Safety and Hazard Analysis for the Coherent/Acculite Laser Based Sandia Remote Sensing System (Trailer B70).

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

Augustoni, Arnold L.

A laser safety and hazard analysis is presented, for the Coherent(r) driven Acculite(r) laser central to the Sandia Remote Sensing System (SRSS). The analysis is based on the 2000 version of the American National Standards Institute's (ANSI) Standard Z136.1, for Safe Use of Lasers and the 2000 version of the ANSI Standard Z136.6, for Safe Use of Lasers Outdoors. The trailer (B70) based SRSS laser system is a mobile platform which is used to perform laser interaction experiments and tests at various national test sites. The trailer based SRSS laser system is generally operated on the United State Air Forcemore » Starfire Optical Range (SOR) at Kirtland Air Force Base (KAFB), New Mexico. The laser is used to perform laser interaction testing inside the laser trailer as well as outside the trailer at target sites located at various distances. In order to protect personnel who work inside the Nominal Hazard Zone (NHZ) from hazardous laser exposures, it was necessary to determine the Maximum Permissible Exposure (MPE) for each laser wavelength (wavelength bands) and calculate the appropriate minimum Optical Density (ODmin) necessary for the laser safety eyewear used by authorized personnel. Also, the Nominal Ocular Hazard Distance (NOHD) and The Extended Ocular Hazard Distance (EOHD) are calculated in order to protect unauthorized personnel who may have violated the boundaries of the control area and might enter into the laser's NHZ for testing outside the trailer. 4Page intentionally left blank« less

Key techniques for space-based solar pumped semiconductor lasers

NASA Astrophysics Data System (ADS)

He, Yang; Xiong, Sheng-jun; Liu, Xiao-long; Han, Wei-hua

2014-12-01

In space, the absence of atmospheric turbulence, absorption, dispersion and aerosol factors on laser transmission. Therefore, space-based laser has important values in satellite communication, satellite attitude controlling, space debris clearing, and long distance energy transmission, etc. On the other hand, solar energy is a kind of clean and renewable resources, the average intensity of solar irradiation on the earth is 1353W/m2, and it is even higher in space. Therefore, the space-based solar pumped lasers has attracted much research in recent years, most research focuses on solar pumped solid state lasers and solar pumped fiber lasers. The two lasing principle is based on stimulated emission of the rare earth ions such as Nd, Yb, Cr. The rare earth ions absorb light only in narrow bands. This leads to inefficient absorption of the broad-band solar spectrum, and increases the system heating load, which make the system solar to laser power conversion efficiency very low. As a solar pumped semiconductor lasers could absorb all photons with energy greater than the bandgap. Thus, solar pumped semiconductor lasers could have considerably higher efficiencies than other solar pumped lasers. Besides, solar pumped semiconductor lasers has smaller volume chip, simpler structure and better heat dissipation, it can be mounted on a small satellite platform, can compose satellite array, which can greatly improve the output power of the system, and have flexible character. This paper summarizes the research progress of space-based solar pumped semiconductor lasers, analyses of the key technologies based on several application areas, including the processing of semiconductor chip, the design of small and efficient solar condenser, and the cooling system of lasers, etc. We conclude that the solar pumped vertical cavity surface-emitting semiconductor lasers will have a wide application prospects in the space.

The Geoscience Laser Altimeter System (GLAS) Laser Transmitter

NASA Technical Reports Server (NTRS)

Afzal, Robert S.; Yu, Anthony W.; Dallas, Joseph L.; Melak, Anthony; Lukemir, Alan; Ramos-Izqueirdo, L.; Mamakos, William

2007-01-01

The Geoscience Laser Altimeter System (GLAS), launched in January 2003, is a laser altimeter and lidar for the Earth Observing System's (EOS) ICESat mission. GLAS accommodates three, sequentially operated, diode-pumped, solid-state, Nd:YAG laser transmitters. The laser transmitter requirements, design and qualification test results for this space-based remote sensing instrument is summarized and presented

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.

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

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 Spot Detection Based on Reaction Diffusion.

PubMed

Vázquez-Otero, Alejandro; Khikhlukha, Danila; Solano-Altamirano, J M; Dormido, Raquel; Duro, Natividad

2016-03-01

Center-location of a laser spot is a problem of interest when the laser is used for processing and performing measurements. Measurement quality depends on correctly determining the location of the laser spot. Hence, improving and proposing algorithms for the correct location of the spots are fundamental issues in laser-based measurements. In this paper we introduce a Reaction Diffusion (RD) system as the main computational framework for robustly finding laser spot centers. The method presented is compared with a conventional approach for locating laser spots, and the experimental results indicate that RD-based computation generates reliable and precise solutions. These results confirm the flexibility of the new computational paradigm based on RD systems for addressing problems that can be reduced to a set of geometric operations.

Solid-state-based laser system as a replacement for Ar⁺ lasers.

PubMed

Beck, Tobias; Rein, Benjamin; Sörensen, Fabian; Walther, Thomas

2016-09-15

We report on a solid-state-based laser system at 1028 nm. The light is generated by a diode laser seeded ytterbium fiber amplifier. In two build-up cavities, its frequency is doubled and quadrupled to 514 nm and 257 nm, respectively. At 514 nm, the system delivers up to 4.7 W of optical power. In the fourth harmonic, up to 173 mW are available limited by the nonlinear crystal. The frequency of the laser is mode-hop-free tunable by 16 GHz in 10 ms in the UV. Therefore, the system is suitable as a low maintenance, efficient, and tunable narrowband replacement for frequency doubled Ar⁺ laser systems.

Differential correction system of laser beam directional dithering based on symmetrical beamsplitter

NASA Astrophysics Data System (ADS)

Hongwei, Yang; Wei, Tao; Xiaoqia, Yin; Hui, Zhao

2018-02-01

This paper proposes a differential correction system with a differential optical path and a symmetrical beamsplitter for correcting the directional dithering of the laser beams. This system can split a collimated laser beam into two laser beams with equal and opposite movements. Thus, the positional averages of the two split laser beams remain constant irrespective of the dithering angle. The symmetrical beamsplitter designed based on transfer matrix principle is to balance the optical paths and irradiances of the two laser beams. Experimental results show that the directional dithering is reduced to less than one-pixel value. Finally, two examples show that this system can be widely used in one-dimensional measurement.

The study of laser beam riding guided system based on 980nm diode laser

NASA Astrophysics Data System (ADS)

Qu, Zhou; Xu, Haifeng; Sui, Xin; Yang, Kun

2015-10-01

With the development of science and technology, precision-strike weapons has been considered to be important for winning victory in military field. Laser guidance is a major method to execute precision-strike in modern warfare. At present, the problems of primary stage of Laser guidance has been solved with endeavors of countries. Several technical aspects of laser-beam riding guided system have been mature, such as atmosphere penetration of laser beam, clutter inhibition on ground, laser irradiator, encoding and decoding of laser beam. Further, laser beam quality, equal output power and atmospheric transmission properties are qualified for warfare situation. Riding guidance instrument is a crucial element of Laser-beam riding guided system, and is also a vital element of airborne, vehicle-mounted and individual weapon. The optical system mainly consist of sighting module and laser-beam guided module. Photoelectric detector is the most important sensing device of seeker, and also the key to acquire the coordinate information of target space. Currently, in consideration of the 1.06 u m of wavelength applied in all the semi-active laser guided weapons systems, lithium drifting silicon photodiode which is sensitive to 1.06 u m of wavelength is used in photoelectric detector. Compared to Solid and gas laser, diode laser has many merits such as small volume, simple construction, light weight, long life, low lost and easy modulation. This article introduced the composition and operating principle of Laser-beam riding guided system based on 980 nm diode laser, and made a analysis of key technology; for instance, laser irradiator, modulating disk of component, laser zooming system. Through the use of laser diode, Laser-beam riding guided system is likely to have smaller shape and very light.

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.

Large-Scale Production of Carbon Nanotubes Using the Jefferson Lab Free Electron Laser

NASA Technical Reports Server (NTRS)

Holloway, Brian C.

2003-01-01

We report on our interdisciplinary program to use the Free Electron Laser (FEL) at the Thomas Jefferson National Accelerator Facility (J-Lab) for high-volume pulsed laser vaporization synthesis of carbon nanotubes. Based in part on the funding of from this project, a novel nanotube production system was designed, tested, and patented. Using this new system nanotube production rates over 100 times faster than conventional laser systems were achieved. Analysis of the material produced shows that it is of as high a quality as the standard laser-based materials.

SU-E-T-99: Design and Development of Isocenter Parameter System for CT Simulation Laser Based On DICOM RT

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

Luo, G

2014-06-01

Purpose: In order to receive DICOM files from treatment planning system and generate patient isocenter positioning parameter file for CT laser system automatically, this paper presents a method for communication with treatment planning system and calculation of isocenter parameter for each radiation field. Methods: Coordinate transformation and laser positioning file formats were analyzed, isocenter parameter was calculated via data from DICOM CT Data and DICOM RTPLAN file. An in-house software-DicomGenie was developed based on the object-oriented program platform-Qt with DCMTK SDK (Germany OFFIS company DICOM SDK) . DicomGenie was tested for accuracy using Philips CT simulation plan system (Tumor LOC,more » Philips) and A2J CT positioning laser system (Thorigny Sur Marne, France). Results: DicomGenie successfully established DICOM communication between treatment planning system, DICOM files were received by DicomGenie and patient laser isocenter information was generated accurately. Patient laser parameter data files can be used for for CT laser system directly. Conclusion: In-house software DicomGenie received and extracted DICOM data, isocenter laser positioning data files were created by DicomGenie and can be use for A2J laser positioning system.« less

Dual-beam laser autofocusing system based on liquid lens

NASA Astrophysics Data System (ADS)

Zhang, Fumin; Yao, Yannan; Qu, Xinghua; Zhang, Tong; Pei, Bing

2017-02-01

A dual-beam laser autofocusing system is designed in this paper. The autofocusing system is based on a liquid lens with less moving parts and fast response time, which makes the system simple, reliable, compact and fast. A novel scheme ;Time-sharing focus, fast conversion; is innovatively proposed. The scheme effectively solves the problem that the guiding laser and the working laser cannot focus at the same target point because of the existence of chromatic aberration. This scheme not only makes both guiding laser and working laser achieve optimal focusing in guiding stage and working stage respectively, but also greatly reduces the system complexity and simplifies the focusing process as well as makes autofocusing time of the working laser reduce to about 10 ms. In the distance range of 1 m to 30 m, the autofocusing spot size is kept under 4.3 mm at 30 m and just 0.18 mm at 1 m. The spot size is much less influenced by the target distance compared with the collimated laser with a micro divergence angle for its self-adaptivity. The dual-beam laser autofocusing system based on liquid lens is fully automatic, compact and efficient. It is fully meet the need of dynamicity and adaptivity and it will play an important role in a number of long-range control applications.

Improved pulse laser ranging algorithm based on high speed sampling

NASA Astrophysics Data System (ADS)

Gao, Xuan-yi; Qian, Rui-hai; Zhang, Yan-mei; Li, Huan; Guo, Hai-chao; He, Shi-jie; Guo, Xiao-kang

2016-10-01

Narrow pulse laser ranging achieves long-range target detection using laser pulse with low divergent beams. Pulse laser ranging is widely used in military, industrial, civil, engineering and transportation field. In this paper, an improved narrow pulse laser ranging algorithm is studied based on the high speed sampling. Firstly, theoretical simulation models have been built and analyzed including the laser emission and pulse laser ranging algorithm. An improved pulse ranging algorithm is developed. This new algorithm combines the matched filter algorithm and the constant fraction discrimination (CFD) algorithm. After the algorithm simulation, a laser ranging hardware system is set up to implement the improved algorithm. The laser ranging hardware system includes a laser diode, a laser detector and a high sample rate data logging circuit. Subsequently, using Verilog HDL language, the improved algorithm is implemented in the FPGA chip based on fusion of the matched filter algorithm and the CFD algorithm. Finally, the laser ranging experiment is carried out to test the improved algorithm ranging performance comparing to the matched filter algorithm and the CFD algorithm using the laser ranging hardware system. The test analysis result demonstrates that the laser ranging hardware system realized the high speed processing and high speed sampling data transmission. The algorithm analysis result presents that the improved algorithm achieves 0.3m distance ranging precision. The improved algorithm analysis result meets the expected effect, which is consistent with the theoretical simulation.

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.

TIL system with nonlinear phase conjugation

NASA Astrophysics Data System (ADS)

Khizhnyak, Anatoliy; Markov, Vladimir

2007-09-01

Efficient laser beam delivery on a distant target remains a key problem for practical implementation of tactical laser systems. Since the conventional target-in-the-loop (TIL) concept is generally not effective in such operational environments, new solutions are needed. In this report we discuss an innovative approach for effective compensation of laser beam aberrations in TIL systems. It is based on a recently devised technique that combines optical phase conjugation (OPC) with a TIL system for effective hot-spot formation. The proposed method should enable delivery of enhanced density laser energy to a target within a finite number of iteration cycles. Using the model based on an analogy between the TIL system and laser resonator, pointing of the laser beam on the target is performed at the image plane, resulting in reduced hot-spot formation time.

Critical side channel effects in random bit generation with multiple semiconductor lasers in a polarization-based quantum key distribution system.

PubMed

Ko, Heasin; Choi, Byung-Seok; Choe, Joong-Seon; Kim, Kap-Joong; Kim, Jong-Hoi; Youn, Chun Ju

2017-08-21

Most polarization-based BB84 quantum key distribution (QKD) systems utilize multiple lasers to generate one of four polarization quantum states randomly. However, random bit generation with multiple lasers can potentially open critical side channels that significantly endangers the security of QKD systems. In this paper, we show unnoticed side channels of temporal disparity and intensity fluctuation, which possibly exist in the operation of multiple semiconductor laser diodes. Experimental results show that the side channels can enormously degrade security performance of QKD systems. An important system issue for the improvement of quantum bit error rate (QBER) related with laser driving condition is further addressed with experimental results.

Laser Remediation of Threats Posed by Small Orbital Debris

NASA Technical Reports Server (NTRS)

Fork, Richard L.; Rogers, Jan R.; Hovater, Mary A.

2012-01-01

The continually increasing amount of orbital debris in near Earth space poses an increasing challenge to space situational awareness. Recent collisions of spacecraft caused abrupt increases in the density of both large and small debris in near Earth space. An especially challenging class of threats is that due to the increasing density of small (1 mm to 10 cm dimension) orbital debris. This small debris poses a serious threat since: (1) The high velocity enables even millimeter dimension debris to cause serious damage to vulnerable areas of space assets, e.g., detector windows; (2) The small size and large number of debris elements prevent adequate detection and cataloguing. We have identified solutions to this threat in the form of novel laser systems and novel ways of using these laser systems. While implementation of the solutions we identify is challenging we find approaches offering threat mitigation within time frames and at costs of practical interest. We base our analysis on the unique combination of coherent light specifically structured in both space and time and applied in novel ways entirely within the vacuum of space to deorbiting small debris. We compare and contrast laser based small debris removal strategies using ground based laser systems with strategies using space based laser systems. We find laser systems located and used entirely within space offer essential and decisive advantages over groundbased laser systems.

Evaluation of OH laser-induced fluorescence techniques for supersonic combustion diagnostics

NASA Technical Reports Server (NTRS)

Quagliaroli, T. M.; Laufer, G.; Krauss, R. H.; Mcdaniel, J. C., Jr.

1992-01-01

The limitations on application of dye laser and narrowband tunable KrF excimer laser systems to planar OH fluorescence measurements in supersonic combustion test facilities are examined. Included in the analysis are effects of collisional quenching, beam absorption, fluorescence trapping, and signal strengths on achievable measurement accuracy using several excitation and detection options for either of the two laser systems. Dye-based laser systems are found to be the method of choice for imaging OH concentrations less than 10 exp 15 per cu cm, while the KrF based systems provide significant reduction in measurement ambiguity for concentrations in excess of 10 exp 15 per cu cm.

The design and implementation of photoacoustic based laser warning receiver for harsh environments

NASA Astrophysics Data System (ADS)

El-Sherif, Ashraf F.; Ayoub, H. S.; El-Sharkawy, Yasser H.; Gomaa, Walid; Hassan, H. H.

2018-01-01

This paper discusses the implementation of new type of laser warning receiver (LWR) system, based on the detection of photoacoustic signals, induced by high power infrared laser designators pulses on target's surfaces. This system appends conventional optoelectronic based LWR to decrease the false alarm rate (FAR) in harsh environments, where ambient conditions are expected to obstruct optical LWR. To improve the sensitivity of the photoacoustic based LWR system, some metallic and polymeric target shielding materials were studied, in order to cover a friendly civil structure, vehicle or a maritime entity with a low cost large area acoustic detector array shield. A thermographic investigation of target surface material- laser reaction, signal processing and system configuration and functional analysis are also presented.

Optically-Based Diagnostics for Gas-Phase Laser Development

DTIC Science & Technology

2010-08-01

Laser (COIL), Electric Oxygen Iodine Laser (EOIL), Diode-Pumped Alkali Laser (DPAL), and Exciplex Alkali Laser (XPAL). The papers at this Symposium... exciplex -assisted absorption and laser-induced fluorescence, and multi-photon excitation of infrared atomic alkali transitions.11,12 In this paper... EXCIPLEX LASER SYSTEMS Proper review and discussion of the DPAL and XPAL laser systems can be found elsewhere,11,12 and in the paper by Carroll and

Sensor-based laser ablation for tissue specific cutting: an experimental study.

PubMed

Rupprecht, Stephan; Tangermann-Gerk, Katja; Wiltfang, Joerg; Neukam, Friedrich Wilhelm; Schlegel, Andreas

2004-01-01

The interaction of laser light and tissue causes measurable phenomenons. These phenomenons can be quantified and used to control the laser drilling within a feedback system. Ten halves of dissected minipig jaws were treated with an Er:YAG laser system controlled via a feedback system. Sensor outputs were recorded and analyzed while osteotomy was done. The relative depth of laser ablation was calculated by 3D computed tomography and evaluated histologically. The detected signals caused by the laser-tissue interaction changed their character in a dramatic way after passing the cortical bone layer. The radiological evaluation of 98 laser-ablated holes in the ten halves showed no deeper ablation beyond the cortical layer (mean values: 97.8%). Histologically, no physical damage to the alveolar nerve bundle was proved. The feedback system to control the laser drilling was working exactly for cortical ablation of the bone based on the evaluation of detected and quantified phenomenon related to the laser-tissue interaction.

Efficient Third Harmonic Generation for Wind Lidar Applications

NASA Technical Reports Server (NTRS)

Mordaunt, David W.; Cheung, Eric C.; Ho, James G.; Palese, Stephen P.

1998-01-01

The characterization of atmospheric winds on a global basis is a key parameter required for accurate weather prediction. The use of a space based lidar system for remote measurement of wind speed would provide detailed and highly accurate data for future weather prediction models. This paper reports the demonstration of efficient third harmonic conversion of a 1 micrometer laser to provide an ultraviolet (UV) source suitable for a wind lidar system based on atmospheric molecular scattering. Although infrared based lidars using aerosol scattering have been demonstrated to provide accurate wind measurement, a UV based system using molecular or Rayleigh scattering will provide accurate global wind measurements, even in those areas of the atmosphere where the aerosol density is too low to yield good infrared backscatter signals. The overall objective of this work is to demonstrate the maturity of the laser technology and its suitability for a near term flight aboard the space shuttle. The laser source is based on diode-pumped solid-state laser technology which has been extensively demonstrated at TRW in a variety of programs and internal development efforts. The pump laser used for the third harmonic demonstration is a breadboard system, designated the Laser for Risk Reduction Experiments (LARRE), which has been operating regularly for over 5 years. The laser technology has been further refined in an engineering model designated as the Compact Advanced Pulsed Solid-State Laser (CAPSSL), in which the laser head was packaged into an 8 x 8 x 18 inch volume with a weight of approximately 61 pounds. The CAPSSL system is a ruggedized configuration suitable for typical military applications. The LARRE and CAPSSL systems are based on Nd:YAG with an output wavelength of 1064 nm. The current work proves the viability of converting the Nd:YAG fundamental to the third harmonic wavelength at 355 nm for use in a direct detection wind lidar based on atmospheric Rayleigh scattering.

Novel diode-based laser system for combined transcutaneous monitoring and computer-controlled intermittent treatment of jaundiced neonates

NASA Astrophysics Data System (ADS)

Hamza, Mostafa; El-Ahl, Mohammad H. S.; Hamza, Ahmad M.

2001-06-01

The high efficacy of laser phototherapy combined with transcutaneous monitoring of serum bilirubin provides optimum safety for jaundiced infants from the risk of bilirubin encephalopathy. In this paper the authors introduce the design and operating principles of a new laser system that can provide simultaneous monitoring and treatment of several jaundiced babies at one time. The new system incorporates diode-based laser sources oscillating at selected wavelengths to achieve both transcutaneous differential absorption measurements of bilirubin concentration in addition to the computer controlled intermittent laser therapy through a network of optical fibers. The detailed description and operating characteristics of this system are presented.

Note: Reliable and non-contact 6D motion tracking system based on 2D laser scanners for cargo transportation.

PubMed

Kim, Young-Keun; Kim, Kyung-Soo

2014-10-01

Maritime transportation demands an accurate measurement system to track the motion of oscillating container boxes in real time. However, it is a challenge to design a sensor system that can provide both reliable and non-contact methods of 6-DOF motion measurements of a remote object for outdoor applications. In the paper, a sensor system based on two 2D laser scanners is proposed for detecting the relative 6-DOF motion of a crane load in real time. Even without implementing a camera, the proposed system can detect the motion of a remote object using four laser beam points. Because it is a laser-based sensor, the system is expected to be highly robust to sea weather conditions.

Note: Reliable and non-contact 6D motion tracking system based on 2D laser scanners for cargo transportation

NASA Astrophysics Data System (ADS)

Kim, Young-Keun; Kim, Kyung-Soo

2014-10-01

Maritime transportation demands an accurate measurement system to track the motion of oscillating container boxes in real time. However, it is a challenge to design a sensor system that can provide both reliable and non-contact methods of 6-DOF motion measurements of a remote object for outdoor applications. In the paper, a sensor system based on two 2D laser scanners is proposed for detecting the relative 6-DOF motion of a crane load in real time. Even without implementing a camera, the proposed system can detect the motion of a remote object using four laser beam points. Because it is a laser-based sensor, the system is expected to be highly robust to sea weather conditions.

New developments in laser-based photoemission spectroscopy and its scientific applications: a key issues review

NASA Astrophysics Data System (ADS)

Zhou, Xingjiang; He, Shaolong; Liu, Guodong; Zhao, Lin; Yu, Li; Zhang, Wentao

2018-06-01

The significant progress in angle-resolved photoemission spectroscopy (ARPES) in last three decades has elevated it from a traditional band mapping tool to a precise probe of many-body interactions and dynamics of quasiparticles in complex quantum systems. The recent developments of deep ultraviolet (DUV, including ultraviolet and vacuum ultraviolet) laser-based ARPES have further pushed this technique to a new level. In this paper, we review some latest developments in DUV laser-based photoemission systems, including the super-high energy and momentum resolution ARPES, the spin-resolved ARPES, the time-of-flight ARPES, and the time-resolved ARPES. We also highlight some scientific applications in the study of electronic structure in unconventional superconductors and topological materials using these state-of-the-art DUV laser-based ARPES. Finally we provide our perspectives on the future directions in the development of laser-based photoemission systems.

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.

Laser-Based Lighting: Experimental Analysis and Perspectives

PubMed Central

Yushchenko, Maksym; Buffolo, Matteo; Meneghini, Matteo; Zanoni, Enrico

2017-01-01

This paper presents an extensive analysis of the operating principles, theoretical background, advantages and limitations of laser-based lighting systems. In the first part of the paper we discuss the main advantages and issues of laser-based lighting, and present a comparison with conventional LED-lighting technology. In the second part of the paper, we present original experimental data on the stability and reliability of phosphor layers for laser lighting, based on high light-intensity and high-temperature degradation tests. In the third part of the paper (for the first time) we present a detailed comparison between three different solutions for laser lighting, based on (i) transmissive phosphor layers; (ii) a reflective/angled phosphor layer; and (iii) a parabolic reflector, by discussing the advantages and drawbacks of each approach. The results presented within this paper can be used as a guideline for the development of advanced lighting systems based on laser diodes. PMID:29019958

Perspectives of using the 223-nm wavelength of the KrCl excimer laser for refractive surgery and for the treatment of some eye diseases

NASA Astrophysics Data System (ADS)

Bagayev, Sergei N.; Chernikh, Valery V.; Razhev, Alexander M.; Zhupikov, Andrey A.

2000-06-01

The new surgical UV ophthalmic laser system Medilex based on the KrCl (223 nm) excimer laser for refractive surgery was created. The comparative analysis of using the UV ophthalmic laser systems Medilex based on the ArF (193 nm) and the KrCl (223 nm) excimer lasers for the correction of refractive errors was performed. The system with the radiation wavelength of 223 nanometer of the KrCl excimer laser for refractive surgery was shown to have several medical and technical advantages over the system with the traditionally used radiation wavelength of 193 nanometer of the ArF excimer laser. In addition the use of the wavelength of 223 nanometer extends functional features of the system, allowing to make not only standard for this type systems surgical and therapeutic procedures but also to treat such ocular diseases as the glaucoma and herpetic keratities. For the UV ophthalmic laser systems Medilex three variations of the beam delivery system including special rotating masks and different beam homogenize systems were developed. All created beam delivery systems are able to make the correction of myopia, hyperopia, astigmatism and myopic or hyperopic astigmatism and may be used for therapeutic procedures. The results of the initial treatments of refractive error corrections using the UV ophthalmic laser systems Medilex for both photorefractive keratectomy (PRK) and LASIK procedures are presented.

Laser Sources for Generation of Ultrasound

NASA Technical Reports Server (NTRS)

Wagner, James W.

1996-01-01

Two laser systems have been built and used to demonstrate enhancements beyond current technology used for laser-based generation and detection of ultrasound. The first system consisted of ten Nd:YAG laser cavities coupled electronically and optically to permit sequential bursts of up to ten laser pulses directed either at a single point or configured into a phased array of sources. Significant enhancements in overall signal-to-noise ratio for laser ultrasound incorporating this new source system was demonstrated, using it first as a source of narrowband ultrasound and secondly as a phased array source producing large enhanced signal displacements. A second laser system was implemented using ultra fast optical pulses from a Ti:Sapphire laser to study a new method for making laser generated ultrasonic measurements of thin films with thicknesses on the order of hundreds of angstroms. Work by prior investigators showed that such measurements could be made based upon fluctuations in the reflectivity of thin films when they are stressed by an arriving elastic pulse. Research performed using equipment purchased under this program showed that a pulsed interferometric system could be used as well as a piezoreflective detection system to measure pulse arrivals even in thin films with very low piezoreflective coefficients.

Optical air data systems and methods

NASA Technical Reports Server (NTRS)

Caldwell, Loren M. (Inventor); Tang, Shoou-yu (Inventor); O'Brien, Martin (Inventor)

2010-01-01

Systems and methods for sensing air outside a moving aircraft are presented. In one embodiment, a system includes a laser for generating laser energy. The system also includes one or more transceivers for projecting the laser energy as laser radiation to the air. Subsequently, each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines one or more air parameters based on the scattered laser radiation. Such air parameters may include air speed, air pressure, air temperature and aircraft orientation angle, such as yaw, angle of attack and sideslip.

Optical air data systems and methods

NASA Technical Reports Server (NTRS)

Caldwell, Loren M. (Inventor); O'Brien, Martin J. (Inventor); Weimer, Carl S. (Inventor); Nelson, Loren D. (Inventor)

2008-01-01

Systems and methods for sensing air outside a moving aircraft are presented. In one embodiment, a system includes a laser for generating laser energy. The system also includes one or more transceivers for projecting the laser energy as laser radiation to the air. Subsequently, each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines one or more air parameters based on the scattered laser radiation. Such air parameters may include air speed, air pressure, air temperature and aircraft orientation angle, such as yaw, angle of attack and sideslip.

Optical air data systems and methods

NASA Technical Reports Server (NTRS)

Caldwell, Loren M. (Inventor); O'Brien, Martin J. (Inventor); Weimer, Carl S. (Inventor); Nelson, Loren D. (Inventor)

2005-01-01

Systems and methods for sensing air outside a moving aircraft are presented. In one embodiment, a system includes a laser for generating laser energy. The system also includes one or more transceivers for projecting the laser energy as laser radiation to the air. Subsequently, each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines one or more air parameters based on the scattered laser radiation. Such air parameters may include air speed, air pressure, air temperature and aircraft orientation angle, such as yaw, angle of attack and sideslip.

Tracking Control and System Development for Laser-Driven Micro-Vehicles

NASA Astrophysics Data System (ADS)

Kajiwara, Itsuro; Hoshino, Kentaro; Hara, Shinji; Shiokata, Daisuke; Yabe, Takashi

The purpose of this paper is to design a control system for an integrated laser propulsion/tracking system to achieve continuous motion and control of laser-driven micro-vehicles. Laser propulsion is significant in achieving miniature and light micro-vehicles. A laser-driven micro-airplane has been studied using a paper airplane and YAG laser, resulting in successful gliding of the airplane. High-performance laser tracking control is required to achieve continuous flight. This paper presents a control design strategy based on the generalized Kalman-Yakubovic-Popov lemma to achieve this requirement. Experiments have been carried out to evaluate the performance of the integrated laser propulsion/tracking system.

Laser-powered MHD generators for space application

NASA Technical Reports Server (NTRS)

Jalufka, N. W.

1986-01-01

Magnetohydrodynamic (MHD) energy conversion systems of the pulsed laser-supported detonation (LSD) wave, plasma MHD, and liquid-metal MHD (LMMHD) types are assessed for their potential as space-based laser-to-electrical power converters. These systems offer several advantages as energy converters relative to the present chemical, nuclear, and solar devices, including high conversion efficiency, simple design, high-temperature operation, high power density, and high reliability. Of these systems, the Brayton cycle liquid-metal MHD system appears to be the most attractive. The LMMHD technology base is well established for terrestrial applications, particularly with regard to the generator, mixer, and other system components. However, further research is required to extend this technology base to space applications and to establish the technology required to couple the laser energy into the system most efficiently. Continued research on each of the three system types is recommended.

Detection technique of targets for missile defense system

NASA Astrophysics Data System (ADS)

Guo, Hua-ling; Deng, Jia-hao; Cai, Ke-rong

2009-11-01

Ballistic missile defense system (BMDS) is a weapon system for intercepting enemy ballistic missiles. It includes ballistic-missile warning system, target discrimination system, anti-ballistic-missile guidance systems, and command-control communication system. Infrared imaging detection and laser imaging detection are widely used in BMDS for surveillance, target detection, target tracking, and target discrimination. Based on a comprehensive review of the application of target-detection techniques in the missile defense system, including infrared focal plane arrays (IRFPA), ground-based radar detection technology, 3-dimensional imaging laser radar with a photon counting avalanche photodiode (APD) arrays and microchip laser, this paper focuses on the infrared and laser imaging detection techniques in missile defense system, as well as the trends for their future development.

Material processing with fiber based ultrafast pulse delivery

NASA Astrophysics Data System (ADS)

Baumbach, S.; Stockburger, R.; Führa, B.; Zoller, S.; Thum, S.; Moosmann, J.; Maier, D.; Kanal, F.; Russ, S.; Kaiser, E.; Budnicki, A.; Sutter, D. H.; Pricking, S.; Killi, A.

2018-02-01

We report on TRUMPF's ultrafast laser systems equipped with industrialized hollow core fiber laser light cables. Beam guidance in general by means of optical fibers, e.g. for multi kilowatt cw laser systems, has become an integral part of laser-based material processing. One advantage of fiber delivery, among others, is the mechanical separation between laser and processing head. An equally important benefit is given by the fact that the fiber end acts as an opto-mechanical fix-point close to successive optical elements in the processing head. Components like lenses, diffractive optical elements etc. can thus be designed towards higher efficiency which results in better material processing. These aspects gain increasing significance when the laser system operates in fundamental mode which is usually the case for ultrafast lasers. Through the last years beam guidance of ultrafast laser pulses by means of hollow core fiber technology established very rapidly. The combination of TRUMPF's long-term stable ultrafast laser sources, passive fiber coupling, connector and packaging forms a flexible and powerful system for laser based material processing well suited for an industrial environment. In this article we demonstrate common material processing applications with ultrafast lasers realized with TRUMPF's hollow core fiber delivery. The experimental results are contrasted and evaluated against conventional free space propagation in order to illustrate the performance of flexible ultrafast beam delivery.

Welding technology transfer task/laser based weld joint tracking system for compressor girth welds

NASA Technical Reports Server (NTRS)

Looney, Alan

1991-01-01

Sensors to control and monitor welding operations are currently being developed at Marshall Space Flight Center. The laser based weld bead profiler/torch rotation sensor was modified to provide a weld joint tracking system for compressor girth welds. The tracking system features a precision laser based vision sensor, automated two-axis machine motion, and an industrial PC controller. The system benefits are elimination of weld repairs caused by joint tracking errors which reduces manufacturing costs and increases production output, simplification of tooling, and free costly manufacturing floor space.

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.

Laser based structural health monitoring for civil, mechanical, and aerospace systems

NASA Astrophysics Data System (ADS)

Sohn, Hoon

2012-04-01

This paper provides an overview of ongoing laser ultrasonics based structural health monitoring (SHM) activities being performed by the author. Particular focus is given to (1) the development of a fully noncontact laser ultrasonic system that can easily visualize defects with high spatial resolution, (2) laser based wireless power and data transmission schemes for remote guided waves and impedance measurements, (3) minimization of false alarms due to varying operational and environmental conditions, and (4) extension to embedded laser ultrasonic excitation and sensing. SHM examples ranging from bridges to airplanes, as well as nuclear power plants, high-speed rails and wind turbines are also presented.

Test technology on divergence angle of laser range finder based on CCD imaging fusion

NASA Astrophysics Data System (ADS)

Shi, Sheng-bing; Chen, Zhen-xing; Lv, Yao

2016-09-01

Laser range finder has been equipped with all kinds of weapons, such as tank, ship, plane and so on, is important component of fire control system. Divergence angle is important performance and incarnation of horizontal resolving power for laser range finder, is necessary appraised test item in appraisal test. In this paper, based on high accuracy test on divergence angle of laser range finder, divergence angle test system is designed based on CCD imaging, divergence angle of laser range finder is acquired through fusion technology for different attenuation imaging, problem that CCD characteristic influences divergence angle test is solved.

Next generation Er:YAG fractional ablative laser

NASA Astrophysics Data System (ADS)

Heinrich, A.; Vizhanyo, A.; Krammer, P.; Summer, S.; Gross, S.; Bragagna, T.; Böhler, C.

2011-03-01

Pantec Biosolutions AG presents a portable fractional ablative laser system based on a miniaturized diode pumped Er:YAG laser. The system can operate at repetition rates up to 500 Hz and has an incorporated beam deflection unit. It is smaller, lighter and cost efficient compared to systems based on lamp pumped Er:YAG lasers and incorporates a skin layer detection to guarantee precise control of the microporation process. The pulse parameters enable a variety of applications in dermatology and in general medicine, as demonstrated by first results on transdermal drug delivery of FSH (follicle stimulating hormone).

An embedded laser marking controller based on ARM and FPGA processors.

PubMed

Dongyun, Wang; Xinpiao, Ye

2014-01-01

Laser marking is an important branch of the laser information processing technology. The existing laser marking machine based on PC and WINDOWS operating system, are large and inconvenient to move. Still, it cannot work outdoors or in other harsh environments. In order to compensate for the above mentioned disadvantages, this paper proposed an embedded laser marking controller based on ARM and FPGA processors. Based on the principle of laser galvanometer scanning marking, the hardware and software were designed for the application. Experiments showed that this new embedded laser marking controller controls the galvanometers synchronously and could achieve precise marking.

Laser technologies in ophthalmic surgery

NASA Astrophysics Data System (ADS)

Atezhev, V. V.; Barchunov, B. V.; Vartapetov, S. K.; Zav'yalov, A. S.; Lapshin, K. E.; Movshev, V. G.; Shcherbakov, I. A.

2016-08-01

Excimer and femtosecond lasers are widely used in ophthalmology to correct refraction. Laser systems for vision correction are based on versatile technical solutions and include multiple hard- and software components. Laser characteristics, properties of laser beam delivery system, algorithms for cornea treatment, and methods of pre-surgical diagnostics determine the surgical outcome. Here we describe the scientific and technological basis for laser systems for refractive surgery developed at the Physics Instrumentation Center (PIC) at the Prokhorov General Physics Institute (GPI), Russian Academy of Sciences.

A simple model for studying rotation errors of gimbal mount axes in laser tracking system based on spherical mirror as a reflection unit

NASA Astrophysics Data System (ADS)

Song, Huixu; Shi, Zhaoyao; Chen, Hongfang; Sun, Yanqiang

2018-01-01

This paper presents a novel experimental approach and a simple model for verifying that spherical mirror of laser tracking system could lessen the effect of rotation errors of gimbal mount axes based on relative motion thinking. Enough material and evidence are provided to support that this simple model could replace complex optical system in laser tracking system. This experimental approach and model interchange the kinematic relationship between spherical mirror and gimbal mount axes in laser tracking system. Being fixed stably, gimbal mount axes' rotation error motions are replaced by spatial micro-displacements of spherical mirror. These motions are simulated by driving spherical mirror along the optical axis and vertical direction with the use of precision positioning platform. The effect on the laser ranging measurement accuracy of displacement caused by the rotation errors of gimbal mount axes could be recorded according to the outcome of laser interferometer. The experimental results show that laser ranging measurement error caused by the rotation errors is less than 0.1 μm if radial error motion and axial error motion are under 10 μm. The method based on relative motion thinking not only simplifies the experimental procedure but also achieves that spherical mirror owns the ability to reduce the effect of rotation errors of gimbal mount axes in laser tracking system.

Method of high precision interval measurement in pulse laser ranging system

NASA Astrophysics Data System (ADS)

Wang, Zhen; Lv, Xin-yuan; Mao, Jin-jin; Liu, Wei; Yang, Dong

2013-09-01

Laser ranging is suitable for laser system, for it has the advantage of high measuring precision, fast measuring speed,no cooperative targets and strong resistance to electromagnetic interference,the measuremen of laser ranging is the key paremeters affecting the performance of the whole system.The precision of the pulsed laser ranging system was decided by the precision of the time interval measurement, the principle structure of laser ranging system was introduced, and a method of high precision time interval measurement in pulse laser ranging system was established in this paper.Based on the analysis of the factors which affected the precision of range measure,the pulse rising edges discriminator was adopted to produce timing mark for the start-stop time discrimination,and the TDC-GP2 high precision interval measurement system based on TMS320F2812 DSP was designed to improve the measurement precision.Experimental results indicate that the time interval measurement method in this paper can obtain higher range accuracy. Compared with the traditional time interval measurement system,the method simplifies the system design and reduce the influence of bad weather conditions,furthermore,it satisfies the requirements of low costs and miniaturization.

Development of a US Gravitational Wave Laser System for LISA

NASA Technical Reports Server (NTRS)

Camp, Jordan B.; Numata, Kenji

2015-01-01

A highly stable and robust laser system is a key component of the space-based LISA mission architecture.In this talk I will describe our plans to demonstrate a TRL 5 LISA laser system at Goddard Space Flight Center by 2016.The laser system includes a low-noise oscillator followed by a power amplifier. The oscillator is a low-mass, compact 10mW External Cavity Laser, consisting of a semiconductor laser coupled to an optical cavity, built by the laser vendorRedfern Integrated Optics. The amplifier is a diode-pumped Yb fiber with 2W output, built at Goddard. I will show noiseand reliability data for the full laser system, and describe our plans to reach TRL 5 by 2016.

CW Laser radar for combustion diagnostics

NASA Astrophysics Data System (ADS)

Malmqvist, Elin; Brydegaard, Mikkel; Aldén, Marcus; Bood, Joakim

2018-04-01

A CW-laser radar system developed for combustion diagnostics is described. The system is based on triangulation to attain range information. A portable system has been constructed and here we show some result from measurements in various flames, for example Rayleigh scattering thermometry and monitoring of particle distributions with high temporal and spatial resolution. The concept can equally well be based on pulsed lasers, allowing suppression of background emission through gated detection.

Method for Ground-to-Satellite Laser Calibration System

NASA Technical Reports Server (NTRS)

Lukashin, Constantine (Inventor); Wielicki, Bruce A. (Inventor)

2015-01-01

The present invention comprises an approach for calibrating the sensitivity to polarization, optics degradation, spectral and stray light response functions of instruments on orbit. The concept is based on using an accurate ground-based laser system, Ground-to-Space Laser Calibration (GSLC), transmitting laser light to instrument on orbit during nighttime substantially clear-sky conditions. To minimize atmospheric contribution to the calibration uncertainty the calibration cycles should be performed in short time intervals, and all required measurements are designed to be relative. The calibration cycles involve ground operations with laser beam polarization and wavelength changes.

Method for Ground-to-Space Laser Calibration System

NASA Technical Reports Server (NTRS)

Lukashin, Constantine (Inventor); Wielicki, Bruce A. (Inventor)

2014-01-01

The present invention comprises an approach for calibrating the sensitivity to polarization, optics degradation, spectral and stray light response functions of instruments on orbit. The concept is based on using an accurate ground-based laser system, Ground-to-Space Laser Calibration (GSLC), transmitting laser light to instrument on orbit during nighttime substantially clear-sky conditions. To minimize atmospheric contribution to the calibration uncertainty the calibration cycles should be performed in short time intervals, and all required measurements are designed to be relative. The calibration cycles involve ground operations with laser beam polarization and wavelength changes.

Propagation and stability characteristics of a 500-m-long laser-based fiducial line for high-precision alignment of long-distance linear accelerators.

PubMed

Suwada, Tsuyoshi; Satoh, Masanori; Telada, Souichi; Minoshima, Kaoru

2013-09-01

A laser-based alignment system with a He-Ne laser has been newly developed in order to precisely align accelerator units at the KEKB injector linac. The laser beam was first implemented as a 500-m-long fiducial straight line for alignment measurements. We experimentally investigated the propagation and stability characteristics of the laser beam passing through laser pipes in vacuum. The pointing stability at the last fiducial point was successfully obtained with the transverse displacements of ±40 μm level in one standard deviation by applying a feedback control. This pointing stability corresponds to an angle of ±0.08 μrad. This report contains a detailed description of the experimental investigation for the propagation and stability characteristics of the laser beam in the laser-based alignment system for long-distance linear accelerators.

Propagation and stability characteristics of a 500-m-long laser-based fiducial line for high-precision alignment of long-distance linear accelerators

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

Suwada, Tsuyoshi; Satoh, Masanori; Telada, Souichi

2013-09-15

A laser-based alignment system with a He-Ne laser has been newly developed in order to precisely align accelerator units at the KEKB injector linac. The laser beam was first implemented as a 500-m-long fiducial straight line for alignment measurements. We experimentally investigated the propagation and stability characteristics of the laser beam passing through laser pipes in vacuum. The pointing stability at the last fiducial point was successfully obtained with the transverse displacements of ±40 μm level in one standard deviation by applying a feedback control. This pointing stability corresponds to an angle of ±0.08 μrad. This report contains a detailedmore » description of the experimental investigation for the propagation and stability characteristics of the laser beam in the laser-based alignment system for long-distance linear accelerators.« less

Research on the laser angle deception jamming technology of laser countermeasure

NASA Astrophysics Data System (ADS)

Ma, Shi-wei; Chen, Wen-jian; Gao, Wei; Duan, Yuan-yuan

2015-10-01

In recent years , laser guided weapons behave very well at destroying the military goals in the local wars, the single-shot probability, effective range and hitting precision getting better. And the semi-active laser guided weapons are the most widely used laser guided weapons. In order to improve the viability and protect important military goals, it's necessary to study the technology to against the semi-active guided weapons. This paper studies the working principle, the advantages and disadvantages of the semi-active guided weapons at first, and analyze the possibility of laser angle deception jamming system working. Then it analyzes the working principle and process of laser angle deception jamming technology. Finally it designs a half-real simulation system of laser angle deception jamming, which consists of semi-active laser guided weapons simulation system and laser angle deception jamming system. The simulation system demonstrates the working process of the laser angle deception jamming system. This paper provides fundamental base for the research on the countermeasure technology of semi-active laser guided weapons.

Spatio-temporal characterisation of a 100 kHz 24 W sub-3-cycle NOPCPA laser system

NASA Astrophysics Data System (ADS)

Witting, Tobias; Furch, Federico J.; Vrakking, Marc J. J.

2018-04-01

In recent years, OPCPA and NOPCPA laser systems have shown the potential to supersede Ti:sapphire plus post-compression based laser systems to drive next generation attosecond light sources via direct amplification of few-cycle pulses to high pulse energies at high repetition rates. In this paper, we present a sub 3-cycle, 100 kHz, 24 W NOPA laser system and characterise its spatio-temporal properties using the SEA-F-SPIDER technique. Our results underline the importance of spatio-temporal diagnostics for these emerging laser systems.

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.

Green high-power tunable external-cavity GaN diode laser at 515  nm.

PubMed

Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

2016-09-15

A 480 mW green tunable diode laser system is demonstrated for the first time to our knowledge. The laser system is based on a GaN broad-area diode laser and Littrow external-cavity feedback. The green laser system is operated in two modes by switching the polarization direction of the laser beam incident on the grating. When the laser beam is p-polarized, an output power of 50 mW with a tunable range of 9.2 nm is achieved. When the laser beam is s-polarized, an output power of 480 mW with a tunable range of 2.1 nm is obtained. This constitutes the highest output power from a tunable green diode laser system.

Laser system development for gravitational-wave interferometry in space

NASA Astrophysics Data System (ADS)

Numata, Kenji; Yu, Anthony W.; Camp, Jordan B.; Krainak, Michael A.

2018-02-01

A highly stable and robust laser system is a key component of the space-based Laser Interferometer Space Antenna (LISA) mission, which is designed to detect gravitational waves from various astronomical sources. The baseline architecture for the LISA laser consists of a low-power, low-noise Nd:YAG non-planar ring oscillator (NPRO) followed by a diode-pumped Yb-fiber amplifier with 2 W output. We are developing such laser system at the NASA Goddard Space Flight Center (GSFC), as well as investigating other laser options. In this paper, we will describe our progress to date and plans to demonstrate a technology readiness level (TRL) 6 LISA laser system.

A new three-dimensional nonscanning laser imaging system based on the illumination pattern of a point-light-source array

NASA Astrophysics Data System (ADS)

Xia, Wenze; Ma, Yayun; Han, Shaokun; Wang, Yulin; Liu, Fei; Zhai, Yu

2018-06-01

One of the most important goals of research on three-dimensional nonscanning laser imaging systems is the improvement of the illumination system. In this paper, a new three-dimensional nonscanning laser imaging system based on the illumination pattern of a point-light-source array is proposed. This array is obtained using a fiber array connected to a laser array with each unit laser having independent control circuits. This system uses a point-to-point imaging process, which is realized using the exact corresponding optical relationship between the point-light-source array and a linear-mode avalanche photodiode array detector. The complete working process of this system is explained in detail, and the mathematical model of this system containing four equations is established. A simulated contrast experiment and two real contrast experiments which use the simplified setup without a laser array are performed. The final results demonstrate that unlike a conventional three-dimensional nonscanning laser imaging system, the proposed system meets all the requirements of an eligible illumination system. Finally, the imaging performance of this system is analyzed under defocusing situations, and analytical results show that the system has good defocusing robustness and can be easily adjusted in real applications.

Applications of FM-CW laser radar to antenna contour mapping

NASA Technical Reports Server (NTRS)

Slotwinski, A. R.

1989-01-01

The FM-CW coherent laser radar concept, based on the FM radar principle which makes use of the coherence and lunability of injection laser diodes, is discussed. Laser radar precision/time tradeoffs, block diagrams, system performance, fiber optic system implantation, and receiver improvements are briefly described.

Performance of the GLAS Laser Transmitter in Space

NASA Technical Reports Server (NTRS)

Yu, Anthony W.; Afzal, Robert S.; Dallas, Joseph L.; Melak, Anthony; Mamakos, William

2006-01-01

The Geoscience Laser Altimeter System (GLAS), launched in January 2003, is a laser altimeter and lidar for the Earth Observing System's (EOS) ICESat mission. The laser transmitter requirements, design and qualification test results and in-flight performance for this space-based remote sensing instrument is summarized and presented.

SPECIAL ISSUE ON OPTICAL PROCESSING OF INFORMATION: Information transmission systems based on two-mode lasers with controlled emission frequencies

NASA Astrophysics Data System (ADS)

Naumov, N. V.; Petrovskii, V. N.; Protsenko, E. D.; Shananin, R. A.

1995-10-01

Various information transmission systems, based on two-mode lasers with controlled emission frequencies, are proposed. It is suggested that these systems can be implemented by modulation of the intermode spacing of a two-mode laser. An experimental investigation is reported of frequency control methods. It is shown that these methods should make it possible to construct information transmission systems with high transmission rates subject to weak nonlinear distortions of the information-carrying signal.

Fiber Based Seed Laser for CO 2 Ultrafast Laser Systems

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

Chen, Yuchuan

A compact and effective 10-micron femtosecond laser with pulse duration <500fs and repetition rate of >100Hz or smaller is desirable by DOE for seeding CO 2 ultrafast laser systems to improve the stability, reliability and efficiency in generating 10-micron laser from GW up to 100TW peak power, which is irreplaceable in driving an accelerator for particle beam generation due to the efficiency proportional to the square of the laser wavelength. Agiltron proposes a fiber based ultrafast 10-micron seed laser that can provide the required specifications and high performance. Its success will directly benefit DOE’s compact proton and ion sources. Themore » innovative technology can be used for ultrafast laser generation over the whole mid-IR range, and speed up the development of mid-IR laser applications. Agiltron, Inc. has successfully completed all tasks and demonstrated the feasibility of a fiber based 10-micron ultrafast laser in Phase I of the Program. We built a mode-locked fiber laser that generated < 400fs ultrafast laser pulses and successfully controlled the repetition rate to be the required 100Hz. Using this mode-locked laser, we demonstrated the feasibility of parametric femtosecond laser generation based on frequency down conversion. The experimental results agree with our simulation results. The investigation results of Phase I will be used to optimize the design of the laser system and build a fully functional prototype for delivery to the DOE in the Phase II program. The prototype development in Phase II program will be in the collaboration with Professor Chandrashekhar Joshi, the leader of UCLA Laser-Plasma group. Prof. Joshi discovered a new mechanism for generation of monoenergetic proton/ion beams: Shock Wave Acceleration in a near critical density plasma and demonstrated that high-energy proton beams using CO 2 laser driven collisionless shocks in a gas jet plasma, which opened an opportunity to develop a rather compact high-repetition rate ion source for medical and other applications which could be significantly cheaper than that based on RF acceleration. We propose an output energy >1 μJ, one order of magnitude higher than the DOE original requirement. The performance of the prototype will be tested at UCLA by directly seeding the CO 2 laser system driving an accelerator.« less

A simple laser locking system based on a field-programmable gate array.

PubMed

Jørgensen, N B; Birkmose, D; Trelborg, K; Wacker, L; Winter, N; Hilliard, A J; Bason, M G; Arlt, J J

2016-07-01

Frequency stabilization of laser light is crucial in both scientific and industrial applications. Technological developments now allow analog laser stabilization systems to be replaced with digital electronics such as field-programmable gate arrays, which have recently been utilized to develop such locking systems. We have developed a frequency stabilization system based on a field-programmable gate array, with emphasis on hardware simplicity, which offers a user-friendly alternative to commercial and previous home-built solutions. Frequency modulation, lock-in detection, and a proportional-integral-derivative controller are programmed on the field-programmable gate array and only minimal additional components are required to frequency stabilize a laser. The locking system is administered from a host-computer which provides comprehensive, long-distance control through a versatile interface. Various measurements were performed to characterize the system. The linewidth of the locked laser was measured to be 0.7 ± 0.1 MHz with a settling time of 10 ms. The system can thus fully match laser systems currently in use for atom trapping and cooling applications.

A simple laser locking system based on a field-programmable gate array

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

Jørgensen, N. B.; Birkmose, D.; Trelborg, K.

Frequency stabilization of laser light is crucial in both scientific and industrial applications. Technological developments now allow analog laser stabilization systems to be replaced with digital electronics such as field-programmable gate arrays, which have recently been utilized to develop such locking systems. We have developed a frequency stabilization system based on a field-programmable gate array, with emphasis on hardware simplicity, which offers a user-friendly alternative to commercial and previous home-built solutions. Frequency modulation, lock-in detection, and a proportional-integral-derivative controller are programmed on the field-programmable gate array and only minimal additional components are required to frequency stabilize a laser. The lockingmore » system is administered from a host-computer which provides comprehensive, long-distance control through a versatile interface. Various measurements were performed to characterize the system. The linewidth of the locked laser was measured to be 0.7 ± 0.1 MHz with a settling time of 10 ms. The system can thus fully match laser systems currently in use for atom trapping and cooling applications.« less

Semiconductor-based narrow-line and high-brilliance 193-nm laser system for industrial applications

NASA Astrophysics Data System (ADS)

Opalevs, D.; Scholz, M.; Stuhler, J.; Gilfert, C.; Liu, L. J.; Wang, X. Y.; Vetter, A.; Kirner, R.; Scharf, T.; Noell, W.; Rockstuhl, C.; Li, R. K.; Chen, C. T.; Voelkel, R.; Leisching, P.

2018-02-01

We present a novel industrial-grade prototype version of a continuous-wave 193 nm laser system entirely based on solid state pump laser technology. Deep-ultraviolet emission is realized by frequency-quadrupling an amplified diode laser and up to 20 mW of optical power were generated using the nonlinear crystal KBBF. We demonstrate the lifetime of the laser system for different output power levels and environmental conditions. The high stability of our setup was proven in > 500 h measurements on a single spot, a crystal shifter multiplies the lifetime to match industrial requirements. This laser improves the relative intensity noise, brilliance, wall-plug efficiency and maintenance cost significantly. We discuss first lithographic experiments making use of this improvement in photon efficiency.

From Dye Laser Factory to Portable Semiconductor Laser: Four Generations of Sodium Guide Star Lasers for Adaptive Optics in Astronomy and Space Situational Awareness

NASA Astrophysics Data System (ADS)

d'Orgeville, C.; Fetzer, G.

This presentation recalls the history of sodium guide star laser systems used in astronomy and space situational awareness adaptive optics, analysing the impact that sodium laser technology evolution has had on routine telescope operations. While it would not be practical to describe every single sodium guide star laser system developed to date, it is possible to characterize their evolution in broad technology terms. The first generation of sodium lasers used dye laser technology to create the first sodium laser guide stars in Hawaii, California, and Spain in the late 1980's and 1990's. These experimental systems were turned into the first laser guide star facilities to equip medium-to-large diameter adaptive optics telescopes, opening a new era of LGS AO-enabled diffraction-limited imaging from the ground. Although they produced exciting scientific results, these laser guide star facilities were large, power-hungry and messy. In the USA, a second-generation of sodium lasers was developed in the 2000's that used cleaner, yet still large and complex, solid-state laser technology. These are the systems in routine operation at the 8-10m class astronomical telescopes and 4m-class satellite imaging facilities today. Meanwhile in Europe, a third generation of sodium lasers was being developed using inherently compact and efficient fiber laser technology, and resulting in the only commercially available sodium guide star laser system to date. Fiber-based sodium lasers will be deployed at two astronomical telescopes and at least one space debris tracking station this year. Although highly promising, these systems remain significantly expensive and they have yet to demonstrate high performance in the field. We are proposing to develop a fourth generation of sodium lasers: based on semiconductor technology, these lasers could provide the final solution to the problem of sodium laser guide star adaptive optics for all astronomy and space situational awareness applications.

Design of optical axis jitter control system for multi beam lasers based on FPGA

NASA Astrophysics Data System (ADS)

Ou, Long; Li, Guohui; Xie, Chuanlin; Zhou, Zhiqiang

2018-02-01

A design of optical axis closed-loop control system for multi beam lasers coherent combining based on FPGA was introduced. The system uses piezoelectric ceramics Fast Steering Mirrors (FSM) as actuator, the Fairfield spot detection of multi beam lasers by the high speed CMOS camera for optical detecting, a control system based on FPGA for real-time optical axis jitter suppression. The algorithm for optical axis centroid detecting and PID of anti-Integral saturation were realized by FPGA. Optimize the structure of logic circuit by reuse resource and pipeline, as a result of reducing logic resource but reduced the delay time, and the closed-loop bandwidth increases to 100Hz. The jitter of laser less than 40Hz was reduced 40dB. The cost of the system is low but it works stably.

An Embedded Laser Marking Controller Based on ARM and FPGA Processors

PubMed Central

Dongyun, Wang; Xinpiao, Ye

2014-01-01

Laser marking is an important branch of the laser information processing technology. The existing laser marking machine based on PC and WINDOWS operating system, are large and inconvenient to move. Still, it cannot work outdoors or in other harsh environments. In order to compensate for the above mentioned disadvantages, this paper proposed an embedded laser marking controller based on ARM and FPGA processors. Based on the principle of laser galvanometer scanning marking, the hardware and software were designed for the application. Experiments showed that this new embedded laser marking controller controls the galvanometers synchronously and could achieve precise marking. PMID:24772028

Influence of spatial beam inhomogeneities on the parameters of a petawatt laser system based on multi-stage parametric amplification

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

Frolov, S A; Trunov, V I; Pestryakov, Efim V

2013-05-31

We have developed a technique for investigating the evolution of spatial inhomogeneities in high-power laser systems based on multi-stage parametric amplification. A linearised model of the inhomogeneity development is first devised for parametric amplification with the small-scale self-focusing taken into account. It is shown that the application of this model gives the results consistent (with high accuracy and in a wide range of inhomogeneity parameters) with the calculation without approximations. Using the linearised model, we have analysed the development of spatial inhomogeneities in a petawatt laser system based on multi-stage parametric amplification, developed at the Institute of Laser Physics, Siberianmore » Branch of the Russian Academy of Sciences (ILP SB RAS). (control of laser radiation parameters)« less

Laser capture microdissection: should an ultraviolet or infrared laser be used?

PubMed

Vandewoestyne, Mado; Goossens, Karen; Burvenich, Christian; Van Soom, Ann; Peelman, Luc; Deforce, Dieter

2013-08-15

Laser capture microdissection (LCM) is a well-established cell separation technique. It combines microscopy with laser beam technology and allows targeting of specific cells or tissue regions that need to be separated from others. Consequently, this biological material can be used for genome or transcriptome analyses. Appropriate methods of sample preparation, however, are crucial for the success of downstream molecular analysis. The aim of this study was to objectively compare the two main LCM systems, one based on an ultraviolet (UV) laser and the other based on an infrared (IR) laser, on different criteria ranging from user-friendliness to sample quality. The comparison was performed on two types of samples: peripheral blood mononuclear cells and blastocysts. The UV laser LCM system had several advantages over the IR laser LCM system. Not only does the UV system allow faster and more precise sample collection, but also the obtained samples-even single cell samples-can be used for DNA extraction and downstream polymerase chain reaction (PCR) applications. RNA-based applications are more challenging for both LCM systems. Although sufficient RNA can be extracted from as few as 10 cells for reverse transcription quantitative PCR (RT-qPCR) analysis, the low RNA quality should be taken into account when designing the RT-qPCR assays. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Advancement of High Power Quasi-CW Laser Diode Arrays For Space-based Laser Instruments

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin; Meadows, Byron L.; Baker, nathaniel R.; Baggott, Renee S.; Singh, Upendra N.; Kavaya, Michael J.

2004-01-01

Space-based laser and lidar instruments play an important role in NASA s plans for meeting its objectives in both Earth Science and Space Exploration areas. Almost all the lidar instrument concepts being considered by NASA scientist utilize moderate to high power diode-pumped solid state lasers as their transmitter source. Perhaps the most critical component of any solid state laser system is its pump laser diode array which essentially dictates instrument efficiency, reliability and lifetime. For this reason, premature failures and rapid degradation of high power laser diode arrays that have been experienced by laser system designers are of major concern to NASA. This work addresses these reliability and lifetime issues by attempting to eliminate the causes of failures and developing methods for screening laser diode arrays and qualifying them for operation in space.

Investigation of laser polarized xenon magnetic resonance

NASA Technical Reports Server (NTRS)

Walsworth, Ronald L.

1998-01-01

Ground-based investigations of a new biomedical diagnostic technology: nuclear magnetic resonance of laser polarized noble gas are addressed. The specific research tasks discussed are: (1) Development of a large-scale noble gas polarization system; (2) biomedical investigations using laser polarized noble gas in conventional (high magnetic field) NMR systems; and (3) the development and application of a low magnetic field system for laser polarized noble gas NMR.

Four generations of sodium guide star lasers for adaptive optics in astronomy and space situational awareness

NASA Astrophysics Data System (ADS)

d'Orgeville, Céline; Fetzer, Gregory J.

2016-07-01

This paper recalls the history of sodium guide star laser systems used in astronomy and space situational awareness adaptive optics, analyzing the impact that sodium laser technology evolution has had on routine telescope operations. While it would not be practical to describe every single sodium guide star laser system developed to date, it is possible to characterize their evolution in broad technology terms. The first generation of sodium lasers used dye laser technology to create the first sodium laser guide stars in Hawaii, California, and Spain in the late 1980s and 1990s. These experimental systems were turned into the first laser guide star facilities to equip mediumto- large diameter adaptive optics telescopes, opening a new era of Laser Guide Star Adaptive Optics (LGS AO)-enabled diffraction-limited imaging from the ground. Although they produced exciting scientific results, these laser guide star facilities were large, power-hungry and messy. In the USA, a second-generation of sodium lasers was developed in the 2000s that used cleaner, yet still large and complex, solid-state laser technology. These are the systems in routine operation at the 8 to 10m-class astronomical telescopes and 4m-class satellite imaging facilities today. Meanwhile in Europe, a third generation of sodium lasers was being developed using inherently compact and efficient fiber laser technology, and resulting in the only commercially available sodium guide star laser system to date. Fiber-based sodium lasers are being or will soon be deployed at three astronomical telescopes and two space surveillance stations. These highly promising systems are still relatively large to install on telescopes and they remain significantly expensive to procure and maintain. We are thus proposing to develop a fourth generation of sodium lasers: based on semiconductor technology, these lasers could provide a definitive solution to the problem of sodium LGS AO laser sources for all astronomy and space situational awareness applications.

Performance calculation and simulation system of high energy laser weapon

NASA Astrophysics Data System (ADS)

Wang, Pei; Liu, Min; Su, Yu; Zhang, Ke

2014-12-01

High energy laser weapons are ready for some of today's most challenging military applications. Based on the analysis of the main tactical/technical index and combating process of high energy laser weapon, a performance calculation and simulation system of high energy laser weapon was established. Firstly, the index decomposition and workflow of high energy laser weapon was proposed. The entire system was composed of six parts, including classical target, platform of laser weapon, detect sensor, tracking and pointing control, laser atmosphere propagation and damage assessment module. Then, the index calculation modules were designed. Finally, anti-missile interception simulation was performed. The system can provide reference and basis for the analysis and evaluation of high energy laser weapon efficiency.

Parametric study of laser photovoltaic energy converters

NASA Technical Reports Server (NTRS)

Walker, G. H.; Heinbockel, J. H.

1987-01-01

Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.

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.

Visual servoing of a laser ablation based cochleostomy

NASA Astrophysics Data System (ADS)

Kahrs, Lüder A.; Raczkowsky, Jörg; Werner, Martin; Knapp, Felix B.; Mehrwald, Markus; Hering, Peter; Schipper, Jörg; Klenzner, Thomas; Wörn, Heinz

2008-03-01

The aim of this study is a defined, visually based and camera controlled bone removal by a navigated CO II laser on the promontory of the inner ear. A precise and minimally traumatic opening procedure of the cochlea for the implantation of a cochlear implant electrode (so-called cochleostomy) is intended. Harming the membrane linings of the inner ear can result in damage of remaining organ functions (e.g. complete deafness or vertigo). A precise tissue removal by a laser-based bone ablation system is investigated. Inside the borehole the pulsed laser beam is guided automatically over the bone by using a two mirror galvanometric scanner. The ablation process is controlled by visual servoing. For the detection of the boundary layers of the inner ear the ablation area is monitored by a color camera. The acquired pictures are analyzed by image processing. The results of this analysis are used to control the process of laser ablation. This publication describes the complete system including image processing algorithms and the concept for the resulting distribution of single laser pulses. The system has been tested on human cochleae in ex-vivo studies. Further developments could lead to safe intraoperative openings of the cochlea by a robot based surgical laser instrument.

Tunable Laser Development for In-Flight Fiber Optic Based Structural Health Monitoring Systems

NASA Technical Reports Server (NTRS)

Richards, Lance; Parker, Allen; Chan, Patrick

2013-01-01

Briefing based on tunable laser development for in flight fiber optic based structural health monitoring systems. The objective of this task is to investigate, develop, and demonstrate a low-cost swept lasing light source for NASA DFRC's fiber optics sensing system (FOSS) to perform structural health monitoring on current and future aerospace vehicles.

Real-time laser cladding control with variable spot size

NASA Astrophysics Data System (ADS)

Arias, J. L.; Montealegre, M. A.; Vidal, F.; Rodríguez, J.; Mann, S.; Abels, P.; Motmans, F.

2014-03-01

Laser cladding processing has been used in different industries to improve the surface properties or to reconstruct damaged pieces. In order to cover areas considerably larger than the diameter of the laser beam, successive partially overlapping tracks are deposited. With no control over the process variables this conduces to an increase of the temperature, which could decrease mechanical properties of the laser cladded material. Commonly, the process is monitored and controlled by a PC using cameras, but this control suffers from a lack of speed caused by the image processing step. The aim of this work is to design and develop a FPGA-based laser cladding control system. This system is intended to modify the laser beam power according to the melt pool width, which is measured using a CMOS camera. All the control and monitoring tasks are carried out by a FPGA, taking advantage of its abundance of resources and speed of operation. The robustness of the image processing algorithm is assessed, as well as the control system performance. Laser power is decreased as substrate temperature increases, thus maintaining a constant clad width. This FPGA-based control system is integrated in an adaptive laser cladding system, which also includes an adaptive optical system that will control the laser focus distance on the fly. The whole system will constitute an efficient instrument for part repair with complex geometries and coating selective surfaces. This will be a significant step forward into the total industrial implementation of an automated industrial laser cladding process.

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.

Forming a single layer of a composite powder based on the Ti-Nb system via selective laser melting (SLM)

NASA Astrophysics Data System (ADS)

Saprykin, A. A.; Sharkeev, Yu P.; Ibragimov, E. A.; Babakova, E. V.; Dudikhin, D. V.

2016-07-01

Alloys based on the titanium-niobium system are widely used in implant production. It is conditional, first of all, on the low modulus of elasticity and bio-inert properties of an alloy. These alloys are especially important for tooth replacement and orthopedic surgery. At present alloys based on the titanium-niobium system are produced mainly using conventional metallurgical methods. The further subtractive manufacturing an end product results in a lot of wastes, increasing, therefore, its cost. The alternative of these processes is additive manufacturing. Selective laser melting is a technology, which makes it possible to synthesize products of metal powders and their blends. The point of this technology is laser melting a layer of a powdered material; then a sintered layer is coated with the next layer of powder etc. Complex products and working prototypes are made on the base of this technology. The authors of this paper address to the issue of applying selective laser melting in order to synthesize a binary alloy of a composite powder based on the titanium-niobium system. A set of 10x10 mm samples is made in various process conditions. The samples are made by an experimental selective laser synthesis machine «VARISKAF-100MB». The machine provides adjustment of the following process variables: laser emission power, scanning rate and pitch, temperature of powder pre-heating, thickness of the layer to be sprinkled, and diameter of laser spot focusing. All samples are made in the preliminary vacuumized shielding atmosphere of argon. The porosity and thickness of the sintered layer related to the laser emission power are shown at various scanning rates. It is revealed that scanning rate and laser emission power are adjustable process variables, having the greatest effect on forming the sintered layer.

Current Status of Study on Hydrogen Production with Space Solar Power Systems (SSPS)

NASA Astrophysics Data System (ADS)

Mori, M.; Kagawa, H.; Nagayama, H.; Saito, Y.

2004-12-01

Japan Aerospace Exploration Agency (JAXA) has been conducting studies on Space Solar Power Systems (SSPS) using microwave and laser beams for years since FY1998 organizing a special committee and working groups. The microwave based SSPS are huge solar power systems that generate GW power by solar cells. The electric power is transmitted via microwave from the SSPS to the ground. In the laser based SSPS, a solar condenser equipped with lenses or mirrors and laser-generator would be put into orbit. A laser beam would be sent to Earth-based hydrogen generating device. We are proposing a roadmap that consists of a stepwise approach to achieve commercial SSPS in 20-30 years. The first step is 50kW class Technology Demonstration Satellite to demonstrate microwave power transmission. The second step is to demonstrate robotic assembly of 10MW class large scale flexible structure in space on ISS co-orbit. The third step is to build a prototype SSPS in GEO. The final step is to build commercial SSPS in GEO. We continue the study of SSPS concepts and architectures, technology flight demonstration and major technology development. System design of tens of kW class Technology Demonstration Satellite and conceptual study of 10MW class demonstration system on ISS co-orbit are also conducted. Several key technologies which are needed to be developed in appropriate R&D roadmap, such as high-voltage solar cell array, fiber type of direct solar pumping solid-state laser, high efficiency magnetron, thermal control technology and control technology of large scale flexible structure etc. are also investigated. In the study of concept design of commercial SSPS mentioned above, we have studied some configurations of both microwave based SSPS and laser based SSPS. In case of microwave based SSPS, the solar energy must be converted to electricity and then converted to a microwave beam. The on-ground rectifying antenna will collect the microwave beam and convert it to electricity to connect to commercial power grids. From the past experiences of the conceptual design of the1GW class SSPS, it is clear that system with the mirrors and modularized unit which integrated solar cells and microwave power transmitters is promising. In this type of SSPS, the solar lights are directed to the energy conversion unit integrated solar cells and microwave power transmitters using mirrors. The key factor in designing systems is feasibility of thermal system. Considering above these factors, some reference models are being considered now. FY2003 reference model is the model for formation flight without the center truss which connect to primary mirrors to energy conversion unit. Using this model as basis, we are carrying out examination from various viewpoints aiming at the cost minimum to build and maintain the systems. In case of laser based SSPS, the laser beam would be directly produced from the solar light using the direct solar pumping solid-state laser device. This laser beams would be collected on ground and used to produce hydrogen from seawater. The receiving / energy conversion station is settled on an ocean, and producing hydrogen can be stored and transported by ships to consumers. In designing laser based SSPS, conversion efficiency of the direct solar pumping solid-state laser and feasibility of thermal system are critical factors. Since magnification of solar concentrator is very high, improvement of thermal control system is important. Feasibility of its ground facilities and production technology of hydrogen using laser beams has been also studied. Both hydrogen generating systems with photo-catalyst device and electrolytic ones have been examined. From the past experiences of this study, high efficient electric power generating technology using the solar cell which suited the wavelength of laser is promising. The life cycle cost model of laser based SSPS was created and evaluated its validity. Sensitivity analysis of laser based SSPS are also continued aiming at hydrogen generating cost of around 20 cent per Nm3 . This paper presents a summary of studies on SSPS that JAXA has examined.

The choice: Welding with CO2 or Nd:YAG lasers

NASA Astrophysics Data System (ADS)

Leong, Keng H.

The recent commercial availability of multi-kilowatt Nd:YAG lasers has opened new avenues for rapid laser processing as well as intensified the competition (cost effectiveness) between CO2 and Nd:YAG laser systems. Vendors offering Nd:YAG laser systems may claim lower operating costs (than CO2) and fiberoptic beam delivery flexibility while CO2 systems vendors may emphasize lower capital cost and well established processing requirements and experience. The capital and operating costs of a laser system are impacted by demand and supply economics and technological advances. Frequently the total cost of a workcell using a laser for processing has to be considered rather than the laser system alone. Consequently it is not very practical to approach the selection of a laser system based on its capital cost and estimated operating cost only. This presentation describes a more pragmatic approach to aid the user in the selection of the optimal multi-kilowatt laser system for a particular processing requirement with emphasis on welding. CO2 laser systems are well established on the factory floor. Consequently, emphasis is given to the comparative application of Nd:YAG lasers, process requirements and performance. Requirements for the laser welding of different metals are examined in the context of hardware (laser system and beam delivery) selection and examples of welding speeds that can be achieved using CO2 and Nd:YAG lasers are examined.

Characterization of FBG sensor interrogation based on a FDML wavelength swept laser

PubMed Central

Jung, Eun Joo; Kim, Chang-Seok; Jeong, Myung Yung; Kim, Moon Ki; Jeon, Min Yong; Jung, Woonggyu; Chen, Zhongping

2012-01-01

In this study, we develop an ultra-fast fiber Bragg grating sensor system that is based on the Fourier domain mode-locked (FDML) swept laser. A FDML wavelength swept laser has many advantages compared to the conventional wavelength swept laser source, such as high-speed interrogation, narrow spectral sensitivity, and high phase stability. The newly developed FDML wavelength swept laser shows a superior performance of a high scan rate of 31.3 kHz and a broad scan range of over 70 nm simultaneously. The performance of the grating sensor interrogating system using a FDML wavelength swept laser is characterized in both static and dynamic strain responses. PMID:18852764

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.

Laser-phased-array beam steering based on crystal fiber

NASA Astrophysics Data System (ADS)

Yang, Deng-cai; Zhao, Si-si; Wang, Da-yong; Wang, Zhi-yong; Zhang, Xiao-fei

2011-06-01

Laser-phased-array system provides an elegant means for achieving the inertial-free, high-resolution, rapid and random beam steering. In laser-phased-array system, phase controlling is the most important factor that impacts the system performance. A novel scheme is provided in this paper, the beam steering is accomplished by using crystal fiber array, the difference length between adjacent fiber is fixed. The phase difference between adjacent fiber decides the direction of the output beam. When the wavelength of the input fiber laser is tuned, the phase difference between the adjacent elements has changed. Therefore, the laser beam direction has changed and the beam steering has been accomplished. In this article, based on the proposed scheme, the steering angle of the laser beam is calculated and analyzed theoretically. Moreover, the far-field steering beam quality is discussed.

Note: Reliable and non-contact 6D motion tracking system based on 2D laser scanners for cargo transportation

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

Kim, Young-Keun, E-mail: ykkim@handong.edu; Kim, Kyung-Soo

Maritime transportation demands an accurate measurement system to track the motion of oscillating container boxes in real time. However, it is a challenge to design a sensor system that can provide both reliable and non-contact methods of 6-DOF motion measurements of a remote object for outdoor applications. In the paper, a sensor system based on two 2D laser scanners is proposed for detecting the relative 6-DOF motion of a crane load in real time. Even without implementing a camera, the proposed system can detect the motion of a remote object using four laser beam points. Because it is a laser-basedmore » sensor, the system is expected to be highly robust to sea weather conditions.« less

Laser based analysis using a passively Q-switched laser employing analysis electronics and a means for detecting atomic optical emission of the laser media

DOEpatents

Woodruff, Steven D.; Mcintyre, Dustin L.

2016-03-29

A device for Laser based Analysis using a Passively Q-Switched Laser comprising an optical pumping source optically connected to a laser media. The laser media and a Q-switch are positioned between and optically connected to a high reflectivity mirror (HR) and an output coupler (OC) along an optical axis. The output coupler (OC) is optically connected to the output lens along the optical axis. A means for detecting atomic optical emission comprises a filter and a light detector. The optical filter is optically connected to the laser media and the optical detector. A control system is connected to the optical detector and the analysis electronics. The analysis electronics are optically connected to the output lens. The detection of the large scale laser output production triggers the control system to initiate the precise timing and data collection from the detector and analysis.

Laser-based optoelectronic system for therapy by medical treatment of cardiovascular diseases

NASA Astrophysics Data System (ADS)

Chtchoupak, Oleg S.; Spilevoi, Boris N.; Zapaeva, Natlia L.

1996-04-01

The method and system's design for the laser treatment of the heart ischemia is presented. Our conceptual approach to the development of the system is based on the theoretical and experimental works about positive influence of low intensity near infrared laser irradiation by treatment of cardiovascular diseases. The method and system allow it to influence the subepicardial collateral blood circulation with near infrared (NIR) laser irradiation in wavelength ranges of 0.86 - 1.06 mkm. The presented techniques make it possible to achieve a higher effectiveness of treatment. First, due to individual choice of radiation parameters on the basis of analysis of the patient's conditions before and after laser therapy. Second, due to simultaneous influence at several points of the human body. Finally, results of the clinical tests are presented, which confirm the discussed methods.

Geometric calibration of a coordinate measuring machine using a laser tracking system

NASA Astrophysics Data System (ADS)

Umetsu, Kenta; Furutnani, Ryosyu; Osawa, Sonko; Takatsuji, Toshiyuki; Kurosawa, Tomizo

2005-12-01

This paper proposes a calibration method for a coordinate measuring machine (CMM) using a laser tracking system. The laser tracking system can measure three-dimensional coordinates based on the principle of trilateration with high accuracy and is easy to set up. The accuracy of length measurement of a single laser tracking interferometer (laser tracker) is about 0.3 µm over a length of 600 mm. In this study, we first measured 3D coordinates using the laser tracking system. Secondly, 21 geometric errors, namely, parametric errors of the CMM, were estimated by the comparison of the coordinates obtained by the laser tracking system and those obtained by the CMM. As a result, the estimated parametric errors agreed with those estimated by a ball plate measurement, which demonstrates the validity of the proposed calibration system.

Rapid Prototyping: State of the Art

DTIC Science & Technology

2003-10-23

Rapid Prototyping SCS Solid Creation System SLM Selective Laser Melting SLP Solid Laser diode Plotter SLS Selective Laser Sintering SOAR State of the...121,000, respectively. SLP stands for Sold Laser Diode Plotter. The machines are relatively slow and parts are small, so, to date, the products have been...Gigerenzer, H., “Directed Laser Welding of Metal Matrix Composite Structures for Space Based Applications,“ Triton Systems Inc., Chelmsford, MA., 1

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.

Optical air data systems and methods

NASA Technical Reports Server (NTRS)

Spaeth, Lisa G. (Inventor); O'Brien, Martin (Inventor); Tang, Shoou-yu (Inventor); Acott, Phillip E. (Inventor); Caldwell, Loren M. (Inventor)

2011-01-01

Systems and methods for sensing air includes at least one, and in some embodiments three, transceivers for projecting the laser energy as laser radiation to the air. The transceivers are scanned or aligned along several different axes. Each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines air temperatures, wind speeds, and wind directions based on the scattered laser radiation. Applications of the system to wind power site evaluation, wind turbine control, traffic safety, general meteorological monitoring and airport safety are presented.

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.

Gold nanoparticle-based plasmonic random fiber laser

NASA Astrophysics Data System (ADS)

Hu, Zhijia; Liang, Yunyun; Xie, Kang; Gao, Pengfei; Zhang, Douguo; Jiang, Haiming; Shi, Fan; Yin, Leicheng; Gao, Jiangang; Ming, Hai; Zhang, Qijin

2015-03-01

We have reported the realization of a plasmonic random fiber laser based on the localized surface plasmonic resonance of gold nanoparticles (NPs) in the liquid core optical fiber. The liquid core material contains a dispersive solution of gold NPs and laser dye pyrromethene 597 in toluene. It was experimentally proved that the fluorescence quenching of the dye is restrained in the optical fiber, which is considered one of the main sources of loss in the traditional laser system. Meanwhile, the random lasing can be more easily obtained in the random laser system with more overlap between the plasmonic resonance of the gold NPs and the photoluminescence spectrum of the dye molecules.

Laser energy conversion

NASA Technical Reports Server (NTRS)

Jalufka, N. W.

1989-01-01

The conversion of laser energy to other, more useful, forms is an important element of any space power transmission system employing lasers. In general the user, at the receiving sight, will require the energy in a form other than laser radiation. In particular, conversion to rocket power and electricity are considered to be two major areas where one must consider various conversion techniques. Three systems (photovoltaic cells, MHD generators, and gas turbines) have been identified as the laser-to-electricity conversion systems that appear to meet most of the criteria for a space-based system. The laser thruster also shows considerable promise as a space propulsion system. At this time one cannot predict which of the three laser-to-electric converters will be best suited to particular mission needs. All three systems have some particular advantages, as well as disadvantages. It would be prudent to continue research on all three systems, as well as the laser rocket thruster. Research on novel energy conversion systems, such as the optical rectenna and the reverse free-electron laser, should continue due to their potential for high payoff.

Bulk-wave ultrasonic propagation imagers

NASA Astrophysics Data System (ADS)

Abbas, Syed Haider; Lee, Jung-Ryul

2018-03-01

Laser-based ultrasound systems are described that utilize the ultrasonic bulk-wave sensing to detect the damages and flaws in the aerospace structures. These systems apply pulse-echo or through transmission methods to detect longitudinal through-the-thickness bulk-waves. These thermoelastic waves are generated using Q-switched laser and non-contact sensing is performed using a laser Doppler vibrometer (LDV). Laser-based raster scanning is performed by either twoaxis translation stage for linear-scanning or galvanometer-based laser mirror scanner for angular-scanning. In all ultrasonic propagation imagers, the ultrasonic data is captured and processed in real-time and the ultrasonic propagation can be visualized during scanning. The scanning speed can go up to 1.8 kHz for two-axis linear translation stage based B-UPIs and 10 kHz for galvanometer-based laser mirror scanners. In contrast with the other available ultrasound systems, these systems have the advantage of high-speed, non-contact, real-time, and non-destructive inspection. In this paper, the description of all bulk-wave ultrasonic imagers (B-UPIs) are presented and their advantages are discussed. Experiments are performed with these system on various structures to proof the integrity of their results. The C-scan results produced from non-dispersive, through-the-thickness, bulk-wave detection show good agreement in detection of structural variances and damage location in all inspected structures. These results show that bulk-wave UPIs can be used for in-situ NDE of engineering structures.

Optical frequency switching scheme for a high-speed broadband THz measurement system based on the photomixing technique.

PubMed

Song, Hajun; Hwang, Sejin; Song, Jong-In

2017-05-15

This study presents an optical frequency switching scheme for a high-speed broadband terahertz (THz) measurement system based on the photomixing technique. The proposed system can achieve high-speed broadband THz measurements using narrow optical frequency scanning of a tunable laser source combined with a wavelength-switchable laser source. In addition, this scheme can provide a larger output power of an individual THz signal compared with that of a multi-mode THz signal generated by multiple CW laser sources. A swept-source THz tomography system implemented with a two-channel wavelength-switchable laser source achieves a reduced time for acquisition of a point spread function and a higher depth resolution in the same amount of measurement time compared with a system with a single optical source.

Mass modeling for electrically powered space-based Yb:YAG lasers

NASA Astrophysics Data System (ADS)

Fitzgerald, Kevin F.; Leshner, Richard B.; Winsor, Harry V.

2000-05-01

An estimate for the mass of a nominal high-energy laser system envisioned for space applications is presented. The approach features a diode pumped solid state Yb:YAG laser. The laser specifications are10 MW average output power, and periods of up to 100 seconds continuous, full-power operation without refueling. The system is powered by lithium ion batteries, which are recharged by a solar array. The power requirements for this system dominate over any fixed structural features, so the critical issues in scaling a DPSSL to high power are made transparent. When based on currently available space qualified batteries, the design mass is about 500 metric tons. Therefore, innovations are required before high power electrical lasers will be serious contenders for use in space systems. The necessary innovations must improve the rate at which lithium ion batteries can output power. Masses for systems based on batteries that should be available in the near future are presented. This analysis also finds that heating of the solid state lasing material, cooling of the diode pump lasers and duty cycle are critical issues. Features dominating the thermal control requirements are the heat capacity of garnet, the operational temperature range of the system, and the required cooling time between periods of full operation. The duty cycle is a critical factor in determining both the mass of the diode array needed, and the mass of the power supply system.

NASA ground-based and space-based laser ranging systems

NASA Technical Reports Server (NTRS)

Fitzmaurice, M. W.

1978-01-01

Laser ranging is expected to help unlock the mysteries of the earthquake phenomenon by producing unique results of crustal motions of the Earth. The current state of the art and future projections are presented, including principal applications and characteristics of typical systems.

A digital intensity stabilization system for HeNe laser

NASA Astrophysics Data System (ADS)

Wei, Zhimeng; Lu, Guangfeng; Yang, Kaiyong; Long, Xingwu; Huang, Yun

2012-02-01

A digital intensity stabilization system for HeNe laser is developed. Based on a switching power IC to design laser power supply and a general purpose microcontroller to realize digital PID control, the system constructs a closed loop to stabilize the laser intensity by regulating its discharge current. The laser tube is made of glass ceramics and its integrated structure is steady enough to eliminate intensity fluctuations at high frequency and attenuates all intensity fluctuations, and this makes it easy to tune the control loop. The control loop between discharge current and photodiode voltage eliminates the long-term drifts. The intensity stability of the HeNe laser with this system is 0.014% over 12 h.

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.

An efficient solid modeling system based on a hand-held 3D laser scan device

NASA Astrophysics Data System (ADS)

Xiong, Hanwei; Xu, Jun; Xu, Chenxi; Pan, Ming

2014-12-01

The hand-held 3D laser scanner sold in the market is appealing for its port and convenient to use, but price is expensive. To develop such a system based cheap devices using the same principles as the commercial systems is impossible. In this paper, a simple hand-held 3D laser scanner is developed based on a volume reconstruction method using cheap devices. Unlike convenient laser scanner to collect point cloud of an object surface, the proposed method only scan few key profile curves on the surface. Planar section curve network can be generated from these profile curves to construct a volume model of the object. The details of design are presented, and illustrated by the example of a complex shaped object.

Soliton microcomb range measurement

NASA Astrophysics Data System (ADS)

Suh, Myoung-Gyun; Vahala, Kerry J.

2018-02-01

Laser-based range measurement systems are important in many application areas, including autonomous vehicles, robotics, manufacturing, formation flying of satellites, and basic science. Coherent laser ranging systems using dual-frequency combs provide an unprecedented combination of long range, high precision, and fast update rate. We report dual-comb distance measurement using chip-based soliton microcombs. A single pump laser was used to generate dual-frequency combs within a single microresonator as counterpropagating solitons. We demonstrated time-of-flight measurement with 200-nanometer precision at an averaging time of 500 milliseconds within a range ambiguity of 16 millimeters. Measurements at distances up to 25 meters with much lower precision were also performed. Our chip-based source is an important step toward miniature dual-comb laser ranging systems that are suitable for photonic integration.

Self-optimizing approach for automated laser resonator alignment

NASA Astrophysics Data System (ADS)

Brecher, C.; Schmitt, R.; Loosen, P.; Guerrero, V.; Pyschny, N.; Pavim, A.; Gatej, A.

2012-02-01

Nowadays, the assembly of laser systems is dominated by manual operations, involving elaborate alignment by means of adjustable mountings. From a competition perspective, the most challenging problem in laser source manufacturing is price pressure, a result of cost competition exerted mainly from Asia. From an economical point of view, an automated assembly of laser systems defines a better approach to produce more reliable units at lower cost. However, the step from today's manual solutions towards an automated assembly requires parallel developments regarding product design, automation equipment and assembly processes. This paper introduces briefly the idea of self-optimizing technical systems as a new approach towards highly flexible automation. Technically, the work focuses on the precision assembly of laser resonators, which is one of the final and most crucial assembly steps in terms of beam quality and laser power. The paper presents a new design approach for miniaturized laser systems and new automation concepts for a robot-based precision assembly, as well as passive and active alignment methods, which are based on a self-optimizing approach. Very promising results have already been achieved, considerably reducing the duration and complexity of the laser resonator assembly. These results as well as future development perspectives are discussed.

Remote Operations of Laser Guide Star Systems: Gemini Observatory.

NASA Astrophysics Data System (ADS)

Oram, Richard J.; Fesquet, Vincent; Wyman, Robert; D'Orgeville, Celine

2011-03-01

The Gemini North telescope, equipped with a 14W laser, has been providing Laser Guide Star Adaptive Optics (LGS AO) regular science queue observations for worldwide astronomers since February 2007. The new 55W laser system for MCAO was installed on the Gemini South telescope in May 2010. In this paper, we comment on how Gemini Observatory developed regular remote operation of the Laser Guide Star Facility and high-power solid-state laser as routine normal operations. Fully remote operation of the LGSF from the Hilo base facility HBF was initially trialed and then optimized and became the standard operating procedure (SOP) for LGS operation in December 2008. From an engineering perspective remote operation demands stable, well characterized and base-lined equipment sets. In the effort to produce consistent, stable and controlled laser parameters (power, wavelength and beam quality) we completed a failure mode effect analysis of the laser system and sub systems that initiated a campaign of hardware upgrades and procedural improvements to the routine maintenance operations. Finally, we provide an overview of normal operation procedures during LGS runs and present a snapshot of data accumulated over several years that describes the overall LGS AO observing efficiency at the Gemini North telescope.

Sub-pixel accuracy thickness calculation of poultry fillets from scattered laser profiles

NASA Astrophysics Data System (ADS)

Jing, Hansong; Chen, Xin; Tao, Yang; Zhu, Bin; Jin, Fenghua

2005-11-01

A laser range imaging system based on the triangulation method was designed and implemented for online high-resolution thickness calculation of poultry fillets. A laser pattern was projected onto the surface of the chicken fillet for calculation of the thickness of the meat. Because chicken fillets are relatively loosely-structured material, a laser light easily penetrates the meat, and scattering occurs both at and under the surface. When laser light is scattered under the surface it is reflected back and further blurs the laser line sharpness. To accurately calculate the thickness of the object, the light transportation has to be considered. In the system, the Bidirectional Reflectance Distribution Function (BSSRDF) was used to model the light transportation and the light pattern reflected into the cameras. BSSRDF gives the reflectance of a target as a function of illumination geometry and viewing geometry. Based on this function, an empirical method has been developed and it has been proven that this method can be used to accurately calculate the thickness of the object from a scattered laser profile. The laser range system is designed as a sub-system that complements the X-ray bone inspection system for non-invasive detection of hazardous materials in boneless poultry meat with irregular thickness.

KrF laser-induced OH fluorescence imaging in a supersonic combustion tunnel

NASA Technical Reports Server (NTRS)

Quagliaroli, T. M.; Laufer, G.; Hollo, S. D.; Krauss, R. H.; Whitehurst, R. B., III; Mcdaniel, J. C., Jr.

1992-01-01

Planar fluorescence images of OH in a continuous-flow, electrical-resistively heated, high enthalpy, hydrogen-air combustion tunnel, induced by a tunable KrF laser, were recorded. These images were compared to previously recorded fluorescence images induced by a doubled-dye laser under similar conditions. Images induced by the doubled-dye laser system demonstrated a severe distortion caused by absorption and fluorescence trapping. By contrast, images of the fluorescence induced by the tunable KrF laser retained the symmetry properties of the flow. Based on signal-to-noise ratio measurements the yield of the fluorescence induced by the doubled-dye laser is larger than the fluorescence yield induced by the KrF laser. The measurements in the present facility of OH fluorescence induced by the KrF laser were limited by the photon-statistical noise. Based 2 on this result, doubled-dye laser systems are recommended for OH imaging in small and OH lean (less than 10 exp 15/cu cm) facilities. KrF lasers should be selected otherwise.

Free-space laser communication technologies; Proceedings of the Meeting, Los Angeles, CA, Jan. 11, 12, 1988

NASA Astrophysics Data System (ADS)

Koepf, Gerhard A.; Begley, David L.

1988-01-01

The present conference discusses topics in free-space laser communications, laser link characteristics, satellite laser communication systems, optoelectronic components for laser communications, and space laser subsystem technologies. Attention is given to Space Station-based deep-space communication experiments, the application of intersatellite links to operational satellite systems, high-power 0.87 micron channel substrate planar lasers for spaceborne communications, a ground experiment using a CO2 laser transceiver for free-space communications, studies of laser ranging to the TOPEX satellite, diffraction-limited tracking for space communications, and the compact implementation of a real-time, acoustooptic SAR processor.

A new airborne laser rangefinder dynamic target simulator for non-stationary environment

NASA Astrophysics Data System (ADS)

Ma, Pengge; Pang, Dongdong; Yi, Yang

2017-11-01

For the non-stationary environment simulation in laser range finder product testing, a new dynamic target simulation system is studied. First of all, the three-pulsed laser ranging principle, laser target signal composition and mathematical representation are introduced. Then, the actual nonstationary working environment of laser range finder is analyzed, and points out that the real sunshine background light clutter and target shielding effect in laser echo become the main influencing factors. After that, the dynamic laser target signal simulation method is given. Eventlly, the implementation of automatic test system based on arbitrary waveform generator is described. Practical application shows that the new echo signal automatic test system can simulate the real laser ranging environment of laser range finder, and is suitable for performance test of products.

Polarized millijoule fiber laser system with high beam quality and pulse shaping ability

NASA Astrophysics Data System (ADS)

Zhang, Rui; Tian, Xiaocheng; Xu, Dangpeng; Zhou, Dandan; Zong, Zhaoyu; Li, Hongxun; Fan, Mengqiu; Huang, Zhihua; Zhu, Na; Su, Jingqin; Zhu, Qihua; Jing, Feng

2017-05-01

The coherent amplification network (CAN) aims at developing a laser system based on the coherent combination of multiple laser beams, which are produced through a network of high beam quality optical fiber amplifiers. The scalability of the CAN laser facilitates the development of many novel applications, such as fiber-based acceleration, orbital debris removal and inertial confinement fusion energy. According to the requirements of CAN and the front end of high-power laser facilities, a millijoule polarized fiber laser system was studied in this paper. Using polarization maintaining Ytterbium-fiber laser system as the seed, and 10-μm core Yb-doped fiber amplifier as the first power amplifier and 40-μm core polarizing (PZ) photonic crystal fiber (PCF) as the second power amplifier, the all-fiber laser system outputs 1.06-mJ energy at 10 ns and diffraction limited mode quality. Using 85-μm rod-type PCF as the third power amplifiers, 2.5-mJ energy at 10-ns pulse width was obtained with better than 500:1 peak-to-foot pulse shaping ability and fundamental mode beam quality. The energy fluctuation of the system is 1.3% rms with 1-mJ output in one hour. When using phase-modulated pulse as the seed, the frequency modulation to amplitude modulation (FM-to-AM) conversion ratio of the system is better than 5%. This fiber laser system has the advantages of high beam quality, high beam shaping ability, good stability, small volume and free of maintenance, which can be used in many applications.

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.

Output power stability of a HCN laser using a stepping motor for the EAST interferometer system

NASA Astrophysics Data System (ADS)

Zhang, J. B.; Wei, X. C.; Liu, H. Q.; Shen, J. J.; Zeng, L.; Jie, Y. X.

2015-11-01

The HCN laser on EAST is a continuous wave glow discharge laser with 3.4 m cavity length and 120 mW power output at 337 μ m wavelength. Without a temperature-controlled system, the cavity length of the laser is very sensitive to the environmental temperature. An external power feedback control system is applied on the HCN laser to stabilize the laser output power. The feedback system is composed of a stepping motor, a PLC, a supervisory computer, and the corresponding control program. One step distance of the stepping motor is 1 μ m and the time response is 0.5 s. Based on the power feedback control system, a stable discharge for the HCN laser is obtained more than eight hours, which satisfies the EAST experiment.

New laser system for highly sensitive clinical pulse oximetry

NASA Astrophysics Data System (ADS)

Hamza, Mostafa; Hamza, Mohammad

1996-04-01

This paper describes the theory and design of a new pulse oximeter in which laser diodes and other compact laser sources are used for the measurement of oxygen saturation in patients who are at risk of developing hypoxemia. The technique depends upon illuminating special sites of the skin of the patient with radiation from modulated laser sources at selected wavelengths. The specific laser wavelengths are chosen based on the absorption characteristics of oxyhemoglobin, reduced hemoglobin and other interfering sources for obtaining more accurate measurements. The laser radiation transmitted through the tissue is detected and signal processing based on differential absorption laser spectroscopy is done in such a way to overcome the primary performance limitations of the conventionally used pulse oximetry. The new laser pulse oximeter can detect weak signals and is not affected by other light sources such as surgical lamps, phototherapy units, etc. The detailed description and operating characteristics of this system are presented.

Laser-based optoelectronic system for therapy by medical treatment of cardiovascular diseases

NASA Astrophysics Data System (ADS)

Chtchoupak, Oleg S.; Shpilevoj, Boris N.; Zapaeva, Natlia L.

1996-01-01

The method and design of a system for the laser treatment of ischemic heart disease is presented. Our conceptual approach to the development of the system is based on the theoretical and experimental works of the east and west scientists about positive influence of low intensity laser irradiation in the near infrared range by treatment of cardiovascular diseases. The method and system allow active influence on the subepicardial collateral blood circulation with near infrared (NIR) laser irradiation in wavelength ranges of 0.86-1.06 mkm. The presented technique makes it possible to achieve a higher effectiveness of treatment due to individual choice of radiation parameters on the basis of analysis of the patient conditions before and after laser therapy and due to simultaneous affection at several points of the human body. Finally, results of the tests are presented, which prove given methods.

A tunable single-monochromator Raman system based on the supercontinuum laser and tunable filters for resonant Raman profile measurements.

PubMed

Liu, X-L; Liu, H-N; Tan, P-H

2017-08-01

Resonant Raman spectroscopy requires that the wavelength of the laser used is close to that of an electronic transition. A tunable laser source and a triple spectrometer are usually necessary for resonant Raman profile measurements. However, such a system is complex with low signal throughput, which limits its wide application by scientific community. Here, a tunable micro-Raman spectroscopy system based on the supercontinuum laser, transmission grating, tunable filters, and single-stage spectrometer is introduced to measure the resonant Raman profile. The supercontinuum laser in combination with transmission grating makes a tunable excitation source with a bandwidth of sub-nanometer. Such a system exhibits continuous excitation tunability and high signal throughput. Its good performance and flexible tunability are verified by resonant Raman profile measurement of twisted bilayer graphene, which demonstrates its potential application prospect for resonant Raman spectroscopy.

Development of laser transmission system

NASA Astrophysics Data System (ADS)

Song, Jiawu; Zhang, Yulan; Yang, Jiandong; Zhang, Xinming

1998-08-01

This paper discusses a light transfer system of therapeutic machine using carbon-dioxide laser. This system is based on imitating human being arm motion principle, consists of optical cardans mainly and can move in three-D space freely. Through it carbon-dioxide laser (which wavelength is 10.6 micrometer) is reflected, focused or diverged and transferred to the different therapeutic part of body to realize the purpose of cutting operation, gasification, cauterization and irradiation. This system includes an indicating system using He-Ne laser, by which carbon-dioxide laser can arrive therapeutic part accurately. This system possesses some advantages e.g. an accurate transfer, large moving range, small power consumption, high power density and easy operation. At present the occupancy in home market of this kind laser transfer system products is over 95%. Some products have been exported to other countries.

Photoluminescence-based quality control for thin film absorber layers of photovoltaic devices

DOEpatents

Repins, Ingrid L.; Kuciauskas, Darius

2015-07-07

A time-resolved photoluminescence-based system providing quality control during manufacture of thin film absorber layers for photovoltaic devices. The system includes a laser generating excitation beams and an optical fiber with an end used both for directing each excitation beam onto a thin film absorber layer and for collecting photoluminescence from the absorber layer. The system includes a processor determining a quality control parameter such as minority carrier lifetime of the thin film absorber layer based on the collected photoluminescence. In some implementations, the laser is a low power, pulsed diode laser having photon energy at least great enough to excite electron hole pairs in the thin film absorber layer. The scattered light may be filterable from the collected photoluminescence, and the system may include a dichroic beam splitter and a filter that transmit the photoluminescence and remove scattered laser light prior to delivery to a photodetector and a digital oscilloscope.

Laser Guidestar Satellite for Ground-based Adaptive Optics Imaging of Geosynchronous Satellites and Astronomical Targets

NASA Astrophysics Data System (ADS)

Marlow, W. A.; Cahoy, K.; Males, J.; Carlton, A.; Yoon, H.

2015-12-01

Real-time observation and monitoring of geostationary (GEO) satellites with ground-based imaging systems would be an attractive alternative to fielding high cost, long lead, space-based imagers, but ground-based observations are inherently limited by atmospheric turbulence. Adaptive optics (AO) systems are used to help ground telescopes achieve diffraction-limited seeing. AO systems have historically relied on the use of bright natural guide stars or laser guide stars projected on a layer of the upper atmosphere by ground laser systems. There are several challenges with this approach such as the sidereal motion of GEO objects relative to natural guide stars and limitations of ground-based laser guide stars; they cannot be used to correct tip-tilt, they are not point sources, and have finite angular sizes when detected at the receiver. There is a difference between the wavefront error measured using the guide star compared with the target due to cone effect, which also makes it difficult to use a distributed aperture system with a larger baseline to improve resolution. Inspired by previous concepts proposed by A.H. Greenaway, we present using a space-based laser guide starprojected from a satellite orbiting the Earth. We show that a nanosatellite-based guide star system meets the needs for imaging GEO objects using a low power laser even from 36,000 km altitude. Satellite guide star (SGS) systemswould be well above atmospheric turbulence and could provide a small angular size reference source. CubeSatsoffer inexpensive, frequent access to space at a fraction of the cost of traditional systems, and are now being deployed to geostationary orbits and on interplanetary trajectories. The fundamental CubeSat bus unit of 10 cm cubed can be combined in multiple units and offers a common form factor allowing for easy integration as secondary payloads on traditional launches and rapid testing of new technologies on-orbit. We describe a 6U CubeSat SGS measuring 10 cm x 20 cm x 30 cm with laser power on the order of milliwatts, and a commercial off the shelf based attitude determination and control system, among others. Different from standard 1U and 3U buses, the 6U form factor allows for a propulsion system for navigating around multiple targets in the GEO belt.

SU-F-J-44: Development of a Room Laser Based Real-Time Alignment Monitoring System Using An Array of Photodiodes

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

Noh, Y; Kim, T; Kang, S

2016-06-15

Purpose: To develop a real-time alignment monitoring system (RAMS) to compensate for the limitations of the conventional room laser based alignment system, and to verify the feasibility of the RAMS. Methods: The RAMS was composed of a room laser sensing array (RLSA), an analog-todigital converter, and a control PC. In the RLSA, seven photodiodes (each in 1 mm width) are arranged in a pattern that the RAMS provides alignment in 1 mm resolution. It works based on detecting laser light aligned on one of photodiodes. When misaligned, the laser would match with different photodiode(s) giving signal at unexpected location. Thus,more » how much displaced can be determined. To verify the reproducibility of the system with respect to time as well as repeated set-ups, temporal reproducibility and repeatability test was conducted. The accuracy of the system was tested by obtaining detection signals with varying laser-match positions. Results: The signal of the RAMS was found to be stable with respect to time. The repeatability test resulted in a maximum coefficient of variance of 1.14%, suggesting that the signal of the RAMS was stable over repeated set-ups. In the accuracy test, signals between when the laser was aligned and notaligned with any of sensors could be distinguished by signal intensity. The signals of not-aligned sensors were always below 75% of the signal of the aligned sensor. It was confirmed that the system could detect 1 mm of movement by monitoring the pattern of signals, and could observe the movement of the system in real-time. Conclusion: We developed a room laser based alignment monitoring system. The feasibility test verified that the system is capable of quantitative alignment monitoring in real time. The system is relatively simple, not expensive, and considered to be easily incorporated into conventional room laser systems for real-time alignment monitoring. This research was supported by the Mid-career Researcher Program through NRF funded by the Ministry of Science, ICT & Future Planning of Korea (NRF-2014R1A2A1A10050270) and by the Radiation Technology R&D program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (No. 2013M2A2A7038291)« less

Further investigation of surface velocity measurements for material characterization in laser shockwave experiments

NASA Astrophysics Data System (ADS)

Smith, James A.; Lacy, Jeffrey M.; Scott, Clark L.; Benefiel, Bradley C.; Lévesque, Daniel; Monchalin, Jean-Pierre; Lord, Martin

2018-04-01

As part of the U.S. High Performance Research Reactor program, a laser shock test system is being developed by the Idaho National Laboratory (INL) to characterize interface strength in innovative plate fuel for research reactors around the world. The INL has been working with National Research Council Canada (NRC) on this project for the last five years. One of the concerns is the difficulty of calibrating and standardizing the laser shock technique. A recent analytical study and testing support the use of the Hugoniot Elastic Limit (HEL) in materials as a robust and simple benchmark to compare stresses generated by different laser shock systems. Using a non-contact laser velocimeter based on a solid Fabry-Perot etalon, the systems at NRC and INL show that the back-surface velocity reached at the HEL is consistent, and independent of the laser power used. In this work, the laser velocimeter of the NRC system is tested against a fast rotating wheel to verify accuracy and determine best operating conditions. A round robin test between the two laser shock systems on plates of different aluminum alloys is presented that shows the consistent characterization of the aluminum alloys based on the HEL velocities as well as determines the bias between the systems. The effects of setup parameters on other characteristics of the back-surface velocity trace and corresponding stress wave are also discussed.

Study on a novel laser target detection system based on software radio technique

NASA Astrophysics Data System (ADS)

Song, Song; Deng, Jia-hao; Wang, Xue-tian; Gao, Zhen; Sun, Ji; Sun, Zhi-hui

2008-12-01

This paper presents that software radio technique is applied to laser target detection system with the pseudo-random code modulation. Based on the theory of software radio, the basic framework of the system, hardware platform, and the implementation of the software system are detailed. Also, the block diagram of the system, DSP circuit, block diagram of the pseudo-random code generator, and soft flow diagram of signal processing are designed. Experimental results have shown that the application of software radio technique provides a novel method to realize the modularization, miniaturization and intelligence of the laser target detection system, and the upgrade and improvement of the system will become simpler, more convenient, and cheaper.

Laser Development for Gravitational-Wave Interferometry in Space

NASA Technical Reports Server (NTRS)

Numata, Kenji; Camp, Jordan

2012-01-01

We are reporting on our development work on laser (master oscillator) and optical amplifier systems for gravitational-wave interferometry in space. Our system is based on the mature, wave-guided optics technologies, which have advantages over bulk, crystal-based, free-space optics. We are investing in a new type of compact, low-noise master oscillator, called the planar-waveguide external cavity diode laser. We made measurements, including those of noise, and performed space-qualification tests.

Perspectives of powerful laser technique for medicine

NASA Astrophysics Data System (ADS)

Konov, Vitali I.; Prokhorov, Alexander M.; Shcherbakov, Ivan A.

1991-11-01

The optimum laser-system parameters are being selected for several types of surgical operations using ablation techniques. The choice is based on the specific demands of the operation performed, knowledge of the ablation laws, limitations on laser-beam intensity which come from the necessity to transport high-intensity light through flexible fiber, and the peculiarities of different laser systems. At present it is more expedient to develop laser medical setups oriented to the solution of one task or a limited number of problems. The choice of a concrete installation should be based on the investigation results of interaction of radiation with biological tissues and its transmission through the fiber, the analysis of the level of development of laser and fiber technique, specificity of the operation, and compatibility of laser facilitates and traditional medical equipment. The paper illustrates such an approach by way of several concrete examples and notes the corresponding laser systems, which were developed or are in the developmental stage in the General Physics Institute of the USSR Academy of Sciences and in organizations connected with the Institute.

Low jitter RF distribution system

DOEpatents

Wilcox, Russell; Doolittle, Lawrence; Huang, Gang

2012-09-18

A timing signal distribution system includes an optical frequency stabilized laser signal amplitude modulated at an rf frequency. A transmitter box transmits a first portion of the laser signal and receive a modified optical signal, and outputs a second portion of the laser signal and a portion of the modified optical signal. A first optical fiber carries the first laser signal portion and the modified optical signal, and a second optical fiber carries the second portion of the laser signal and the returned modified optical signal. A receiver box receives the first laser signal portion, shifts the frequency of the first laser signal portion outputs the modified optical signal, and outputs an electrical signal on the basis of the laser signal. A detector at the end of the second optical fiber outputs a signal based on the modified optical signal. An optical delay sensing circuit outputs a data signal based on the detected modified optical signal. An rf phase detect and correct signal circuit outputs a signal corresponding to a phase stabilized rf signal based on the data signal and the frequency received from the receiver box.

Stabilizing operation point technique based on the tunable distributed feedback laser for interferometric sensors

NASA Astrophysics Data System (ADS)

Mao, Xuefeng; Zhou, Xinlei; Yu, Qingxu

2016-02-01

We describe a stabilizing operation point technique based on the tunable Distributed Feedback (DFB) laser for quadrature demodulation of interferometric sensors. By introducing automatic lock quadrature point and wavelength periodically tuning compensation into an interferometric system, the operation point of interferometric system is stabilized when the system suffers various environmental perturbations. To demonstrate the feasibility of this stabilizing operation point technique, experiments have been performed using a tunable-DFB-laser as light source to interrogate an extrinsic Fabry-Perot interferometric vibration sensor and a diaphragm-based acoustic sensor. Experimental results show that good tracing of Q-point was effectively realized.

Laser focal profiler based on forward scattering of a nanoparticle

NASA Astrophysics Data System (ADS)

Ota, Taisuke

2018-03-01

A laser focal intensity profiling method based on the forward scattering from a nanoparticle is demonstrated for in situ measurements using a laser focusing system with six microscope objective lenses with different numerical apertures ranging from 0.15 to 1.4. The measured profiles showed Airy disc patterns although their rings showed some imperfections due to aberrations and misalignment of the test system. The dipole radiation model revealed that the artefact of this method was much smaller than the influence of the deterioration in the experimental system; a condition where no artefact appears was predicted based on proper selection of measurement angles.

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.

Neural network approximation of nonlinearity in laser nano-metrology system based on TLMI

NASA Astrophysics Data System (ADS)

Olyaee, Saeed; Hamedi, Samaneh

2011-02-01

In this paper, an approach based on neural network (NN) for nonlinearity modeling in a nano-metrology system using three-longitudinal-mode laser heterodyne interferometer (TLMI) for length and displacement measurements is presented. We model nonlinearity errors that arise from elliptically and non-orthogonally polarized laser beams, rotational error in the alignment of laser head with respect to the polarizing beam splitter, rotational error in the alignment of the mixing polarizer, and unequal transmission coefficients in the polarizing beam splitter. Here we use a neural network algorithm based on the multi-layer perceptron (MLP) network. The simulation results show that multi-layer feed forward perceptron network is successfully applicable to real noisy interferometer signals.

Blue laser system for photo-dynamic therapy

NASA Astrophysics Data System (ADS)

Dabu, R.; Carstocea, B.; Blanaru, C.; Pacala, O.; Stratan, A.; Ursu, D.; Stegaru, F.

2007-03-01

A blue laser system for eye diseases (age related macular degeneration, sub-retinal neo-vascularisation in myopia and presumed ocular histoplasmosis syndrome - POHS) photo-dynamic therapy, based on riboflavin as photosensitive substance, has been developed. A CW diode laser at 445 nm wavelength was coupled through an opto-mechanical system to the viewing path of a bio-microscope. The laser beam power in the irradiated area is adjustable between 1 mW and 40 mW, in a spot of 3-5 mm diameter. The irradiation time can be programmed in the range of 1-19 minutes. Currently, the laser system is under clinic tests.

Laser beam riding guided system principle and design research

NASA Astrophysics Data System (ADS)

Qu, Zhou; Jin, Yi; Xu, Zhou; Xing, Hao

2016-01-01

With the development of science and technology, precision-strike weapons has been considered to be important for winning victory in military field. Laser guidance is a major method to execute precision-strike in modern warfare. At present, the problems of primary stage of Laser guidance has been solved with endeavors of countries. Several technical aspects of laser-beam riding guided system have been mature, such as atmosphere penetration of laser beam, clutter inhibition on ground, laser irradiator, encoding and decoding of laser beam. Further, laser beam quality, equal output power and atmospheric transmission properties are qualified for warfare situation. Riding guidance instrument is a crucial element of Laser-beam riding guided system, and is also a vital element of airborne, vehicle-mounted and individual weapon. The optical system mainly consist of sighting module and laser-beam guided module. Photoelectric detector is the most important sensing device of seeker, and also the key to acquire the coordinate information of target space. Currently, in consideration of the 1.06 u m of wavelength applied in all the semi-active laser guided weapons systems, lithium drifting silicon photodiode which is sensitive to 1.06 u m of wavelength is used in photoelectric detector. Compared to Solid and gas laser, diode laser has many merits such as small volume, simple construction, light weight, long life, low lost and easy modulation. This article introduced the composition and operating principle of Laser-beam riding guided system based on 980 nm diode laser, and made a analysis of key technology; for instance, laser irradiator, modulating disk of component, laser zooming system. Through the use of laser diode, Laser-beam riding guided system is likely to have smaller shape and very light.

Transcranial infrared laser stimulation improves rule-based, but not information-integration, category learning in humans.

PubMed

Blanco, Nathaniel J; Saucedo, Celeste L; Gonzalez-Lima, F

2017-03-01

This is the first randomized, controlled study comparing the cognitive effects of transcranial laser stimulation on category learning tasks. Transcranial infrared laser stimulation is a new non-invasive form of brain stimulation that shows promise for wide-ranging experimental and neuropsychological applications. It involves using infrared laser to enhance cerebral oxygenation and energy metabolism through upregulation of the respiratory enzyme cytochrome oxidase, the primary infrared photon acceptor in cells. Previous research found that transcranial infrared laser stimulation aimed at the prefrontal cortex can improve sustained attention, short-term memory, and executive function. In this study, we directly investigated the influence of transcranial infrared laser stimulation on two neurobiologically dissociable systems of category learning: a prefrontal cortex mediated reflective system that learns categories using explicit rules, and a striatally mediated reflexive learning system that forms gradual stimulus-response associations. Participants (n=118) received either active infrared laser to the lateral prefrontal cortex or sham (placebo) stimulation, and then learned one of two category structures-a rule-based structure optimally learned by the reflective system, or an information-integration structure optimally learned by the reflexive system. We found that prefrontal rule-based learning was substantially improved following transcranial infrared laser stimulation as compared to placebo (treatment X block interaction: F(1, 298)=5.117, p=0.024), while information-integration learning did not show significant group differences (treatment X block interaction: F(1, 288)=1.633, p=0.202). These results highlight the exciting potential of transcranial infrared laser stimulation for cognitive enhancement and provide insight into the neurobiological underpinnings of category learning. Copyright © 2017 Elsevier Inc. All rights reserved.

Research and Development of Laser Diode Based Instruments for Applications in Space

NASA Technical Reports Server (NTRS)

Krainak, Michael; Abshire, James; Cornwell, Donald; Dragic, Peter; Duerksen, Gary; Switzer, Gregg

1999-01-01

Laser diode technology continues to advance at a very rapid rate due to commercial applications such as telecommunications and data storage. The advantages of laser diodes include, wide diversity of wavelengths, high efficiency, small size and weight and high reliability. Semiconductor and fiber optical-amplifiers permit efficient, high power master oscillator power amplifier (MOPA) transmitter systems. Laser diode systems which incorporate monolithic or discrete (fiber optic) gratings permit single frequency operation. We describe experimental and theoretical results of laser diode based instruments currently under development at NASA Goddard Space Flight Center including miniature lidars for measuring clouds and aerosols, water vapor and wind for Earth and planetary (Mars Lander) use.

Highly stable multi-wavelength erbium-doped fiber linear laser based on modal interference

NASA Astrophysics Data System (ADS)

Herrera-Piad, L. A.; Jauregui-Vazquez, D.; Lopez-Dieguez, Y.; Estudillo-Ayala, J. M.; Hernandez-Garcia, J. C.; Sierra-Hernandez, J. M.; Bianchetti, M.; Rojas-Laguna, R.

2018-03-01

We report a linear fiber laser cavity based on an all-fiber Fabry-Perot interferometer and bi-tapered optical fiber for multi-wavelength emission generation. Curvature and strain are used to operate the laser system and the number of lines as well, the emission regions are stronger related to the physical effect applied, due to the phase alteration between the multiple fiber optic modes involved. The original laser emissions present zero wavelength variations, minimal power fluctuations and small spacing mode (1 nm). Additionally, a nonlinear fiber was employed trying to improve the performance of the multiple lasing lines. This system offers a low implementation cost, compactness and good laser parameters.

Laser application in neurosurgery

PubMed Central

Belykh, Evgenii; Yagmurlu, Kaan; Martirosyan, Nikolay L.; Lei, Ting; Izadyyazdanabadi, Mohammadhassan; Malik, Kashif M.; Byvaltsev, Vadim A.; Nakaji, Peter; Preul, Mark C.

2017-01-01

Background: Technological innovations based on light amplification created by stimulated emission of radiation (LASER) have been used extensively in the field of neurosurgery. Methods: We reviewed the medical literature to identify current laser-based technological applications for surgical, diagnostic, and therapeutic uses in neurosurgery. Results: Surgical applications of laser technology reported in the literature include percutaneous laser ablation of brain tissue, the use of surgical lasers in open and endoscopic cranial surgeries, laser-assisted microanastomosis, and photodynamic therapy for brain tumors. Laser systems are also used for intervertebral disk degeneration treatment, therapeutic applications of laser energy for transcranial laser therapy and nerve regeneration, and novel diagnostic laser-based technologies (e.g., laser scanning endomicroscopy and Raman spectroscopy) that are used for interrogation of pathological tissue. Conclusion: Despite controversy over the use of lasers for treatment, the surgical application of lasers for minimally invasive procedures shows promising results and merits further investigation. Laser-based microscopy imaging devices have been developed and miniaturized to be used intraoperatively for rapid pathological diagnosis. The multitude of ways that lasers are used in neurosurgery and in related neuroclinical situations is a testament to the technological advancements and practicality of laser science. PMID:29204309

Design and Performance of a Miniature Lidar Wind Profiler (MLWP)

NASA Technical Reports Server (NTRS)

Cornwell, Donald M., Jr.; Miodek, Mariusz J.

1998-01-01

The directional velocity of the wind is one of the most critical components for understanding meteorological and other dynamic atmospheric processes. Altitude-resolved wind velocity measurements, also known as wind profiles or soundings, are especially necessary for providing data for meteorological forecasting and overall global circulation models (GCM's). Wind profiler data are also critical in identifying possible dangerous weather conditions for aviation. Furthermore, a system has yet to be developed for wind profiling from the surface of Mars which could also meet the stringent requirements on size, weight, and power of such a mission. Obviously, a novel wind profiling approach based on small and efficient technology is required to meet these needs. A lidar system based on small and highly efficient semiconductor lasers is now feasible due to recent developments in the laser and detector technologies. The recent development of high detection efficiency (50%), silicon-based photon-counting detectors when combined with high laser pulse repetition rates and long receiver integration times has allowed these transmitter energies to be reduced to the order of microjoules per pulse. Aerosol lidar systems using this technique have been demonstrated for both Q-switched, diode-pumped solid-state laser transmitters (lambda = 523 nm) and semiconductor diode lasers (lambda = 830 nm); however, a wind profiling lidar based on this technique has yet to be developed. We will present an investigation of a semiconductor-laser-based lidar system which uses the "edge-filter" direct detection technique to infer Doppler frequency shifts of signals backscattered from aerosols in the planetary boundary layer (PBL). Our investigation will incorporate a novel semiconductor laser design which mitigates the deleterious effects of frequency chirp in pulsed diode lasers, a problem which has limited their use in such systems in the past. Our miniature lidar could be used on a future Mars lander and perhaps find its own niche in terrestrial applications due to its potential low cost an small size.

Design of an infrared camera based aircraft detection system for laser guide star installations

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

Friedman, H.; Macintosh, B.

1996-03-05

There have been incidents in which the irradiance resulting from laser guide stars have temporarily blinded pilots or passengers of aircraft. An aircraft detection system based on passive near infrared cameras (instead of active radar) is described in this report.

Laser propulsion for orbit transfer - Laser technology issues

NASA Technical Reports Server (NTRS)

Horvath, J. C.; Frisbee, R. H.

1985-01-01

Using reasonable near-term mission traffic models (1991-2000 being the assumed operational time of the system) and the most current unclassified laser and laser thruster information available, it was found that space-based laser propulsion orbit transfer vehicles (OTVs) can outperform the aerobraked chemical OTV over a 10-year life-cycle. The conservative traffic models used resulted in an optimum laser power of about 1 MW per laser. This is significantly lower than the power levels considered in other studies. Trip time was taken into account only to the extent that the system was sized to accomplish the mission schedule.

Receiver design, performance analysis, and evaluation for space-borne laser altimeters and space-to-space laser ranging systems

NASA Technical Reports Server (NTRS)

Davidson, Frederic M.; Sun, Xiaoli; Field, Christopher T.

1995-01-01

This Interim report consists of a manuscript, 'Receiver Design for Satellite to Satellite Laser Ranging Instrument,' and copies of two papers we co-authored, 'Demonstration of High Sensitivity Laser Ranging System' and 'Semiconductor Laser-Based Ranging Instrument for Earth Gravity Measurements. ' These two papers were presented at the conference Semiconductor Lasers, Advanced Devices and Applications, August 21 -23, 1995, Keystone Colorado. The manuscript is a draft in the preparation for publication, which summarizes the theory we developed on space-borne laser ranging instrument for gravity measurements.

Phase-sensitive optical coherence tomography-based vibrometry using a highly phase-stable akinetic swept laser source

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

Applegate, Brian E.; Park, Jesung; Carbajal, Esteban

Phase-sensitive Optical Coherence Tomography (PhOCT) is an emerging tool for in vivo investigation of the vibratory function of the intact middle and inner ear. PhOCT is able to resolve micron scale tissue morphology in three dimensions as well as measure picometer scale motion at each spatial position. Most PhOCT systems to date have relied upon the phase stability offered by spectrometer detection. On the other hand swept laser source based PhOCT offers a number of advantages including balanced detection, long imaging depths, and high imaging speeds. Unfortunately the inherent phase instability of traditional swept laser sources has necessitated complex usermore » developed hardware/software solutions to restore phase sensitivity. Here we present recent results using a prototype swept laser that overcomes these issues. The akinetic swept laser is electronically tuned and precisely controls sweeps without any mechanical movement, which results in high phase stability. We have developed an optical fiber based PhOCT system around the akinetic laser source that had a 1550 nm center wavelength and a sweep rate of 140 kHz. The stability of the system was measured to be 4.4 pm with a calibrated reflector, thus demonstrating near shot noise limited performance. Using this PhOCT system, we have acquired structural and vibratory measurements of the middle ear in a mouse model, post mortem. The quality of the results suggest that the akinetic laser source is a superior laser source for PhOCT with many advantages that greatly reduces the required complexity of the imaging system.« less

Laser frequency stabilization using a transfer interferometer

NASA Astrophysics Data System (ADS)

Jackson, Shira; Sawaoka, Hiromitsu; Bhatt, Nishant; Potnis, Shreyas; Vutha, Amar C.

2018-03-01

We present a laser frequency stabilization system that uses a transfer interferometer to stabilize slave lasers to a reference laser. Our implementation uses off-the-shelf optical components along with microcontroller-based digital feedback, and offers a simple, flexible, and robust way to stabilize multiple laser frequencies to better than 1 MHz.

Automatic control system of high precision welding of workpieces in mechanical engineering

NASA Astrophysics Data System (ADS)

Kuznetsov, I. N.; Zvezdin, V. V.; Israfilov, I. H.; Portnov, S. M.

2014-12-01

In this paper, based on the conducted patent research, the system of laser welding control with different geometry of weld and shapes of parts is developed. The method of monitoring the position of the spot of laser radiation in relation to the curved weld is worked out; it is based on the tracking the edges of the welded parts by low-power laser radiation reflected from the surface of the parts. It allows to make the positioning of the focus of laser radiation in relation to the juncture of the welded parts automatically.

Advanced space power and propulsion based on lasers

NASA Astrophysics Data System (ADS)

Roth, M.; Logan, B. G.

2015-10-01

One of the key components for future space exploration, manned or unmanned, is the availability of propulsion systems beyond the state of the art. The rapid development in conventional propulsion systems since the middle of the 20th century has already reached the limits of chemical propulsion technology. To enhance mission radius, shorten the transit time and also extend the lifetime of a spacecraft more efficient, but still powerful propulsion system must be developed. Apart from the propulsion system a major weight contribution arises from the required energy source. Envisioning rapid development of future high average power laser systems and especially the ICAN project we review the prospect of advanced space propulsion based on laser systems.

Laser-based firing systems for prompt initiation of secondary explosives

NASA Technical Reports Server (NTRS)

Meeks, Kent D.; Setchell, Robert E.

1993-01-01

Motivated by issues of weapon safety and security, laser based firing systems for promptly initiating secondary explosives have been under active development at Sandia National Laboratories for more than four years. Such a firing system consists of miniaturized, Q-switched, solid-state laser, optical detonators, optical safety switches, and elements for splitting, coupling, and transmitting the laser output. Potential system applications pose significant challenges in terms of server mechanical and thermal environments and packaging constraints, while requiring clear demonstration of safety enhancements. The Direct Optical Initiation (DOI) Program at Sandia is addressing these challenges through progress development phases during which the design, fabrication, and testing of prototype hardware is aimed at more difficult application requirements. A brief history of the development program, and a summary of current and planned activities, will be presented.

Research on correction algorithm of laser positioning system based on four quadrant detector

NASA Astrophysics Data System (ADS)

Gao, Qingsong; Meng, Xiangyong; Qian, Weixian; Cai, Guixia

2018-02-01

This paper first introduces the basic principle of the four quadrant detector, and a set of laser positioning experiment system is built based on the four quadrant detector. Four quadrant laser positioning system in the actual application, not only exist interference of background light and detector dark current noise, and the influence of random noise, system stability, spot equivalent error can't be ignored, so it is very important to system calibration and correction. This paper analyzes the various factors of system positioning error, and then propose an algorithm for correcting the system error, the results of simulation and experiment show that the modified algorithm can improve the effect of system error on positioning and improve the positioning accuracy.

Modelling and control for laser based welding processes: modern methods of process control to improve quality of laser-based joining methods

NASA Astrophysics Data System (ADS)

Zäh, Ralf-Kilian; Mosbach, Benedikt; Hollwich, Jan; Faupel, Benedikt

2017-02-01

To ensure the competitiveness of manufacturing companies it is indispensable to optimize their manufacturing processes. Slight variations of process parameters and machine settings have only marginally effects on the product quality. Therefore, the largest possible editing window is required. Such parameters are, for example, the movement of the laser beam across the component for the laser keyhole welding. That`s why it is necessary to keep the formation of welding seams within specified limits. Therefore, the quality of laser welding processes is ensured, by using post-process methods, like ultrasonic inspection, or special in-process methods. These in-process systems only achieve a simple evaluation which shows whether the weld seam is acceptable or not. Furthermore, in-process systems use no feedback for changing the control variables such as speed of the laser or adjustment of laser power. In this paper the research group presents current results of the research field of Online Monitoring, Online Controlling and Model predictive controlling in laser welding processes to increase the product quality. To record the characteristics of the welding process, tested online methods are used during the process. Based on the measurement data, a state space model is ascertained, which includes all the control variables of the system. Depending on simulation tools the model predictive controller (MPC) is designed for the model and integrated into an NI-Real-Time-System.

Robust remote-pumping sodium laser for advanced LIDAR and guide star applications

NASA Astrophysics Data System (ADS)

Ernstberger, Bernhard; Enderlein, Martin; Friedenauer, Axel; Schwerdt, Robin; Wei, Daoping; Karpov, Vladimir; Leisching, Patrick; Clements, Wallace R. L.; Kaenders, Wilhelm G.

2015-10-01

The performance of large ground-based optical telescopes is limited due to wavefront distortions induced by atmospheric turbulence. Adaptive optics systems using natural guide stars with sufficient brightness provide a practical way for correcting the wavefront errors by means of deformable mirrors. Unfortunately, the sky coverage of bright stars is poor and therefore the concept of laser guide stars was invented, creating an artificial star by exciting resonance fluorescence from the mesospheric sodium layer about 90 km above the earth's surface. Until now, mainly dye lasers or sumfrequency mixing of solid state lasers were used to generate laser guide stars. However, these kinds of lasers require a stationary laser clean room for operation and are extremely demanding in maintenance. Under a development contract with the European Southern Observatory (ESO) and W. M. Keck Observatory (WMKO), TOPTICA Photonics AG and its partner MPB Communications have finalized the development of a next-generation sodium guide star laser system which is available now as a commercial off-the-shelf product. The laser is based on a narrow-band diode laser, Raman fiber amplifier (RFA) technology and resonant second-harmonic generation (SHG), thus highly reliable and simple to operate and maintain. It emits > 22 W of narrow-linewidth (≈ 5 MHz) continuous-wave radiation at sodium resonance and includes a re-pumping scheme for boosting sodium return flux. Due to the SHG resonator acting as spatial mode filter and polarizer, the output is diffraction-limited with RMS wavefront error < λ/25. Apart from this unique optical design, a major effort has been dedicated to integrating all optical components into a ruggedized system, providing a maximum of convenience and reliability for telescope operators. The new remote-pumping architecture allows for a large spatial separation between the main part of the laser and the compact laser head. Together with a cooling-water flow of less than 5 l/min and an overall power consumption of < 700 W, the system offers a maximum of flexibility with minimal infrastructure demands on site. Each system is built in a modular way, based on the concept of line-replaceable units (LRU). A comprehensive system software, as well as an intuitive service GUI, allow for remote control and error tracking down to at least the LRU level. In case of a failure, any LRU can be easily replaced. With these fiber-based guide star lasers, TOPTICA for the first time offers a fully engineered, off-the-shelf guide star laser system for groundbased optical telescopes providing convenient, turn-key operation in remote and harsh locations. Reliability and flexibility will be beneficial in particular for advanced satellite and space debris tracking as well as LIDAR applications.

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.

Modern retinal laser therapy

PubMed Central

Kozak, Igor; Luttrull, Jeffrey K.

2014-01-01

Medicinal lasers are a standard source of light to produce retinal tissue photocoagulation to treat retinovascular disease. The Diabetic Retinopathy Study and the Early Treatment Diabetic Retinopathy Study were large randomized clinical trials that have shown beneficial effect of retinal laser photocoagulation in diabetic retinopathy and have dictated the standard of care for decades. However, current treatment protocols undergo modifications. Types of lasers used in treatment of retinal diseases include argon, diode, dye and multicolor lasers, micropulse lasers and lasers for photodynamic therapy. Delivery systems include contact lens slit-lamp laser delivery, indirect ophthalmocope based laser photocoagulation and camera based navigated retinal photocoagulation with retinal eye-tracking. Selective targeted photocoagulation could be a future alternative to panretinal photocoagulation. PMID:25892934

Construction and Calibration of a Difference Frequency Laser Spectrometer and New THZ Frequency Measurements of water and Ammonia

NASA Technical Reports Server (NTRS)

Pearson, J. C.; Pickett, Herbert M.; Chen, Pin; Matsuura, Shuji; Blake, Geoffry A.

1999-01-01

A three laser system based on 852nm DBR lasers has been constructed and used to generate radiation in the 750 GHz to 1600 GHz frequency region. The system works by locking two of the three lasers to modes of an ultra low expansion Fabry-Perot cavity. The third laser is offset locked to one of the cavity locked lasers with conventional microwave techniques. The signal from the offset laser and the other cavity locked laser are injected into a Master Oscillator Power Amplifier (MOPA), amplified and focused on a low temperature grown GaAs photomixer, which radiates the difference frequency. The system has been calibrated with molecular lines to better than one part in 10(exp 7). In this paper we present the application of this system to the v(sub 2) in inversion band of Ammonia and the ground and v(sub 2) states of water. A discussion of the system design, the calibration and the new spectral measurements will be presented.

Research on Measurement Accuracy of Laser Tracking System Based on Spherical Mirror with Rotation Errors of Gimbal Mount Axes

NASA Astrophysics Data System (ADS)

Shi, Zhaoyao; Song, Huixu; Chen, Hongfang; Sun, Yanqiang

2018-02-01

This paper presents a novel experimental approach for confirming that spherical mirror of a laser tracking system can reduce the influences of rotation errors of gimbal mount axes on the measurement accuracy. By simplifying the optical system model of laser tracking system based on spherical mirror, we can easily extract the laser ranging measurement error caused by rotation errors of gimbal mount axes with the positions of spherical mirror, biconvex lens, cat's eye reflector, and measuring beam. The motions of polarization beam splitter and biconvex lens along the optical axis and vertical direction of optical axis are driven by error motions of gimbal mount axes. In order to simplify the experimental process, the motion of biconvex lens is substituted by the motion of spherical mirror according to the principle of relative motion. The laser ranging measurement error caused by the rotation errors of gimbal mount axes could be recorded in the readings of laser interferometer. The experimental results showed that the laser ranging measurement error caused by rotation errors was less than 0.1 μm if radial error motion and axial error motion were within ±10 μm. The experimental method simplified the experimental procedure and the spherical mirror could reduce the influences of rotation errors of gimbal mount axes on the measurement accuracy of the laser tracking system.

The network and transmission of based on the principle of laser multipoint communication

NASA Astrophysics Data System (ADS)

Fu, Qiang; Liu, Xianzhu; Jiang, Huilin; Hu, Yuan; Jiang, Lun

2014-11-01

Space laser communication is the perfectly choose to the earth integrated information backbone network in the future. This paper introduces the structure of the earth integrated information network that is a large capacity integrated high-speed broadband information network, a variety of communications platforms were densely interconnected together, such as the land, sea, air and deep air users or aircraft, the technologies of the intelligent high-speed processing, switching and routing were adopt. According to the principle of maximum effective comprehensive utilization of information resources, get accurately information, fast processing and efficient transmission through inter-satellite, satellite earth, sky and ground station and other links. Namely it will be a space-based, air-based and ground-based integrated information network. It will be started from the trends of laser communication. The current situation of laser multi-point communications were expounded, the transmission scheme of the dynamic multi-point between wireless laser communication n network has been carefully studied, a variety of laser communication network transmission schemes the corresponding characteristics and scope described in detail , described the optical multiplexer machine that based on the multiport form of communication is applied to relay backbone link; the optical multiplexer-based on the form of the segmentation receiver field of view is applied to small angle link, the optical multiplexer-based form of three concentric spheres structure is applied to short distances, motorized occasions, and the multi-point stitching structure based on the rotation paraboloid is applied to inter-satellite communications in detail. The multi-point laser communication terminal apparatus consist of the transmitting and receiving antenna, a relay optical system, the spectroscopic system, communication system and communication receiver transmitter system. The communication forms of optical multiplexer more than four goals or more, the ratio of received power and volume weight will be Obvious advantages, and can track multiple moving targets in flexible.It would to provide reference for the construction of earth integrated information networks.

Laser sensor system documentation.

DOT National Transportation Integrated Search

2017-03-01

Phase 1 of TxDOT Project 0-6873, True Road Surface Deflection Measuring Device, developed a : laser sensor system based on several sensors mounted on a rigid beam. : This sensor system remains with CTR currently, as the project is moving into Phase 2...

Tunable Laser Development for In-flight Fiber Optic Based Structural Health Monitoring Systems

NASA Technical Reports Server (NTRS)

Richards, Lance; Parker, Allen; Chan, Patrick

2014-01-01

The objective of this task is to investigate, develop, and demonstrate a low-cost swept lasing light source for NASA DFRC's fiber optics sensing system (FOSS) to perform structural health monitoring on current and future aerospace vehicles. This is the regular update of the Tunable Laser Development for In-flight Fiber Optic Based Structural Health Monitoring Systems website.

High-energy ultra-short pulse thin-disk lasers: new developments and applications

NASA Astrophysics Data System (ADS)

Michel, Knut; Klingebiel, Sandro; Schultze, Marcel; Tesseit, Catherine Y.; Bessing, Robert; Häfner, Matthias; Prinz, Stefan; Sutter, Dirk; Metzger, Thomas

2016-03-01

We report on the latest developments at TRUMPF Scientific Lasers in the field of ultra-short pulse lasers with highest output energies and powers. All systems are based on the mature and industrialized thin-disk technology of TRUMPF. Thin Yb:YAG disks provide a reliable and efficient solution for power and energy scaling to Joule- and kW-class picosecond laser systems. Due to its efficient one dimensional heat removal, the thin-disk exhibits low distortions and thermal lensing even when pumped under extremely high pump power densities of 10kW/cm². Currently TRUMPF Scientific Lasers develops regenerative amplifiers with highest average powers, optical parametric amplifiers and synchronization schemes. The first few-ps kHz multi-mJ thin-disk regenerative amplifier based on the TRUMPF thindisk technology was developed at the LMU Munich in 20081. Since the average power and energy have continuously been increased, reaching more than 300W (10kHz repetition rate) and 200mJ (1kHz repetition rate) at pulse durations below 2ps. First experiments have shown that the current thin-disk technology supports ultra-short pulse laser solutions >1kW of average power. Based on few-picosecond thin-disk regenerative amplifiers few-cycle optical parametric chirped pulse amplifiers (OPCPA) can be realized. These systems have proven to be the only method for scaling few-cycle pulses to the multi-mJ energy level. OPA based few-cycle systems will allow for many applications such as attosecond spectroscopy, THz spectroscopy and imaging, laser wake field acceleration, table-top few-fs accelerators and laser-driven coherent X-ray undulator sources. Furthermore, high-energy picosecond sources can directly be used for a variety of applications such as X-ray generation or in atmospheric research.

Optical communication in free space

NASA Technical Reports Server (NTRS)

Plotkin, H. H.; Mcavoy, N.; Fitzmaurice, M. W.

1974-01-01

Two classes of laser communication systems for handling very high data rates across inter-satellite distances are considered that provide for high antenna gains, wide modulation bandwidths, and optical receiver sensitivities. System design considerations are based upon the carbon dioxide laser modulation to accommodate digital or analog information, and the neodymium doped YAG laser pulse for digital modulation.

The generation of amplified spontaneous emission in high-power CPA laser systems.

PubMed

Keppler, Sebastian; Sävert, Alexander; Körner, Jörg; Hornung, Marco; Liebetrau, Hartmut; Hein, Joachim; Kaluza, Malte Christoph

2016-03-01

An analytical model is presented describing the temporal intensity contrast determined by amplified spontaneous emission in high-intensity laser systems which are based on the principle of chirped pulse amplification. The model describes both the generation and the amplification of the amplified spontaneous emission for each type of laser amplifier. This model is applied to different solid state laser materials which can support the amplification of pulse durations ≤350 fs . The results are compared to intensity and fluence thresholds, e.g. determined by damage thresholds of a certain target material to be used in high-intensity applications. This allows determining if additional means for contrast improvement, e.g. plasma mirrors, are required for a certain type of laser system and application. Using this model, the requirements for an optimized high-contrast front-end design are derived regarding the necessary contrast improvement and the amplified "clean" output energy for a desired focussed peak intensity. Finally, the model is compared to measurements at three different high-intensity laser systems based on Ti:Sapphire and Yb:glass. These measurements show an excellent agreement with the model.

Laser System for Photoelectron and X-Ray Production in the PLEIADES Compton Light Source

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

Gibson, D J; Barty, C J; Betts, S M

2005-04-21

The PLEIADES (Picosecond Laser-Electron Interaction for the Dynamic Evaluation of Structures) facility provides tunable short x-ray pulses with energies of 30-140 keV and pulse durations of 0.3-5 ps by scattering an intense, ultrashort laser pulse off a 35-75 MeV electron beam. Synchronization of the laser and electron beam is obtained by using a photoinjector gun, and using the same laser system to generate the electrons and the scattering laser. The Ti Ti:Sapphire, chirped pulse amplification based 500 mJ, 50 fs, 810 nm scattering laser and the similar 300 {micro}J, 5 ps, 266 nm photoinjector laser systems are detailed. Additionally, anmore » optical parametric chirped pulse amplification (OPCPA) system is studied as a replacement for part of the scattering laser front end. Such a change would significantly simplify the set-up the laser system by removing the need for active switching optics, as well as increase the pre-pulse contrast ratio which will be important when part of the scattering laser is used as a pump beam in pump-probe diffraction experiments using the ultrashort tunable x-rays generated as the probe.« less

Comparative hazard evaluation of near-infrared diode lasers.

PubMed

Marshall, W J

1994-05-01

Hazard evaluation methods from various laser protection standards differ when applied to extended-source, near-infrared lasers. By way of example, various hazard analyses are applied to laser training systems, which incorporate diode lasers, specifically those that assist in training military or law enforcement personnel in the proper use of weapons by simulating actual firing by the substitution of a beam of near-infrared energy for bullets. A correct hazard evaluation of these lasers is necessary since simulators are designed to be directed toward personnel during normal use. The differences among laser standards are most apparent when determining the hazard class of a laser. Hazard classification is based on a comparison of the potential exposures with the maximum permissible exposures in the 1986 and 1993 versions of the American National Standard for the Safe Use of Lasers, Z136.1, and the accessible emission limits of the federal laser product performance standard. Necessary safety design features of a particular system depend on the hazard class. The ANSI Z136.1-1993 standard provides a simpler and more accurate hazard assessment of low-power, near-infrared, diode laser systems than the 1986 ANSI standard. Although a specific system is evaluated, the techniques described can be readily applied to other near-infrared lasers or laser training systems.

Development of a mobile system based on laser-induced breakdown spectroscopy and dedicated to in situ analysis of polluted soils

NASA Astrophysics Data System (ADS)

Bousquet, B.; Travaillé, G.; Ismaël, A.; Canioni, L.; Michel-Le Pierrès, K.; Brasseur, E.; Roy, S.; le Hecho, I.; Larregieu, M.; Tellier, S.; Potin-Gautier, M.; Boriachon, T.; Wazen, P.; Diard, A.; Belbèze, S.

2008-10-01

Principal Components Analysis (PCA) is successfully applied to the full laser-induced breakdown spectroscopy (LIBS) spectra of soil samples, defining classes according to the concentrations of the major elements. The large variability of the LIBS data is related to the heterogeneity of the samples and the representativeness of the data is finally discussed. Then, the development of a mobile LIBS system dedicated to the in-situ analysis of soils polluted by heavy metals is described. Based on the use of ten-meter long optical fibers, the mobile system allows deported measurements. Finally, the laser-assisted drying process studied by the use of a customized laser has not been retained to overcome the problem of moisture.

Airborne Visible Laser Optical Communications Program (AVLOC)

NASA Technical Reports Server (NTRS)

Ward, J. H.

1975-01-01

The design, development, and operation of airborne and ground-based laser communications and laser radar hardware is described in support of the Airborne Visible Laser Optical Communication program. The major emphasis is placed on the development of a highly flexible test bed for the evaluation of laser communications systems techniques and components in an operational environment.

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.

Moving target detection in flash mode against stroboscopic mode by active range-gated laser imaging

NASA Astrophysics Data System (ADS)

Zhang, Xuanyu; Wang, Xinwei; Sun, Liang; Fan, Songtao; Lei, Pingshun; Zhou, Yan; Liu, Yuliang

2018-01-01

Moving target detection is important for the application of target tracking and remote surveillance in active range-gated laser imaging. This technique has two operation modes based on the difference of the number of pulses per frame: stroboscopic mode with the accumulation of multiple laser pulses per frame and flash mode with a single shot of laser pulse per frame. In this paper, we have established a range-gated laser imaging system. In the system, two types of lasers with different frequency were chosen for the two modes. Electric fan and horizontal sliding track were selected as the moving targets to compare the moving blurring between two modes. Consequently, the system working in flash mode shows more excellent performance in motion blurring against stroboscopic mode. Furthermore, based on experiments and theoretical analysis, we presented the higher signal-to-noise ratio of image acquired by stroboscopic mode than flash mode in indoor and underwater environment.

History of Laser Weapon Research

DTIC Science & Technology

2012-01-01

designed to damage, disable, or destroy targets with little or no collateral damage. Airborne Laser (ABL) (CO2) Chemical Oxygen The ABL C-130H aircraft ...mirrors. Weapons systems based on lasers and “ray guns,” long a staple of science fiction, have captured the imagination of people everywhere. But...waves (millimeters to centimeters), with wavelengths 10,000 times longer than lasers. Diffraction of any electromagnetic radia- tion beam is based

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.

Performance of laser guide star adaptive optics at Lick Observatory

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

Olivier, S.S.; An, J.; Avicola, K.

1995-07-19

A sodium-layer laser guide star adaptive optics system has been developed at Lawrence Livermore National Laboratory (LLNL) for use on the 3-meter Shane telescope at Lick Observatory. The system is based on a 127-actuator continuous-surface deformable mirror, a Hartmann wavefront sensor equipped with a fast-framing low-noise CCD camera, and a pulsed solid-state-pumped dye laser tuned to the atomic sodium resonance line at 589 nm. The adaptive optics system has been tested on the Shane telescope using natural reference stars yielding up to a factor of 12 increase in image peak intensity and a factor of 6.5 reduction in image fullmore » width at half maximum (FWHM). The results are consistent with theoretical expectations. The laser guide star system has been installed and operated on the Shane telescope yielding a beam with 22 W average power at 589 nm. Based on experimental data, this laser should generate an 8th magnitude guide star at this site, and the integrated laser guide star adaptive optics system should produce images with Strehl ratios of 0.4 at 2.2 {mu}m in median seeing and 0.7 at 2.2 {mu}m in good seeing.« less

Design of noise barrier inspection system for high-speed railway

NASA Astrophysics Data System (ADS)

Liu, Bingqian; Shao, Shuangyun; Feng, Qibo; Ma, Le; Cholryong, Kim

2016-10-01

The damage of noise barriers will highly reduce the transportation safety of the high-speed railway. In this paper, an online inspection system of noise barrier based on laser vision for the safety of high-speed railway is proposed. The inspection system, mainly consisted of a fast camera and a line laser, installed in the first carriage of the high-speed CIT(Composited Inspection Train).A Laser line was projected on the surface of the noise barriers and the images of the light line were received by the camera while the train is running at high speed. The distance between the inspection system and the noise barrier can be obtained based on laser triangulation principle. The results of field tests show that the proposed system can meet the need of high speed and high accuracy to get the contour distortion of the noise barriers.

Dust-concentration measurement based on Mie scattering of a laser beam

PubMed Central

Yu, Xiaoyu; Shi, Yunbo; Wang, Tian; Sun, Xu

2017-01-01

To realize automatic measurement of the concentration of dust particles in the air, a theory for dust concentration measurement was developed, and a system was designed to implement the dust concentration measurement method based on laser scattering. In the study, the principle of dust concentration detection using laser scattering is studied, and the detection basis of Mie scattering theory is determined. Through simulation, the influence of the incident laser wavelength, dust particle diameter, and refractive index of dust particles on the scattered light intensity distribution are obtained for determining the scattered light intensity curves of single suspended dust particles under different characteristic parameters. A genetic algorithm was used to study the inverse particle size distribution, and the reliability of the measurement system design is proven theoretically. The dust concentration detection system, which includes a laser system, computer circuitry, air flow system, and control system, was then implemented according to the parameters obtained from the theoretical analysis. The performance of the designed system was evaluated. Experimental results show that the system performance was stable and reliable, resulting in high-precision automatic dust concentration measurement with strong anti-interference ability. PMID:28767662

The selective and efficient laser ion source and trap project LIST for on-line production of exotic nuclides

NASA Astrophysics Data System (ADS)

Wendt, Klaus; Gottwald, Tina; Hanstorp, Dag; Mattolat, Christoph; Raeder, Sebastian; Rothe, Sebastian; Schwellnus, Fabio; Havener, Charles; Lassen, Jens; Liu, Yuan

2010-02-01

Laser ion sources based on resonant excitation and ionization of atoms are well-established tools for selective and efficient production of radioactive ion beams. A recent trend is the complementary installation of reliable state-of-the-art all solid-state Ti:Sapphire laser systems. To date, 35 elements of the Periodic Table are available at laser ion sources by using these novel laser systems, which complements the overall accessibility to 54 elements including use of traditional dye lasers. Recent progress in the field concerns the identification of suitable optical excitation schemes for Ti:Sapphire laser excitation as well as technical developments of the source in respect to geometry, cavity material as well as by incorporation of an ion guide system in the form of the laser ion source trap LIST.

Space-based laser-driven MHD generator: Feasibility study

NASA Technical Reports Server (NTRS)

Choi, S. H.

1986-01-01

The feasibility of a laser-driven MHD generator, as a candidate receiver for a space-based laser power transmission system, was investigated. On the basis of reasonable parameters obtained in the literature, a model of the laser-driven MHD generator was developed with the assumptions of a steady, turbulent, two-dimensional flow. These assumptions were based on the continuous and steady generation of plasmas by the exposure of the continuous wave laser beam thus inducing a steady back pressure that enables the medium to flow steadily. The model considered here took the turbulent nature of plasmas into account in the two-dimensional geometry of the generator. For these conditions with the plasma parameters defining the thermal conductivity, viscosity, electrical conductivity for the plasma flow, a generator efficiency of 53.3% was calculated. If turbulent effects and nonequilibrium ionization are taken into account, the efficiency is 43.2%. The study shows that the laser-driven MHD system has potential as a laser power receiver for space applications because of its high energy conversion efficiency, high energy density and relatively simple mechanism as compared to other energy conversion cycles.

An underwater ranging system based on photoacoustic effect occurring on target surface

NASA Astrophysics Data System (ADS)

Ni, Kai; Hu, Kai; Li, Xinghui; Wang, Lidai; Zhou, Qian; Wang, Xiaohao

2016-11-01

In this paper, an underwater ranging system based on photoacoustic effect occurring on target surface is proposed. In this proposal, laser pulse generated by blue-green laser is directly incident on target surface, where the photoacoustic effect occurs and a sound source is formed. And then the sound wave which is also called photoacoustic signal is received by the ultrasonic receiver after passing through water. According to the time delay between transmitting laser and receiving photoacoustic signal, and sound velocity in water, the distance between the target and the ultrasonic receiver can be calculated. Differing from underwater range finding by only laser, this approach can avoid backscattering of laser beam, so easier to implement. Experimental system according to this principle has been constructed to verify the feasibility of this technology. The experimental results showed that a ranging accuracy of 1 mm can be effectively achieved when the target is close to the ultrasonic receiver.

High-average-power 2-kHz laser for generation of ultrashort x-ray pulses.

PubMed

Jiang, Yan; Lee, Taewoo; Li, Wei; Ketwaroo, Gyanprakash; Rose-Petruck, Christoph G

2002-06-01

We describe a Ti:sapphire-based laser-x-ray system specifically designed for generation of ultrafast x-ray pulses in the tenths-of-nanometers spectral range at a 2-kHz repetition rate. To obtain high-contrast laser pulses we divide the laser system into a section for generation of microjoule, high-contrast pulses with pulse cleaning and a subsequent section for chirped-pulse amplification and pulse compression. This laser section operates in conjunction with an x-ray-generation section based on a moving copper wire in a He atmosphere. The high reliability of the entire system permits maintenance-free production of x-ray pulses over tens of hours. Average x-ray fluxes of 10(13) photons/(s 4pi sr 1 keV) at 3 keV and 10(9) photons/(s 4pi sr) above 5 keV of photon energy are produced.

Experiment study of bio-tissue's temperature irradiated by laser based on optical fiber F-P sensor

NASA Astrophysics Data System (ADS)

Shan, Ning; Liu, Xia

2014-08-01

Laser has several advantages, such as strong anti-interference ability, quick speed, high power, agility and precision. It is widely applied in military and medicine fields. When laser acts on human body, biological tissue of human body will appear the phenomenon of ablation and carbonization and solidification. In order to effectively defend excess damage by laser, the thermal effect research of skin tissue should be carried out. Temperature is a key parameter in the processing between laser and bio-tissue. It is the mostly foundation using analyze size of thermal damage area and forecast thermal damage degree. In this paper, the low fineness optical fiber F-P sensing system for temperature measurement is designed and established. The real-time measurement system of temperature generated by laser irradiating bio-tissue is build based on the sensing system. The temperature distributing generated by laser in the bio-tissue is studied through experiment when the spot diameter of emission laser is difference with the same energy density and the energy density is difference with the same spot diameter of emission laser. The experimental results show that the sensing system can be used to the real-time temperature measurement of bio-tissue efficiency. It has small bulk. Its outer diameter is 250μm. And the hurt for bio-tissue is small. It has high respond speed. The respond time of temperature is less than 1s. These can be satisfied with practice demand. When the energy density of laser is same, the temperature rising in the same location is low along the spot diameter of emission laser increasing. When the spot diameter of emission laser is same, the temperature rising in the same location is increasing along with the energy density of laser increasing.

Soliton microcomb range measurement.

PubMed

Suh, Myoung-Gyun; Vahala, Kerry J

2018-02-23

Laser-based range measurement systems are important in many application areas, including autonomous vehicles, robotics, manufacturing, formation flying of satellites, and basic science. Coherent laser ranging systems using dual-frequency combs provide an unprecedented combination of long range, high precision, and fast update rate. We report dual-comb distance measurement using chip-based soliton microcombs. A single pump laser was used to generate dual-frequency combs within a single microresonator as counterpropagating solitons. We demonstrated time-of-flight measurement with 200-nanometer precision at an averaging time of 500 milliseconds within a range ambiguity of 16 millimeters. Measurements at distances up to 25 meters with much lower precision were also performed. Our chip-based source is an important step toward miniature dual-comb laser ranging systems that are suitable for photonic integration. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Design and characteristic analysis of shaping optics for optical trepanning

NASA Astrophysics Data System (ADS)

Zeng, D.; Latham, W. P.; Kar, A.

2005-08-01

Optical trepanning is a new laser drilling method using an annular beam. The annular beams allow numerous irradiance profiles to supply laser energy to the workpiece and thus provide more flexibility in affecting the hole quality than a traditional circular laser beam. The refractive axicon system has been designed to generating a collimated annular beam. In this article, calculations of intensity distributions produced by this refractive system are made by evaluating the Kirchhoff-Fresnel diffraction. It is shown that the refractive system is able to transform a Gaussian beam into a full Gaussian annular beam. The base angle of the axicon lens, input laser beam diameter and intensity profiles are found to be important factors for the axcion refractive system. Their effects on the annular beam profiles are analyzed based on the numerical solutions of the diffraction patterns.

Temperature issues with white laser diodes, calculation and approach for new packages

NASA Astrophysics Data System (ADS)

Lachmayer, Roland; Kloppenburg, Gerolf; Stephan, Serge

2015-01-01

Bright white light sources are of significant importance for automotive front lighting systems. Today's upper class systems mainly use HID or LED light sources. As a further step laser diode based systems offer a high luminance, efficiency and allow the realization of new dynamic and adaptive light functions and styling concepts. The use of white laser diode systems in automotive applications is still limited to laboratories and prototypes even though announcements of laser based front lighting systems have been made. But the environment conditions for vehicles and other industry sectors differ from laboratory conditions. Therefor a model of the system's thermal behavior is set up. The power loss of a laser diode is transported as thermal flux from the junction layer to the diode's case and on to the environment. Therefor its optical power is limited by the maximum junction temperature (for blue diodes typically 125 - 150 °C), the environment temperature and the diode's packaging with its thermal resistances. In a car's headlamp the environment temperature can reach up to 80 °C. While the difference between allowed case temperature and environment temperature is getting small or negative the relevant heat flux also becomes small or negative. In early stages of LED development similar challenges had to be solved. Adapting LED packages to the conditions in a vehicle environment lead to today's efficient and bright headlights. In this paper the need to transfer these results to laser diodes is shown by calculating the diodes lifetimes based on the presented model.

Development of highly compact and low power consumption athermal military laser designators

NASA Astrophysics Data System (ADS)

Sijan, A.

2012-10-01

The utility of military lasers, particularly in the area of laser designation for laser-guided weapons, is well understood. Laser systems based on Nd:YAG have been fielded since the 1980's and over the last three decades have introduced incremental technology steps to improve performance and weight. The most recent technology step has been the introduction of athermal lasers based on laser-diode pumping of Nd:YAG and products are now emerging for use on the battlefield. The technical performance, efficiency, size, weight and power for these lasers, has been key to driving the new production designs. In this paper, we review the development of the laser designs and their introduction since the advent of laser designation. In particular, we compare the relative performance and characteristics over the evolution of fielded laser designators. Moreover, we will review the key building blocks for the design of athermal lasers and describe some critical design issues for engineering and productionisation of a military laser system, including removal of thermal lensing, novel diode-pumping schemes and robustness over the environment. These will be exemplified using results from the development of the SELEX Galileo Type 163 Laser Target Designators. These will cover not only technical performance, power and efficiency, but also thermal management, mass, volume, cost and overall complexity for manufacture.

Series production of next-generation guide-star lasers at TOPTICA and MPBC

NASA Astrophysics Data System (ADS)

Enderlein, Martin; Friedenauer, Axel; Schwerdt, Robin; Rehme, Paul; Wei, Daoping; Karpov, Vladimir; Ernstberger, Bernhard; Leisching, Patrick; Clements, Wallace R. L.; Kaenders, Wilhelm G.

2014-07-01

Large telescopes equipped with adaptive optics require high power 589-nm continuous-wave sources with emission linewidths of ~5 MHz. These guide-star lasers should be highly reliable and simple to operate and maintain for many years at the top of a mountain facility. After delivery of the first 20-W systems to our lead customer ESO, TOPTICA and MPBC have begun series production of next-generation sodium guide-star lasers. The chosen approach is based on ESO's patented narrow-band Raman fiber amplifier (RFA) technology [1]. A master oscillator signal from a TOPTICA 50-mW, 1178-nm diode laser, with stabilized emission frequency and linewidth of ~ 1 MHz, is amplified in an MPBC polarization-maintaining (PM) RFA pumped by a high-power 1120-nm PM fiber laser. With efficient stimulated Brillouin scattering suppression, an unprecedented 40 W of narrow-band RFA output has been obtained. This is spatially mode-matched into a patented resonant-cavity frequency doubler providing also the repumper light [2]. With a diffraction-limited output beam and doubling efficiencies < 80%, all ESO design goals have been easily fulfilled. Together with a wall-plug efficiency of < 3%, including all system controls, and a cooling liquid flow of only 5 l/min, the modular, turn-key, maintenance-free and compact system design allows a direct integration with a launch telescope. With these fiber-based guide star lasers, TOPTICA for the first time offers a fully engineered, off-the-shelf guide star laser system for ground-based optical telescopes. Here we present a comparison of test results of the first batch of laser systems, demonstrating the reproducibility of excellent optical characteristics.

Laser Self-Mixing Fiber Bragg Grating Sensor for Acoustic Emission Measurement.

PubMed

Liu, Bin; Ruan, Yuxi; Yu, Yanguang; Xi, Jiangtao; Guo, Qinghua; Tong, Jun; Rajan, Ginu

2018-06-16

Fiber Bragg grating (FBG) is considered a good candidate for acoustic emission (AE) measurement. The sensing and measurement in traditional FBG-based AE systems are based on the variation in laser intensity induced by the Bragg wavelength shift. This paper presents a sensing system by combining self-mixing interference (SMI) in a laser diode and FBG for AE measurement, aiming to form a new compact and cost-effective sensing system. The measurement model of the overall system was derived. The performance of the presented system was investigated from both aspects of theory and experiment. The results show that the proposed system is able to measure AE events with high resolution and over a wide dynamic frequency range.

Development of Laser Based Remote Sensing System for Inner-Concrete Defects

NASA Astrophysics Data System (ADS)

Shimada, Yoshinori; Kotyaev, Oleg

Laser-based remote sensing using a vibration detection system has been developed using a photorefractive crystal to reduce the effect of concrete surface-roughness. An electric field was applied to the crystal and the reference beam was phase shifted to increase the detection efficiency (DE). The DE increased by factor of 8.5 times compared to that when no voltage and no phase shifting were applied. Vibration from concrete defects can be detected at a distance of 5 m from the system. A vibration-canceling system has also developed that appears to be promising for canceling vibrations between the laser system and the concrete. Finally, we have constructed a prototype system that can be transported in a small truck.

Feedback stabilization system for pulsed single longitudinal mode tunable lasers

DOEpatents

Esherick, Peter; Raymond, Thomas D.

1991-10-01

A feedback stabilization system for pulse single longitudinal mode tunable lasers having an excited laser medium contained within an adjustable length cavity and producing a laser beam through the use of an internal dispersive element, including detection of angular deviation in the output laser beam resulting from detuning between the cavity mode frequency and the passband of the internal dispersive element, and generating an error signal based thereon. The error signal can be integrated and amplified and then applied as a correcting signal to a piezoelectric transducer mounted on a mirror of the laser cavity for controlling the cavity length.

End-pumped 300 W continuous-wave ytterbium-doped all-fiber laser with master oscillator multi-stage power amplifiers configuration.

PubMed

Yin, Shupeng; Yan, Ping; Gong, Mali

2008-10-27

An end-pumped ytterbium-doped all-fiber laser with 300 W output in continuous regime was reported, which was based on master oscillator multi-stage power amplifiers configuration. Monolithic fiber laser system consisted of an oscillator stage and two amplifier stages. Total optical-optical efficiency of monolithic fiber laser was approximately 65%, corresponding to 462 W of pump power coupled into laser system. We proposed a new method to connect power amplifier stage, which was crucial for the application of end-pumped combiner in high power MOPAs all-fiber laser.

OEM fiber laser rangefinder for long-distance measurement

NASA Astrophysics Data System (ADS)

Corman, Alexandre; Chiquet, Frédéric; Avisse, Thomas; Le Flohic, Marc

2015-05-01

SensUp designs and manufactures electro-optical systems based on laser technology, in particular from fiber lasers. Indeed, that kind of source enables us to get a significant peak power with huge repetition rates at the same time, thus combining some characteristics of the two main technologies on the telemetry field today: laser diodes and solid-state lasers. The OEM (Original Equipment Manufacturer) fiber Laser RangeFinder (LRF) set out below, aims to fit the SWaP (Size Weight and Power) requirements of military markets, and might turn out to be a real alternative to other technologies usually used in range finding systems.

Department of Defense high power laser program guidance

NASA Astrophysics Data System (ADS)

Muller, Clifford H.

1994-06-01

The DoD investment of nominally $200 million per year is focused on four high power laser (HPL) concepts: Space-Based Laser (SBL), a Ballistic Missile Defense Organization effort that addresses boost-phase intercept for Theater Missile Defense and National Missile Defense; Airborne Laser (ABL), an Air Force effort that addresses boost-phase intercept for Theater Missile Defense; Ground-Based Laser (GBL), an Air Force effort addressing space control; and Anti-Ship Missile Defense (ASMD), a Navy effort addressing ship-based defense. Each organization is also supporting technology development with the goal of achieving less expensive, brighter, and lighter high power laser systems. These activities represent the building blocks of the DoD program to exploit the compelling characteristics of the high power laser. Even though DoD's HPL program are focused and moderately strong, additional emphasis in a few technical areas could help reduce risk in these programs. In addition, a number of options are available for continuing to use the High-Energy Laser System Test Facility (HELSTF) at White Sands Missile Range. This report provides a brief overview and guidance for the five efforts which comprise the DoD HPL program (SBL, ABL, GBL, ASMD, HELSTF).

Optimisation of cavity parameters for lasers based on AlGaInAsP/InP solid solutions (λ = 1470 nm)

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

Veselov, D A; Ayusheva, K R; Shashkin, I S

2015-10-31

We have studied the effect of laser cavity parameters on the light–current characteristics of lasers based on the AlGaInAs/GaInAsP/InP solid solution system that emit in the spectral range 1400 – 1600 nm. It has been shown that optimisation of cavity parameters (chip length and front facet reflectivity) allows one to improve heat removal from the laser, without changing other laser characteristics. An increase in the maximum output optical power of the laser by 0.5 W has been demonstrated due to cavity design optimisation. (lasers)

Experimental and rendering-based investigation of laser radar cross sections of small unmanned aerial vehicles

NASA Astrophysics Data System (ADS)

Laurenzis, Martin; Bacher, Emmanuel; Christnacher, Frank

2017-12-01

Laser imaging systems are prominent candidates for detection and tracking of small unmanned aerial vehicles (UAVs) in current and future security scenarios. Laser reflection characteristics for laser imaging (e.g., laser gated viewing) of small UAVs are investigated to determine their laser radar cross section (LRCS) by analyzing the intensity distribution of laser reflection in high resolution images. For the first time, LRCSs are determined in a combined experimental and computational approaches by high resolution laser gated viewing and three-dimensional rendering. An optimized simple surface model is calculated taking into account diffuse and specular reflectance properties based on the Oren-Nayar and the Cook-Torrance reflectance models, respectively.

Optics design of laser spotter camera for ex-CCD sensor

NASA Astrophysics Data System (ADS)

Nautiyal, R. P.; Mishra, V. K.; Sharma, P. K.

2015-06-01

Development of Laser based instruments like laser range finder and laser ranger designator has received prominence in modern day military application. Aiming the laser on the target is done with the help of a bore sighted graticule as human eye cannot see the laser beam directly. To view Laser spot there are two types of detectors available, InGaAs detector and Ex-CCD detector, the latter being a cost effective solution. In this paper optics design for Ex-CCD based camera is discussed. The designed system is light weight and compact and has the ability to see the 1064nm pulsed laser spot upto a range of 5 km.

Laser Light: Using Laser Refractometry to Determine Concentration.

ERIC Educational Resources Information Center

Gauger, Robert

1995-01-01

Laser refractometry is a science-technology-based activity that requires students to manipulate a variety of equipment, tools, materials, and critical-thinking skills. Students use a laser to measure the percent of glucose in a solution by calibrating the system, taking measurements, and computing the concentration. (MKR)

Noncoherent Detection of Coherent Optical Heterodyne Signals Corrupted by Laser Phase Noise

DTIC Science & Technology

1991-03-01

replicated speech at the receiving end through the photoelectric effect . Bell’s photophone was the first practical use of light as a transmission...source dominates system performance. An analyti- cal expression representing the effect of laser phase noise on system performance is derived based on a...decision threshold analysis illustrates which noise source dominates system performance. An analytical expression representing the effect of laser phase

Atmospheric effects on laser eye safety and damage to instrumentation

NASA Astrophysics Data System (ADS)

Zilberman, Arkadi; Kopeika, Natan S.

2017-10-01

Electro-optical sensors as well as unprotected human eyes are extremely sensitive to laser radiation and can be permanently damaged from direct or reflected beams. Laser detector/eye hazard depends on the interaction between the laser beam and the media in which it traverses. The environmental conditions including terrain features, atmospheric particulate and water content, and turbulence, may alter the laser's effect on the detector/eye. It is possible to estimate the performance of an electro-optical system as long as the atmospheric propagation of the laser beam can be adequately modeled. More recent experiments and modeling of atmospheric optics phenomena such as inner scale effect, aperture averaging, atmospheric attenuation in NIR-SWIR, and Cn2 modeling justify an update of previous eye/detector safety modeling. In the present work, the influence of the atmospheric channel on laser safety for personnel and instrumentation is shown on the basis of theoretical and experimental data of laser irradiance statistics for different atmospheric conditions. A method for evaluating the probability of damage and hazard distances associated with the use of laser systems in a turbulent atmosphere operating in the visible and NIR-SWIR portions of the electromagnetic spectrum is presented. It can be used as a performance prediction model for directed energy engagement of ground-based or air-based systems.

Analysis of laser jamming to satellite-based detector

NASA Astrophysics Data System (ADS)

Wang, Si-wen; Guo, Li-hong; Guo, Ru-hai

2009-07-01

The reconnaissance satellite, communication satellite and navigation satellite used in the military applications have played more and more important role in the advanced technique wars and already become the significant support and aid system for military actions. With the development of all kinds of satellites, anti-satellite laser weapons emerge as the times require. The experiments and analyses of laser disturbing CCD (charge coupled detector) in near ground have been studied by many research groups, but their results are not suitable to the case that using laser disturbs the satellite-based detector. Because the distance between the satellite-based detector and the ground is very large, it is difficult to damage it directly. However the optical receive system of satellite detector has large optical gain, so laser disturbing satellite detector is possible. In order to determine its feasibility, the theoretical analyses and experimental study are carried out in the paper. Firstly, the influence factors of laser disturbing satellite detector are analyzed in detail, which including laser power density on the surface of the detector after long distance transmission, and laser power density threshold for disturbing etc. These factors are not only induced by the satellite orbit, but dependence on the following parameters: laser average power in the ground, laser beam quality, tracing and aiming precision and atmospheric transmission. A calculation model is developed by considering all factors which then the power density entering into the detector can be calculated. Secondly, the laser disturbing experiment is performed by using LD (laser diode) with the wavelength 808 nm disturbing CCD 5 kilometer away, which the disturbing threshold value is obtained as 3.55×10-4mW/cm2 that coincides with other researcher's results. Finally, using the theoretical model, the energy density of laser on the photosensitive surface of MSTI-3 satellite detector is estimated as about 100mW/cm2, which is largely exceed the disturbing threshold and therefore verify the feasibility of using this kind of laser disturbing the satellite-based detector. According to the results. using the similar laser power density absolutely saturate the requirements to laser disturbing satellite-based detector. If considering the peak power of pulsed laser, even decrease laser average power, it is also possible to damage the detector. This result will provide the reliable evidences to evaluate the effect of laser disturbing satellite-based detector.

Concept for a Micro Autonomous Ultrasonic Instrument (MAUI)

NASA Technical Reports Server (NTRS)

Wilson, William C.; Atkinson, Gary M.

2002-01-01

We investigate a concept for the construction a mobile Micro Optical ElectroMechanical Systems (MOEMS) based laser ultrasonic instrument to serve as a Micro Autonomous Ultrasonic Instrument (MAUI). The system will consist of a laser ultrasonic instrument fabricated using Micro Electro-Mechanical Systems (MEMS) technology, and a MEMS based walking platform like those developed by Pister et al. at Berkeley. This small system will allow for automated remote Non-Destructive Evaluation (NDE) of aerospace vehicles.

Hollow Core Optical Fiber Gas Lasers: Toward Novel and Practical Systems in Fused Silica

DTIC Science & Technology

2017-05-18

Hollow core Optically pumped Fiber Gas LASer’s (HOFGLAS’s) based on population inversion combine advantages of fiber lasers such as long interaction...polarization dependent fiber properties. Preliminary experiments were performed toward simultaneous lasing in the visible and near infrared; lasing in...words) Hollow core Optically pumped Fiber Gas LASer’s (HOFGLAS’s) based on population inversion combine advantages of fiber lasers such as long

Modeling of ground based laser propagation to low Earth orbit object for maneuver

NASA Astrophysics Data System (ADS)

Smith, Liam C.; Allen, Jeffrey H.; Bold, Matthew M.

2017-08-01

The Space Environment Research Centre (SERC) endeavors to demonstrate the ability to maneuver high area to mass ratio objects using ground based lasers. Lockheed Martin has been leading system performance modeling for this project that includes high power laser propagation through the atmosphere, target interactions and subsequent orbital maneuver of the object. This paper will describe the models used, model assumptions and performance estimates for laser maneuver demonstration.

Real-Time N2O Gas Detection System for Agricultural Production Using a 4.6-μm-Band Laser Source Based on a Periodically Poled LiNbO3 Ridge Waveguide

PubMed Central

Tokura, Akio; Asobe, Masaki; Enbutsu, Koji; Yoshihara, Toshihiro; Hashida, Shin-nosuke; Takenouchi, Hirokazu

2013-01-01

This article describes a gas monitoring system for detecting nitrous oxide (N2O) gas using a compact mid-infrared laser source based on difference-frequency generation in a quasi-phase-matched LiNbO3 waveguide. We obtained a stable output power of 0.62 mW from a 4.6-μm-band continuous-wave laser source operating at room temperature. This laser source enabled us to detect atmospheric N2O gas at a concentration as low as 35 parts per billion. Using this laser source, we constructed a new real-time in-situ monitoring system for detecting N2O gas emitted from potted plants. A few weeks of monitoring with the developed detection system revealed a strong relationship between nitrogen fertilization and N2O emission. This system is promising for the in-situ long-term monitoring of N2O in agricultural production, and it is also applicable to the detection of other greenhouse gases. PMID:23921829

Real-time N2O gas detection system for agricultural production using a 4.6-µm-band laser source based on a periodically poled LiNbO3 ridge waveguide.

PubMed

Tokura, Akio; Asobe, Masaki; Enbutsu, Koji; Yoshihara, Toshihiro; Hashida, Shin-nosuke; Takenouchi, Hirokazu

2013-08-05

This article describes a gas monitoring system for detecting nitrous oxide (N2O) gas using a compact mid-infrared laser source based on difference-frequency generation in a quasi-phase-matched LiNbO3 waveguide. We obtained a stable output power of 0.62 mW from a 4.6-μm-band continuous-wave laser source operating at room temperature. This laser source enabled us to detect atmospheric N2O gas at a concentration as low as 35 parts per billion. Using this laser source, we constructed a new real-time in-situ monitoring system for detecting N2O gas emitted from potted plants. A few weeks of monitoring with the developed detection system revealed a strong relationship between nitrogen fertilization and N2O emission. This system is promising for the in-situ long-term monitoring of N2O in agricultural production, and it is also applicable to the detection of other greenhouse gases.

Analysis of laser energy characteristics of laser guided weapons based on the hardware-in-the-loop simulation system

NASA Astrophysics Data System (ADS)

Zhu, Yawen; Cui, Xiaohong; Wang, Qianqian; Tong, Qiujie; Cui, Xutai; Li, Chenyu; Zhang, Le; Peng, Zhong

2016-11-01

The hardware-in-the-loop simulation system, which provides a precise, controllable and repeatable test conditions, is an important part of the development of the semi-active laser (SAL) guided weapons. In this paper, laser energy chain characteristics were studied, which provides a theoretical foundation for the SAL guidance technology and the hardware-in-the-loop simulation system. Firstly, a simplified equation was proposed to adjust the radar equation according to the principles of the hardware-in-the-loop simulation system. Secondly, a theoretical model and calculation method were given about the energy chain characteristics based on the hardware-in-the-loop simulation system. We then studied the reflection characteristics of target and the distance between the missile and target with major factors such as the weather factors. Finally, the accuracy of modeling was verified by experiment as the values measured experimentally generally follow the theoretical results from the model. And experimental results revealed that ratio of attenuation of the laser energy exhibited a non-linear change vs. pulse number, which were in accord with the actual condition.

A digital frequency stabilization system of external cavity diode laser based on LabVIEW FPGA

NASA Astrophysics Data System (ADS)

Liu, Zhuohuan; Hu, Zhaohui; Qi, Lu; Wang, Tao

2015-10-01

Frequency stabilization for external cavity diode laser has played an important role in physics research. Many laser frequency locking solutions have been proposed by researchers. Traditionally, the locking process was accomplished by analog system, which has fast feedback control response speed. However, analog system is susceptible to the effects of environment. In order to improve the automation level and reliability of the frequency stabilization system, we take a grating-feedback external cavity diode laser as the laser source and set up a digital frequency stabilization system based on National Instrument's FPGA (NI FPGA). The system consists of a saturated absorption frequency stabilization of beam path, a differential photoelectric detector, a NI FPGA board and a host computer. Many functions, such as piezoelectric transducer (PZT) sweeping, atomic saturation absorption signal acquisition, signal peak identification, error signal obtaining and laser PZT voltage feedback controlling, are totally completed by LabVIEW FPGA program. Compared with the analog system, the system built by the logic gate circuits, performs stable and reliable. User interface programmed by LabVIEW is friendly. Besides, benefited from the characteristics of reconfiguration, the LabVIEW program is good at transplanting in other NI FPGA boards. Most of all, the system periodically checks the error signal. Once the abnormal error signal is detected, FPGA will restart frequency stabilization process without manual control. Through detecting the fluctuation of error signal of the atomic saturation absorption spectrum line in the frequency locking state, we can infer that the laser frequency stability can reach 1MHz.

Femtosecond laser-induced periodic surface structure on the Ti-based nanolayered thin films

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

Petrović, Suzana M.; Gaković, B.; Peruško, D.

2013-12-21

Laser-induced periodic surface structures (LIPSSs) and chemical composition changes of Ti-based nanolayered thin films (Al/Ti, Ni/Ti) after femtosecond (fs) laser pulses action were studied. Irradiation is performed using linearly polarized Ti:Sapphire fs laser pulses of 40 fs pulse duration and 800 nm wavelength. The low spatial frequency LIPSS (LSFL), oriented perpendicular to the laser polarization with periods slightly lower than the irradiation wavelength, was typically formed at elevated laser fluences. On the contrary, high spatial frequency LIPSS (HSFL) with uniform period of 155 nm, parallel to the laser light polarization, appeared at low laser fluences, as well as in themore » wings of the Gaussian laser beam distribution for higher used fluence. LSFL formation was associated with the material ablation process and accompanied by the intense formation of nanoparticles, especially in the Ni/Ti system. The composition changes at the surface of both multilayer systems in the LSFL area indicated the intermixing between layers and the substrate. Concentration and distribution of all constitutive elements in the irradiated area with formed HSFLs were almost unchanged.« less

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.

Latest developments for low-power infrared laser-based trace gas sensors for sensor networks

NASA Astrophysics Data System (ADS)

So, Stephen; Thomazy, David; Wang, Wen; Marchat, Oscar; Wysocki, Gerard

2011-09-01

Academic and industrial researchers require ultra-low power, compact laser based trace-gas sensor systems for the most demanding environmental and space-borne applications. Here the latest results from research projects addressing these applications will be discussed: 1) an ultra-compact CO2 sensor based on a continuous wave quantum cascade laser, 2) an ultra-sensitive Faraday rotation spectrometer for O2 detection, 3) a fully ruggedized compact and low-power laser spectrometer, and 4) a novel non-paraxial nonthin multipass cell. Preliminary tests and projection for performance of future sensors based on this technology is presented.

FPGA based demodulation of laser induced fluorescence in plasmas

NASA Astrophysics Data System (ADS)

Mattingly, Sean W.; Skiff, Fred

2018-04-01

We present a field programmable gate array (FPGA)-based system that counts photons from laser-induced fluorescence (LIF) on a laboratory plasma. This is accomplished with FPGA-based up/down counters that demodulate the data, giving a background-subtracted LIF signal stream that is updated with a new point as each laser amplitude modulation cycle completes. We demonstrate using the FPGA to modulate a laser at 1 MHz and demodulate the resulting LIF data stream. This data stream is used to calculate an LIF-based measurement sampled at 1 MHz of a plasma ion fluctuation spectrum.

Potential of laser for SPS power transmission

NASA Technical Reports Server (NTRS)

Bain, C. N.

1978-01-01

Research on the feasibility of using a laser subsystem as an additional option for the transmission of the satellite power system (STS) power is presented. Current laser work and predictions for future laser performance provide a level of confidence that the development of a laser power transmission system is technologically feasible in the time frame required to develop the SBS. There are significant economic advantages in lower ground distribution costs and a reduction of more than two orders of magnitude in real estate requirements for ground based receiving/conversion sites.

Tunable diode laser absorption spectroscopy-based tomography system for on-line monitoring of two-dimensional distributions of temperature and H2O mole fraction.

PubMed

Xu, Lijun; Liu, Chang; Jing, Wenyang; Cao, Zhang; Xue, Xin; Lin, Yuzhen

2016-01-01

To monitor two-dimensional (2D) distributions of temperature and H2O mole fraction, an on-line tomography system based on tunable diode laser absorption spectroscopy (TDLAS) was developed. To the best of the authors' knowledge, this is the first report on a multi-view TDLAS-based system for simultaneous tomographic visualization of temperature and H2O mole fraction in real time. The system consists of two distributed feedback (DFB) laser diodes, a tomographic sensor, electronic circuits, and a computer. The central frequencies of the two DFB laser diodes are at 7444.36 cm(-1) (1343.3 nm) and 7185.6 cm(-1) (1391.67 nm), respectively. The tomographic sensor is used to generate fan-beam illumination from five views and to produce 60 ray measurements. The electronic circuits not only provide stable temperature and precise current controlling signals for the laser diodes but also can accurately sample the transmitted laser intensities and extract integrated absorbances in real time. Finally, the integrated absorbances are transferred to the computer, in which the 2D distributions of temperature and H2O mole fraction are reconstructed by using a modified Landweber algorithm. In the experiments, the TDLAS-based tomography system was validated by using asymmetric premixed flames with fixed and time-varying equivalent ratios, respectively. The results demonstrate that the system is able to reconstruct the profiles of the 2D distributions of temperature and H2O mole fraction of the flame and effectively capture the dynamics of the combustion process, which exhibits good potential for flame monitoring and on-line combustion diagnosis.

Tunable diode laser absorption spectroscopy-based tomography system for on-line monitoring of two-dimensional distributions of temperature and H2O mole fraction

NASA Astrophysics Data System (ADS)

Xu, Lijun; Liu, Chang; Jing, Wenyang; Cao, Zhang; Xue, Xin; Lin, Yuzhen

2016-01-01

To monitor two-dimensional (2D) distributions of temperature and H2O mole fraction, an on-line tomography system based on tunable diode laser absorption spectroscopy (TDLAS) was developed. To the best of the authors' knowledge, this is the first report on a multi-view TDLAS-based system for simultaneous tomographic visualization of temperature and H2O mole fraction in real time. The system consists of two distributed feedback (DFB) laser diodes, a tomographic sensor, electronic circuits, and a computer. The central frequencies of the two DFB laser diodes are at 7444.36 cm-1 (1343.3 nm) and 7185.6 cm-1 (1391.67 nm), respectively. The tomographic sensor is used to generate fan-beam illumination from five views and to produce 60 ray measurements. The electronic circuits not only provide stable temperature and precise current controlling signals for the laser diodes but also can accurately sample the transmitted laser intensities and extract integrated absorbances in real time. Finally, the integrated absorbances are transferred to the computer, in which the 2D distributions of temperature and H2O mole fraction are reconstructed by using a modified Landweber algorithm. In the experiments, the TDLAS-based tomography system was validated by using asymmetric premixed flames with fixed and time-varying equivalent ratios, respectively. The results demonstrate that the system is able to reconstruct the profiles of the 2D distributions of temperature and H2O mole fraction of the flame and effectively capture the dynamics of the combustion process, which exhibits good potential for flame monitoring and on-line combustion diagnosis.

Tunable diode laser absorption spectroscopy-based tomography system for on-line monitoring of two-dimensional distributions of temperature and H{sub 2}O mole fraction

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

Xu, Lijun, E-mail: lijunxu@buaa.edu.cn; Liu, Chang; Jing, Wenyang

2016-01-15

To monitor two-dimensional (2D) distributions of temperature and H{sub 2}O mole fraction, an on-line tomography system based on tunable diode laser absorption spectroscopy (TDLAS) was developed. To the best of the authors’ knowledge, this is the first report on a multi-view TDLAS-based system for simultaneous tomographic visualization of temperature and H{sub 2}O mole fraction in real time. The system consists of two distributed feedback (DFB) laser diodes, a tomographic sensor, electronic circuits, and a computer. The central frequencies of the two DFB laser diodes are at 7444.36 cm{sup −1} (1343.3 nm) and 7185.6 cm{sup −1} (1391.67 nm), respectively. The tomographicmore » sensor is used to generate fan-beam illumination from five views and to produce 60 ray measurements. The electronic circuits not only provide stable temperature and precise current controlling signals for the laser diodes but also can accurately sample the transmitted laser intensities and extract integrated absorbances in real time. Finally, the integrated absorbances are transferred to the computer, in which the 2D distributions of temperature and H{sub 2}O mole fraction are reconstructed by using a modified Landweber algorithm. In the experiments, the TDLAS-based tomography system was validated by using asymmetric premixed flames with fixed and time-varying equivalent ratios, respectively. The results demonstrate that the system is able to reconstruct the profiles of the 2D distributions of temperature and H{sub 2}O mole fraction of the flame and effectively capture the dynamics of the combustion process, which exhibits good potential for flame monitoring and on-line combustion diagnosis.« less

A 100J-level nanosecond pulsed DPSSL for pumping high-efficiency, high-repetition rate PW-class lasers

NASA Astrophysics Data System (ADS)

De Vido, M.; Ertel, K.; Mason, P. D.; Banerjee, S.; Phillips, P. J.; Smith, J. M.; Butcher, T. J.; Chekhlov, O.; Divoky, M.; Pilar, J.; Hooker, C.; Shaikh, W.; Lucianetti, A.; Hernandez-Gomez, C.; Mocek, T.; Edwards, C.; Collier, J. L.

2017-02-01

In this paper, we review the development, at the STFC's Central Laser Facility (CLF), of high energy, high repetition rate diode-pumped solid-state laser (DPSSL) systems based on cryogenically-cooled multi-slab ceramic Yb:YAG. Up to date, two systems have been completed, namely the DiPOLE prototype and the DiPOLE100 system. The DiPOLE prototype has demonstrated amplification of nanosecond pulses in excess of 10 J at 10 Hz repetition rate with an opticalto- optical efficiency of 22%. The larger scale DiPOLE100 system, designed to deliver 100J temporally-shaped nanosecond pulses at 10 Hz repetition rate, has been developed at the CLF for the HiLASE project in the Czech Republic. Recent experiments conducted on the DiPOLE100 system demonstrated the energy scalability of the DiPOLE concept to the 100 J pulse energy level. Furthermore, second harmonic generation experiments carried out on the DiPOLE prototype confirmed the suitability of DiPOLE-based systems for pumping high repetition rate PW-class laser systems based on Ti:sapphire or optical parametric chirped pulse amplification (OPCPA) technology.

Field-programmable gate array-controlled sweep velocity-locked laser pulse generator

NASA Astrophysics Data System (ADS)

Chen, Zhen; Hefferman, Gerald; Wei, Tao

2017-05-01

A field-programmable gate array (FPGA)-controlled sweep velocity-locked laser pulse generator (SV-LLPG) design based on an all-digital phase-locked loop (ADPLL) is proposed. A distributed feedback laser with modulated injection current was used as a swept-frequency laser source. An open-loop predistortion modulation waveform was calibrated using a feedback iteration method to initially improve frequency sweep linearity. An ADPLL control system was then implemented using an FPGA to lock the output of a Mach-Zehnder interferometer that was directly proportional to laser sweep velocity to an on-board system clock. Using this system, linearly chirped laser pulses with a sweep bandwidth of 111.16 GHz were demonstrated. Further testing evaluating the sensing utility of the system was conducted. In this test, the SV-LLPG served as the swept laser source of an optical frequency-domain reflectometry system used to interrogate a subterahertz range fiber structure (sub-THz-FS) array. A static strain test was then conducted and linear sensor results were observed.

Systems efficiency and specific mass estimates for direct and indirect solar-pumped closed-cycle high-energy lasers in space

NASA Technical Reports Server (NTRS)

Monson, D. J.

1978-01-01

Based on expected advances in technology, the maximum system efficiency and minimum specific mass have been calculated for closed-cycle CO and CO2 electric-discharge lasers (EDL's) and a direct solar-pumped laser in space. The efficiency calculations take into account losses from excitation gas heating, ducting frictional and turning losses, and the compressor efficiency. The mass calculations include the power source, radiator, compressor, fluids, ducting, laser channel, optics, and heat exchanger for all of the systems; and in addition the power conditioner for the EDL's and a focusing mirror for the solar-pumped laser. The results show the major component masses in each system, show which is the lightest system, and provide the necessary criteria for solar-pumped lasers to be lighter than the EDL's. Finally, the masses are compared with results from other studies for a closed-cycle CO2 gasdynamic laser (GDL) and the proposed microwave satellite solar power station (SSPS).

Remote sensing of atmospheric pressure and sea state using laser altimeters

NASA Technical Reports Server (NTRS)

Gardner, C. S.

1985-01-01

Short-pulse multicolor laser ranging systems are currently being developed for satellite ranging applications. These systems use Q-switched pulsed lasers and streak-tube cameras to provide timing accuracies approaching a few picoseconds. Satellite laser ranging systems have been used to evaluate many important geophysical phenomena such as fault motion, polar motion and solid earth tides, by measuring the orbital perturbations of retroreflector equipped satellites. Some existing operational systems provide range resolution approaching a few millimeters. There is currently considerable interest in adapting these highly accurate systems for use as airborne and satellite based altimeters. Potential applications include the measurement of sea state, ground topography and atmospheric pressure. This paper reviews recent progress in the development of multicolor laser altimeters for use in monitoring sea state and atmospheric pressure.

Personal medical information system using laser card

NASA Astrophysics Data System (ADS)

Cho, Seong H.; Kim, Keun Ho; Choi, Hyung-Sik; Park, Hyun Wook

1996-04-01

The well-known hospital information system (HIS) and the picture archiving and communication system (PACS) are typical applications of multimedia to medical area. This paper proposes a personal medical information save-and-carry system using a laser card. This laser card is very useful, especially in emergency situations, because the medical information in the laser card can be read at anytime and anywhere if there exists a laser card reader/writer. The contents of the laser card include the clinical histories of a patient such as clinical chart, exam result, diagnostic reports, images, and so on. The purpose of this system is not a primary diagnosis, but emergency reference of clinical history of the patient. This personal medical information system consists of a personal computer integrated with laser card reader/writer, color frame grabber, color CCD camera and a high resolution image scanner optionally. Window-based graphical user interface was designed for easy use. The laser card has relatively sufficient capacity to store the personal medical information, and has fast access speed to restore and load the data with a portable size as compact as a credit card. Database items of laser card provide the doctors with medical data such as laser card information, patient information, clinical information, and diagnostic result information.

Electrically pumped graphene-based Landau-level laser

NASA Astrophysics Data System (ADS)

Brem, Samuel; Wendler, Florian; Winnerl, Stephan; Malic, Ermin

2018-03-01

Graphene exhibits a nonequidistant Landau quantization with tunable Landau-level (LL) transitions in the technologically desired terahertz spectral range. Here, we present a strategy for an electrically driven terahertz laser based on Landau-quantized graphene as the gain medium. Performing microscopic modeling of the coupled electron, phonon, and photon dynamics in such a laser, we reveal that an inter-LL population inversion can be achieved resulting in the emission of coherent terahertz radiation. The presented paper provides a concrete recipe for the experimental realization of tunable graphene-based terahertz laser systems.

Ultrasound Guidance and Monitoring of Laser-Based Fat Removal

PubMed Central

Shah, Jignesh; Thomsen, Sharon; Milner, Thomas E.; Emelianov, Stanislav Y.

2009-01-01

Background and Objectives We report on a study to investigate feasibility of utilizing ultrasound imaging to guide laser removal of subcutaneous fat. Ultrasound imaging can be used to identify the tissue composition and to monitor the temperature increase in response to laser irradiation. Study Design/Materials and Methods Laser heating was performed on ex vivo porcine subcutaneous fat through the overlying skin using a continuous wave laser operating at 1,210 nm optical wavelength. Ultrasound images were recorded using a 10 MHz linear array-based ultrasound imaging system. Results Ultrasound imaging was utilized to differentiate between water-based and lipid-based regions within the porcine tissue and to identify the dermis-fat junction. Temperature maps during the laser exposure in the skin and fatty tissue layers were computed. Conclusions Results of our study demonstrate the potential of using ultrasound imaging to guide laser fat removal. PMID:19065554

Laser engineering of microbial systems

NASA Astrophysics Data System (ADS)

Yusupov, V. I.; Gorlenko, M. V.; Cheptsov, V. S.; Minaev, N. V.; Churbanova, E. S.; Zhigarkov, V. S.; Chutko, E. A.; Evlashin, S. A.; Chichkov, B. N.; Bagratashvili, V. N.

2018-06-01

A technology of laser engineering of microbial systems (LEMS) based on the method of laser-induced transfer of heterogeneous mixtures containing microorganisms (laser bioprinting) is described. This technology involves laser printing of soil microparticles by focusing near-infrared laser pulses on a specially prepared gel/soil mixture spread onto a gold-coated glass plate. The optimal range of laser energies from the point of view of the formation of stable jets and droplets with minimal negative impact on living systems of giant accelerations, laser pulse irradiation, and Au nanoparticles was found. Microsamples of soil were printed on glucose-peptone-yeast agar plates to estimate the LEMS process influence on structural and morphological microbial diversity. The obtained results were compared with traditionally treated soil samples. It was shown that LEMS technology allows significantly increasing the biodiversity of printed organisms and is effective for isolating rare or unculturable microorganisms.

Technology assessment of high pulse energy CO(2) lasers for remote sensing from satellites

NASA Technical Reports Server (NTRS)

Hess, R. V.; Brockman, P.; Schryer, D. R.; Miller, I. M.; Bair, C. H.; Sidney, B. D.; Wood, G. M.; Upchurch, B. T.; Brown, K. G.

1985-01-01

Developments and needs for research to extend the lifetime and optimize the configuration of CO2 laser systems for satellite based on remote sensing of atmospheric wind velocities and trace gases are reviewed. The CO2 laser systems for operational satellite application will require lifetimes which exceed 1 year. Progress in the development of efficient low temperature catalysts and gas mixture modifications for extending the lifetime of high pulse energy closed cycle common and rare isotope CO2 lasers and of sealed CW CO2 lasers is reviewed. Several CO2 laser configurations are under development to meet the requirements including: unstable resonators, master oscillator power amplifiers and telescopic stable resonators, using UV or E-beam preionization. Progress in the systems is reviewed and tradeoffs in the system parameters are discussed.

Mobile Laser Doppler System Checkout and Calibration : Volume 1. Text

DOT National Transportation Integrated Search

1977-06-01

A program has been carried out to make modifications to the Lockheed-Huntsville Mobiel Laser Doppler Velocimeter(LDV)system; to calibrate and operate the system at the John F. Kennedy (JFK) Airport; to obtain a data base of wind, wind shear, and wake...

Mobile Laser Doppler System Checkout and Calibration : Volume 2. Appendixes.

DOT National Transportation Integrated Search

1977-06-01

A program has been carried out to make modifications to the Lockheed-Huntsville Mobiel Laser Doppler Velocimeter(LDV)system; to calibrate and operate the system at the John F. Kennedy (JFK) Airport; to obtain a data base of wind, wind shear, and wake...

Characterization of the surfaces of platinum/tin oxide based catalysts by Fourier transform spectroscopy (FTIR)

NASA Technical Reports Server (NTRS)

Keiser, Joseph T.

1989-01-01

The Laser Atmospheric Wind Sounder (LAWS) Program has as one of its goals the development of a satellite based carbon dioxide laser for making wind velocity measurements. The specifications for this laser include the requirement that the laser operate at a repetition rate of 10 Hertz continuously for three years. Earth-based carbon dioxide lasers can operate for only a short time on a single charge of gas because the lasing action causes the CO2 to break down into CO and O2. Therefore, earth-based CO2 lasers are generally operated in a flow through mode in which the spent gas is continually exhausted and fresh gas is continually added. For a satellite based system, however, a recirculation system is desired because it is not practical to send up extra tanks of CO2. A catalyst which could enable a recirculating CO2 laser to function continuously for three years needs to be developed. In the development of a catalyst system there are many variables. Obviously, not all possible formulations can be tested for three years, therefore, an accurate model which is based on the reaction mechanism is needed. The construction of a multistep reaction mechanism is similar to the construction of a jigsaw puzzle. Different techniques each supply a piece of the puzzle and the researcher must put the pieces together. Transmission infrared spectroscopy was shown to be very useful in supplying some of the information needed to elucidate reaction mechanisms. The purpose was to see what kind of information might be obtained about the NASA catalyst using infrared absorption spectroscopy. Approximately 200 infrared spectra of the prototype Pt/tin oxide catalyst and its precursor components are observed under a variety of different conditions. The most significant observations are summarized.

Liquid level sensor based on fiber ring laser with single-mode-offset coreless-single-mode fiber structure

NASA Astrophysics Data System (ADS)

Wang, Zixiao; Tan, Zhongwei; Xing, Rui; Liang, Linjun; Qi, Yanhui; Jian, Shuisheng

2016-10-01

A novel reflective liquid level sensor based on single-mode-offset coreless-single-mode (SOCS) fiber structure is proposed and experimentally demonstrated. Theory analyses and experimental results indicate that offset fusion can remarkably enhance the sensitivity of sensor. Ending-reflecting structure makes the sensor compact and easy to deploy. Meanwhile, we propose a laser sensing system, and the SOCS structure is used as sensing head and laser filter simultaneously. Experimental results show that laser spectra with high optical signal-to-noise ratio (-30 dB) and narrow 3-dB bandwidth (<0.15 nm) are achieved. Various liquids with different indices are used for liquid level sensing, besides, the refractive index sensitivity is also investigated. In measurement range, the sensing system presents steady laser output.

Development and optimization of a diode laser for photodynamic therapy.

PubMed

Lim, Hyun Soo

2011-01-01

This study demonstrated the development of a laser system for cancer treatment with photodynamic therapy (PDT) based on a 635 nm laser diode. In order to optimize efficacy in PDT, the ideal laser system should deliver a homogeneous nondivergent light energy with a variable spot size and specific wavelength at a stable output power. We developed a digital laser beam controller using the constant current method to protect the laser diode resonator from the current spikes and other fluctuations, and electrical faults. To improve the PDT effects, the laser system should deliver stable laser energy in continuous wave (CW), burst mode and super burst mode, with variable irradiation times depending on the tumor type and condition. The experimental results showed the diode laser system described herein was eminently suitable for PDT. The laser beam was homogeneous without diverging and the output power increased stably and in a linear manner from 10 mW to 1500 mW according to the increasing input current. Variation between the set and delivered output was less than 7%. The diode laser system developed by the author for use in PDT was compact, user-friendly, and delivered a stable and easily adjustable output power at a specific wavelength and user-set emission modes.

Development and optimization of a diode laser for photodynamic therapy

PubMed Central

Lim, Hyun Soo

2011-01-01

Background and Aims: This study demonstrated the development of a laser system for cancer treatment with photodynamic therapy (PDT) based on a 635 nm laser diode. In order to optimize efficacy in PDT, the ideal laser system should deliver a homogeneous nondivergent light energy with a variable spot size and specific wavelength at a stable output power. Materials and Methods: We developed a digital laser beam controller using the constant current method to protect the laser diode resonator from the current spikes and other fluctuations, and electrical faults. To improve the PDT effects, the laser system should deliver stable laser energy in continuous wave (CW), burst mode and super burst mode, with variable irradiation times depending on the tumor type and condition. Results and Comments: The experimental results showed the diode laser system described herein was eminently suitable for PDT. The laser beam was homogeneous without diverging and the output power increased stably and in a linear manner from 10 mW to 1500 mW according to the increasing input current. Variation between the set and delivered output was less than 7%. Conclusions: The diode laser system developed by the author for use in PDT was compact, user-friendly, and delivered a stable and easily adjustable output power at a specific wavelength and user-set emission modes. PMID:24155529

An auto-locked diode laser system for precision metrology

NASA Astrophysics Data System (ADS)

Beica, H. C.; Carew, A.; Vorozcovs, A.; Dowling, P.; Pouliot, A.; Barron, B.; Kumarakrishnan, A.

2017-05-01

We present a unique external cavity diode laser system that can be auto-locked with reference to atomic and molecular spectra. The vacuum-sealed laser head design uses an interchangeable base-plate comprised of a laser diode and optical elements that can be selected for desired wavelength ranges. The feedback light to the laser diode is provided by a narrow-band interference filter, which can be tuned from outside the laser cavity to fineadjust the output wavelength in vacuum. To stabilize the laser frequency, the digital laser controller relies either on a pattern-matching algorithm stored in memory, or on first or third derivative feedback. We have used the laser systems to perform spectroscopic studies in rubidium at 780 nm, and in iodine at 633 nm. The linewidth of the 780-nm laser system was measured to be ˜500 kHz, and we present Allan deviation measurements of the beat note and the lock stability. Furthermore, we show that the laser system can be the basis for a new class of lidar transmitters in which a temperature-stabilized fiber-Bragg grating is used to generate frequency references for on-line points of the transmitter. We show that the fiber-Bragg grating spectra can be calibrated with reference to atomic transitions.

Optical characterization in wide spectral range by a coherent spectrophotometer

NASA Astrophysics Data System (ADS)

Sirutkaitis, Valdas; Eckardt, Robert C.; Balachninaite, Ona; Grigonis, Rimantas; Melninkaitis, A.; Rakickas, T.

2003-11-01

We report on the development and use of coherent spectrophotometers specialized for the unusual requirements of characterizing nonlinear optical materials and multilayer dielectric coatings used in laser systems. A large dynamic range is required to measure the linear properties of transmission, reflection and absorption and nonlinear properties of laser-induced damage threshold and nonlinear frequency conversion. Optical parametric oscillators generate coherent radiation that is widely tunable with instantaneous powers that can range from milliwatts to megawatts and are well matched to this application. As particular example a laser spectrophotometer based on optical parametric oscillators and a diode-pumped, Q-switched Nd:YAG laser and suitable for optical characterization in the spectral range 420-4500 nm is described. Measurements include reflectance and transmittance, absorption, scattering and laser-induced damage thresholds. Possibilities of a system based on a 130-fs Ti:sapphire laser and optical parametric generators are also discussed.

A UWOC system based on a 6 m/5.2 Gbps 680 nm vertical-cavity surface-emitting laser

NASA Astrophysics Data System (ADS)

Li, Chung-Yi; Tsai, Wen-Shing

2018-02-01

This study proves that an underwater wireless optical communication (UWOC) based on a 6 m/5.2 Gbps 68 nm vertical-cavity surface-emitting laser (VCSEL)-based system is superior to a 405 nm UWOC system. This UWOC application is the first to use a VCSEL at approximately 680 nm. The experiment also proved that a 680 nm VCSEL has the same transmission distance as that of an approximately 405 nm laser diode. The 680 nm VCSEL has a 5.2 Gbps high transmission rate and can transmit up to 6 m. Thus, the setup is the best alternative solution for high-speed UWOC applications.

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.

Integrated test system of infrared and laser data based on USB 3.0

NASA Astrophysics Data System (ADS)

Fu, Hui Quan; Tang, Lin Bo; Zhang, Chao; Zhao, Bao Jun; Li, Mao Wen

2017-07-01

Based on USB3.0, this paper presents the design method of an integrated test system for both infrared image data and laser signal data processing module. The core of the design is FPGA logic control, the design uses dual-chip DDR3 SDRAM to achieve high-speed laser data cache, and receive parallel LVDS image data through serial-to-parallel conversion chip, and it achieves high-speed data communication between the system and host computer through the USB3.0 bus. The experimental results show that the developed PC software realizes the real-time display of 14-bit LVDS original image after 14-to-8 bit conversion and JPEG2000 compressed image after decompression in software, and can realize the real-time display of the acquired laser signal data. The correctness of the test system design is verified, indicating that the interface link is normal.

Multiphoton microscopy system with a compact fiber-based femtosecond-pulse laser and handheld probe

PubMed Central

Liu, Gangjun; Kieu, Khanh; Wise, Frank W.; Chen, Zhongping

2012-01-01

We report on the development of a compact multiphoton microscopy (MPM) system that integrates a compact and robust fiber laser with a miniature probe. The all normal dispersion fiber femtosecond laser has a central wavelength of 1.06 μm, pulse width of 125 fs and average power of more than 1 W. A double cladding photonic crystal fiber was used to deliver the excitation beam and to collect the two-photon signal. The hand-held probe included galvanometer-based mirror scanners, relay lenses and a focusing lens. The packaged probe had a diameter of 16 mm. Second harmonic generation (SHG) images and two-photon excited fluorescence (TPEF) images of biological tissues were demonstrated using the system. MPM images of different biological tissues acquired by the compact system which integrates an FBFP laser, an DCPCF and a miniature handheld probe. PMID:20635426

A Completely Solid-State Tunable Ti:Sapphire Laser System

NASA Technical Reports Server (NTRS)

Guerra, David V.; Coyle, D. Barry; Krebs, Danny J.

1994-01-01

Compact, completely solid-state tunable pulsed laser system passively cooled developed for potential employment in aircraft and sounding-rocket lidar experiments. Ti:sapphire based laser system pumped with frequency-doubled diode-pumped Nd:YAG. Rugged, self-contained system extremely flexible and provides pulsed output at specific frequencies with low input-power requirements. In-situ measurements enables scientists to study upper-atmosphere dynamics. Tuning range easily extended to bands between 650-950 nm in order to study other atmospheric constituents.

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.

A high-precision velocity measuring system design for projectiles based on S-shaped laser screen

NASA Astrophysics Data System (ADS)

Liu, Huayi; Qian, Zheng; Yu, Hao; Li, Yutao

2018-03-01

The high-precision measurement of the velocity of high-speed flying projectile is of great significance for the evaluation and development of modern weapons. The velocity of the high-speed flying projectile is usually measured by laser screen velocity measuring system. But this method cannot achieve the repeated measurements, so we cannot make an indepth evaluation of the uncertainty about the measuring system. This paper presents a design based on S-shaped laser screen velocity measuring system. This design can achieve repeated measurements. Therefore, it can effectively reduce the uncertainty of the velocity measuring system. In addition, we made a detailed analysis of the uncertainty of the measuring system. The measurement uncertainty is 0.2% when the velocity of the projectile is about 200m/s.

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.

Rapid prototyping of reflectors for vehicle lighting using laser activated remote phosphor

NASA Astrophysics Data System (ADS)

Lachmayer, Roland; Kloppenburg, Gerolf; Wolf, Alexander

2015-03-01

Bright white light sources are of significant importance for automotive front lighting systems. Today's upper class vehicles mainly use HID or LED as light source. As a further step in this development laser diode based systems offer high luminance, efficiency and allow the realization of new styling concepts and new dynamic lighting functions. These white laser diode systems can either be realized by mixing different spectral sources or by combining diodes with specific phosphors. Based on the approach of generating light using a laser and remote phosphor, lighting modules are manufactured. Four blue laser diodes (450 nm) are used to activate a phosphor coating and thus to achieve white light. A segmented paraboloid reflector generates the desired light distribution for an additional car headlamp. We use high speed milling and selective laser melting to build the reflector system for this lighting module. We compare the spectral reflection grade of these materials. Furthermore the generated modules are analyzed regarding their efficiency and light distribution. The use of Rapid Prototyping technologies allows an early validation of the chosen concept and is supposed to reduce cost and time in the product development process significantly. Therefor we discuss costs and times of the applied manufacturing technologies.

[Analysis and experimental verification of sensitivity and SNR of laser warning receiver].

PubMed

Zhang, Ji-Long; Wang, Ming; Tian, Er-Ming; Li, Xiao; Wang, Zhi-Bin; Zhang, Yue

2009-01-01

In order to countermeasure increasingly serious threat from hostile laser in modern war, it is urgent to do research on laser warning technology and system, and the sensitivity and signal to noise ratio (SNR) are two important performance parameters in laser warning system. In the present paper, based on the signal statistical detection theory, a method for calculation of the sensitivity and SNR in coherent detection laser warning receiver (LWR) has been proposed. Firstly, the probabilities of the laser signal and receiver noise were analyzed. Secondly, based on the threshold detection theory and Neyman-Pearson criteria, the signal current equation was established by introducing detection probability factor and false alarm rate factor, then, the mathematical expressions of sensitivity and SNR were deduced. Finally, by using method, the sensitivity and SNR of the sinusoidal grating laser warning receiver developed by our group were analyzed, and the theoretic calculation and experimental results indicate that the SNR analysis method is feasible, and can be used in performance analysis of LWR.

All-fiber optical parametric oscillator for bio-medical imaging applications

NASA Astrophysics Data System (ADS)

Gottschall, Thomas; Meyer, Tobias; Jauregui, Cesar; Just, Florian; Eidam, Tino; Schmitt, Michael; Popp, Jürgen; Limpert, Jens; Tünnermann, Andreas

2017-02-01

Among other modern imaging techniques, stimulated Raman Scattering (SRS) requires an extremely quiet, widely wavelength tunable laser, which, up to now, is unheard of in fiber laser systems. We present a compact all-fiber laser system, which features an optical parametric oscillator (OPO) based on degenerate four-wave mixing (FWM) in an endlessly single-mode photonic-crystal fiber. We employ an all-fiber frequency and repetition rate tunable laser in order to enable wideband conversion in the linear OPO cavity arrangement, the signal and idler radiation can be tuned between 764 and 960 nm and 1164 and 1552 nm at 9.5 MHz. Thus, all biochemically relevant Raman shifts between 922 and 3322 cm-1 may be addressed in combination with a secondary output, which is tunable between 1024 and 1052 nm. This ultra-low noise output emits synchronized pulses with twice the repetition rate to enable SRS imaging. We measure the relative intensity noise of this output beam at 9.5 MHz to be between -145 and -148 dBc, which is low enough to enable high-speed SRS imaging with a good signal-to-noise ratio. The laser system is computer controlled to access a certain energy differences within one second. Combining FWM based conversion, with all-fiber Yb-based fiber lasers enables the construction of the first automated, turn-key and widely tunable fiber laser. This laser concept could be the missing piece to establish CRS imaging as a reliable guiding tool for clinical diagnostics and surgical guidance.

Beam shaping for laser-based adaptive optics in astronomy.

PubMed

Béchet, Clémentine; Guesalaga, Andrés; Neichel, Benoit; Fesquet, Vincent; González-Núñez, Héctor; Zúñiga, Sebastián; Escarate, Pedro; Guzman, Dani

2014-06-02

The availability and performance of laser-based adaptive optics (AO) systems are strongly dependent on the power and quality of the laser beam before being projected to the sky. Frequent and time-consuming alignment procedures are usually required in the laser systems with free-space optics to optimize the beam. Despite these procedures, significant distortions of the laser beam have been observed during the first two years of operation of the Gemini South multi-conjugate adaptive optics system (GeMS). A beam shaping concept with two deformable mirrors is investigated in order to provide automated optimization of the laser quality for astronomical AO. This study aims at demonstrating the correction of quasi-static aberrations of the laser, in both amplitude and phase, testing a prototype of this two-deformable mirror concept on GeMS. The paper presents the results of the preparatory study before the experimental phase. An algorithm to control amplitude and phase correction, based on phase retrieval techniques, is presented with a novel unwrapping method. Its performance is assessed via numerical simulations, using aberrations measured at GeMS as reference. The results predict effective amplitude and phase correction of the laser distortions with about 120 actuators per mirror and a separation of 1.4 m between the mirrors. The spot size is estimated to be reduced by up to 15% thanks to the correction. In terms of AO noise level, this has the same benefit as increasing the photon flux by 40%.

Resonance energy transfer process in nanogap-based dual-color random lasing

NASA Astrophysics Data System (ADS)

Shi, Xiaoyu; Tong, Junhua; Liu, Dahe; Wang, Zhaona

2017-04-01

The resonance energy transfer (RET) process between Rhodamine 6G and oxazine in the nanogap-based random systems is systematically studied by revealing the variations and fluctuations of RET coefficients with pump power density. Three working regions stable fluorescence, dynamic laser, and stable laser are thus demonstrated in the dual-color random systems. The stable RET coefficients in fluorescence and lasing regions are generally different and greatly dependent on the donor concentration and the donor-acceptor ratio. These results may provide a way to reveal the energy distribution regulars in the random system and to design the tunable multi-color coherent random lasers for colorful imaging.

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

Soviet chemical laser research: pulsed lasers. Report for 1963--1970

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

Ksander, Y.

1971-11-01

The document reviews Soviet work on pulsed chemical lasers published in the open litarature in 1963-1970. Whereas U. S. research combines the approaches of physics, quantum electrodynamics, and aerodynamics, Soviet laser research is heavily (and expertly) oriented to understanding the chemical reactions. They prefer pulsed to cw systems, concentrating on kinetics of vibrationally excited diatomic systems. The documents describe gas lasers with discharge, photolytic, and other initiation and includes research on HN/sub 3/ + CO/sub 2/ mixtures, and means of controlling reaction rates by resonant coupling and selective heating. The report also proposes a laser based on photorecombination of atoms.

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.

Adiabatic Soliton Laser

NASA Astrophysics Data System (ADS)

Bednyakova, Anastasia; Turitsyn, Sergei K.

2015-03-01

The key to generating stable optical pulses is mastery of nonlinear light dynamics in laser resonators. Modern techniques to control the buildup of laser pulses are based on nonlinear science and include classical solitons, dissipative solitons, parabolic pulses (similaritons) and various modifications and blending of these methods. Fiber lasers offer remarkable opportunities to apply one-dimensional nonlinear science models for the design and optimization of very practical laser systems. Here, we propose a new concept of a laser based on the adiabatic amplification of a soliton pulse in the cavity—the adiabatic soliton laser. The adiabatic change of the soliton parameters during evolution in the resonator relaxes the restriction on the pulse energy inherent in traditional soliton lasers. Theoretical analysis is confirmed by extensive numerical modeling.

In vivo soft tissue differentiation by diffuse reflectance spectroscopy: preliminary results

NASA Astrophysics Data System (ADS)

Zam, Azhar; Stelzle, Florian; Tangermann-Gerk, Katja; Adler, Werner; Nkenke, Emeka; Neukam, Friedrich Wilhelm; Schmidt, Michael; Douplik, Alexandre

Remote laser surgery does not provide haptic feedback to operate layer by layer and preserve vulnerable anatomical structures like nerve tissue or blood vessels. The aim of this study is identification of soft tissue in vivo by diffuse reflectance spectroscopy to set the base for a feedback control system to enhance nerve preservation in oral and maxillofacial laser surgery. Various soft tissues can be identified by diffuse reflectance spectroscopy in vivo. The results may set the base for a feedback system to prevent nerve damage during oral and maxillofacial laser surgery.

High contrast research in the Nd:glass laser system based on optical parametric amplification temporal cleaning device

NASA Astrophysics Data System (ADS)

Lu, Xiaoming; Leng, Yuxin; Sui, Zhan; Li, Yanyan; Zhang, Zongxin; Xu, Yi; Guo, Xiaoyang; Liu, Yanqi; Li, Ruxin; Xu, Zhizhan

2014-02-01

We demonstrate high amplified spontaneous emission (ASE) contrast pulses in a Nd:glass laser system based on the hybrid double chirped pulse amplification (double CPA) scheme. By an OPA temporal cleaning device, ~100 uJ/46 fs/ 1011 clean pulses are generated and amplified in the next Nd:glass laser. After compressor, >150 mJ/~0.5 ps/1 Hz pulses can be obtained. The ASE temporal contrast of amplified pulses is ~1011 with energy gain ~2.5×104 in the Nd:glass amplifiers.

A Virtual Blind Cane Using a Line Laser-Based Vision System and an Inertial Measurement Unit

PubMed Central

Dang, Quoc Khanh; Chee, Youngjoon; Pham, Duy Duong; Suh, Young Soo

2016-01-01

A virtual blind cane system for indoor application, including a camera, a line laser and an inertial measurement unit (IMU), is proposed in this paper. Working as a blind cane, the proposed system helps a blind person find the type of obstacle and the distance to it. The distance from the user to the obstacle is estimated by extracting the laser coordinate points on the obstacle, as well as tracking the system pointing angle. The paper provides a simple method to classify the obstacle’s type by analyzing the laser intersection histogram. Real experimental results are presented to show the validity and accuracy of the proposed system. PMID:26771618

Closed-cycle gas dynamic laser design investigation

NASA Technical Reports Server (NTRS)

Ketch, G. W.; Young, W. E.

1977-01-01

A conceptual design study was made of a closed cycle gas-dynamic laser to provide definition of the major components in the laser loop. The system potential application is for long range power transmission by way of high power laser beams to provide satellite propulsion energy for orbit changing or station keeping. A parametric cycle optimization was conducted to establish the thermodynamic requirements for the system components. A conceptual design was conducted of the closed cycle system and the individual components to define physical characteristics and establish the system size and weight. Technology confirmation experimental demonstration programs were outlined to develop, evaluate, and demonstrate the technology base needed for this closed cycle GDL system.

A computer system to be used with laser-based endoscopy for quantitative diagnosis of early gastric cancer.

PubMed

Miyaki, Rie; Yoshida, Shigeto; Tanaka, Shinji; Kominami, Yoko; Sanomura, Yoji; Matsuo, Taiji; Oka, Shiro; Raytchev, Bisser; Tamaki, Toru; Koide, Tetsushi; Kaneda, Kazufumi; Yoshihara, Masaharu; Chayama, Kazuaki

2015-02-01

To evaluate the usefulness of a newly devised computer system for use with laser-based endoscopy in differentiating between early gastric cancer, reddened lesions, and surrounding tissue. Narrow-band imaging based on laser light illumination has come into recent use. We devised a support vector machine (SVM)-based analysis system to be used with the newly devised endoscopy system to quantitatively identify gastric cancer on images obtained by magnifying endoscopy with blue-laser imaging (BLI). We evaluated the usefulness of the computer system in combination with the new endoscopy system. We evaluated the system as applied to 100 consecutive early gastric cancers in 95 patients examined by BLI magnification at Hiroshima University Hospital. We produced a set of images from the 100 early gastric cancers; 40 flat or slightly depressed, small, reddened lesions; and surrounding tissues, and we attempted to identify gastric cancer, reddened lesions, and surrounding tissue quantitatively. The average SVM output value was 0.846 ± 0.220 for cancerous lesions, 0.381 ± 0.349 for reddened lesions, and 0.219 ± 0.277 for surrounding tissue, with the SVM output value for cancerous lesions being significantly greater than that for reddened lesions or surrounding tissue. The average SVM output value for differentiated-type cancer was 0.840 ± 0.207 and for undifferentiated-type cancer was 0.865 ± 0.259. Although further development is needed, we conclude that our computer-based analysis system used with BLI will identify gastric cancers quantitatively.

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.

Picosecond laser welding of similar and dissimilar materials.

PubMed

Carter, Richard M; Chen, Jianyong; Shephard, Jonathan D; Thomson, Robert R; Hand, Duncan P

2014-07-01

We report picosecond laser welding of similar and dissimilar materials based on plasma formation induced by a tightly focused beam from a 1030 nm, 10 ps, 400 kHz laser system. Specifically, we demonstrate the welding of fused silica, borosilicate, and sapphire to a range of materials including borosilicate, fused silica, silicon, copper, aluminum, and stainless steel. Dissimilar material welding of glass to aluminum and stainless steel has not been previously reported. Analysis of the borosilicate-to-borosilicate weld strength compares well to those obtained using similar welding systems based on femtosecond lasers. There is, however, a strong requirement to prepare surfaces to a high (10-60 nm Ra) flatness to ensure a successful weld.

Infrared-laser-based fundus angiography

NASA Astrophysics Data System (ADS)

Klingbeil, Ulrich; Canter, Joseph M.; Lesiecki, Michael L.; Reichel, Elias

1994-06-01

Infrared fundus angiography, using the fluorescent dye indocyanine green (ICG), has shown great potential in delineating choroidal neovascularization (CNV) otherwise not detectable. A digital retinal imaging system containing a diode laser for illumination has been developed and optimized to perform high sensitivity ICG angiography. The system requires less power and generates less pseudo-fluorescence background than nonlaser devices. During clinical evaluation at three retinal centers more than 200 patients, the majority of which had age-related macular degeneration, were analyzed. Laser based ICG angiography was successful in outlining many of the ill-defined or obscure CNV as defined by fluorescein angiography. The procedure was not as successful with classic CNV. ICG angiograms were used to prepare and guide laser treatment.

Spectroscopy of 171Yb in an optical lattice based on laser linewidth transfer using a narrow linewidth frequency comb.

PubMed

Inaba, Hajime; Hosaka, Kazumoto; Yasuda, Masami; Nakajima, Yoshiaki; Iwakuni, Kana; Akamatsu, Daisuke; Okubo, Sho; Kohno, Takuya; Onae, Atsushi; Hong, Feng-Lei

2013-04-08

We propose a novel, high-performance, and practical laser source system for optical clocks. The laser linewidth of a fiber-based frequency comb is reduced by phase locking a comb mode to an ultrastable master laser at 1064 nm with a broad servo bandwidth. A slave laser at 578 nm is successively phase locked to a comb mode at 578 nm with a broad servo bandwidth without any pre-stabilization. Laser frequency characteristics such as spectral linewidth and frequency stability are transferred to the 578-nm slave laser from the 1064-nm master laser. Using the slave laser, we have succeeded in observing the clock transition of (171)Yb atoms confined in an optical lattice with a 20-Hz spectral linewidth.

Compact atom interferometer using single laser

NASA Astrophysics Data System (ADS)

Chiow, Sheng-Wey; Yu, Nan

2017-04-01

Atom interferometer (AI) based sensors exhibit precision and accuracy unattainable with classical sensors, thanks to the inherent stability of atomic properties. The complexity of required laser system and the size of vacuum chamber driven by optical access requirement limit the applicability of such technology in size, weight, and power (SWaP) challenging environments, such as in space. For instance, a typical physics package of AI includes six viewports for laser cooling and trapping, two for AI beams, and two more for detection and a vacuum pump. Similarly, a typical laser system for an AI includes two lasers for cooling and repumping, and two for Raman transitions as AI beam splitters. In this presentation, we report our efforts in developing a miniaturized atomic accelerometer for planetary exploration. We will describe a physics package configuration having minimum optical access (thus small volume), and a laser and optics system utilizing a single laser for the sensor operation. Preliminary results on acceleration sensitivity will be discussed. We will also illustrate a path for further packaging and integration based on the demonstrated concepts. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Some emerging applications of lasers

NASA Astrophysics Data System (ADS)

Christensen, C. P.

1982-10-01

Applications of lasers in photochemistry, advanced instrumentation, and information storage are discussed. Laser microchemistry offers a number of new methods for altering the morphology of a solid surface with high spatial resolution. Recent experiments in material deposition, material removal, and alloying and doping are reviewed. A basic optical disk storage system is described and the problems faced by this application are discussed, in particular those pertaining to recording media. An advanced erasable system based on the magnetooptic effect is described. Applications of lasers for remote sensing are discussed, including various lidar systems, the use of laser-induced fluorescence for oil spill characterization and uranium exploration, and the use of differential absorption for detection of atmospheric constituents, temperature, and humidity.

Intravital multiphoton fluorescence imaging and optical manipulation of spinal cord in mice, using a compact fiber laser system.

PubMed

Oshima, Yusuke; Horiuch, Hideki; Honkura, Naoki; Hikita, Atsuhiko; Ogata, Tadanori; Miura, Hiromasa; Imamura, Takeshi

2014-09-01

Near-infrared ultrafast lasers are widely used for multiphoton excited fluorescence microscopy in living animals. Ti:Sapphire lasers are typically used for multiphoton excitation, but their emission wavelength is restricted below 1,000 nm. The aim of this study is to evaluate the performance of a compact Ytterbium-(Yb-) fiber laser at 1,045 nm for multiphoton excited fluorescence microscopy in spinal cord injury. In this study, we employed a custom-designed microscopy system with a compact Yb-fiber laser and evaluated the performance of this system in in vivo imaging of brain cortex and spinal cord in YFP-H transgenic mice. For in vivo imaging of brain cortex, sharp images of basal dendrites, and pyramidal cells expressing EYFP were successfully captured using the Yb-fiber laser in our microscopy system. We also performed in vivo imaging of axon fibers of spinal cord in the transgenic mice. The obtained images were almost as sharp as those obtained using a conventional ultrafast laser system. In addition, laser ablation and multi-color imaging could be performed simultaneously using the Yb-fiber laser. The high-peak pulse Yb-fiber laser is potentially useful for multimodal bioimaging methods based on a multiphoton excited fluorescence microscopy system that incorporates laser ablation techniques. Our results suggest that microscopy systems of this type could be utilized in studies of neuroscience and clinical use in diagnostics and therapeutic tool for spinal cord injury in the future. © 2014 Wiley Periodicals, Inc.

Bridge Displacement Monitoring Method Based on Laser Projection-Sensing Technology

PubMed Central

Zhao, Xuefeng; Liu, Hao; Yu, Yan; Xu, Xiaodong; Hu, Weitong; Li, Mingchu; Ou, Jingping

2015-01-01

Bridge displacement is the most basic evaluation index of the health status of a bridge structure. The existing measurement methods for bridge displacement basically fail to realize long-term and real-time dynamic monitoring of bridge structures, because of the low degree of automation and the insufficient precision, causing bottlenecks and restriction. To solve this problem, we proposed a bridge displacement monitoring system based on laser projection-sensing technology. First, the laser spot recognition method was studied. Second, the software for the displacement monitoring system was developed. Finally, a series of experiments using this system were conducted, and the results show that such a system has high measurement accuracy and speed. We aim to develop a low-cost, high-accuracy and long-term monitoring method for bridge displacement based on these preliminary efforts. PMID:25871716

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.

Multi-kW single fiber laser based on an extra large mode area fiber design

NASA Astrophysics Data System (ADS)

Langner, Andreas; Such, Mario; Schötz, Gerhard; Just, Florian; Leich, Martin; Schwuchow, Anka; Grimm, Stephan; Zimer, Hagen; Kozak, Marcin; Wedel, Björn; Rehmann, Georg; Bachert, Charley; Krause, Volker

2012-02-01

The quality of Yb-doped fused bulk silica produced by sintering of Yb-doped fused silica granulates has improved greatly in the past five years [1 - 4]. In particular, the refractive index and doping level homogeneity of such materials are excellent and we achieved excellent background fiber attenuation of the active core material down to about 20 dB/km at 1200 nm. The improvement of the Yb-doped fused bulk silica has enabled the development of multi-kW fiber laser systems based on a single extra large multimode laser fiber (XLMA fiber). When a single active fiber is used in combination with the XLMA multimode fiber of 1200 μm diameter simple and robust high power fiber laser setups without complex fiber coupling and fiber combiner systems become possible. In this papper, we will discuss in detail the development of the core material based on Yb-doped bulk silica and the characterization of Yb-doped fibers with different core compositions. We will also report on the excellent performance of a 4 kW fiber laser based on a single XLMA-fiber and show the first experimental welding results of steel sheets achieved with such a laser.

Developments in holographic-based scanner designs

NASA Astrophysics Data System (ADS)

Rowe, David M.

1997-07-01

Holographic-based scanning systems have been used for years in the high resolution prepress markets where monochromatic lasers are generally utilized. However, until recently, due to the dispersive properties of holographic optical elements (HOEs), along with the high cost associated with recording 'master' HOEs, holographic scanners have not been able to penetrate major scanning markets such as the laser printer and digital copier markets, low to mid-range imagesetter markets, and the non-contact inspection scanner market. Each of these markets has developed cost effective laser diode based solutions using conventional scanning approaches such as polygon/f-theta lens combinations. In order to penetrate these markets, holographic-based systems must exhibit low cost and immunity to wavelength shifts associated with laser diodes. This paper describes recent developments in the design of holographic scanners in which multiple HOEs, each possessing optical power, are used in conjunction with one curved mirror to passively correct focal plane position errors and spot size changes caused by the wavelength instability of laser diodes. This paper also describes recent advancements in low cost production of high quality HOEs and curved mirrors. Together these developments allow holographic scanners to be economically competitive alternatives to conventional devices in every segment of the laser scanning industry.

Laser tissue coagulation and concurrent optical coherence tomography through a double-clad fiber coupler.

PubMed

Beaudette, Kathy; Baac, Hyoung Won; Madore, Wendy-Julie; Villiger, Martin; Godbout, Nicolas; Bouma, Brett E; Boudoux, Caroline

2015-04-01

Double-clad fiber (DCF) is herein used in conjunction with a double-clad fiber coupler (DCFC) to enable simultaneous and co-registered optical coherence tomography (OCT) and laser tissue coagulation. The DCF allows a single channel fiber-optic probe to be shared: i.e. the core propagating the OCT signal while the inner cladding delivers the coagulation laser light. We herein present a novel DCFC designed and built to combine both signals within a DCF (>90% of single-mode transmission; >65% multimode coupling). Potential OCT imaging degradation mechanisms are also investigated and solutions to mitigate them are presented. The combined DCFC-based system was used to induce coagulation of an ex vivo swine esophagus allowing a real-time assessment of thermal dynamic processes. We therefore demonstrate a DCFC-based system combining OCT imaging with laser coagulation through a single fiber, thus enabling both modalities to be performed simultaneously and in a co-registered manner. Such a system enables endoscopic image-guided laser marking of superficial epithelial tissues or laser thermal therapy of epithelial lesions in pathologies such as Barrett's esophagus.

Laser tissue coagulation and concurrent optical coherence tomography through a double-clad fiber coupler

PubMed Central

Beaudette, Kathy; Baac, Hyoung Won; Madore, Wendy-Julie; Villiger, Martin; Godbout, Nicolas; Bouma, Brett E.; Boudoux, Caroline

2015-01-01

Double-clad fiber (DCF) is herein used in conjunction with a double-clad fiber coupler (DCFC) to enable simultaneous and co-registered optical coherence tomography (OCT) and laser tissue coagulation. The DCF allows a single channel fiber-optic probe to be shared: i.e. the core propagating the OCT signal while the inner cladding delivers the coagulation laser light. We herein present a novel DCFC designed and built to combine both signals within a DCF (>90% of single-mode transmission; >65% multimode coupling). Potential OCT imaging degradation mechanisms are also investigated and solutions to mitigate them are presented. The combined DCFC-based system was used to induce coagulation of an ex vivo swine esophagus allowing a real-time assessment of thermal dynamic processes. We therefore demonstrate a DCFC-based system combining OCT imaging with laser coagulation through a single fiber, thus enabling both modalities to be performed simultaneously and in a co-registered manner. Such a system enables endoscopic image-guided laser marking of superficial epithelial tissues or laser thermal therapy of epithelial lesions in pathologies such as Barrett’s esophagus. PMID:25909013

Study on the high-frequency laser measurement of slot surface difference

NASA Astrophysics Data System (ADS)

Bing, Jia; Lv, Qiongying; Cao, Guohua

2017-10-01

In view of the measurement of the slot surface difference in the large-scale mechanical assembly process, Based on high frequency laser scanning technology and laser detection imaging principle, This paragraph designs a double galvanometer pulse laser scanning system. Laser probe scanning system architecture consists of three parts: laser ranging part, mechanical scanning part, data acquisition and processing part. The part of laser range uses high-frequency laser range finder to measure the distance information of the target shape and get a lot of point cloud data. Mechanical scanning part includes high-speed rotary table, high-speed transit and related structure design, in order to realize the whole system should be carried out in accordance with the design of scanning path on the target three-dimensional laser scanning. Data processing part mainly by FPGA hardware with LAbVIEW software to design a core, to process the point cloud data collected by the laser range finder at the high-speed and fitting calculation of point cloud data, to establish a three-dimensional model of the target, so laser scanning imaging is realized.

Review Of Laser Lightcraft Propulsion System

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

Davis, Eric W.; Mead, Franklin B. Jr

Laser-powered 'Lightcraft' systems that deliver nano-satellites to LEO have been studied for the Air Force Research Laboratory (AFRL). The study was built on the extensive Lightcraft laser propulsion technology already developed by theoretical and experimental work by the AFRL's Propulsion Directorate at Edwards AFB, CA. Here we review the history and engineering-physics of the laser Lightcraft system and its propulsive performance. We will also review the effectiveness and cost of a Lightcraft vehicle powered by a high-energy laser beam. One result of this study is the significant influence of laser wavelength on the power lost during laser beam propagation throughmore » Earth's atmosphere and in space. It was discovered that energy and power losses in the laser beam are extremely sensitive to wavelength for Earth-To-Orbit missions, and this significantly affects the amount of mass that can be placed into orbit for a given maximum amount of radiated power from a ground-based laser.« less

Systems analysis on laser beamed power

NASA Technical Reports Server (NTRS)

Zeiders, Glenn W., Jr.

1993-01-01

The NASA SELENE power beaming program is intended to supply cost-effective power to space assets via Earth-based lasers and active optics systems. Key elements of the program are analyzed, the overall effort is reviewed, and recommendations are presented.

970-nm ridge waveguide diode laser bars for high power DWBC systems

NASA Astrophysics Data System (ADS)

Wilkens, Martin; Erbert, Götz; Wenzel, Hans; Knigge, Andrea; Crump, Paul; Maaßdorf, Andre; Fricke, Jörg; Ressel, Peter; Strohmaier, Stephan; Schmidt, Berthold; Tränkle, Günther

2018-02-01

de lasers are key components in material processing laser systems. While mostly used as pump sources for solid state or fiber lasers, direct diode laser systems using dense wavelength multiplexing have come on the market in recent years. These systems are realized with broad area lasers typically, resulting in beam quality inferior to disk or fiber lasers. We will present recent results of highly efficient ridge waveguide (RW) lasers, developed for dense-wavelength-beamcombining (DWBC) laser systems expecting beam qualities comparable to solid state laser systems and higher power conversion efficiencies (PCE). The newly developed RW lasers are based on vertical structures with an extreme double asymmetric large optical cavity. Besides a low vertical divergence these structures are suitable for RW-lasers with (10 μm) broad ridges, emitting in a single mode with a good beam quality. The large stripe width enables a lateral divergence below 10° (95 % power content) and a high PCE by a comparably low series resistance. We present results of single emitters and small test arrays under different external feedback conditions. Single emitters can be tuned from 950 nm to 975 nm and reach 1 W optical power with more than 55 % PCE and a beam quality of M2 < 2 over the full wavelength range. The spectral width is below 30 pm FWHM. 5 emitter arrays were stabilized using the same setup. Up to now we reached 3 W optical power, limited by power supply, with 5 narrow spectral lines.

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.

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.

Aircraft Detection System Ensures Free-Space Laser Safety

NASA Technical Reports Server (NTRS)

Smithgall, Brian; Wilson, Keith E.

2004-01-01

As scientists continue to explore our solar system, there are increasing demands to return greater volumes of data from smaller deep-space probes. Accordingly, NASA is studying advanced strategies based on free-space laser transmissions, which offer secure, high-bandwidth communications using smaller subsystems of much lower power and mass than existing ones. These approaches, however, can pose a danger to pilots in the beam path because the lasers may illuminate aircraft and blind them. Researchers thus are investigating systems that will monitor the surrounding airspace for aircraft that could be affected. This paper presents current methods for safe free space laser propagation.

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.

In-vitro and clinical evaluation of transurethral laser-induced prostatectomy (TULIP)

NASA Astrophysics Data System (ADS)

van Swol, Christiaan F. P.; Verdaasdonck, Rudolf M.; Mooibroek, Jaap; Boon, Tom A.

1993-05-01

Transurethral ultrasound-guided laser induced prostatectomy (TULIP) is a recent development in the treatment of benign prostatic hyperplasia. The system is based upon Nd:YAG laser irradiation delivered by a right angled fiber. The dosimetry used in a clinical situation is mostly based upon animal studies. In this study, the light and temperature distribution in the prostate during Nd:YAG laser irradiation were modeled using Monte Carlo and finite differences theory. The results of this model were compared with in vitro experiments. The influence of the different parameters involved, e.g., the scanning speed and the power of the laser beam, were evaluated. Initial results show the temperature distribution and thus the therapeutic effect of the TULIP procedure. Until now 36 patients have been treated successfully. The mean in-hospital time was somewhat shorter than for a TURP treatment while the results were comparable. These treatments, however, show the need for a better understanding of the mechanisms involved. Modeling and subsequent in vitro and in vivo measurements might improve the understanding and safe and successful application of prostate treatment using laser based systems.

Development of sub-100 femtosecond timing and synchronization system

NASA Astrophysics Data System (ADS)

Lin, Zhenyang; Du, Yingchao; Yang, Jin; Xu, Yilun; Yan, Lixin; Huang, Wenhui; Tang, Chuanxiang; Huang, Gang; Du, Qiang; Doolittle, Lawrence; Wilcox, Russell; Byrd, John

2018-01-01

The precise timing and synchronization system is an essential part for the ultra-fast electron and X-ray sources based on the photocathode injector where strict synchronization among RF, laser, and beams are required. In this paper, we present an integrated sub-100 femtosecond timing and synchronization system developed and demonstrated recently in Tsinghua University based on the collaboration with Lawrence Berkeley National Lab. The timing and synchronization system includes the fiber-based CW carrier phase reference distribution system for delivering stabilized RF phase reference to multiple receiver clients, the Low Level RF (LLRF) control system to monitor and generate the phase and amplitude controllable pulse RF signal, and the laser-RF synchronization system for high precision synchronization between optical and RF signals. Each subsystem is characterized by its blocking structure and is also expansible. A novel asymmetric calibration sideband signal method was proposed for eliminating the non-linear distortion in the optical synchronization process. According to offline and online tests, the system can deliver a stable signal to each client and suppress the drift and jitter of the RF signal for the accelerator and the laser oscillator to less than 100 fs RMS (˜0.1° in 2856 MHz frequency). Moreover, a demo system with a LLRF client and a laser-RF synchronization client is deployed and operated successfully at the Tsinghua Thomson scattering X-ray source. The beam-based jitter measurement experiments have been conducted to evaluate the overall performance of the system, and the jitter sources are discussed.

Development of sub-100 femtosecond timing and synchronization system.

PubMed

Lin, Zhenyang; Du, Yingchao; Yang, Jin; Xu, Yilun; Yan, Lixin; Huang, Wenhui; Tang, Chuanxiang; Huang, Gang; Du, Qiang; Doolittle, Lawrence; Wilcox, Russell; Byrd, John

2018-01-01

The precise timing and synchronization system is an essential part for the ultra-fast electron and X-ray sources based on the photocathode injector where strict synchronization among RF, laser, and beams are required. In this paper, we present an integrated sub-100 femtosecond timing and synchronization system developed and demonstrated recently in Tsinghua University based on the collaboration with Lawrence Berkeley National Lab. The timing and synchronization system includes the fiber-based CW carrier phase reference distribution system for delivering stabilized RF phase reference to multiple receiver clients, the Low Level RF (LLRF) control system to monitor and generate the phase and amplitude controllable pulse RF signal, and the laser-RF synchronization system for high precision synchronization between optical and RF signals. Each subsystem is characterized by its blocking structure and is also expansible. A novel asymmetric calibration sideband signal method was proposed for eliminating the non-linear distortion in the optical synchronization process. According to offline and online tests, the system can deliver a stable signal to each client and suppress the drift and jitter of the RF signal for the accelerator and the laser oscillator to less than 100 fs RMS (∼0.1° in 2856 MHz frequency). Moreover, a demo system with a LLRF client and a laser-RF synchronization client is deployed and operated successfully at the Tsinghua Thomson scattering X-ray source. The beam-based jitter measurement experiments have been conducted to evaluate the overall performance of the system, and the jitter sources are discussed.

Synchronized femtosecond laser pulse switching system based nano-patterning technology

NASA Astrophysics Data System (ADS)

Sohn, Ik-Bu; Choi, Hun-Kook; Yoo, Dongyoon; Noh, Young-Chul; Sung, Jae-Hee; Lee, Seong-Ku; Ahsan, Md. Shamim; Lee, Ho

2017-07-01

This paper demonstrates the design and development of a synchronized femtosecond laser pulse switching system and its applications in nano-patterning of transparent materials. Due to synchronization, we are able to control the location of each irradiated laser pulse in any kind of substrate. The control over the scanning speed and scanning step of the laser beam enables us to pattern periodic micro/nano-metric holes, voids, and/or lines in various materials. Using the synchronized laser system, we pattern synchronized nano-holes on the surface of and inside various transparent materials including fused silica glass and polymethyl methacrylate to replicate any image or pattern on the surface of or inside (transparent) materials. We also investigate the application areas of the proposed synchronized femtosecond laser pulse switching system in a diverse field of science and technology, especially in optical memory, color marking, and synchronized micro/nano-scale patterning of materials.

Integrated Laser Characterization, Data Acquisition, and Command and Control Test System

NASA Technical Reports Server (NTRS)

Stysley, Paul; Coyle, Barry; Lyness, Eric

2012-01-01

Satellite-based laser technology has been developed for topographical measurements of the Earth and of other planets. Lasers for such missions must be highly efficient and stable over long periods in the temperature variations of orbit. In this innovation, LabVIEW is used on an Apple Macintosh to acquire and analyze images of the laser beam as it exits the laser cavity to evaluate the laser s performance over time, and to monitor and control the environmental conditions under which the laser is tested. One computer attached to multiple cameras and instruments running LabVIEW-based software replaces a conglomeration of computers and software packages, saving hours in maintenance and data analysis, and making very longterm tests possible. This all-in-one system was written primarily using LabVIEW for Mac OS X, which allows the combining of data from multiple RS-232, USB, and Ethernet instruments for comprehensive laser analysis and control. The system acquires data from CCDs (charge coupled devices), power meters, thermistors, and oscilloscopes over a controllable period of time. This data is saved to an html file that can be accessed later from a variety of data analysis programs. Also, through the LabVIEW interface, engineers can easily control laser input parameters such as current, pulse width, chiller temperature, and repetition rates. All of these parameters can be adapted and cycled over a period of time.

High-energy master oscillator power amplifier with near-diffraction-limited output based on ytterbium-doped PCF fiber

NASA Astrophysics Data System (ADS)

Li, Rao; Qiao, Zhi; Wang, Xiaochao; Fan, Wei; Lin, Zunqi

2017-10-01

With the development of fiber technologies, fiber lasers are able to deliver very high power beams and high energy pulses which can be used not only in scientific researches but industrial fields (laser marking, welding,…). The key of high power fiber laser is fiber amplifier. In this paper, we present a two-level master-oscillator power amplifier system at 1053 nm based on Yb-doped photonic crystal fibers. The system is used in the front-end of high power laser facility for the amplification of nano-second pulses to meet the high-level requirements. Thanks to the high gain of the system which is over 50 dB, the pulse of more than 0.89 mJ energy with the nearly diffraction-limited beam quality has been obtained.

Analytical Study on Flight Performance of a RP Laser Launcher

NASA Astrophysics Data System (ADS)

Katsurayama, H.; Ushio, M.; Komurasaki, K.; Arakawa, Y.

2005-04-01

An air-breathing RP Laser Launcher has been proposed as the alternative to conventional chemical launch systems. This paper analytically examines the feasibility of SSTO system powered by RP lasers. The trajectory from the ground to the geosynchronous orbit is computed and the launch cost including laser-base development is estimated. The engine performance is evaluated by CFD computations and a cycle analysis. The results show that the beam power of 2.3MW per unit initial vehicle mass is optimum to reach a geo-synchronous transfer orbit, and 3,000 launches are necessary to redeem the cost for laser transmitter.

Short spatial filters with spherical lenses for high-power pulsed lasers

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

Burdonov, K F; Soloviev, A A; Shaikin, A A

We report possible employment of short spatial filters based on spherical lenses in a pulsed laser source (neodymium glass, 300 J, 1 ns). The influence of the spherical aberration on the quality of output radiation and coefficient of conversion to the second harmonics is studied. The ultra-short aberration spatial filter of length 1.9 m with an aperture of 122 mm is experimentally tested. A considerable shortening of multi-cascade pump lasers for modern petawatt laser systems is demonstrated by the employment of short spatial filters without expensive aspherical optics. (elements of laser systems)

A Fuzzy Logic Based Controller for the Automated Alignment of a Laser-beam-smoothing Spatial Filter

NASA Technical Reports Server (NTRS)

Krasowski, M. J.; Dickens, D. E.

1992-01-01

A fuzzy logic based controller for a laser-beam-smoothing spatial filter is described. It is demonstrated that a human operator's alignment actions can easily be described by a system of fuzzy rules of inference. The final configuration uses inexpensive, off-the-shelf hardware and allows for a compact, readily implemented embedded control system.

Nonlinear dynamics of laser systems with elements of a chaos: Advanced computational code

NASA Astrophysics Data System (ADS)

Buyadzhi, V. V.; Glushkov, A. V.; Khetselius, O. Yu; Kuznetsova, A. A.; Buyadzhi, A. A.; Prepelitsa, G. P.; Ternovsky, V. B.

2017-10-01

A general, uniform chaos-geometric computational approach to analysis, modelling and prediction of the non-linear dynamics of quantum and laser systems (laser and quantum generators system etc) with elements of the deterministic chaos is briefly presented. The approach is based on using the advanced generalized techniques such as the wavelet analysis, multi-fractal formalism, mutual information approach, correlation integral analysis, false nearest neighbour algorithm, the Lyapunov’s exponents analysis, and surrogate data method, prediction models etc There are firstly presented the numerical data on the topological and dynamical invariants (in particular, the correlation, embedding, Kaplan-York dimensions, the Lyapunov’s exponents, Kolmogorov’s entropy and other parameters) for laser system (the semiconductor GaAs/GaAlAs laser with a retarded feedback) dynamics in a chaotic and hyperchaotic regimes.

Large laser projection displays utilizing all-solid-state RGB lasers

NASA Astrophysics Data System (ADS)

Xu, Zuyan; Bi, Yong

2005-01-01

RGB lasers projection displays have the advantages of producing large color triangle, high color saturation and high image resolution. In this report, with more than 4W white light synthesized by red (671nm), green (532nm) and blue (473nm) lasers, a RGB laser projection display system based on diode pumped solid-state lasers is developed and the performance of brilliant and vivid DVD dynamitic pictures on 60 inch screen is demonstrated.

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

Graphene devices based on laser scribing technology

NASA Astrophysics Data System (ADS)

Qiao, Yan-Cong; Wei, Yu-Hong; Pang, Yu; Li, Yu-Xing; Wang, Dan-Yang; Li, Yu-Tao; Deng, Ning-Qin; Wang, Xue-Feng; Zhang, Hai-Nan; Wang, Qian; Yang, Zhen; Tao, Lu-Qi; Tian, He; Yang, Yi; Ren, Tian-Ling

2018-04-01

Graphene with excellent electronic, thermal, optical, and mechanical properties has great potential applications. The current devices based on graphene grown by micromechanical exfoliation, chemical vapor deposition (CVD), and thermal decomposition of silicon carbide are still expensive and inefficient. Laser scribing technology, a low-cost and time-efficient method of fabricating graphene, is introduced in this review. The patterning of graphene can be directly performed on solid and flexible substrates. Therefore, many novel devices such as strain sensors, acoustic devices, memory devices based on laser scribing graphene are fabricated. The outlook and challenges of laser scribing technology have also been discussed. Laser scribing may be a potential way of fabricating wearable and integrated graphene systems in the future.

Measurement and compensation schemes for the pulse front distortion of ultra-intensity ultra-short laser pulses

NASA Astrophysics Data System (ADS)

Wu, Fenxiang; Xu, Yi; Yu, Linpeng; Yang, Xiaojun; Li, Wenkai; Lu, Jun; Leng, Yuxin

2016-11-01

Pulse front distortion (PFD) is mainly induced by the chromatic aberration in femtosecond high-peak power laser systems, and it can temporally distort the pulse in the focus and therefore decrease the peak intensity. A novel measurement scheme is proposed to directly measure the PFD of ultra-intensity ultra-short laser pulses, which can work not only without any extra struggle for the desired reference pulse, but also largely reduce the size of the required optical elements in measurement. The measured PFD in an experimental 200TW/27fs laser system is in good agreement with the calculated result, which demonstrates the validity and feasibility of this method effectively. In addition, a simple compensation scheme based on the combination of concave lens and parabolic lens is also designed and proposed to correct the PFD. Based on the theoretical calculation, the PFD of above experimental laser system can almost be completely corrected by using this compensator with proper parameters.

Base-Level Management of Laser Radiation Protection Program

DTIC Science & Technology

1992-02-01

safety eyewear . special considerations for medical lasers and optical fibers, and summary evaluations of common Air Force laser systems... optical density of 2. Laser safety eyewear should have the optical density clearly marked for ail wavelengths for which the eyewear provides protection. c...density of protective eyewear . The optical density required for laser safety eyewear is dependent on the irradiance or radiant exposure-of the

All-Fiber Configuration Laser Self-Mixing Doppler Velocimeter Based on Distributed Feedback Fiber Laser.

PubMed

Wu, Shuang; Wang, Dehui; Xiang, Rong; Zhou, Junfeng; Ma, Yangcheng; Gui, Huaqiao; Liu, Jianguo; Wang, Huanqin; Lu, Liang; Yu, Benli

2016-07-27

In this paper, a novel velocimeter based on laser self-mixing Doppler technology has been developed for speed measurement. The laser employed in our experiment is a distributed feedback (DFB) fiber laser, which is an all-fiber structure using only one Fiber Bragg Grating to realize optical feedback and wavelength selection. Self-mixing interference for optical velocity sensing is experimentally investigated in this novel system, and the experimental results show that the Doppler frequency is linearly proportional to the velocity of a moving target, which agrees with the theoretical analysis commendably. In our experimental system, the velocity measurement can be achieved in the range of 3.58 mm/s-2216 mm/s with a relative error under one percent, demonstrating that our novel all-fiber configuration velocimeter can implement wide-range velocity measurements with high accuracy.

A simple and highly sensitive spectroscopic fluorescence-detection system for multi-channel plastic-microchip electrophoresis based on side-entry laser-beam zigzag irradiation.

PubMed

Anazawa, Takashi; Uchiho, Yuichi; Yokoi, Takahide; Chalkidis, George; Yamazaki, Motohiro

2017-06-27

A five-color fluorescence-detection system for eight-channel plastic-microchip electrophoresis was developed. In the eight channels (with effective electrophoretic lengths of 10 cm), single-stranded DNA fragments were separated (with single-base resolution up to 300 bases within 10 min), and seventeen-loci STR genotyping for forensic human identification was successfully demonstrated. In the system, a side-entry laser beam is passed through the eight channels (eight A channels), with alternately arrayed seven sacrificial channels (seven B channels), by a technique called "side-entry laser-beam zigzag irradiation." Laser-induced fluorescence from the eight A channels and Raman-scattered light from the seven B channels are then simultaneously, uniformly, and spectroscopically detected, in the direction perpendicular to the channel array plane, through a transmission grating and a CCD camera. The system is therefore simple and highly sensitive. Because the microchip is fabricated by plastic-injection molding, it is inexpensive and disposable and thus suitable for actual use in various fields.

A fast high-precision six-degree-of-freedom relative position sensor

NASA Astrophysics Data System (ADS)

Hughes, Gary B.; Macasaet, Van P.; Griswold, Janelle; Sison, Claudia A.; Lubin, Philip; Meinhold, Peter; Suen, Jonathan; Brashears, Travis; Zhang, Qicheng; Madajian, Jonathan

2016-03-01

Lasers are commonly used in high-precision measurement and profiling systems. Some laser measurement systems are based on interferometry principles, and others are based on active triangulation, depending on requirements of the application. This paper describes an active triangulation laser measurement system for a specific application wherein the relative position of two fixed, rigid mechanical components is to be measured dynamically with high precision in six degrees of freedom (DOF). Potential applications include optical systems with feedback to control for mechanical vibration, such as target acquisition devices with multiple focal planes. The method uses an array of several laser emitters mounted on one component. The lasers are directed at a reflective surface on the second component. The reflective surface consists of a piecewise-planar pattern such as a pyramid, or more generally a curved reflective surface such as a hyperbolic paraboloid. The reflected spots are sensed at 2-dimensional photodiode arrays on the emitter component. Changes in the relative position of the emitter component and reflective surface will shift the location of the reflected spots within photodiode arrays. Relative motion in any degree of freedom produces independent shifts in the reflected spot locations, allowing full six-DOF relative position determination between the two component positions. Response time of the sensor is limited by the read-out rate of the photodiode arrays. Algorithms are given for position determination with limits on uncertainty and sensitivity, based on laser and spot-sensor characteristics, and assuming regular surfaces. Additional uncertainty analysis is achievable for surface irregularities based on calibration data.

Modeling of photoluminescence in laser-based lighting systems

NASA Astrophysics Data System (ADS)

Chatzizyrli, Elisavet; Tinne, Nadine; Lachmayer, Roland; Neumann, Jörg; Kracht, Dietmar

2017-12-01

The development of laser-based lighting systems has been the latest step towards a revolution in illumination technology brought about by solid-state lighting. Laser-activated remote phosphor systems produce white light sources with significantly higher luminance than LEDs. The weak point of such systems is often considered to be the conversion element. The high-intensity exciting laser beam in combination with the limited thermal conductivity of ceramic phosphor materials leads to thermal quenching, the phenomenon in which the emission efficiency decreases as temperature rises. For this reason, the aim of the presented study is the modeling of remote phosphor systems in order to investigate their thermal limitations and to calculate the parameters for optimizing the efficiency of such systems. The common approach to simulate remote phosphor systems utilizes a combination of different tools such as ray tracing algorithms and wave optics tools for describing the incident and converted light, whereas the modeling of the conversion process itself, i.e. photoluminescence, in most cases is circumvented by using the absorption and emission spectra of the phosphor material. In this study, we describe the processes involved in luminescence quantum-mechanically using the single-configurational-coordinate diagram as well as the Franck-Condon principle and propose a simulation model that incorporates the temperature dependence of these processes. Following an increasing awareness of climate change and environmental issues, the development of ecologically friendly lighting systems featuring low power consumption and high luminous efficiency is imperative more than ever. The better understanding of laser-based lighting systems is an important step towards that aim as they may improve on LEDs in the near future.

A compact and low-cost laser induced fluorescence detector with silicon based photodetector assembly for capillary flow systems.

PubMed

Geng, Xuhui; Shi, Meng; Ning, Haijing; Feng, Chunbo; Guan, Yafeng

2018-05-15

A compact and low-cost laser induced fluorescence (LIF) detector based on confocal structure for capillary flow systems was developed and applied for analysis of Her2 protein on single Hela cells. A low-power and low-cost 450 nm laser diode (LD) instead of a high quality laser was used as excitation light source. A compact optical design together with shortened optical path length improved the optical efficiency and detection sensitivity. A superior silicon based photodetector assembly was used for fluorescence detection instead of a photomultiplier (PMT). The limit of detection (LOD) for fluorescein sodium was 3 × 10 -12 M or 165 fluorescein molecules in detection volume measured on a homemade capillary electroosmotic driven (EOD)-LIF system, which was similar to commercial LIFs. Compared to commercial LIFs, the whole volume of our LIF was reduced to 1/2-1/3, and the cost was less than 1/3 of them. Copyright © 2018 Elsevier B.V. All rights reserved.

A study on new method of noninvasive esophageal venous pressure measurement based on the airflow and laser detection technology.

PubMed

Hu, Chenghuan; Huang, Feizhou; Zhang, Rui; Zhu, Shaihong; Nie, Wanpin; Liu, Xunyang; Liu, Yinglong; Li, Peng

2015-01-01

Using optics combined with automatic control and computer real-time image detection technology, a novel noninvasive method of noncontact pressure manometry was developed based on the airflow and laser detection technology in this study. The new esophageal venous pressure measurement system was tested in-vitro experiments. A stable and adjustable pulse stream was produced from a self-developed pump and a laser emitting apparatus could generate optical signals which can be captured by image acquisition and analysis system program. A synchronization system simultaneous measured the changes of air pressure and the deformation of the vein wall to capture the vascular deformation while simultaneously record the current pressure value. The results of this study indicated that the pressure values tested by the new method have good correlation with the actual pressure value in animal experiments. The new method of noninvasive pressure measurement based on the airflow and laser detection technology is accurate, feasible, repeatable and has a good application prospects.

Characterization of a FBG sensor interrogation system based on a mode-locked laser scheme.

PubMed

Madrigal, Javier; Fraile-Peláez, Francisco Javier; Zheng, Di; Barrera, David; Sales, Salvador

2017-10-02

This paper is focused on the characterization of a fiber Bragg grating (FBG) sensor interrogation system based on a fiber ring laser with a semiconductor optical amplifier as the gain medium, and an in-loop electro-optical modulator. This system operates as a switchable active (pulsed) mode-locked laser. The operation principle of the system is explained theoretically and validated experimentally. The ability of the system to interrogate an array of different FBGs in wavelength and spatial domain is demonstrated. Simultaneously, the influence of several important parameters on the performance of the interrogation technique has been investigated. Specifically, the effects of the bandwidth and the reflectivity of the FBGs, the SOA gain, and the depth of the intensity modulation have been addressed.

Project Dragonfly: A feasibility study of interstellar travel using laser-powered light sail propulsion

NASA Astrophysics Data System (ADS)

Perakis, Nikolaos; Schrenk, Lukas E.; Gutsmiedl, Johannes; Koop, Artur; Losekamm, Martin J.

2016-12-01

Light sail-based propulsion systems are a candidate technology for interplanetary and interstellar missions due to their flexibility and the fact that no fuel has to be carried along. In 2014, the Initiative for Interstellar Studies (i4is) hosted the Project Dragonfly Design Competition, which aimed at assessing the feasibility of sending an interstellar probe propelled by a laser-powered light sail to another star system. We analyzed and designed a mission to the Alpha Centauri system, with the objective to carry out science operations at the destination. Based on a comprehensive evaluation of currently available technologies and possible locations, we selected a lunar architecture for the laser system. It combines the advantages of surface- and space-based systems, as it requires no station keeping and suffers no atmospheric losses. We chose a graphene-based sandwich material for the light sail because of its low density. Deceleration of the spacecraft sufficient for science operations at the target system is achieved using both magnetic and electric sails. Applying these assumptions in a simulation leads to the conclusion that 250 kg of scientific payload can be sent to Alpha Centauri within the Project Dragonfly Design Competition's constraints of 100 year travel duration and 100 GW laser beam power. This is only sufficient to fulfill parts of the identified scientific objectives, and therefore renders the usefulness of such a mission questionable. A better sail material or higher laser power would improve the acceleration behavior, an increase in the mission time would allow for larger spacecraft masses.

Progress in Cherenkov femtosecond fiber lasers

PubMed Central

Liu, Xiaomin; Svane, Ask S.; Lægsgaard, Jesper; Tu, Haohua; Boppart, Stephen A.; Turchinovich, Dmitry

2016-01-01

We review the recent developments in the field of ultrafast Cherenkov fiber lasers. Two essential properties of such laser systems – broad wavelength tunability and high efficiency of Cherenkov radiation wavelength conversion are discussed. The exceptional performance of the Cherenkov fiber laser systems are highlighted - dependent on the realization scheme, the Cherenkov lasers can generate the femtosecond output tunable across the entire visible and even the UV range, and for certain designs more than 40 % conversion efficiency from the pump to Cherenkov signal can be achieved. The femtosecond Cherenkov laser with all-fiber architecture is presented and discussed. Operating in the visible range, it delivers 100–200 fs wavelength-tunable pulses with multimilliwatt output power and exceptionally low noise figure an order of magnitude lower than the traditional wavelength tunable supercontinuum-based femtosecond sources. The applications for Cherenkov laser systems in practical biophotonics and biomedical applications, such as bio-imaging and microscopy, are discussed. PMID:27110037

Progress in Cherenkov femtosecond fiber lasers.

PubMed

Liu, Xiaomin; Svane, Ask S; Lægsgaard, Jesper; Tu, Haohua; Boppart, Stephen A; Turchinovich, Dmitry

2016-01-20

We review the recent developments in the field of ultrafast Cherenkov fiber lasers. Two essential properties of such laser systems - broad wavelength tunability and high efficiency of Cherenkov radiation wavelength conversion are discussed. The exceptional performance of the Cherenkov fiber laser systems are highlighted - dependent on the realization scheme, the Cherenkov lasers can generate the femtosecond output tunable across the entire visible and even the UV range, and for certain designs more than 40 % conversion efficiency from the pump to Cherenkov signal can be achieved. The femtosecond Cherenkov laser with all-fiber architecture is presented and discussed. Operating in the visible range, it delivers 100-200 fs wavelength-tunable pulses with multimilliwatt output power and exceptionally low noise figure an order of magnitude lower than the traditional wavelength tunable supercontinuum-based femtosecond sources. The applications for Cherenkov laser systems in practical biophotonics and biomedical applications, such as bio-imaging and microscopy, are discussed.

Laser system for testing radiation imaging detector circuits

NASA Astrophysics Data System (ADS)

Zubrzycka, Weronika; Kasinski, Krzysztof

2015-09-01

Performance and functionality of radiation imaging detector circuits in charge and position measurement systems need to meet tight requirements. It is therefore necessary to thoroughly test sensors as well as read-out electronics. The major disadvantages of using radioactive sources or particle beams for testing are high financial expenses and limited accessibility. As an alternative short pulses of well-focused laser beam are often used for preliminary tests. There are number of laser-based devices available on the market, but very often their applicability in this field is limited. This paper describes concept, design and validation of laser system for testing silicon sensor based radiation imaging detector circuits. The emphasis is put on keeping overall costs low while achieving all required goals: mobility, flexible parameters, remote control and possibility of carrying out automated tests. The main part of the developed device is an optical pick-up unit (OPU) used in optical disc drives. The hardware includes FPGA-controlled circuits for laser positioning in 2 dimensions (horizontal and vertical), precision timing (frequency and number) and amplitude (diode current) of short ns-scale (3.2 ns) light pulses. The system is controlled via USB interface by a dedicated LabVIEW-based application enabling full manual or semi-automated test procedures.

A laser-based vision system for weld quality inspection.

PubMed

Huang, Wei; Kovacevic, Radovan

2011-01-01

Welding is a very complex process in which the final weld quality can be affected by many process parameters. In order to inspect the weld quality and detect the presence of various weld defects, different methods and systems are studied and developed. In this paper, a laser-based vision system is developed for non-destructive weld quality inspection. The vision sensor is designed based on the principle of laser triangulation. By processing the images acquired from the vision sensor, the geometrical features of the weld can be obtained. Through the visual analysis of the acquired 3D profiles of the weld, the presences as well as the positions and sizes of the weld defects can be accurately identified and therefore, the non-destructive weld quality inspection can be achieved.

A Laser-Based Vision System for Weld Quality Inspection

PubMed Central

Huang, Wei; Kovacevic, Radovan

2011-01-01

Welding is a very complex process in which the final weld quality can be affected by many process parameters. In order to inspect the weld quality and detect the presence of various weld defects, different methods and systems are studied and developed. In this paper, a laser-based vision system is developed for non-destructive weld quality inspection. The vision sensor is designed based on the principle of laser triangulation. By processing the images acquired from the vision sensor, the geometrical features of the weld can be obtained. Through the visual analysis of the acquired 3D profiles of the weld, the presences as well as the positions and sizes of the weld defects can be accurately identified and therefore, the non-destructive weld quality inspection can be achieved. PMID:22344308

Wavelength-tunable, passively mode-locked fiber laser based on graphene and chirped fiber Bragg grating.

PubMed

He, Xiaoying; Liu, Zhi-bo; Wang, D N

2012-06-15

We demonstrate a wavelength-tunable, passively mode-locked erbium-doped fiber laser based on graphene and chirped fiber Bragg grating. The saturable absorber used to enable passive mode-locking in the fiber laser is a section of microfiber covered by graphene film, which allows light-graphene interaction via the evanescent field of the microfiber. The wavelength of the laser can be continuously tuned by adjusting the chirped fiber Bragg grating, while maintaining mode-locking stability. Such a system has high potential in tuning the mode-locked laser pulses across a wide wavelength range.

Intensity noise properties of a compact laser device based on a miniaturized MOPA system for spectroscopic applications

NASA Astrophysics Data System (ADS)

Baumgärtner, S.; Juhl, S.; Opalevs, D.; Sahm, A.; Hofmann, J.; Leisching, P.; Paschke, K.

2018-02-01

We present a novel compact laser device based on a semiconductor master-oscillator power-amplifier (MOPA) emitting at 772 nm, suitable for quantum optic and spectroscopy. The optical performance of the laser device is characterized. For miniaturized lasers the thermal management is challenging, we therefore perform thermal simulations and measurements. The first demonstrator is emitting more than 3 W optical power with a linewidth below 2lMHz. Using this MOPA design also compact devices for quantum optics (e.g. rubidium atomic clock) and seed lasers for frequency conversion can be realized [1].

Stabilized diode seed laser for flight and space-based remote lidar sensing applications

NASA Astrophysics Data System (ADS)

McNeil, Shirley; Pandit, Pushkar; Battle, Philip; Rudd, Joe; Hovis, Floyd

2017-08-01

AdvR, through support of the NASA SBIR program, has developed fiber-based components and sub-systems that are routinely used on NASA's airborne missions, and is now developing an environmentally hardened, diode-based, locked wavelength, seed laser for future space-based high spectral resolution lidar applications. The seed laser source utilizes a fiber-coupled diode laser, a fiber-coupled, calibrated iodine reference module to provide an absolute wavelength reference, and an integrated, dual-element, nonlinear optical waveguide component for second harmonic generation, spectral formatting and wavelength locking. The diode laser operates over a range close to 1064.5 nm, provides for stabilization of the seed to the desired iodine transition and allows for a highly-efficient, fully-integrated seed source that is well-suited for use in airborne and space-based environments. A summary of component level environmental testing and spectral purity measurements with a seeded Nd:YAG laser will be presented. A direct-diode, wavelength-locked seed laser will reduce the overall size weight and power (SWaP) requirements of the laser transmitter, thus directly addressing the need for developing compact, efficient, lidar component technologies for use in airborne and space-based environments.

Space-Based Lidar Systems

NASA Technical Reports Server (NTRS)

Sun, Xiaoli

2012-01-01

An overview of space-based lidar systems is presented. from the first laser altimeter on APOLLO 15 mission in 1971 to the Mercury Laser Altimeter on MESSENGER mission currently in orbit, and those currently under development. Lidar, which stands for Light Detection And Ranging, is a powerful tool in remote sensing from space. Compared to radars, lidars operate at a much shorter wavelength with a much narrower beam and much smaller transmitter and receiver. Compared to passive remote sensing instruments. lidars carry their own light sources and can continue measuring day and night. and over polar regions. There are mainly two types of lidars depending on the types of measurements. lidars that are designed to measure the distance and properties of hard targets are often called laser rangers or laser altimeters. They are used to obtain the surface elevation and global shape of a planet from the laser pulse time-of-night and the spacecraft orbit position. lidars that are designed to measure the backscattering and absorption of a volume scatter, such as clouds and aerosols, are often just called lidars and categorized by their measurements. such as cloud and aerosol lidar, wind lidar, CO2 lidar, and so on. The advantages of space-based lidar systems over ground based lidars are the abilities of global coverage and continuous measurements.

NGSLR Safety Handbook

NASA Technical Reports Server (NTRS)

McGarry, Jan

2015-01-01

NASA's Next Generation Satellite Laser Ranging (NGSLR) station is the prototype for NASA's Satellite Laser Ranging (SLR) systems which will be deployed around the world in the coming decade. The NGSLR system will be an autonomous, photon-counting SLR station with an expected absolute range accuracy of better than one centimeter and a normal point (time-averaged) range precision better than one millimeter. The system provides continuous (weather permitting), 24 hour tracking coverage to an existing constellation of approximately two dozen artificial satellites equipped with passive retroreflector arrays, using pulsed, 532 nm, class IV laser systems. Current details on the approved laser systems can be found in the Appendix 1 of this document. This safety plan addresses the potential hazards to emitted laser radiation, which can occur both inside and outside the shelter. Hazards within the shelter are mitigated through posted warning signs, activated warning lights, procedural controls, personal protective equipment (PPE), laser curtains, beam blocking systems, interlock controls, pre-configured laser control settings, and other controls discussed in this document. Since the NGSLR is a satellite tracking system, laser hazards exist outside the shelter to personnel on the shelter roof and to passing aircraft. Potential exposure to personnel outside the system is mitigated through the use of posted warning signs, access control, procedural controls, a stairwell interlock, beam attenuation/blocking devices, and a radar based aircraft detection system.

Optical frequency stabilization in infrared region using improved dual feed-back loop

NASA Astrophysics Data System (ADS)

Ružička, B.; Číp, O.; Lazar, J.

2007-03-01

Modern technologies such as DWDM (Dense Wavelength Division Multiplex) need precise stability of laser frequencies. According to this fact, requirements of new etalons of optical frequencies in the telecommunication band is rapidly growing. Lasers working in near infrared telecommunication band (1500-1600 nm) can be stabilized to 12C IIH II or 13C IIH II (acetylene) gas absorption lines. The acetylene gas absorption has been widely studied and accepted by international bodies of standardization as a primary wavelength reference in the near infrared band around 1550 nm. Our aim was to design and develop a compact fibre optics laser system generating coherent light in near-IR band with high frequency stability (at least 1.10 -8). This system should become a base for realization of a primary frequency standard for optical communications in the Czech Republic. Such an etalon will be needed for calibration of wavelengthmeters and spectral analysers for DWDM communication systems. We are co-operating with CMI (Czech Metrology Institute) on this project. We present stabilized laser system based on a single frequency DFB (Distributed Feedback) laser diode with a narrow spectral profile. The laser is pre-stabilized by means of the FM-spectroscopy on a passive resonator. Thanks to a fast feed-back loop we are able to improve spectral characteristics of the laser. The laser frequency is locked by a relatively slow second feed-back loop on an absorption line of acetylene vapour which is sealed in a cell under the optimised pressure.

Near-IR laser frequency standard stabilized using FM-spectroscopy

NASA Astrophysics Data System (ADS)

Ružička, Bohdan; Číp, Ondřej; Lazar, Josef

2006-02-01

At the present time fiber-optics and optical communication are in rapid progress. Modern technologies such as DWDM (Dense Wavelength Division Multiplex) need precise stability of laser frequencies. According to this fact, requirements of new etalons of optical frequencies in the telecommunication band is rapidly growing. Lasers working in near infrared telecommunication band (1500-1600 nm) can be stabilized to 12C IIH II or 13C IIH II (acetylene) gas absorption lines. The acetylene gas absorption has been widely studied and accepted by international bodies of standardization as a primary wavelength reference in the near infrared band around 1550nm. Our aim was to design and develop a compact fibre optics laser system generating coherent light in near-JR band with high frequency stability (at least 1.10 -8). This system should become a base for realization of a primary frequency standard for optical communications in the Czech Republic. Such an etalon will be needed for calibration of wavelength-meters and spectral analysers for DWDM communication systems. We are co-operating with CMI (Czech Metrology Institute) on this project. We present stabilized laser system based on a single frequency DFB (Distributed Feedback) laser diode with a narrow spectral profile. The laser is pre-stabilized by means of the FM-spectroscopy on a passive resonator. Thanks to a fast feed-back loop we are able to improve spectral characteristics of the laser. The laser frequency is locked by a relatively slow second feed-back loop on an absorption line of acetylene vapour which is sealed in a cell under the optimised pressure.

Use of a novel tunable solid state disk laser as a diagnostic system for laser-induced fluorescence

NASA Astrophysics Data System (ADS)

Paa, Wolfgang; Triebel, Wolfgang

2004-09-01

An all solid state disk laser system-named "Advanced Disk Laser (ADL)" -particularly tailored for laser induced fluorescence (LIF) in combustion processes is presented. The system currently under development comprises an Yb:YAG-seedlaser and a regenerative amplifier. Both are based on the disk laser concept as a new laser architecture. This allows a tunable, compact, efficient diode pumped solid state laser (DPSSL) system with repetition rates in the kHz region. After frequency conversion to the UV-spectral region via third and fourth harmonics generation, this laser-due to its unique properties such as single-frequency operation, wavelength tuneability and excellent beam profile-is well suited for excitation of small molecules such as formaldehyde, OH, NO or O2, which are characteristic for combustion processes. Using the method of planar laser induced fluorescence (PLIF) we observed concentration distributions of formaldehyde in cool and hot flames of a specially designed diethyl-ether burner. The images recorded with 1 kHz repetition rate allow visualizing the distribution of formaldehyde on a 1 ms time scale. This demonstrates for the first time the usability of this novel laser for LIF measurements and is the first step towards integration of the ADL into capsules for drop towers and the international space station.

Laparoscopic laser soldering for repair of ureteropelvic junction obstruction in the porcine model.

PubMed

Shumalinsky, Dmitry; Lobik, Leonid; Cytron, Shmuel; Halpern, Marisa; Vasilyev, Tamar; Ravid, Avi; Katzir, Abraham

2004-03-01

Laparoscopic pyeloplasty is used for the repair of ureteropelvic junction (UPJ) obstruction. Our objective was to introduce laser soldering to this procedure. We developed a system based on a CO2 laser, an infrared detector, and two infrared transmitting optical fibers to obtain temperature-controlled laser soldering of cuts in tissues. The system was used for laparoscopic soldering of incisions in the kidneys of pigs. We carried out laparoscopic pyeloplasty successfully in a porcine model using fiberoptic laser soldering. Laparoscopic laser soldering was found to be faster than suturing. It was easier to use and provided watertight bonding. This technique will be useful in pyeloplasty as well as other laparoscopic surgical procedures.

An automated inner dimensional measurement system based on a laser displacement sensor for long-stepped pipes.

PubMed

Zhang, Fumin; Qu, Xinghua; Ouyang, Jianfei

2012-01-01

A novel measurement prototype based on a mobile vehicle that carries a laser scanning sensor is proposed. The prototype is intended for the automated measurement of the interior 3D geometry of large-diameter long-stepped pipes. The laser displacement sensor, which has a small measurement range, is mounted on an extended arm of known length. It is scanned to improve the measurement accuracy for large-sized pipes. A fixing mechanism based on two sections is designed to ensure that the stepped pipe is concentric with the axis of rotation of the system. Data are acquired in a cylindrical coordinate system and fitted in a circle to determine diameter. Systematic errors covering arm length, tilt, and offset errors are analyzed and calibrated. The proposed system is applied to sample parts and the results are discussed to verify its effectiveness. This technique measures a diameter of 600 mm with an uncertainty of 0.02 mm at a 95% confidence probability. A repeatability test is performed to examine precision, which is 1.1 μm. A laser tracker is used to verify the measurement accuracy of the system, which is evaluated as 9 μm within a diameter of 600 mm.

SU-E-J-32: Calypso(R) and Laser-Based Localization Systems Comparison for Left-Sided Breast Cancer Patients Using Deep Inspiration Breath Hold

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

Robertson, S; Kaurin, D; Sweeney, L

2014-06-01

Purpose: Our institution uses a manual laser-based system for primary localization and verification during radiation treatment of left-sided breast cancer patients using deep inspiration breath hold (DIBH). This primary system was compared with sternum-placed Calypso(R) beacons (Varian Medical Systems, CA). Only intact breast patients are considered for this analysis. Methods: During computed tomography (CT) simulation, patients have BB and Calypso(R) surface beacons positioned sternally and marked for free-breathing and DIBH CTs. During dosimetry planning, BB longitudinal displacement between free breathing and DIBH CT determines laser mark (BH mark) location. Calypso(R) beacon locations from the DIBH CT are entered at themore » Tracking Station. During Linac simulation and treatment, patients inhale until the cross-hair and/or lasers coincide with the BH Mark, which can be seen using our high quality cameras (Pelco, CA). Daily Calypso(R) displacement values (difference from the DIBH-CT-based plan) are recorded.The displacement mean and standard deviation was calculated for each patient (77 patients, 1845 sessions). An aggregate mean and standard deviation was calculated weighted by the number of patient fractions.Some patients were shifted based on MV ports. A second data set was calculated with Calypso(R) values corrected by these shifts. Results: Mean displacement values indicate agreement within 1±3mm, with improvement for shifted data (Table). Conclusion: Both unshifted and shifted data sets show the Calypso(R) system coincides with the laser system within 1±3mm, demonstrating either localization/verification system will Resultin similar clinical outcomes. Displacement value uncertainty unilaterally reduces when shifts are taken into account.« less

Infrared laser spectroscopic trace gas sensing

NASA Astrophysics Data System (ADS)

Sigrist, Markus

2016-04-01

Chemical sensing and analyses of gas samples by laser spectroscopic methods are attractive owing to several advantages such as high sensitivity and specificity, large dynamic range, multi-component capability, and lack of pretreatment or preconcentration procedures. The preferred wavelength range comprises the fundamental molecular absorption range in the mid-infared between 3 and 15 μm, whereas the near-infrared range covers the (10-100 times weaker) higher harmonics and combination bands. The availability of near-infrared and, particularly, of broadly tunable mid-infrared sources like external cavity quantum cascade lasers (EC-QCLs), interband cascade lasers (ICLs), difference frequency generation (DFG), optical parametric oscillators (OPOs), recent developments of diode-pumped lead salt semiconductor lasers, of supercontinuum sources or of frequency combs have eased the implementation of laser-based sensing devices. Sensitive techniques for molecular absorption measurements include multipass absorption, various configurations of cavity-enhanced techniques such as cavity ringdown (CRD), or of photoacoustic spectroscopy (PAS) including quartz-enhanced (QEPAS) or cantilever-enhanced (CEPAS) techniques. The application requirements finally determine the optimum selection of laser source and detection scheme. In this tutorial talk I shall discuss the basic principles, present various experimental setups and illustrate the performance of selected systems for chemical sensing of selected key atmospheric species. Applications include an early example of continuous vehicle emission measurements with a mobile CO2-laser PAS system [1]. The fast analysis of C1-C4 alkanes at sub-ppm concentrations in gas mixtures is of great interest for the petrochemical industry and was recently achieved with a new type of mid-infrared diode-pumped piezoelectrically tuned lead salt vertical external cavity surface emitting laser (VECSEL) [2]. Another example concerns measurements on short-lived species like nitrous acid (HONO) with a QCL-based QEPAS system where the small gas sampling volume and hence short gas residence time are of particular importance [3]. A true analysis of gas mixtures has been performed with a widely tunable DFG system in a medical application that could also be adapted to atmospheric species [4]. It is demonstrated that a laser-based narrowband system with broad tunability combined with an appropriate detection scheme is feasible for the chemical analysis of multi-component gas mixtures even with an a priori unknown composition. Most recent examples will further confirm the great potential of infrared laser-based devices for trace species sensing. References 1. D. Marinov and M.W. Sigrist: "Monitoring of road-traffic emission with mobile photoacoustic system", Photochem. and Photobiol. Sciences 2, 774-778 (2003) 2. J.M. Rey, M. Fill, F. Felder and M.W. Sigrist: "Broadly tunable mid-infrared VECSEL for multiple components hydrocarbons gas sensing", Appl. Phys. B 117, 935-939 (2014) 3. H. Yi, R. Maamary, X. Gao, M.W. Sigrist, E. Fertein, and W. Chen: "Short-lived species detection of nitrous acid by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy", Appl. Phys. Lett. 106, 101109 (2015) 4. M. Gianella and M.W. Sigrist: "Chemical Analysis of Surgical Smoke by Infrared Laser Spectroscopy", Appl. Phys. B 109, 485-496 (2012)

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

Mid-infrared gas absorption sensor based on a broadband external cavity quantum cascade laser

NASA Astrophysics Data System (ADS)

Sun, Juan; Deng, Hao; Liu, Ningwu; Wang, Hongliang; Yu, Benli; Li, Jingsong

2016-12-01

We developed a laser absorption sensor based on a pulsed, broadband tunable external cavity quantum cascade laser (ECQCL) centered at 1285 cm-1. Unlike traditional infrared spectroscopy system, a quartz crystal tuning fork (QCTF) as a light detector was used for laser signal detection. Fast Fourier transform was applied to extract vibration intensity information of QCTF. The sensor system is successfully tested on nitrous oxide (N2O) spectroscopy measurements and compared with a standard infrared detector. The wide wavelength tunability of ECQCL will allow us to access the fundamental vibrational bands of many chemical agents, which are well-suited for trace explosive, chemical warfare agent, and toxic industrial chemical detection and spectroscopic analysis.

Mid-infrared gas absorption sensor based on a broadband external cavity quantum cascade laser.

PubMed

Sun, Juan; Deng, Hao; Liu, Ningwu; Wang, Hongliang; Yu, Benli; Li, Jingsong

2016-12-01

We developed a laser absorption sensor based on a pulsed, broadband tunable external cavity quantum cascade laser (ECQCL) centered at 1285 cm -1 . Unlike traditional infrared spectroscopy system, a quartz crystal tuning fork (QCTF) as a light detector was used for laser signal detection. Fast Fourier transform was applied to extract vibration intensity information of QCTF. The sensor system is successfully tested on nitrous oxide (N 2 O) spectroscopy measurements and compared with a standard infrared detector. The wide wavelength tunability of ECQCL will allow us to access the fundamental vibrational bands of many chemical agents, which are well-suited for trace explosive, chemical warfare agent, and toxic industrial chemical detection and spectroscopic analysis.

Consistency analysis on laser signal in laser guided weapon simulation

NASA Astrophysics Data System (ADS)

Yin, Ruiguang; Zhang, Wenpan; Guo, Hao; Gan, Lin

2015-10-01

The hardware-in-the-loop simulation is widely used in laser semi-active guidance weapon experiments, the authenticity of the laser guidance signal is the key problem of reliability. In order to evaluate the consistency of the laser guidance signal, this paper analyzes the angle of sight, laser energy density, laser spot size, atmospheric back scattering, sun radiation and SNR by comparing the different working state between actual condition and hardware-in-the-loop simulation. Based on measured data, mathematical simulation and optical simulation result, laser guidance signal effects on laser seeker are determined. By using Monte Carlo method, the laser guided weapon trajectory and impact point distribution are obtained, the influence of the systematic error are analyzed. In conclusion it is pointed out that the difference between simulation system and actual system has little influence in normal guidance, has great effect on laser jamming. The research is helpful to design and evaluation of laser guided weapon simulation.

A data processing method based on tracking light spot for the laser differential confocal component parameters measurement system

NASA Astrophysics Data System (ADS)

Shao, Rongjun; Qiu, Lirong; Yang, Jiamiao; Zhao, Weiqian; Zhang, Xin

2013-12-01

We have proposed the component parameters measuring method based on the differential confocal focusing theory. In order to improve the positioning precision of the laser differential confocal component parameters measurement system (LDDCPMS), the paper provides a data processing method based on tracking light spot. To reduce the error caused by the light point moving in collecting the axial intensity signal, the image centroiding algorithm is used to find and track the center of Airy disk of the images collected by the laser differential confocal system. For weakening the influence of higher harmonic noises during the measurement, Gaussian filter is used to process the axial intensity signal. Ultimately the zero point corresponding to the focus of the objective in a differential confocal system is achieved by linear fitting for the differential confocal axial intensity data. Preliminary experiments indicate that the method based on tracking light spot can accurately collect the axial intensity response signal of the virtual pinhole, and improve the anti-interference ability of system. Thus it improves the system positioning accuracy.

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.

Direct carrier-envelope phase control of an amplified laser system.

PubMed

Balčiūnas, Tadas; Flöry, Tobias; Baltuška, Andrius; Stanislauskas, Tomas; Antipenkov, Roman; Varanavičius, Arūnas; Steinmeyer, Günter

2014-03-15

Direct carrier-envelope phase stabilization of an Yb:KGW MOPA laser system is demonstrated with a residual phase jitter reduced to below 100 mrad, which compares favorably with previous stabilization reports, both of amplified laser systems as well as of ytterbium-based oscillators. This novel stabilization scheme relies on a frequency synthesis scheme and a feed-forward approach. The direct stabilization of a sub-MHz frequency comb from a CPA amplifier not only reduces the phase noise but also greatly simplifies the stabilization setup.

Narrow linewidth picosecond UV pulsed laser with mega-watt peak power.

PubMed

Huang, Chunning; Deibele, Craig; Liu, Yun

2013-04-08

We demonstrate a master oscillator power amplifier (MOPA) burst mode laser system that generates 66 ps/402.5 MHz pulses with mega-watt peak power at 355 nm. The seed laser consists of a single frequency fiber laser (linewidth < 5 KHz), a high bandwidth electro-optic modulator (EOM), a picosecond pulse generator, and a fiber based preamplifier. A very high extinction ratio (45 dB) has been achieved by using an adaptive bias control of the EOM. The multi-stage Nd:YAG amplifier system allows a uniformly temporal shaping of the macropulse with a tunable pulse duration. The light output from the amplifier is converted to 355 nm, and over 1 MW peak power is obtained when the laser is operating in a 5-μs/10-Hz macropulse mode. The laser output has a transform-limited spectrum with a very narrow linewidth of individual longitudinal modes. The immediate application of the laser system is the laser-assisted hydrogen ion beam stripping for the Spallation Neutron Source (SNS).

ELI-beamlines: progress in development of next generation short-pulse laser systems

NASA Astrophysics Data System (ADS)

Rus, B.; Bakule, P.; Kramer, D.; Naylon, J.; Thoma, J.; Fibrich, M.; Green, J. T.; Lagron, J. C.; Antipenkov, R.; Bartoníček, J.; Batysta, F.; Baše, R.; Boge, R.; Buck, S.; Cupal, J.; Drouin, M. A.; Durák, M.; Himmel, B.; Havlíček, T.; Homer, P.; Honsa, A.; Horáček, M.; Hríbek, P.; Hubáček, J.; Hubka, Z.; Kalinchenko, G.; Kasl, K.; Indra, L.; Korous, P.; Košelja, M.; Koubíková, L.; Laub, M.; Mazanec, T.; Meadows, A.; Novák, J.; Peceli, D.; Polan, J.; Snopek, D.; Šobr, V.; Trojek, P.; Tykalewicz, B.; Velpula, P.; Verhagen, E.; Vyhlídka, Å.; Weiss, J.; Haefner, C.; Bayramian, A.; Betts, S.; Erlandson, A.; Jarboe, J.; Johnson, G.; Horner, J.; Kim, D.; Koh, E.; Marshall, C.; Mason, D.; Sistrunk, E.; Smith, D.; Spinka, T.; Stanley, J.; Stolz, C.; Suratwala, T.; Telford, S.; Ditmire, T.; Gaul, E.; Donovan, M.; Frederickson, C.; Friedman, G.; Hammond, D.; Hidinger, D.; Chériaux, G.; Jochmann, A.; Kepler, M.; Malato, C.; Martinez, M.; Metzger, T.; Schultze, M.; Mason, P.; Ertel, K.; Lintern, A.; Edwards, C.; Hernandez-Gomez, C.; Collier, J.

2017-05-01

Overview of progress in construction and testing of the laser systems of ELI-Beamlines, accomplished since 2015, is presented. Good progress has been achieved in construction of all four lasers based largely on the technology of diode-pumped solid state lasers (DPSSL). The first part of the L1 laser, designed to provide 200 mJ <15 fs pulses at 1 kHz repetition rate, is up and running. The L2 is a development line employing a 10 J / 10 Hz cryogenic gas-cooled pump laser which has recently been equipped with an advanced cryogenic engine. Operation of the L3-HAPLS system, using a gas-cooled DPSSL pump laser and a Ti:sapphire broadband amplifier, was recently demonstrated at 16 J / 28 fs, at 3.33 Hz rep rate. Finally, the 5 Hz OPCPA front end of the L4 kJ laser is up running and amplification in the Nd:glass large-aperture power amplifiers was demonstrated.

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.

High-power beam combining: a step to a future laser weapon system

NASA Astrophysics Data System (ADS)

Protz, Rudolf; Zoz, Jürgen; Geidek, Franz; Dietrich, Stephan; Fall, Michael

2012-11-01

Due to the enormous progress in the field of high-power fiber lasers during the last years commercial industrial fiber lasers are now available, which deliver a near-diffraction limited beam with power levels up to10kW. For the realization of a future laser weapon system, which can be used for Counter-RAM or similar air defence applications, a laser source with a beam power at the level of 100kW or more is required. At MBDA Germany the concept for a high-energy laser weapon system is investigated, which is based on such existing industrial laser sources as mentioned before. A number of individual high-power fiber laser beams are combined together, using one common beam director telescope. By this "geometric" beam coupling scheme, sufficient laser beam power for an operational laser weapon system can be achieved. The individual beams from the different lasers are steered by servo-loops, using fast tip-tilt mirrors. This principle enables the concentration of the total laser beam power at the common focal point on a distant target, also allowing fine tracking of target movements and first order compensation of turbulence effects on laser beam propagation. The proposed beam combination concept was demonstrated using several experimental set-ups. Different experiments were performed, to investigate laser beam target interaction and target fine tracking also at large distances. Content and results of these investigations are reported. An example for the lay-out of an Air Defence High Energy Laser Weapon (ADHELW ) is given. It can be concluded, that geometric high-power beam combining is an important step for the realization of a laser weapon system in the near future.

NASA Space Laser Technology

NASA Technical Reports Server (NTRS)

Krainak, Michael A.

2015-01-01

Over the next two decades, the number of space based laser missions for mapping, spectroscopy, remote sensing and other scientific investigations will increase several fold. The demand for high wall-plug efficiency, low noise, narrow linewidth laser systems to meet different systems requirements that can reliably operate over the life of a mission will be high. The general trends will be for spatial quality very close to the diffraction limit, improved spectral performance, increased wall-plug efficiency and multi-beam processing. Improved spectral performance will include narrower spectral width (very near the transform limit), increased wavelength stability and or tuning (depending on application) and lasers reaching a wider range of wavelengths stretching into the mid-infrared and the near ultraviolet. We are actively developing high efficiency laser transmitter and high-sensitivity laser receiver systems that are suitable for spaceborne applications.

HiLASE: development of fully diode pumped disk lasers with high average power

NASA Astrophysics Data System (ADS)

Divoky, M.; Smrz, M.; Chyla, M.; Sikocinski, P.; Severova, P.; Novák, O.; Huynh, J.; Nagisetty, S. S.; Miura, T.; Liberatore, C.; Pilař, J.; Slezak, O.; Sawicka, M.; Jambunathan, V.; Gemini, L.; Vanda, J.; Svabek, R.; Endo, A.; Lucianetti, A.; Rostohar, D.; Mason, P. D.; Phillips, P. J.; Ertel, K.; Banerjee, S.; Hernandez-Gomez, C.; Collier, J. L.; Mocek, T.

2015-02-01

An overview of Czech national R&D project HiLASE (High average power pulsed LASEr) is presented. The HiLASE project aims at development of pulsed DPSSL for hi-tech industrial applications. HiLASE will be a user oriented facility with several laser systems with output parameters ranging from a few picosecond pulses with energy of 5 mJ to 0.5 J and repetition rate of 1-100 kHz (based on thin disk technology) to systems with 100 J output energy in nanosecond pulses with repetition rate of 10 Hz (based on multi-slab technology).

Modeling of Adaptive Optics-Based Free-Space Communications Systems

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

Wilks, S C; Morris, J R; Brase, J M

2002-08-06

We introduce a wave-optics based simulation code written for air-optic laser communications links, that includes a detailed model of an adaptive optics compensation system. We present the results obtained by this model, where the phase of a communications laser beam is corrected, after it propagates through a turbulent atmosphere. The phase of the received laser beam is measured using a Shack-Hartmann wavefront sensor, and the correction method utilizes a MEMS mirror. Strehl improvement and amount of power coupled to the receiving fiber for both 1 km horizontal and 28 km slant paths are presented.

Fiber-optic-based laser vapor screen flow visualization system for aerodynamic research in larger scale subsonic and transonic wind tunnels

NASA Technical Reports Server (NTRS)

Erickson, Gary E.; Inenaga, Andrew S.

1994-01-01

Laser vapor screen (LVS) flow visualization systems that are fiber-optic based were developed and installed for aerodynamic research in the Langley 8-Foot Transonic Pressure Tunnel and the Langley 7- by 10-Foot High Speed Tunnel. Fiber optics are used to deliver the laser beam through the plenum shell that surrounds the test section of each facility and to the light-sheet-generating optics positioned in the ceiling window of the test section. Water is injected into the wind tunnel diffuser section to increase the relative humidity and promote condensation of the water vapor in the flow field about the model. The condensed water vapor is then illuminated with an intense sheet of laser light to reveal features of the flow field. The plenum shells are optically sealed; therefore, video-based systems are used to observe and document the flow field. Operational experience shows that the fiber-optic-based systems provide safe, reliable, and high-quality off-surface flow visualization in smaller and larger scale subsonic and transonic wind tunnels. The design, the installation, and the application of the Langley Research Center (LaRC) LVS flow visualization systems in larger scale wind tunnels are highlighted. The efficiency of the fiber optic LVS systems and their insensitivity to wind tunnel vibration, the tunnel operating temperature and pressure variations, and the airborne contaminants are discussed.

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.

Design update and recent results of the Apollon 10 PW facility

NASA Astrophysics Data System (ADS)

Le Garrec, B.; Papadopoulos, D. N.; Le Blanc, C.; Zou, J. P.; Chériaux, G.; Georges, P.; Druon, F.; Martin, L.; Fréneaux, L.; Beluze, A.; Lebas, N.; Mathieu, F.; Audebert, P.

2017-05-01

In this paper we are giving a summary of the Apollon 10 PW facility laser design together with updated laser performance. The Apollon facility is currently under construction in France. The APOLLON laser system is a laser designed for delivering pulses as short as 15 fs (10-15 s) with an energy exceeding 150 Joules on target. The peak power delivered by this laser system will be 10 Petawatts (1016W). The Apollon laser system will be delivering 4 beams: one 10 PW beam (F1 beam 400 mm diameter), one 1 PW beam (F2 beam 140 mm diameter) and two additional probe beams (F3 and F4) at a repetition rate of 1 shot per minute. The laser system is based on Ti-sapphire amplifiers pumped by frequency doubled solid-state lasers. The repetition rate of the high energy part will be 1 shot per minute. The main beam at the output of the last amplifier will be split and dispatched to two experimental areas. The main laser beam is delivering 30 J before compression at a repetition rate of 1 shot per minute and we are currently increasing to get 100J.

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.

Detection system of capillary array electrophoresis microchip based on optical fiber

NASA Astrophysics Data System (ADS)

Yang, Xiaobo; Bai, Haiming; Yan, Weiping

2009-11-01

To meet the demands of the post-genomic era study and the large parallel detections of epidemic diseases and drug screening, the high throughput micro-fluidic detection system is needed urgently. A scanning laser induced fluorescence detection system based on optical fiber has been established by using a green laser diode double-pumped solid-state laser as excitation source. It includes laser induced fluorescence detection subsystem, capillary array electrophoresis micro-chip, channel identification unit and fluorescent signal processing subsystem. V-shaped detecting probe composed with two optical fibers for transmitting the excitation light and detecting induced fluorescence were constructed. Parallel four-channel signal analysis of capillary electrophoresis was performed on this system by using Rhodamine B as the sample. The distinction of different samples and separation of samples were achieved with the constructed detection system. The lowest detected concentration is 1×10-5 mol/L for Rhodamine B. The results show that the detection system possesses some advantages, such as compact structure, better stability and higher sensitivity, which are beneficial to the development of microminiaturization and integration of capillary array electrophoresis chip.

Vibration control for the ARGOS laser launch path

NASA Astrophysics Data System (ADS)

Peter, Diethard; Gässler, Wolfgang; Borelli, Jose; Barl, Lothar; Rabien, S.

2012-07-01

Present and future adaptive optics systems aim for the correction of the atmospheric turbulence over a large field of view combined with large sky coverage. To achieve this goal the telescope is equipped with multiple laser beacons. Still, to measure tip-tilt aberrations a natural guide star is used. For some fields such a tilt-star is not available and a correction on the laser beacons alone is applied. For this method to work well the laser beacons must not be affected by telescope vibrations on their up-link path. For the ARGOS system the jitter of the beacons is specified to be below 0.05. To achieve this goal a vibration compensation system is necessary to mitigate the mechanical disturbances. The ARGOS vibration compensation system is an accelerometer based feed forward system. The accelerometer measurements are fed into a real time controller. To achieve high performance the controller of the system is model based. The output is applied to a fast steering mirror. This paper presents the concept of the ARGOS vibration compensation, the hardware, and laboratory results.

A compact, inexpensive infrared laser system for continuous-wave optical stimulation of the rat prostate cavernous nerves

NASA Astrophysics Data System (ADS)

Perkins, William C.; Lagoda, Gwen A.; Burnett, Arthur L.; Fried, Nathaniel M.

2014-03-01

Optical nerve stimulation (ONS) has been commonly performed in the laboratory using high-power, pulsed, infrared (IR) lasers including Holmium:YAG, diode, and Thulium fiber lasers. However, the relatively high cost of these lasers in comparison with conventional electrical nerve stimulation (ENS) equipment may represent a significant barrier to widespread adoption of ONS. Optical stimulation of the prostate cavernous nerves (CN's) has recently been reported using lower cost, continuous-wave (CW), all-fiber-based diode lasers. This preliminary study describes further miniaturization and cost reduction of the ONS system in the form of a compact, lightweight, cordless, and inexpensive IR laser. A 140-mW, 1560-nm diode laser was integrated with a green aiming beam and delivery optics into a compact ONS system. Surface and subsurface ONS was performed in a total of 5 rats, in vivo, with measurement of an intracavernous pressure (ICP) response during CW laser irradiation for 30 s with a spot diameter of 0.7 mm. Short-term, CW ONS of the prostate CN's is feasible using a compact, inexpensive, batterypowered IR laser diode system. This ONS system may represent an alternative to ENS for laboratory studies, and with further development, a handheld option for ONS in the clinic to identify and preserve the CN's during prostate cancer surgery.

Very-Long-Distance Remote Hearing and Vibrometry

NASA Technical Reports Server (NTRS)

Maleki, Lute; Yu, Nan; Matsko, Andrey; Savchenkov, Anatoliy

2009-01-01

A proposed development of laser-based instrumentation systems would extend the art of laser Doppler vibrometry beyond the prior limits of laser-assisted remote hearing and industrial vibrometry for detecting defects in operating mechanisms. A system according to the proposal could covertly measure vibrations of objects at distances as large as thousands of kilometers and could process the measurement data to enable recognition of vibrations characteristic of specific objects of interest, thereby enabling recognition of the objects themselves. A typical system as envisioned would be placed in orbit around the Earth for use as a means of determining whether certain objects on or under the ground are of interest as potential military targets. Terrestrial versions of these instruments designed for airborne or land- or sea-based operation could be similarly useful for military or law-enforcement purposes. Prior laser-based remote-hearing systems are not capable of either covert operation or detecting signals beyond modest distances when operated at realistic laser power levels. The performances of prior systems for recognition of objects by remote vibrometry are limited by low signal-to-noise ratios and lack of filtering of optical signals returned from targets. The proposed development would overcome these limitations. A system as proposed would include a narrow-band laser as its target illuminator, a lock-in-detection receiver subsystem, and a laser-power-control subsystem that would utilize feedback of the intensity of background illumination of the target to adjust the laser power. The laser power would be set at a level high enough to enable the desired measurements but below the threshold of detectability by an imaginary typical modern photodetector located at the target and there exposed to the background illumination. The laser beam would be focused tightly on the distant target, such that the receiving optics would be exposed to only one speckle. The return signal would be extremely-narrow-band filtered (to sub-kilohertz bandwidth) in the optical domain by a whispering-gallery- mode filter so as to remove most of the background illumination. The filtered optical signal would be optically amplified. This combination of optical filtering and optical amplification would provide an optical signal that would be strong enough to be detectable but not so strong as to saturate the detector in the lock-in detection subsystem.

Laser projection positioning of spatial contour curves via a galvanometric scanner

NASA Astrophysics Data System (ADS)

Tu, Junchao; Zhang, Liyan

2018-04-01

The technology of laser projection positioning is widely applied in advanced manufacturing fields (e.g. composite plying, parts location and installation). In order to use it better, a laser projection positioning (LPP) system is designed and implemented. Firstly, the LPP system is built by a laser galvanometric scanning (LGS) system and a binocular vision system. Applying Single-hidden Layer Feed-forward Neural Network (SLFN), the system model is constructed next. Secondly, the LGS system and the binocular system, which are respectively independent, are integrated through a datadriven calibration method based on extreme learning machine (ELM) algorithm. Finally, a projection positioning method is proposed within the framework of the calibrated SLFN system model. A well-designed experiment is conducted to verify the viability and effectiveness of the proposed system. In addition, the accuracy of projection positioning are evaluated to show that the LPP system can achieves the good localization effect.

Ultraviolet, visible, and infrared laser delivery using laser-to-fiber coupling via a grazing-incidence-based hollow taper

NASA Astrophysics Data System (ADS)

Ilev, Ilko K.; Waynant, Ronald W.

2001-01-01

We present a novel all-optical-waveguide method for ultraviolet (UV), visible (VIS) and infrared (IR) laser delivery including a lens-free method of laser-to-fiber coupling using a simple uncoated glass hollow taper. Based on the grazing incidence effect, the hollow taper provides a way of direct launching, without any intermediate focusing elements, high power laser radiation into delivery fibers. Because of the mutual action of the nearly parallel laser excitation, the mode coupling process, and mode filtering effect, the hollow taper serves as a mode converter that transforms the highly multimode profile of the input laser emission into a high-quality Gaussian-shaped profile at the taper output. When the grazing incidence effect of the taper is applied to laser delivery, the maintenance of high reflectance coefficients in a wide spectral region allows to utilize the same uncoated hollow taper for laser radiation in the UV, VIS and IR ranges. Applying the experimental hollow-taper based delivery systems, we obtain high laser- to-taper and taper-to-fiber coupling efficiencies.

Robust Computer-Assisted Laser Treatment Using Real-Time Retinal Tracking

DTIC Science & Technology

2001-10-25

Abstract- We propose a new computerized system to accurately guide laser shots to the diseased areas within the retina based on predetermined...image registration I. INTRODUCTION Diabetic retinopathy resulting from long term diabetes mellitus is one of the common diseases that lead to choroidal...have a strong impact on the effectiveness of such procedures. In this work, we propose a new computerized treatment planning system for laser treatment

Fast Optical Hazard Detection for Planetary Rovers Using Multiple Spot Laser Triangulation

NASA Technical Reports Server (NTRS)

Matthies, L.; Balch, T.; Wilcox, B.

1997-01-01

A new laser-based optical sensor system that provides hazard detection for planetary rovers is presented. It is anticipated that the sensor can support safe travel at speeds up to 6cm/second for large (1m) rovers in full sunlight on Earth or Mars. The system overcomes limitations in an older design that require image differencing ot detect a laser stripe in full sun.

Using Stars to Align a Steered Laser System for Cosmic Ray Simulation

NASA Astrophysics Data System (ADS)

Krantz, Harry; Wiencke, Lawrence

2016-03-01

Ultra high energy cosmic rays (UHECRs) are the highest energy cosmic particles with kinetic energy above 1018eV . UHECRs are detected from the air shower of secondary particles and UV florescence that results from interaction with the atmosphere. A high power UV laser beam can be used to simulate the optical signature of a UHCER air shower. The Global Light System (GLS) is a planned network of ground-based light sources including lasers to support the planned space-based Extreme Universe Space Observatory (EUSO). A portable prototype GLS laser station has been constructed at the Colorado School of Mines. Currently the laser system uses reference targets on the ground but stars can be used to better align the beam by providing a complete hemisphere of targets. In this work, a CCD camera is used to capture images of known stars through the steering head optics. The images are analyzed to find the steering head coordinates of the target star. The true coordinates of the star are calculated from the location and time of observation. A universal adjustment for the steering head is determined from the differences between the two pairs of coordinates across multiple stars. This laser system prototype will also be used for preflight tests of the ESUO Super Pressure Balloon mission.

Development of a red diode laser system for photodynamic therapy

NASA Astrophysics Data System (ADS)

Halkiotis, Konstantinos N.; Yova, Dido M.; Uzunoglou, Nikolaos K.; Papastergiou, Georgios; Matakias, Sotiris; Koukouvinos, Ilias

1998-07-01

The effectiveness of photodynamic treatment modality has been proven experimentally for a large variety of tumors, during the last years. This therapy utilizes the combined action of light and photosensitizing drug. Until now, a disadvantage of PDT has be the low tissue penetration of light, at the wavelengths of most commonly available lasers, for clinical studies. The red wavelength offers the advantage of increased penetration depth in tissue, in addition several new wavelength offers the advantage of increased penetration depth in tissue, in addition several new photosensitizers present absorption band at the region 630nm to 690nm. The development of high power red diode laser system for photodynamic therapy, has provided a cost effective alternative to existing lasers for use in PDT. This paper will describe the system design, development and performance of a diode laser system, connected with a fiber optic facility, to be used for PDT. The system was based on a high power semiconductor diode laser emitting at 655nm. The laser output power was approximately 60mW at the output of a 62.5/125/900 micron fiber optic probe. FUll technical details and optical performance characteristics of the system will be discussed in this paper.

Efficient generation of 1.9  W yellow light by cascaded frequency doubling of a distributed Bragg reflector tapered diode.

PubMed

Hansen, A K; Christensen, M; Noordegraaf, D; Heist, P; Papastathopoulos, E; Loyo-Maldonado, V; Jensen, O B; Skovgaard, P M W

2016-11-10

Watt-level yellow emitting lasers are interesting for medical applications, due to their high hemoglobin absorption, and for efficient detection of certain fluorophores. In this paper, we demonstrate a compact and robust diode-based laser system in the yellow spectral range. The system generates 1.9 W of single-frequency light at 562.4 nm by cascaded single-pass frequency doubling of the 1124.8 nm emission from a distributed Bragg reflector (DBR) tapered laser diode. The absence of a free-space cavity makes the system stable over a base-plate temperature range of 30 K. At the same time, the use of a laser diode enables the modulation of the pump wavelength by controlling the drive current. This is utilized to achieve a power modulation depth above 90% for the second harmonic light, with a rise time below 40  μs.

Shape memory polymer (SMP) gripper with a release sensing system

DOEpatents

Maitland, Duncan J.; Lee, Abraham P.; Schumann, Daniel L.; Silva, Luiz Da

2000-01-01

A system for releasing a target material, such as an embolic coil from an SMP located at the end of a catheter utilizing an optical arrangement for releasing the material. The system includes a laser, laser driver, display panel, photodetector, fiber optics coupler, fiber optics and connectors, a catheter, and an SMP-based gripper, and includes a release sensing and feedback arrangement. The SMP-based gripper is heated via laser light through an optic fiber causing the gripper to release a target material (e.g., embolic coil for therapeutic treatment of aneurysms). Various embodiments are provided for coupling the laser light into the SMP, which includes specific positioning of the coils, removal of the fiber cladding adjacent the coil, a metal coating on the SMP, doping the SMP with a gradient absorbing dye, tapering the fiber optic end, coating the SMP with low refractive index material, and locating an insert between the fiber optic and the coil.

Producing a Linear Laser System for 3d Modelimg of Small Objects

NASA Astrophysics Data System (ADS)

Amini, A. Sh.; Mozaffar, M. H.

2012-07-01

Today, three dimensional modeling of objects is considered in many applications such as documentation of ancient heritage, quality control, reverse engineering and animation In this regard, there are a variety of methods for producing three-dimensional models. In this paper, a 3D modeling system is developed based on photogrammetry method using image processing and laser line extraction from images. In this method the laser beam profile is radiated on the body of the object and with video image acquisition, and extraction of laser line from the frames, three-dimensional coordinates of the objects can be achieved. In this regard, first the design and implementation of hardware, including cameras and laser systems was conducted. Afterwards, the system was calibrated. Finally, the software of the system was implemented for three dimensional data extraction. The system was investigated for modeling a number of objects. The results showed that the system can provide benefits such as low cost, appropriate speed and acceptable accuracy in 3D modeling of objects.

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

Criteria for the evaluation of laser solar energy converter systems

NASA Technical Reports Server (NTRS)

Harries, W. L.

1985-01-01

Assuming that a parabolic insolation-collection mirror-based solar pumped laser has a collector and heat emitter whose weights are proportional to their areas, and that the weight of the laser is negligible by comparison, the output power/unit weight can be expressed in terms of the efficiencies and working temperatures of the system. This ratio appears to be several times higher for an IBr laser than for one operating on C3F7I, because the solar utilization efficiency is greater for the former despite its lower working temperature.

Diffraction-limited 577 nm true-yellow laser by frequency doubling of a tapered diode laser

NASA Astrophysics Data System (ADS)

Christensen, Mathias; Vilera, Mariafernanda; Noordegraaf, Danny; Hansen, Anders K.; Buß, Thomas; Jensen, Ole B.; Skovgaard, Peter M. W.

2018-02-01

A wide range of laser medical treatments are based on coagulation of blood by absorption of the laser radiation. It has, therefore, always been a goal of these treatments to maximize the ratio of absorption in the blood to that in the surrounding tissue. For this purpose lasers at 577 nm are ideal since this wavelength is at the peak of the absorption in oxygenated hemoglobin. Furthermore, 577 nm has a lower absorption in melanin when compared to green wavelengths (515 - 532 nm), giving it an advantage when treating at greater penetration depth. Here we present a laser system based on frequency doubling of an 1154 nm Distributed Bragg Reflector (DBR) tapered diode laser, emitting 1.1 W of single frequency and diffraction limited yellow light at 577 nm, corresponding to a conversion efficiency of 30.5%. The frequency doubling is performed in a single pass configuration using a cascade of two bulk non-linear crystals. The system is power stabilized over 10 hours with a standard deviation of 0.13% and the relative intensity noise is measured to be 0.064 % rms.

Research for the jamming mechanism of high-frequency laser to the laser seeker

NASA Astrophysics Data System (ADS)

Zheng, Xingyuan; Zhang, Haiyang; Wang, Yunping; Feng, Shuang; Zhao, Changming

2013-08-01

High-frequency laser will be able to enter the enemy laser signal processing systems without encoded identification and a copy. That makes it one of the research directions of new interference sources. In order to study the interference mechanism of high-frequency laser to laser guided weapons. According to the principle of high-frequency laser interference, a series of related theoretical models such as a semi-active laser seeker coded identification model, a time door model, multi-signal processing model and a interference signal modulation processing model are established. Then seeker interfere with effective 3σ criterion is proposed. Based on this, the study of the effect of multi-source interference and signal characteristics of the effect of high repetition frequency laser interference are key research. According to the simulation system testing, the results show that the multi-source interference and interference signal frequency modulation can effectively enhance the interference effect. While the interference effect of the interference signal amplitude modulation is not obvious. The research results will provide the evaluation of high-frequency laser interference effect and provide theoretical references for high-frequency laser interference system application.

Research on range-gated laser active imaging seeker

NASA Astrophysics Data System (ADS)

You, Mu; Wang, PengHui; Tan, DongJie

2013-09-01

Compared with other imaging methods such as millimeter wave imaging, infrared imaging and visible light imaging, laser imaging provides both a 2-D array of reflected intensity data as well as 2-D array of range data, which is the most important data for use in autonomous target acquisition .In terms of application, it can be widely used in military fields such as radar, guidance and fuse. In this paper, we present a laser active imaging seeker system based on range-gated laser transmitter and sensor technology .The seeker system presented here consist of two important part, one is laser image system, which uses a negative lens to diverge the light from a pulse laser to flood illuminate a target, return light is collected by a camera lens, each laser pulse triggers the camera delay and shutter. The other is stabilization gimbals, which is designed to be a rotatable structure both in azimuth and elevation angles. The laser image system consists of transmitter and receiver. The transmitter is based on diode pumped solid-state lasers that are passively Q-switched at 532nm wavelength. A visible wavelength was chosen because the receiver uses a Gen III image intensifier tube with a spectral sensitivity limited to wavelengths less than 900nm.The receiver is image intensifier tube's micro channel plate coupled into high sensitivity charge coupled device camera. The image has been taken at range over one kilometer and can be taken at much longer range in better weather. Image frame frequency can be changed according to requirement of guidance with modifiable range gate, The instantaneous field of views of the system was found to be 2×2 deg. Since completion of system integration, the seeker system has gone through a series of tests both in the lab and in the outdoor field. Two different kinds of buildings have been chosen as target, which is located at range from 200m up to 1000m.To simulate dynamic process of range change between missile and target, the seeker system has been placed on the truck vehicle running along the road in an expected speed. The test result shows qualified image and good performance of the seeker system.

All-Fiber Configuration Laser Self-Mixing Doppler Velocimeter Based on Distributed Feedback Fiber Laser

PubMed Central

Wu, Shuang; Wang, Dehui; Xiang, Rong; Zhou, Junfeng; Ma, Yangcheng; Gui, Huaqiao; Liu, Jianguo; Wang, Huanqin; Lu, Liang; Yu, Benli

2016-01-01

In this paper, a novel velocimeter based on laser self-mixing Doppler technology has been developed for speed measurement. The laser employed in our experiment is a distributed feedback (DFB) fiber laser, which is an all-fiber structure using only one Fiber Bragg Grating to realize optical feedback and wavelength selection. Self-mixing interference for optical velocity sensing is experimentally investigated in this novel system, and the experimental results show that the Doppler frequency is linearly proportional to the velocity of a moving target, which agrees with the theoretical analysis commendably. In our experimental system, the velocity measurement can be achieved in the range of 3.58 mm/s–2216 mm/s with a relative error under one percent, demonstrating that our novel all-fiber configuration velocimeter can implement wide-range velocity measurements with high accuracy. PMID:27472342

Systems analysis for ground-based optical navigation

NASA Technical Reports Server (NTRS)

Null, G. W.; Owen, W. M., Jr.; Synnott, S. P.

1992-01-01

Deep-space telecommunications systems will eventually operate at visible or near-infrared regions to provide increased information return from interplanetary spacecraft. This would require an onboard laser transponder in place of (or in addition to) the usual microwave transponder, as well as a network of ground-based and/or space-based optical observing stations. This article examines the expected navigation systems to meet these requirements. Special emphasis is given to optical astrometric (angular) measurements of stars, solar system target bodies, and (when available) laser-bearing spacecraft, since these observations can potentially provide the locations of both spacecraft and target bodies. The role of astrometry in the navigation system and the development options for astrometric observing systems are also discussed.

Optical-fiber-based laser-induced breakdown spectroscopy for detection of early caries

NASA Astrophysics Data System (ADS)

Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

2015-06-01

A laser-induced breakdown spectroscopy (LIBS) system targeting for the in vivo analysis of tooth enamel is described. The system is planned to enable real-time analysis of teeth during laser dental treatment by utilizing a hollow optical fiber that transmits both Q-switched Nd:YAG laser light for LIBS and infrared Er:YAG laser light for tooth ablation. The sensitivity of caries detection was substantially improved by expanding the spectral region under analysis to ultraviolet (UV) light and by focusing on emission peaks of Zn in the UV region. Subsequently, early caries were distinguished from healthy teeth with accuracy rates above 80% in vitro.

A Real-Time Terahertz Time-Domain Polarization Analyzer with 80-MHz Repetition-Rate Femtosecond Laser Pulses

PubMed Central

Watanabe, Shinichi; Yasumatsu, Naoya; Oguchi, Kenichi; Takeda, Masatoshi; Suzuki, Takeshi; Tachizaki, Takehiro

2013-01-01

We have developed a real-time terahertz time-domain polarization analyzer by using 80-MHz repetition-rate femtosecond laser pulses. Our technique is based on the spinning electro-optic sensor method, which we recently proposed and demonstrated by using a regenerative amplifier laser system; here we improve the detection scheme in order to be able to use it with a femtosecond laser oscillator with laser pulses of a much higher repetition rate. This improvement brings great advantages for realizing broadband, compact and stable real-time terahertz time-domain polarization measurement systems for scientific and industrial applications. PMID:23478599

Electrical injection Ga(AsBi)/(AlGa)As single quantum well laser

NASA Astrophysics Data System (ADS)

Ludewig, P.; Knaub, N.; Hossain, N.; Reinhard, S.; Nattermann, L.; Marko, I. P.; Jin, S. R.; Hild, K.; Chatterjee, S.; Stolz, W.; Sweeney, S. J.; Volz, K.

2013-06-01

The Ga(AsBi) material system opens opportunities in the field of high efficiency infrared laser diodes. We report on the growth, structural investigations, and lasing properties of dilute bismide Ga(AsBi)/(AlGa)As single quantum well lasers with 2.2% Bi grown by metal organic vapor phase epitaxy on GaAs (001) substrates. Electrically injected laser operation at room temperature is achieved with a threshold current density of 1.56 kA/cm2 at an emission wavelength of ˜947 nm. These results from broad area devices show great promise for developing efficient IR laser diodes based on this emerging materials system.

Double wedge prism based beam deflector for precise laser beam steering

NASA Astrophysics Data System (ADS)

Tyszka, Krzysztof; Dobosz, Marek; Bilaszewski, Tomasz

2018-02-01

Aiming to increase laser beam pointing stability required in interferometric measurements, we designed a laser beam deflector intended for active laser beam stabilization systems. The design is based on two wedge-prisms: the deflecting wedge driven by a tilting piezo-platform and the fixed wedge to compensate initial beam deflection. Our design allows linear beam steering, independently in the horizontal or vertical direction, with resolution of less than 1 μrad in a range of more than 100 μrad, and no initial deflection of the beam. Moreover, the ratio of the output beam deflection angle and the wedge tilt angle is less than 0.1; therefore, the noise influence is significantly reduced in comparison to standard mirror-based deflectors. The theoretical analyses support the designing process and can serve as a guide to wedge-prism selection. The experimental results are in agreement with theory and confirm the advantages of the presented double wedge system.

Welding of Vanadium, Tantalum, 304L and 21-6-9 Stainless Steels, and Titanium Alloys at Lawrence Livermore National Laboratory using a Fiber Delivered 2.2 kW Diode Pumped CW Nd:YAG Laser

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

Palmer, T; Elmer, J; Pong, R

This report summarizes the results of a series of laser welds made between 2003 and 2005 at Lawrence Livermore National Laboratory (LLNL). The results are a compilation of several, previously unpublished, internal LLNL reports covering the laser welding of vanadium, tantalum, 304L stainless steel, 21-6-9 (Nitronic 40) steel, and Ti-6Al-4V. All the welds were made using a Rofin Sinar DY-022 diode pumped continuous wave Nd:YAG laser. Welds are made at sharp focus on each material at various power levels and travel speeds in order to provide a baseline characterization of the performance of the laser welder. These power levels aremore » based on measurements of the output power of the laser system, as measured by a power meter placed at the end of the optics train. Based on these measurements, it appears that the system displays a loss of approximately 10% as the beam passes through the fiber optic cable and laser optics. Since the beam is delivered to the fixed laser optics through a fiber optic cable, the effects of fiber diameter are also briefly investigated. Because the system utilizes 1:1 focusing optics, the laser spot size at sharp focus generally corresponds to the diameter of the fiber with which the laser is delivered. Differences in the resulting weld penetration in the different materials system are prevalent, with the welds produced on the Nitronic 40 material displaying the highest depths (> 5 mm) and minimal porosity. A Primes focusing diagnostic has also been installed on this laser system and used to characterize the size and power density distribution of the beams as a function of both power and focus position. Further work is planned in which this focusing diagnostic will be used to better understand the effects of changes in beam properties on the resulting weld dimensions in these and other materials systems.« less

Odometry and Laser Scanner Fusion Based on a Discrete Extended Kalman Filter for Robotic Platooning Guidance

PubMed Central

Espinosa, Felipe; Santos, Carlos; Marrón-Romera, Marta; Pizarro, Daniel; Valdés, Fernando; Dongil, Javier

2011-01-01

This paper describes a relative localization system used to achieve the navigation of a convoy of robotic units in indoor environments. This positioning system is carried out fusing two sensorial sources: (a) an odometric system and (b) a laser scanner together with artificial landmarks located on top of the units. The laser source allows one to compensate the cumulative error inherent to dead-reckoning; whereas the odometry source provides less pose uncertainty in short trajectories. A discrete Extended Kalman Filter, customized for this application, is used in order to accomplish this aim under real time constraints. Different experimental results with a convoy of Pioneer P3-DX units tracking non-linear trajectories are shown. The paper shows that a simple setup based on low cost laser range systems and robot built-in odometry sensors is able to give a high degree of robustness and accuracy to the relative localization problem of convoy units for indoor applications. PMID:22164079

Odometry and laser scanner fusion based on a discrete extended Kalman Filter for robotic platooning guidance.

PubMed

Espinosa, Felipe; Santos, Carlos; Marrón-Romera, Marta; Pizarro, Daniel; Valdés, Fernando; Dongil, Javier

2011-01-01

This paper describes a relative localization system used to achieve the navigation of a convoy of robotic units in indoor environments. This positioning system is carried out fusing two sensorial sources: (a) an odometric system and (b) a laser scanner together with artificial landmarks located on top of the units. The laser source allows one to compensate the cumulative error inherent to dead-reckoning; whereas the odometry source provides less pose uncertainty in short trajectories. A discrete Extended Kalman Filter, customized for this application, is used in order to accomplish this aim under real time constraints. Different experimental results with a convoy of Pioneer P3-DX units tracking non-linear trajectories are shown. The paper shows that a simple setup based on low cost laser range systems and robot built-in odometry sensors is able to give a high degree of robustness and accuracy to the relative localization problem of convoy units for indoor applications.

Geoscience laser altimeter system-stellar reference system

NASA Astrophysics Data System (ADS)

Millar, Pamela S.; Sirota, J. Marcos

1998-01-01

GLAS is an EOS space-based laser altimeter being developed to profile the height of the Earth's ice sheets with ~15 cm single shot accuracy from space under NASA's Mission to Planet Earth (MTPE). The primary science goal of GLAS is to determine if the ice sheets are increasing or diminishing for climate change modeling. This is achieved by measuring the ice sheet heights over Greenland and Antarctica to 1.5 cm/yr over 100 km×100 km areas by crossover analysis (Zwally 1994). This measurement performance requires the instrument to determine the pointing of the laser beam to ~5 urad (1 arcsecond), 1-sigma, with respect to the inertial reference frame. The GLAS design incorporates a stellar reference system (SRS) to relate the laser beam pointing angle to the star field with this accuracy. This is the first time a spaceborne laser altimeter is measuring pointing to such high accuracy. The design for the stellar reference system combines an attitude determination system (ADS) with a laser reference system (LRS) to meet this requirement. The SRS approach and expected performance are described in this paper.

Comparative assessment of erbium fiber ring lasers and reflective SOA linear lasers for fiber Bragg grating dynamic strain sensing.

PubMed

Wei, Heming; Krishnaswamy, Sridhar

2017-05-01

Fiber Bragg grating (FBG) dynamic strain sensors using both an erbium-based fiber ring laser configuration and a reflective semiconductor optical amplifier (RSOA)-based linear laser configuration are investigated theoretically and experimentally. Fiber laser models are first presented to analyze the output characteristics of both fiber laser configurations when the FBG sensor is subjected to dynamic strains at high frequencies. Due to differences in the transition times of erbium and the semiconductor (InP/InGaAsP), erbium-doped fiber amplifier (EDFA)- and RSOA-based fiber lasers exhibit different responses and regimes of stability when the FBG is subjected to dynamic strains. The responses of both systems are experimentally verified using an adaptive photorefractive two-wave mixing (TWM) spectral demodulation technique. The experimental results show that the RSOA-FBG fiber linear cavity laser is stable and can stably respond to dynamic strains at high frequencies. An example application using a multiplexed TWM interferometer to demodulate multiple FBG sensors is also discussed.

Laser-based sensor for a coolant leak detection in a nuclear reactor

NASA Astrophysics Data System (ADS)

Kim, T.-S.; Park, H.; Ko, K.; Lim, G.; Cha, Y.-H.; Han, J.; Jeong, D.-Y.

2010-08-01

Currently, the nuclear industry needs strongly a reliable detection system to continuously monitor a coolant leak during a normal operation of reactors for the ensurance of nuclear safety. In this work, we propose a new device for the coolant leak detection based on tunable diode laser spectroscopy (TDLS) by using a compact diode laser. For the feasibility experiment, we established an experimental setup consisted of a near-IR diode laser with a wavelength of about 1392 nm, a home-made multi-pass cell and a sample injection system. The feasibility test was performed for the detection of the heavy water (D2O) leaks which can happen in a pressurized heavy water reactor (PWHR). As a result, the device based on the TDLS is shown to be operated successfully in detecting a HDO molecule, which is generated from the leaked heavy water by an isotope exchange reaction between D2O and H2O. Additionally, it is suggested that the performance of the new device, such as sensitivity and stability, can be improved by adapting a cavity enhanced absorption spectroscopy and a compact DFB diode laser. We presume that this laser-based leak detector has several advantages over the conventional techniques currently employed in the nuclear power plant, such as radiation monitoring, humidity monitoring and FT-IR spectroscopy.

Laser diode side-pumped Nd:YVO4 microchip laser with film-etched microcavity mirrors.

PubMed

Li, Jiyang; Niu, Yanxiong; Chen, Sanbin; Tan, Yidong

2017-10-01

Microchip lasers are applied as the light sources on various occasions with the end-pumping scheme. However, the vibration, the temperature drift, or the mechanical deformation of the pumping light in laser diodes in the end-pumping scheme will lead to instability in the microchip laser output, which causes errors and malfunctioning in the optic systems. In this paper, the side-pumping scheme is applied for improving the disturbance-resisting ability of the microchip laser. The transverse mode and the frequency purity of the laser output are tested. To ensure unicity in the frequency of the laser output, numerical simulations based on Fresnel-Kirchhoff diffraction theory are conducted on the parameters of the microchip laser cavity. Film-etching technique is applied to restrain the area of the film and form the microcavity mirrors. The laser output with microcavity mirrors is ensured to be in single frequency and with good beam quality, which is significant in the applications of microchip lasers as the light sources in optical systems.

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

On-line surveillance of a dynamic process by a moving system based on pulsed digital holographic interferometry.

PubMed

Pedrini, Giancarlo; Alexeenko, Igor; Osten, Wolfgang; Schnars, Ulf

2006-02-10

A method based on pulsed digital holographic interferometry for the measurement of dynamic deformations of a surface by using a moving system is presented. The measuring system may move with a speed of several meters per minute and can measure deformation of the surface with an accuracy of better than 50 nm. The deformation is obtained by comparison of the wavefronts recorded at different times with different laser pulses produced by a Nd:YAG laser. The effect due to the movement of the measuring system is compensated for by digital processing of the different holograms. The system is well suited for on-line surveillance of a dynamic process such as laser welding and friction stir welding. Experimental results are presented, and the advantages of the method are discussed.

A novel computerized surgeon-machine interface for robot-assisted laser phonomicrosurgery.

PubMed

Mattos, Leonardo S; Deshpande, Nikhil; Barresi, Giacinto; Guastini, Luca; Peretti, Giorgio

2014-08-01

To introduce a novel computerized surgical system for improved usability, intuitiveness, accuracy, and controllability in robot-assisted laser phonomicrosurgery. Pilot technology assessment. The novel system was developed involving a newly designed motorized laser micromanipulator, a touch-screen display, and a graphics stylus. The system allows the control of a CO2 laser through interaction between the stylus and the live video of the surgical area. This empowers the stylus with the ability to have actual effect on the surgical site. Surgical enhancements afforded by this system were established through a pilot technology assessment using randomized trials comparing its performance with a state-of-the-art laser microsurgery system. Resident surgeons and medical students were chosen as subjects in performing sets of trajectory-following exercises. Image processing-based techniques were used for an objective performance assessment. A System Usability Scale-based questionnaire was used for the qualitative assessment. The computerized interface demonstrated superiority in usability, accuracy, and controllability over the state-of-the-art system. Significant ease of use and learning experienced by the subjects were demonstrated by the usability score assigned to the two compared interfaces: computerized interface = 83.96% versus state-of-the-art = 68.02%. The objective analysis showed a significant enhancement in accuracy and controllability: computerized interface = 90.02% versus state-of-the-art = 75.59%. The novel system significantly enhances the accuracy, usability, and controllability in laser phonomicrosurgery. The design provides an opportunity to improve the ergonomics and safety of current surgical setups. © 2014 The American Laryngological, Rhinological and Otological Society, Inc.

Land-Based Mobile Laser Scanning Systems: a Review

NASA Astrophysics Data System (ADS)

Puente, I.; González-Jorge, H.; Arias, P.; Armesto, J.

2011-09-01

Mobile mapping has been using various photogrammetric techniques for many years. In recent years, there has been an increase in the number of mobile mapping systems using laser scanners available in the market, partially because of the improvement in GNSS/INS performance for direct georeferencing. In this article, some of the most important land-based mobile laser scanning (MLS) systems are reviewed. Firstly, the main characteristics of MLS systems vs. airborne (ALS) and terrestrial laser scanning (TLS) systems are compared. Secondly, a short overview of the mobile mapping technology is also provided so that the reader can fully grasp the complexity and operation of these devices. As we put forward in this paper, a comparison of different systems is briefly carried out regarding specifications provided by the manufacturers. Focuses on the current research are also addressed with emphasis on the practical applications of these systems. Most of them have been utilized for data collection on road infrastructures or building façades. This article shows that MLS technology is nowadays well established and proven, since the demand has grown to the point that there are several systems suppliers offering their products to satisfy this particular market.

High temperature semiconductor diode laser pumps for high energy laser applications

NASA Astrophysics Data System (ADS)

Campbell, Jenna; Semenic, Tadej; Guinn, Keith; Leisher, Paul O.; Bhunia, Avijit; Mashanovitch, Milan; Renner, Daniel

2018-02-01

Existing thermal management technologies for diode laser pumps place a significant load on the size, weight and power consumption of High Power Solid State and Fiber Laser systems, thus making current laser systems very large, heavy, and inefficient in many important practical applications. To mitigate this thermal management burden, it is desirable for diode pumps to operate efficiently at high heat sink temperatures. In this work, we have developed a scalable cooling architecture, based on jet-impingement technology with industrial coolant, for efficient cooling of diode laser bars. We have demonstrated 60% electrical-to-optical efficiency from a 9xx nm two-bar laser stack operating with propylene-glycolwater coolant, at 50 °C coolant temperature. To our knowledge, this is the highest efficiency achieved from a diode stack using 50 °C industrial fluid coolant. The output power is greater than 100 W per bar. Stacks with additional laser bars are currently in development, as this cooler architecture is scalable to a 1 kW system. This work will enable compact and robust fiber-coupled diode pump modules for high energy laser applications.

Ripeness detection simulation of oil palm fruit bunches using laser-based imaging system

NASA Astrophysics Data System (ADS)

Shiddiq, Minarni; Fitmawati, Anjasmara, Ridho; Sari, Nurmaya; Hefniati

2017-01-01

Ripeness is one of important factors for quality sorting of harvested oil palm fresh fruit bunches (FFB). Traditional ripeness classifications using FFB color and number of fruit loose for harvesting have some disadvantages especially for high oil palm trees. A laser based imaging system is proposed to substitute the traditional method. In this study, ripeness detection simulation of oil palm FFBs was performed. The system composed of two diode lasers with 532 nm and 680 nm in wavelengths and a CMOS camera which was set on a rotating plate for easy adjustment of laser beam hitting FFB. The FFB samples were placed on an aluminum platform with 4 height variations, 1.5 m, 2 m, 2.5 m, and 3 m. The relations of reflectance intensities represented by Red Green Blue (RGB) values of the FFB images to the height variations and ripeness levels of FFBs with and without laser beam were analyzed. The samples were from Tenera variety with 4 ripeness levels called F0, F1, F3, and F4. The results showed that the red component of RGB values were dominant for FFBs without laser and with red laser. The average RGB values are higher for F3 (ripe) level and F4 (overripe). Imaging with green laser showed consistency. Imaging methods using laser was able to differentiate ripeness levels of oil palm fresh fruit bunch, it could be applied for future remote detection of oil palm FFB ripeness.

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.

Out of the Lab...Into the Real World

NASA Technical Reports Server (NTRS)

1999-01-01

Big Sky Laser Technologies of Bozeman, MT is a developer of compact, ruggedized commercial and developmental laser systems, including small medical lasers and Lidars used in NASA tracking applications. Company engineers developing new laser products determined that NASA technology for detection and control of prelasing in a Q-switched laser would be of value to them in at least two of their product lines. Big Sky Laser's CFR-800 unit is based on NASA technology to which they obtained a non-exclusive patent.

Laser assisted deposition

NASA Technical Reports Server (NTRS)

Dutta, S.

1983-01-01

Applications of laser-based processing techniques to solar cell metallization are discussed. Laser-assisted thermal or photolytic maskless deposition from organometallic vapors or solutions may provide a viable alternative to photovoltaic metallization systems currently in use. High power, defocused excimer lasers may be used in conjunction with masks as an alternative to direct laser writing to provide higher throughput. Repeated pulsing with excimer lasers may eliminate the need for secondary plating techniques for metal film buildup. A comparison between the thermal and photochemical deposition processes is made.

High removal rate laser-based coating removal system

DOEpatents

Matthews, Dennis L.; Celliers, Peter M.; Hackel, Lloyd; Da Silva, Luiz B.; Dane, C. Brent; Mrowka, Stanley

1999-11-16

A compact laser system that removes surface coatings (such as paint, dirt, etc.) at a removal rate as high as 1000 ft.sup.2 /hr or more without damaging the surface. A high repetition rate laser with multiple amplification passes propagating through at least one optical amplifier is used, along with a delivery system consisting of a telescoping and articulating tube which also contains an evacuation system for simultaneously sweeping up the debris produced in the process. The amplified beam can be converted to an output beam by passively switching the polarization of at least one amplified beam. The system also has a personal safety system which protects against accidental exposures.

Mie resonances to tailor random lasers

NASA Astrophysics Data System (ADS)

García, P. D.; Ibisate, M.; Sapienza, R.; Wiersma, D. S.; López, C.

2009-07-01

In this paper, we present an optical characterization of photonic glass-based random lasers. We show how the resonant behavior of diffuse light transport through such systems can tailor the lasing emission when a gain medium is added to the glass. A DNA-based organic dye is used as gain medium. The resonances in the transport mean-free path influence the lasing wavelength of the random laser. The laser wavelength is therefore controlled by the sphere diameter. Furthermore, the existence of Mie resonances reduces the necessary pump energy to reach the lasing threshold.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: On the possibility of development of a photochemical unit based on an NH3 laser with an intracavity reactor

NASA Astrophysics Data System (ADS)

Apatin, V. M.; Belokurov, A. N.; Makarov, Grigorii N.; Mendoza, P.; Petin, A. N.; Pigul'skii, S. V.; Rios, I.; Ryabov, Evgenii A.

2006-03-01

The possibility of developing a photochemical setup on the basis of an optically pumped ammonia laser with an intracavity photoreactor is proved. The obtained values of the cavity 'implication' factor γ are comparable with those of intracavity systems based on a CO2 laser. The conditions for achieving the maximum energy in the focusing cavity are determined and the ways to control the shape of its caustic are indicated.

The Use of Lasers in Disinfection and Cleanliness of Root Canals: a Review

PubMed Central

Anić, Ivica

2014-01-01

The outcome of root canal treatment is based on efficient disinfection of the root canal system and prevention of reinfection. Current chemomechanical cleaning methods do not always achieve these goals, and insufficient root canal disinfection is the main reason for endodontic failure. Due to high energy content and specific characteristics of laser light, laser treatment has been proposed for cleaning and disinfecting the root canal system. This paper reviews the literature covering the effect of Er:YAG, Er,Cr:YSGG, Nd:YAG and diode laser on the root canal wall in the removal of smear layer and against intracanal bacteria. Recently, the use of laser energy to induce cavitation and acoustic streaming of intracanal irrigants has been investigated. Based on recent literature, it can be concluded that lasers have bactericidal effects. However, they still cannot replace sodium hypochlorite and should be considered as an adjunct to the current chemical root canal disinfection protocols. Certain lasers can help in removing the smear layer and debris and can modify the morphology of the root canal wall. Unfortunately, there have not been enough randomized clinical studies evaluating endodontic treatment outcome following the use of laser. PMID:27688346

Low-photon-number optical switch and AND/OR logic gates based on quantum dot-bimodal cavity coupling system.

PubMed

Ma, Shen; Ye, Han; Yu, Zhong-Yuan; Zhang, Wen; Peng, Yi-Wei; Cheng, Xiang; Liu, Yu-Min

2016-01-11

We propose a new scheme based on quantum dot-bimodal cavity coupling system to realize all-optical switch and logic gates in low-photon-number regime. Suppression of mode transmission due to the destructive interference effect is theoretically demonstrated by driving the cavity with two orthogonally polarized pulsed lasers at certain pulse delay. The transmitted mode can be selected by designing laser pulse sequence. The optical switch with high on-off ratio emerges when considering one driving laser as the control. Moreover, the AND/OR logic gates based on photon polarization are achieved by cascading the coupling system. Both proposed optical switch and logic gates work well in ultra-low energy magnitude. Our work may enable various applications of all-optical computing and quantum information processing.

Low-photon-number optical switch and AND/OR logic gates based on quantum dot-bimodal cavity coupling system

PubMed Central

Ma, Shen; Ye, Han; Yu, Zhong-Yuan; Zhang, Wen; Peng, Yi-Wei; Cheng, Xiang; Liu, Yu-Min

2016-01-01

We propose a new scheme based on quantum dot-bimodal cavity coupling system to realize all-optical switch and logic gates in low-photon-number regime. Suppression of mode transmission due to the destructive interference effect is theoretically demonstrated by driving the cavity with two orthogonally polarized pulsed lasers at certain pulse delay. The transmitted mode can be selected by designing laser pulse sequence. The optical switch with high on-off ratio emerges when considering one driving laser as the control. Moreover, the AND/OR logic gates based on photon polarization are achieved by cascading the coupling system. Both proposed optical switch and logic gates work well in ultra-low energy magnitude. Our work may enable various applications of all-optical computing and quantum information processing. PMID:26750557

QUANTITATIVE DETECTION OF ENVIRONMENTALLY IMPORTANT DYES USING DIODE LASER/FIBER-OPTIC RAMAN

EPA Science Inventory

A compact diode laser/fiber-optic Raman spectrometer is used for quantitative detection of environmentally important dyes. This system is based on diode laser excitation at 782 mm, fiber optic probe technology, an imaging spectrometer, and state-of-the-art scientific CCD camera. ...

Q-switched slab RF discharge CO laser

NASA Astrophysics Data System (ADS)

Ionin, A. A.; Kochetkov, Yu V.; Kozlov, A. Yu; Mokrousova, D. V.; Seleznev, L. V.; Sinitsyn, D. V.; Sunchugasheva, E. S.; Zemtsov, D. S.

2017-05-01

A compact repetitively pulsed cryogenically cooled slab RF discharge CO laser with double path V-type laser resonator equipped with external Q-switching system based on rotating mirror was developed and studied. The laser produced mid-IR (λ ~ 5-7 µm) radiation pulses of ~1 ÷ 2 µs duration (FWHM), peak power up to ~3 kW, and pulse repetition rate up to 130 Hz. Averaged output laser power reached 0.5 W, the laser spectrum consisted of ~80 laser lines with individual peak power up to 80 W.

Torsional vibration measurements on rotating shaft system using laser doppler vibrometer

NASA Astrophysics Data System (ADS)

Xiang, Ling; Yang, Shixi; Gan, Chunbiao

2012-11-01

In this work, a laser torsional vibrameter was used to measure the torsion vibration of a rotating shaft system under electrical network impact. Based on the principles of laser Doppler velocimetry, the laser torsional vibrometer (LTV) are non-contact measurement of torsional oscillation of rotating shafts, offering significant advantages over conventional techniques. Furthermore, a highly complex shafting system is analyzed by a modified Riccati torsional transfer matrix. The system is modeled as a chain consisting of an elastic spring with concentrated mass points, and the multi-segments lumped mass model is established for this shafting system. By the modified Riccati torsional transfer matrix method, an accumulated calculation is effectively eliminated to obtain the natural frequencies. The electrical network impacts can activize the torsional vibration of shaft system, and the activized torsion vibration frequencies contained the natural frequencies of shaft system. The torsional vibrations of the shaft system were measured under electrical network impacts in laser Doppler torsional vibrometer. By comparisons, the natural frequencies by measurement were consistent with the values by calculation. The results verify the instrument is robust, user friendly and can be calibrated in situ. The laser torsional vibrometer represents a significant step forward in rotating machinery diagnostics.

Rapid and high-resolution stable isotopic measurement of biogenic accretionary carbonate using an online CO2 laser ablation system: Standardization of the analytical protocol.

PubMed

Sreemany, Arpita; Bera, Melinda Kumar; Sarkar, Anindya

2017-12-30

The elaborate sampling and analytical protocol associated with conventional dual-inlet isotope ratio mass spectrometry has long hindered high-resolution climate studies from biogenic accretionary carbonates. Laser-based on-line systems, in comparison, produce rapid data, but suffer from unresolvable matrix effects. It is, therefore, necessary to resolve these matrix effects to take advantage of the automated laser-based method. Two marine bivalve shells (one aragonite and one calcite) and one fish otolith (aragonite) were first analysed using a CO 2 laser ablation system attached to a continuous flow isotope ratio mass spectrometer under different experimental conditions (different laser power, sample untreated vs vacuum roasted). The shells and the otolith were then micro-drilled and the isotopic compositions of the powders were measured in a dual-inlet isotope ratio mass spectrometer following the conventional acid digestion method. The vacuum-roasted samples (both aragonite and calcite) produced mean isotopic ratios (with a reproducibility of ±0.2 ‰ for both δ 18 O and δ 13 C values) almost identical to the values obtained using the conventional acid digestion method. As the isotopic ratio of the acid digested samples fall within the analytical precision (±0.2 ‰) of the laser ablation system, this suggests the usefulness of the method for studying the biogenic accretionary carbonate matrix. When using laser-based continuous flow isotope ratio mass spectrometry for the high-resolution isotopic measurements of biogenic carbonates, the employment of a vacuum-roasting step will reduce the matrix effect. This method will be of immense help to geologists and sclerochronologists in exploring short-term changes in climatic parameters (e.g. seasonality) in geological times. Copyright © 2017 John Wiley & Sons, Ltd.

Laser-based pedestrian tracking in outdoor environments by multiple mobile robots.

PubMed

Ozaki, Masataka; Kakimuma, Kei; Hashimoto, Masafumi; Takahashi, Kazuhiko

2012-10-29

This paper presents an outdoors laser-based pedestrian tracking system using a group of mobile robots located near each other. Each robot detects pedestrians from its own laser scan image using an occupancy-grid-based method, and the robot tracks the detected pedestrians via Kalman filtering and global-nearest-neighbor (GNN)-based data association. The tracking data is broadcast to multiple robots through intercommunication and is combined using the covariance intersection (CI) method. For pedestrian tracking, each robot identifies its own posture using real-time-kinematic GPS (RTK-GPS) and laser scan matching. Using our cooperative tracking method, all the robots share the tracking data with each other; hence, individual robots can always recognize pedestrians that are invisible to any other robot. The simulation and experimental results show that cooperating tracking provides the tracking performance better than conventional individual tracking does. Our tracking system functions in a decentralized manner without any central server, and therefore, this provides a degree of scalability and robustness that cannot be achieved by conventional centralized architectures.

Ad hoc Laser networks component technology for modular spacecraft

NASA Astrophysics Data System (ADS)

Huang, Xiujun; Shi, Dele; Ma, Zongfeng; Shen, Jingshi

2016-03-01

Distributed reconfigurable satellite is a new kind of spacecraft system, which is based on a flexible platform of modularization and standardization. Based on the module data flow analysis of the spacecraft, this paper proposes a network component of ad hoc Laser networks architecture. Low speed control network with high speed load network of Microwave-Laser communication mode, no mesh network mode, to improve the flexibility of the network. Ad hoc Laser networks component technology was developed, and carried out the related performance testing and experiment. The results showed that ad hoc Laser networks components can meet the demand of future networking between the module of spacecraft.

Ad hoc laser networks component technology for modular spacecraft

NASA Astrophysics Data System (ADS)

Huang, Xiujun; Shi, Dele; Shen, Jingshi

2017-10-01

Distributed reconfigurable satellite is a new kind of spacecraft system, which is based on a flexible platform of modularization and standardization. Based on the module data flow analysis of the spacecraft, this paper proposes a network component of ad hoc Laser networks architecture. Low speed control network with high speed load network of Microwave-Laser communication mode, no mesh network mode, to improve the flexibility of the network. Ad hoc Laser networks component technology was developed, and carried out the related performance testing and experiment. The results showed that ad hoc Laser networks components can meet the demand of future networking between the module of spacecraft.

Precision Laser Development for Gravitational Wave Space Mission

NASA Technical Reports Server (NTRS)

Numata, Kenji; Camp, Jordan

2011-01-01

Optical fiber and semiconductor laser technologies have evolved dramatically over the last decade due to the increased demands from optical communications. We are developing a laser (master oscillator) and optical amplifier based on those technologies for interferometric space missions, such as the gravitational-wave mission LISA, and GRACE follow-on, by fully utilizing the mature wave-guided optics technologies. In space, where a simple and reliable system is preferred, the wave-guided components are advantageous over bulk, crystal-based, free-space laser, such as NPRO (Non-planar Ring Oscillator) and bulk-crystal amplifier, which are widely used for sensitive laser applications on the ground.

Optical damage testing at the Z-Backlighter facility at Sandia National Laboratories

NASA Astrophysics Data System (ADS)

Kimmel, Mark; Rambo, Patrick; Broyles, Robin; Geissel, Matthias; Schwarz, Jens; Bellum, John; Atherton, Briggs

2009-10-01

To enable laser-based radiography of high energy density physics events on the Z-Accelerator[4,5] at Sandia National Laboratories, a facility known as the Z-Backlighter has been developed. Two Nd:Phosphate glass lasers are used to create x-rays and/or proton beams capable of this radiographic diagnosis: Z-Beamlet (a multi-kilojoule laser operating at 527nm in a few nanoseconds) and Z-Petawatt (a several hundred joule laser operating at 1054nm in the subpicosecond regime) [1,2]. At the energy densities used in these systems, it is necessary to use high damage threshold optical materials, some of which are poorly characterized (especially for the sub-picosecond pulse). For example, Sandia has developed a meter-class dielectric coating capability for system optics. Damage testing can be performed by external facilities for nanosecond 532nm pulses, measuring high reflector coating damage thresholds >80J/cm2 and antireflection coating damage thresholds >20J/cm2 [3]. However, available external testing capabilities do not use femtosecond/picosecond scale laser pulses. To this end, we have constructed a sub-picoseond-laser-based optical damage test system. The damage tester system also allows for testing in a vacuum vessel, which is relevant since many optics in the Z-Backlighter system are used in vacuum. This paper will present the results of laser induced damage testing performed in both atmosphere and in vacuum, with 1054nm sub-picosecond laser pulses. Optical materials/coatings discussed are: bare fused silica and protected gold used for benchmarking; BK7; Zerodur; protected silver; and dielectric optical coatings (halfnia/silica layer pairs) produced by Sandia's in-house meter-class coating capability.

Beyond the random phase approximation: Stimulated Brillouin backscatter for finite laser coherence times

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

Korotkevich, Alexander O.; Lushnikov, Pavel M., E-mail: plushnik@math.unm.edu; Landau Institute for Theoretical Physics, 2 Kosygin Str., Moscow 119334

2015-01-15

We developed a linear theory of backward stimulated Brillouin scatter (BSBS) of a spatially and temporally random laser beam relevant for laser fusion. Our analysis reveals a new collective regime of BSBS (CBSBS). Its intensity threshold is controlled by diffraction, once cT{sub c} exceeds a laser speckle length, with T{sub c} the laser coherence time. The BSBS spatial gain rate is approximately the sum of that due to CBSBS, and a part which is independent of diffraction and varies linearly with T{sub c}. The CBSBS spatial gain rate may be reduced significantly by the temporal bandwidth of KrF-based laser systemsmore » compared to the bandwidth currently available to temporally smoothed glass-based laser systems.« less

Doublet Pulse Coherent Laser Radar for Tracking of Resident Space Objects

DTIC Science & Technology

2014-09-01

based laser systems can be limited by the effects of tumbling, extremely accurate Doppler measurement is possible using a doublet coherent laser ...Doublet pulse coherent laser radar for tracking of resident space objects Narasimha S. Prasad *1 , Van Rudd 2 , Scott Shald 2 , Stephan...Doublet Pulse Coherent Laser Radar for Tracking of Resident Space Objects 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S

Fast and automatic depth control of iterative bone ablation based on optical coherence tomography data

NASA Astrophysics Data System (ADS)

Fuchs, Alexander; Pengel, Steffen; Bergmeier, Jan; Kahrs, Lüder A.; Ortmaier, Tobias

2015-07-01

Laser surgery is an established clinical procedure in dental applications, soft tissue ablation, and ophthalmology. The presented experimental set-up for closed-loop control of laser bone ablation addresses a feedback system and enables safe ablation towards anatomical structures that usually would have high risk of damage. This study is based on combined working volumes of optical coherence tomography (OCT) and Er:YAG cutting laser. High level of automation in fast image data processing and tissue treatment enables reproducible results and shortens the time in the operating room. For registration of the two coordinate systems a cross-like incision is ablated with the Er:YAG laser and segmented with OCT in three distances. The resulting Er:YAG coordinate system is reconstructed. A parameter list defines multiple sets of laser parameters including discrete and specific ablation rates as ablation model. The control algorithm uses this model to plan corrective laser paths for each set of laser parameters and dynamically adapts the distance of the laser focus. With this iterative control cycle consisting of image processing, path planning, ablation, and moistening of tissue the target geometry and desired depth are approximated until no further corrective laser paths can be set. The achieved depth stays within the tolerances of the parameter set with the smallest ablation rate. Specimen trials with fresh porcine bone have been conducted to prove the functionality of the developed concept. Flat bottom surfaces and sharp edges of the outline without visual signs of thermal damage verify the feasibility of automated, OCT controlled laser bone ablation with minimal process time.

Inhibited-coupling HC-PCF based beam-delivery-system for high power green industrial lasers

NASA Astrophysics Data System (ADS)

Chafer, M.; Gorse, A.; Beaudou, B.; Lekiefs, Q.; Maurel, M.; Debord, B.; Gérôme, F.; Benabid, F.

2018-02-01

We report on an ultra-low loss Hollow-Core Photonic Crystal Fiber (HC-PCF) beam delivery system (GLO-GreenBDS) for high power ultra-short pulse lasers operating in the green spectral range (including 515 nm and 532 nm). The GLOBDS- Green combines ease-of-use, high laser-coupling efficiency, robustness and industrial compatible cabling. It comprises a pre-aligned laser-injection head, a sheath-cable protected HC-PCF and a modular fiber-output head. It enables fiber-core gas loading and evacuation in a hermetic fashion. A 5 m long GLO-BDS were demonstrated for a green short pulse laser with a transmission coefficient larger than 80%, and a laser output profile close to single-mode (M2 <1.3).

Phase-locking of combination-cylinder discharge CO2 laser

NASA Astrophysics Data System (ADS)

Xu, Yonggen

2014-05-01

A new type of laser resonator is presented to obtained good coherent beam and the parameters of the laser beam are calculated. The principle of phase-locking is described based on the injection-locking, the properties of the injected beam in the resonator are studied in detail. The output beam from output mirror is an annular laser beam with zero central intensity. An analytical expression for the annular laser beam through the ABCD optical system is derived. Typical numerical examples are calculated to confirm our analytical results. It is shown that the good coherent beam can be obtained through phase-locking, and the central intensity of annular beam through ABCD optical system will become maximum when the parameters of laser beam are selected reasonably.

A New Femtosecond Laser-Based Three-Dimensional Tomography Technique

NASA Astrophysics Data System (ADS)

Echlin, McLean P.

2011-12-01

Tomographic imaging has dramatically changed science, most notably in the fields of medicine and biology, by producing 3D views of structures which are too complex to understand in any other way. Current tomographic techniques require extensive time both for post-processing and data collection. Femtosecond laser based tomographic techniques have been developed in both standard atmosphere (femtosecond laser-based serial sectioning technique - FSLSS) and in vacuum (Tri-Beam System) for the fast collection (10 5mum3/s) of mm3 sized 3D datasets. Both techniques use femtosecond laser pulses to selectively remove layer-by-layer areas of material with low collateral damage and a negligible heat affected zone. To the authors knowledge, femtosecond lasers have never been used to serial section and these techniques have been entirely and uniquely developed by the author and his collaborators at the University of Michigan and University of California Santa Barbara. The FSLSS was applied to measure the 3D distribution of TiN particles in a 4330 steel. Single pulse ablation morphologies and rates were measured and collected from literature. Simultaneous two-phase ablation of TiN and steel matrix was shown to occur at fluences of 0.9-2 J/cm2. Laser scanning protocols were developed minimizing surface roughness to 0.1-0.4 mum for laser-based sectioning. The FSLSS technique was used to section and 3D reconstruct titanium nitride (TiN) containing 4330 steel. Statistical analysis of 3D TiN particle sizes, distribution parameters, and particle density were measured. A methodology was developed to use the 3D datasets to produce statistical volume elements (SVEs) for toughness modeling. Six FSLSS TiN datasets were sub-sampled into 48 SVEs for statistical analysis and toughness modeling using the Rice-Tracey and Garrison-Moody models. A two-parameter Weibull analysis was performed and variability in the toughness data agreed well with Ruggieri et al. bulk toughness measurements. The Tri-Beam system combines the benefits of laser based material removal (speed, low-damage, automated) with detectors that collect chemical, structural, and topological information. Multi-modal sectioning information was collected after many laser scanning passes demonstrating the capability of the Tri-Beam system.

Development Towards a Space Qualified Laser Stabilization System in Support of Space-Based Optical Interferometers

NASA Technical Reports Server (NTRS)

Seidel, David J.; Dubovitsky, Serge

2000-01-01

We report on the development, functional performance and space-qualification status of a laser stabilization system supporting a space-based metrology source used to measure changes in optical path lengths in space-based stellar interferometers. The Space Interferometry Mission (SIM) and Deep Space 3 (DS-3) are two missions currently funded by the National Aeronautics and Space Administration (NASA) that are space-based optical interferometers. In order to properly recombine the starlight received at each telescope of the interferometer it is necessary to perform high resolution laser metrology to stabilize the interferometer. A potentially significant error source in performing high resolution metrology length measurements is the potential for fluctuations in the laser gauge itself. If the laser frequency or wavelength is changing over time it will be misinterpreted as a length change in one of the legs of the interferometer. An analysis of the frequency stability requirement for SIM resulted in a fractional frequency stability requirement of square root (S(sub y)(f)) = <2 x 10(exp -12)/square root(Hz) at Fourier frequencies between 10 Hz and 1000 Hz. The DS-3 mission stability requirement is further increased to square root (S(sub y)(f)) = <5 x 10(exp -14)/Square root(Hz) at Fourier frequencies between 0.2 Hz and 10 kHz with a goal of extending the low frequency range to 0.05 Hz. The free running performance of the Lightwave Electronics NPRO lasers, which are the baseline laser for both SIM and DS-3 vary in stability and we have measured them to perform as follows (9 x l0(exp -11)/ f(Hz))(Hz)/square root(Hz)) = <( square root (S(sub y)(f)) = <(1.3 x l0(exp -8)/ f(Hz))/Square root(Hz). In order to improve the frequency stability of the laser we stabilize the laser to a high finesse optical cavity by locking the optical frequency of the laser to one of the transmission modes of the cavity. At JPL we have built a prototype space-qualifiable system meeting the stability requirements of SIM, which has been delivered to one of the SIM testbeds. We have also started on the development of a system to meet the stability needs of DS-3.

Optical system for UV-laser technological equipment

NASA Astrophysics Data System (ADS)

Fedosov, Yuri V.; Romanova, Galina E.; Afanasev, Maxim Ya.

2017-09-01

Recently there has been an intensive development of intelligent industrial equipment that is highly automated and can be rapidly adjusted for certain details. This equipment can be robotics systems, automatic wrappers and markers, CNC machines and 3D printers. The work equipment considered is the system for selective curing of photopolymers using a UV-laser and UV-radiation in such equipment that leads to additional technical difficulties. In many cases for transporting the radiation from the laser to the point processed, a multi-mirror system is used: however, such systems are usually difficult to adjust. Additionally, such multi-mirror systems are usually used as a part of the equipment for laser cutting of metals using high-power IR-lasers. For the UV-lasers, using many mirrors leads to crucial radiation losses because of many reflections. Therefore, during the development of the optical system for technological equipment using UV-laser we need to solve two main problems: to transfer the radiation for the working point with minimum losses and to include the system for controlling/handling the radiation spot position. We introduce a system for working with UV-lasers with 450mW of power and a wavelength of 0.45 μm based on a fiber system. In our modelling and design, we achieve spot sizes of about 300 μm, and the designed optical and mechanical systems (prototypes) were manufactured and assembled. In this paper, we present the layout of the technological unit, the results of the theoretical modelling of some parts of the system and some experimental results.

On-sky performance of the tip-tilt correction system for GLAS using an EMCCD camera

NASA Astrophysics Data System (ADS)

Skvarč, Jure; Tulloch, Simon

2008-07-01

Adaptive optics systems based on laser guide stars still need a natural guide star (NGS) to correct for the image motion caused by the atmosphere and by imperfect telescope tracking. The ability to properly compensate for this motion using a faint NGS is critical to achieve large sky coverage. For the laser guide system (GLAS) on the 4.2 m William Herschel Telescope we designed and tested in the laboratory and on-sky a tip-tilt correction system based on a PC running Linux and an EMCCD technology camera. The control software allows selection of different centroiding algorithms and loop control methods as well as the control parameters. Parameter analysis has been performed using tip-tilt only correction before the laser commissioning and the selected sets of parameters were then used during commissioning of the laser guide star system. We have established the SNR of the guide star as a function of magnitude, depending on the image sampling frequency and on the dichroic used in the optical system; achieving a measurable improvement using full AO correction with NGSes down to magnitude range R=16.5 to R=18. A minimum SNR of about 10 was established to be necessary for a useful correction. The system was used to produce 0.16 arcsecond images in H band using bright NGS and laser correction during GLAS commissioning runs.

Possible role of laser phototherapy in laser immunotherapy

NASA Astrophysics Data System (ADS)

Hode, Tomas; Hode, Lars

2009-02-01

Laser immunotherapy is a promising cancer treatment method that induces antitumor immunity and appears to be effective both locally and systemically. In this context, an important factor is the overall state of the immune system, both locally and systemically. The success of any immunotherapy treatment depends on the balance between the local immunosuppressive forces induced by the tumor and the immune response of the host organism. Factors that influence this balance include heat-shock proteins (for example HSP70), transforming growth factor β (TGF-β), tumor necrosis factor α (TNF-α), interleukins, and more. Laser phototherapy, which is based on non-thermal photobiological processes, has been shown to modulate the body's own immune response, both locally and systemically, with a strong influence on for example cytokine production and heat-shock protein synthesis. Laser phototherapy may therefore be an important component in the overall efficacy of laser immunotherapy, and may tip the balance between the immunosuppressive and immunostimulatory forces in favor of immunostimulation.

Detection of early caries by laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

2015-07-01

To improve sensitivity of dental caries detection by laser-induced breakdown spectroscopy (LIBS) analysis, it is proposed to utilize emission peaks in the ultraviolet. We newly focused on zinc whose emission peaks exist in ultraviolet because zinc exists at high concentration in the outer layer of enamel. It was shown that by using ratios between heights of an emission peak of Zn and that of Ca, the detection sensitivity and stability are largely improved. It was also shown that early caries are differentiated from healthy part by properly setting a threshold in the detected ratios. The proposed caries detection system can be applied to dental laser systems such as ones based on Er:YAG-lasers. When ablating early caries part by laser light, the system notices the dentist that the ablation of caries part is finished. We also show the intensity of emission peaks of zinc decreased with ablation with Er:YAG laser light.

Fiber lasers and amplifiers for science and exploration at NASA Goddard Space Flight Center

NASA Technical Reports Server (NTRS)

Krainak, Michael A.; Abshire, James; Allan, Graham R.; Stephen Mark

2005-01-01

We discuss present and near-term uses for high-power fiber lasers and amplifiers for NASA- specific applications including planetary topography and atmospheric spectroscopy. Fiber lasers and amplifiers offer numerous advantages for both near-term and future deployment of instruments on exploration and science remote sensing orbiting satellites. Ground-based and airborne systems provide an evolutionary path to space and a means for calibration and verification of space-borne systems. We present experimental progress on both the fiber transmitters and instrument prototypes for ongoing development efforts. These near-infrared instruments are laser sounders and lidars for measuring atmospheric carbon dioxide, oxygen, water vapor and methane and a pseudo-noise (PN) code laser ranging system. The associated fiber transmitters include high-power erbium, ytterbium, neodymium and Raman fiber amplifiers. In addition, we will discuss near-term fiber laser and amplifier requirements and programs for NASA free space optical communications, planetary topography and atmospheric spectroscopy.

Multi-point laser coherent detection system and its application on vibration measurement

NASA Astrophysics Data System (ADS)

Fu, Y.; Yang, C.; Xu, Y. J.; Liu, H.; Yan, K.; Guo, M.

2015-05-01

Laser Doppler vibrometry (LDV) is a well-known interferometric technique to measure the motions, vibrations and mode shapes of machine components and structures. The drawback of commercial LDV is that it can only offer a pointwise measurement. In order to build up a vibrometric image, a scanning device is normally adopted to scan the laser point in two spatial axes. These scanning laser Doppler vibrometers (SLDV) assume that the measurement conditions remain invariant while multiple and identical, sequential measurements are performed. This assumption makes SLDVs impractical to do measurement on transient events. In this paper, we introduce a new multiple-point laser coherent detection system based on spatial-encoding technology and fiber configuration. A simultaneous vibration measurement on multiple points is realized using a single photodetector. A prototype16-point laser coherent detection system is built and it is applied to measure the vibration of various objects, such as body of a car or a motorcycle when engine is on and under shock tests. The results show the prospect of multi-point laser coherent detection system in the area of nondestructive test and precise dynamic measurement.

Hybrid solid state laser system using a neodymium-based master oscillator and an ytterbium-based power amplifier

DOEpatents

Payne, Stephen A.; Marshall, Christopher D.; Powell, Howard T.; Krupke, William F.

2001-01-01

In a master oscillator-power amplifier (MOPA) hybrid laser system, the master oscillator (MO) utilizes a Nd.sup.3+ -doped gain medium and the power amplifier (PA) utilizes a diode-pumped Yb.sup.3+ -doped material. The use of two different laser gain media in the hybrid MOPA system provides advantages that are otherwise not available. The Nd-doped gain medium preferably serves as the MO because such gain media offer the lowest threshold of operation and have already been engineered as practical systems. The Yb-doped gain medium preferably serves in the diode-pumped PA to store pump energy effectively and efficiently by virtue of the long emission lifetime, thereby reducing diode pump costs. One crucial constraint on the MO and PA gain media is that the Nd and Yb lasers must operate at nearly the same wavelength. The 1.047 .mu.m Nd:YLF/Yb:S-FAP [Nd:LiYF.sub.4 /Yb:Sr.sub.5 (PO.sub.4).sub.3 F] hybrid MOPA system is a preferred embodiment of the hybrid Nd/Yb MOPA.

Terahertz quasi time-domain spectroscopy based on telecom technology for 1550 nm.

PubMed

Kohlhaas, Robert B; Rehn, Arno; Nellen, Simon; Koch, Martin; Schell, Martin; Dietz, Roman J B; Balzer, Jan C

2017-05-29

We present a fiber-coupled terahertz quasi time-domain spectroscopy system driven by a laser with a central wavelength of 1550 nm. By using a commercially available multimode laser diode in combination with state-of-the-art continuous wave antennas, a bandwidth of more than 1.8 THz is achieved. The peak signal-to-noise ratio is around 60 dB. A simulation based on the optical spectrum of the laser diode and the transfer function of the THz path is in agreement with the experimental results. The system is used to extract the refractive index from two different samples and the results indicate that the performance is up to 1.8 THz comparable to a terahertz time-domain spectroscopy 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

Evaluation method based on the image correlation for laser jamming image

NASA Astrophysics Data System (ADS)

Che, Jinxi; Li, Zhongmin; Gao, Bo

2013-09-01

The jamming effectiveness evaluation of infrared imaging system is an important part of electro-optical countermeasure. The infrared imaging devices in the military are widely used in the searching, tracking and guidance and so many other fields. At the same time, with the continuous development of laser technology, research of laser interference and damage effect developed continuously, laser has been used to disturbing the infrared imaging device. Therefore, the effect evaluation of the infrared imaging system by laser has become a meaningful problem to be solved. The information that the infrared imaging system ultimately present to the user is an image, so the evaluation on jamming effect can be made from the point of assessment of image quality. The image contains two aspects of the information, the light amplitude and light phase, so the image correlation can accurately perform the difference between the original image and disturbed image. In the paper, the evaluation method of digital image correlation, the assessment method of image quality based on Fourier transform, the estimate method of image quality based on error statistic and the evaluation method of based on peak signal noise ratio are analysed. In addition, the advantages and disadvantages of these methods are analysed. Moreover, the infrared disturbing images of the experiment result, in which the thermal infrared imager was interfered by laser, were analysed by using these methods. The results show that the methods can better reflect the jamming effects of the infrared imaging system by laser. Furthermore, there is good consistence between evaluation results by using the methods and the results of subjective visual evaluation. And it also provides well repeatability and convenient quantitative analysis. The feasibility of the methods to evaluate the jamming effect was proved. It has some extent reference value for the studying and developing on electro-optical countermeasures equipments and effectiveness evaluation.

Optoacoustic response from graphene-based solutions embedded in optical phantoms by using 905-nm high-power diode-laser assemblies

NASA Astrophysics Data System (ADS)

Leggio, Luca; Gallego, Daniel C.; Gawali, Sandeep Babu; Dadrasnia, Ehsan; Sánchez, Miguel; Rodríguez, Sergio; González, Marta; Carpintero, Guillermo; Osiński, Marek; Lamela, Horacio

2016-03-01

During the last two decades, optoacoustic imaging has been developed as a novel biomedical imaging technique based on the generation of ultrasound waves by means of laser light. In this work, we investigate the optoacoustic response from graphene-based solutions by using a compact and cost-effective system based on an assembly of several 905-nm pulsed high-power diode lasers coupled to a bundle of 200-μm diameter- core optical fibers. The coupled light is conveyed into a lens system and focused on an absorber consisting of graphene-based nanomaterials (graphene oxide, reduced graphene oxide, and reduced graphene-oxide/gold-nanoparticle hybrid, respectively) diluted in ethanol and hosted in slightly scattering optical phantoms. The high absorption of these graphene-based solutions suggests their potential future use in optoacoustic applications as contrast agents.

Design concepts using ring lasers for frequency stabilization

NASA Technical Reports Server (NTRS)

Mocker, H.

1967-01-01

Laser frequency stabilization methods are based on a frequency discriminant which generates an unambiguous deviation signal used for automatic stabilization. Closed-loop control stabilizes cavity length at a null point. Some systems have a stabilized ring laser using a piezoelectric dither and others use a Doppler gain tube.

Efficient TEA CO II-laser-based coating removal system

NASA Astrophysics Data System (ADS)

Prinsloo, F. J.; van Heerden, S. P.; Ronander, E.; Botha, L. R.

2007-05-01

A high power 1kW pulsed transversely excited atmospheric CO II laser that has been developed for the paint stripping of missiles was used to test paint stripping on several metallic and composite aircraft panels to determine the rate at which this laser could remove paint from aircraft.

Random noise can help to improve synchronization of excimer laser pulses.

PubMed

Mingesz, Róbert; Barna, Angéla; Gingl, Zoltán; Mellár, János

2016-02-01

Recently, we have reported on a compact microcontroller-based unit developed to accurately synchronize excimer laser pulses (Mingesz et al. 2012 Fluct. Noise Lett. 11, 1240007 (doi:10.1142/S021947751240007X)). We have shown that dithering based on random jitter noise plus pseudorandom numbers can be used in the digital control system to radically reduce the long-term drift of the laser pulse from the trigger and to improve the accuracy of the synchronization. In this update paper, we present our new experimental results obtained by the use of the delay-controller unit to tune the timing of a KrF excimer laser as an addition to our previous numerical simulation results. The hardware was interfaced to the laser using optical signal paths in order to reduce sensitivity to electromagnetic interference and the control algorithm tested by simulations was applied in the experiments. We have found that the system is able to reduce the delay uncertainty very close to the theoretical limit and performs well in real applications. The simple, compact and flexible system is universal enough to also be used in various multidisciplinary applications.

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.

Method and apparatus for controlling carrier envelope phase

DOEpatents

Chang, Zenghu [Manhattan, KS; Li, Chengquan [Sunnyvale, CA; Moon, Eric [Manhattan, KS

2011-12-06

A chirped pulse amplification laser system. The system generally comprises a laser source, a pulse modification apparatus including first and second pulse modification elements separated by a separation distance, a positioning element, a measurement device, and a feedback controller. The laser source is operable to generate a laser pulse and the pulse modification apparatus operable to modify at least a portion of the laser pulse. The positioning element is operable to reposition at least a portion of the pulse modification apparatus to vary the separation distance. The measurement device is operable to measure the carrier envelope phase of the generated laser pulse and the feedback controller is operable to control the positioning element based on the measured carrier envelope phase to vary the separation distance of the pulse modification elements and control the carrier envelope phase of laser pulses generated by the laser source.

Research on airborne infrared leakage detection of natural gas pipeline

NASA Astrophysics Data System (ADS)

Tan, Dongjie; Xu, Bin; Xu, Xu; Wang, Hongchao; Yu, Dongliang; Tian, Shengjie

2011-12-01

An airborne laser remote sensing technology is proposed to detect natural gas pipeline leakage in helicopter which carrying a detector, and the detector can detect a high spatial resolution of trace of methane on the ground. The principle of the airborne laser remote sensing system is based on tunable diode laser absorption spectroscopy (TDLAS). The system consists of an optical unit containing the laser, camera, helicopter mount, electronic unit with DGPS antenna, a notebook computer and a pilot monitor. And the system is mounted on a helicopter. The principle and the architecture of the airborne laser remote sensing system are presented. Field test experiments are carried out on West-East Natural Gas Pipeline of China, and the results show that airborne detection method is suitable for detecting gas leak of pipeline on plain, desert, hills but unfit for the area with large altitude diversification.

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.

Velocimetry using scintillation of a laser beam for a laser-based gas-flux monitor

NASA Astrophysics Data System (ADS)

Kagawa, Naoki; Wada, Osami; Koga, Ryuji

1999-05-01

This paper describes a velocimetry system using scintillation of a laser-beam with spatial filters based on sensor arrays for a laser- based gas flux monitor. In the eddy correlation method, gas flux is obtained by mutual relation between the gas density and the flow velocity. The velocimetry system is developed to support the flow velocity monitor portion of the laser-based gas flux monitor with a long span for measurement. In order to sense not only the flow velocity but also the flow direction, two photo diode arrays are arranged with difference of a quarter period of the weighting function between them; the two output signals from the sensor arrays have phase difference of either (pi) /2 or -(pi) /2 depending on the sense of flow direction. In order to obtain the flow velocity and the flow direction instantly, an electronic apparatus built by the authors extracts frequency and phase from crude outputs of the pair of sensors. A feasibility of the velocimetry was confirmed indoors by measurement of the flow- velocity vector of the convection. Measured flow-velocity vector of the upward flow agreed comparatively with results of an ultrasonic anemometer.

Detection of multiple chemicals based on external cavity quantum cascade laser spectroscopy

NASA Astrophysics Data System (ADS)

Sun, Juan; Ding, Junya; Liu, Ningwu; Yang, Guangxiang; Li, Jingsong

2018-02-01

A laser spectroscopy system based on a broadband tunable external cavity quantum cascade laser (ECQCL) and a mini quartz crystal tuning fork (QCTF) detector was developed for standoff detection of volatile organic compounds (VOCs). The self-established spectral analysis model based on multiple algorithms for quantitative and qualitative analysis of VOC components (i.e. ethanol and acetone) was detailedly investigated in both closed cell and open path configurations. A good agreement was obtained between the experimentally observed spectra and the standard reference spectra. For open path detection of VOCs, the sensor system was demonstrated at a distance of 30 m. The preliminary laboratory results show that standoff detection of VOCs at a distance of over 100 m is very promising.

An Overview of Communications Technology and Development Efforts for 2015 SBIR Phase I

NASA Technical Reports Server (NTRS)

Nguyen, Hung D.; Steele, Gynelle C.

2017-01-01

This report highlights innovative SBIR 2015 Phase I projects specifically addressing areas in Communications Technology and Development which is one of six core competencies at NASA Glenn Research Center. There are fifteen technologies featured with emphasis on a wide spectrum of applications such as novel solid state lasers for space-based water vapor dial; wide temperature, high voltage and energy density capacitors for aerospace exploration; instrument for airborne measurement of carbonyl sulfide; high-power tunable seed laser for methane Lidar transmitter; ROC-rib deployable ka-band antenna for nanosatellites; a SIC-based microcontroller for high-temperature in-situ instruments and systems; improved yield, performance and reliability of high-actuator-count deformable mirrors; embedded multifunctional optical sensor system; switching electronics for space-based telescopes with advanced AO systems; integrated miniature DBR laser module for Lidar instruments; and much more. Each article in this booklet describes an innovation, technical objective, and highlights NASA commercial and industrial applications. space-based water vapor dial; wide temperature, high voltage and energy density capacitors foraerospace exploration; instrument for airborne measurement of carbonyl sulfide; high-power tunable seed laser formethane Lidar transmitter; ROC-rib deployable ka-band antenna for nanosatellites.

Continuous in-situ methane measurements at paddy fields in a rural area of India with poor electric infrastructure, using a low-cost instrument based on open-path near-IR laser absorption spectroscopy

NASA Astrophysics Data System (ADS)

Hidemori, T.; Matsumi, Y.; Nakayama, T.; Kawasaki, M.; Sasago, H.; Takahashi, K.; Imasu, R.; Takeuchi, W.; Adachi, M.; Machida, T.; Terao, Y.; Nomura, S.; Dhaka, S. K.; Singh, J.

2015-12-01

In southeast and south Asia, the previous satellite observations suggest that the methane emission from rice paddies is significant and important source of methane during rainy season. Since it is difficult to measure methane stably and continuously at rural areas such as the paddy fields in terms of infrastructures and maintenances, there are large uncertainties in quantitative estimation of methane emission in these areas and there are needs for more certification between satellite and ground based measurements. To measure methane concentrations continuously at difficult situations such as the center of paddy fields　and wetlands, we developed the continuous in-situ measurement system, not to look for your lost keys under the streetlight. The methane gas sensor is used an open-path laser based measurement instrument (LaserMethane, ANRITSU CORPORATION), which can quickly and selectively detect average methane concentrations on the optical path of the laser beam. The developed system has the power supply and telecommunication system to run the laser gas sensor in rural areas with poor electricity infrastructure.The methane measurement system was installed at paddy fields of Sonepat, Haryana on the north of Delhi in India and has been operated from the end of 2014. The air sampling along with our measurement has been carried out once a week during daytime to calibrate the laser instrument. We found that the seasonal variation of methane concentrations was different from the satellite observations and there were significant diurnal variations, which it was difficult to detect from occasional air samplings. We will present details of the measurement system and recent results of continuous methane measurements in India.

Development of a Fiber Laser with Independently Adjustable Properties for Optical Resolution Photoacoustic Microscopy.

PubMed

Aytac-Kipergil, Esra; Demirkiran, Aytac; Uluc, Nasire; Yavas, Seydi; Kayikcioglu, Tunc; Salman, Sarper; Karamuk, Sohret Gorkem; Ilday, Fatih Omer; Unlu, Mehmet Burcin

2016-12-08

Photoacoustic imaging is based on the detection of generated acoustic waves through thermal expansion of tissue illuminated by short laser pulses. Fiber lasers as an excitation source for photoacoustic imaging have recently been preferred for their high repetition frequencies. Here, we report a unique fiber laser developed specifically for multiwavelength photoacoustic microscopy system. The laser is custom-made for maximum flexibility in adjustment of its parameters; pulse duration (5-10 ns), pulse energy (up to 10 μJ) and repetition frequency (up to 1 MHz) independently from each other and covers a broad spectral region from 450 to 1100 nm and also can emit wavelengths of 532, 355, and 266 nm. The laser system consists of a master oscillator power amplifier, seeding two stages; supercontinuum and harmonic generation units. The laser is outstanding since the oscillator, amplifier and supercontinuum generation parts are all-fiber integrated with custom-developed electronics and software. To demonstrate the feasibility of the system, the images of several elements of standardized resolution test chart are acquired at multiple wavelengths. The lateral resolution of optical resolution photoacoustic microscopy system is determined as 2.68 μm. The developed system may pave the way for spectroscopic photoacoustic microscopy applications via widely tunable fiber laser technologies.

Development of a Fiber Laser with Independently Adjustable Properties for Optical Resolution Photoacoustic Microscopy

PubMed Central

Aytac-Kipergil, Esra; Demirkiran, Aytac; Uluc, Nasire; Yavas, Seydi; Kayikcioglu, Tunc; Salman, Sarper; Karamuk, Sohret Gorkem; Ilday, Fatih Omer; Unlu, Mehmet Burcin

2016-01-01

Photoacoustic imaging is based on the detection of generated acoustic waves through thermal expansion of tissue illuminated by short laser pulses. Fiber lasers as an excitation source for photoacoustic imaging have recently been preferred for their high repetition frequencies. Here, we report a unique fiber laser developed specifically for multiwavelength photoacoustic microscopy system. The laser is custom-made for maximum flexibility in adjustment of its parameters; pulse duration (5–10 ns), pulse energy (up to 10 μJ) and repetition frequency (up to 1 MHz) independently from each other and covers a broad spectral region from 450 to 1100 nm and also can emit wavelengths of 532, 355, and 266 nm. The laser system consists of a master oscillator power amplifier, seeding two stages; supercontinuum and harmonic generation units. The laser is outstanding since the oscillator, amplifier and supercontinuum generation parts are all-fiber integrated with custom-developed electronics and software. To demonstrate the feasibility of the system, the images of several elements of standardized resolution test chart are acquired at multiple wavelengths. The lateral resolution of optical resolution photoacoustic microscopy system is determined as 2.68 μm. The developed system may pave the way for spectroscopic photoacoustic microscopy applications via widely tunable fiber laser technologies. PMID:27929049

High power laser source for atom cooling based on reliable telecoms technology with all fibre frequency stabilisation

NASA Astrophysics Data System (ADS)

Legg, Thomas; Farries, Mark

2017-02-01

Cold atom interferometers are emerging as important tools for metrology. Designed into gravimeters they can measure extremely small changes in the local gravitational field strength and be used for underground surveying to detect buried utilities, mineshafts and sinkholes prior to civil works. To create a cold atom interferometer narrow linewidth, frequency stabilised lasers are required to cool the atoms and to setup and measure the atom interferometer. These lasers are commonly either GaAs diodes, Ti Sapphire lasers or frequency doubled InGaAsP diodes and fibre lasers. The InGaAsP DFB lasers are attractive because they are very reliable, mass-produced, frequency controlled by injection current and simply amplified to high powers with fibre amplifiers. In this paper a laser system suitable for Rb atom cooling, based on a 1560nm DFB laser and erbium doped fibre amplifier, is described. The laser output is frequency doubled with fibre coupled periodically poled LiNbO3 to a wavelength of 780nm. The output power exceeds 1 W at 780nm. The laser is stabilised at 1560nm against a fibre Bragg resonator that is passively temperature compensated. Frequency tuning over a range of 1 GHz is achieved by locking the laser to sidebands of the resonator that are generated by a phase modulator. This laser design is attractive for field deployable rugged systems because it uses all fibre coupled components with long term proven reliability.

An Accurate Non-Cooperative Method for Measuring Textureless Spherical Target Based on Calibrated Lasers.

PubMed

Wang, Fei; Dong, Hang; Chen, Yanan; Zheng, Nanning

2016-12-09

Strong demands for accurate non-cooperative target measurement have been arising recently for the tasks of assembling and capturing. Spherical objects are one of the most common targets in these applications. However, the performance of the traditional vision-based reconstruction method was limited for practical use when handling poorly-textured targets. In this paper, we propose a novel multi-sensor fusion system for measuring and reconstructing textureless non-cooperative spherical targets. Our system consists of four simple lasers and a visual camera. This paper presents a complete framework of estimating the geometric parameters of textureless spherical targets: (1) an approach to calibrate the extrinsic parameters between a camera and simple lasers; and (2) a method to reconstruct the 3D position of the laser spots on the target surface and achieve the refined results via an optimized scheme. The experiment results show that our proposed calibration method can obtain a fine calibration result, which is comparable to the state-of-the-art LRF-based methods, and our calibrated system can estimate the geometric parameters with high accuracy in real time.

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.

kW picosecond thin-disk regenerative amplifier

NASA Astrophysics Data System (ADS)

Michel, Knut; Wandt, Christoph; Klingebiel, Sandro; Schultze, Marcel; Prinz, Stephan; Teisset, Catherine Y.; Stark, Sebastian; Grebing, Christian; Bessing, Robert; Herzig, Tobias; Häfner, Matthias; Budnicki, Aleksander; Sutter, Dirk; Metzger, Thomas

2018-02-01

TRUMPF Scientific Lasers provides ultrafast laser sources for the scientific community with high pulse energies and high average power. All systems are based on the industrialized TRUMPF thin-disk technology. Regenerative amplifiers systems with multi-millijoule pulses, kilohertz repetition rates and picosecond pulse durations are available. Record values of 220mJ at 1kHz could be demonstrated originally developed for pumping optical parametric amplifiers. The ultimate goal is to combine high energies, <100mJ per pulse, with average powers of several hundred watts to a kilowatt. Based on a regenerative amplifier containing two Ytterbium doped thin-disks operated at ambient temperature pulses with picosecond duration and more than 100mJ could be generated at a repetition rate of 10kHz reaching 1kW of average output power. This system is designed to operate at different repetition rates from 100kHz down to 5kHz so that even higher pulse energies can be reached. This type of ultrafast sources uncover new application fields in science. Laser based lightning rods, X-ray lasers and Compton backscatter sources are among them.

An Accurate Non-Cooperative Method for Measuring Textureless Spherical Target Based on Calibrated Lasers

PubMed Central

Wang, Fei; Dong, Hang; Chen, Yanan; Zheng, Nanning

2016-01-01

Strong demands for accurate non-cooperative target measurement have been arising recently for the tasks of assembling and capturing. Spherical objects are one of the most common targets in these applications. However, the performance of the traditional vision-based reconstruction method was limited for practical use when handling poorly-textured targets. In this paper, we propose a novel multi-sensor fusion system for measuring and reconstructing textureless non-cooperative spherical targets. Our system consists of four simple lasers and a visual camera. This paper presents a complete framework of estimating the geometric parameters of textureless spherical targets: (1) an approach to calibrate the extrinsic parameters between a camera and simple lasers; and (2) a method to reconstruct the 3D position of the laser spots on the target surface and achieve the refined results via an optimized scheme. The experiment results show that our proposed calibration method can obtain a fine calibration result, which is comparable to the state-of-the-art LRF-based methods, and our calibrated system can estimate the geometric parameters with high accuracy in real time. PMID:27941705

Assessment of laser tracking and data transfer for underwater optical communications

NASA Astrophysics Data System (ADS)

Watson, Malcolm A.; Blanchard, Paul M.; Stace, Chris; Bhogul, Priya K.; White, Henry J.; Kelly, Anthony E.; Watson, Scott; Valyrakis, Manousos; Najda, Stephen P.; Marona, Lucja; Perlin, Piotr

2014-10-01

We report on an investigation into optical alignment and tracking for high bandwidth, laser-based underwater optical communication links. Link acquisition approaches (including scanning of narrow laser beams versus a wide-angle `beacon' approach) for different underwater laser-based communications scenarios are discussed. An underwater laserbased tracking system was tested in a large water flume facility using water whose scattering properties resembled that of a turbid coastal or harbour region. The lasers used were state-of-the-art, temperature-controlled, high modulation bandwidth gallium nitride (GaN) devices. These operate at blue wavelengths and can achieve powers up to ~100 mW. The tracking performance and characteristics of the system were studied as the light-scattering properties of the water were increased using commercial antacid (Maalox) solution, and the results are reported here. Optical tracking is expected to be possible even in high scattering water environments, assuming better components are developed commercially; in particular, more sensitive detector arrays. High speed data transmission using underwater optical links, based on blue light sources, is also reported.

Characterization of a quantum cascade laser-based emissivity monitor for CORSAIR

NASA Astrophysics Data System (ADS)

Lwin, Maung; Wojcik, Michael; Latvakoski, Harri; Scott, Deron; Watson, Mike; Marchant, Alan; Topham, Shane; Mlynczak, Martin

2011-06-01

Continuous improvements of quantum cascade laser (QCL) technology have extended the applications in environmental trace gas monitoring, mid-infrared spectroscopy in medicine and life science, law enforcement and homeland security and satellite sensor systems. We present the QCL based emissivity monitor for the CORSAIR blackbody. The emissivity of the blackbody was designed to be better than 0.9999 for the spectral range between 5 to 50μm. To actively monitor changes in blackbody emissivity we employ a QCL-based infrared illumination source. The illumination source consisted of a QCL and thermoelectric cooler (TEC) unit mounted on a copper fixture. The stability of the QCL was measured for 30, 60, and 90s operation time at 1.5A driving current. The temperature distribution along the laser mounting fixture and time dependent system heat dispersion were analyzed. The results were compared to radiative and conductive heat transfer models to define the potential laser operating time and required waiting time to return to initial temperature of the laser mount. The observed cooling behaviour is consistent with a primarily conductive heat transfer mechanism.

Communication scheme using a hyperchaotic semiconductor laser model: Chaos shift key revisited

NASA Astrophysics Data System (ADS)

Fataf, N. A. A.; Palit, Sanjay Kumar; Mukherjee, Sayan; Said, M. R. M.; Son, Doan Hoai; Banerjee, Santo

2017-11-01

Based on the Maxwell-Bloch equations, we considered a five-dimensional ODE system, describing the dynamics of a semiconductor laser. The system has rich dynamics with multi-periodic, chaotic and hyperchaotic states. In this analysis, we have investigated the hyperchaotic nature of the aforesaid model and proposed a communication scheme, the generalized form of chaos shift keys, where the coupled systems do not need to be in the synchronized state. The results are implemented with the hyperchaotic laser model followed by a comprehensive security analysis.

Control system of an excitation power supply for fast axial flow CO2 lasersupda

NASA Astrophysics Data System (ADS)

Li, Bo; Jia, Xinting; Yuan, Hao; Gao, Yuhu; Wang, Youqing

2009-08-01

A switching power control system of fast axial flow CO2 lasers based on DSP is presented. The key techniques are described in detail, include the control principle, realization method and program design. The experiment showed that the system make the laser discharge stably and work in multi-mode. The discharge current can be adjusted from 3mA to 85mA continuously. 20-2000Hz frequency, 0-100% duty cycle laser pulse is achieved. The power supply can improve the processing efficiency and quality.

Development of multi-touch panel backlight system

NASA Astrophysics Data System (ADS)

Chomiczewski, J.; Długosz, M.; Godlewski, G.; Kochanowicz, M.

2013-10-01

The paper presents design, simulation analysis, and measurements of parameters of optical multi touch panel backlight system. Comparison of optical technology with commercially available solutions was also performed. The numerical simulation of laser based backlight system was made. The influence of the laser power, beam divergence, and placing reflective surfaces on the uniformity of illumination were examined. Optimal illumination system was used for further studies.

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.

Lower-free tropospheric ozone dial measurements over Athens, Greece

NASA Astrophysics Data System (ADS)

Mytilinaios, Michail; Papayannis, Alexandros; Tsaknakis, Georgios

2018-04-01

A compact ozone differential absorption lidar (DIAL) was implemented at the Laboratory of Laser Remote Sensing of the National Technical University of Athens (NTUA), in Athens, Greece. The DIAL system is based on a Nd:YAG laser emitting at 266 nm. A high-pressure Raman cell, filled with D2, was used to generate the λON and λOFF laser wavelength pairs (i.e., 266-289 nm and 289-316 nm, respectively) based on the Stimulated Raman Scattering (SRS) effect. The system was run during daytime and nighttime conditions to obtain the vertical profile of tropospheric ozone in the Planetary Boundary Layer (PBL) and the adjacent free troposphere.

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.

Nineteenth International Laser Radar Conference. Part 2

NASA Technical Reports Server (NTRS)

Singh, Upendra N. (Editor); Ismail, Syed (Editor); Schwemmer, Geary K. (Editor)

1998-01-01

This publication contains extended abstracts of papers presented at the Nineteenth International Laser Radar Conference, held at Annapolis, Maryland, July 6-10, 1998; 260 papers were presented in both oral and poster sessions. The topics of the conference sessions were Aerosol Clouds, Multiple Scattering; Tropospheric Profiling, Stratospheric/Mesospheric Profiling; Wind Profiling; New Lidar Technology and Techniques; Lidar Applications, Including Altimetry and Marine; Space and Future Lidar; and Lidar Commercialization/Eye Safety. This conference reflects the breadth of research activities being conducted in the lidar field. These abstracts address subjects from lidar-based atmospheric investigations, development of new lasers and lidar system technology, and current and future space-based lidar systems.

Nineteenth International Laser Radar Conference. Part 1

NASA Technical Reports Server (NTRS)

Singh, Upendra N. (Editor); Ismail, Syed (Editor); Schwemmer, Geary K. (Editor)

1998-01-01

This publication contains extended abstracts of papers presented at the Nineteenth International Laser Radar Conference, held at Annapolis, Maryland, July 6-10, 1998; 260 papers were presented in both oral and poster sessions. The topics of the conference sessions were Aerosol Clouds, Multiple Scattering; Tropospheric Profiling; Stratospheric/Mesospheric Profiling; Wind Profiling; New Lidar Technology and Techniques; Lidar Applications, including Altimetry and Marine; Space and Future Lidar; and Lidar Commercialization/Eye Safety. This conference reflects the breadth of research activities being conducted in the lidar field. These abstracts address subjects from lidar-based atmospheric investigations, development of new lasers and lidar system technology, and current and future space-based lidar systems.

Laser system for identification, tracking, and control of flying insects

USDA-ARS?s Scientific Manuscript database

Flying insects are common vectors for transmission of pathogens and inflict significant harm on humans in large parts of the developing world. Besides the direct impact to humans, these pathogens also cause harm to crops and result in agricultural losses. Here, we present a laser-based system that c...

TOPSAT: Global space topographic mission

NASA Technical Reports Server (NTRS)

Vetrella, Sergio

1993-01-01

Viewgraphs on TOPSAT Global Space Topographic Mission are presented. Topics covered include: polar region applications; terrestrial ecosystem applications; stereo electro-optical sensors; space-based stereoscopic missions; optical stereo approach; radar interferometry; along track interferometry; TOPSAT-VISTA system approach; ISARA system approach; topographic mapping laser altimeter; and role of multi-beam laser altimeter.

Two-Photon Raman Gain in a Laser Driven Potassium Vapor

DTIC Science & Technology

1996-02-01

between light and matter becomes highly nonlinear and the light and matter strongly couple, the systems become much more difficult to understand both...theoretically and experimentally. One example of a strongly coupled, highly nonlinear system is the two-photon laser that is based on the two-photon

Laser Pointers: Low-Cost, Low-Tech Innovative, Interactive Instruction Tool

ERIC Educational Resources Information Center

Zdravkovska, Nevenka; Cech, Maureen; Beygo, Pinar; Kackley, Bob

2010-01-01

This paper discusses the use of laser pointers at the Engineering and Physical Sciences Library, University of Maryland, College Park, as a personal response system (PRS) tool to encourage student engagement in and interactivity with one-shot, lecture-based information literacy sessions. Unlike more sophisticated personal response systems like…

A portable lidar using a diode-pumped YAG laser

NASA Technical Reports Server (NTRS)

Takeuchi, N.; Okumura, H.; Sugita, T.; Matsumoto, H.; Yamaguchi, S.

1992-01-01

A Mie lidar system is technically established and is used for monitoring air pollution, stratospheric and boundary layer aerosol distribution, plume dispersion, visibility, and the study of atmospheric structure and cloud physics. However, a lidar system is not widely used because of its cumbersome handling and unwieldy portability. Although the author developed a laser diode lidar system based on RM-CW technique, it has a limit of measurement distance. Here we report the development of an all solid Mie lidar system using a diode-pumped Nd:YAG laser and a Si-APD detector. This was constructed as a prototype of a handy lidar system.

System for the design, manufacture, and testing of custom lenses with known amounts of high-order aberrations.

PubMed

Chernyak, Dimitri A; Campbell, Charles E

2003-11-01

Now that excimer laser systems can be programmed to correct complex aberrations of the eye on the basis of wave-front measurements, a method is needed to test the accuracy of the system from measurement through treatment. A closed-loop test method was developed to ensure that treatment plans generated by a wavefront measuring system were accurately transferred to and executed by the excimer laser. A surface was analytically defined, and a Shack-Hartmann-based wave-front system was used to formulate a treatment plan, which was downloaded to an excimer laser system. A plastic lens was ablated by the laser and then returned to the wave-front device, where it was measured and compared with the analytically defined wave-front surface. The two surfaces agreed up to 6th-order Zernike terms, validating the accuracy of the system.

Generation of 1-J bursts with picosecond pulses from Perla B thin-disk laser system

NASA Astrophysics Data System (ADS)

Chyla, Michal; Nagisetty, Siva S.; Severova, Patricie; Zhou, Huang; Smrz, Martin; Endo, Akira; Mocek, Tomas

2018-02-01

In many fields of modern physics and industrial applications high-average power pulsed diode-pumped solid-state lasers are essential. Scaling of these lasers towards higher pulse energies is often limited by the onset of thermal effects which are determined by the average power. In this paper we would like to propose a way of increasing the pulse energies by operating the PERLA B laser system in 100 Hz burst mode with 1 ms burst duration and intra-burst repetition rate of 10 kHz. The CPA-based system incorporates fiber front-end, regenerative amplifier and the multipass amplifier followed by the booster amplifier and <2ps compressor.

Visualization of the influence of the air conditioning system to the high-power laser beam quality with the modulation coherent imaging method.

PubMed

Tao, Hua; Veetil, Suhas P; Pan, Xingchen; Liu, Cheng; Zhu, Jianqiang

2015-08-01

Air conditioning systems can lead to dynamic phase change in the laser beams of high-power laser facilities for the inertial confinement fusion, and this kind of phase change cannot be measured by most of the commonly employed Hartmann wavefront sensor or interferometry due to some uncontrollable factors, such as too large laser beam diameters and the limited space of the facility. It is demonstrated that this problem can be solved using a scheme based on modulation coherent imaging, and thus the influence of the air conditioning system on the performance of the high-power facility can be evaluated directly.

Target Assembly to Check Boresight Alignment of Active Sensors

NASA Technical Reports Server (NTRS)

Ramos-Izquierdo, Luis; Scott, V. Stanley; Riris, Haris; Cavanaugh, John; Liiva, Peter; Rodriguez, Michael

2011-01-01

A compact and portable target assembly (Fig. 1) has been developed to measure the boresite alignment of LRO's Lunar Orbiter Laser Altimeter (LOLA) instrument at the spacecraft level. The concept for this target assembly has evolved over many years with earlier versions used to test the Mars Observer Laser Altimeter (MOLA), the Geoscience Laser Altimeter System (GLAS), and the Mercury Laser Altimeter (MLA) space-based instruments.

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.

Towards femtosecond laser surgery guidance in the posterior eye: utilization of optical coherence tomography and adaptive optics for focus positioning and shaping

NASA Astrophysics Data System (ADS)

Krüger, Alexander; Hansen, Anja; Matthias, Ben; Ripken, Tammo

2014-02-01

Although fs-laser surgery is clinically established in the field of corneal flap cutting for laser in situ keratomileusis, surgery with fs-laser in the posterior part of the eye is impaired by focus degradation due to aberrations. Precise targeting and keeping of safety distance to the retina also relies on an intraoperative depth resolved imaging. We demonstrate a concept for image guided fs-laser surgery in the vitreous body combining adaptive optics (AO) for focus reshaping and optical coherence tomography (OCT) for focus position guidance. The setup of the laboratory system consist of an 800 nm fs-laser which is focused into a simple eye model via a closed loop adaptive optics system with Hartmann-Shack sensor and a deformable mirror to correct for wavefront aberrations. A spectral domain optical coherence tomography system is used to target phantom structures in the eye model. Both systems are set up to share the same scanner and focusing optics. The use of adaptive optics results in a lowered threshold energy for laser induced breakdown and an increased cutting precision. 3D OCT imaging of porcine retinal tissue prior and immediately after fs-laser cutting is also demonstrated. In the near future OCT and AO will be two essential assistive components in possible clinical systems for fs-laser based eye surgery beyond the cornea.

Free space broad-bandwidth tunable laser diode based on Littman configuration for 3D profile measurement

NASA Astrophysics Data System (ADS)

Shirazi, Muhammad Faizan; Kim, Pilun; Jeon, Mansik; Kim, Chang-Seok; Kim, Jeehyun

2018-05-01

We developed a tunable laser diode for an optical coherence tomography system that can perform three-dimensional profile measurement using an area scanning technique. The tunable laser diode is designed using an Eagleyard tunable laser diode with a galvano filter. The Littman free space configuration is used to demonstrate laser operation. The line- and bandwidths of this source are 0.27 nm (∼110 GHz) and 43 nm, respectively, at the center wavelength of 860 nm. The output power is 20 mW at an operating current of 150 mA. A step height target is imaged using a wide-area scanning system to show the measurement accuracy of the proposed tunable laser diode. A TEM grid is also imaged to measure the topography and thickness of the sample by proposed tunable laser diode.

Review on recent research progress on laser power measurement based on light pressure

NASA Astrophysics Data System (ADS)

Lai, WenChang; Zhou, Pu

2018-03-01

Accurate measuring the laser power is one of the most important issue to evaluate the performance of high power laser. For the time being, most of the demonstrated technique could be attributed to direct measuring route. Indirect measuring laser power based on light pressure, which has been under intensive investigation, has the advantages such as fast response, real-time measuring and high accuracy, compared with direct measuring route. In this paper, we will review several non-traditional methods based on light pressure to precisely measure the laser power proposed recently. The system setup, measuring principle and scaling methods would be introduced and analyzed in detail. We also compare the benefit and the drawback of these methods and analyze the uncertainties of the measurements.

High-energy laser activities at MBDA Germany

NASA Astrophysics Data System (ADS)

Mohring, Bernd; Dietrich, Stephan; Tassini, Leonardo; Protz, Rudolf; Geidek, Franz; Zoz, Jürgen

2013-05-01

At MBDA Germany a concept for a high-energy laser weapon system is investigated, which is based on existing industrial laser sources. Due to the enormous progress in the field of high-power fiber lasers, commercial industrial fiber lasers are now available delivering a nearly-diffraction limited beam quality with power levels of up to 10 kW. By using a geometric beam coupling scheme, a number of individual high-power fiber laser beams are combined together using one common beam director telescope. A total laser beam power of more than 100 kW can be achieved, which is sufficient for an operational laser weapon system. The individual beams from the different lasers are steered by servo-loops using fast tip-tilt mirrors. This principle enables the concentration of the total laser beam power at one common focal point on a distant target, also allowing fine tracking of target movements and first-order compensation of turbulence effects on laser beam propagation. The proposed beam combination concept was demonstrated by using different experimental set-ups. A number of experiments were performed successfully to investigate laser beam target interaction and target fine tracking, also at large distances and at moving targets. Content and results of these investigations are reported, which demonstrate the complete engagement sequence for a C-RAM scenario. This includes subsequent steps of target acquisition by radar and IR optics, followed by large angle coarse tracking, active fine tracking and destruction of the target by the laser system. This successful implementation of geometric beam combining is an important step for the realization of a laser weapon system in the near future.

An Automated Inner Dimensional Measurement System Based on a Laser Displacement Sensor for Long-Stepped Pipes

PubMed Central

Zhang, Fumin; Qu, Xinghua; Ouyang, Jianfei

2012-01-01

A novel measurement prototype based on a mobile vehicle that carries a laser scanning sensor is proposed. The prototype is intended for the automated measurement of the interior 3D geometry of large-diameter long-stepped pipes. The laser displacement sensor, which has a small measurement range, is mounted on an extended arm of known length. It is scanned to improve the measurement accuracy for large-sized pipes. A fixing mechanism based on two sections is designed to ensure that the stepped pipe is concentric with the axis of rotation of the system. Data are acquired in a cylindrical coordinate system and fitted in a circle to determine diameter. Systematic errors covering arm length, tilt, and offset errors are analyzed and calibrated. The proposed system is applied to sample parts and the results are discussed to verify its effectiveness. This technique measures a diameter of 600 mm with an uncertainty of 0.02 mm at a 95% confidence probability. A repeatability test is performed to examine precision, which is 1.1 μm. A laser tracker is used to verify the measurement accuracy of the system, which is evaluated as 9 μm within a diameter of 600 mm. PMID:22778615

Demonstration of sensitivity increase in mercury free-spin-precession magnetometers due to laser-based readout for neutron electric dipole moment searches

NASA Astrophysics Data System (ADS)

Ban, G.; Bison, G.; Bodek, K.; Daum, M.; Fertl, M.; Franke, B.; Grujić, Z. D.; Heil, W.; Horras, M.; Kasprzak, M.; Kermaidic, Y.; Kirch, K.; Koch, H.-C.; Komposch, S.; Kozela, A.; Krempel, J.; Lauss, B.; Lefort, T.; Mtchedlishvili, A.; Pignol, G.; Piegsa, F. M.; Prashanth, P.; Quéméner, G.; Rawlik, M.; Rebreyend, D.; Ries, D.; Roccia, S.; Rozpedzik, D.; Schmidt-Wellenburg, P.; Severijns, N.; Weis, A.; Wyszynski, G.; Zejma, J.; Zsigmond, G.

2018-07-01

We report on a laser based 199Hg co-magnetometer deployed in an experiment searching for a permanent electric dipole moment of the neutron. We demonstrate a more than five times increased signal to-noise-ratio in a direct comparison measurement with its 204Hg discharge bulb-based predecessor. An improved data model for the extraction of important system parameters such as the degrees of absorption and polarization is derived. Laser- and lamp-based data-sets can be consistently described by the improved model which permits to compare measurements using the two different light sources and to explain the increase in magnetometer performance. The laser-based magnetometer satisfies the magnetic field sensitivity requirements for the next generation nEDM experiments.

Process observation in fiber laser-based selective laser melting

NASA Astrophysics Data System (ADS)

Thombansen, Ulrich; Gatej, Alexander; Pereira, Milton

2015-01-01

The process observation in selective laser melting (SLM) focuses on observing the interaction point where the powder is processed. To provide process relevant information, signals have to be acquired that are resolved in both time and space. Especially in high-power SLM, where more than 1 kW of laser power is used, processing speeds of several meters per second are required for a high-quality processing results. Therefore, an implementation of a suitable process observation system has to acquire a large amount of spatially resolved data at low sampling speeds or it has to restrict the acquisition to a predefined area at a high sampling speed. In any case, it is vitally important to synchronously record the laser beam position and the acquired signal. This is a prerequisite that allows the recorded data become information. Today, most SLM systems employ f-theta lenses to focus the processing laser beam onto the powder bed. This report describes the drawbacks that result for process observation and suggests a variable retro-focus system which solves these issues. The beam quality of fiber lasers delivers the processing laser beam to the powder bed at relevant focus diameters, which is a key prerequisite for this solution to be viable. The optical train we present here couples the processing laser beam and the process observation coaxially, ensuring consistent alignment of interaction zone and observed area. With respect to signal processing, we have developed a solution that synchronously acquires signals from a pyrometer and the position of the laser beam by sampling the data with a field programmable gate array. The relevance of the acquired signals has been validated by the scanning of a sample filament. Experiments with grooved samples show a correlation between different powder thicknesses and the acquired signals at relevant processing parameters. This basic work takes a first step toward self-optimization of the manufacturing process in SLM. It enables the addition of cognitive functions to the manufacturing system to the extent that the system could track its own process. The results are based on analyzing and redesigning the optical train, in combination with a real-time signal acquisition system which provides a solution to certain technological barriers.

Controlling Second Harmonic Efficiency of Laser Beam Interactions

NASA Technical Reports Server (NTRS)

Barnes, Norman P. (Inventor); Walsh, Brian M. (Inventor); Reichle, Donald J. (Inventor)

2011-01-01

A method is provided for controlling second harmonic efficiency of laser beam interactions. A laser system generates two laser beams (e.g., a laser beam with two polarizations) for incidence on a nonlinear crystal having a preferred direction of propagation. Prior to incidence on the crystal, the beams are optically processed based on the crystal's beam separation characteristics to thereby control a position in the crystal along the preferred direction of propagation at which the beams interact.

APPLICATIONS OF LASERS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Laser system based on a commercial microwave oscillator with time compression of a microwave pump pulse

NASA Astrophysics Data System (ADS)

Arteev, M. S.; Vaulin, V. A.; Slinko, V. N.; Chumerin, P. Yu; Yushkov, Yu G.

1992-06-01

An analysis is made of the possibility of using a commercial microsecond microwave oscillator, supplemented by a device for time compression of microwave pulses, in pumping of industrial lasers with a high efficiency of conversion of the pump source energy into laser radiation. The results are reported of preliminary experiments on the commissioning of an excimer XeCl laser.

Joining Pipe with the Hybrid Laser-GMAW Process: Weld Test Results and Cost Analysis

DTIC Science & Technology

2006-06-01

Recent work investigating the poten- tial benefit of applying this technology to a shipyard pipe shop suggests that signifi- cant cost savings may be...arc-based joining processes. With recent advances in com- mercial laser technology , laser suppliers can now deliver dramatically higher power systems...reasons, shipyards in the U.S. are showing growing interest in hybrid laser-GMA welding technology . Hybrid Laser-GMA for Joining Pipe Welding of pipe

System Model for MEMS based Laser Ultrasonic Receiver

NASA Technical Reports Server (NTRS)

Wilson, William C.

2002-01-01

A need has been identified for more advanced nondestructive Evaluation technologies for assuring the integrity of airframe structures, wiring, etc. Laser ultrasonic inspection instruments have been shown to detect flaws in structures. However, these instruments are generally too bulky to be used in the confined spaces that are typical of aerospace vehicles. Microsystems technology is one key to reducing the size of current instruments and enabling increased inspection coverage in areas that were previously inaccessible due to instrument size and weight. This paper investigates the system modeling of a Micro OptoElectroMechanical System (MOEMS) based laser ultrasonic receiver. The system model is constructed in software using MATLAB s dynamical simulator, Simulink. The optical components are modeled using geometrical matrix methods and include some image processing. The system model includes a test bench which simulates input stimuli and models the behavior of the material under test.

Laser-induced photo emission detection: data acquisition based on light intensity counting

NASA Astrophysics Data System (ADS)

Yulianto, N.; Yudasari, N.; Putri, K. Y.

2017-04-01

Laser Induced Breakdown Detection (LIBD) is one of the quantification techniques for colloids. There are two ways of detection in LIBD: optical detection and acoustic detection. LIBD is based on the detection of plasma emission due to the interaction between particle and laser beam. In this research, the changing of light intensity during plasma formations was detected by a photodiode sensor. A photo emission data acquisition system was built to collect and transform them into digital counts. The real-time system used data acquisition device National Instrument DAQ 6009 and LABVIEW software. The system has been tested on distilled water and tap water samples. The result showed 99.8% accuracy by using counting technique in comparison to the acoustic detection with sample rate of 10 Hz, thus the acquisition system can be applied as an alternative method to the existing LIBD acquisition system.

Nd:YAG development for spaceborne laser ranging system

NASA Technical Reports Server (NTRS)

Harper, L. L.; Logan, K. E.; Williams, R. H.; Stevens, D. A.

1979-01-01

The results of the development of a unique modelocked laser device to be utilized in future NASA space-based, ultraprecision laser ranger systems are summarized. The engineering breadboard constructed proved the feasibility of the pump-pulsed, actively modelocked, PTM Q-switched Nd:YAG laser concept for the generation of subnanosecond pulses suitable for ultra-precision ranging. The laser breadboard also included a double-pass Nd:YAG amplifier and provision for a Type II KD*P frequency doubler. The specific technical accomplishment was the generation of single 150 psec, 20-mJ pulses at 10 pps at a wavelength of 1.064 micrometers with 25 dB suppression of pre-and post-pulses.

A Framework Based on Reference Data with Superordinate Accuracy for the Quality Analysis of Terrestrial Laser Scanning-Based Multi-Sensor-Systems.

PubMed

Stenz, Ulrich; Hartmann, Jens; Paffenholz, Jens-André; Neumann, Ingo

2017-08-16

Terrestrial laser scanning (TLS) is an efficient solution to collect large-scale data. The efficiency can be increased by combining TLS with additional sensors in a TLS-based multi-sensor-system (MSS). The uncertainty of scanned points is not homogenous and depends on many different influencing factors. These include the sensor properties, referencing, scan geometry (e.g., distance and angle of incidence), environmental conditions (e.g., atmospheric conditions) and the scanned object (e.g., material, color and reflectance, etc.). The paper presents methods, infrastructure and results for the validation of the suitability of TLS and TLS-based MSS. Main aspects are the backward modelling of the uncertainty on the basis of reference data (e.g., point clouds) with superordinate accuracy and the appropriation of a suitable environment/infrastructure (e.g., the calibration process of the targets for the registration of laser scanner and laser tracker data in a common coordinate system with high accuracy) In this context superordinate accuracy means that the accuracy of the acquired reference data is better by a factor of 10 than the data of the validated TLS and TLS-based MSS. These aspects play an important role in engineering geodesy, where the aimed accuracy lies in a range of a few mm or less.

Spectrally high performing quantum cascade lasers

NASA Astrophysics Data System (ADS)

Toor, Fatima

Quantum cascade (QC) lasers are versatile semiconductor light sources that can be engineered to emit light of almost any wavelength in the mid- to far-infrared (IR) and terahertz region from 3 to 300 mum [1-5]. Furthermore QC laser technology in the mid-IR range has great potential for applications in environmental, medical and industrial trace gas sensing [6-10] since several chemical vapors have strong rovibrational frequencies in this range and are uniquely identifiable by their absorption spectra through optical probing of absorption and transmission. Therefore, having a wide range of mid-IR wavelengths in a single QC laser source would greatly increase the specificity of QC laser-based spectroscopic systems, and also make them more compact and field deployable. This thesis presents work on several different approaches to multi-wavelength QC laser sources that take advantage of band-structure engineering and the uni-polar nature of QC lasers. Also, since for chemical sensing, lasers with narrow linewidth are needed, work is presented on a single mode distributed feedback (DFB) QC laser. First, a compact four-wavelength QC laser source, which is based on a 2-by-2 module design, with two waveguides having QC laser stacks for two different emission wavelengths each, one with 7.0 mum/11.2 mum, and the other with 8.7 mum/12.0 mum is presented. This is the first design of a four-wavelength QC laser source with widely different emission wavelengths that uses minimal optics and electronics. Second, since there are still several unknown factors that affect QC laser performance, results on a first ever study conducted to determine the effects of waveguide side-wall roughness on QC laser performance using the two-wavelength waveguides is presented. The results are consistent with Rayleigh scattering effects in the waveguides, with roughness effecting shorter wavelengths more than longer wavelengths. Third, a versatile time-multiplexed multi-wavelength QC laser system that emits at lambda = 10.8 mum for positive and lambda = 8.6 mum for negative polarity current with microsecond time delay is presented. Such a system is the first demonstration of a time and wavelength multiplexed system that uses a single QC laser. Fourth, work on the design and fabrication of a single-mode distributed feedback (DFB) QC laser emitting at lambda ≈ 7.7 mum to be used in a QC laser based photoacoustic sensor is presented. The DFB QC laser had a temperature tuning co-efficient of 0.45 nm/K for a temperature range of 80 K to 320 K, and a side mode suppression ratio of greater than 30 dB. Finally, study on the lateral mode patterns of wide ridge QC lasers is presented. The results include the observation of degenerate and non-degenerate lateral modes in wide ridge QC lasers emitting at lambda ≈ 5.0 mum. This study was conducted with the end goal of using wide ridge QC lasers in a novel technique to spatiospectrally combine multiple transverse modes to obtain an ultra high power single spot QC laser beam.

Laser-Based Monitoring of CH4, CO2, NH3, and H2S in Animal Farming—System Characterization and Initial Demonstration

PubMed Central

Jaworski, Piotr; Nikodem, Michał

2018-01-01

In this paper, we present a system for sequential detection of multiple gases using laser-based wavelength modulation spectroscopy (WMS) method combined with a Herriot-type multi-pass cell. Concentration of hydrogen sulfide (H2S), methane (CH4), carbon dioxide (CO2), and ammonia (NH3) are retrieved using three distributed feedback laser diodes operating at 1574.5 nm (H2S and CO2), 1651 nm (CH4), and 1531 nm (NH3). Careful adjustment of system parameters allows for H2S sensing at single parts-per-million by volume (ppmv) level with strongly reduced interference from adjacent CO2 transitions even at atmospheric pressure. System characterization in laboratory conditions is presented and the results from initial tests in real-world application are demonstrated. PMID:29425175

Recycling of laser and plasma radiation energy for enhancement of extreme ultraviolet sources for nanolithography

NASA Astrophysics Data System (ADS)

Sizyuk, V.; Sizyuk, T.; Hassanein, A.; Johnson, K.

2018-01-01

We have developed comprehensive integrated models for detailed simulation of laser-produced plasma (LPP) and laser/target interaction, with potential recycling of the escaping laser and out-of-band plasma radiation. Recycling, i.e., returning the escaping laser and plasma radiation to the extreme ultraviolet (EUV) generation region using retroreflective mirrors, has the potential of increasing the EUV conversion efficiency (CE) by up to 60% according to our simulations. This would result in significantly reduced power consumption and/or increased EUV output. Based on our recently developed models, our High Energy Interaction with General Heterogeneous Target Systems (HEIGHTS) computer simulation package was upgraded for LPP devices to include various radiation recycling regimes and to estimate the potential CE enhancement. The upgraded HEIGHTS was used to study recycling of both laser and plasma-generated radiation and to predict possible gains in conversion efficiency compared to no-recycling LPP devices when using droplets of tin target. We considered three versions of the LPP system including a single CO2 laser, a single Nd:YAG laser, and a dual-pulse device combining both laser systems. The gains in generating EUV energy were predicted and compared for these systems. Overall, laser and radiation energy recycling showed the potential for significant enhancement in source efficiency of up to 60% for the dual-pulse system. Significantly higher CE gains might be possible with optimization of the pre-pulse and main pulse parameters and source size.

Compact CH 4 sensor system based on a continuous-wave, low power consumption, room temperature interband cascade laser

DOE PAGES

Dong, Lei; Li, Chunguang; Sanchez, Nancy P.; ...

2016-01-05

A tunable diode laser absorption spectroscopy-based methane sensor, employing a dense-pattern multi-pass gas cell and a 3.3 µm, CW, DFB, room temperature interband cascade laser (ICL), is reported. The optical integration based on an advanced folded optical path design and an efficient ICL control system with appropriate electrical power management resulted in a CH 4 sensor with a small footprint (32 x 20 x 17 cm 3) and low-power consumption (6 W). Polynomial and least-squares fit algorithms are employed to remove the baseline of the spectral scan and retrieve CH 4 concentrations, respectively. An Allan-Werle deviation analysis shows that themore » measurement precision can reach 1.4 ppb for a 60 s averaging time. Continuous measurements covering a seven-day period were performed to demonstrate the stability and robustness of the reported CH 4 sensor system.« less

Compact CH 4 sensor system based on a continuous-wave, low power consumption, room temperature interband cascade laser

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

Dong, Lei; Li, Chunguang; Sanchez, Nancy P.

A tunable diode laser absorption spectroscopy-based methane sensor, employing a dense-pattern multi-pass gas cell and a 3.3 µm, CW, DFB, room temperature interband cascade laser (ICL), is reported. The optical integration based on an advanced folded optical path design and an efficient ICL control system with appropriate electrical power management resulted in a CH 4 sensor with a small footprint (32 x 20 x 17 cm 3) and low-power consumption (6 W). Polynomial and least-squares fit algorithms are employed to remove the baseline of the spectral scan and retrieve CH 4 concentrations, respectively. An Allan-Werle deviation analysis shows that themore » measurement precision can reach 1.4 ppb for a 60 s averaging time. Continuous measurements covering a seven-day period were performed to demonstrate the stability and robustness of the reported CH 4 sensor system.« less

The fast and accurate 3D-face scanning technology based on laser triangle sensors

NASA Astrophysics Data System (ADS)

Wang, Jinjiang; Chang, Tianyu; Ge, Baozhen; Tian, Qingguo; Chen, Yang; Kong, Bin

2013-08-01

A laser triangle scanning method and the structure of 3D-face measurement system were introduced. In presented system, a liner laser source was selected as an optical indicated signal in order to scanning a line one times. The CCD image sensor was used to capture image of the laser line modulated by human face. The system parameters were obtained by system calibrated calculated. The lens parameters of image part of were calibrated with machine visual image method and the triangle structure parameters were calibrated with fine wire paralleled arranged. The CCD image part and line laser indicator were set with a linear motor carry which can achieve the line laser scanning form top of the head to neck. For the nose is ledge part and the eyes are sunk part, one CCD image sensor can not obtain the completed image of laser line. In this system, two CCD image sensors were set symmetric at two sides of the laser indicator. In fact, this structure includes two laser triangle measure units. Another novel design is there laser indicators were arranged in order to reduce the scanning time for it is difficult for human to keep static for longer time. The 3D data were calculated after scanning. And further data processing include 3D coordinate refine, mesh calculate and surface show. Experiments show that this system has simply structure, high scanning speed and accurate. The scanning range covers the whole head of adult, the typical resolution is 0.5mm.

Precision and resolution in laser direct microstructuring with bursts of picosecond pulses

NASA Astrophysics Data System (ADS)

Mur, Jaka; Petkovšek, Rok

2018-01-01

Pulsed laser sources facilitate various applications, including efficient material removal in different scientific and industrial applications. Commercially available laser systems in the field typically use a focused laser beam of 10-20 μm in diameter. In line with the ongoing trends of miniaturization, we have developed a picosecond fiber laser-based system combining fast beam deflection and tight focusing for material processing and optical applications. We have predicted and verified the system's precision, resolution, and minimum achievable feature size for material processing applications. The analysis of the laser's performance requirements for the specific applications of high-precision laser processing is an important aspect for further development of the technique. We have predicted and experimentally verified that maximal edge roughness of single-micrometer-sized features was below 200 nm, including the laser's energy and positioning stability, beam deflection, the effect of spot spacing, and efficient isolation of mechanical vibrations. We have demonstrated that a novel fiber laser operating regime in bursts of pulses increases the laser energy stability. The results of our research improve the potential of fiber laser sources for material processing applications and facilitate their use through enabling the operation at lower pulse energies in bursts as opposed to single pulse regimes.

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.

Comparative study of diode-pumped alkali vapor laser and exciplex-pumped alkali laser systems and selection principal of parameters

NASA Astrophysics Data System (ADS)

Huang, Wei; Tan, Rongqing; Li, Zhiyong; Han, Gaoce; Li, Hui

2017-03-01

A theoretical model based on common pump structure is proposed to analyze the output characteristics of a diode-pumped alkali vapor laser (DPAL) and XPAL (exciplex-pumped alkali laser). Cs-DPAL and Cs-Ar XPAL systems are used as examples. The model predicts that an optical-to-optical efficiency approaching 80% can be achieved for continuous-wave four- and five-level XPAL systems with broadband pumping, which is several times the pumped linewidth for DPAL. Operation parameters including pumped intensity, temperature, cell's length, mixed gas concentration, pumped linewidth, and output coupler are analyzed for DPAL and XPAL systems based on the kinetic model. In addition, the predictions of selection principal of temperature and cell's length are also presented. The concept of the equivalent "alkali areal density" is proposed. The result shows that the output characteristics with the same alkali areal density but different temperatures turn out to be equal for either the DPAL or the XPAL system. It is the areal density that reflects the potential of DPAL or XPAL systems directly. A more detailed analysis of similar influences of cavity parameters with the same areal density is also presented.

Shuttle Laser Altimeter

NASA Technical Reports Server (NTRS)

Bufton, Jack L.; Harding, David J.; Garvin, James B.

1999-01-01

The Shuttle Laser Altimeter (SLA) is a Hitchhiker experiment that has flown twice; first on STS-72 in January 1996 and then on STS-85 in August 1997. Both missions produced successful laser altimetry and surface lidar data products from approximately 80 hours per mission of SLA data operations. A total of four Shuttle missions are planned for the SLA series. This paper documents SLA mission results and explains SLA pathfinder accomplishments at the mid-point in this series of Hitchhiker missions. The overall objective of the SLA mission series is the transition of the Goddard Space Flight Center airborne laser altimeter and lidar technology to low Earth orbit as a pathfinder for NASA operational space-based laser remote sensing devices. Future laser altimeter sensors will utilize systems and approaches being tested with SLA, including the Multi-Beam Laser Altimeter (MBLA) and the Geoscience Laser Altimeter System (GLAS). MBLA is the land and vegetation laser sensor for the NASA Earth System Sciences Pathfinder Vegetation Canopy Lidar (VCL) Mission, and GLAS is the Earth Observing System facility instrument on the Ice, Cloud, and Land Elevation Satellite (ICESat). The Mars Orbiting Laser Altimeter, now well into a multi-year mapping mission at the red planet, is also directly benefiting from SLA data analysis methods, just as SLA benefited from MOLA spare parts and instrument technology experience [5] during SLA construction in the early 1990s.

Pulsed laser diode photoacoustic tomography (PLD-PAT) system for fast in vivo imaging of small animal brain

NASA Astrophysics Data System (ADS)

Upputuri, Paul Kumar; Kalva, Sandeep Kumar; Moothanchery, Mohesh; Pramanik, Manojit

2017-03-01

In recent years, high-repetition rate pulsed laser diode (PLD) was used as an alternative to the Nd:YAG lasers for photoacoustic tomography (PAT). The use of PLD makes the overall PAT system, a low-cost, portable, and high frame rate imaging tool for preclinical applications. In this work, we will present a portable in vivo pulsed laser diode based photoacoustic tomography (PLD-PAT) system. The PLD is integrated inside a circular scanning geometry. The PLD can provide near-infrared ( 803 nm) pulses with pulse duration 136 ns, and pulse energy 1.4 mJ / pulse at 7 kHz repetition rate. The system will be demonstrated for in vivo fast imaging of small animal brain. To enhance the contrast of brain imaging, experiments will be carried out using contrast agents which have strong absorption around laser excitation wavelength. This low-cost, portable small animal brain imaging system could be very useful for brain tumor imaging and therapy.

Interaction dynamics of fs-laser induced cavitation bubbles and their impact on the laser-tissue-interaction of modern ophthalmic laser systems

NASA Astrophysics Data System (ADS)

Tinne, N.; Ripken, T.; Lubatschowski, H.; Heisterkamp, A.

2011-07-01

A today well-known laser based treatment in ophthalmology is the LASIK procedure which nowadays includes cutting of the corneal tissue with ultra-short laser pulses. Instead of disposing a microkeratome for cutting a corneal flap, a focused ultra-short laser pulse is scanned below the surface of biological tissue causing the effect of an optical breakdown and hence obtaining a dissection. Inside the tissue, the energy of the laser pulses is absorbed by non-linear processes; as a result a cavitation bubble expands and ruptures the tissue. Hence, positioning of several optical breakdowns side by side generates an incision. Due to a reduction of the amount of laser energy, with a moderate duration of treatment at the same time, the current development of ultra-short pulse laser systems points to higher repetition rates in the range of even Megahertz instead of tens or hundreds of Kilohertz. In turn, this results in a pulse overlap and therefor a probable occurrence of interaction between different optical breakdowns and respectively cavitation bubbles of adjacent optical breakdowns. While the interaction of one single laser pulse with biological tissue is analyzed reasonably well experimentally and theoretically, the interaction of several spatial and temporal following pulses is scarcely determined yet. Thus, the aim of this study is to analyse the dynamic and interaction of two cavitation bubbles by using high speed photography. The applied laser pulse energy, the energy ratio and the spot distance between different cavitation bubbles were varied. Depending on a change of these parameters different kinds of interactions such as a flattening and deformation of bubble shape or jet formation are observed. The effects will be discussed regarding the medical ophthalmic application of fs-lasers. Based on these results a further research seems to be inevitable to comprehend and optimize the cutting effect of ultra-short pulse laser systems with high (> 500 kHz) repetition rates.

Design of laser afocal zoom expander system

NASA Astrophysics Data System (ADS)

Jiang, Lian; Zeng, Chun-Mei; Hu, Tian-Tian

2018-01-01

Laser afocal zoom expander system due to the beam diameter variable, can be used in the light sheet illumination microscope to observe the samples of different sizes. Based on the principle of afocal zoom system, the laser collimation and beam expander system with a total length of less than 110mm, 6 pieces of spherical lens and a beam expander ratio of 10 is designed by using Zemax software. The system is focused on laser with a wavelength of 532nm, divergence angle of less than 4mrad and incident diameter of 4mm. With the combination of 6 spherical lens, the beam divergence angle is 0.4mrad at the maximum magnification ratio, and the RMS values at different rates are less than λ/4. This design is simple in structure and easy to process and adjust. It has certain practical value.

Photocrosslinking and Photodamage in Protein-Nucleic Acid Systems Resulting from UV and IR Radiation.

NASA Astrophysics Data System (ADS)

Kozub, John Andrew

1995-01-01

Photocrosslinking of protein-nucleic acid complexes with low intensity UV has frequently been used to study biological systems. We have investigated the photochemistry of protein-nucleic acid systems using nanosecond UV pulses from a Nd:YAG-pumped dye laser system, low-intensity continuous UV from a typical germicidal lamp, and high-intensity mid -IR pulses from the Vanderbilt Free Electron Laser. Quantum yields for UV-induced nucleic acid damage from laser pulses and the germicidal lamp were found to be nearly equivalent. We have demonstrated the general applicability of the laser to this technique by successfully crosslinking hnRNP protein to RNA, yeast TATA-binding protein to dsDNA, and gene 32 protein to ssDNA with UV laser pulses. Our results indicate that UV-crosslinking has an intrinsic specificity for nucleic acid sites containing thymidine (or uridine), forcing a distinction between preferred binding sites and favorable crosslinking sites. We have found in each system that protein and nucleic acid photodamage competes with crosslinking, limits the yield, and may interfere with subsequent analysis. The distribution of photoproducts in the gene 32 protein-ssDNA system was investigated as a function of the total dose of UV radiation and the intensity of UV laser pulses. It was found that laser pulses providing up to 50 photons per nucleic acid base induce a linear response from the system; the absolute and relative yields of photoproducts depend only on the total dose of UV and not on the rate of delivery. At higher intensities, the yield of crosslinks per incident photon was reduced. A single pulse at the optimum intensity (about 100-200 photons per nucleic acid base) induced roughly 80% of the maximum attainable yield of crosslinks in this system. The early results of our search for photochemistry induced by Free Electron Laser pulses indicate the potential to induce a unique photoreaction in the gene 32 protein -ssDNA system. The yield is apparently enhanced by simultaneous exposure to UV pulses. Future experiments will test the potential of IR and UV irradiations to increase the specificity for photocrosslinks.

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.

Design of a dual species atom interferometer for space

NASA Astrophysics Data System (ADS)

Schuldt, Thilo; Schubert, Christian; Krutzik, Markus; Bote, Lluis Gesa; Gaaloul, Naceur; Hartwig, Jonas; Ahlers, Holger; Herr, Waldemar; Posso-Trujillo, Katerine; Rudolph, Jan; Seidel, Stephan; Wendrich, Thijs; Ertmer, Wolfgang; Herrmann, Sven; Kubelka-Lange, André; Milke, Alexander; Rievers, Benny; Rocco, Emanuele; Hinton, Andrew; Bongs, Kai; Oswald, Markus; Franz, Matthias; Hauth, Matthias; Peters, Achim; Bawamia, Ahmad; Wicht, Andreas; Battelier, Baptiste; Bertoldi, Andrea; Bouyer, Philippe; Landragin, Arnaud; Massonnet, Didier; Lévèque, Thomas; Wenzlawski, Andre; Hellmig, Ortwin; Windpassinger, Patrick; Sengstock, Klaus; von Klitzing, Wolf; Chaloner, Chris; Summers, David; Ireland, Philip; Mateos, Ignacio; Sopuerta, Carlos F.; Sorrentino, Fiodor; Tino, Guglielmo M.; Williams, Michael; Trenkel, Christian; Gerardi, Domenico; Chwalla, Michael; Burkhardt, Johannes; Johann, Ulrich; Heske, Astrid; Wille, Eric; Gehler, Martin; Cacciapuoti, Luigi; Gürlebeck, Norman; Braxmaier, Claus; Rasel, Ernst

2015-06-01

Atom interferometers have a multitude of proposed applications in space including precise measurements of the Earth's gravitational field, in navigation & ranging, and in fundamental physics such as tests of the weak equivalence principle (WEP) and gravitational wave detection. While atom interferometers are realized routinely in ground-based laboratories, current efforts aim at the development of a space compatible design optimized with respect to dimensions, weight, power consumption, mechanical robustness and radiation hardness. In this paper, we present a design of a high-sensitivity differential dual species 85Rb/87Rb atom interferometer for space, including physics package, laser system, electronics and software. The physics package comprises the atom source consisting of dispensers and a 2D magneto-optical trap (MOT), the science chamber with a 3D-MOT, a magnetic trap based on an atom chip and an optical dipole trap (ODT) used for Bose-Einstein condensate (BEC) creation and interferometry, the detection unit, the vacuum system for 10-11 mbar ultra-high vacuum generation, and the high-suppression factor magnetic shielding as well as the thermal control system. The laser system is based on a hybrid approach using fiber-based telecom components and high-power laser diode technology and includes all laser sources for 2D-MOT, 3D-MOT, ODT, interferometry and detection. Manipulation and switching of the laser beams is carried out on an optical bench using Zerodur bonding technology. The instrument consists of 9 units with an overall mass of 221 kg, an average power consumption of 608 W (814 W peak), and a volume of 470 liters which would well fit on a satellite to be launched with a Soyuz rocket, as system studies have shown.

Plume Image Profiling of UV Laser Desorbed Biomolecules

NASA Astrophysics Data System (ADS)

Merrigan, T. L.; Hunniford, C. A.; Timson, D. J.; Catney, M.; McCullough, R. W.

2008-12-01

An experimental system, based upon the techniques of UV and IR laser desorption with time of flight mass spectrometry, has been constructed to enable the production and characterization of neutral biomolecular targets. The feasibility of the laser desorption technique for the purpose of radiation interaction experiments is investigated here. Fluorescent dye tagging and laser induced fluorescence imaging has been used to help characterize the laser produced plumes of biomolecules revealing their spatial density profiles and temporal evolution. Peak target thicknesses of 2×1012 molecules cm-2 were obtained 30 μs after laser desorption.

Evaluation of Analysis Conditions for Laser-Pulsed Atom Probe Tomography: Example of Cemented Tungsten Carbide.

PubMed

Peng, Zirong; Choi, Pyuck-Pa; Gault, Baptiste; Raabe, Dierk

2017-04-01

Cemented tungsten carbide has been analyzed using laser-pulsed atom probe tomography (APT). The influence of experimental parameters, including laser pulse energy, pulse repetition rate, and specimen base temperature, on the acquired data were evaluated from different aspects, such as mass spectrum, chemical composition, noise-to-signal ratio, and multiple events. Within all the applied analysis conditions, only 1 MHz pulse repetition rate led to a strong detector saturation effect, resulting in a largely biased chemical composition. A comparative study of the laser energy settings showed that an ~12 times higher energy was required for the less focused green laser of the LEAPTM 3000X HR system to achieve a similar evaporation field as the finer spot ultraviolet laser of the LEAPTM 5000 XS system.

Precision Laser Development for Interferometric Space Missions NGO, SGO, and GRACE Follow-On

NASA Technical Reports Server (NTRS)

Numata, Kenji; Camp, Jordan

2011-01-01

Optical fiber and semiconductor laser technologies have evolved dramatically over the last decade due to the increased demands from optical communications. We are developing a laser (master oscillator) and optical amplifier based on those technologies for interferometric space missions, including the gravitational-wave missions NGO/SGO (formerly LISA) and the climate monitoring mission GRACE Follow-On, by fully utilizing the matured wave-guided optics technologies. In space, where simpler and more reliable system is preferred, the wave-guided components are advantageous over bulk, crystal-based, free-space laser, such as NPRO (Nonplanar Ring Oscillator) and bulk-crystal amplifier.

A Fiber Bragg Grating Sensor Interrogation System Based on a Linearly Wavelength-Swept Thermo-Optic Laser Chip

PubMed Central

Lee, Hyung-Seok; Lee, Hwi Don; Kim, Hyo Jin; Cho, Jae Du; Jeong, Myung Yung; Kim, Chang-Seok

2014-01-01

A linearized wavelength-swept thermo-optic laser chip was applied to demonstrate a fiber Bragg grating (FBG) sensor interrogation system. A broad tuning range of 11.8 nm was periodically obtained from the laser chip for a sweep rate of 16 Hz. To measure the linear time response of the reflection signal from the FBG sensor, a programmed driving signal was directly applied to the wavelength-swept laser chip. The linear wavelength response of the applied strain was clearly extracted with an R-squared value of 0.99994. To test the feasibility of the system for dynamic measurements, the dynamic strain was successfully interrogated with a repetition rate of 0.2 Hz by using this FBG sensor interrogation system. PMID:25177803

Airborne space laser communication system and experiments

NASA Astrophysics Data System (ADS)

Li, Xiao-Ming; Zhang, Li-zhong; Meng, Li-Xin

2015-11-01

Airborne space laser communication is characterized by its high speed, anti-electromagnetic interference, security, easy to assign. It has broad application in the areas of integrated space-ground communication networking, military communication, anti-electromagnetic communication. This paper introduce the component and APT system of the airborne laser communication system design by Changchun university of science and technology base on characteristic of airborne laser communication and Y12 plan, especially introduce the high communication speed and long distance communication experiment of the system that among two Y12 plans. In the experiment got the aim that the max communication distance 144Km, error 10-6 2.5Gbps - 10-7 1.5Gbps capture probability 97%, average capture time 20s. The experiment proving the adaptability of the APT and the high speed long distance communication.

Advanced Accelerators for Medical Applications

NASA Astrophysics Data System (ADS)

Uesaka, Mitsuru; Koyama, Kazuyoshi

We review advanced accelerators for medical applications with respect to the following key technologies: (i) higher RF electron linear accelerator (hereafter “linac”); (ii) optimization of alignment for the proton linac, cyclotron and synchrotron; (iii) superconducting magnet; (iv) laser technology. Advanced accelerators for medical applications are categorized into two groups. The first group consists of compact medical linacs with high RF, cyclotrons and synchrotrons downsized by optimization of alignment and superconducting magnets. The second group comprises laser-based acceleration systems aimed of medical applications in the future. Laser plasma electron/ion accelerating systems for cancer therapy and laser dielectric accelerating systems for radiation biology are mentioned. Since the second group has important potential for a compact system, the current status of the established energy and intensity and of the required stability are given.

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

High energy diode-pumped solid-state laser development at the Central Laser Facility

NASA Astrophysics Data System (ADS)

Mason, Paul D.; Banerjee, Saumyabrata; Ertel, Klaus; Phillips, P. Jonathan; Butcher, Thomas; Smith, Jodie; De Vido, Mariastefania; Chekhlov, Oleg; Hernandez-Gomez, Cristina; Edwards, Chris; Collier, John

2016-04-01

In this paper we review the development of high energy, nanosecond pulsed diode-pumped solid state lasers within the Central Laser Facility (CLF) based on cryogenic gas cooled multi-slab ceramic Yb:YAG amplifier technology. To date two 10J-scale systems, the DiPOLE prototype amplifier and an improved DIPOLE10 system, have been developed, and most recently a larger scale system, DiPOLE100, designed to produce 100 J pulses at up to 10 Hz. These systems have demonstrated amplification of 10 ns duration pulses at 1030 nm to energies in excess of 10 J at 10 Hz pulse repetition rate, and over 100 J at 1 Hz, with optical-to-optical conversion efficiencies of up to 27%. We present an overview of the cryo-amplifier concept and compare the design features of these three systems, including details of the amplifier designs, gain media, diode pump lasers and the cryogenic gas cooling systems. The most recent performance results from the three systems are presented along with future plans for high energy DPSSL development within the CLF.

Initial results from the Lick Observatory Laser Guide Star Adaptive Optics System

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

Olivier, S.S.; An, J.; Avicola, K.

1995-11-08

A prototype adaptive optics system has been installed and tested on the 3 m Shane telescope at Lick Observatory. The adaptive optics system performance, using bright natural guide stars, is consistent with expectations based on theory. A sodium-layer laser guide star system has also been installed and tested on the Shane telescope. Operating at 15 W, the laser system produces a 9th magnitude guide star with seeing-limited size at 589 nm. Using the laser guide star, the adaptive optics system has reduced the wavefront phase variance on scales above 50 cm by a factor of 4. These results represent themore » first continuous wavefront phase correction using a sodium-layer laser guide star. Assuming tip-tilt is removed using a natural guide star, the measured control loop performance should produce images with a Strehl ratio of 0.4 at 2.2 {mu}m in 1 arc second seeing. Additional calibration procedures must be implemented in order to achieve these results with the prototype Lick adaptive optics system.« less

Mid-IR laser system for advanced neurosurgery

NASA Astrophysics Data System (ADS)

Klosner, M.; Wu, C.; Heller, D. F.

2014-03-01

We present work on a laser system operating in the near- and mid-IR spectral regions, having output characteristics designed to be optimal for cutting various tissue types. We provide a brief overview of laser-tissue interactions and the importance of controlling certain properties of the light beam. We describe the principle of operation of the laser system, which is generally based on a wavelength-tunable alexandrite laser oscillator/amplifier, and multiple Raman conversion stages. This configuration provides robust access to the mid-IR spectral region at wavelengths, pulse energies, pulse durations, and repetition rates that are attractive for neurosurgical applications. We summarize results for ultra-precise selective cutting of nerve sheaths and retinas with little collateral damage; this has applications in procedures such as optic-nerve-sheath fenestration and possible spinal repair. We also report results for cutting cornea, and dermal tissues.

Strategic Defense Initiative Program: Extent of Foreign Participation

DTIC Science & Technology

1990-02-07

the Air Force to a West German company, . Chemical Lasers project, for fabrication of a lightweight hig mirror . The firished product will be a 70...centimeter mirror lightweight, uncool"P glass ceramic material with no tus.rm. Two contracts, totaling $1.7 million, were au-arded under th Definition...Ground-Based Free The ground-based laser system concept is to fire a free electrru Electron Laser Project beam generated on the ground to a mirror relay

Spacecraft system study: A study to define the impact of laser communication systems on their host spacecraft

NASA Technical Reports Server (NTRS)

1984-01-01

The mutual influence of a laser communication system and its host spacecraft and the degree to which the mutual influence limited acquisition, tracking and pointing processes were investigated. A laser klink between a low earth orbiting (LEO) satellite and a geosynchronous earth orbiting (GEO) satellite was used as a baseline. The laser link between satellites was a generic channel transferring 500 Mbps data from the LEO to GEO using the GaAlAs laser as the laser light source. Major aspects of pointing and tracking with a satelliteborne optical system were evaluated including: (1) orbital aspects such as spacecraft relative motions, point ahead, and Sun snd Moon optical noise; (2) burst errors introduced by the electronic and optical noise levels; (3) servo system design and configurations, and the noise sources such as, sensor noise, base motion disturbances, gimbal friction torque noise; (4) an evaluation of the tracking and beacon link and the type of sensors used; (5) the function of the acquisition procedure and an evaluation of the sensors employed; and (6) an estimate of the size, weight and power needed for the satellite system.