoscope and fiber optic delivery system: animal experimentation and preclinical trials

NASA Astrophysics Data System (ADS)

DeRowe, Ari; Ophir, Dov; Finkelstein, Y.; Katzir, Abraham

1993-07-01

CO2 laser myringotomy has previously been proven effective in patients with serous otitis media for short term aeration of the middle ear. However, the system based on a microscope and a coaxially aligned laser is cumbersome and expensive. Also, conventional optical fibers do not transmit CO2 laser energy ((lambda) equals 10.6 micrometers ). We have developed a silver halide optical fiber of diameter 0.9 mm and lengths of several meters, with high transmission at 10.6 micrometers . Using a hand held otoscope coupled to a fiberoptic delivery system CO2 laser myringotomies were performed first in guinea pigs and then in humans. In the animal model the feasibility of the procedure was proven. Different irradiation parameters were studied and a `dose dependent' relationship was found between the total energy used and the duration of a patent myringotomy. This system was used to perform CO2 laser myringotomies under local anesthesia in five patients with serous otitis media and conductive hearing loss. None of the patients complained of discomfort and no scarring was noted. All patients had subjective and audiometric documentation of hearing improvement. The average duration of a patent myringotomy was 21 days. In two patients the effusion recurred. CO2 laser myringotomy utilizing a hand held otoscope coupled to an optical fiber capable of transmitting CO2 laser energy may prove simple and effective in the treatment of serous otitis media.

Laser Based Color Film Recorder System With GaAs Microlaser

NASA Astrophysics Data System (ADS)

Difrancesco, David J.

1989-07-01

In 1984 Pixar's research and development group built and applied to the motion-picture arts at Lucasfilm's ILM facility a three color laser based film scanner/recorder system. The digital film printer is capable of reading and writing 35mm film formats on a variety of film stocks. The system has been used in award-winning special-effects work, and has been operated in a normal production environment since that time. The primary objective was to develop a full color high resolution system, free from scan artifacts, enabling traditionally photographed motion-picture film to be inter-cut with digital raster image photography. Its use is applied to the art of blue-screen traveling-matte cinematography for motion pic-ture special effects. The system was designed using the Pixar Image Computer and conventional gas laser technology as the illumination source. This paper will discuss recent experimental work in the application of GaAs microlaser technology to a digital film printing system of the future.

Multiple layer optical memory system using second-harmonic-generation readout

DOEpatents

Boyd, Gary T.; Shen, Yuen-Ron

1989-01-01

A novel optical read and write information storage system is described which comprises a radiation source such as a laser for writing and illumination, the radiation source being capable of radiating a preselected first frequency; a storage medium including at least one layer of material for receiving radiation from the radiation source and capable of being surface modified in response to said radiation source when operated in a writing mode and capable of generating a pattern of radiation of the second harmonic of the preselected frequency when illuminated by the radiation source at the preselected frequency corresponding to the surface modifications on the storage medium; and a detector to receive the pattern of second harmonic frequency generated.

Numerical study on statistical properties of speckle pattern in laser projection display based on human eye model

NASA Astrophysics Data System (ADS)

Cui, Zhe; Wang, Anting; Ma, Qianli; Ming, Hai

2013-12-01

In this paper, the laser speckle pattern on human retina for a laser projection display is simulated. By introducing a specific eye model `Indiana Eye', the statistical properties of the laser speckle are numerical investigated. The results show that the aberrations of human eye (mostly spherical and chromatic) will decrease the speckle contrast felt by people. When the wavelength of the laser source is 550 nm (green), people will feel the strongest speck pattern and the weakest when the wavelength is 450 nm (blue). Myopia and hyperopia will decrease the speckle contrast by introducing large spherical aberrations. Although aberration is good for speckle reduction, but it will degrade the imaging capability of the eye. The results show that laser source (650 nm) will have the best image quality on the retina. At last, we compare the human eye with an aberration-free imaging system. Both the speckle contrast and the image quality appear different behavior in these two imaging systems. The results are useful when a standardized measurement procedure for speckle contrast needs to be built.

Laser fluorescence bronchoscope for localization of occult lung tumors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Profio, A.E.; Doiron, D.R.; King, E.G.

1979-11-01

A system for imaging occult bronchogenic carcinoma by the fluorescence of previously-injected, tumor-specific compound hematoporphyrin-derivative has been assembled and successfully used to locate a tumor l mm thick. The violet excitation source is a krypton ion laser coupled to fused quartz fiber light conductor. An electrostatic image intensifier attached to a standard flexible fiberoptic bronchoscope provides a bright image even at relatively low irradiance. A red secondary filter rejects most reflected background and autofluorescence. Sensitivity and contrast capability of the system should permit detection of a tumor less than 0.1 mm thick.

Field tests of a handheld laser communications/position-finding binocular system

NASA Astrophysics Data System (ADS)

Chan, Victor J.; Rivers, Michael D.; Harris, Amy L.

1998-01-01

Lasers provide a means for transmitting larger quantities of data at higher rates than conventional radio frequency devices and can be utilized during radio silent operations on the battle field. A forward scout needs to be able to observe the positions of various targets and relay that information back to a tactical operations command center in a covert manner. The BiCom device built by Trex Communications provides laser ranging, azimuth and elevation angle to a target, GPS position information, data storage and transmit capability, and full duplex audio transmission capability, all in a 3 kg hand held package. The communication channel utilizes an eye safe lasercom transceiver for covert voice or data transfer at 100 kbps at distances of up to 5 km. The information gathered electronically by the unit is sufficient to calculate the actual GPS positions or military grid coordinates of the observed targets. Several dozen targets can be stored in memory for later transmission via lasercom. Field tests were conducted by US Army personnel to evaluate these units and compare the results with conventional means of target position determination and data transfer. A description of the system and results of these tests are presented.

Numerical aperture limits on efficient ball lens coupling of laser diodes to single-mode fibers with defocus to balance spherical aberration

NASA Technical Reports Server (NTRS)

Wilson, R. Gale

1994-01-01

The potential capabilities and limitations of single ball lenses for coupling laser diode radiation to single-mode optical fibers have been analyzed; parameters important to optical communications were specifically considered. These parameters included coupling efficiency, effective numerical apertures, lens radius, lens refractive index, wavelength, magnification in imaging the laser diode on the fiber, and defocus to counterbalance spherical aberration of the lens. Limiting numerical apertures in object and image space were determined under the constraint that the lens perform to the Rayleigh criterion of 0.25-wavelength (Strehl ratio = 0.80). The spherical aberration-defocus balance to provide an optical path difference of 0.25 wavelength units was shown to define a constant coupling efficiency (i.e., 0.56). The relative numerical aperture capabilities of the ball lens were determined for a set of wavelengths and associated fiber-core diameters of particular interest for single-mode fiber-optic communication. The results support general continuing efforts in the optical fiber communications industry to improve coupling links within such systems with emphasis on manufacturing simplicity, system packaging flexibility, relaxation of assembly alignment tolerances, cost reduction of opto-electronic components and long term reliability and stability.

Laser pulse coded signal frequency measuring device based on DSP and CPLD

NASA Astrophysics Data System (ADS)

Zhang, Hai-bo; Cao, Li-hua; Geng, Ai-hui; Li, Yan; Guo, Ru-hai; Wang, Ting-feng

2011-06-01

Laser pulse code is an anti-jamming measures used in semi-active laser guided weapons. On account of the laser-guided signals adopting pulse coding mode and the weak signal processing, it need complex calculations in the frequency measurement process according to the laser pulse code signal time correlation to meet the request in optoelectronic countermeasures in semi-active laser guided weapons. To ensure accurately completing frequency measurement in a short time, it needed to carry out self-related process with the pulse arrival time series composed of pulse arrival time, calculate the signal repetition period, and then identify the letter type to achieve signal decoding from determining the time value, number and rank number in a signal cycle by Using CPLD and DSP for signal processing chip, designing a laser-guided signal frequency measurement in the pulse frequency measurement device, improving the signal processing capability through the appropriate software algorithms. In this article, we introduced the principle of frequency measurement of the device, described the hardware components of the device, the system works and software, analyzed the impact of some system factors on the accuracy of the measurement. The experimental results indicated that this system improve the accuracy of the measurement under the premise of volume, real-time, anti-interference, low power of the laser pulse frequency measuring device. The practicality of the design, reliability has been demonstrated from the experimental point of view.

An all fiber-optic multi-parameter structure health monitoring system

DOE PAGES

Hu, Chennan; Yu, Zhihao; Wang, Anbo

2016-08-24

In this article, we present an all fiber-optics based multi-parameter structure health monitoring system, which is able to monitor strain, temperature, crack and thickness of metal structures. This system is composed of two optical fibers, one for laser-acoustic excitation and the other for acoustic detection. A nano-second 1064 nm pulse laser was used for acoustic excitation and a 2 mm fiber Bragg grating was used to detect the acoustic vibration. The feasibility of this system was demonstrated on an aluminum test piece by the monitoring of the temperature, strain and thickness changes, as well as the appearance of an artificialmore » crack. The multiplexing capability of this system was also preliminarily demonstrated.« less

An all fiber-optic multi-parameter structure health monitoring system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Chennan; Yu, Zhihao; Wang, Anbo

In this article, we present an all fiber-optics based multi-parameter structure health monitoring system, which is able to monitor strain, temperature, crack and thickness of metal structures. This system is composed of two optical fibers, one for laser-acoustic excitation and the other for acoustic detection. A nano-second 1064 nm pulse laser was used for acoustic excitation and a 2 mm fiber Bragg grating was used to detect the acoustic vibration. The feasibility of this system was demonstrated on an aluminum test piece by the monitoring of the temperature, strain and thickness changes, as well as the appearance of an artificialmore » crack. The multiplexing capability of this system was also preliminarily demonstrated.« less

A real-time laser feedback control method for the three-wave laser source used in the polarimeter-interferometer diagnostic on Joint-TEXT tokamak

NASA Astrophysics Data System (ADS)

Xiong, C. Y.; Chen, J.; Li, Q.; Liu, Y.; Gao, L.

2014-12-01

A three-wave laser polarimeter-interferometer, equipped with three independent far-infrared laser sources, has been developed on Joint-TEXT (J-TEXT) tokamak. The diagnostic system is capable of high-resolution temporal and phase measurement of the Faraday angle and line-integrated density. However, for long-term operation (>10 min), the free-running lasers can lead to large drifts of the intermediate frequencies (˜100-˜500 kHz/10 min) and decay of laser power (˜10%-˜20%/10 min), which act to degrade diagnostic performance. In addition, these effects lead to increased maintenance cost and limit measurement applicability to long pulse/steady state experiments. To solve this problem, a real-time feedback control method of the laser source is proposed. By accurately controlling the length of each laser cavity, both the intermediate frequencies and laser power can be simultaneously controlled: the intermediate frequencies are controlled according to the pre-set values, while the laser powers are maintained at an optimal level. Based on this approach, a real-time feedback control system has been developed and applied on J-TEXT polarimeter-interferometer. Long-term (theoretically no time limit) feedback of intermediate frequencies (maximum change less than ±12 kHz) and laser powers (maximum relative power change less than ±7%) has been successfully achieved.

A real-time laser feedback control method for the three-wave laser source used in the polarimeter-interferometer diagnostic on Joint-TEXT tokamak.

PubMed

Xiong, C Y; Chen, J; Li, Q; Liu, Y; Gao, L

2014-12-01

A three-wave laser polarimeter-interferometer, equipped with three independent far-infrared laser sources, has been developed on Joint-TEXT (J-TEXT) tokamak. The diagnostic system is capable of high-resolution temporal and phase measurement of the Faraday angle and line-integrated density. However, for long-term operation (>10 min), the free-running lasers can lead to large drifts of the intermediate frequencies (∼100-∼500 kHz/10 min) and decay of laser power (∼10%-∼20%/10 min), which act to degrade diagnostic performance. In addition, these effects lead to increased maintenance cost and limit measurement applicability to long pulse/steady state experiments. To solve this problem, a real-time feedback control method of the laser source is proposed. By accurately controlling the length of each laser cavity, both the intermediate frequencies and laser power can be simultaneously controlled: the intermediate frequencies are controlled according to the pre-set values, while the laser powers are maintained at an optimal level. Based on this approach, a real-time feedback control system has been developed and applied on J-TEXT polarimeter-interferometer. Long-term (theoretically no time limit) feedback of intermediate frequencies (maximum change less than ±12 kHz) and laser powers (maximum relative power change less than ±7%) has been successfully achieved.

Lasing by driven atoms-cavity system in collective strong coupling regime.

PubMed

Sawant, Rahul; Rangwala, S A

2017-09-12

The interaction of laser cooled atoms with resonant light is determined by the natural linewidth of the excited state. An optical cavity is another optically resonant system where the loss from the cavity determines the resonant optical response of the system. The near resonant combination of an optical Fabry-Pérot cavity with laser cooled and trapped atoms couples two distinct optical resonators via light and has great potential for precision measurements and the creation of versatile quantum optics systems. Here we show how driven magneto-optically trapped atoms in collective strong coupling regime with the cavity leads to lasing at a frequency red detuned from the atomic transition. Lasing is demonstrated experimentally by the observation of a lasing threshold accompanied by polarization and spatial mode purity, and line-narrowing in the outcoupled light. Spontaneous emission into the cavity mode by the driven atoms stimulates lasing action, which is capable of operating as a continuous wave laser in steady state, without a seed laser. The system is modeled theoretically, and qualitative agreement with experimentally observed lasing is seen. Our result opens up a range of new measurement possibilities with this system.

Rare Earth Doped IR Fiber Lasers For Medical Applications

NASA Astrophysics Data System (ADS)

Esterowitz, Leon; Allen, Roger

1989-06-01

Trivalent rare earth doped lasers in fluorozirconate glasses and fibers that lase between 2 and 3 μm are reviewed. There have been a large number of laser-fiber optic systems below 2pm developed for clinical microsurgery at a variety of sites. The required flexibility of the fiber optic waveguide varies with the clinical use, such as: intraocular (through a small diameter rigid tube), endoscopically accessible pulmonary and gastric mucosa (through a port of a fiber-optic endoscope of intermediate flexibility), and intra-arterial (as an integral part of a flexible catheter, which in the case of the coronaries must be very flexible so as to negotiate abrupt bends and bifurcations without damage to the vessels). Laser energy absorbed by tissue is capable of coagulation of tissue (denaturation of structural proteins), melting of fatty deposits or other structures (solid or gel to liquid phase transitions), as well as direct breakage of chemical bonds by high energy photons. It is of general interest to develop a pulsed laser system transmitted through flexible fiber optics that is capable of precise ablation of targeted tissue with minimal damage to the remaining tissue. Ideally, the device should be able to ablate any tissue because of the general absorptive properties of tissue, and not a specific chromophore such as melanin or hemoglobin, the concentration of which varies widely among tissues. Two obvious ubiquitous chromophores have been widely discussed: 1) proteins and nucleic acids whose high concentration and absorption coefficients lead to strong tissue absorption in the ultraviolet and 2) water whose strong infrared absorption bands have been widely utilized in CO2 laser surgery. Non-linear absorption occurring at very high power densities (~1 GW/cm2) has been shown to be very effective for non-invasive ocular (an optically transparent field) microsurgery at the image plane of a slit lamp, but this approach appears impractical in fiber optic systems because of similar non-linear damage mechanisms within the fiber.

Autonomous docking ground demonstration (category 3)

NASA Technical Reports Server (NTRS)

Lamkin, Steve L.; Eick, Richard E.; Baxter, James M.; Boyd, M. G.; Clark, Fred D.; Lee, Thomas Q.; Othon, L. T.; Prather, Joseph L.; Spehar, Peter T.; Teders, Rebecca J.

1991-01-01

The NASA Johnson Space Center (JSC) is involved in the development of an autonomous docking ground demonstration. The demonstration combines the technologies, expertise and facilities of the JSC Tracking and Communications Division (EE), Structures and Mechanics Division (ES), and the Navigation, Guidance and Control Division (EG) and their supporting contractors. The autonomous docking ground demonstration is an evaluation of the capabilities of the laser sensor system to support the docking phase (12ft to contact) when operated in conjunction with the Guidance, Navigation and Control Software. The docking mechanism being used was developed for the Apollo Soyuz Test Program. This demonstration will be conducted using the Six-Degrees of Freedom (6-DOF) Dynamic Test System (DTS). The DTS environment simulates the Space Station Freedom as the stationary or target vehicle and the Orbiter as the active or chase vehicle. For this demonstration the laser sensor will be mounted on the target vehicle and the retroreflectors on the chase vehicle. This arrangement was used to prevent potential damage to the laser. The sensor system. GN&C and 6-DOF DTS will be operated closed-loop. Initial condition to simulate vehicle misalignments, translational and rotational, will be introduced within the constraints of the systems involved. Detailed description of each of the demonstration components (e.g., Sensor System, GN&C, 6-DOF DTS and supporting computer configuration) including their capabilities and limitations will be discussed. A demonstration architecture drawing and photographs of the test configuration will be presented.

Autonomous docking ground demonstration (category 3)

NASA Astrophysics Data System (ADS)

Lamkin, Steve L.; Eick, Richard E.; Baxter, James M.; Boyd, M. G.; Clark, Fred D.; Lee, Thomas Q.; Othon, L. T.; Prather, Joseph L.; Spehar, Peter T.; Teders, Rebecca J.

The NASA Johnson Space Center (JSC) is involved in the development of an autonomous docking ground demonstration. The demonstration combines the technologies, expertise and facilities of the JSC Tracking and Communications Division (EE), Structures and Mechanics Division (ES), and the Navigation, Guidance and Control Division (EG) and their supporting contractors. The autonomous docking ground demonstration is an evaluation of the capabilities of the laser sensor system to support the docking phase (12ft to contact) when operated in conjunction with the Guidance, Navigation and Control Software. The docking mechanism being used was developed for the Apollo Soyuz Test Program. This demonstration will be conducted using the Six-Degrees of Freedom (6-DOF) Dynamic Test System (DTS). The DTS environment simulates the Space Station Freedom as the stationary or target vehicle and the Orbiter as the active or chase vehicle. For this demonstration the laser sensor will be mounted on the target vehicle and the retroreflectors on the chase vehicle. This arrangement was used to prevent potential damage to the laser. The sensor system. GN&C and 6-DOF DTS will be operated closed-loop. Initial condition to simulate vehicle misalignments, translational and rotational, will be introduced within the constraints of the systems involved. Detailed description of each of the demonstration components (e.g., Sensor System, GN&C, 6-DOF DTS and supporting computer configuration) including their capabilities and limitations will be discussed. A demonstration architecture drawing and photographs of the test configuration will be presented.

Evaluation and correction for optical scattering variations in laser speckle rheology of biological fluids.

PubMed

Hajjarian, Zeinab; Nadkarni, Seemantini K

2013-01-01

Biological fluids fulfill key functionalities such as hydrating, protecting, and nourishing cells and tissues in various organ systems. They are capable of these versatile tasks owing to their distinct structural and viscoelastic properties. Characterizing the viscoelastic properties of bio-fluids is of pivotal importance for monitoring the development of certain pathologies as well as engineering synthetic replacements. Laser Speckle Rheology (LSR) is a novel optical technology that enables mechanical evaluation of tissue. In LSR, a coherent laser beam illuminates the tissue and temporal speckle intensity fluctuations are analyzed to evaluate mechanical properties. The rate of temporal speckle fluctuations is, however, influenced by both optical and mechanical properties of tissue. Therefore, in this paper, we develop and validate an approach to estimate and compensate for the contributions of light scattering to speckle dynamics and demonstrate the capability of LSR for the accurate extraction of viscoelastic moduli in phantom samples and biological fluids of varying optical and mechanical properties.

Evaluation and Correction for Optical Scattering Variations in Laser Speckle Rheology of Biological Fluids

PubMed Central

Hajjarian, Zeinab; Nadkarni, Seemantini K.

2013-01-01

Biological fluids fulfill key functionalities such as hydrating, protecting, and nourishing cells and tissues in various organ systems. They are capable of these versatile tasks owing to their distinct structural and viscoelastic properties. Characterizing the viscoelastic properties of bio-fluids is of pivotal importance for monitoring the development of certain pathologies as well as engineering synthetic replacements. Laser Speckle Rheology (LSR) is a novel optical technology that enables mechanical evaluation of tissue. In LSR, a coherent laser beam illuminates the tissue and temporal speckle intensity fluctuations are analyzed to evaluate mechanical properties. The rate of temporal speckle fluctuations is, however, influenced by both optical and mechanical properties of tissue. Therefore, in this paper, we develop and validate an approach to estimate and compensate for the contributions of light scattering to speckle dynamics and demonstrate the capability of LSR for the accurate extraction of viscoelastic moduli in phantom samples and biological fluids of varying optical and mechanical properties. PMID:23705028

Plasma Profile Measurements for Laser Fusion Research with the Nike KrF Laser

NASA Astrophysics Data System (ADS)

Oh, Jaechul; Weaver, J. L.; Serlin, V.; Obenschain, S. P.

2015-11-01

The grid image refractometer of the Nike laser facility (Nike-GIR) has demonstrated the capability of simultaneously measuring electron density (ne) and temperature (Te) profiles of coronal plasma. For laser plasma instability (LPI) research, the first Nike-GIR experiment successfully measured the plasma profiles in density regions up to ne ~ 4 ×1021 cm-3 (22% of the critical density for 248 nm light of Nike) using an ultraviolet probe laser (λp = 263 nm). The probe laser has been recently replaced with a shorter wavelength laser (λp = 213 nm, a 5th harmonic of the Nd:YAG laser) to diagnose a higher density region. The Nike-GIR system is being further extended to measure plasma profiles in the on-going experiment using 135°-separated Nike beam arrays for the cross-beam energy transfer (CBET) studies. We present an overview of the extended Nike-GIR arrangements and a new numerical algorithm to extract self-consistant plasma profiles with the measured quantities. Work supported by DoE/NNSA.

Guide star lasers for adaptive optics

NASA Astrophysics Data System (ADS)

Roberts, William Thomas, Jr.

Exploitation of the imaging capabilities of the new generation of ground-based astronomical telescopes relies heavily on Adaptive Optics (AO). Current AO system designs call for sodium guide star lasers capable of producing at least eight Watts of power tuned to the peak of the sodium D2 line, with a high duty cycle to avoid saturation, and with 0.5-1.0 GHz spectral broadening. This work comprises development and testing of six candidate laser systems and materials which may afford a path to achieving these goals. An end-pumped CW dye laser producing 4.0 Watts of tuned output power was developed and used to obtain the first accurate measurement of sodium layer scattering efficiency. Methods of optimizing the laser output through improving pump overlap efficiency and reducing the number of intracavity scattering surfaces are covered. The 1181 nm fluorescence peak of Mn5+ ion in Ba5 (PO4)3Cl could be tuned and doubled to reach 589 nm. While efforts to grow this crystal were under way, the Mn5+ ion in natural apatite (Ca5(PO4)3F) was studied as a potential laser material. Fluorescence saturation measurements and transmission saturation are presented, as well as efforts to obtain CW lasing in natural apatite. A Q-switched laser color-center laser in LiF : F-2 was developed and successfully tuned and doubled to the sodium D 2 line. Broad-band lasing of 80 mW and tuned narrow-band lasing of 35 mW at 1178 nm were obtained with 275 mW of input pump power at 1064 nm. The measured thermal properties of this material indicate its potential for scaling to much higher power. A Q-switched intracavity Raman laser was developed in which CaWO 4 was used to shift a Nd:YAG laser, the frequency-doubled output of which was centered at 589.3 nm. To obtain light at 589.0 nm, a compositionally tuned pump laser of Nd : Y3Ga1.1Al3.9O 12 was produced which generated the desired shift, but was inhomogeneous broadened, limiting the tunable power of the material. Finally, temperature tuning of a Nd:YAG laser was demonstrated in which the laser emitted up to 8.6 Watts at a temperature of -21.5 C, bringing the wavelength into a regime favorable for efficient Raman shifting by CaWO4.

Four channel Laser Firing Unit using laser diodes

NASA Technical Reports Server (NTRS)

Rosner, David, Sr.; Spomer, Edwin, Sr.

1994-01-01

This paper describes the accomplishments and status of PS/EDD's (Pacific Scientific/Energy Dynamics Division) internal research and development effort to prototype and demonstrate a practical four channel laser firing unit (LFU) that uses laser diodes to initiate pyrotechnic events. The LFU individually initiates four ordnance devices using the energy from four diode lasers carried over the fiber optics. The LFU demonstrates end-to-end optical built in test (BIT) capabilities. Both Single Fiber Reflective BIT and Dual Fiber Reflective BIT approaches are discussed and reflection loss data is presented. This paper includes detailed discussions of the advantages and disadvantages of both BIT approaches, all-fire and no-fire levels, and BIT detection levels. The following topics are also addressed: electronic control and BIT circuits, fiber optic sizing and distribution, and an electromechanical shutter type safe/arm device. This paper shows the viability of laser diode initiation systems and single fiber BIT for typing military applications.

Construction of a femtosecond laser microsurgery system.

PubMed

Steinmeyer, Joseph D; Gilleland, Cody L; Pardo-Martin, Carlos; Angel, Matthew; Rohde, Christopher B; Scott, Mark A; Yanik, Mehmet Fatih

2010-03-01

Femtosecond laser microsurgery is a powerful method for studying cellular function, neural circuits, neuronal injury and neuronal regeneration because of its capability to selectively ablate sub-micron targets in vitro and in vivo with minimal damage to the surrounding tissue. Here, we present a step-by-step protocol for constructing a femtosecond laser microsurgery setup for use with a widely available compound fluorescence microscope. The protocol begins with the assembly and alignment of beam-conditioning optics at the output of a femtosecond laser. Then a dichroic mount is assembled and installed to direct the laser beam into the objective lens of a standard inverted microscope. Finally, the laser is focused on the image plane of the microscope to allow simultaneous surgery and fluorescence imaging. We illustrate the use of this setup by presenting axotomy in Caenorhabditis elegans as an example. This protocol can be completed in 2 d.

Widely tunable 11 GHz femtosecond fiber laser based on a nonmode-locked source [Widely tunable 11 GHz femtosecond fiber laser based on a non-modelocked source

DOE PAGES

Prantil, Matthew A.; Cormier, Eric; Dawson, Jay W.; ...

2013-08-19

An 11 GHz fiber laser built on a modulated CW platform is described and characterized. This compact, vibrationinsensitive, fiber based system can be operated at wavelengths compatible with high energy fiber technology, is driven by an RF signal directly, and is tunable over a wide range of drive frequencies. The demonstration system when operated at 1040 nm is capable of 50 ns bursts of 575 micro-pulses produced at a macro-pulse rate of 83 kHz where the macro-pulse and micro-pulse energies are 1.8 μJ and 3.2 nJ respectively. Micro-pulse durations of 850 fs are demonstrated. Finally, we discuss extensions to shortermore » duration.« less

Application of laser differential confocal technique in back vertex power measurement for phoropters

NASA Astrophysics Data System (ADS)

Li, Fei; Li, Lin; Ding, Xiang; Liu, Wenli

2012-10-01

A phoropter is one of the most popular ophthalmic instruments used in optometry and the back vertex power (BVP) is one of the most important parameters to evaluate the refraction characteristics of a phoropter. In this paper, a new laser differential confocal vertex-power measurement method which takes advantage of outstanding focusing ability of laser differential confocal (LDC) system is proposed for measuring the BVP of phoropters. A vertex power measurement system is built up. Experimental results are presented and some influence factor is analyzed. It is demonstrated that the method based on LDC technique has higher measurement precision and stronger environmental anti-interference capability compared to existing methods. Theoretical analysis and experimental results indicate that the measurement error of the method is about 0.02m-1.

Development of a fiber-guided laser ultrasonic system resilient to high temperature and gamma radiation for nuclear power plant pipe monitoring

NASA Astrophysics Data System (ADS)

Yang, Jinyeol; Lee, Hyeonseok; Lim, Hyung Jin; Kim, Nakhyeon; Yeo, Hwasoo; Sohn, Hoon

2013-08-01

This study develops an embeddable optical fiber-guided laser ultrasonic system for structural health monitoring (SHM) of pipelines exposed to high temperature and gamma radiation inside nuclear power plants (NPPs). Recently, noncontact laser ultrasonics is gaining popularity among the SHM community because of its advantageous characteristics such as (a) scanning capability, (b) immunity against electromagnetic interference (EMI) and (c) applicability to high-temperature surfaces. However, its application to NPP pipelines has been hampered because pipes inside NPPs are often covered by insulators and/or target surfaces are not easily accessible. To overcome this problem, this study designs embeddable optical fibers and fixtures so that laser beams used for ultrasonic inspection can be transmitted between the laser sources and the target pipe. For guided-wave generation, an Nd:Yag pulsed laser coupled with an optical fiber is used. A high-power pulsed laser beam is guided through the optical fiber onto a target structure. Based on the principle of laser interferometry, the corresponding response is measured using a different type of laser beam guided by another optical fiber. All devices are especially designed to sustain high temperature and gamma radiation. The robustness/resilience of the proposed measurement system installed on a stainless steel pipe specimen has been experimentally verified by exposing the specimen to high temperature of up to 350 °C and optical fibers to gamma radiation of up to 125 kGy (20 kGy h-1).

Laser microprocessing and nanoengineering of large-area functional micro/nanostructures

NASA Astrophysics Data System (ADS)

Tang, M.; Xie, X. Z.; Yang, J.; Chen, Z. C.; Xu, L.; Choo, Y. S.; Hong, M. H.

2011-12-01

Laser microprocessing and nanoengineering are of great interest to both scientists and engineers, since the inspired properties of functional micro/nanostructures over large areas can lead to numerous unique applications. Currently laser processing systems combined with high speed automation ensure the focused laser beam to process various materials at a high throughput and a high accuracy over large working areas. UV lasers are widely used in both laser microprocessing and nanoengineering. However by improving the processing methods, green pulsed laser is capable of replacing UV lasers to make high aspect ratio micro-grooves on fragile and transparent sapphire substrates. Laser micro-texturing can also tune the wetting property of metal surfaces from hydrophilic to super-hydrophobic at a contact angle of 161° without chemical coating. Laser microlens array (MLA) can split a laser beam into multiple laser beams and reduce the laser spot size down to sub-microns. It can be applied to fabricate split ring resonator (SRR) meta-materials for THz sensing, surface plasmonic resonance (SPR) structures for NIR and molding tools for soft lithography. Furthermore, laser interference lithography combined with thermal annealing can obtain a large area of sub-50nm nano-dot clusters used for SPR applications.

Monitoring spacecraft atmosphere contaminants by laser absorption spectroscopy

NASA Technical Reports Server (NTRS)

Steinfeld, J. I.

1976-01-01

Laser-based spectrophotometric methods which have been proposed for the detection of trace concentrations of gaseous contaminants include Raman backscattering (LIDAR) and passive radiometry (LOPAIR). Remote sensing techniques using laser spectrometry are presented and in particular a simple long-path laser absorption method (LOLA), which is capable of resolving complex mixtures of closely related trace contaminants at ppm levels is discussed. A number of species were selected for study which are representative of those most likely to accumulate in closed environments, such as submarines or long-duration manned space flights. Computer programs were developed which will permit a real-time analysis of the monitored atmosphere. Estimates of the dynamic range of this monitoring technique for various system configurations, and comparison with other methods of analysis, are given.

Optical Instruments

NASA Technical Reports Server (NTRS)

1990-01-01

Precision Lapping and Optical Co. has developed a wide variety of hollow retroreflector systems for applications involving the entire optical spectrum; they are, according to company literature, cheaper, more accurate, lighter and capable of greater size than solid prisms. Precision Lapping's major customers are aerospace and defense companies, government organizations, R&D and commercial instrument companies. For example, Precision Lapping supplies hollow retroreflectors for the laser fire control system of the Army's Abrams tank, and retroreflectors have been and are being used in a number of space tests relative to the Air Force's Strategic Defense Initiative research program. An example of a customer/user is Chesapeake Laser Systems, producer of the Laser Tracker System CMS-2000, which has applications in SDI research and industrial robotics. Another customer is MDA Scientific, Inc., manufacturer of a line of toxic gas detection systems used to monitor hazardous gases present in oil fields, refineries, offshore platforms, chemical plants, waste storage sites and other locations where gases are released into the environment.

On the feasibility of tomographic-PIV with low pulse energy illumination in a lifted turbulent jet flame

NASA Astrophysics Data System (ADS)

Boxx, I.; Carter, C. D.; Meier, W.

2014-08-01

Tomographic particle image velocimetry (tomographic-PIV) is a recently developed measurement technique used to acquire volumetric velocity field data in liquid and gaseous flows. The technique relies on line-of-sight reconstruction of the rays between a 3D particle distribution and a multi-camera imaging system. In a turbulent flame, however, index-of-refraction variations resulting from local heat-release may inhibit reconstruction and thereby render the technique infeasible. The objective of this study was to test the efficacy of tomographic-PIV in a turbulent flame. An additional goal was to determine the feasibility of acquiring usable tomographic-PIV measurements in a turbulent flame at multi-kHz acquisition rates with current-generation laser and camera technology. To this end, a setup consisting of four complementary metal oxide semiconductor cameras and a dual-cavity Nd:YAG laser was implemented to test the technique in a lifted turbulent jet flame. While the cameras were capable of kHz-rate image acquisition, the laser operated at a pulse repetition rate of only 10 Hz. However, use of this laser allowed exploration of the required pulse energy and thus power for a kHz-rate system. The imaged region was 29 × 28 × 2.7 mm in size. The tomographic reconstruction of the 3D particle distributions was accomplished using the multiplicative algebraic reconstruction technique. The results indicate that volumetric velocimetry via tomographic-PIV is feasible with pulse energies of 25 mJ, which is within the capability of current-generation kHz-rate diode-pumped solid-state lasers.

Toward the realization of a compact chemical sensor platform using quantum cascade lasers

NASA Astrophysics Data System (ADS)

Holthoff, Ellen L.; Marcus, Logan S.; Pellegrino, Paul M.

2015-05-01

The Army is investigating several spectroscopic techniques (e.g., infrared spectroscopy) that could allow for an adaptable sensor platform. Traditionally, chemical sensing platforms have been hampered by the opposing concerns of increasing sensor capability while maintaining a minimal package size. Current sensors, although reasonably sized, are geared to more classical chemical threats, and the ability to expand their capabilities to a broader range of emerging threats is uncertain. Recently, photoacoustic spectroscopy, employed in a sensor format, has shown enormous potential to address these ever-changing threats, while maintaining a compact sensor design. In order to realize the advantage of photoacoustic sensor miniaturization, light sources of comparable size are required. Recent research has employed quantum cascade lasers (QCLs) in combination with MEMS-scale photoacoustic cell designs. The continuous tuning capability of QCLs over a broad wavelength range in the mid-infrared spectral region greatly expands the number of compounds that can be identified. Results have demonstrated that utilizing a tunable QCL with a MEMS-scale photoacoustic cell produces favorable detection limits (ppb levels) for chemical targets (e.g., dimethyl methyl phosphonate (DMMP), vinyl acetate, 1,4-dioxane). Although our chemical sensing research has benefitted from the broad tuning capabilities of QCLs, the limitations of these sources must be considered. Current commercially available tunable systems are still expensive and obviously geared more toward laboratory operation, not fielding. Although the laser element itself is quite small, the packaging, power supply, and controller remain logistical burdens. Additionally, operational features such as continuous wave (CW) modulation and laser output powers while maintaining wide tunability are not yet ideal for a variety of sensing applications. In this paper, we will discuss our continuing evaluation of QCL technology as it matures in relation to our ultimate goal of a universal compact chemical sensor platform.

Initial conceptual design study of self-critical nuclear pumped laser systems

NASA Technical Reports Server (NTRS)

Rodgers, R. J.

1979-01-01

An analytical study of self-critical nuclear pumped laser system concepts was performed. Primary emphasis was placed on reactor concepts employing gaseous uranium hexafluoride (UF6) as the fissionable material. Relationships were developed between the key reactor design parameters including reactor power level, critical mass, neutron flux level, reactor size, operating pressure, and UF6 optical properties. The results were used to select a reference conceptual laser system configuration. In the reference configuration, the 3.2 m cubed lasing volume is surrounded by a graphite internal moderator and a region of heavy water. Results of neutronics calculations yield a critical mass of 4.9 U(235) in the form (235)UF6. The configuration appears capable of operating in a continuous steady-state mode. The average gas temperature in the core is 600 K and the UF6 partial pressure within the lasing volume is 0.34 atm.

Multispecies absorption spectroscopy of detonation events at 100  kHz using a fiber-coupled, time-division-multiplexed quantum-cascade-laser system.

PubMed

Rein, Keith D; Roy, Sukesh; Sanders, Scott T; Caswell, Andrew W; Schauer, Frederick R; Gord, James R

2016-08-10

A mid-infrared fiber-coupled laser system constructed around three time-division-multiplexed quantum-cascade lasers capable of measuring the absorption spectra of CO, CO₂, and N₂O at 100 kHz over a wide range of operating pressures and temperatures is demonstrated. This system is first demonstrated in a laboratory burner and then used to measure temperature, pressure, and concentrations of CO, CO₂, and N₂O as a function of time in a detonated mixture of N₂O and C₃H₈. Both fuel-rich and fuel-lean detonation cases are outlined. High-temperature fluctuations during the blowdown are observed. Concentrations of CO are shown to decrease with time for fuel-lean conditions and increase for fuel-rich conditions.

Preliminary study on detection sediment contamination in soil affected by the Indian Ocean giant tsunami 2004 in Aceh, Indonesia using laser-induced breakdown spectroscopy (LIBS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Idris, Nasrullah, E-mail: nasrullah.idris@unsyiah.ac.id; Ramli, Muliadi; Hedwig, Rinda

This work is intended to asses the capability of LIBS for the detection of the tsunami sediment contamination in soil. LIBS apparatus used in this work consist of a laser system and an optical multichannel analyzer (OMA) system. The soil sample was collected from in Banda Aceh City, Aceh, Indonesia, the most affected region by the giant Indian Ocean tsunami 2004. The laser beam was focused onto surface of the soil pellet using a focusing lens to produce luminous plasma. The experiment was conducted under air as surrounding gas at 1 atmosphere. The emission spectral lines from the plasma weremore » detected by the OMA system. It was found that metal including heavy metals can surely be detected, thus implying the potent of LIBS technique as a fast screening tools of tsunami sediment contamination.« less

Fast synchronized dual-wavelength laser speckle imaging system for monitoring hemodynamic changes in a stroke mouse model

PubMed Central

Qin, Jia; Shi, Lei; Dziennis, Suzan; Reif, Roberto; Wang, Ruikang K.

2014-01-01

In this paper, we describe a newly developed synchronized dual-wavelength laser speckle contrast imaging (SDW-LSCI) system, which contains two cameras that are synchronously triggered to acquire data. The system can acquire data at a high spatiotemporal resolution (up to 500Hz for ~1000×1000 pixels). A mouse model of stroke is used to demonstrate the capability for imaging the fast changes (within tens of milliseconds) in oxygenated and deoxygenated hemoglobin concentration, and the relative changes in blood flow in the mouse brain, through an intact cranium. This novel imaging technology will enable the study of fast hemodynamics and metabolic changes in vascular diseases. PMID:23027260

Demonstration of a rapidly-swept external cavity quantum cascade laser for rapid and sensitive quantification of chemical mixtures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.

2016-02-13

A rapidly-swept external cavity quantum cascade laser (ECQCL) system for fast open-path quantification of multiple chemicals and mixtures is presented. The ECQCL system is swept over its entire tuning range (>100 cm-1) at frequencies up to 200 Hz. At 200 Hz the wavelength tuning rate and spectral resolution are 2x104 cm-1/sec and < 0.2 cm-1, respectively. The capability of the current system to quantify changes in chemical concentrations on millesecond timescales is demonstrated at atmospheric pressure using an open-path multi-pass cell. The detection limits for chemicals ranged from ppb to ppm levels depending on the absorption cross-section.

Mimicking subsecond neurotransmitter dynamics with femtosecond laser stimulated nanosystems.

PubMed

Nakano, Takashi; Chin, Catherine; Myint, David Mo Aung; Tan, Eng Wui; Hale, Peter John; Krishna M, Bala Murali; Reynolds, John N J; Wickens, Jeff; Dani, Keshav M

2014-06-23

Existing nanoscale chemical delivery systems target diseased cells over long, sustained periods of time, typically through one-time, destructive triggering. Future directions lie in the development of fast and robust techniques capable of reproducing the pulsatile chemical activity of living organisms, thereby allowing us to mimic biofunctionality. Here, we demonstrate that by applying programmed femtosecond laser pulses to robust, nanoscale liposome structures containing dopamine, we achieve sub-second, controlled release of dopamine--a key neurotransmitter of the central nervous system--thereby replicating its release profile in the brain. The fast delivery system provides a powerful new interface with neural circuits, and to the larger range of biological functions that operate on this short timescale.

Annual Industrial Capabilities Report to Congress

DTIC Science & Technology

1999-02-01

suspension systems is not a concern. Deformable Mirrors (September 1998) The atmosphere, temperature variations, and vibration distort optical system...images. Deformable mirrors can compensate for these effects in real time. They are used in surveillance optics, laser weapons, and astronomical telescopes...This assessment investigated the availability of current and potential deformable mirror producers, and possible alternative technologies. The

DE-STARLITE: A directed energy planetary defense mission

NASA Astrophysics Data System (ADS)

Kosmo, Kelly; Pryor, Mark; Lubin, Philip; Hughes, Gary B.; O'Neill, Hugh; Meinhold, Peter; Suen, Jonathan; Riley, Jordan; Griswold, Janelle; Cook, Brianna V.; Johansson, Isabella E.; Zhang, Qicheng; Walsh, Kevin; Melis, Carl; Kangas, Miikka; Bible, Johanna; Motta, Caio; Brashears, Travis; Mathew, Shana; Bollag, Justin

2014-09-01

This paper presents the motivation behind and design of a directed energy planetary defense system that utilizes laser ablation of an asteroid to impart a deflecting force on the target. The proposed system is called DE-STARLITE for Directed Energy System for Targeting of Asteroids and ExploRation - LITE as it is a small, stand-on unit of a larger standoff DE-STAR system. Pursuant to the stand-on design, ion engines will propel the spacecraft from low-Earth orbit (LEO) to the near-Earth asteroid (NEA). During laser ablation, the asteroid itself becomes the "propellant"; thus a very modest spacecraft can deflect an asteroid much larger than would be possible with a system of similar mission mass using ion beam deflection (IBD) or a gravity tractor. DE-STARLITE is capable of deflecting an Apophis-class (325 m diameter) asteroid with a 15-year targeting time. The mission fits within the rough mission parameters of the Asteroid Redirect Mission (ARM) program in terms of mass and size and has much greater capability for planetary defense than current proposals and is readily scalable to the threat. It can deflect all known threats with sufficient warning.

Antares Alignment Gimbal Positioner

NASA Astrophysics Data System (ADS)

Day, R. D.; Viswanathan, V. K.; Saxman, A. C.; Lujan, R. E.; Woodfin, G. L.; Sweatt, W. C.

1981-12-01

Antares is a 24-beam 40-TW carbon-dioxide (CO2) laser fusion system currently under construction at the Los Alamos National Laboratory. The Antares alignment gimbal positioner (AGP) is an optomechanical instrument that will be used for target alignment and alignment of the 24 laser beams, as well as beam quality assessments. The AGP will be capable of providing pointing, focusing, and wavefront optical path difference, as well as aberration information at both helium-neon (He-Ne) and CO2 wavelengths. It is designed to allow the laser beams to be aligned to any position within a 1-cm cube to a tolerance of 10 μm.

Self-aligned spatial filtering using laser optical tweezers.

PubMed

Birkbeck, Aaron L; Zlatanovic, Sanja; Esener, Sadik C

2006-09-01

We present an optical spatial filtering device that has been integrated into a microfluidic system and whose motion and alignment is controlled using a laser optical tweezer. The lithographically patterned micro-optical spatial filter device filters out higher frequency additive noise components by automatically aligning itself in three dimensions to the focus of the laser beam. This self-alignment capability is achieved through the attachment of a refractive optical element directly over the circular aperture or pinhole of the spatial filter. A discussion of two different spatial filter designs is presented along with experimental results that demonstrate the effectiveness of the self-aligned micro-optic spatial filter.

Status of Multi-beam Long Trace-profiler Development

NASA Technical Reports Server (NTRS)

Gubarev, Mikhail V.; Merthe, Daniel J.; Kilaru, Kiranmayee; Kester, Thomas; Ramsey, Brian; McKinney, Wayne R.; Takacs, Peter Z.; Dahir, A.; Yashchuk, Valeriy V.

2013-01-01

The multi-beam long trace profiler (MB-LTP) is under development at NASA's Marshall Space Flight Center. The traditional LTPs scans the surface under the test by a single laser beam directly measuring the surface figure slope errors. While capable of exceptional surface slope accuracy, the LTP single beam scanning has slow measuring speed. Metrology efficiency can be increased by replacing the single laser beam with multiple beams that can scan a section of the test surface at a single instance. The increase in speed with such a system would be almost proportional to the number of laser beams. The progress for a multi-beam long trace profiler development is presented.

Pulsed laser triggered high speed microfluidic switch

NASA Astrophysics Data System (ADS)

Wu, Ting-Hsiang; Gao, Lanyu; Chen, Yue; Wei, Kenneth; Chiou, Pei-Yu

2008-10-01

We report a high-speed microfluidic switch capable of achieving a switching time of 10 μs. The switching mechanism is realized by exciting dynamic vapor bubbles with focused laser pulses in a microfluidic polydimethylsiloxane (PDMS) channel. The bubble expansion deforms the elastic PDMS channel wall and squeezes the adjacent sample channel to control its fluid and particle flows as captured by the time-resolved imaging system. A switching of polystyrene microspheres in a Y-shaped channel has also been demonstrated. This ultrafast laser triggered switching mechanism has the potential to advance the sorting speed of state-of-the-art microscale fluorescence activated cell sorting devices.

Reinjection laser oscillator and method

DOEpatents

McLellan, Edward J.

1984-01-01

A uv preionized CO.sub.2 oscillator with integral four-pass amplifier capable of providing 1 to 5 GW laser pulses with pulse widths from 0.1 to 0.5 ns full width at half-maximum (FWHM) is described. The apparatus is operated at any pressure from 1 atm to 10 atm without the necessity of complex high voltage electronics. The reinjection technique employed gives rise to a compact, efficient system that is particularly immune to alignment instabilities with a minimal amount of hardware and complexity.

The Laser Communications Relay and the Path to the Next Generation Near Earth Relay

NASA Technical Reports Server (NTRS)

Israel, David J.

2015-01-01

NASA Goddard Space Flight Center is currently developing the Laser Communications Relay Demonstration (LCRD) as a Path to the Next Generation Near Earth Space Communication Network. The current NASA Space Network or Tracking and Data Relay Satellite System is comprised of a constellation of Tracking and Data Relay Satellites (TDRS) in geosynchronous orbit and associated ground stations and operation centers. NASA is currently targeting a next generation of relay capability on orbit in the 2025 timeframe.

Wide-field airborne laser diode array illuminator: demonstration results

NASA Astrophysics Data System (ADS)

Suiter, H. R.; Holloway, J. H., Jr.; Tinsley, K. R.; Pham, C. N.; Kloess, E. C., III; Witherspoon, N. H.; Stetson, S.; Crosby, F.; Nevis, A.; McCarley, K. A.; Seales, T. C.

2005-06-01

The Airborne Littoral Reconnaissance Technology (ALRT) program has successfully demonstrated the Wide-Field Airborne Laser Diode Array Illuminator (ALDAI-W). This illuminator is designed to illuminate a large area from the air with limited power, weight, and volume. A detection system, of which the ALDAI-W is a central portion, is capable of detecting surface-laid minefields in absolute darkness, extending the allowed mission times to night operations. This will be an overview report, giving processing results and suggested paths for additional development.

Ultra-narrow band diode lasers with arbitrary pulse shape modulation (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ryasnyanskiy, Aleksandr I.; Smirnov, Vadim; Mokhun, Oleksiy; Glebov, Alexei L.; Glebov, Leon B.

2017-03-01

Wideband emission spectra of laser diode bars (several nanometers) can be largely narrowed by the usage of thick volume Bragg gratings (VBGs) recorded in photo-thermo-refractive glass. Such narrowband systems, with GHz-wide emission spectra, found broad applications for Diode Pumped Alkali vapor Lasers, optically pumped rare gas metastable lasers, Spin Exchange Optical Pumping, atom cooling, etc. Although the majority of current applications of narrow line diode lasers require CW operation, there are a variety of fields where operation in a different pulse mode regime is necessary. Commercial electric pulse generators can provide arbitrary current pulse profiles (sinusoidal, rectangular, triangular and their combinations). The pulse duration and repetition rate however, have an influence on the laser diode temperature, and therefore, the emitting wavelength. Thus, a detailed analysis is needed to understand the correspondence between the optical pulse profiles from a diode laser and the current pulse profiles; how the pulse profile and duty cycle affects the laser performance (e.g. the wavelength stability, signal to noise ratio, power stability etc.). We present the results of detailed studies of the narrowband laser diode performance operating in different temporal regimes with arbitrary pulse profiles. The developed narrowband (16 pm) tunable laser systems at 795 nm are capable of operating in different pulse regimes while keeping the linewidth, wavelength, and signal-to-noise ratio (>20 dB) similar to the corresponding CW modules.

Laser beam alignment and profilometry using diagnostic fluorescent safety mirrors

NASA Astrophysics Data System (ADS)

Lizotte, Todd E.

2011-03-01

There are a wide range of laser beam delivery systems in use for various purposes; including industrial and medical applications. Virtually all such beam delivery systems for practical purposes employ optical systems comprised of mirrors and lenses to shape, focus and guide the laser beam down to the material being processed. The goal of the laser beam delivery is to set the optimum parameters and to "fold" the beam path to reduce the mechanical length of the optical system, thereby allowing a physically compact system. In many cases, even a compact system can incorporate upwards of six mirrors and a comparable number of lenses all needing alignment so they are collinear. One of the major requirements for use of such systems in industry is a method of safe alignment. The alignment process requires that the aligner determine where the beam strikes each element. The aligner should also preferably be able to determine the shape or pattern of the laser beam at that point and its relative power. These alignments are further compounded in that the laser beams generated are not visible to the unaided human eye. Such beams are also often of relatively high power levels, and are thereby a significant hazard to the eyes of the aligner. Obvious an invisible beam makes it nearly impossible to align laser system without some form of optical assistance. The predominant method of visually aligning the laser beam delivery is the use of thermal paper, paper cards or fluorescing card material. The use of paper products which have limited power handling capability or coated plastics can produce significant debris and contaminants within the beam line that ultimately damage the optics. The use of the cards can also create significant laser light scatter jeopardizing the safety of the person aligning the system. This paper covers a new safety mirror design for use with at various UV and Near IR wavelengths (193 nm to 1064 nm) within laser beam delivery systems and how its use can provide benefits covering eye safety, precise alignment and beam diagnostics.

Laser Threat Analysis System (LTAS)

NASA Astrophysics Data System (ADS)

Pfaltz, John M.; Richardson, Christina E.; Ruiz, Abel; Barsalou, Norman; Thomas, Robert J.

2002-11-01

LTAS is a totally integrated modeling and simulation environment designed for the purpose of ascertaining the susceptibility of Air Force pilots and air crews to optical radiation threats. Using LTAS, mission planners can assess the operational impact of optically directed energy weapons and countermeasures. Through various scenarios, threat analysts are able to determine the capability of laser threats and their impact on operational missions including the air crew's ability to complete their mission effectively. Additionally, LTAS allows the risk of laser use on training ranges and the requirement for laser protection to be evaluated. LTAS gives mission planners and threat analysts complete control of the threat environment including threat parameter control and placement, terrain mapping (line-of-site), atmospheric conditions, and laser eye protection (LEP) selection. This report summarizes the design of the final version of LTAS, and the modeling methodologies implemented to accomplish analysis.

Vision requirements for Space Station applications

NASA Technical Reports Server (NTRS)

Crouse, K. R.

1985-01-01

Problems which will be encountered by computer vision systems in Space Station operations are discussed, along with solutions be examined at Johnson Space Station. Lighting cannot be controlled in space, nor can the random presence of reflective surfaces. Task-oriented capabilities are to include docking to moving objects, identification of unexpected objects during autonomous flights to different orbits, and diagnoses of damage and repair requirements for autonomous Space Station inspection robots. The approaches being examined to provide these and other capabilities are television IR sensors, advanced pattern recognition programs feeding on data from laser probes, laser radar for robot eyesight and arrays of SMART sensors for automated location and tracking of target objects. Attention is also being given to liquid crystal light valves for optical processing of images for comparisons with on-board electronic libraries of images.

High average power diode pumped solid state laser

NASA Astrophysics Data System (ADS)

Gao, Yue; Wang, Yanjie; Chan, Amy; Dawson, Murray; Greene, Ben

2017-03-01

A new generation of high average power pulsed multi-joule solid state laser system has been developed at EOS Space Systems for various space related tracking applications. It is a completely diode pumped, fully automated multi-stage system consisting of a pulsed single longitudinal mode oscillator, three stages of pre-amplifiers, two stages of power amplifiers, completely sealed phase conjugate mirror or stimulated Brillouin scattering (SBS) cell and imaging relay optics with spatial filters in vacuum cells. It is capable of generating pulse energy up to 4.7 J, a beam quality M 2 ~ 3, pulse width between 10-20 ns, and a pulse repetition rate between 100-200 Hz. The system has been in service for more than two years with excellent performance and reliability.

High-throughput optofluidic system for the laser microsurgery of oocytes

NASA Astrophysics Data System (ADS)

Chandsawangbhuwana, Charlie; Shi, Linda Z.; Zhu, Qingyuan; Alliegro, Mark C.; Berns, Michael W.

2012-01-01

This study combines microfluidics with optical microablation in a microscopy system that allows for high-throughput manipulation of oocytes, automated media exchange, and long-term oocyte observation. The microfluidic component of the system transports oocytes from an inlet port into multiple flow channels. Within each channel, oocytes are confined against a microfluidic barrier using a steady fluid flow provided by an external computer-controlled syringe pump. This allows for easy media replacement without disturbing the oocyte location. The microfluidic and optical-laser microbeam ablation capabilities of the system were validated using surf clam (Spisula solidissima) oocytes that were immobilized in order to permit ablation of the 5 μm diameter nucleolinus within the oocyte nucleolus. Oocytes were the followed and assayed for polar body ejection.

A new approach to driving and controlling precision lasers for cold-atom science

NASA Astrophysics Data System (ADS)

Luey, Ben; Shugrue, Jeremy; Anderson, Mike

2014-05-01

Vescent's Integrated Control Electronics (ICE) Platform is a new approach to controlling and driving lasers and other electoral devices in complex atomic and optical experiments. By employing low-noise, high-bandwidth analog electronics with digital control, ICE combines the performance of analog design with the convenience of the digital world. Utilizing a simple USB COM port interface, ICE can easily be controlled via LabView, Python, or an FPGA. High-speed TTL inputs enable precise external timing or triggering. ICE is capable of generating complex timing internally, enabling ICE to drive an entire experiment or it can be directed by an external control program. The system is capable of controlling up to 8 unique ICE slave boards providing flexibility to tailor an assortment of electronics hardware to the needs of a specific experiment. Examples of ICE slave boards are: a current controller and peak-lock laser servo, a four channel temperature controller, a current controller and offset phase lock servo. A single ensemble can drive, stabilize, and frequency lock 3 lasers in addition to powering an optical amplifier, while still leaving 2 remaining slots for further control needs. Staff Scientist

Perspective on One Decade of Laser Propulsion Research at Air Force Research Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larson, C. William

The Air Force Laser Propulsion Program spanned nearly 10-years and included about 35-weeks of experimental research with the Pulsed Laser Vulnerability Test System of the High Energy Laser Systems Test Facility at White Sands Missile Range, New Mexico, WSMR/HELSTF/PLVTS. PLVTS is a pulsed CO2 laser that produces up to 10 kW of power in {approx}10 cm{sup 2} spot at wavelength of 10.6 microns. The laser is capable of a pulse repetition rate up to 25 Hz, with pulse durations of about 20 microseconds. During the program basic research was conducted on the production of propulsion thrust from laser energy throughmore » heating of air and ablation of various candidate rocket propellant fuels. Flight tests with an ablation fuel (Delrin) and air were accomplished with a model Laser Lightcraft vehicle that was optimized for propulsion by the PLVTS at its maximum power output, 10 kW at 25 Hz, 400 J/pulse. Altitudes exceeding 200-feet were achieved with ablation fuels. The most recent contributions to the technology included development of a mini-thruster standard for testing of chemically enhanced fuels and theoretical calculations on the performance of formulations containing ammonium nitrate and Delrin. Results of these calculations will also be reported here.« less

Perspective on One Decade of Laser Propulsion Research at Air Force Research Laboratory

NASA Astrophysics Data System (ADS)

Larson, C. William

2008-04-01

The Air Force Laser Propulsion Program spanned nearly 10-years and included about 35-weeks of experimental research with the Pulsed Laser Vulnerability Test System of the High Energy Laser Systems Test Facility at White Sands Missile Range, New Mexico, WSMR/HELSTF/PLVTS. PLVTS is a pulsed CO2 laser that produces up to 10 kW of power in ˜10 cm2 spot at wavelength of 10.6 microns. The laser is capable of a pulse repetition rate up to 25 Hz, with pulse durations of about 20 microseconds. During the program basic research was conducted on the production of propulsion thrust from laser energy through heating of air and ablation of various candidate rocket propellant fuels. Flight tests with an ablation fuel (Delrin) and air were accomplished with a model Laser Lightcraft vehicle that was optimized for propulsion by the PLVTS at its maximum power output, 10 kW at 25 Hz, 400 J/pulse. Altitudes exceeding 200-feet were achieved with ablation fuels. The most recent contributions to the technology included development of a mini-thruster standard for testing of chemically enhanced fuels and theoretical calculations on the performance of formulations containing ammonium nitrate and Delrin. Results of these calculations will also be reported here.

Non-optically combined multispectral source for IR, visible, and laser testing

NASA Astrophysics Data System (ADS)

Laveigne, Joe; Rich, Brian; McHugh, Steve; Chua, Peter

2010-04-01

Electro Optical technology continues to advance, incorporating developments in infrared and laser technology into smaller, more tightly-integrated systems that can see and discriminate military targets at ever-increasing distances. New systems incorporate laser illumination and ranging with gated sensors that allow unparalleled vision at a distance. These new capabilities augment existing all-weather performance in the mid-wave infrared (MWIR) and long-wave infrared (LWIR), as well as low light level visible and near infrared (VNIR), giving the user multiple means of looking at targets of interest. There is a need in the test industry to generate imagery in the relevant spectral bands, and to provide temporal stimulus for testing range-gated systems. Santa Barbara Infrared (SBIR) has developed a new means of combining a uniform infrared source with uniform laser and visible sources for electro-optics (EO) testing. The source has been designed to allow laboratory testing of surveillance systems incorporating an infrared imager and a range-gated camera; and for field testing of emerging multi-spectral/fused sensor systems. A description of the source will be presented along with performance data relating to EO testing, including output in pertinent spectral bands, stability and resolution.

Laser Communication Experiments with Artemis Satellite

NASA Astrophysics Data System (ADS)

Kuzkov, Sergii; Sodnik, Zoran; Kuzkov, Volodymyr

2013-10-01

In November 2001, the European Space Agency (ESA) established the world-first inter-satellite laser communication link between the geostationary ARTEMIS satellite and the low Earth orbiting (LEO) SPOT-4 Earth observation satellite, demonstrating data rates of 50 Mbps. In 2006, the Japanese Space Agency launched the KIRARI (OICETS) LEO satellite with a compatible laser communication terminal and bidirectional laser communication links (50 Mbps and 2 Mbps) were successfully realized between KIRARI and ARTEMIS. ESA is now developing the European Data Relay Satellite (EDRS) system, which will use laser communication technology to transmit data between the Sentinel 1 and 2 satellites in LEO to two geostationary satellites (EDRS-A and EDRS-C) at data rates of 1.8 Gbps. As the data handling capabilities of state-of-the-art telecommunication satellites in GEO increase so is the demand for the feeder-link bandwidth to be transmitted from ground. This is why there is an increasing interest in developing high bandwidth ground-to-space laser communication systems working through atmosphere. In 2002, the Main Astronomical Observatory (MAO) started the development of its own laser communication system for its 0.7m AZT-2 telescope, located in Kyiv, Ukraine. The work was supported by the National Space Agency of Ukraine and by ESA. MAO developed a highly accurate computerized tracking system for AZT-2 telescope and a compact laser communication package called LACES (Laser Atmosphere and Communication Experiments with Satellites). The LACES instrument includes a camera of the pointing and tracking subsystems, a receiver module, a laser transmitter module, a tip/tilt atmospheric turbulence compensation subsystem, a bit error rate tester module and other optical and electronic components. The principal subsystems are mounted on a platform, which is located at the Cassegrain focus of the AZT-2 telescope. All systems were tested with the laser communication payload on-board ARTEMIS and the data analysis was supported by the telemetry received from the ARTEMIS payload control centre in Redu (Belgium). Special attention was focused on the investigation of the impact of atmosphere turbulence on laser beam propagation, especially in cloudy conditions. A description of our telescope and ground based laser system as well as the experimental results will be presented.

Configuration of electro-optic fire source detection system

NASA Astrophysics Data System (ADS)

Fabian, Ram Z.; Steiner, Zeev; Hofman, Nir

2007-04-01

The recent fighting activities in various parts of the world have highlighted the need for accurate fire source detection on one hand and fast "sensor to shooter cycle" capabilities on the other. Both needs can be met by the SPOTLITE system which dramatically enhances the capability to rapidly engage hostile fire source with a minimum of casualties to friendly force and to innocent bystanders. Modular system design enable to meet each customer specific requirements and enable excellent future growth and upgrade potential. The design and built of a fire source detection system is governed by sets of requirements issued by the operators. This can be translated into the following design criteria: I) Long range, fast and accurate fire source detection capability. II) Different threat detection and classification capability. III) Threat investigation capability. IV) Fire source data distribution capability (Location, direction, video image, voice). V) Men portability. ) In order to meet these design criteria, an optimized concept was presented and exercised for the SPOTLITE system. Three major modular components were defined: I) Electro Optical Unit -Including FLIR camera, CCD camera, Laser Range Finder and Marker II) Electronic Unit -including system computer and electronic. III) Controller Station Unit - Including the HMI of the system. This article discusses the system's components definition and optimization processes, and also show how SPOTLITE designers successfully managed to introduce excellent solutions for other system parameters.

Laser induced breakdown spectroscopy (LIBS) as a rapid tool for material analysis

NASA Astrophysics Data System (ADS)

Hussain, T.; Gondal, M. A.

2013-06-01

Laser induced breakdown spectroscopy (LIBS) is a novel technique for elemental analysis based on laser-generated plasma. In this technique, laser pulses are applied for ablation of the sample, resulting in the vaporization and ionization of sample in hot plasma which is finally analyzed by the spectrometer. The elements are identified by their unique spectral signatures. LIBS system was developed for elemental analysis of solid and liquid samples. The developed system was applied for qualitative as well as quantitative measurement of elemental concentration present in iron slag and open pit ore samples. The plasma was generated by focusing a pulsed Nd:YAG laser at 1064 nm on test samples to study the capabilities of LIBS as a rapid tool for material analysis. The concentrations of various elements of environmental significance such as cadmium, calcium, magnesium, chromium, manganese, titanium, barium, phosphorus, copper, iron, zinc etc., in these samples were determined. Optimal experimental conditions were evaluated for improving the sensitivity of developed LIBS system through parametric dependence study. The laser-induced breakdown spectroscopy (LIBS) results were compared with the results obtained using standard analytical technique such as inductively couple plasma emission spectroscopy (ICP). Limit of detection (LOD) of our LIBS system were also estimated for the above mentioned elements. This study demonstrates that LIBS could be highly appropriate for rapid online analysis of iron slag and open pit waste.

Standard measurement procedures for the characterization of fs-laser optical components

NASA Astrophysics Data System (ADS)

Starke, Kai; Ristau, Detlev; Welling, Herbert

2003-05-01

Ultra-short pulse laser systems are considered as promising tools in the fields of precise micro-machining and medicine applications. In the course of the development of reliable table top laser systems, a rapid growth of ultra-short pulse applications could be observed during the recent years. The key for improving the performance of high power laser systems is the quality of the optical components concerning spectral characteristics, optical losses and the power handling capability. In the field of ultra-short pulses, standard measurement procedures in quality management have to be validated in respect to effects induced by the extremely high peak power densities. The present work, which is embedded in the EUREKA-project CHOCLAB II, is predominantly concentrated on measuring the multiple-pulse LIDT (ISO 11254-2) in the fs-regime. A measurement facility based on a Ti:Sapphire-CPA system was developed to investigate the damage behavior of optical components. The set-up was supplied with an improved pulse energy detector discriminating the influence of pulse-to-pulse energy fluctuations on the incidence of damage. Aditionally, a laser-calorimetric measurement facility determining the absorption (ISO 11551) utilizing a fs-Ti:Sapphire laser was accomplished. The investigation for different pulse durations between 130 fs and 1 ps revealed a drastic increase of absorption in titania coatings for ultra-short pulses.

Down-bore two-laser heterodyne velocimetry of an implosion-driven hypervelocity launcher

NASA Astrophysics Data System (ADS)

Hildebrand, Myles; Huneault, Justin; Loiseau, Jason; Higgins, Andrew J.

2017-01-01

The implosion-driven launcher uses explosives to shock-compress helium, driving well-characterized projectiles to velocities exceeding 10 km/s. The masses of projectiles range between 0.1 - 15 g, and the design shows excellent scalability, reaching similar velocities across different projectile sizes. In the past, velocity measurements have been limited to muzzle velocity obtained via a high-speed videography upon the projectile exiting the launch tube. Recently, Photon Doppler Velocimetry (PDV) has demonstrated the ability to continuously measure in-bore velocity, even in the presence of significant blow-by of high temperature helium propellant past the projectile. While a single laser system sampled at 40 GS/s with a 13 GHz detector/scope bandwidth is limited to 8 km/s, a two-laser PDV system is developed that uses two lasers operating near 1550 nm to provide velocity measurement capabilities up to 16 km/s with the same bandwidth and sampling rate. The two-laser PDV system is used to obtain a continuous velocity history of the projectile throughout the entire launch cycle. These internal ballistics trajectories are used to compare different advanced concepts aimed at increasing the projectile velocity to well beyond 10 km/s.

Mineralogy and Astrobiology Detection Using Laser Remote Sensing Instrument

NASA Technical Reports Server (NTRS)

Abedin, M. Nurul; Bradley, Arthur T.; Sharma, Shiv K.; Misra, Anupam K.; Lucey, Paul G.; Mckay, Chistopher P.; Ismail, Syed; Sandford, Stephen P.

2015-01-01

A multispectral instrument based on Raman, laser-induced fluorescence (LIF), laser-induced breakdown spectroscopy (LIBS), and a lidar system provides high-fidelity scientific investigations, scientific input, and science operation constraints in the context of planetary field campaigns with the Jupiter Europa Robotic Lander and Mars Sample Return mission opportunities. This instrument conducts scientific investigations analogous to investigations anticipated for missions to Mars and Jupiter's icy moons. This combined multispectral instrument is capable of performing Raman and fluorescence spectroscopy out to a >100 m target distance from the rover system and provides single-wavelength atmospheric profiling over long ranges (>20 km). In this article, we will reveal integrated remote Raman, LIF, and lidar technologies for use in robotic and lander-based planetary remote sensing applications. Discussions are focused on recently developed Raman, LIF, and lidar systems in addition to emphasizing surface water ice, surface and subsurface minerals, organics, biogenic, biomarker identification, atmospheric aerosols and clouds distributions, i.e., near-field atmospheric thin layers detection for next robotic-lander based instruments to measure all the above-mentioned parameters. OCIS codes: (120.0280) Remote sensing and sensors; (130.0250) Optoelectronics; (280.3640) Lidar; (300.2530) Fluorescence, laser-induced; (300.6450) Spectroscopy, Raman; (300.6365) Spectroscopy, laser induced breakdown

Near-infrared image-guided laser ablation of dental decay

NASA Astrophysics Data System (ADS)

Tao, You-Chen; Fried, Daniel

2009-09-01

Image-guided laser ablation systems are now feasible for dentistry with the recent development of nondestructive high-contrast imaging modalities such as near-IR (NIR) imaging and optical coherence tomography (OCT) that are capable of discriminating between sound and demineralized dental enamel at the early stages of development. Our objective is to demonstrate that images of demineralized tooth surfaces have sufficient contrast to be used to guide a CO2 laser for the selective removal of natural and artificial caries lesions. NIR imaging and polarization-sensitive optical coherence tomography (PS-OCT) operating at 1310-nm are used to acquire images of natural lesions on extracted human teeth and highly patterned artificial lesions produced on bovine enamel. NIR and PS-OCT images are analyzed and converted to binary maps designating the areas on the samples to be removed by a CO2 laser to selectively remove the lesions. Postablation NIR and PS-OCT images confirmed preferential removal of demineralized areas with minimal damage to sound enamel areas. These promising results suggest that NIR and PS-OCT imaging systems can be integrated with a CO2 laser ablation system for the selective removal of dental caries.

Near-infrared image-guided laser ablation of dental decay

PubMed Central

Tao, You-Chen; Fried, Daniel

2009-01-01

Image-guided laser ablation systems are now feasible for dentistry with the recent development of nondestructive high-contrast imaging modalities such as near-IR (NIR) imaging and optical coherence tomography (OCT) that are capable of discriminating between sound and demineralized dental enamel at the early stages of development. Our objective is to demonstrate that images of demineralized tooth surfaces have sufficient contrast to be used to guide a CO2 laser for the selective removal of natural and artificial caries lesions. NIR imaging and polarization-sensitive optical coherence tomography (PS-OCT) operating at 1310-nm are used to acquire images of natural lesions on extracted human teeth and highly patterned artificial lesions produced on bovine enamel. NIR and PS-OCT images are analyzed and converted to binary maps designating the areas on the samples to be removed by a CO2 laser to selectively remove the lesions. Postablation NIR and PS-OCT images confirmed preferential removal of demineralized areas with minimal damage to sound enamel areas. These promising results suggest that NIR and PS-OCT imaging systems can be integrated with a CO2 laser ablation system for the selective removal of dental caries. PMID:19895146

Near-infrared image-guided laser ablation of dental decay.

PubMed

Tao, You-Chen; Fried, Daniel

2009-01-01

Image-guided laser ablation systems are now feasible for dentistry with the recent development of nondestructive high-contrast imaging modalities such as near-IR (NIR) imaging and optical coherence tomography (OCT) that are capable of discriminating between sound and demineralized dental enamel at the early stages of development. Our objective is to demonstrate that images of demineralized tooth surfaces have sufficient contrast to be used to guide a CO(2) laser for the selective removal of natural and artificial caries lesions. NIR imaging and polarization-sensitive optical coherence tomography (PS-OCT) operating at 1310-nm are used to acquire images of natural lesions on extracted human teeth and highly patterned artificial lesions produced on bovine enamel. NIR and PS-OCT images are analyzed and converted to binary maps designating the areas on the samples to be removed by a CO(2) laser to selectively remove the lesions. Postablation NIR and PS-OCT images confirmed preferential removal of demineralized areas with minimal damage to sound enamel areas. These promising results suggest that NIR and PS-OCT imaging systems can be integrated with a CO(2) laser ablation system for the selective removal of dental caries.

Quantum cascade lasers for defense and security

NASA Astrophysics Data System (ADS)

Day, Timothy; Pushkarsky, Michael; Caffey, Dave; Cecchetti, Kristen; Arp, Ron; Whitmore, Alex; Henson, Michael; Takeuchi, Eric B.

2013-10-01

Quantum cascade laser (QCL) systems are mature and at the vanguard of a new generation of products that support military applications such as Infrared Countermeasures (IRCM) and targeting. The demanding product requirements for aircraft platforms that include reduced size, weight, power consumption and cost (SWaP-C) extends to portable, battery powered handheld products. QCL technology operates throughout the mid-wave (MWIR) and long-wave (LWIR) infrared to provide new capabilities that leverage existing thermal imaging cameras. In addition to their suitability for aircraft platforms, QCL products are a natural fit to meet operator demands for small, lightweight pointer and beacon capabilities. Field-testing of high power, lightweight, battery operated devices has demonstrated their utility across a range of air and ground applications. This talk will present an overview of QCL technology and the Defense and Security products and capabilities that are enabled by it. This talk will also provide an overview of the extensive environmental and performance testing associated with products based on QCL technology.

Clinical dental application of Er:YAG laser for Class V cavity preparation.

PubMed

Matsumoto, K; Nakamura, Y; Mazeki, K; Kimura, Y

1996-06-01

Following the development of the ruby laser by Maiman in 1960, the Nd:YAG laser, the CO2 laser, the semiconductor laser, the He-Ne laser, excimer lasers, the argon laser, and finally the Er:YAG laser capable of cutting hard tissue easily were developed and have come to be applied clinically. In the present study, the Er:YAG laser emitting at a wavelength of 2.94 microns developed by Luxar was used for the clinical preparation of class V cavities. Parameters of 8 Hz and approx. 250 mJ/pulse maximum output were used for irradiation. Sixty teeth of 40 patients were used in this clinical study. The Er:YAG laser used in this study was found to be a system suitable for clinical application. No adverse reaction was observed in any of the cases. Class V cavity preparation was performed without inducing any pain in 48/60 cases (80%). All of the 12 cases that complained of mild or severe intraoperative pain had previously complained of cervical dentin hypersensibility during the preoperative examination. Cavity preparation was completed with this laser system in 58/60 cases (91.7%). No treatment-related clinical problems were observed during the follow-up period of approx. 30 days after cavity preparation and resin filling. Cavity preparation took between approx. 10 sec and 3 min and was related more or less to cavity size and depth. Overall clinical evaluation showed no safety problem with very good rating in 49 cases (81.7%).

Analysis of the Laser Propelled Lightcraft Vehicle

NASA Technical Reports Server (NTRS)

Feikema, Douglas

2000-01-01

Advanced propulsion research and technology require launch and space flight technologies, which can drastically reduce mission costs. Laser propulsion is a concept in which energy of a thrust producing reaction mass is supplied via beamed energy from an off-board power source. A variety of laser/beamed energy concepts were theoretically and experimentally investigated since the early 1970's. During the 1980's the Strategic Defense Initiative (SDI) research lead to the invention of the Laser Lightcraft concept. Based upon the Laser Lightcraft concept, the U.S. Air Force and NASA have jointly set out to develop technologies required for launching small payloads into Low Earth Orbit (LEO) for a cost of $1.0M or $1000/lb to $ 100/lb. The near term objectives are to demonstrate technologies and capabilities essential for a future earth to orbit launch capability. Laser propulsion offers the advantages of both high thrust and good specific impulse, I(sub sp), in excess of 1000 s. Other advantages are the simplicity and reliability of the engine because of few moving parts, simpler propellant feed system, and high specific impulse. Major limitations of this approach are the laser power available, absorption and distortion of the pulsed laser beam through the atmosphere, and coupling laser power into thrust throughout the flight envelope, The objective of this paper is to assist efforts towards optimizing the performance of the laser engine. In order to accomplish this goal (1) defocusing of the primary optic was investigated using optical ray tracing and (2), time dependent calculations were conducted of the optically induced blast wave to predict pressure and temperature in the vicinity of the cowl. Defocusing of the primary parabolic reflector causes blurring and reduction in the intensity of the laser ignition site on the cowl. However, because of the caustic effect of ray-tracing optics the laser radiation still forms a well-defined ignition line on the cowl. The blast wave calculations show reasonable agreement with previously published calculations and recent detailed CFD computations.

Intelligent hand-portable proliferation sensing system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dieckman, S.L.; Bostrom, G.A.; Waterfield, L.G.

1997-08-01

Argonne National Laboratory, with support from DOE`s Office of Nonproliferation and National Security, is currently developing an intelligent hand-portable sensor system. This system is designed specifically to support the intelligence community with the task of in-field sensing of nuclear proliferation and related activities. Based upon pulsed laser photo-ionization time-of-flight mass spectrometry technology, this novel sensing system is capable of quickly providing a molecular or atomic analysis of specimens. The system is capable of analyzing virtually any gas phase molecule, or molecule that can be induced into the gas phase by (for example) sample heating. This system has the unique advantagesmore » of providing unprecedented portability, excellent sensitivity, tremendous fieldability, and a high performance/cost ratio. The system will be capable of operating in a highly automated manner for on-site inspections, and easily modified for other applications such as perimeter monitoring aboard a plane or drone. The paper describes the sensing system.« less

Relative navigation requirements for automatic rendezvous and capture systems

NASA Technical Reports Server (NTRS)

Kachmar, Peter M.; Polutchko, Robert J.; Chu, William; Montez, Moises

1991-01-01

This paper will discuss in detail the relative navigation system requirements and sensor trade-offs for Automatic Rendezvous and Capture. Rendezvous navigation filter development will be discussed in the context of navigation performance requirements for a 'Phase One' AR&C system capability. Navigation system architectures and the resulting relative navigation performance for both cooperative and uncooperative target vehicles will be assessed. Relative navigation performance using rendezvous radar, star tracker, radiometric, laser and GPS navigation sensors during appropriate phases of the trajectory will be presented. The effect of relative navigation performance on the Integrated AR&C system performance will be addressed. Linear covariance and deterministic simulation results will be used. Evaluation of relative navigation and IGN&C system performance for several representative relative approach profiles will be presented in order to demonstrate the full range of system capabilities. A summary of the sensor requirements and recommendations for AR&C system capabilities for several programs requiring AR&C will be presented.

A Novel High Efficient Laser Transmitter Design for a Space-borne Ozone Differential Lidar (DIAL)

NASA Technical Reports Server (NTRS)

Edwards, W. C.; Chen, S.; Petway, L. B.; Marsh, W. D.; Storm, M. E.; Barnes, J. C.

2000-01-01

Development of a UV laser transmitter capable of operating from a space platform is a critical step in enabling global earth observations of aerosols and ozone at resolutions greater than current passive instrument capabilities. Tropospheric chemistry is well recognized as the next frontier for global atmospheric measurement. NASA Langley Research Center (LaRC) and the Canadian Space Agency (CSA) have jointly studied the requirements for a satellite based, global ozone monitoring instrument. The study, called Ozone Research using Advanced Cooperative Lidar Experiment (ORACLE) has defined the Differential Absorption Lidar (DIAL) instrument performance, weight and power, and configuration requirements for a space based measurement. In order to achieve the measurement resolution and acceptable signal-to-noise from lidar returns, 500mJ/pulse (5 Watts average power) is required at both 305-308nm and 315-320nm wavelengths. These are consecutive pulses, in a 10 Hz, double-pulsed format. The two wavelengths are used as the on- and off-lines for the ozone DIAL measurement. NASA Langley is currently developing technology for a UV laser transmitter capable of meeting the ORACLE requirements. Experimental efforts to date have shown that the UV generation scheme is viable, and that energies greater than l00mJ/pulse are possible. In this paper, we will briefly discuss the down select process for the proposed laser design, the study effort to date and the laser system design, including both primary and alternate approaches. We will describe UV laser technology that minimizes the total number of optical components (for enhanced reliability) as well as the number of UV coated optics required to transmit the light from the laser (for enhanced optical damage resistance). While the goal is to develop a laser that will produce 500 mJ of energy, we will describe an optional design that will produce output energies between 100 - 200 mJ/unit and techniques for combining multiple laser modules in order to transmit a minimum of 500mJ of UV energy in each pulse of the on- and off-line pulse pairs. This modular laser approach provides redundancy and significantly reduces development time, risk and cost when compared to the development of a single, 500mJ double-pulsed laser subsystem. Finally, we will summarize the laser development effort to date, including results that include the highest known UV energy ( 130 mJ at 320nm) ever produced by a solid-state laser operating in this wavelength region.

A Flexible Master Oscillator for a Thomson Scattering Pulse-Burst Laser System

NASA Astrophysics Data System (ADS)

den Hartog, D. J.; Young, W. C.

2015-11-01

A new master oscillator will be installed in the pulse-burst laser system used for high-rep-rate Thomson scattering on the MST experiment. This new master oscillator will enable pulse repetition rates up to 1 MHz, with the ability to program a burst of pulses with arbitrary and varying time separation between each pulse. In addition, the energy of each master oscillator pulse can be adjusted to compensate for gain variations in the power amplifier section of the laser system. This flexibility is accomplished by chopping a CW laser source with a high-bandwidth acousto-optic modulator (AOM). The laser source is a 1064 nm diode-pumped solid-state laser with continuous output power variable from 100 to 500 mW. The 2 mm diameter polarized beam is focused into the gallium phosphide crystal of the AOM, which deflects the beam by approximately 60 mrad. Beam deflection is controlled by a simple digital input pulse, and is capable of producing laser pulses of less than 20 ns width at repetition rates much greater than 1 MHz. These pulses from the output of the AOM will be collimated and propagated into the laser amplifier system, where they will be amplified to ~ 2 J/pulse and injected into the MST plasma. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences under Award Number DE-FC02-05ER54814, and by the National Science Foundation under Award Number PHY-0821899.

NASA/USRA advanced space design program: The laser powered interorbital vehicle

NASA Technical Reports Server (NTRS)

1989-01-01

A preliminary design is presented for a low-thrust Laser Powered Interorbital Vehicle (LPIV) intended for cargo transportation between an earth space station and a lunar base. The LPIV receives its power from two iodide laser stations, one orbiting the earth and the other located on the surface of the moon. The selected mission utilizes a spiral trajectory, characteristic of a low-thrust spacecraft, requiring 8 days for a lunar rendezvous and an additional 9 days for return. The ship's configuration consists primarily of an optical train, two hydrogen plasma engines, a 37.1 m box beam truss, a payload module, and fuel tanks. The total mass of the vehicle fully loaded is 63300 kg. A single plasma, regeneratively cooled engine design is incorporated into the two 500 N engines. These are connected to the spacecraft by turntables which allow the vehicle to thrust tangentially to the flight path. Proper collection and transmission of the laser beam to the thrust chambers is provided through the optical train. This system consists of the 23 m diameter primary mirror, a convex parabolic secondary mirror, a beam splitter and two concave parabolic tertiary mirrors. The payload bay is capable of carrying 18000 kg of cargo. The module is located opposite the primary mirror on the main truss. Fuel tanks carrying a maximum of 35000 kg of liquid hydrogen are fastened to tracks which allow the tanks to be moved perpendicular to the main truss. This capability is required to prevent the center of mass from moving out of the thrust vector line. The laser beam is located and tracked by means of an acquisition, pointing and tracking system which can be locked onto the space-based laser station. Correct orientation of the spacecraft with the laser beam is maintained by control moment gyros and reaction control rockets. Additionally an aerobrake configuration was designed to provide the option of using the atmospheric drag in place of propulsion for a return trajectory.

Assessing Capabilities of the High Energy Liquid Laser Area Defense System through Combat Simulations

DTIC Science & Technology

2008-03-01

it to strike targets with minimal collateral damage from a range of 15 kilometers. This stand -off type attack, made capable by the ATL, enables...levels they release a photon or quantum of light. This process continues until the light waves ’ strength builds and passes through the medium...mission level model. Lastly these models are classified by durability as standing models, or legacy models. Standing models are legacy models which have

Laser Range and Bearing Finder for Autonomous Missions

NASA Technical Reports Server (NTRS)

Granade, Stephen R.

2004-01-01

NASA has recently re-confirmed their interest in autonomous systems as an enabling technology for future missions. In order for autonomous missions to be possible, highly-capable relative sensor systems are needed to determine an object's distance, direction, and orientation. This is true whether the mission is autonomous in-space assembly, rendezvous and docking, or rover surface navigation. Advanced Optical Systems, Inc. has developed a wide-angle laser range and bearing finder (RBF) for autonomous space missions. The laser RBF has a number of features that make it well-suited for autonomous missions. It has an operating range of 10 m to 5 km, with a 5 deg field of view. Its wide field of view removes the need for scanning systems such as gimbals, eliminating moving parts and making the sensor simpler and space qualification easier. Its range accuracy is 1% or better. It is designed to operate either as a stand-alone sensor or in tandem with a sensor that returns range, bearing, and orientation at close ranges, such as NASA's Advanced Video Guidance Sensor. We have assembled the initial prototype and are currently testing it. We will discuss the laser RBF's design and specifications. Keywords: laser range and bearing finder, autonomous rendezvous and docking, space sensors, on-orbit sensors, advanced video guidance sensor

Wavelength-Scanning SPR Imaging Sensors Based on an Acousto-Optic Tunable Filter and a White Light Laser

PubMed Central

Zeng, Youjun; Wang, Lei; Wu, Shu-Yuen; He, Jianan; Qu, Junle; Li, Xuejin; Ho, Ho-Pui; Gu, Dayong; Gao, Bruce Zhi; Shao, Yonghong

2017-01-01

A fast surface plasmon resonance (SPR) imaging biosensor system based on wavelength interrogation using an acousto-optic tunable filter (AOTF) and a white light laser is presented. The system combines the merits of a wide-dynamic detection range and high sensitivity offered by the spectral approach with multiplexed high-throughput data collection and a two-dimensional (2D) biosensor array. The key feature is the use of AOTF to realize wavelength scan from a white laser source and thus to achieve fast tracking of the SPR dip movement caused by target molecules binding to the sensor surface. Experimental results show that the system is capable of completing a SPR dip measurement within 0.35 s. To the best of our knowledge, this is the fastest time ever reported in the literature for imaging spectral interrogation. Based on a spectral window with a width of approximately 100 nm, a dynamic detection range and resolution of 4.63 × 10−2 refractive index unit (RIU) and 1.27 × 10−6 RIU achieved in a 2D-array sensor is reported here. The spectral SPR imaging sensor scheme has the capability of performing fast high-throughput detection of biomolecular interactions from 2D sensor arrays. The design has no mechanical moving parts, thus making the scheme completely solid-state. PMID:28067766

Optical Phased Array Antennas using Coupled Vertical Cavity Surface Emitting Lasers

NASA Technical Reports Server (NTRS)

Mueller, Carl H.; Rojas, Roberto A.; Nessel, James A.; Miranda, Felix A.

2007-01-01

High data rate communication links are needed to meet the needs of NASA as well as other organizations to develop space-based optical communication systems. These systems must be robust to high radiation environments, reliable, and operate over a wide temperature range. Highly desirable features include beam steering capability, reconfigurability, low power consumption, and small aperture size. Optical communication links, using coupled vertical cavity surface emitting laser radiating elements are promising candidates for the transmit portion of these communication links. In this talk we describe a mission scenario, and how the antenna requirements are derived from the mission needs. We describe a potential architecture for this type of antenna, and outline the advantages and drawbacks of this approach relative to competing technologies. The technology we are proposing used coupled arrays of 1550 nm vertical cavity surface emitting lasers for transmission. The feasibility of coupling these arrays together, to form coherent high-power beams that can be modulated at data rates exceeding 1 Gbps, will be explored. We will propose an architecture that enables electronic beam steering, thus mitigating the need for ancillary acquisition, tracking and beam pointing equipment such as needed for current optical communicatin systems. The beam-steering capability we are proposing also opens the possibility of using this technology for inter-satellite communicatin links, and satellite-to-surface links.

Laser-based methods for the analysis of low molecular weight compounds in biological matrices.

PubMed

Kiss, András; Hopfgartner, Gérard

2016-07-15

Laser-based desorption and/or ionization methods play an important role in the field of the analysis of low molecular-weight compounds (LMWCs) because they allow direct analysis with high-throughput capabilities. In the recent years there were several new improvements in ionization methods with the emergence of novel atmospheric ion sources such as laser ablation electrospray ionization or laser diode thermal desorption and atmospheric pressure chemical ionization and in sample preparation methods with the development of new matrix compounds for matrix-assisted laser desorption/ionization (MALDI). Also, the combination of ion mobility separation with laser-based ionization methods starts to gain popularity with access to commercial systems. These developments have been driven mainly by the emergence of new application fields such as MS imaging and non-chromatographic analytical approaches for quantification. This review aims to present these new developments in laser-based methods for the analysis of low-molecular weight compounds by MS and several potential applications. Copyright © 2016 Elsevier Inc. All rights reserved.

EOID System Model Validation, Metrics, and Synthetic Clutter Generation

DTIC Science & Technology

2003-09-30

Our long-term goal is to accurately predict the capability of the current generation of laser-based underwater imaging sensors to perform Electro ... Optic Identification (EOID) against relevant targets in a variety of realistic environmental conditions. The models will predict the impact of

A user's guide to the Langley 16- by 24-inch water tunnel

NASA Technical Reports Server (NTRS)

Pendergraft, Odis C., Jr.; Neuhart, Dan H.; Kariya, Timmy T.

1992-01-01

The Langley 16 x 24 inch Water Tunnel is described in detail, along with all the supporting equipment used in its operation as a flow visualization test facility. These include the laser and incandescent lighting systems; and the photographic, video, and laser fluorescence anemometer systems used to make permanent records of the test results. This facility is a closed return water tunnel capable of test section velocities from 0 to 0.75 feet per second with flow through the 16 x 24 inch test section in a downward (vertical) direction. The velocity normally used for testing is 0.25 feet per second where the most uniform flow occurs, and is slow enough to easily observe flow phenomena such as vortex flow with the unaided eye. An overview is given of the operational characteristics, procedures, and capabilities of the water tunnel to potential users of the facility so that they may determine if the facility meets their needs for a planned study.

No moving parts safe & arm apparatus and method with monitoring and built-in-test for optical firing of explosive systems

DOEpatents

Hendrix, J.L.

1995-04-11

A laser initiated ordnance controller apparatus which provides a safe and arm scheme with no moving parts. The safe & arm apparatus provides isolation of firing energy to explosive devices using a combination of polarization isolation and control through acousto-optical deviation of laser energy pulses. The apparatus provides constant monitoring of the systems status and performs 100% built-in-test at any time prior to ordnance ignition without the risk of premature ignition or detonation. The apparatus has a computer controller, a solid state laser, an acousto-optic deflector and RF drive circuitry, built-in-test optics and electronics, and system monitoring capabilities. The optical system is completed from the laser beam power source to the pyrotechnic ordnance through fiber optic cabling, optical splitters and optical connectors. During operation of the apparatus, a command is provided by the computer controller and, simultaneous with laser flashlamp fire, the safe & arm device is opened for approximately 200 microseconds which allows the laser pulse to transmit through the device. The arm signal also energizes the laser power supply and activates the acousto-optical deflector. When the correct fire format command is received, the acousto-optic deflector moves to the selected event channel, and the channel is verified to ensure the system is pointing to the correct position. Laser energy is transmitted through the fiber where an ignitor or detonator designed to be sensitive to optical pulses is fired at the end of the fiber channel. Simultaneous event channels may also be utilized by optically splitting a single event channel. The built-in-test may be performed anytime prior to ordnance ignition. 6 figures.

No moving parts safe & arm apparatus and method with monitoring and built-in-test for optical firing of explosive systems

DOEpatents

Hendrix, James L.

1995-01-01

A laser initiated ordnance controller apparatus which provides a safe and m scheme with no moving parts. The safe & arm apparatus provides isolation of firing energy to explosive devices using a combination of polarization isolation and control through acousto-optical deviation of laser energy pulses. The apparatus provides constant monitoring of the systems status and performs 100% built-in-test at any time prior to ordnance ignition without the risk of premature ignition or detonation. The apparatus has a computer controller, a solid state laser, an acousto-optic deflector and RF drive circuitry, built-in-test optics and electronics, and system monitoring capabilities. The optical system is completed from the laser beam power source to the pyrotechnic ordnance through fiber optic cabling, optical splitters and optical connectors. During operation of the apparatus, a command is provided by the computer controller and, simultaneous with laser flashlamp fire, the safe & arm device is opened for approximately 200 microseconds which allows the laser pulse to transmit through the device. The arm signal also energizes the laser power supply and activates the acousto-optical deflector. When the correct fire format command is received, the acousto-optic deflector moves to the selected event channel, and the channel is verified to ensure the system is pointing to the correct position. Laser energy is transmitted through the fiber where an ignitor or detonator designed to be sensitive to optical pulses is fired at the end of the fiber channel. Simultaneous event channels may also be utilized by optically splitting a single event channel. The built-in-test may be performed anytime prior to ordnance ignition.

A novel fiber laser development for photoacoustic microscopy

NASA Astrophysics Data System (ADS)

Yavas, Seydi; Aytac-Kipergil, Esra; Arabul, Mustafa U.; Erkol, Hakan; Akcaalan, Onder; Eldeniz, Y. Burak; Ilday, F. Omer; Unlu, Mehmet B.

2013-03-01

Photoacoustic microscopy, as an imaging modality, has shown promising results in imaging angiogenesis and cutaneous malignancies like melanoma, revealing systemic diseases including diabetes, hypertension, tracing drug efficiency and assessment of therapy, monitoring healing processes such as wound cicatrization, brain imaging and mapping. Clinically, photoacoustic microscopy is emerging as a capable diagnostic tool. Parameters of lasers used in photoacoustic microscopy, particularly, pulse duration, energy, pulse repetition frequency, and pulse-to-pulse stability affect signal amplitude and quality, data acquisition speed and indirectly, spatial resolution. Lasers used in photoacoustic microscopy are typically Q-switched lasers, low-power laser diodes, and recently, fiber lasers. Significantly, the key parameters cannot be adjusted independently of each other, whereas microvasculature and cellular imaging, e.g., have different requirements. Here, we report an integrated fiber laser system producing nanosecond pulses, covering the spectrum from 600 nm to 1100 nm, developed specifically for photoacoustic excitation. The system comprises of Yb-doped fiber oscillator and amplifier, an acousto-optic modulator and a photonic-crystal fiber to generate supercontinuum. Complete control over the pulse train, including generation of non-uniform pulse trains, is achieved via the AOM through custom-developed field-programmable gate-array electronics. The system is unique in that all the important parameters are adjustable: pulse duration in the range of 1-3 ns, pulse energy up to 10 μJ, repetition rate from 50 kHz to 3 MHz. Different photocoustic imaging probes can be excited with the ultrabroad spectrum. The entire system is fiber-integrated; guided-beam-propagation rendersit misalignment free and largely immune to mechanical perturbations. The laser is robust, low-cost and built using readily available components.

Monolithic crystalline cladding microstructures for efficient light guiding and beam manipulation in passive and active regimes

PubMed Central

Jia, Yuechen; Cheng, Chen; Vázquez de Aldana, Javier R.; Castillo, Gabriel R.; Rabes, Blanca del Rosal; Tan, Yang; Jaque, Daniel; Chen, Feng

2014-01-01

Miniature laser sources with on-demand beam features are desirable devices for a broad range of photonic applications. Lasing based on direct-pump of miniaturized waveguiding active structures offers a low-cost but intriguing solution for compact light-emitting devices. In this work, we demonstrate a novel family of three dimensional (3D) photonic microstructures monolithically integrated in a Nd:YAG laser crystal wafer. They are produced by the femtosecond laser writing, capable of simultaneous light waveguiding and beam manipulation. In these guiding systems, tailoring of laser modes by both passive/active beam splitting and ring-shaped transformation are achieved by an appropriate design of refractive index patterns. Integration of graphene thin-layer as saturable absorber in the 3D laser structures allows for efficient passive Q-switching of tailored laser radiations which may enable miniature waveguiding lasers for broader applications. Our results pave a way to construct complex integrated passive and active laser circuits in dielectric crystals by using femtosecond laser written monolithic photonic chips. PMID:25100561

Repurposing mainstream CNC machine tools for laser-based additive manufacturing

NASA Astrophysics Data System (ADS)

Jones, Jason B.

2016-04-01

The advent of laser technology has been a key enabler for industrial 3D printing, known as Additive Manufacturing (AM). Despite its commercial success and unique technical capabilities, laser-based AM systems are not yet able to produce parts with the same accuracy and surface finish as CNC machining. To enable the geometry and material freedoms afforded by AM, yet achieve the precision and productivity of CNC machining, hybrid combinations of these two processes have started to gain traction. To achieve the benefits of combined processing, laser technology has been integrated into mainstream CNC machines - effectively repurposing them as hybrid manufacturing platforms. This paper reviews how this engineering challenge has prompted beam delivery innovations to allow automated changeover between laser processing and machining, using standard CNC tool changers. Handling laser-processing heads using the tool changer also enables automated change over between different types of laser processing heads, further expanding the breadth of laser processing flexibility in a hybrid CNC. This paper highlights the development, challenges and future impact of hybrid CNCs on laser processing.

Advanced E-O test capability for Army Next-Generation Automated Test System (NGATS)

NASA Astrophysics Data System (ADS)

Errea, S.; Grigor, J.; King, D. F.; Matis, G.; McHugh, S.; McKechnie, J.; Nehring, B.

2015-05-01

The Future E-O (FEO) program was established to develop a flexible, modular, automated test capability as part of the Next Generation Automatic Test System (NGATS) program to support the test and diagnostic needs of currently fielded U.S. Army electro-optical (E-O) devices, as well as being expandable to address the requirements of future Navy, Marine Corps and Air Force E-O systems. Santa Barbara infrared (SBIR) has designed, fabricated, and delivered three (3) prototype FEO for engineering and logistics evaluation prior to anticipated full-scale production beginning in 2016. In addition to presenting a detailed overview of the FEO system hardware design, features and testing capabilities, the integration of SBIR's EO-IR sensor and laser test software package, IRWindows 4™, into FEO to automate the test execution, data collection and analysis, archiving and reporting of results is also described.

High accuracy LADAR scene projector calibration sensor development

NASA Astrophysics Data System (ADS)

Kim, Hajin J.; Cornell, Michael C.; Naumann, Charles B.; Bowden, Mark H.

2008-04-01

A sensor system for the characterization of infrared laser radar scene projectors has been developed. Available sensor systems do not provide sufficient range resolution to evaluate the high precision LADAR projector systems developed by the U.S. Army Research, Development and Engineering Command (RDECOM) Aviation and Missile Research, Development and Engineering Center (AMRDEC). With timing precision capability to a fraction of a nanosecond, it can confirm the accuracy of simulated return pulses from a nominal range of up to 6.5 km to a resolution of 4cm. Increased range can be achieved through firmware reconfiguration. Two independent amplitude triggers measure both rise and fall time providing a judgment of pulse shape and allowing estimation of the contained energy. Each return channel can measure up to 32 returns per trigger characterizing each return pulse independently. Currently efforts include extending the capability to 8 channels. This paper outlines the development, testing, capabilities and limitations of this new sensor system.

BELINDA: Broadband Emission Lidar with Narrowband Determination of Absorption. A new concept for measuring water vapor and temperature profiles

NASA Technical Reports Server (NTRS)

Theopold, F. A.; Weitkamp, C.; Michaelis, W.

1992-01-01

We present a new concept for differential absorption lidar measurements of water vapor and temperature profiles. The idea is to use one broadband emission laser and a narrowband filter system for separation of the 'online' and 'offline' return signals. It is shown that BELINDA offers improvements as to laser emission shape and stability requirements, background suppression, and last and most important a significant reduction of the influence of Rayleigh scattering. A suitably designed system based on this concept is presented, capable of measuring water vapor or temperature profiles throughout the planetary boundary layer.

Directed energy missions for planetary defense

NASA Astrophysics Data System (ADS)

Lubin, Philip; Hughes, Gary B.; Eskenazi, Mike; Kosmo, Kelly; Johansson, Isabella E.; Griswold, Janelle; Pryor, Mark; O'Neill, Hugh; Meinhold, Peter; Suen, Jonathan; Riley, Jordan; Zhang, Qicheng; Walsh, Kevin; Melis, Carl; Kangas, Miikka; Motta, Caio; Brashears, Travis

2016-09-01

Directed energy for planetary defense is now a viable option and is superior in many ways to other proposed technologies, being able to defend the Earth against all known threats. This paper presents basic ideas behind a directed energy planetary defense system that utilizes laser ablation of an asteroid to impart a deflecting force on the target. A conceptual philosophy called DE-STAR, which stands for Directed Energy System for Targeting of Asteroids and exploration, is an orbiting stand-off system, which has been described in other papers. This paper describes a smaller, stand-on system known as DE-STARLITE as a reduced-scale version of DE-STAR. Both share the same basic heritage of a directed energy array that heats the surface of the target to the point of high surface vapor pressure that causes significant mass ejection thus forming an ejection plume of material from the target that acts as a rocket to deflect the object. This is generally classified as laser ablation. DE-STARLITE uses conventional propellant for launch to LEO and then ion engines to propel the spacecraft from LEO to the near-Earth asteroid (NEA). During laser ablation, the asteroid itself provides the propellant source material; thus a very modest spacecraft can deflect an asteroid much larger than would be possible with a system of similar mission mass using ion beam deflection (IBD) or a gravity tractor. DE-STARLITE is capable of deflecting an Apophis-class (325 m diameter) asteroid with a 1- to 15-year targeting time (laser on time) depending on the system design. The mission fits within the rough mission parameters of the Asteroid Redirect Mission (ARM) program in terms of mass and size. DE-STARLITE also has much greater capability for planetary defense than current proposals and is readily scalable to match the threat. It can deflect all known threats with sufficient warning.

Single mode pulsed dye laser oscillator

DOEpatents

Hackel, Richard P.

1992-01-01

A single mode pulsed dye laser oscillator is disclosed. The dye laser oscillator provides for improved power efficiency by reducing the physical dimensions of the overall laser cavity, which improves frequency selection capability.

Research on online 3D laser scanner dimensional measurement system for heavy high-temperature forgings

NASA Astrophysics Data System (ADS)

Zhu, Jingguo; Li, Menglin; Jiang, Yan; Xie, Tianpeng; Li, Feng; Jiang, Chenghao; Liu, Ruqing; Meng, Zhe

2017-10-01

Online 3-D laser-scanner is a non-contact measurement system with high speed, high precision and easy operation, which can be used to measure heavy and high-temperature forgings. But the current online laser measurement system is mainly a mobile light indicator, which can only be used in the limited environment and lacks the capability of 3-D accurate measurement. This paper mainly introduces the structure of the online high-speed real-time 3-D measurement for heavy high-temperature forgings of Academy of Opto-Electronics (AOE), Chinese Academy of Sciences. Combining TOF pulse distance measurement with hybrid scan mode, the system can scan and acquire point cloud data of an area of 20m×10m with a 75°×40° field of view at the distance of 20m. The entire scanning time is less than 5 seconds with an accuracy of 8mm, which can meet the online dimensional measurement requirements of heavy high-temperature forgings.

Standoff detection of explosives and chemical agents using broadly tuned external-cavity quantum cascade lasers (EC-QCLs)

NASA Astrophysics Data System (ADS)

Takeuchi, Eric B.; Rayner, Timothy; Weida, Miles; Crivello, Salvatore; Day, Timothy

2007-10-01

Civilian soft targets such as transportation systems are being targeted by terrorists using IEDs and suicide bombers. Having the capability to remotely detect explosives, precursors and other chemicals would enable these assets to be protected with minimal interruption of the flow of commerce. Mid-IR laser technology offers the potential to detect explosives and other chemicals in real-time and from a safe standoff distance. While many of these agents possess "fingerprint" signatures in the mid-IR (i.e. in the 3-20 micron regime), their effective interrogation by a practical, field-deployable system has been limited by size, complexity, reliability and cost constraints of the base laser technology. Daylight Solutions has addressed these shortcomings by developing compact, portable, broadly tunable mid-IR laser sources based upon external-cavity quantum cascade technology. This technology is now being applied by Daylight in system level architectures for standoff and remote detection of explosives, precursors and chemical agents. Several of these architectures and predicted levels of performance will be presented.

Digital micromirror device-based laser-illumination Fourier ptychographic microscopy

PubMed Central

Kuang, Cuifang; Ma, Ye; Zhou, Renjie; Lee, Justin; Barbastathis, George; Dasari, Ramachandra R.; Yaqoob, Zahid; So, Peter T. C.

2015-01-01

We report a novel approach to Fourier ptychographic microscopy (FPM) by using a digital micromirror device (DMD) and a coherent laser source (532 nm) for generating spatially modulated sample illumination. Previously demonstrated FPM systems are all based on partially-coherent illumination, which offers limited throughput due to insufficient brightness. Our FPM employs a high power coherent laser source to enable shot-noise limited high-speed imaging. For the first time, a digital micromirror device (DMD), imaged onto the back focal plane of the illumination objective, is used to generate spatially modulated sample illumination field for ptychography. By coding the on/off states of the micromirrors, the illumination plane wave angle can be varied at speeds more than 4 kHz. A set of intensity images, resulting from different oblique illuminations, are used to numerically reconstruct one high-resolution image without obvious laser speckle. Experiments were conducted using a USAF resolution target and a fiber sample, demonstrating high-resolution imaging capability of our system. We envision that our approach, if combined with a coded-aperture compressive-sensing algorithm, will further improve the imaging speed in DMD-based FPM systems. PMID:26480361

Digital micromirror device-based laser-illumination Fourier ptychographic microscopy.

PubMed

Kuang, Cuifang; Ma, Ye; Zhou, Renjie; Lee, Justin; Barbastathis, George; Dasari, Ramachandra R; Yaqoob, Zahid; So, Peter T C

2015-10-19

We report a novel approach to Fourier ptychographic microscopy (FPM) by using a digital micromirror device (DMD) and a coherent laser source (532 nm) for generating spatially modulated sample illumination. Previously demonstrated FPM systems are all based on partially-coherent illumination, which offers limited throughput due to insufficient brightness. Our FPM employs a high power coherent laser source to enable shot-noise limited high-speed imaging. For the first time, a digital micromirror device (DMD), imaged onto the back focal plane of the illumination objective, is used to generate spatially modulated sample illumination field for ptychography. By coding the on/off states of the micromirrors, the illumination plane wave angle can be varied at speeds more than 4 kHz. A set of intensity images, resulting from different oblique illuminations, are used to numerically reconstruct one high-resolution image without obvious laser speckle. Experiments were conducted using a USAF resolution target and a fiber sample, demonstrating high-resolution imaging capability of our system. We envision that our approach, if combined with a coded-aperture compressive-sensing algorithm, will further improve the imaging speed in DMD-based FPM systems.

Imaging strategies for the study of gas turbine spark ignition

NASA Astrophysics Data System (ADS)

Gord, James R.; Tyler, Charles; Grinstead, Keith D., Jr.; Fiechtner, Gregory J.; Cochran, Michael J.; Frus, John R.

1999-10-01

Spark-ignition systems play a critical role in the performance of essentially all gas turbine engines. These devices are responsible for initiating the combustion process that sustains engine operation. Demanding applications such as cold start and high-altitude relight require continued enhancement of ignition systems. To characterize advanced ignition systems, we have developed a number of laser-based diagnostic techniques configured for ultrafast imaging of spark parameters including emission, density, temperature, and species concentration. These diagnostics have been designed to exploit an ultrafast- framing charge-coupled-device (CCD) camera and high- repetition-rate laser sources including mode-locked Ti:sapphire oscillators and regenerative amplifiers. Spontaneous-emission and laser-shlieren measurements have been accomplished with this instrumentation and the result applied to the study of a novel Unison Industries spark igniter that shows great promise for improved cold-start and high-altitude-relight capability as compared to that of igniters currently in use throughout military and commercial fleets. Phase-locked and ultrafast real-time imaging strategies are explored, and details of the imaging instrumentation, particularly the CCD camera and laser sources, are discussed.

Solid-State, High Energy 2-Micron Laser Development for Space-Based Remote Sensing

NASA Technical Reports Server (NTRS)

Singh, Upendra N.

2010-01-01

Lidar (light detection and ranging) remote sensing enjoys the advantages of excellent vertical and horizontal resolution; pointing capability; a signal source independent from natural light; and control and knowledge of transmitted wavelength, pulse shape, and polarization and received polarization. Lidar in space is an emerging technology now being developing to fit applications where passive sensors cannot meet current measurement requirements. Technical requirements for space lidar are more demanding than for ground-based or airborne systems. Perhaps the most distinguishing characteristics of space lidars are the environmental requirements. Space lidar systems must be specially designed to survive the mechanical vibration loads of launch and operate in the vacuum of space where exposure to ionizing radiation limits the electronic components available. Finally, space lidars must be designed to be highly reliable because they must operate without the need for repair or adjustment. Lifetime requirements tend to be important drivers of the overall system design. The maturity of the required technologies is a key to the development of any space lidar system. NASA entered a new era in the 1990 s with the approval of several space-based remote sensing missions employing laser radar (lidar) techniques. Following the steps of passive remote sensing and then active radar remote sensing, lidar sensors were a logical next step, providing independence from natural light sources, and better spatial resolution and smaller sensor size than radar sensors. The shorter electromagnetic wavelengths of laser light also allowed signal reflectance from air molecules and aerosol particles. The smaller receiver apertures allowed the concept of scanning the sensor field of view. However, technical problems with several space-based lidar missions during that decade led to concern at NASA about the risk of lidar missions. An external panel was convened to make recommendations to NASA. Their report in 2000 strongly advocated that NASA maintain in-house laser and lidar capability, and that NASA should work to lower the technology risk for all future lidar missions. A multi-Center NASA team formulated an integrated NASA strategy to provide the technology and maturity of systems necessary to make Lidar/Laser systems viable for space-based study and monitoring of the Earth's atmosphere. In 2002 the NASA Earth Science Enterprise (ESE) and Office of Aerospace Technology (OAT) created the Laser Risk Reduction Program (LRRP) and directed NASA Langley Research Center (LaRC) and Goddard Space Flight Center to carry out synergistic and complementary research towards solid-state lasers/lidars developments for space-based remote sensing applications.

Digitally controlled chirped pulse laser for sub-terahertz-range fiber structure interrogation.

PubMed

Chen, Zhen; Hefferman, Gerald; Wei, Tao

2017-03-01

This Letter reports a sweep velocity-locked laser pulse generator controlled using a digital phase-locked loop (DPLL) circuit. This design is used for the interrogation of sub-terahertz-range fiber structures for sensing applications that require real-time data collection with millimeter-level spatial resolution. A distributed feedback laser was employed to generate chirped laser pulses via injection current modulation. A DPLL circuit was developed to lock the optical frequency sweep velocity. A high-quality linearly chirped laser pulse with a frequency excursion of 117.69 GHz at an optical communication band was demonstrated. The system was further adopted to interrogate a continuously distributed sub-terahertz-range fiber structure (sub-THz-fs) for sensing applications. A strain test was conducted in which the sub-THz-fs showed a linear response to longitudinal strain change with predicted sensitivity. Additionally, temperature testing was conducted in which a heat source was used to generate a temperature distribution along the fiber structure to demonstrate its distributed sensing capability. A Gaussian temperature profile was measured using the described system and tracked in real time, as the heat source was moved.

Down-Bore Two-Laser Heterodyne Velocimetry of an Implosion-Driven Hypervelocity Launcher

NASA Astrophysics Data System (ADS)

Hildebrand, Myles; Huneault, Justin; Loiseau, Jason; Higgins, Andrew J.

2015-06-01

The implosion-driven launcher uses explosives to shock-compress helium, driving well-characterized projectiles to velocities exceeding 10 km/s. The masses of projectiles range between 0.1 - 10 g, and the design shows excellent scalability, reaching similar velocities across different projectile sizes. In the past, velocity measurements have been limited to muzzle velocity obtained via a high-speed videography upon the projectile exiting the launch tube. Recently, Photonic Doppler Velocimetry (PDV) has demonstrated the ability to continuously measure in-bore velocity, even in the presence of significant blow-by of high temperature helium propellant past the projectile. While a single-laser PDV is limited to approximately 8 km/s, a two-laser PDV system is developed that uses two lasers operating near 1550 nm to provide velocity measurement capabilities up to 16 km/s. The two laser PDV system is used to obtain a continuous velocity history of the projectile throughout the entire launch cycle. These continuous velocity data are used to validate models of the launcher cycle and compare different advanced concepts aimed at increasing the projectile velocity to well beyond 10 km/s.

Development and first experimental tests of Faraday cup array.

PubMed

Prokůpek, J; Kaufman, J; Margarone, D; Krůs, M; Velyhan, A; Krása, J; Burris-Mog, T; Busold, S; Deppert, O; Cowan, T E; Korn, G

2014-01-01

A new type of Faraday cup, capable of detecting high energy charged particles produced in a high intensity laser-matter interaction environment, has recently been developed and demonstrated as a real-time detector based on the time-of-flight technique. An array of these Faraday cups was designed and constructed to cover different observation angles with respect to the target normal direction. Thus, it allows reconstruction of the spatial distribution of ion current density in the subcritical plasma region and the ability to visualise its time evolution through time-of-flight measurements, which cannot be achieved with standard laser optical interferometry. This is a unique method for two-dimensional visualisation of ion currents from laser-generated plasmas. A technical description of the new type of Faraday cup is introduced along with an ad hoc data analysis procedure. Experimental results obtained during campaigns at the Petawatt High-Energy Laser for Heavy Ion Experiments (GSI, Darmstadt) and at the Prague Asterix Laser System (AS CR) are presented. Advantages and limitations of the used diagnostic system are discussed.

Bladder welding in rats using controlled temperature CO2 laser system.

PubMed

Lobik, L; Ravid, A; Nissenkorn, I; Kariv, N; Bernheim, J; Katzir, A

1999-05-01

Laser tissue welding has potential advantages over conventional suture closure of surgical wounds. It is a noncontact technique that introduces no foreign body and limits the possibility of infections and complications. The closure could be immediately watertight and the procedure may be less traumatic, faster and easier. In spite of these positives laser welding has not yet been approved for wide use. The problem in the clinical implementation of this technique arises from the difficulty in defining the conditions under which a highly reliable weld is formed. We have assumed that the successful welding of tissues depends on the ability to monitor and control the surface temperature during the procedure, thereby avoiding underheating or overheating. The purpose of this work was to develop a laser system for reliable welding of urinary tract tissues under good temperature control. We have developed a "smart" laser system that is capable of a dual role: transmitting CO2 laser power for tissue heating, and noncontact (radiometric) temperature monitoring and control. Bladder opening (cystotomy) was performed in 38 rats. Thirty-three animals underwent laser welding. In 5 rats (control group) the bladder wound was closed with one layer of continuous 6-0 dexon sutures. Reliable welding was obtained when the surface temperature was kept at 71 + 5C. Quality of weld was controlled immediately after operation. The rats were sacrificed on days 2, 10 and 30 for histological study. Bladder closure using the laser welding system was successful in 31/33 (94%) animals. Histological examination revealed an excellent welding and healing of the tissue. Efficiency of laser welding of urinary bladder in rats was confirmed by high survival rate and quality of scar that was demonstrated by clinical and histological examinations. In the future, optimal laser welding conditions will be studied in larger animals, using CO2 lasers and other lasers, with deeper radiation penetration into tissues.

Single mode pulsed dye laser oscillator

DOEpatents

Hackel, R.P.

1992-11-24

A single mode pulsed dye laser oscillator is disclosed. The dye laser oscillator provides for improved power efficiency by reducing the physical dimensions of the overall laser cavity, which improves frequency selection capability. 6 figs.

ORION laser target diagnostics.

PubMed

Bentley, C D; Edwards, R D; Andrew, J E; James, S F; Gardner, M D; Comley, A J; Vaughan, K; Horsfield, C J; Rubery, M S; Rothman, S D; Daykin, S; Masoero, S J; Palmer, J B; Meadowcroft, A L; Williams, B M; Gumbrell, E T; Fyrth, J D; Brown, C R D; Hill, M P; Oades, K; Wright, M J; Hood, B A; Kemshall, P

2012-10-01

The ORION laser facility is one of the UK's premier laser facilities which became operational at AWE in 2010. Its primary mission is one of stockpile stewardship, ORION will extend the UK's experimental plasma physics capability to the high temperature, high density regime relevant to Atomic Weapons Establishment's (AWE) program. The ORION laser combines ten laser beams operating in the ns regime with two sub ps short pulse chirped pulse amplification beams. This gives the UK a unique combined long pulse/short pulse laser capability which is not only available to AWE personnel but also gives access to our international partners and visiting UK academia. The ORION laser facility is equipped with a comprehensive suite of some 45 diagnostics covering optical, particle, and x-ray diagnostics all able to image the laser target interaction point. This paper focuses on a small selection of these diagnostics.

The invisible extension cord

NASA Astrophysics Data System (ADS)

Gunn, Stanley V.

1998-01-01

The term, ``power beaming'', creates an image of a beam of focused electromagnetic radiation, possessing good transmission characteristics and sufficient intensity to effect the delivery of meaningful amounts of power to a designated receiver. High power, free-electron lasers are well suited for long range transmission of their laser beam to designated space receivers because their selective near infrared wave length can be adjusted to match the absorption characteristics of the receiver's photo voltaic cells. The typical system envisioned is comprised of a 200 kw free electron laser, possessing an over-all efficiency of 10%, and an optical beam director system equipped with appropriate tracking and atmospheric compensation capabilities. Such an installation located at four to five appropriate locations around the earth could provide remarkable benefits to the projected power demands for transfer and maneuvering into orbit and for operating future fleets of satellites.

Nonlinear pulse compression stage delivering 43-W few-cycle pulses with GW peak-power at 2-μm wavelength

NASA Astrophysics Data System (ADS)

Gebhardt, Martin; Gaida, Christian; Heuermann, T.; Stutzki, F.; Jauregui, C.; Antonio-Lopez, J.; Schüuzgen, A.; Amezcua-Correa, R.; Tünnermann, A.; Limpert, J.

2018-02-01

In this contribution we demonstrate the nonlinear pulse compression of an ultrafast thulium-doped fiber laser down to 14 fs FWHM duration (sub-3 optical cycles) at a record average power of 43 W and 34.5 μJ pulse energy. To the best of our knowledge, we present the highest average power few-cycle laser source at 2 μm wavelength. This performance level in combination with GW-class peak power makes our laser source extremely interesting for driving high-harmonic generation or for generating mid-infrared frequency combs via intra-pulse frequency down-conversion at an unprecedented average power. The experiments were enabled by an ultrafast thulium-doped fiber laser delivering 110 fs pulses at high repetition rates, and an argon gas-filled antiresonant hollow-core fiber (ARHCF) with excellent transmission and weak anomalous dispersion, leading to the self-compression of the pulses. We have shown that ARHCFs are well-suited for nonlinear pulse compression around 2 μm wavelength and that this concept features excellent power handling capabilities. Based on this result, we discuss the next steps for energy and average power scaling including upscaling the fiber dimensions in order to fully exploit the capabilities of our laser system, which can deliver several GW of peak power. This way, a 100 W-class laser source with mJ-level few-cycle pulses at 2 μm wavelength is feasible in the near future.

Three-dimensional laser radar modeling

NASA Astrophysics Data System (ADS)

Steinvall, Ove K.; Carlsson, Tomas

2001-09-01

Laser radars have the unique capability to give intensity and full 3-D images of an object. Doppler lidars can give velocity and vibration characteristics of an objects. These systems have many civilian and military applications such as terrain modelling, depth sounding, object detection and classification as well as object positioning. In order to derive the signal waveform from the object one has to account for the laser pulse time characteristics, media effects such as the atmospheric attenuation and turbulence effects or scattering properties, the target shape and reflection (BRDF), speckle noise together with the receiver and background noise. Finally the type of waveform processing (peak detection, leading edge etc.) is needed to model the sensor output to be compared with observations. We have developed a computer model which models performance of a 3-D laser radar. We will give examples of signal waveforms generated from model different targets calculated by integrating the laser beam profile in space and time over the target including reflection characteristics during different speckle and turbulence conditions. The result will be of help when designing and using new laser radar systems. The importance of different type of signal processing of the waveform in order to fulfil performance goals will be shown.

Development of an Advanced Aidman Vision Screener (AVS) for selective assessment of outer and inner laser induced retinal injury

NASA Astrophysics Data System (ADS)

Boye, Michael W.; Zwick, Harry; Stuck, Bruce E.; Edsall, Peter R.; Akers, Andre

2007-02-01

The need for tools that can assist in evaluating visual function is an essential and a growing requirement as lasers on the modern battlefield mature and proliferate. The requirement for rapid and sensitive vision assessment under field conditions produced the USAMRD Aidman Vision Screener (AVS), designed to be used as a field diagnostic tool for assessing laser induced retinal damage. In this paper, we describe additions to the AVS designed to provide a more sensitive assessment of laser induced retinal dysfunction. The AVS incorporates spectral LogMar Acuity targets without and with neural opponent chromatic backgrounds. Thus, it provides the capability of detecting selective photoreceptor damage and its functional consequences at the level of both the outer and inner retina. Modifications to the original achromatic AVS have been implemented to detect selective cone system dysfunction by providing LogMar acuity Landolt rings associated with the peak spectral absorption regions of the S (short), M (middle), and L (long) wavelength cone photoreceptor systems. Evaluation of inner retinal dysfunction associated with selective outer cone damage employs LogMar spectral acuity charts with backgrounds that are neurally opponent. Thus, the AVS provides the capability to assess the effect of selective cone dysfunction on the normal neural balance at the level of the inner retinal interactions. Test and opponent background spectra have been optimized by using color space metrics. A minimal number of three AVS evaluations will be utilized to provide an estimate of false alarm level.

Two Temperature Modeling and Experimental Measurements of Laser Sustained Hydrogen Plasmas

DTIC Science & Technology

1993-05-01

4 1.3 Theoretical Background .................................................................. 7 1.4...typically produce low specific impulses with an upper limit of approximately 450 seconds. The theoretical chamber temperature in such a system can be as...systems are theoretically capable of producing moderate thrusts (> 1 kN) with specific impulses in excess of 1000 seconds for 10 MW input power. This

Fusion reactor pumped laser

DOEpatents

Jassby, D.L.

1987-09-04

A nuclear pumped laser capable of producing long pulses of very high power laser radiation is provided. A toroidal fusion reactor provides energetic neutrons which are slowed down by a moderator. The moderated neutrons are converted to energetic particles capable of pumping a lasing medium. The lasing medium is housed in an annular cell surrounding the reactor. The cell includes an annular reflecting mirror at the bottom and an annular output window at the top. A neutron reflector is disposed around the cell to reflect escaping neutrons back into the cell. The laser radiation from the annular window is focused onto a beam compactor which generates a single coherent output laser beam. 10 figs.

Fusion reactor pumped laser

DOEpatents

Jassby, Daniel L.

1988-01-01

A nuclear pumped laser capable of producing long pulses of very high power laser radiation is provided. A toroidal fusion reactor provides energetic neutrons which are slowed down by a moderator. The moderated neutrons are converted to energetic particles capable of pumping a lasing medium. The lasing medium is housed in an annular cell surrounding the reactor. The cell includes an annular reflecting mirror at the bottom and an annular output window at the top. A neutron reflector is disposed around the cell to reflect escaping neutrons back into the cell. The laser radiation from the annular window is focused onto a beam compactor which generates a single coherent output laser beam.

Toward the development of a low-cost laser Doppler module for ophthalmic microscopes

NASA Astrophysics Data System (ADS)

Cattini, Stefano; Rovati, Luigi

2012-03-01

A laser Doppler module easily integrated into a commercial ophthalmic microscope is proposed. Such setup adds flow measurement capability to standard visual inspection of the fundus. The proposed instrument may provide important clinical information such as the detection of vessel occlusion provided by surgical treatments (i.e. photocoagulation). The measuring system is based on a self-mixing laser diode Doppler flowmeter (SM-DF). Reduced costs, easy implementation and small size represent the main features of SM-DF. Moreover, this technique offers the advantage to have the excitation and measurement beams spatially overlapped, thus both overcoming the alignment difficulty of traditional laser Doppler flowmeter and, well fitting with to limited optical aperture of the pupil. Thanks to an on-board DSP-microcontroller, the optoelectronic module directly estimates the blood flow; USB connection and an ad-hoc developed user-friendly software interface allow displaying the result on a personal computer. Preliminary test demonstrates the applicability of the proposed measuring system.

Real-time dual-comb spectroscopy with a free-running bidirectionally mode-locked fiber laser

NASA Astrophysics Data System (ADS)

Mehravar, S.; Norwood, R. A.; Peyghambarian, N.; Kieu, K.

2016-06-01

Dual-comb technique has enabled exciting applications in high resolution spectroscopy, precision distance measurements, and 3D imaging. Major advantages over traditional methods can be achieved with dual-comb technique. For example, dual-comb spectroscopy provides orders of magnitude improvement in acquisition speed over standard Fourier-transform spectroscopy while still preserving the high resolution capability. Wider adoption of the technique has, however, been hindered by the need for complex and expensive ultrafast laser systems. Here, we present a simple and robust dual-comb system that employs a free-running bidirectionally mode-locked fiber laser operating at telecommunication wavelength. Two femtosecond frequency combs (with a small difference in repetition rates) are generated from a single laser cavity to ensure mutual coherent properties and common noise cancellation. As the result, we have achieved real-time absorption spectroscopy measurements without the need for complex servo locking with accurate frequency referencing, and relatively high signal-to-noise ratio.

Spectrally Tailored Pulsed Thulium Fiber Laser System for Broadband Lidar CO2 Sensing

NASA Technical Reports Server (NTRS)

Heaps, William S.; Georgieva, Elena M.; McComb, Timothy S.; Cheung, Eric C.; Hassell, Frank R.; Baldauf, Brian K.

2011-01-01

Thulium doped pulsed fiber lasers are capable of meeting the spectral, temporal, efficiency, size and weight demands of defense and civil applications for pulsed lasers in the eye-safe spectral regime due to inherent mechanical stability, compact "all-fiber" master oscillator power amplifier (MOPA) architectures, high beam quality and efficiency. Thulium fiber's longer operating wavelength allows use of larger fiber cores without compromising beam quality, increasing potential single aperture pulse energies. Applications of these lasers include eye-safe laser ranging, frequency conversion to longer or shorter wavelengths for IR countermeasures and sensing applications with otherwise tough to achieve wavelengths and detection of atmospheric species including CO2 and water vapor. Performance of a portable thulium fiber laser system developed for CO2 sensing via a broadband lidar technique with an etalon based sensor will be discussed. The fielded laser operates with approximately 280 J pulse energy in 90-150ns pulses over a tunable 110nm spectral range and has a uniquely tailored broadband spectral output allowing the sensing of multiple CO2 lines simultaneously, simplifying future potentially space based CO2 sensing instruments by reducing the number and complexity of lasers required to carry out high precision sensing missions. Power scaling and future "all fiber" system configurations for a number of ranging, sensing, countermeasures and other yet to be defined applications by use of flexible spectral and temporal performance master oscillators will be discussed. The compact, low mass, robust, efficient and readily power scalable nature of "all-fiber" thulium lasers makes them ideal candidates for use in future space based sensing applications.

[Nondestructive Evaluation (NDE) Capabilities

NASA Technical Reports Server (NTRS)

Born, Martin

2010-01-01

These poster boards display the United Space Alliance's (USA) systems and equipment used for Nondestructive Evaluation. These include: (1) the Robotic Inspection Facility, (2) CAT-Scan and Laminography, (3) Laser Surface Profilometry, (4) Remote Eddy Current, (5) Ultrasonic Phased Array, (7) Infrared Flash Thermography, and (8) Backscatter X-Ray (BSX)

High Resolution Airborne Laser Scanning and Hyperspectral Imaging with a Small Uav Platform

NASA Astrophysics Data System (ADS)

Gallay, Michal; Eck, Christoph; Zgraggen, Carlo; Kaňuk, Ján; Dvorný, Eduard

2016-06-01

The capabilities of unmanned airborne systems (UAS) have become diverse with the recent development of lightweight remote sensing instruments. In this paper, we demonstrate our custom integration of the state-of-the-art technologies within an unmanned aerial platform capable of high-resolution and high-accuracy laser scanning, hyperspectral imaging, and photographic imaging. The technological solution comprises the latest development of a completely autonomous, unmanned helicopter by Aeroscout, the Scout B1-100 UAV helicopter. The helicopter is powered by a gasoline two-stroke engine and it allows for integrating 18 kg of a customized payload unit. The whole system is modular providing flexibility of payload options, which comprises the main advantage of the UAS. The UAS integrates two kinds of payloads which can be altered. Both payloads integrate a GPS/IMU with a dual GPS antenna configuration provided by OXTS for accurate navigation and position measurements during the data acquisition. The first payload comprises a VUX-1 laser scanner by RIEGL and a Sony A6000 E-Mount photo camera. The second payload for hyperspectral scanning integrates a push-broom imager AISA KESTREL 10 by SPECIM. The UAS was designed for research of various aspects of landscape dynamics (landslides, erosion, flooding, or phenology) in high spectral and spatial resolution.

LLNL/Lion Precision LVDT amplifier

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hopkins, D.J.

1994-04-01

A high-precision, low-noise, LVDT amplifier has been developed which is a significant advancement on the current state of the art in contact displacement measurement. This amplifier offers the dynamic range of a typical LVDT probe but with a resolution that rivals that of non contact displacement measuring systems such as capacitance gauges and laser interferometers. Resolution of 0.1 {mu} in with 100 Hz bandwidth is possible. This level of resolution is over an order of magnitude greater than what is now commercially available. A front panel switch can reduce the bandwidth to 2.5 Hz and attain a resolution of 0.025more » {mu} in. This level of resolution meets or exceeds that of displacement measuring laser interferometry or capacitance gauge systems. Contact displacement measurement offers high part spatial resolution and therefore can measure not only part contour but surface finish. Capacitance gauges and displacement laser interferometry offer poor part spatial resolution and can not provide good surface finish measurements. Machine tool builders, meteorologists and quality inspection departments can immediately utilize the higher accuracy and capabilities that this amplifier offers. The precision manufacturing industry can improve as a result of improved capability to measure parts that help reduce costs and minimize material waste.« less

Dual wavelength laser diode excitation source for 2D photoacoustic imaging.

NASA Astrophysics Data System (ADS)

Allen, Thomas J.; Beard, Paul C.

2007-02-01

Photoacoustic methods can be used to make spatially resolved spectroscopic measurements of blood oxygenation when using a multiwavelength excitation source, such as an OPO system. Since these excitation sources are usually expensive and bulky, an alternative is to use laser diodes. A fibre coupled laser diode excitation system has been developed, providing two wavelengths, 850 and 905nm, each composed of 6 high peak power pulsed laser diodes. The system provided variable pulse durations (65-500ns) and repetition rates of up to 5KHz. The pulse energies delivered by the excitation system at 905nm and 850nm were measured to be 120μJ and 80μJ respectively for a 200ns pulse duration. To demonstrate the utility of the system, the excitation source was combined with an ultrasound detector to form a probe for in vivo single point measurements of superficial blood vessels. Changes in blood oxygenation and volume in the finger tip were monitored while making venous and arterial occlusions. To demonstrate the imaging capability of the excitation system, 2D photoacoustic images of a physiologically realistic phantom were obtained for a range of pulse durations using a cylindrical scanning system. The phantom was composed of cylindrical absorbing elements (μa=1mm^{-1}) of 2.7mm diameter, immersed in a 1% intralipid solution (μs=1mm^{-1}). This study demonstrated the potential use of laser diodes as an excitation source for photoacoustic imaging of superficial vascular structures.

Scanning mid-IR laser apparatus with eye tracking for refractive surgery

NASA Astrophysics Data System (ADS)

Telfair, William B.; Yoder, Paul R., Jr.; Bekker, Carsten; Hoffman, Hanna J.; Jensen, Eric F.

1999-06-01

A robust, real-time, dynamic eye tracker has been integrated with the short pulse mid-infrared laser scanning delivery system previously described. This system employs a Q- switched Nd:YAG laser pumped optical parametric oscillator operating at 2.94 micrometers. Previous ablation studies on human cadaver eyes and in-vivo cat eyes demonstrated very smooth ablations with extremely low damage levels similar to results with an excimer. A 4-month healing study with cats indicated no adverse healing effects. In order to treat human eyes, the tracker is required because the eyes move during the procedure due to both voluntary and involuntary motions such as breathing, heartbeat, drift, loss of fixation, saccades and microsaccades. Eye tracking techniques from the literature were compared. A limbus tracking system was best for this application. Temporal and spectral filtering techniques were implemented to reduce tracking errors, reject stray light, and increase signal to noise ratio. The expanded-capability system (IRVision AccuScan 2000 Laser System) has been tested in the lab on simulated eye targets, glass eyes, cadaver eyes, and live human subjects. Circular targets ranging from 10-mm to 14-mm diameter were successfully tracked. The tracker performed beyond expectations while the system performed myopic photorefractive keratectomy procedures on several legally blind human subjects.

Ex vivo evaluation of super pulse diode laser system with smart temperature feedback for contact soft-tissue surgery

NASA Astrophysics Data System (ADS)

Yaroslavsky, Ilya; Boutoussov, Dmitri; Vybornov, Alexander; Perchuk, Igor; Meleshkevich, Val; Altshuler, Gregory

2018-02-01

Until recently, Laser Diodes (LD) have been limited in their ability to deliver high peak power levels, which, in turn, limited their clinical capabilities. New technological developments made possible advent of "super pulse" LD (SPLD). Moreover, advanced means of smart thermal feedback enable precise control of laser power, thus ensuring safe and optimally efficacious application. In this work, we have evaluated a prototype SPLD system ex vivo. The device provided up to 25 W average and up to 150 W pulse power at 940 nm wavelength. The laser was operated in the thermal feedback-controlled mode, where power of the laser was varied automatically as a function of real-time thermal feedback to maintain constant tip temperature. The system was also equipped with a fiber tip initiated with advanced TiO2 /tungsten technique. Evaluation methods were designed to assess: 1) Speed and depth of cutting; 2) Dimensions of coagulative margin. The SPLD system was compared with industry-leading conventional diode and CO2 devices. The results indicate that the SPLD system provides increase in speed of controlled cutting by a factor of >2 in comparison with the conventional diode laser and approaching that of CO2 device. The produced ratio of the depth of cut to the thermal damage margin was significantly higher than conventional diodes and close to that of the CO2 system, suggesting optimal hemostasis conditions. SPLD technology with real-time temperature control has a potential for creating a new standard of care in the field of precision soft tissue surgery.

Portable standoff Raman system for fast detection of homemade explosives through glass, plastic, and water

NASA Astrophysics Data System (ADS)

Misra, Anupam K.; Sharma, Shiv K.; Acosta, Tayro E.; Porter, John N.; Lucey, Paul G.; Bates, David E.

2012-06-01

The University of Hawaii has been developing portable remote Raman systems capable of detecting chemicals in daylight from a safe standoff distance. We present data on standoff detection of chemicals used in the synthesis of homemade explosives (HME) using a portable standoff Raman system utilizing an 8-inch telescope. Data show that good-quality Raman spectra of various hazardous chemicals such as ammonium nitrate, potassium nitrate, potassium perchlorate, sulfur, nitrobenzene, benzene, acetone, various organic and inorganic chemicals etc. could be easily obtained from remote distances, tested up to 120 meters, with a single-pulse laser excitation and with detection time less than 1 μs. The system uses a frequency-doubled Nd:YAG pulsed laser source (532 nm, 100 mJ/pulse, 15 Hz, pulse width 10 ns) capable of firing a single or double pulse. The double-pulse configuration also allows the system to perform standoff LIBS (Laser-Induced Breakdown Spectroscopy) at 50 m range. In the standoff Raman detection, the doublepulse sequence simply doubles the signal to noise ratio. Significant improvement in the quality of Raman spectra is observed when the standoff detection is made with 1s integration time. The system uses a 50-micron slit and has spectral resolution of 8 cm-1. The HME chemicals could be easily detected through clear and brown glass bottles, PP and HDPE plastic bottles, and also through fluorescent plastic water bottles. Standoff Raman detection of HME chemical from a 10 m distance through non-visible concealed bottles in plastic bubble wrap packaging is demonstrated with 1 s integration time. Possible applications of the standoff Raman system for homeland security and environmental monitoring are discussed.

Free space optical communication based on pulsed lasers

NASA Astrophysics Data System (ADS)

Drozd, Tadeusz; Mierczyk, Zygmunt; Zygmunt, Marek; Wojtanowski, Jacek

2016-12-01

Most of the current optical data transmission systems are based on continuous wave (cw) lasers. It results from the tendency to increase data transmission speed, and from the simplicity in implementation (straightforward modulation). Pulsed lasers, which find many applications in a variety of industrial, medical and military systems, in this field are not common. Depending on the type, pulsed lasers can generate instantaneous power which is many times greater when compared with cw lasers. As such, they seem to be very attractive to be used in data transmission technology, especially due to the potentially larger ranges of transmission, or in adverse atmospheric conditions where low power cw-lasersbased transmission is no longer feasible. It is also a very practical idea to implement data transmission capability in the pulsed laser devices that have been around and already used, increasing the functionality of this type of equipment. At the Institute of Optoelectronics at Military University of Technology, a unique method of data transmission based on pulsed laser radiation has been developed. This method is discussed in the paper in terms of both data transmission speed and transmission range. Additionally, in order to verify the theoretical assumptions, modules for voice and data transmission were developed and practically tested which is also reported, including the measurements of Bit Error Rate (BER) and performance vs. range analysis.

Realtime photoacoustic microscopy in vivo with a 30-MHz ultrasound array transducer.

PubMed

Zemp, Roger J; Song, Liang; Bitton, Rachel; Shung, K Kirk; Wang, Lihong V

2008-05-26

We present a novel high-frequency photoacoustic microscopy system capable of imaging the microvasculature of living subjects in realtime to depths of a few mm. The system consists of a high-repetition-rate Q-switched pump laser, a tunable dye laser, a 30-MHz linear ultrasound array transducer, a multichannel high-frequency data acquisition system, and a shared-RAM multi-core-processor computer. Data acquisition, beamforming, scan conversion, and display are implemented in realtime at 50 frames per second. Clearly resolvable images of 6-microm-diameter carbon fibers are experimentally demonstrated at 80 microm separation distances. Realtime imaging performance is demonstrated on phantoms and in vivo with absorbing structures identified to depths of 2.5-3 mm. This work represents the first high-frequency realtime photoacoustic imaging system to our knowledge.

Laser Machining of Melt Infiltrated Ceramic Matrix Composite

NASA Technical Reports Server (NTRS)

Jarmon, D. C.; Ojard, G.; Brewer, D.

2012-01-01

As interest grows in considering the use of ceramic matrix composites for critical components, the effects of different machining techniques, and the resulting machined surfaces, on strength need to be understood. This work presents the characterization of a Melt Infiltrated SiC/SiC composite material system machined by different methods. While a range of machining approaches were initially considered, only diamond grinding and laser machining were investigated on a series of tensile coupons. The coupons were tested for residual tensile strength, after a stressed steam exposure cycle. The data clearly differentiated the laser machined coupons as having better capability for the samples tested. These results, along with micro-structural characterization, will be presented.

Multimodal fiber source for nonlinear microscopy based on a dissipative soliton laser

PubMed Central

Lamb, Erin S.; Wise, Frank W.

2015-01-01

Recent developments in high energy femtosecond fiber lasers have enabled robust and lower-cost sources for multiphoton-fluorescence and harmonic-generation imaging. However, picosecond pulses are better suited for Raman scattering microscopy, so the ideal multimodal source for nonlinear microcopy needs to provide both durations. Here we present spectral compression of a high-power femtosecond fiber laser as a route to producing transform-limited picosecond pulses. These pulses pump a fiber optical parametric oscillator to yield a robust fiber source capable of providing the synchronized picosecond pulse trains needed for Raman scattering microscopy. Thus, this system can be used as a multimodal platform for nonlinear microscopy techniques. PMID:26417497

Antares alignment gimbal positioner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Day, R.D.; Viswanathan, V.K.; Saxman, A.C.

1981-01-01

Antares is a 24-beam 40-TW carbon-dioxide (CO/sub 2/) laser fusion system currently under construction at the Los Alamos National Laboratory. The Antares alignment gimbal positioner (AGP) is an optomechanical instrument that will be used for target alignment and alignment of the 24 laser beams, as well as beam quality assessments. The AGP will be capable of providing pointing, focusing, and wavefront optical path difference, as well as aberration information at both helium-neon (He-Ne) and CO/sub 2/ wavelengths. It is designed to allow the laser beams to be aligned to any position within a 1-cm cube to a tolerance of 10more » ..mu..m.« less

Comprehensive study of solid pharmaceutical tablets in visible, near infrared (NIR), and longwave infrared (LWIR) spectral regions using a rapid simultaneous ultraviolet/visible/NIR (UVN) + LWIR laser-induced breakdown spectroscopy linear arrays detection system and a fast acousto-optic tunable filter NIR spectrometer.

PubMed

Yang, Clayton S C; Jin, Feng; Swaminathan, Siva R; Patel, Sita; Ramer, Evan D; Trivedi, Sudhir B; Brown, Ei E; Hommerich, Uwe; Samuels, Alan C

2017-10-30

This is the first report of a simultaneous ultraviolet/visible/NIR and longwave infrared laser-induced breakdown spectroscopy (UVN + LWIR LIBS) measurement. In our attempt to study the feasibility of combining the newly developed rapid LWIR LIBS linear array detection system to existing rapid analytical techniques for a wide range of chemical analysis applications, two different solid pharmaceutical tablets, Tylenol arthritis pain and Bufferin, were studied using both a recently designed simultaneous UVN + LWIR LIBS detection system and a fast AOTF NIR (1200 to 2200 nm) spectrometer. Every simultaneous UVN + LWIR LIBS emission spectrum in this work was initiated by one single laser pulse-induced micro-plasma in the ambient air atmosphere. Distinct atomic and molecular LIBS emission signatures of the target compounds measured simultaneously in UVN (200 to 1100 nm) and LWIR (5.6 to 10 µm) spectral regions are readily detected and identified without the need to employ complex data processing. In depth profiling studies of these two pharmaceutical tablets without any sample preparation, one can easily monitor the transition of the dominant LWIR emission signatures from coating ingredients gradually to the pharmaceutical ingredients underneath the coating. The observed LWIR LIBS emission signatures provide complementary molecular information to the UVN LIBS signatures, thus adding robustness to identification procedures. LIBS techniques are more surface specific while NIR spectroscopy has the capability to probe more bulk materials with its greater penetration depth. Both UVN + LWIR LIBS and NIR absorption spectroscopy have shown the capabilities of acquiring useful target analyte spectral signatures in comparable short time scales. The addition of a rapid LWIR spectroscopic probe to these widely used optical analytical methods, such as NIR spectroscopy and UVN LIBS, may greatly enhance the capability and accuracy of the combined system for a comprehensive analysis.

Biological Effects of Laser Radiation. Volume II. Review of Our Studies on Biological Effects of Laser Radiation-1965-1971.

DTIC Science & Technology

1978-10-17

alter the immunological capability/virulence ratio of influenza virus ; gross and microscopic descriptions of lesions, their natural history, and...with Viruses 4 Chapter 4 Studies on Normal Animals 6 Chapter 5 Tumor-Related Laser Radiation Studies and Potential for Carcinogenesis 17 Chapter 6...affect the immunological capability/virulence ratio of influenza virus in order to explore facilitation of vaccine production; 5) extensive gross and

Scope of Work for Integration Management and Installation Services of the National Ignition Facility Beampath Infrastructure System

NASA Astrophysics Data System (ADS)

Coyle, P. D.

2000-03-01

The goal of the National Ignition Facility (NIF) project is to provide an above ground experimental capability for maintaining nuclear competence and weapons effects simulation and to provide a facility capable of achieving fusion ignition using solid-state lasers as the energy driver. The facility will incorporate 192 laser beams, which will be focused onto a small target located at the center of a spherical target chamber-the energy from the laser beams will be deposited in a few billionths of a second. The target will then implode, forcing atomic nuclei to sufficiently high temperatures and densities necessary to achieve a miniature fusion reaction. The NIF is under construction, at Livermore, California, located approximately 50 miles southeast of San Francisco, California. The University of California, Lawrence Livermore National Laboratory (LLNL), operating under Prime Contract W-7405-ENG. 48 with the U.S. Department of Energy (DOE), shall subcontract for Integration Management and Installation (IMI) Services for the Beampath Infrastructure System (BIS). The BIS includes Beampath Hardware and Beampath Utilities. Conventional Facilities work for the NIF Laser and Target Area Building (LTAB) and Optics Assembly Building (OAB) is over 86 percent constructed. This Scope of Work is for Integration Management and Installation (IMI) Services corresponding to Management Services, Design Integration Services, Construction Services, and Commissioning Services for the NIB BIS. The BIS includes Beampath Hardware and Beampath Utilities. Beampath Hardware and Beampath Utilities include beampath vessels, enclosures, and beam tubes; auxiliary and utility systems; and support structures. A substantial amount of GFE will be provided by the University for installation as part of the infrastructure packages.

Evaluation and design of non-lethal laser dazzlers utilizing microcontrollers

NASA Astrophysics Data System (ADS)

Richardson, Keith Jack

Current non-lethal weapons suffer from an inability to meet requirements for uses across many fields and purposes. The safety and effectiveness of these weapons are inadequate. New concepts have provided a weapon utilizing lasers to flashblind a target's visual system. Minimal research and testing have been conducted to investigate the efficiency and safety of these weapons called laser dazzlers. Essentially a laser dazzler is comprised of a laser beam that has been diverged with the use of a lens to expand the beam creating an intensely bright flashlight. All laser dazzlers to date are incapable of adjusting to external conditions automatically. This is important, because the power of these weapons need to change according to distance and light conditions. At long distances, the weapon is rendered useless because the laser beam has become diluted. At near distances, the weapon is too powerful causing permanent damage to the eye because the beam is condensed. Similarly, the eye adapts to brightness by adjusting the pupil size, which effectively limits the amount of light entering the eye. Laser eye damage is determined by the level of irradiance entering the eye. Therefore, a laser dazzler needs the ability to adjust output irradiance to compensate for the distance to the target and ambient light conditions. It was postulated if an innovative laser dazzler design could adjust the laser beam divergence then the irradiance at the eye could be optimized for maximum vision disruption with minimal risk of permanent damage. The young nature of these weapons has lead to the rushed assumptions of laser wavelengths (color) and pulsing frequencies to cause maximum disorientation. Research provided key values of irradiance, wavelength, pulsing frequency and functions for the optical lens system. In order for the laser dazzler to continuously evaluate the external conditions, luminosity and distance sensors were incorporated into the design. A control system was devised to operate the mechanical components meeting calculated values. Testing the conceptual laser dazzlers illustrated the complexities of the system. A set irradiance value could be met at any distance and light condition, although this was accomplished by less than ideal methods. The final design included two lasers and only one optical system. The optical system was only capable of providing constant irradiance of one laser or the other allowing only single laser operation. For dual laser operation, the optical system was calibrated to offset the losses of each laser as distance was changed. Ultimately, this provided a constant combined irradiance with a decreasing green irradiance and increasing red irradiance as distance was increasing. Future work should include enhancements to the mechanical components of the laser dazzler to further refine accuracy. This research was intended to provide a proof of concept and did so successfully.

Laser-to-hot-electron conversion limitations in relativistic laser matter interactions due to multi-picosecond dynamics

NASA Astrophysics Data System (ADS)

Schollmeier, M.; Sefkow, A. B.; Geissel, M.; Arefiev, A. V.; Flippo, K. A.; Gaillard, S. A.; Johnson, R. P.; Kimmel, M. W.; Offermann, D. T.; Rambo, P. K.; Schwarz, J.; Shimada, T.

2015-04-01

High-energy short-pulse lasers are pushing the limits of plasma-based particle acceleration, x-ray generation, and high-harmonic generation by creating strong electromagnetic fields at the laser focus where electrons are being accelerated to relativistic velocities. Understanding the relativistic electron dynamics is key for an accurate interpretation of measurements. We present a unified and self-consistent modeling approach in quantitative agreement with measurements and differing trends across multiple target types acquired from two separate laser systems, which differ only in their nanosecond to picosecond-scale rising edge. Insights from high-fidelity modeling of laser-plasma interaction demonstrate that the ps-scale, orders of magnitude weaker rising edge of the main pulse measurably alters target evolution and relativistic electron generation compared to idealized pulse shapes. This can lead for instance to the experimentally observed difference between 45 MeV and 75 MeV maximum energy protons for two nominally identical laser shots, due to ps-scale prepulse variations. Our results show that the realistic inclusion of temporal laser pulse profiles in modeling efforts is required if predictive capability and extrapolation are sought for future target and laser designs or for other relativistic laser ion acceleration schemes.

Fast and broadband detector for laser radiation

NASA Astrophysics Data System (ADS)

Scorticati, Davide; Crapella, Giacomo; Pellegrino, Sergio

2018-02-01

We developed a fast detector (patent pending) based on the Laser Induced Transverse Voltage (LITV) effect. The advantage of detectors using the LITV effect over pyroelectric sensors and photodiodes for laser radiation measurements is the combination of an overall fast response time, broadband spectral acceptance, high saturation threshold to direct laser irradiation and the possibility to measure pulsed as well as cw-laser sources. The detector is capable of measuring the energy of single laser pulses with repetition frequencies up to the MHz range, adding the possibility to also measure the output power of cw-lasers. Moreover, the thermal nature of the sensor enables the capability to work in a broadband spectrum, from UV to THz as well as the possibility of operating in a broad-range (10-3-102 W/cm2 ) of incident average optical power densities of the laser radiation, without the need of adopting optical filters nor other precautions.