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Sample records for high-speed laser micromachining

  1. Ultra high-speed micromachining of transparent materials using high PRF ultrafast lasers and new resonant scanning systems

    NASA Astrophysics Data System (ADS)

    Harth, F.; Piontek, M. C.; Herrmann, T.; L'huillier, J. A.

    2016-03-01

    Irradiation of focused laser pulses to transparent materials leads to structural changes and can be used for the fabrication of e.g. LED light guiding components. In these applications both small spot sizes and a high lateral resolution in the μm range are absolutely essential. In order to achieve the industrially required throughput of nearly one million laser markings per second, ultrafast lasers with 100 W of average power and pulse repetition frequencies of several MHz are required. Laser machining of polymers additionally necessitates a wide spatial separation of the markings to avoid heat accumulation effects. Therefore, neither commercially available galvanometer based nor Polygon based scanners with their limited scan speed can be used for beam deflection. In our work, we developed an experimental setup based

  2. Micromachining with copper lasers

    NASA Astrophysics Data System (ADS)

    Knowles, Martyn R. H.; Bell, Andy; Foster-Turner, Gideon; Rutterford, Graham; Chudzicki, J.; Kearsley, Andrew J.

    1997-04-01

    In recent years the copper laser has undergone extensive development and has emerged as a leading and unique laser for micromachining. The copper laser is a high average power (10 - 250 W), high pulse repetition rate (2 - 32 kHz), visible laser (511 nm and 578 nm) that produces high peak power (typically 200 kW), short pulses (30 ns) and very good beam quality (diffraction limited). This unique set of laser parameters results in exceptional micro-machining in a wide variety of materials. Typical examples of the capabilities of the copper laser include the drilling of small holes (10 - 200 micrometer diameter) in materials as diverse as steel, ceramic, diamond and polyimide with micron precision and low taper (less than 1 degree) cutting and profiling of diamond. Application of the copper laser covers the electronic, aerospace, automotive, nuclear, medical and precision engineering industries.

  3. High-speed AFM probe with micromachined membrane tip

    NASA Astrophysics Data System (ADS)

    Kim, Byungki; Kwak, Byung Hyung; Jamil, Faize

    2008-08-01

    This paper presents a micromachined silicon membrane type AFM tip designed to move nearly 1µm by electrostatic force. Since the tip can be vibrated in small amplitude with AC voltage input and can be displaced up to 1μm by DC voltage input, an additional piezo actuator is not required for scanning of submicron features. The micromachined membrane tips are designed to have 100 kHz ~ 1 MHz resonant frequency. Displacement of the membrane tip is measured by an optical interferometer using a micromachined diffraction grating on a quartz wafer which is positioned behind the membrane tip.

  4. Trends in laser micromachining

    NASA Astrophysics Data System (ADS)

    Gaebler, Frank; van Nunen, Joris; Held, Andrew

    2016-03-01

    Laser Micromachining is well established in industry. Depending on the application lasers with pulse length from μseconds to femtoseconds and wavelengths from 1064nm and its harmonics up to 5μm or 10.6μm are used. Ultrafast laser machining using pulses with pico or femtosecond duration pulses is gaining traction, as it offers very precise processing of materials with low thermal impact. Large-scale industrial ultrafast laser applications show that the market can be divided into various sub segments. One set of applications demand low power around 10W, compact footprint and are extremely sensitive to the laser price whilst still demanding 10ps or shorter laser pulses. A second set of applications are very power hungry and only become economically feasible for large scale deployments at power levels in the 100+W class. There is also a growing demand for applications requiring fs-laser pulses. In our presentation we would like to describe these sub segments by using selected applications from the automotive and electronics industry e.g. drilling of gas/diesel injection nozzles, dicing of LED substrates. We close the presentation with an outlook to micromachining applications e.g. glass cutting and foil processing with unique new CO lasers emitting 5μm laser wavelength.

  5. Micromachining using femtosecond lasers

    NASA Astrophysics Data System (ADS)

    Toenshoff, Hans K.; Ostendorf, Andreas; Nolte, Stefan; Korte, Frank; Bauer, Thorsten

    2000-11-01

    Femtosecond laser systems have been proved to be effective tools for high precision micro-machining. Almost all solid materials can be processed with high precision. The dependence on material properties like thermal conductivity, transparency, heat- or shock sensitivity is strongly reduced and no significant influence on the remaining bulk material is observed after ablation using femtosecond laser pulses. In contrast to conventional laser processing, where the achievable precision is reduced due to a formed liquid phase causing burr formation, the achievable precision using femtosecond pulses is only limited by the diffraction of the used optics. Potential applications of this technique, aincluding the structuring of biodegradable polymers for cardiovascular implants, so-called stents, as well as high precision machining of transparent materials are presented.

  6. Laser Trigger For High Speed Camera

    NASA Astrophysics Data System (ADS)

    Chang, Rong-Seng; Lin, Chin-Wu; Cheng, Tung

    1987-09-01

    High speed camera coorperated with laser trigger to catch high speed unpredictable events has many applications: such as scoring system for the end game of missile interception, war head explosive study etc. When the event happening in a very short duration, the repetition rate of the laser ranging must be as high as 5K herze and the pulse duration should be less than 10 nsec. In some environment, like inside the aircraft, the abailable space for high speed camera to set up is limited, large film capacity camera could not be used. In order to use the small capacity film, the exact trigger time for the camera are especially important. The target velocity, camera acceleration characteristics, speed regulation, camera size, weight and the ruggedness are all be considered before the laser trigger be designed. Electric temporal gate is used to measure the time of flight ranging datum. The triangular distance measurement principle are also used to get the ranging when the base line i.e. the distance between the laser transmitter and receiver are large enough.

  7. Pulsed laser triggered high speed microfluidic switch

    NASA Astrophysics Data System (ADS)

    Wu, Ting-Hsiang; Gao, Lanyu; Chen, Yue; Wei, Kenneth; Chiou, Pei-Yu

    2008-10-01

    We report a high-speed microfluidic switch capable of achieving a switching time of 10 μs. The switching mechanism is realized by exciting dynamic vapor bubbles with focused laser pulses in a microfluidic polydimethylsiloxane (PDMS) channel. The bubble expansion deforms the elastic PDMS channel wall and squeezes the adjacent sample channel to control its fluid and particle flows as captured by the time-resolved imaging system. A switching of polystyrene microspheres in a Y-shaped channel has also been demonstrated. This ultrafast laser triggered switching mechanism has the potential to advance the sorting speed of state-of-the-art microscale fluorescence activated cell sorting devices.

  8. Fiber laser for high speed laser transfer printing

    NASA Astrophysics Data System (ADS)

    Petkovšek, Rok; Novak, Vid; Agrež, Vid

    2017-01-01

    High speed industrial laser transfer printing requires high power lasers that can deliver pulses on demand and having arbitrary pulse duration in range of few nanoseconds to milliseconds or more. A special kind of MOPA fiber laser is presented using wavelength multiplexing to achieve pulses on demand with minimal transients. The system is further tested in printing application.

  9. High speed sampling circuit design for pulse laser ranging

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    In recent years, with the rapid development of digital chip, high speed sampling rate analog to digital conversion chip can be used to sample narrow laser pulse echo. Moreover, high speed processor is widely applied to achieve digital laser echo signal processing algorithm. The development of digital chip greatly improved the laser ranging detection accuracy. High speed sampling and processing circuit used in the laser ranging detection system has gradually been a research hotspot. In this paper, a pulse laser echo data logging and digital signal processing circuit system is studied based on the high speed sampling. This circuit consists of two parts: the pulse laser echo data processing circuit and the data transmission circuit. The pulse laser echo data processing circuit includes a laser diode, a laser detector and a high sample rate data logging circuit. The data transmission circuit receives the processed data from the pulse laser echo data processing circuit. The sample data is transmitted to the computer through USB2.0 interface. Finally, a PC interface is designed using C# language, in which the sampling laser pulse echo signal is demonstrated and the processed laser pulse is plotted. Finally, the laser ranging experiment is carried out to test the pulse laser echo data logging and digital signal processing circuit system. The experiment result demonstrates that the laser ranging hardware system achieved high speed data logging, high speed processing and high speed sampling data transmission.

  10. A review of ultrafast laser materials micromachining

    NASA Astrophysics Data System (ADS)

    Cheng, Jian; Liu, Chang-sheng; Shang, Shuo; Liu, Dun; Perrie, Walter; Dearden, Geoff; Watkins, Ken

    2013-03-01

    A brief review is given regarding ultrafast laser micromachining of materials. Some general experimental observations are first provided to show the characteristics of ultrafast laser micromachining. Apart from empirical research, mathematical models also appear to allow for a further and systematic understanding of these phenomena. A few fundamental ultrafast laser micromachining mechanisms are addressed in an attempt to highlight the physics behind the experimental observations and the mathematical models. It is supposed that a vivid view of ultrafast laser micromachining has been presented by linking experimental observations, mathematical models and the behind physics.

  11. Apparatus for precision micromachining with lasers

    DOEpatents

    Chang, Jim J.; Dragon, Ernest P.; Warner, Bruce E.

    1998-01-01

    A new material processing apparatus using a short-pulsed, high-repetition-rate visible laser for precision micromachining utilizes a near diffraction limited laser, a high-speed precision two-axis tilt-mirror for steering the laser beam, an optical system for either focusing or imaging the laser beam on the part, and a part holder that may consist of a cover plate and a back plate. The system is generally useful for precision drilling, cutting, milling and polishing of metals and ceramics, and has broad application in manufacturing precision components. Precision machining has been demonstrated through percussion drilling and trepanning using this system. With a 30 W copper vapor laser running at multi-kHz pulse repetition frequency, straight parallel holes with size varying from 500 microns to less than 25 microns and with aspect ratios up to 1:40 have been consistently drilled with good surface finish on a variety of metals. Micromilling and microdrilling on ceramics using a 250 W copper vapor laser have also been demonstrated with good results. Materialogroaphic sections of machined parts show little (submicron scale) recast layer and heat affected zone.

  12. Apparatus for precision micromachining with lasers

    DOEpatents

    Chang, J.J.; Dragon, E.P.; Warner, B.E.

    1998-04-28

    A new material processing apparatus using a short-pulsed, high-repetition-rate visible laser for precision micromachining utilizes a near diffraction limited laser, a high-speed precision two-axis tilt-mirror for steering the laser beam, an optical system for either focusing or imaging the laser beam on the part, and a part holder that may consist of a cover plate and a back plate. The system is generally useful for precision drilling, cutting, milling and polishing of metals and ceramics, and has broad application in manufacturing precision components. Precision machining has been demonstrated through percussion drilling and trepanning using this system. With a 30 W copper vapor laser running at multi-kHz pulse repetition frequency, straight parallel holes with size varying from 500 microns to less than 25 microns and with aspect ratios up to 1:40 have been consistently drilled with good surface finish on a variety of metals. Micromilling and microdrilling on ceramics using a 250 W copper vapor laser have also been demonstrated with good results. Materialographic sections of machined parts show little (submicron scale) recast layer and heat affected zone. 1 fig.

  13. Micromachining of Silicon Carbide using femtosecond lasers

    NASA Astrophysics Data System (ADS)

    Farsari, M.; Filippidis, G.; Zoppel, S.; Reider, G. A.; Fotakis, C.

    2007-04-01

    We have demonstrated micromachining of bulk 3C silicon carbide (3C- SiC) wafers by employing 1028nm wavelength femtosecond laser pulses of energy less than 10 nJ directly from a femtosecond laser oscillator, thus eliminating the need for an amplified system and increasing the micromachining speed by more than four orders of magnitude.

  14. High-speed vertical cavity surface emitting lasers

    SciTech Connect

    Lear, K.L.; Ochiai, M.; Hietala, V.M.

    1997-03-01

    High speed modulation and pulsing are reported for oxide-confined vertical cavity surface emitting laser diodes (VCSELs) with inverted doping and proton implantation to reduce the extrinsic limitations.

  15. Method and apparatus for precision laser micromachining

    DOEpatents

    Chang, Jim; Warner, Bruce E.; Dragon, Ernest P.

    2000-05-02

    A method and apparatus for micromachining and microdrilling which results in a machined part of superior surface quality is provided. The system uses a near diffraction limited, high repetition rate, short pulse length, visible wavelength laser. The laser is combined with a high speed precision tilting mirror and suitable beam shaping optics, thus allowing a large amount of energy to be accurately positioned and scanned on the workpiece. As a result of this system, complicated, high resolution machining patterns can be achieved. A cover plate may be temporarily attached to the workpiece. Then as the workpiece material is vaporized during the machining process, the vapors condense on the cover plate rather than the surface of the workpiece. In order to eliminate cutting rate variations as the cutting direction is varied, a randomly polarized laser beam is utilized. A rotating half-wave plate is used to achieve the random polarization. In order to correctly locate the focus at the desired location within the workpiece, the position of the focus is first determined by monitoring the speckle size while varying the distance between the workpiece and the focussing optics. When the speckle size reaches a maximum, the focus is located at the first surface of the workpiece. After the location of the focus has been determined, it is repositioned to the desired location within the workpiece, thus optimizing the quality of the machined area.

  16. Review of laser micromachining in contract manufacturing

    NASA Astrophysics Data System (ADS)

    Ogura, Glenn; Gu, Bo

    1998-06-01

    This paper explores the wide range of laser micromachining applications used in contract manufacturing. Contract manufacturing is used in several key industries such as microelectronics packaging, semiconductor, data storage, medical devices, communications, peripherals, automobiles and aerospace. Material types includes plastics, metals, ceramics, inorganics and composites. However laser micromachining is just one available technology for micromachining and other methods will be reviewed. Contract manufacturing offers two important glimpses of the future. Firstly prototype work for new applications often beings in contract manufacturing. Secondly, contract manufacturing can be an economic springboard to allow laser systems to be installed in a production environment.

  17. Micromachined sensors and actuators for fluid mechanics research and high-speed flow control applications

    NASA Astrophysics Data System (ADS)

    Huang, Chunchieh

    Understanding the physics of turbulence and fluid dynamics is crucial to prevent unsteady and potentially dangerous flow fluctuations in aviation systems. One such condition occurs in high-speed jets when air exiting a jet nozzle at high velocity produce a high-frequency acoustic wave called "jet screech". The resulting large acoustic pressure fluctuations produce high noise levels and may result in structure failure. It is postulated that by introducing perturbations into the shear layer using microactuators, it may be possible to interfere with the screech feedback loop to control and cancel screech. This research concentrates on developing new tools with Micro Electro Mechanical Systems (MEMS) technologies to control screech using microactuators placed around jet nozzle lip. The actuators can be driven by an appropriate control signal produced by measuring the flow velocity and acoustic wave pressure using micromachined hot-wire anemometers and sound detectors. The high frequency, high amplitude lateral comb drive electrostatic microactuators generate oscillations at 5kHz with amplitudes 80mum, and survive up to 320m/s when inserted 25mum into the flow. Each actuator is 1.3mm × 1.3mm and 14mum thick. Flow activity around the microactuators is monitored using on-chip silicon sound detectors and hot-wire anemometers. The detector uses ultra-thin psp{++} piezoresistors supported on a dielectric diaphragm and provides a static sensitivity of 1.1muV/V/Pa, an acoustic sensitivity of 0.18muV/V/Pa, and tolerates overload pressures >50kPa. Each detector measures 310mum × 310mum to 910mum × 910mum and has a bandwidth of 10kHz. The hot-wire anemometers is fabricated from psp{++} silicon, is 200μm×12μm×4μm, and has a measured sensitivity of 963mV/sqrt{m/s}. All these devices have survived exposure to a high-speed air jet with a maximum velocity of 320m/s. This represents the first demonstration of MEMS-based devices in such harsh conditions. A complete system

  18. Nanopatterned Quantum Dot Lasers for High Speed, High Efficiency, Operation

    DTIC Science & Technology

    2015-04-27

    SECURITY CLASSIFICATION OF: Quantum dot (QD) active regions hold potential for realizing extremely high performance semiconductor diode lasers...2009 31-Dec-2014 Approved for Public Release; Distribution Unlimited Final Report: Nanopatterned Quantum Dot Lasers for High Speed, High Efficiency...Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 quantum dots , nanopatterning, MOCVD, laser REPORT DOCUMENTATION PAGE 11

  19. 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.

  20. Laser Micromachining Fabrication of THz Components

    NASA Technical Reports Server (NTRS)

    DrouetdAubigny, C.; Walker, C.; Jones, B.; Groppi, C.; Papapolymerou, J.; Tavenier, C.

    2001-01-01

    Laser micromachining techniques can be used to fabricate high-quality waveguide structures and quasi-optical components to micrometer accuracies. Successful GHz designs can be directly scaled to THz frequencies. We expect this promising technology to allow the construction of the first fully integrated THz heterodyne imaging arrays. At the University of Arizona, construction of the first laser micromachining system designed for THz waveguide components fabrication has been completed. Once tested and characterized our system will be used to construct prototype THz lx4 focal plane mixer arrays, magic tees, AR coated silicon lenses, local oscillator source phase gratings, filters and more. Our system can micro-machine structures down to a few microns accuracy and up to 6 inches across in a short time. This paper discusses the design and performance of our micromachining system, and illustrates the type, range and performance of components this exciting new technology will make accessible to the THz community.

  1. High-speed GaInNAs laser diodes

    NASA Astrophysics Data System (ADS)

    Kondow, Masahiko; Nakahara, Kouji; Fujisaki, S.; Tanaka, Shigehisa; Kudo, M.; Taniguchi, Tadashi; Terano, A.; Uchiyama, H.

    2004-05-01

    The explosive growth of Internet/intranet traffic has created a strong demand for cost-effective high-speed light-sources to be used in local access networks and data links. The frequency of relaxation oscillation (fr) is a major factor that restricts the high-speed operation of laser diodes. To achieve a high fr, the material of an active layer should have a large differential gain. By using GaInNAs, very deep quantum wells, especially in the conduction band can be formed. Deep quantum wells bring a large differential gain. In this paper, we show how GaInNAs lasers can be applied in this application

  2. Calibration of high-speed imaging by laser triangulation.

    PubMed

    Larsson, Hans; Hertegård, Stellan

    2004-01-01

    A method was developed for absolute calibration of endoscopic vocal fold images using laser triangulation. The laser is attached to a rigid endoscope with 8-degrees angle in relation to the optical axis of the endoscope. A special software is used for calibration and measurements from high-speed images. The equipment can provide measurements both in horizontal and vertical planes, and can be used for calibrated measurements of vocal fold length, amplitude of vocal fold vibrations and vertical movements.

  3. Picosecond Semiconductor Lasers For Characterizing High-Speed Image Shutters

    NASA Astrophysics Data System (ADS)

    Pagano, T. S.; Janson, F. J.; Yates, G. J.; Jaramillo, S. A.

    1986-01-01

    A portable system that utilizes solid state electronic timing circuits and a pulsed semiconductor laser for characterizing the optical gate sequence of high-speed image shutters, including microchannel-plate intensifier tubes (MCPTs), and silicon-intensified target vidicons (SITVs), is described and compared to earlier methods of characterization. Gate sequences obtained using the system and streak camera data of the semiconductor laser pulse are presented, with a brief discussion of the electronic delay timing and avalanche circuits used in the system.

  4. Laser micromachining of goldblack coatings

    NASA Astrophysics Data System (ADS)

    Nelms, N.; Dowson, J.; Rizvi, N.; Rohr, T.

    2006-09-01

    Goldblack deposits have been used as high-absorption coatings for thermal infrared detectors for a number of years, principally on large single, or few pixel detectors. We present a new technique that allows the benefits of goldblack to be applied to the current generation of small pixel silicon micromachined thermal infrared detectors.

  5. Laser Micromachining of THz Components

    DTIC Science & Technology

    2000-09-29

    such an instrument [3] for use on the Large Binocular Telescope now being constructed on Mount Graham, Arizona. Before operation the cell is evacuated...micromachined, 2 THz array receiver being developed for SOFIA, the Stratospheric Observatory for Far Infrared •: Astronomy [3]. Test feedhorns for the array

  6. Diode Laser Diagnostics of High Speed Flows (Postprint)

    DTIC Science & Technology

    2006-10-01

    high speed flows are required. Generally, wall measurements (e.g. pressure, temperature , and heat flux) dominate the instrumentation suite routinely...from 500 to 2000 psf. Unvitiated (cold) flows have also been studied. III. Experiment TDLAS employs single mode diode lasers that are temperature ...too high because it does not account for the entropy rise due to wall friction. Therefore, the pitot pressure and thermocouple temperature probe

  7. Pulse laser high speed schlieren photographic system and its application

    NASA Astrophysics Data System (ADS)

    Lin, Yuju; Li, Shicheng; Wang, Qingyou; Ni, Wenjun; Xiang, Yong

    1989-06-01

    Two models of a pulsed Q-switched ruby laser high speed schlieren photographic system are introduced. The models are described and results are presented from tests using each model. One model is used to record the armor-piercing process of the terminal trajectory and the chamber shooting process of the midway trajectory. The other model is used to study the detonating mechanism of high energy dynamite. Also, possibilities for future development of the system are considered.

  8. Novel Applications of High Speed Optical-Injection Locked Lasers

    DTIC Science & Technology

    2010-07-31

    frequency response of high speed phototransistors . We have also shown the OIL lasers can significantly extend the reach of optical communications, to I20km...speed InP Heterojunction PhotoTransistors (HPTs). 1 HPT test wafers have been designed and taped out, consisting of single ended HPTs... phototransistors . Light transmitted by the lens fiber and waveguide into the base of the transistor modulates the base current in the device. The

  9. A decoder architecture for high-speed frre space laser communications

    NASA Technical Reports Server (NTRS)

    Cheng, Michael; Nakashima, Michael; Hamkins, Jon; Moision, Bruce; Barsoum, Maged

    2005-01-01

    We present a decoding architecture for high-speed free-space laser communications. This system will be used by NASA's Mars Laser Communication Demonstration project, the first use of high-speed laser communication from deep space.

  10. A decoder architecture for high-speed frre space laser communications

    NASA Technical Reports Server (NTRS)

    Cheng, Michael; Nakashima, Michael; Hamkins, Jon; Moision, Bruce; Barsoum, Maged

    2005-01-01

    We present a decoding architecture for high-speed free-space laser communications. This system will be used by NASA's Mars Laser Communication Demonstration project, the first use of high-speed laser communication from deep space.

  11. Laser micromachining and modification of bioabsorbable polymers

    NASA Astrophysics Data System (ADS)

    Stepak, Bogusz D.; Antończak, Arkadiusz J.; Kozioł, Paweł E.; Szustakiewicz, Konrad; Abramski, Krzysztof M.

    2014-03-01

    In this research the influence of laser micromachining on physicochemical properties of bioabsorbable polymer was investigated. Poly(l-lactide) (PLLA), commonly used for manufacturing non-permanent biomedical devices, was irradiated with varying fluences by CO2 laser and by KrF excimer laser. To evaluate modification of the material, several analytical techniques were used: ATR (attenuated total reflection), XPS (X-ray photoelectron spectroscopy) and DSC (differential scanning calorimetry). We found that the laser-affected material has lower glass transition (Tg) and melting (Tm) temperatures. CO2 and KrF excimer lasers can be successfully used for cutting and drilling of polylactide.

  12. High-Speed Operation of Interband Cascade Lasers

    NASA Technical Reports Server (NTRS)

    Soibel, Alexander; Hill, Cory J.; Keo, Sam A.; Wright, Malcom W.; Farr, William H.; Yang, Rui Q.; Liu, H. C.

    2010-01-01

    Optical sources operating in the atmospheric window of 3-5 microns are of particular interest for the development of free-space optical communication link. It is more advantageous to operate the free-space optical communication link in 3-5-microns atmospheric transmission window than at the telecom wavelength of 1.5 m due to lower optical scattering, scintillation, and background radiation. However, the realization of optical communications at the longer wavelength has encountered significant difficulties due to lack of adequate optical sources and detectors operating in the desirable wavelength regions. Interband Cascade (IC) lasers are novel semiconductor lasers that have a great potential for the realization of high-power, room-temperature optical sources in the 3-5-microns wavelength region, yet no experimental work, until this one, was done on high-speed direct modulation of IC lasers. Here, highspeed interband cascade laser, operating at wavelength 3.0 m, has been developed and the first direct measurement of the laser modulation bandwidth has been performed using a unique, highspeed quantum well infrared photodetector (QWIP). The developed laser has modulation bandwidth exceeding 3 GHz. This constitutes a significant increase of the IC laser modulation bandwidth over currently existing devices. This result has demonstrated suitability of IC lasers as a mid-IR light source for multi-GHz free-space optical communications links

  13. Application Of CO2 Lasers To High Speed Blanking

    NASA Astrophysics Data System (ADS)

    Grenier, L. E.

    1986-11-01

    While laser cutting of sheetmetal has attained wide acceptance in the automotive industry for the purposes of prototyping and very limited preproduction work, the production rates possible with currently available systems have precluded the use of this technique in a production environment. The device design to be described embodies a high speed X-Y positioner carrying a cutting head with limited Z-axis capability. This approach confers two main benefits, first, production rate is limited only by laser power, since the positioner technology selected will permit movement at rates up to 1.5 m/s (60 in/s), second, the use of a high speed non-contact surface follower to control the Z-axis movement reduces the need to clamp the workpiece rigidly to a precision reference surface. The realized reduction of the clamping requirement permits some latitude in the feed methods that can be employed, allowing the use of coil or sheet feeding as appropriate. The author will provide estimated production rates for the proposed design and demonstrate that a suitable choice of laser source and material feed will permit the production of parts at a rate and cost comparable to conventional blanking with the advantage of much greater flexibility and reduced retooling time.

  14. High-Speed Optical Diagnostics of Laser-Interactions

    NASA Astrophysics Data System (ADS)

    Bin Suaidi, Mohamad Kadim

    Available from UMI in association with The British Library. The interaction of an 8 ns, 10 mJ and 1.06 μm infrared pulse of radiation from a Q-switched Nd-YAG laser with water near a solid boundary is studied using high speed photographic techniques. The laser-liquid interaction has been used to generate high frequency sound waves by the mechanism of dielectric breakdown of the liquid around the beam waist of the focused laser beam. This leads to the production of a short duration plasma which rapidly heats and vaporises the surrounding liquid giving rise to a vapour cavity and the formation of a cavitation bubble resulting in the emission of a spherical acoustic wave. The acoustic transient associated with the breakdown, in turn interacted with a liquid-polymer interface leading to the generation of acoustic waves at this boundary and the propagation of stress-waves in the solid. Diagnostics of the laser-interaction events are recorded using a Mach-Zehnder interferometer illuminated by a sub-nanosecond nitrogen laser-pumped dye laser and computer-controlled video-imaging and capture systems. Measurements of the transient pressure distributions from the digitally recorded interferograms are carried out using a process known as Abel inversion. Dynamic photoelastic studies of the stress-waves propagation in the solid are performed using a circular polariscope arrangement thus producing the photoelastic fringe patterns. Identification of the wave structures are greatly enhanced by also recording the events in schlieren and focused shadowgraphy as well as by the combination of the above techniques. The initial part of the project also involved the design and development of a nitrogen laser and tunable dye laser system. The short-duration and high peak power output pulse of the nitrogen laser is then used to pump the dye laser giving sufficiently high power output with good spectral linewidth to provide an ideal light source for high-speed photography of the laser

  15. Pulse Laser High Speed Schlieren Photographic System And Its Application

    NASA Astrophysics Data System (ADS)

    Yuju, Lin; Shicheng, Li; Qingyou, Wang; Wenjun, Ni; Yong, Xiang; Jingliang, Shi

    1989-06-01

    The sequential pulsed, Q-switched ruby laser is used for the light source. Liodel 640 schilieren apparatus is used for the display optical system of image and flow field. The access type rotating mirror scanning high speed camera is used for recording unit. They are assembled into a complete set of Pulsed Laser High Speed Schlieren Photographic System. So far, we have designed and trial-manufactured two types. The Model I system is used for recording the armor-piercing process of the terminal trajectory and the chamber-shooting process of the midway trajectory. The better results have been obtained. The Eodel II system is used for studying the detonating mechanism of high energy dynamite. The framing pictures of the bullet flying attitude before bullet collides the target and the compressive deformation after it collides the target as well as the detonating process have been taken. These photos have provided the basis for research work. The future development of the system has also been discussed in this paper.

  16. High Speed Crystal Growth by Q-switched Laser Melting

    NASA Technical Reports Server (NTRS)

    Cullis, A. G.

    1984-01-01

    The modification of the structural and electrical properties of semiconductors short radiation pulses obtained from Q-switched lasers is described. These modifications are accomplished by high heating and cooling rates. This processing revealed novel crystal growth and high speed resolidification phenomena. The behavior of semiconductor Si is analyzed. The annealing process typically employs short pulses of radiation in or near the visible region of the spectrum. The Q-switched ruby and Nd-YAG lasers are commonly used and these are sometimes mode locked to reduce the pulse length still further. Material to be annealed can be processed with a single large area radiation spot. Alternatively, a small radiation spot size can be used and a large sample area is covered by overlapping irradiated regions.

  17. High speed laser communication network for satellite systems

    NASA Astrophysics Data System (ADS)

    Panahi, Allen; Kazemi, Alex A.

    2011-06-01

    Using optical links in space and building high speed laser communications network has proven to be an extremely complicated task and many such schemes were tried without success in the past. However, in the last few years, there has been impressive progress made to bring the concept to fruition in civilian and government-non classified projects. In this paper we will focus on the requirements of the space-based lasers and optics used for beam forming, as well as receiver antenna gain and detectors used in free space communications. High data rate, small antenna size, narrow beam divergence, and a narrow field of view are characteristics of laser communications that offer a number of potential advantages for system design. Space-based optical communications using satellites in low earth orbit (LEO) and Geo-synchronous orbits (GEO) hold great promise for the proposed Internet in the Sky network of the future. Also discussed are the critical parameters in the transmitter, channel, receiver, and link budget that are employed in successful inter-satellite communications system. We cover that Laser Communications offer a viable alternative to established RF communications for inter-satellite links and other applications where high performance links are a necessity.

  18. Submonolayer Quantum Dots for High Speed Surface Emitting Lasers

    PubMed Central

    2007-01-01

    We report on progress in growth and applications of submonolayer (SML) quantum dots (QDs) in high-speed vertical-cavity surface-emitting lasers (VCSELs). SML deposition enables controlled formation of high density QD arrays with good size and shape uniformity. Further increase in excitonic absorption and gain is possible with vertical stacking of SML QDs using ultrathin spacer layers. Vertically correlated, tilted or anticorrelated arrangements of the SML islands are realized and allow QD strain and wavefunction engineering. Respectively, both TE and TM polarizations of the luminescence can be achieved in the edge-emission using the same constituting materials. SML QDs provide ultrahigh modal gain, reduced temperature depletion and gain saturation effects when used in active media in laser diodes. Temperature robustness up to 100 °C for 0.98 μm range vertical-cavity surface-emitting lasers (VCSELs) is realized in the continuous wave regime. An open eye 20 Gb/s operation with bit error rates better than 10−12has been achieved in a temperature range 25–85 °Cwithout current adjustment. Relaxation oscillations up to ∼30 GHz have been realized indicating feasibility of 40 Gb/s signal transmission. PMID:21794188

  19. Micro Mirrors for High-speed Laser Deflection and Patterning

    NASA Astrophysics Data System (ADS)

    Schenk, Harald; Grahmann, Jan; Sandner, Thilo; Wagner, Michael; Dauderstädt, Ulrike; Schmidt, Jan-Uwe

    This paper focuses on high-speed optical MEMS Scanners and Micro Mirror Arrays. Devices supporting spot/pixel rateshigher than 10 Mpixel/s are considered and discussed regarding limits and possibilities to further improve speed and optical properties. Several variants of both types, developed by our group, are presented. Scanning Micro Mirrors with frequencies up to 100 kHz enable spot rates of up to 130 Mpixels / s at 650 nm. Bragg-coatings enable high power applications up to 20 W (beam ø2 mm). Challenges like static and dynamic mirror planariy are discussed. A 29-kHz-scanner for laser projection serves as application example. Highly parallel operated Micro Mirror Arrays extend pattern speed to 10 Gpixel / s including analog grey scaling. Irradiation tests prove stable operation of the mirrors at DUV. Prospects regarding optical planarity and high reflective coatings are discussed. By means of two examples, laser patterning of semiconductor masks and laser patterning of Printed Circuit Boards, properties of the spatial light modulators are presented. The two device classes are compared regarding spot/pixel rate and frequency. The comparison includes representative MEMS device examples from literature.

  20. Functionalised polyurethane for efficient laser micromachining

    NASA Astrophysics Data System (ADS)

    Brodie, G. W. J.; Kang, H.; MacMillan, F. J.; Jin, J.; Simpson, M. C.

    2017-02-01

    Pulsed laser ablation is a valuable tool that offers a much cleaner and more flexible etching process than conventional lithographic techniques. Although much research has been undertaken on commercially available polymers, many challenges still remain, including contamination by debris on the surface, a rough etched appearance and high ablation thresholds. Functionalizing polymers with a photosensitive group is a novel way and effective way to improve the efficiency of laser micromachining. In this study, several polyurethane films grafted with different concentrations of the chromophore anthracene have been synthesized which are specifically designed for 248 nm KrF excimer laser ablation. A series of lines etched with a changing number of pulses and fluences by the nanosecond laser were applied to each polyurethane film. The resultant ablation behaviours were studied through optical interference tomography and Scanning Electron Microscopy. The anthracene grafted polyurethanes showed a vast improvement in both edge quality and the presence of debris compared with the unmodified polyurethane. Under the same laser fluence and number of pulses the spots etched in the anthracene contained polyurethane show sharp depth profiles and smooth surfaces, whereas the spots etched in polyurethane without anthracene group grafted present rough cavities with debris according to the SEM images. The addition of a small amount of anthracene (1.47%) shows a reduction in ablation threshold from unmodified polyurethane showing that the desired effect can be achieved with very little modification to the polymer.

  1. Laser micromachining of semiconductors for photonics applications

    NASA Astrophysics Data System (ADS)

    Nantel, Marc; Yashkir, Yuri; Lee, Seong K.; Mugford, Chas; Hockley, Bernard S.

    2001-10-01

    For decades, precisely machining silicon has been critical for the success of the semiconductor industry. This has traditionally been done through wet chemical etching, but in the pursuit of integrating photonics devices on a single chip, other techniques are worth exploring. This quest opens up interest in finding a non-wet, non-contact, arbitrary-shape milling technique for silicon. In this paper, we present our latest work in the laser micromachining of silicon. A kilohertz-repetition-rate diode-pumped Nd:YLF laser (in infrared, green or ultraviolet modes) is focused on the surface of silicon wafers in a chlorine atmosphere for an enhanced magnitude and control of the etching rate. In the chlorine atmosphere, much less debris is deposited on the surface around the cut, sub-damage threshold machining is achieved for a better control of the etching depth, and etching rates ranging from 20-300,000 micron-cube/s have been measured. In particular, the use of an infrared laser beam is singled out, along with the advantages that it holds. Results of simulations highlight the particular characteristics of the various wavelength chosen for the machining.

  2. High Speed Laser with 100 Ghz Resonance Frequency

    DTIC Science & Technology

    2014-02-28

    practical limit occurs when the detuned master laser encounters the next-order laser modes (i.e. Fabry - Perot modes). Our current DFB slave laser...lasers and vertical- cavity surface-emitting lasers (VCSELs), showing the broad applicability of the technique and that the coupling Q (optical quality...Q-factor, and also increases as the injection power and optical frequency increase. Additionally, we show that lasers with very different cavity

  3. Laser balancing demonstration on a high-speed flexible rotor

    NASA Technical Reports Server (NTRS)

    Demuth, R. S.; Rio, R. A.; Fleming, D. P.

    1979-01-01

    This paper describes a flexible rotor system used for two-plane laser balancing and an experimental demonstration of the laser material removal method for balancing. A laboratory test rotor was modified to accept balancing corrections using a laser metal removal method while the rotor is at operating speed. The laser setup hardware required to balance the rotor using two correction planes is described. The test rig optical configuration and a neodymium glass laser were assembled and calibrated for material removal rates. Rotor amplitudes before and after balancing, trial and correction weights, rotor speed during operation of laser, and balancing time were documented. The rotor was balanced through the first bending critical speed using the laser material removal procedure to apply trial weights and correction weights without stopping the rotor.

  4. Laser balancing demonstration on a high-speed flexible rotor

    NASA Technical Reports Server (NTRS)

    Demuth, R. S.; Rio, R. A.; Fleming, D. P.

    1979-01-01

    This paper describes a flexible rotor system used for two-plane laser balancing and an experimental demonstration of the laser material removal method for balancing. A laboratory test rotor was modified to accept balancing corrections using a laser metal removal method while the rotor is at operating speed. The laser setup hardware required to balance the rotor using two correction planes is described. The test rig optical configuration and a neodymium glass laser were assembled and calibrated for material removal rates. Rotor amplitudes before and after balancing, trial and correction weights, rotor speed during operation of laser, and balancing time were documented. The rotor was balanced through the first bending critical speed using the laser material removal procedure to apply trial weights and correction weights without stopping the rotor.

  5. High-speed microvia formation with UV solid state lasers

    NASA Astrophysics Data System (ADS)

    Dunsky, Corey M.; Matsumoto, Hisashi; Simenson, Glenn

    2002-02-01

    Laser drilling has emerged in the last five years as the most widely accepted method of creating microvias in high- density electronic inter connect and chip packaging devices. Most commercially available laser drilling tools are currently based on one of two laser types: far-IR CO2 lasers and UV solid state lasers at 355 nm. While CO2 lasers are recognized for their high average power and drilling throughput, UV lasers are known for high precision material removal and their ability to drill the smallest vias, with diameters down to about 25-30 micrometers now achievable in production. This paper presents a historical overview of techniques for drilling microvias with UV solid state lasers. Blind and through via formation by percussion drilling, trepanning, spiralling, and image projection with a shaped beam are discussed. Advantages and range of applicability of each technique are summarized. Drivers of throughput scaling over the last five years are outlined and representative current-generation performance is presented.

  6. Study of high speed combustion flows by laser velocimetry

    NASA Technical Reports Server (NTRS)

    Schaefer, H. J.

    1984-01-01

    The feasibility of laser velocimetry in a high temperature jet was assessed in a model of an aircraft engine combustor. Experiments show that the problems encountered in measuring combustion flow can flow can be overcome by a carefully designed optical set-up and an appropriate signal processing and data acquisition system. Laser Doppler velocimetry provides useful information about coherent structures in hot free jets. The measurements agree with measurements in an isothermal jet.

  7. Laser micromachining of thin films for optoelectronic devices and packages

    NASA Astrophysics Data System (ADS)

    Moore, David F.; Williams, John A.; Hopcroft, Matthew A.; Boyle, Billy; He, Johnny H.; Syms, Richard R. A.

    2003-04-01

    Focused laser micromachining in an optical microscope system is used to prototype packages for optoelectronic devices and to investigate new materials with potential applications in packaging. Micromachined thin fims are proposed as mechanical components to locate fibers and other optical and electrical components on opto-assemblies. This paper reports prototype structures which are micromachined in silicon carbide to produce beams 5 μm thick by (1) laser cutting a track in a SiC coated Si wafer, (2) undercutting by anisotropic silicon etching using KOH in water, and (3) trimming if necessary with the laser system. This approach has the advantage of fast turn around and proof of concept. Mechanical test data are obtained from the prototype SiC beam package structures by testing with a stylus profilometer. The Youngs modulus obtained for chemical vapor deposited silicon carbide is 360 +/- 50 GPa indicating that it is a promising material for packaging applications.

  8. High speed ultrafast laser surface processing (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Mincuzzi, Girolamo; Kling, Rainer; Lopez, John; Hoenninger, Clemens; Audouard, Eric; Mottay, Eric P.

    2017-03-01

    Surface functionalization is a rapidly growing application for industrial ultrafast lasers. There is an increasing interest for high throughput surface processing, especially for texturing and engraving large manufacturing tools for different industrial fields such as injection molding, embossing and printing. Hydrophobic and hydrophilic surfaces, colored or deep black metal surfaces can now be industrially produced. The engraving speed is continuously improving following improvements in beam scanning technology and high average power industrial ultrafast lasers. Several tenths of MHz for the laser repetition rate and several hundreds of meter per second for the beam speed are available. More than 100 m/s scanning speed is then possible for laser surface structuring. But these surfaces are quite hard to produce since it is necessary to have a good compromise between high removal rate and high surface quality (low roughness, burr-free, narrow heat affected zone). In this work, we apply a simple engineering model based on the two temperature description of ultra-fast ablation to estimate key processing parameters. In particular, the pulse-to-pulse overlap which depends on the scanning velocity, the spot size, and the laser repetition rate all have to be adjusted to optimize the depth and roughness, otherwise heat accumulation and heat affected zone may appear. Optimal sequences of time and spatial superposition of pulses are determined and applied with a polygonal scanner. Ablation depth and processing speed obtained are compared with experimental results.

  9. Deep ultraviolet laser micromachining of novel fibre optic devices

    NASA Astrophysics Data System (ADS)

    Li, J.; Dou, J.; Herman, P. R.; Fricke-Begemann, T.; Ihlemann, J.; Marowsky, G.

    2007-04-01

    A deep ultraviolet F2 laser, with output at 157-nm wavelength, has been adopted for micro-shaping the end facets of single and multi-mode silica optical fibres. The high energy 7.9-eV photons drive strong interactions in the wide-bandgap silica fibres to enable the fabrication of surface-relief microstructures with high spatial resolution and smooth surface morphology. Diffraction gratings, focusing lenses, and Mach-Zehnder interferometric structures have been micromachined onto the cleaved-fibre facets and optically characterized. F2-laser micromachining is shown to be a rapid and facile means for direct-writing of novel infibre photonic components.

  10. Laser synchronized high-speed shutter for spectroscopic application

    DOEpatents

    Miles, Paul C.; Porter, Eldon L.; Prast, Thomas L.; Sunnarborg, Duane A.

    2002-01-01

    A fast mechanical shutter, based on rotating chopper wheels, has been designed and implemented to shutter the entrance slit of a spectrograph. This device enables an exposure time of 9 .mu.s to be achieved for a 0.8 mm wide spectrograph entrance slit, achieves 100% transmission in the open state, and an essentially infinite extinction ratio. The device further incorporates chopper wheel position sensing electronics to permit the synchronous triggering of a laser source.

  11. A summary of laser and microwave flow control in high-speed flows

    NASA Astrophysics Data System (ADS)

    Knight, D.

    2013-06-01

    Laser and microwave discharge in air has emerged as an effective method for flow control in high-speed flows. Computational and experimental research has demonstrated its capability for significant drag reduction and mitigation of adverse interactions in high-speed flows. The paper presents a summary of key computational and experimental studies performed at Rutgers University in collaboration with the Joint Institute for High Temperatures (Moscow, Russia) and St. Petersburg State University (St. Petersburg, Russia).

  12. High-speed laser communications in UAV scenarios

    NASA Astrophysics Data System (ADS)

    Griethe, Wolfgang; Gregory, Mark; Heine, Frank; Kämpfner, Hartmut

    2011-05-01

    Optical links, based on coherent homodyne detection and BPSK modulation with bidirectional data transmission of 5.6 Gbps over distances of about 5,000 km and BER of 10-8, have been sufficiently verified in space. The verification results show that this technology is suitable not only for space applications but also for applications in the troposphere. After a brief description of the Laser Communication Terminal (LCT) for space applications, the paper consequently discusses the future utilization of satellite-based optical data links for Beyond Line of Sight (BLOS) operations of High Altitude Long Endurance (HALE) Unmanned Aerial Vehicles (UAV). It is shown that the use of optical frequencies is the only logical consequence of an ever-increasing demand for bandwidth. In terms of Network Centric Warfare it is highly recommended that Unmanned Aircraft Systems (UAS) of the future should incorporate that technology which allows almost unlimited bandwidth. The advantages of optical communications especially for Intelligence, Surveillance and Reconnaissance (ISR) are underlined. Moreover, the preliminary design concept of an airborne laser communication terminal is described. Since optical bi-directional links have been tested between a LCT in space and a TESAT Optical Ground Station (OGS), preliminary analysis on tracking and BER performance and the impact of atmospheric disturbances on coherent links will be presented.

  13. Application of laser velocimetry to unsteady flows in large scale high speed tunnels

    NASA Technical Reports Server (NTRS)

    Owen, F. K.

    1983-01-01

    Flowfield measurements obtained in several large scale, high speed facilities are presented. Sampling bias and seeding problems are addressed and solutions are outlined. The laser velocimeter systems and data reduction procedures which were used in the experiments are also described. The work demonstrated the potential of the laser velocimeter for applications in other than closely controlled, smallscale laboratory situations.

  14. Mid-ultraviolet pulsed laser micromachining of SiC

    NASA Astrophysics Data System (ADS)

    Qi, Litao; Li, Mingxing; Lin, Haipeng; Hu, Jinping; Tang, Qingju; Liu, Chunsheng

    2014-11-01

    This paper provides an investigation of the ablation behavior of single crystal 4H-SiC and 6H-SiC wafer to improve the manufacturability and high-temperature performance of SiC using laser applications. 266nm pulsed laser micromachining of SiC was investigated. The purpose is to establish suitable laser parametric regime for the fabrication of high accuracy, high spatial resolution and thin diaphragms for high-temperature MEMS pressure sensor applications. Etch rate, ablation threshold and quality of micromachined features were evaluated. The governing ablation mechanisms, such as thermal vaporization, phase explosion, and photomechanical fragmentation, were correlated with the effects of pulse energy. The ablation threshold is obtained with ultraviolet pulsed laser ablation. The results suggested ultraviolet pulsed laser's potential for rapid manufacturing. Excellent quality of machined features with little collateral thermal damage was obtained in the lower pulse energy range. The leading material removal mechanisms under these conditions were discussed.

  15. A general high-speed laser drilling method for nonmetal thin material

    NASA Astrophysics Data System (ADS)

    Cai, Zhijian; Xu, Guangsheng; Xu, Zhou; Xu, Zhiqiang

    2013-05-01

    Many nonmetal film products, such as herbal plaster, medical adhesive tape and farm plastic film, require drilling dense small holes to enhance the permeability without affecting the appearance. For many medium and small enterprises, a low-cost, high-speed laser drilling machine with the ability of processing different kinds of nonmetal material is highly demanded. In this paper, we proposed a general purpose high-speed laser drilling method for micro-hole production on thin nonmetal film. The system utilizes a rotating polygonal mirror to perform high-speed laser scan, which is simpler and more efficient than the oscillating mirror scan. In this system, an array of closepacked paraboloid mirrors is mounted on the laser scan track to focus the high-power laser onto the material sheet, which could produce up to twenty holes in a single scan. The design of laser scan and focusing optics is optimized to obtain the best holes' quality, and the mirrors can be flexibly adjusted to get different drilling parameters. The use of rotating polygonal mirror scan and close-packed mirror array focusing greatly improves the drilling productivity to enable the machine producing thirty thousand holes per minute. With proper design, the hold uniformity can also get improved. In this paper, the detailed optical and mechanical design is illustrated, the high-speed laser drilling principle is introduced and the preliminary experimental results are presented.

  16. Real-Time Control of Ultrafast Laser Micromachining by Laser-Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Tong, Tao; Li, Jinggao; Longtin, Jon P.

    2004-03-01

    Ultrafast laser micromachining provides many advantages for precision micromachining. One challenging problem, however, particularly for multilayer and heterogeneous materials, is how to prevent a given material from being ablated, as ultrafast laser micromachining is generally material insensitive. We present a real-time feedback control system for an ultrafast laser micromachining system based on laser-induced breakdown spectroscopy (LIBS). The characteristics of ultrafast LIBS are reviewed and discussed so as to demonstrate the feasibility of the technique. Comparison methods to identify the material emission patterns are developed, and several of the resulting algorithms were implemented into a real-time computer control system. LIBS-controlled micromachining is demonstrated for the fabrication of microheater structures on thermal sprayed materials. Compared with a strictly passive machining process without any such feedback control, the LIBS-based system provides several advantages including less damage to the substrate layer, reduced machining time, and more-uniform machining features.

  17. CIGS thin-film solar module processing: case of high-speed laser scribing

    PubMed Central

    Gečys, Paulius; Markauskas, Edgaras; Nishiwaki, Shiro; Buecheler, Stephan; De Loor, Ronny; Burn, Andreas; Romano, Valerio; Račiukaitis, Gediminas

    2017-01-01

    In this paper, we investigate the laser processing of the CIGS thin-film solar cells in the case of the high-speed regime. The modern ultra-short pulsed laser was used exhibiting the pulse repetition rate of 1 MHz. Two main P3 scribing approaches were investigated – ablation of the full layer stack to expose the molybdenum back-contact, and removal of the front-contact only. The scribe quality was evaluated by SEM together with EDS spectrometer followed by electrical measurements. We also modelled the electrical behavior of a device at the mini-module scale taking into account the laser-induced damage. We demonstrated, that high-speed process at high laser pulse repetition rate induced thermal damage to the cell. However, the top-contact layer lift-off processing enabled us to reach 1.7 m/s scribing speed with a minimal device degradation. Also, we demonstrated the P3 processing in the ultra-high speed regime, where the scribing speed of 50 m/s was obtained. Finally, selected laser processes were tested in the case of mini-module scribing. Overall, we conclude, that the top-contact layer lift-off processing is the only reliable solution for high-speed P3 laser scribing, which can be implemented in the future terawatt-scale photovoltaic production facilities. PMID:28084403

  18. CIGS thin-film solar module processing: case of high-speed laser scribing.

    PubMed

    Gečys, Paulius; Markauskas, Edgaras; Nishiwaki, Shiro; Buecheler, Stephan; De Loor, Ronny; Burn, Andreas; Romano, Valerio; Račiukaitis, Gediminas

    2017-01-13

    In this paper, we investigate the laser processing of the CIGS thin-film solar cells in the case of the high-speed regime. The modern ultra-short pulsed laser was used exhibiting the pulse repetition rate of 1 MHz. Two main P3 scribing approaches were investigated - ablation of the full layer stack to expose the molybdenum back-contact, and removal of the front-contact only. The scribe quality was evaluated by SEM together with EDS spectrometer followed by electrical measurements. We also modelled the electrical behavior of a device at the mini-module scale taking into account the laser-induced damage. We demonstrated, that high-speed process at high laser pulse repetition rate induced thermal damage to the cell. However, the top-contact layer lift-off processing enabled us to reach 1.7 m/s scribing speed with a minimal device degradation. Also, we demonstrated the P3 processing in the ultra-high speed regime, where the scribing speed of 50 m/s was obtained. Finally, selected laser processes were tested in the case of mini-module scribing. Overall, we conclude, that the top-contact layer lift-off processing is the only reliable solution for high-speed P3 laser scribing, which can be implemented in the future terawatt-scale photovoltaic production facilities.

  19. CIGS thin-film solar module processing: case of high-speed laser scribing

    NASA Astrophysics Data System (ADS)

    Gečys, Paulius; Markauskas, Edgaras; Nishiwaki, Shiro; Buecheler, Stephan; de Loor, Ronny; Burn, Andreas; Romano, Valerio; Račiukaitis, Gediminas

    2017-01-01

    In this paper, we investigate the laser processing of the CIGS thin-film solar cells in the case of the high-speed regime. The modern ultra-short pulsed laser was used exhibiting the pulse repetition rate of 1 MHz. Two main P3 scribing approaches were investigated - ablation of the full layer stack to expose the molybdenum back-contact, and removal of the front-contact only. The scribe quality was evaluated by SEM together with EDS spectrometer followed by electrical measurements. We also modelled the electrical behavior of a device at the mini-module scale taking into account the laser-induced damage. We demonstrated, that high-speed process at high laser pulse repetition rate induced thermal damage to the cell. However, the top-contact layer lift-off processing enabled us to reach 1.7 m/s scribing speed with a minimal device degradation. Also, we demonstrated the P3 processing in the ultra-high speed regime, where the scribing speed of 50 m/s was obtained. Finally, selected laser processes were tested in the case of mini-module scribing. Overall, we conclude, that the top-contact layer lift-off processing is the only reliable solution for high-speed P3 laser scribing, which can be implemented in the future terawatt-scale photovoltaic production facilities.

  20. Parametric studies on the nanosecond laser micromachining of the materials

    NASA Astrophysics Data System (ADS)

    Tański, M.; Mizeraczyk, J.

    2016-12-01

    In this paper the results of an experimental studies on nanosecond laser micromachining of selected materials are presented. Tested materials were thin plates made of aluminium, silicon, stainless steel (AISI 304) and copper. Micromachining of those materials was carried out using a solid state laser with second harmonic generation λ = 532 nm and a pulse width of τ = 45 ns. The effect of laser drilling using single laser pulse and a burst of laser pulses, as well as laser cutting was studied. The influence of laser fluence on the diameter and morphology of a post ablation holes drilled with a single laser pulse was investigated. The ablation fluence threshold (Fth) of tested materials was experimentally determined. Also the drilling rate (average depth per single laser pulse) of holes drilled with a burst of laser pulses was determined for all tested materials. The studies of laser cutting process revealed that a groove depth increases with increasing average laser power and decreasing cutting speed. It was also found that depth of the laser cut grooves is a linear function of number of repetition of a cut. The quantitative influence of those parameters on the groove depth was investigated.

  1. Note: Lossless laser beam combiner employing a high-speed rotating half-wave plate.

    PubMed

    Yatsuka, E; Yamamoto, T; Hatae, T; Torimoto, K; Itami, K

    2017-07-01

    We have developed a laser beam combiner employing a high-speed rotating half-wave plate based on the specific requirements of the Thomson scattering measurement systems in the ITER. The polarization extinction ratio of the output beam may exceed 1000 and was maintained for more than 1 h via feedback control of the half-wave plate rotation speed. The pointing fluctuations introduced by rotating the half-wave plate were in the order of microradians. The high-speed rotating half-wave plate provides a lossless means of combining laser beams together with stable beam pointing.

  2. Note: Lossless laser beam combiner employing a high-speed rotating half-wave plate

    NASA Astrophysics Data System (ADS)

    Yatsuka, E.; Yamamoto, T.; Hatae, T.; Torimoto, K.; Itami, K.

    2017-07-01

    We have developed a laser beam combiner employing a high-speed rotating half-wave plate based on the specific requirements of the Thomson scattering measurement systems in the ITER. The polarization extinction ratio of the output beam may exceed 1000 and was maintained for more than 1 h via feedback control of the half-wave plate rotation speed. The pointing fluctuations introduced by rotating the half-wave plate were in the order of microradians. The high-speed rotating half-wave plate provides a lossless means of combining laser beams together with stable beam pointing.

  3. Pulpal temperature increases with Er:YAG laser and high-speed handpieces.

    PubMed

    Cavalcanti, Bruno Neves; Lage-Marques, José Luiz; Rode, Sigmar Mello

    2003-11-01

    During tooth preparation, both high-speed handpieces and lasers generate heat, which, if not controlled, can cause pulpal necrosis. The aim of this study was to compare temperature increases produced by a high-speed dental handpiece with those produced by a relatively new instrument, the Er:YAG (erbium: yttrium-aluminum-garnet) laser. Thirty bovine mandibular incisors were reduced to an enamel/dentin thickness of 2.5 mm. Class V preparations were completed to a depth of 2.0 mm, measured with a caliper or by a mark on the burs. A thermocouple was placed inside the pulp chamber to determine temperature increases (degrees C). Analysis was performed on the following groups (n=10): Group I, high-speed handpiece without water cooling, Group II, high-speed handpiece with water cooling (30 mL/min), and Group III, the noncontact Er:YAG laser (2.94 microm at 350 mJ/10 Hz) with water cooling (4.5 mL/min). The temperature increases were recorded by a computer linked to the thermocouples. The data were analyzed using the Kruskal-Wallis test. The Dunn multiple comparison test was used as post hoc test (alpha=.05). The average temperature rises were: 11.64 degrees C (+/- 4.35) for Group I, 0.96 degrees C (+/- 0.71) for Group II, and 2.69 degrees C (+/- 1.12) for Group III. There were no statistical differences between Groups II and III; both II and III differed from Group I significantly (P=.000 and P=.002, respectively). The preparations made with the high-speed and the laser instrument generated similar heat increases under water cooling. Water cooling was essential to avoid destructive temperature increases when using both the high-speed handpiece and laser.

  4. Dynamic characteristics of laser-induced vapor bubble formation in water based on high speed camera

    NASA Astrophysics Data System (ADS)

    Zhang, Xian-zeng; Guo, Wenqing; Zhan, Zhenlin; Xie, Shusen

    2013-08-01

    In clinical practice, laser ablation usually works under liquid environment such as water, blood or their mixture. Laser-induced vapor bubble or bubble formation and its consequent dynamics were believed to have important influence on tissue ablation. In the paper, the dynamic process of vapor bubble formation and consequently collapse induced by pulsed Ho:YAG laser in static water was investigated by using high-speed camera. The results showed that vapor channel / bubble can be produced with pulsed Ho:YAG laser, and the whole dynamic process of vapor bubble formation, pulsation and consequently collapse can be monitored by using high-speed camera. The dynamic characteristics of vapor bubble, such as pulsation period, the maximum depth and width were determined. The dependence of above dynamic parameters on incident radiant exposure was also presented. Based on which, the influence of vapor bubble on hard tissue ablation was discussed.

  5. Development and Fielding of High-Speed Laser Shadowgraphy for Electro-Magnetically Driven Cylindrical Implosions

    DTIC Science & Technology

    2013-06-01

    shockwave in a cylindrical geometry provides fundamental benchmarks used in the modeling of 1-D and 2-D hydrodynamic phenomena from high or solid...DEVELOPMENT AND FIELDING OF HIGH-SPEED LASER SHADOWGRAPHY FOR ELECTRO -MAGNETICALLY DRIVEN CYLINDRICAL IMPLOSIONS J. P. Roberts, G. Rodriguez...an electro -magnetically driven solid density liner implosion in Lucite is described. The laser shadowgraphy system utilizes an advanced high-energy

  6. High-speed off-axis holographic cinematography with a copper-vapor-pumped dye laser.

    PubMed

    Lauterborn, W; Judt, A; Schmitz, E

    1993-01-01

    A series of coherent light pulses is generated by pumping a dye laser with the pulsed output of a copper-vapor laser at rates of as much as 20 kHz. Holograms are recorded at this pulse rate on a rotating holographic plate. This technique of high-speed holographic cinematography is demonstrated by viewing the bubble filaments that appear in water under the action of a sound field of high intensity.

  7. Laser Micromachining and Information Discovery Using a Dual Beam Interferometry

    SciTech Connect

    Theppakuttaikomaraswamy, Senthil P.

    2001-01-01

    Lasers have proven to be among the most promising tools for micromachining because they can process features down to the size of the laser wavelength (smaller than 1 micrometer) and they provide a non-contact technology for machining. The demand for incorporating in-situ diagnostics technology into the micromachining environment is driven by the increasing need for producing micro-parts of high quality and accuracy. Laser interferometry can be used as an on-line monitoring tool and it is the aim of this work to enhance the understanding and application of Michelson interferometry principle for the in-situ diagnostics of the machining depth on the sub-micron and micron scales. micromachining is done on two different materials and a comprehensive investigation is done to control the width and depth of the machined feature. To control the width of the feature, laser micromachining is done on copper and a detailed analysis is performed. The objective of this experiment is to make a precision mask for sputtering with an array of holes on it using an Nd:YAG laser of 532 nm wavelength. The diameter of the hole is 50 μm and the spacing between holes (the distance between the centers) is 100 μm. Michelson interferometer is integrated with a laser machining system to control the depth of machining. An excimer laser of 308 nm wavelength is used for micromachining. A He-Ne laser of 632.8 nm wavelength is used as the light source for the interferometer. Interference patterns are created due to the change in the path length between the two interferometer arms. The machined depth information is obtained from the interference patterns on an oscilloscope detected by a photodiode. To compare the predicted depth by the interferometer with the true machining depth, a surface profilometer is used to measure the actual machining depth on the silicon. It is observed that the depths of machining obtained by the surface profile measurement are in accordance with the interferometer

  8. High-speed photography of Er: YAG laser ablation in fluid. Implication for laser vitreous surgery.

    PubMed

    Lin, C P; Stern, D; Puliafito, C A

    1990-12-01

    The mechanism of Er:YAG laser-induced long-range damage in intraocular surgery was investigated using high-speed photography. A short pulse of 2.94-microns radiation delivered by an optical fiber into an aqueous medium causes rapid localized heating and vaporization and creates a bubble at the tip of the fiber. The size of the bubble depends on the pulse energy and is about 1 mm at 1 mJ. The shape of the bubble has multiple lobes, which can be attributed to the spiky output of the laser pulse. The expanding bubble can cause thermal and mechanical damage to tissues. In addition, laser spikes propagating through the bubble can strike and damage tissue on the distal side of the bubble. In both mechanisms the damage zone approximates the bubble size and can be greater than 1 mm, ie, 1000 times the steady-state absorption length of water at 2.94 microns. The authors discuss ways to reduce the damage zone by bubble confinement.

  9. Small high-speed dynamic target at close range laser active imaging system

    NASA Astrophysics Data System (ADS)

    Yao, Jun; Wang, Du-yue; Zhang, Zheng; Zhang, Yue; Dai, Qin

    2016-11-01

    In the shooting range measuring, all-weather, high speed, unattended, the new concepts such as the remote control is gradually applied. In this paper, a new type of low cost range measurement system, using FPGA + MCU as electronic control system of laser active illumination and high-speed CMOS camera, data to the rear zone by using optical fiber communications, transmission and realizes the remote control of unmanned, due to the low cost of front-end equipment, can be used as consumables replacement at any time, combined with distributed layout principle, can maximum limit close to the measured with mutilate ability goal, thus to achieve the goal of small high-speed dynamic imaging from close range.

  10. Micromachining of a piezocomposite transducer using a copper vapor laser.

    PubMed

    Farlow, R; Galbraith, W; Knowles, M; Hayward, G

    2001-05-01

    A 1-3 piezocomposite transducer with front face dimensions of 2 x 2 mm has been micromachined using a copper vapor laser. The device consists of PZT5A piezoceramic pillars with a 65-micron pitch suspended in a low viscosity thermosetting polymer. The kerf width is 13 microns, and the transducer thickness is 170 microns, making the device suitable for ultrasonic reception at frequencies close to 10 MHz.

  11. High-speed demodulation system of identical weak FBGs based on FDML wavelength swept laser

    NASA Astrophysics Data System (ADS)

    Wang, Yiming; Liu, Quan; Wang, Honghai; Hu, Chenchen; Zhang, Chun; Li, Zhengying

    2017-04-01

    An identical weak reflection FBGs demodulation system based on a FDML laser is proposed. The laser is developed to output a continuous wavelength-swept spectrum in the scanning frequency of 120 kHz over a spectral range of more than 10nm at 1.54 μm. Based on this high-speed wavelength-swept light and the optical transmission delay effect, the demodulation system obtains the location and wavelength information of all identical weak FBGs by the reflected spectrum within each scanning cycle. By accessing to a high-speed FPGA processing module, continuous demodulation of 120 kHz is realized. The system breakthroughs the bandwidth of the laser to expand the sensors capacity and greatly improves the demodulation speed of a TDM sensing network. The experiments show the system can distinguish and demodulate the identical weak FBGs and measure the 4 kHz vibration at 120 kHz demodulation speed.

  12. A high-speed full-field profilometry with coded laser strips projection

    NASA Astrophysics Data System (ADS)

    Zhang, Guanliang; Zhou, Xiang; Jin, Rui; Xu, Changda; Li, Dong

    2017-06-01

    Line structure light measurement needs accurate mechanical movement device and high -frame-rate camera, which is difficult to realize. We propose a high-speed full-field profilometry to solve these difficult ies, using coded laser strips projected by a MEMS scanning mirror. The mirror could take place of the mechanical movement device with its high speed and accurate. Besides, a method with gray code and color code is used to decrease the frames number of projection, retaining the advantage of line structure light measurement. In the experiment, we use a laser MEMS scanner and two color cameras. The laser MEMS scanner projects coded stripes, with two color cameras collecting the modulated pattern on the measured object. The color cameras compose a stereo vision system so that the three-dimensional data is reconstructed according to triangulation.

  13. Influences of carrier diffusion and radial mode field pattern on high speed characteristics for microring lasers

    SciTech Connect

    Lv, Xiao-Meng; Huang, Yong-Zhen Yang, Yue-De; Zou, Ling-Xiu; Long, Heng; Liu, Bo-Wen; Xiao, Jin-Long; Du, Yun

    2014-04-21

    High-speed directly modulated microlasers are potential light sources for on-chip optical interconnection and photonic integrated circuits. In this Letter, dynamic characteristics are studied for microring lasers by rate equation analysis considering radial carrier hole burning and diffusion and experimentally. The coupled modes with a wide radial field pattern and the injection current focused in the edge area of microring resonator can greatly improve the high speed response curve due to the less carrier hole burning. The small-signal response curves of a microring laser connected with an output waveguide exhibit a larger 3 dB bandwidth and smaller roll-off at low frequency than that of the microdisk laser with the same radius of 15 μm, which accords with the simulation results.

  14. The temperature measurement research for high-speed flow based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Di, Yue; Jin, Yi; Jiang, Hong-liang; Zhai, Chao

    2013-09-01

    Due to the particularity of the high-speed flow, in order to accurately obtain its' temperature, the measurement system should has some characteristics of not interfereing with the flow, non-contact measurement and high time resolution. The traditional measurement method cannot meet the above requirements, however the measurement method based on tunable diode laser absorption spectroscopy (TDLAS) technology can meet the requirements for high-speed flow temperature measurement. When the near-infared light of a specific frequency is through the media to be measured, it will be absorbed by the water vapor molecules and then the transmission light intensity is detected by the detector. The temperature of the water vapor which is also the high-speed flow temperature, can be accurately obtained by the Beer-Lambert law. This paper focused on the research of absorption spectrum method for high speed flow temperature measurement with the scope of 250K-500K. Firstly, spectral line selection method for low temperature measurement of high-speed flow is discussed. Selected absorption lines should be isolated and have a high peak absorption within the range of 250-500K, at the same time the interference of the other lines should be avoided, so that a high measurement accuracy can be obtained. According to the near-infrared absorption spectra characteristics of water vapor, four absorption lines at the near 1395 nm and 1409 nm are selected. Secondly, a system for the temperature measurement of the water vapor in the high-speed flow is established. Room temperature are measured through two methods, direct absorption spectroscopy (DAS) and wavelength modulation spectroscopy (WMS) ,the results show that this system can realize on-line measurement of the temperature and the measurement error is about 3%. Finally, the system will be used for temperature measurement of the high-speed flow in the shock tunnel, its feasibility of measurement is analyzed.

  15. Vascular tissue engineering by computer-aided laser micromachining.

    PubMed

    Doraiswamy, Anand; Narayan, Roger J

    2010-04-28

    Many conventional technologies for fabricating tissue engineering scaffolds are not suitable for fabricating scaffolds with patient-specific attributes. For example, many conventional technologies for fabricating tissue engineering scaffolds do not provide control over overall scaffold geometry or over cell position within the scaffold. In this study, the use of computer-aided laser micromachining to create scaffolds for vascular tissue networks was investigated. Computer-aided laser micromachining was used to construct patterned surfaces in agarose or in silicon, which were used for differential adherence and growth of cells into vascular tissue networks. Concentric three-ring structures were fabricated on agarose hydrogel substrates, in which the inner ring contained human aortic endothelial cells, the middle ring contained HA587 human elastin and the outer ring contained human aortic vascular smooth muscle cells. Basement membrane matrix containing vascular endothelial growth factor and heparin was to promote proliferation of human aortic endothelial cells within the vascular tissue networks. Computer-aided laser micromachining provides a unique approach to fabricate small-diameter blood vessels for bypass surgery as well as other artificial tissues with complex geometries.

  16. Laser beam hardening of cast carbon steels, plain cast irons, and high-speed steels

    NASA Astrophysics Data System (ADS)

    Bylica, Andrzej; Adamiak, Stanislaw; Bochnowski, Wojciech; Dziedzic, Andrzej

    2000-11-01

    The examinations of the structure, hardness and abrasion resistance of surface layer of Fe-C alloys having the contents of carbon up to 4% and high-speed steel: 6-5-2, 4- 4-2-5+C after laser hardening are presented in the paper. They are compared with the properties obtained after conventional hardening. Laser of impulse operation - YAG:Nd and of continuous operation - CO2 were used. Analysis of structure was carried out based on metallographic and fractographic examinations as well as on X-ray properties, parameters of laser and conventional heat treatment of steels were defined.

  17. Laser Beam MicroMachining (LBMM) - A review

    NASA Astrophysics Data System (ADS)

    Mishra, Sanjay; Yadava, Vinod

    2015-10-01

    The use of short and ultrashort laser pulses for micromachining application is an emerging technology. Laser Beam MicroMachining (LBMM) has revolutionized many industries by providing innovative solutions in numerous industrial micro-engineering applications. High-intensity short or ultrashort laser pulses are powerful thermal energy source for creating micro-features in wide range of materials. These lasers can precisely ablate various types of materials with little or no collateral damage. An overview of LBMM is given so that we can obtain a current view of capabilities and tradeoffs associated with LBMM of sub-micron size. The fundamental understanding of ultrafast laser ablation process has been elucidated and the various research activities performed with nanosecond, picosecond and femtosecond, lasers have been discussed to understand the physical mechanisms and the critical experimental parameters involved in the LBMM. The critical analysis of various theoretical and experimental models used to describe the performance analysis of LBMM has been elaborated so that we can identify the relevant principles underlying the process.

  18. Precision Control Module For UV Laser 3D Micromachining

    NASA Astrophysics Data System (ADS)

    Wu, Wen-Hong; Hung, Min-Wei; Chang, Chun-Li

    2011-01-01

    UV laser has been widely used in various micromachining such as micro-scribing or patterning processing. At present, most of the semiconductors, LEDs, photovoltaic solar panels and touch panels industries need the UV laser processing system. However, most of the UV laser processing applications in the industries utilize two dimensional (2D) plane processing. And there are tremendous business opportunities that can be developed, such as three dimensional (3D) structures of micro-electromechanical (MEMS) sensor or the precision depth control of indium tin oxide (ITO) thin films edge insulation in touch panels. This research aims to develop a UV laser 3D micromachining module that can create the novel applications for industries. By special designed beam expender in optical system, the focal point of UV laser can be adjusted quickly and accurately through the optical path control lens of laser beam expender optical system. Furthermore, the integrated software for galvanometric scanner and focal point adjustment mechanism is developed as well, so as to carry out the precise 3D microstructure machining.

  19. Micromachining of polydimethylsiloxane induced by laser plasma EUV light

    NASA Astrophysics Data System (ADS)

    Torii, S.; Makimura, T.; Okazaki, K.; Nakamura, D.; Takahashi, A.; Okada, T.; Niino, H.; Murakami, K.

    2011-06-01

    Polydimethylsiloxane (PDMS) is fundamental materials in the field of biotechnology. Because of its biocompatibility, microfabricated PDMS sheets are applied to micro-reactors and microchips for cell culture. Conventionally, the microstructures were fabricated by means of cast or imprint using molds, however it is difficult to fabricate the structures at high aspect ratios such as through-holes/vertical channels. The fabrication of the high-aspect structures would enable us to stack sheets to realize 3D fluidic circuits. In order to achieve the micromachining, direct photo-ablation by short wavelength light is promising. In the previous works, we investigated ablation of transparent materials such as silica glass and poly(methyl methacrylate) induced by irradiation with laser plasma EUV light. We achieved smooth and fine nanomachining. In this work, we applied our technique to PDMS micromachining. We condensed the EUV light onto PDMS surfaces at high power density up to 108 W/cm2 using a Au coated ellipsoidal mirror. We found that PDMS sheet was ablated at a rate up to 440 nm/shot. It should be emphasized that through hole with a diameter of 1 μm was fabricated in a PDMS sheet with a thickness of 4 μm. Thus we demonstrated the micromachining of PDMS sheets using laser plasma EUV light.

  20. Applications of laser lithography on oxide film to titanium micromachining

    NASA Astrophysics Data System (ADS)

    Chauvy, P.-F.; Hoffmann, P.; Landolt, D.

    2003-03-01

    Due to its good biocompatibility titanium is widely used for dental and orthopaedics implants and for biomedical microsystems. For these applications one needs specific micromachining methods. A new four-step method for electrochemical micromachining of titanium is presented here, which implies anodic oxidation, Excimer laser sensitising irradiation, anodic dissolution, and ultrasonic cleaning. The method is applied to the fabrication of two 3D model structures, surface structuring of a cylinder and machining of a complex two-level architecture. The absence of debris and of a heat affected zone as well as the resulting surface smoothness are the main advantages of the process. Ways to improve the still limited processing speed are discussed with regards to potential applications.

  1. Laser micromachining of chemically altered polymers

    SciTech Connect

    Lippert, T.

    1998-08-01

    During the last decade laser processing of polymers has become an important field of applied and fundamental research. One of the most promising proposals, to use laser ablation as dry etching technique in photolithography, has not yet become an industrial application. Many disadvantages of laser ablation, compared to conventional photolithography, are the result of the use of standard polymers. These polymers are designed for totally different applications, but are compared to the highly specialized photoresist. A new approach to laser polymer ablation will be described; the development of polymers, specially designed for high resolution laser ablation. These polymers have photolabile groups in the polymer backbone, which decompose upon laser irradiation or standard polymers are modified for ablation at a specific irradiation wavelength. The absorption maximum can be tailored for specific laser emissino lines, e.g. 351, 308 and 248 nm lines of excimer lasers. The authors show that with this approach many problems associated with the application of laser ablation for photolithography can be solved. The mechanism of ablation for these photopolymers is photochemical, whereas for most of the standard polymers this mechanism is photothermal. The photochemical decomposition mechanism results in high resolution ablation with no thermal damage at the edges of the etched structures. In addition there are no redeposited ablation products or surface modifications of the polymer after ablation.

  2. Application of COTS high-speed 980-nm pump laser diode and driver for free-space laser communication terminal

    NASA Astrophysics Data System (ADS)

    Chan, Eric Y.; Adams, Jeff C.; Saint Clair, Jonathan M.; Morrison, Kenneth A.; Sosa, Martin

    1999-06-01

    In our Photonics West 98 paper, we presented our study results on using commercially available 860 nm high power laser diodes and high-speed laser driver for free-space laser communication terminal application. We demonstrated the feasibility of a free space laser communication link using a junction-up 860 nm high power laser diode driven by a high current laser driver from Hytek Microsystems up to 622 Mb/s. Recent development in high speed InGaAs/GaAs strained layer quantum well (SLQW) laser at 980 nm has provided an additional design option for a laser communication terminal. The advantages of using the 980 nm laser are: (1) WDM market in the telecom industry has created a volume demand for the 980 nm pump lasers. The future cost of 980 nm lasers is expected to be lower due to the economy of scale. (2) In our previous publications, we have demonstrated CW operation of strained layer QW laser at temperature higher than 200 degree(s)C. There is a potential for this type of laser diode to operate in a much harsher and higher temperature environment, and (3) 980 nm pump laser has output power comparable to high power 860 nm laser diodes. In this paper, we will present the high data rate characteristics of a high-speed 980 nm (SLQW) pump laser. Using commercial-off-the-shelf laser drivers we will demonstrate the laser transmitter system characteristics from 622 Mb/s to 3 Gb/s. Detail experimental results on bit- error-rate measurement for a 980 nm device will be presented.

  3. Birefringent vertical cavity surface-emitting lasers: toward high-speed spin-lasers

    NASA Astrophysics Data System (ADS)

    Gerhardt, Nils C.; Lindemann, Markus; Pusch, Tobias; Michalzik, Rainer; Hofmann, Martin R.

    2016-04-01

    Spin-polarized vertical-cavity surface-emitting lasers (spin-VCSELs) provide novel opportunities to overcome several limitations of conventional, purely charge-based semiconductor lasers. Presumably the highest potential lies in the spin-VCSEL's capability for ultrafast spin and polarization dynamics which can be significantly faster than the intensity dynamics in conventional devices. By injecting spin-polarized carriers, these coupled spin-photon dynamics can be controlled and utilized for high-speed applications. While relaxation oscillations provide insights in the speed and direct modulation bandwidth of conventional devices, resonance oscillations in the circular polarization degree step in for the spin and polarization dynamics in spin-VCSELs. These polarization oscillations can be generated using pulsed spin injection and achieve much higher frequencies than the conventional intensity relaxation oscillations in these devices. Furthermore polarization oscillations can be switched on and off and it is possible to generate short polarization pulses, which may represent an information unit in polarization-based optical communication. The frequency of polarization oscillations is mainly determined by the birefringence-induced mode splitting between both orthogonal linearly polarized laser modes. Thus the polarization modulation bandwidth of spin-VCSELs can be increased by adding a high amount of birefringence to the cavity, for example by incorporating mechanical strain. Using this technique, we could demonstrate tunable polarization oscillations from 10 to 40 GHz in AlGaAs-based 850nm VCSELs recently. Furthermore a birefringence-induced mode splitting of more than 250 GHz could be demonstrated experimentally. Provided that this potential for ultrafast dynamics can be fully exploited, birefringent spin-VCSELs are ideal devices for fast short-haul optical interconnects. In this paper we review our recent progress on polarization dynamics of birefringent spin

  4. Study of cavitation bubble dynamics during Ho:YAG laser lithotripsy by high-speed camera

    NASA Astrophysics Data System (ADS)

    Zhang, Jian J.; Xuan, Jason R.; Yu, Honggang; Devincentis, Dennis

    2016-02-01

    Although laser lithotripsy is now the preferred treatment option for urolithiasis, the mechanism of laser pulse induced calculus damage is still not fully understood. This is because the process of laser pulse induced calculus damage involves quite a few physical and chemical processes and their time-scales are very short (down to sub micro second level). For laser lithotripsy, the laser pulse induced impact by energy flow can be summarized as: Photon energy in the laser pulse --> photon absorption generated heat in the water liquid and vapor (super heat water or plasma effect) --> shock wave (Bow shock, acoustic wave) --> cavitation bubble dynamics (oscillation, and center of bubble movement , super heat water at collapse, sonoluminscence) --> calculus damage and motion (calculus heat up, spallation/melt of stone, breaking of mechanical/chemical bond, debris ejection, and retropulsion of remaining calculus body). Cavitation bubble dynamics is the center piece of the physical processes that links the whole energy flow chain from laser pulse to calculus damage. In this study, cavitation bubble dynamics was investigated by a high-speed camera and a needle hydrophone. A commercialized, pulsed Ho:YAG laser at 2.1 mu;m, StoneLightTM 30, with pulse energy from 0.5J up to 3.0 J, and pulse width from 150 mu;s up to 800 μs, was used as laser pulse source. The fiber used in the investigation is SureFlexTM fiber, Model S-LLF365, a 365 um core diameter fiber. A high-speed camera with frame rate up to 1 million fps was used in this study. The results revealed the cavitation bubble dynamics (oscillation and center of bubble movement) by laser pulse at different energy level and pulse width. More detailed investigation on bubble dynamics by different type of laser, the relationship between cavitation bubble dynamics and calculus damage (fragmentation/dusting) will be conducted as a future study.

  5. Integration and test of high-speed transmitter electronics for free-space laser communications

    NASA Technical Reports Server (NTRS)

    Soni, Nitin J.; Lizanich, Paul J.

    1994-01-01

    The NASA Lewis Research Center in Cleveland, Ohio, has developed the electronics for a free-space, direct-detection laser communications system demonstration. Under the High-Speed Laser Integrated Terminal Electronics (Hi-LITE) Project, NASA Lewis has built a prototype full-duplex, dual-channel electronics transmitter and receiver operating at 325 megabit S per second (Mbps) per channel and using quaternary pulse-position modulation (QPPM). This paper describes the integration and testing of the transmitter portion for future application in free-space, direct-detection laser communications. A companion paper reviews the receiver portion of the prototype electronics. Minor modifications to the transmitter were made since the initial report on the entire system, and this paper addresses them. The digital electronics are implemented in gallium arsenide integrated circuits mounted on prototype boards. The fabrication and implementation issues related to these high-speed devices are discussed. The transmitter's test results are documented, and its functionality is verified by exercising all modes of operation. Various testing issues pertaining to high-speed circuits are addressed. A description of the transmitter electronics packaging concludes the paper.

  6. High-speed identical weak fiber Bragg grating interrogation system using DFB laser

    NASA Astrophysics Data System (ADS)

    Zhang, Chun; Liu, Siqi; Wang, Yiming; Liu, Jiapei; Wang, Honghai; Li, Zhengying

    2017-04-01

    A high-speed fiber Bragg grating (FBG) interrogation system is realized by using the high-speed sweep characteristic of Distributed feedback (DFB) laser to constitute a high-speed wavelength-swept laser. To solve the problem of narrow scanning width of the DFB laser and low reuse capacity of the system, the method of building a time division multiplexing (TDM) sensor network with identical weak fiber Bragg grating is proposed. By using the transmission delay of light between the gratings to separate the grating reflection spectrum in time-domain and demodulating the reflection scanning spectrum of each grating to realize the wavelength demodulation. Experimental results show that, under a constant interrogation frequency on 100kHz of the system, 10 identical weak FBGs with the center wavelength of 1553.7nm and reflectivity of 1% have achieved demodulation in a single fiber. And within the temperature range from 25°C to 79°C the linearity of each FBG's center wavelength varying with the temperature reaches 0.99 .

  7. High power CO2 laser development with AOM integration for ultra high-speed pulses

    NASA Astrophysics Data System (ADS)

    Bohrer, Markus; Vaupel, Matthias; Nirnberger, Robert; Weinberger, Bernhard; Jamalieh, Murad

    2017-01-01

    There is a 500 billion USD world market for packaging expected to grow to a trillion in 2030. Austria plays an important role world wide for high speed laser engraving applications — especially when it comes to high end solutions. Such high end solutions are fundamental for the production of print forms for the packaging and decorating industry (e. g. cans). They are additionally used for security applications (e. g. for printing banknotes), for the textile printing industry and for creating embossing forms (e. g. for the production of dashboards in the automotive industry). High speed, high precision laser engraving needs laser resonators with very stable laser beams (400 - 800W) especially in combination with AOMs. Based upon a unique carbon fiber structure - stable within the sub-micrometer range - a new resonator has been developed, accompanied by most recent thermo-mechanical FEM calculations. The resulting beam is evaluated on an automated optical bench using hexapods, allowing to optimize the complete beam path with collimators and AOM. The major steps related to laser engraving of dry offset printing plates during the full workflow from the artists design to the printed result on an aluminum can is presented in this paper as well as laser characteristics, AOM integration and correlative CLSM and SEM investigation of the results.

  8. Hydrodynamic Instability in High-speed Direct Laser Deposition for Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Turichin, Gleb; Zemlyakov, Evgeny; Klimova, Olga; Babkin, Konstantin

    High speed direct laser deposition, when product forms from metal powder, transferred by gas-powder jet, supplied coaxially or non-coaxially to focused laser beam, in one of most prospective additive technologies for production parts for aircraft engines. The limit of process productivity is connected with development of hydrodynamic instability of the melt pool in conditions of high power laser action and material supply by gas-powder jet. Theoretical analysis and experiments allowed clarified a physical nature of instability appearance, determine a stability conditions and invent a methods which allow avoid instability in deposition process. Nozzles for direct laser deposition, designed with consideration of stability conditions, allow get a level of process productivity more then 2 kg/h. The developed technology of deposition and technological equipment, based on high power fiber laser, has been used for manufacturing of parts for "high temperature" unit of aircraft engine.

  9. High-speed x-ray radiographic measurement of laser-driven hydrodynamic instability

    NASA Astrophysics Data System (ADS)

    Shiraga, Hiroyuki; Azechi, Hiroshi; Nakai, Mitsuo; Shigemori, Keisuke; Nishikino, Masaharu; Sakaiya, Tatsuhiro; Fujioka, Shinsuke; Tamari, Yohei; Yamanaka, Tatsuhiko

    2003-07-01

    Hydrodynamic instability in laser-irradiated targets have been investigated in detail by using ultra high-speed x-ray radiographic technique. Recently developed high-resolution x-ray imaging for laser-driven Rayleigh-Taylor (RT) instability experiments as well as data including RT growth rate, ablation density and plasma density profile are desribed. Results are of great importance for comprehensive understanding of the dispersion relation of the laser-driven RT instability. Especially, direct observation of the ablation density was first achieved with temporal and spatial resolutions of 100 ps and 3 μm, respectively. Imaging techniques includes x-ray Moire imaging, x-ray penumbral imaging and Fresnel phase zone plate imaging coupled with x-ray streak cameras or x-ray CCD cameras. Experiments were performed by using Gekko-XII/HIPER laser system at the Institute of Laser Engineering, Osaka University.

  10. Vertical cavity surface-emitting laser scanning cytometer for high speed analysis of cells

    SciTech Connect

    Gourley, P.L.; McDonald, A.E.; Gourley, M.F.

    1995-12-31

    We have constructed a new semiconductor laser device that may be useful in high speed characterization of cell morphology for diagnosis of disease. This laser device has critical advantages over conventional cell fluorescence detection methods since it provides intense, monochromatic, low-divergence fight signals that are emitted from lasing modes confined by a cell. Further, the device integrates biological structures with semiconductor materials at the wafer level to reduce device size and simplify cell preparation. In this paper we discuss operational characteristics of the prototype cytometer and present preliminary data for blood cells and dielectric spheres.

  11. Pulsed laser triggered high speed microfluidic fluorescence activated cell sorter†‡

    PubMed Central

    Wu, Ting-Hsiang; Chen, Yue; Park, Sung-Yong; Hong, Jason; Teslaa, Tara; Zhong, Jiang F.; Di Carlo, Dino; Teitell, Michael A.

    2014-01-01

    We report a high speed and high purity pulsed laser triggered fluorescence activated cell sorter (PLACS) with a sorting throughput up to 20 000 mammalian cells s−1 with 37% sorting purity, 90% cell viability in enrichment mode, and >90% purity in high purity mode at 1500 cells s−1 or 3000 beads s−1. Fast switching (30 μs) and a small perturbation volume (~90 pL) is achieved by a unique sorting mechanism in which explosive vapor bubbles are generated using focused laser pulses in a single layer microfluidic PDMS channel. PMID:22361780

  12. New high-speed photography technique for observation of fluid flow in laser welding

    NASA Astrophysics Data System (ADS)

    Eriksson, Ingemar; Gren, Per; Powell, John; Kaplan, Alexander F. H.

    2010-10-01

    Recent developments in digital high-speed photography allow us to directly observe the surface topology and flow conditions of the melt surface inside a laser evaporated capillary. Such capillaries (known as keyholes) are a central feature of deep penetration laser welding. For the first time, it can be confirmed that the liquid capillary surface has a rippled, complex topology, indicative of subsurface turbulent flow. Manipulation of the raw data also provides quantitative measurements of the vertical fluid flow from the top to the bottom of the keyhole.

  13. Laser micromachining for fatigue and fracture mechanics applications

    NASA Astrophysics Data System (ADS)

    Gupta, M. C.; Li, B.; Gadag, S.; Chou, K. C.

    2010-04-01

    A laser micromachining (LMM) method to initiate flaws for fatigue and fracture mechanics applications is successfully demonstrated. Dynamic response of moving energy pulses during LMM of titanium alloy (Ti-3.5Al-2.5V) was numerically simulated by an integrated energy approach using temperature-dependent thermophysical properties and 3D heat transfer code. Stress and strain analyses were performed for a titanium tube of 9.53 mm outer diameter (OD) and 0.81 mm wall thickness (WT) with a 0.23 mm deep and 1.83-mm-long longitudinal laser micro-machined notch, using nonlinear finite element analysis (FEA). For comparison, an electric-discharge-machined (EDM) notched tube with the same notch profile as the laser-prepared tube was also investigated. The calculated hoop stress and strain amplitudes at the notch root of the EDM-prepared tube were approximately 64% and 63% of the stress and strain amplitudes in the laser-prepared tube, respectively, when two tubes were subjected to inner pressures for R ratio of 0.03 and Δ P=45, 50, and 55 MPa. Fatigue life due to crack initiation process can be minimized using LMM method. The described LMM method is, therefore, more appropriate than EDM for accomplishing flaw formation to study fatigue and fracture behavior of various materials.

  14. Primary research on image of plasma in CO II laser welding with high-speed photography

    NASA Astrophysics Data System (ADS)

    Liu, Jinhe; Ma, Licai; Xie, Yaozheng; Zhang, Yong

    2006-02-01

    In this paper the image by high-speed photography of plasma in CO II laser welding is studied including the area of these images, the change rate of these images, the isogray line of the image and the maximal variation of the image gray. The used laser is RS850 made in German and the high-speed photography is NAC-10 made in Japan. The weld material is low carbon steel. The welding parameters include laser power 4KW, welding speed 1.2m/min, shielding gas Helium, Helium flow rate 11L/min. The parameters for high-speed photography are as exposure time 1/5000 of second, shoot frequency 1000 frame/s. According to the analyses the main conclusion as follows: In the experiment, the values of gray of these images cover from 40 to 255. The area of the plasma is oscillation and the average frequency of the oscillation is about 300Hz. The laser welding plasma can be divided to three parts: periphery, smoothness and core from the external to inner. The isogray line of the periphery is very irregular because of shocking of the shielding gas and the metal spatter. In the core region, the thermal motion of the electrons is violent, so there is lots of little division with complex shape. The gap of isogrey line in the periphery region and core region are larger than it in the smoothing region. The isogrey lines of the image in the melting pool link with the isogray line of the image of the laser welding plasma, so it can be used to checking the temperature field each other. There exits an isothermal kernel in the core region.

  15. Q-Switched Nd: YAG Laser Micro-Machining System

    SciTech Connect

    Messaoud, S.; Allam, A.; Siserir, F.; Bouceta, Y.; Kerdja, T.; Ouadjaout, D.

    2008-09-23

    In this paper, we present the design of a low cost Q-switched Nd: YAG laser micro-machining system for photo masks fabrication. It consists of: Nd:YAG laser source, beam delivery system, X-Y table, PC, The CCD camera and TV monitor. The synchronization between the laser source and the X-Y table is realised by NI PCI-7342, the two axis MID-7602 and LabVIEW based program. The first step of this work consists of engraving continuous and discontinuous lines on a thin film metal with a 100 {mu}m resolution by using the YG 980 Quantel Q-switched Nd:YAG laser.

  16. A High Speed Calibration Method for Laser Positioner by Constant Velocity Scanning

    NASA Astrophysics Data System (ADS)

    Ono, Hiroyuki

    This paper describes a high speed calibration method for laser positioner by scanning work area under constant velocity. Laser positioner consists of sinusoidal laser encoder, DC motor and the controller. The encoder has diffraction grating scale and laser optics. It generates sine and cosine outputs according to the travel distance. Qualities of the scale and the optics contribute to the fluctuation of output signal amplitude, DC offset and relative phase. First, the controller collects the output data under constant velocity of 4 samples per 1 sine wave length. The parameter can be estimated by simplified discrete Fourier transform method. Calibration data are collected every quarter sine wave length over all positioner work area. The result is stored in the table then referred by the controller in real time operation. Experiment results are also reported for HDD servo track writer application.

  17. Effect of light backscattering on high-speed modulation performance in strongly injection-locked unidirectional semiconductor ring lasers

    NASA Astrophysics Data System (ADS)

    Smolyakov, Gennady A.; Osinski, Marek

    2014-03-01

    Greatly enhanced high-speed modulation performance has been recently predicted in numerical calculations for a novel injection-locking scheme involving a DBR or DFB master laser monolithically integrated with a unidirectional semiconductor microring laser. In this work, we investigate the effect of light backscattering between the two counterpropagating modes on high-speed modulation performance of strongly injection-locked unidirectional semiconductor microring lasers.

  18. Performance Optimization Design for a High-Speed Weak FBG Interrogation System Based on DFB Laser

    PubMed Central

    Yao, Yiqiang; Li, Zhengying; Wang, Yiming; Liu, Siqi; Dai, Yutang; Gong, Jianmin; Wang, Lixin

    2017-01-01

    A performance optimization design for a high-speed fiber Bragg grating (FBG) interrogation system based on a high-speed distributed feedback (DFB) swept laser is proposed. A time-division-multiplexing sensor network with identical weak FBGs is constituted to realize high-capacity sensing. In order to further improve the multiplexing capacity, a waveform repairing algorithm is designed to extend the dynamic demodulation range of FBG sensors. It is based on the fact that the spectrum of an FBG keeps stable over a long period of time. Compared with the pre-collected spectra, the distorted spectra waveform are identified and repaired. Experimental results show that all the identical weak FBGs are distinguished and demodulated at the speed of 100 kHz with a linearity of above 0.99, and the range of dynamic demodulation is extended by 40%. PMID:28640187

  19. Performance Optimization Design for a High-Speed Weak FBG Interrogation System Based on DFB Laser.

    PubMed

    Yao, Yiqiang; Li, Zhengying; Wang, Yiming; Liu, Siqi; Dai, Yutang; Gong, Jianmin; Wang, Lixin

    2017-06-22

    A performance optimization design for a high-speed fiber Bragg grating (FBG) interrogation system based on a high-speed distributed feedback (DFB) swept laser is proposed. A time-division-multiplexing sensor network with identical weak FBGs is constituted to realize high-capacity sensing. In order to further improve the multiplexing capacity, a waveform repairing algorithm is designed to extend the dynamic demodulation range of FBG sensors. It is based on the fact that the spectrum of an FBG keeps stable over a long period of time. Compared with the pre-collected spectra, the distorted spectra waveform are identified and repaired. Experimental results show that all the identical weak FBGs are distinguished and demodulated at the speed of 100 kHz with a linearity of above 0.99, and the range of dynamic demodulation is extended by 40%.

  20. Profile characteristics of excimer laser micromachined features

    NASA Astrophysics Data System (ADS)

    Tabat, Martin D.; O'Keeffe, Terence R.; Ho, Wen

    1993-04-01

    In our work with excimer lasers, we observe a complex depth profile in processed blind holes that is energy, material, and process independent. This feature occurs when processing ceramics, polyimide, semiconductors, and metals. Further it occurs under different optical configurations. An understanding of this phenomena is essential when micron-precision features are required. We present our findings and explore explanations.

  1. Investigations on high speed directly modulated microdisk lasers accounting for radial carrier hole burning

    NASA Astrophysics Data System (ADS)

    Huang, Yong-Zhen; Lv, Xiao-Meng; Zou, Ling-Xiu; Long, Heng; Xiao, Jin-Long; Yang, Yue-De; Du, Yun

    2014-04-01

    High-speed modulation characteristics are investigated for microdisk lasers theoretically and experimentally. In rate equation analysis, the microdisk resonator is radially divided into two regions under uniform carrier density approximation in each region. The injection current profile, carrier spatial hole burning, and diffusion are accounted for in the evaluation of small-signal modulation curves and the simulation of large-signal responses. The numerical results indicate that a wide mode field pattern in radial direction has merit for high-speed modulation, which is expected for coupled modes in the microdisk lasers connected with an output waveguide. For a 15-μm-radius microdisk laser connected with a 2-μm-wide output waveguide, the measured small-signal response curves with a low-frequency roll-off are well in agreement with the simulated result at a 2-μm radial width for the mode intensity distribution. The resonant frequencies of 7.2, 5.9, and 3.9 GHz are obtained at the temperatures of 287, 298, and 312 K from the small-signal response curves, and clear eye diagrams at 12.5 Gb/s with an extinction ratio of 6.1 dB are observed for the microdisk laser at the biasing current of 38 mA and 287 K.

  2. Combustion Effects in Laser-oxygen Cutting: Basic Assumptions, Numerical Simulation and High Speed Visualization

    NASA Astrophysics Data System (ADS)

    Zaitsev, Alexander V.; Ermolaev, Grigory V.

    Laser-oxygen cutting is very complicated for theoretical description technological process. Iron-oxygen combustion playing a leading role making it highly effective, able to cut thicker plates and, at the same time, producing special types of striations and other defects on the cut surface. In this paper results of numerical simulation based on elementary assumptions on iron-oxygen combustion are verified with high speed visualization of laser-oxygen cutting process. On a base of assumption that iron oxide lost its protective properties after melting simulation of striation formation due cycles of laser induced non self-sustained combustion is proposed. Assumption that reaction limiting factor is oxygen transport from the jet to cutting front allows to calculate reaction intensity by solving Navier - Stokes and diffusion system in gas phase. Influence of oxygen purity and pressure is studied theoretically. The results of numerical simulation are examined with high speed visualization of laser-oxygen cutting of 4-20 mm mild steel plates at cutting conditions close to industrial.

  3. High-speed quantitative phase imaging of dynamic thermal deformation in laser irradiated films

    NASA Astrophysics Data System (ADS)

    Taylor, Lucas N.; Brown, Andrew K.; Olson, Kyle D.; Talghader, Joseph J.

    2015-11-01

    We present a technique for high-speed imaging of the dynamic thermal deformation of transparent substrates under high-power laser irradiation. Traditional thermal sensor arrays are not fast enough to capture thermal decay events. Our system adapts a Mach-Zender interferometer, along with a high-speed camera to capture phase images on sub-millisecond time-scales. These phase images are related to temperature by thermal expansion effects and by the change of refractive index with temperature. High power continuous-wave and long-pulse laser damage often hinges on thermal phenomena rather than the field-induced effects of ultra-short pulse lasers. Our system was able to measure such phenomena. We were able to record 2D videos of 1 ms thermal deformation waves, with 6 frames per wave, from a 100 ns, 10 mJ Q-switched Nd:YAG laser incident on a yttria-coated glass slide. We recorded thermal deformation waves with peak temperatures on the order of 100 degrees Celsius during non-destructive testing.

  4. In vivo measurements of thermal load during ablation in high-speed laser corneal refractive surgery.

    PubMed

    de Ortueta, Diego; Magnago, Thomas; Triefenbach, Nico; Arba Mosquera, Samuel; Sauer, Udo; Brunsmann, Ulrich

    2012-01-01

    To evaluate the thermal load of ablation in high-speed laser corneal refractive surgery with the AMARIS excimer laser (SCHWIND eye-tech-solutions). Thermal load from refractive corrections on human corneas using a 500-Hz laser system with a fluence of 500 mJ/cm(2) and aspheric ablation profiles was recorded with an infrared thermography camera. Each single in vivo measurement was analyzed and temperature values were evaluated. Overall, the maximum temperature change of the ocular surface induced by the refractive ablations was ≤4°C. The increase in the peak temperature of the ocular surface never exceeded 35°C in any case. This low thermal load was independent of the amount of correction the eye achieved. The thermal load of the ablation in high-speed laser corneal refractive surgery was minimized using a computer algorithm to control the peak temperature to avoid corneal collagen denaturation with minimal compromise on treatment duration. Copyright 2012, SLACK Incorporated.

  5. Intrusive effects of repetitive laser pulsing in high-speed tracer-LIF measurements

    NASA Astrophysics Data System (ADS)

    Papageorge, M.; Sutton, J. A.

    2017-05-01

    The effects of repetitive laser pulsing on laser-induced fluorescence (LIF) signals from three popular organic flow tracers, acetone, 3-pentanone, and biacetyl are examined experimentally in the context of high-speed PLIF imaging. The effects of varying the incident laser fluence, laser repetition rates, tracer mole fractions, and carrier gas (air or N2) are investigated. Repetitive laser pulsing leads to changes in the measured LIF signal as a function of laser pulse number for all three tracers. For biacetyl/air mixtures, the LIF signal increases as a function of pulse number and the LIF signal increase per pulse is observed to be a function of the incident laser fluence. For biacetyl/air mixtures at room temperature, the increase in LIF signal during repetitive laser pulsing is attributed solely to absorptive heating of the probe volume, which is confirmed by Rayleigh scattering thermometry measurements. For acetone and 3-pentanone mixtures in the air, the LIF signal decreases with increasing pulse number and the LIF signal depletion per pulse is a linear function of incident laser fluence. This allows the signal depletion per pulse from acetone and 3-pentanone to be normalized by laser fluence and generalized to a single parameter of 0.002%/pulse/(mJ/cm2). There is no discernable effect of varying the tracer mole fraction or the laser repetition rate over the range of values investigated. The substitution of N2 for the air as a carrier gas leads to a significant decrease in the signal depletion per pulse. The potential mechanisms for the enhanced signal depletion in the presence of oxygen are discussed. A likely source is "photo-oxidation", where the products of laser photolysis react with the surrounding O2 to form the highly reactive hydroxyl (OH) radical, which then oxidizes the tracer. Overall, the current results indicate that under repetitive laser pulsing conditions (i.e., high-speed imaging), the tracer-LIF measurement techniques can be considered

  6. 4 Gbps direct modulation of 450 nm GaN laser for high-speed visible light communication.

    PubMed

    Lee, Changmin; Zhang, Chong; Cantore, Michael; Farrell, Robert M; Oh, Sang Ho; Margalith, Tal; Speck, James S; Nakamura, Shuji; Bowers, John E; DenBaars, Steven P

    2015-06-15

    We demonstrate high-speed data transmission with a commercial high power GaN laser diode at 450 nm. 2.6 GHz bandwidth was achieved at an injection current of 500 mA using a high-speed visible light communication setup. Record high 4 Gbps free-space data transmission rate was achieved at room temperature.

  7. High-speed modelocked semiconductor lasers and applications in coherent photonic systems

    NASA Astrophysics Data System (ADS)

    Lee, Wangkuen

    1.55-mum high-speed modelocked semiconductor lasers are theoretically and experimentally studied for various coherent photonic system applications. The modelocked semiconductor lasers (MSLs) are designed with high-speed (>5 GHz) external cavity configurations utilizing monolithic two-section curved semiconductor optical amplifiers. By exploiting the saturable absorber section of the monolithic device, passive or hybrid mode-locking techniques are used to generate short optical pulses with broadband optical frequency combs. Laser frequency stability is improved by applying the Pound-Drever-Hall (PDH) frequency stabilization technique to the MSLs. The improved laser performance after the frequency stabilization (a frequency drifting of less than 350 MHz), is extensively studied with respect to the laser linewidth (˜ 3 MHz), the relative intensity noise (RIN) (< -150 dB/Hz), as well as the modal RIN (˜ 3 dB reduction). MSL to MSL, and tunable laser to MSL synchronization is demonstrated by using a dual-mode injection technique and a modulation sideband injection technique, respectively. Dynamic locking behavior and locking bandwidth are experimentally and theoretically studied. Stable laser synchronization between two MSLs is demonstrated with an injection seed power on the order of a few microwatt. Several coherent heterodyne detections based on the synchronized MSL systems are demonstrated for applications in microwave photonic links and ultra-dense wavelength division multiplexing (UD-WDM) system. In addition, efficient coherent homodyne balanced receivers based on synchronized MSLs are developed and demonstrated for a spectrally phase-encoded optical CDMA (SPE-OCDMA) system.

  8. Femtosecond laser micromachining of aluminum surfaces under controlled gas atmospheres

    NASA Astrophysics Data System (ADS)

    Robinson, G. M.; Jackson, M. J.

    2006-04-01

    The interaction of 180 femtosecond (fs), 775 nm laser pulses with the surface of aluminum under controlled gas atmospheres at ambient pressure has been investigated to study material redeposition, residual surface roughness, and ablation rate. The effect of using various gases to protect the surface of the material appears to interfere with the effects of the plasma and can change the resulting microstructure of the machined surface. By varying the combinations of fluence and laser-scanning speed during ultrafast ablation at high repetition rates, an optimum micromachining condition can be reached, depending on the type of gas used during machining. The debris produced under certain laser-machining conditions tends to produce pure aluminum nanoparticles that are deposited very close to the machined feature by the gas used to protect the surface of the aluminum.

  9. Quasi-continuous burst-mode laser for high-speed planar imaging.

    PubMed

    Slipchenko, Mikhail N; Miller, Joseph D; Roy, Sukesh; Gord, James R; Danczyk, Stephen A; Meyer, Terrence R

    2012-04-15

    The pulse-burst duration of a compact burst-mode Nd:YAG laser is extended by one order of magnitude compared to previous flashlamp-pumped designs by incorporating a fiber oscillator and diode-pumped solid-state amplifiers. The laser has a linewidth of <2 GHz at 1064.3 nm with 150 mJ per individual pulse at 10 kHz. The performance of the system is evaluated by using the third-harmonic output at 354.8 nm for high-speed planar laser-induced fluorescence of formaldehyde in a lifted methane-air diffusion flame. A total of 100 and 200 sequential images of unsteady fluid-flame interactions are acquired at repetition rates of 10 kHz and 20 kHz, respectively.

  10. PULPAL TEMPERATURE INCREASE WITH HIGH-SPEED HANDPIECE, ER:YAG LASER AND ULTRASOUND TIPS

    PubMed Central

    Mollica, Fernanda Brandão; Camargo, Fernanda Pelogia; Zamboni, Sandra Costa; Pereira, Sarina Maciel Braga; Teixeira, Symone Cristina; Nogueira, Lafayette

    2008-01-01

    The aim of this study was to compare intrapulpal temperature increase produced by high-speed handpiece, Er:YAG laser and CVDentus ultrasound tips during cavity preparation. Thirty bovine mandibular incisors with an enamel/dentin thickness of 4 mm at buccal surface had their roots amputated and were allocated to the following groups (n=10): Group I- high-speed handpiece; Group II- noncontact Er:YAG laser (250 mJ/4Hz); and Group III- CVDentus ultrasouns tips. All devices were used with water cooling. Class V cavities were prepared to a depth of 3.5 mm, measured with a periodontal probe. A type T thermocouple was placed inside the pulp chamber to determine the temperature increase (°C), which was recorded by a data acquisition system ADS 2000 IP (Lynx Technology) linked to a notebook computer. Data were analyzed statistically by oneway ANOVA and Tukey's test (p=0.05). The mean temperature rises were: 1.10°C (±0.56) for Group I, 0.84°C (±0.55) for Group II, and 3.00°C (± 1.34) for Group III. There were no statistically significant differences (p>0.05) between Groups I and II, but both of them differed significantly from Group III (p<0.05). In conclusion, the use of Er:YAG laser and high-speed handpiece for cavity preparation resulted in similar temperature increase. Although ultrasound tips generated significantly higher intrapulpal temperature increase, it remained below the critical value of 5.5°C and may be considered safe for use. PMID:19089220

  11. Pulpal temperature increase with high-speed handpiece, Er:YAG laser and ultrasound tips.

    PubMed

    Mollica, Fernanda Brandão; Camargo, Fernanda Pelogia; Zamboni, Sandra Costa; Pereira, Sarina Maciel Braga; Teixeira, Symone Cristina; Nogueira, Lafayette

    2008-01-01

    The aim of this study was to compare intrapulpal temperature increase produced by high-speed handpiece, Er:YAG laser and CVDentus ultrasound tips during cavity preparation. Thirty bovine mandibular incisors with an enamel/dentin thickness of 4 mm at buccal surface had their roots amputated and were allocated to the following groups (n=10): Group I- high-speed handpiece; Group II- noncontact Er:YAG laser (250 mJ/4 Hz); and Group III- CVDentus ultrasouns tips. All devices were used with water cooling. Class V cavities were prepared to a depth of 3.5 mm, measured with a periodontal probe. A type T thermocouple was placed inside the pulp chamber to determine the temperature increase (degrees C), which was recorded by a data acquisition system ADS 2000 IP (Lynx Technology) linked to a notebook computer. Data were analyzed statistically by one-way ANOVA and Tukey's test (p=0.05). The mean temperature rises were: 1.10 degrees C (+/-0.56) for Group I, 0.84 degrees C (+/-0.55) for Group II, and 3.00 degrees C (+/- 1.34) for Group III. There were no statistically significant differences (p>0.05) between Groups I and II, but both of them differed significantly from Group III (p<0.05). In conclusion, the use of Er:YAG laser and high-speed handpiece for cavity preparation resulted in similar temperature increase. Although ultrasound tips generated significantly higher intrapulpal temperature increase, it remained below the critical value of 5.5 degrees C and may be considered safe for use.

  12. Full-field high-speed laser Doppler imaging system for blood-flow measurements

    NASA Astrophysics Data System (ADS)

    Serov, Alexandre; Lasser, Theo

    2006-02-01

    We describe the design and performance of a new full-field high-speed laser Doppler imaging system developed for mapping and monitoring of blood flow in biological tissue. The total imaging time for 256x256 pixels region of interest is 1.2 seconds. An integrating CMOS image sensor is utilized to detect Doppler signal in a plurality of points simultaneously on the sample illuminated by a divergent laser beam of a uniform intensity profile. The integrating property of the detector improves the signal-to-noise ratio of the measurement, which results in high-quality flow-images provided by the system. The new technique is real-time, non-invasive and the instrument is easy to use. The wide range of applications is one of the major challenges for a future application of the imager. High-resolution high-speed laser Doppler perfusion imaging is a promising optical technique for diagnostic and assessing the treatment effect of the diseases such as e.g. atherosclerosis, psoriasis, diabetes, skin cancer, allergies, peripheral vascular diseases, skin irritancy and wound healing. We present some biological applications of the new imager and discuss the perspectives for the future implementations of the imager for clinical and physiological applications.

  13. Cubic Structure and Cation Disordering in Ybco Thin Film Deposited by High Speed Pulsed Laser Deposition

    NASA Astrophysics Data System (ADS)

    Suh, Jeong-Dae; Sung, Gun Yong; Kang, Kwang Yong

    We have investigated the crystalline structure of high rate deposited YBa2Cu3Ox thin films prepared by high speed pulsed laser deposition. A cation disordered cubic structure with lattice parameter of 0.39 nm was found in YBCO thin film deposited at 12.2 nm/s deposition rate and 650°C substrate temperature conditions. The short range ordered cubic YBa2Cu3Ox thin film growth at high deposition rate was explained by the short migration length of Y and Ba cation atoms owing to the high incident flux rate.

  14. Technological Aspects of High Speed Direct Laser Deposition Based on Heterophase Powder Metallurgy

    NASA Astrophysics Data System (ADS)

    Turichin, G. A.; Klimova, O. G.; Zemlyakov, E. V.; Babkin, K. D.; Kolodyazhnyy, D. Yu.; Shamray, F. A.; Travyanov, A. Ya.; Petrovskiy, P. V.

    The article deals with physical peculiarities and technology of high speed processes of direct laser deposition. On the base of theoretic research and computer modeling the powder transfer has been optimized, increasing process stability and productivity. Principles of nozzles design also have been developed in accordance with technological needs. An influence of process mode on product properties and material structure was defined for heat resisted Ni-based superalloys. Developed technology provided the mechanic properties of products on the level of rolled material and allows avoid heat treatment and HIP in production process. Possible ways for increasing process performance and economic efficiency also have been discussed.

  15. High Speed 1.55 μm Lasers for Fiber Optic Transmission

    NASA Astrophysics Data System (ADS)

    Morton, Paul A.

    This paper describes the essential elements for creating a practical wide bandwidth directly modulated laser source. This includes considerations of the intrinsic limitations of the laser structure, due to the resonant frequency and damping of the laser output, together with carrier transport issues to allow carriers in the device active region to be efficiently modulated at high speeds. The use of a P-doped compressively strained multiple-quantum well active region to provide high intrinsic speed and remove transport limitations is described, together with record setting results of 25 GHz modulation bandwidth for a 1.55 μm Fabry-Perot laser and 26 GHz bandwidth for a 1.55 μm DFB laser. The challenges of providing high bandwidth electrical connections to the laser on a suitable submount, together with fiber attachment and microwave packaging are discussed. Results of fully packaged 1.55 μm DFB lasers with 25 GHz modulation bandwidth are shown. Digital modulation of the packaged 1.55 μm DFB including impedance matching is described, and the transient wavelength chirp is presented. This low chirp is reduced further using an optical filter, to provide a 10 GBit/s source that can transmit error free over 38.5 km of standard optical fiber.

  16. Superamphiphobic miniature boat fabricated by laser micromachining

    NASA Astrophysics Data System (ADS)

    Yin, Kai; Dong, Xinran; Zhang, Fan; Wang, Cong; Duan, Ji'an

    2017-03-01

    We fabricated a superamphiphobic miniature boat with marked drag reduction and excellent loading capacity using femtosecond laser direct writing technology. The as-prepared superamphiphobic surface of the boat exhibited apparent contact angles larger than 150° toward both water and oil. Miniature boats with the superamphiphobic surface slid effortlessly on both water and oil-polluted water surfaces, with an increase in sliding distance by up to 52% and load increase of up to 27% compared with those of a boat with an untreated surface. A potential mechanism that explains the excellent performance of the superamphiphobic miniature boat was also discussed. This work provides a simple and economically viable strategy to obtain advanced surfaces for use in microfluidics and marine engineering.

  17. Laser micromachining of biofactory-on-a-chip devices

    NASA Astrophysics Data System (ADS)

    Burt, Julian P.; Goater, Andrew D.; Hayden, Christopher J.; Tame, John A.

    2002-06-01

    Excimer laser micromachining provides a flexible means for the manufacture and rapid prototyping of miniaturized systems such as Biofactory-on-a-Chip devices. Biofactories are miniaturized diagnostic devices capable of characterizing, manipulating, separating and sorting suspension of particles such as biological cells. Such systems operate by exploiting the electrical properties of microparticles and controlling particle movement in AC non- uniform stationary and moving electric fields. Applications of Biofactory devices are diverse and include, among others, the healthcare, pharmaceutical, chemical processing, environmental monitoring and food diagnostic markets. To achieve such characterization and separation, Biofactory devices employ laboratory-on-a-chip type components such as complex multilayer microelectrode arrays, microfluidic channels, manifold systems and on-chip detection systems. Here we discuss the manufacturing requirements of Biofactory devices and describe the use of different excimer laser micromachined methods both in stand-alone processes and also in conjunction with conventional fabrication processes such as photolithography and thermal molding. Particular attention is given to the production of large area multilayer microelectrode arrays and the manufacture of complex cross-section microfluidic channel systems for use in simple distribution and device interfacing.

  18. Studying the mechanism of micromachining by short pulsed laser

    NASA Astrophysics Data System (ADS)

    Gadag, Shiva

    The semiconductor materials like Si and the transparent dielectric materials like glass and quartz are extensively used in optoelectronics, microelectronics, and microelectromechanical systems (MEMS) industries. The combination of these materials often go hand in hand for applications in MEMS such as in chips for pressure sensors, charge coupled devices (CCD), and photovoltaic (PV) cells for solar energy generation. The transparent negative terminal of the solar cell is made of glass on one surface of the PV cell. The positive terminal (cathode) on the other surface of the solar cell is made of silicon with a glass negative terminal (anode). The digital watches and cell phones, LEDs, micro-lens, optical components, and laser optics are other examples for the application of silicon and or glass. The Si and quartz are materials extensively used in CCD and LED for digital cameras and CD players respectively. Hence, three materials: (1) a semiconductor silicon and transparent dielectrics,- (2) glass, and (3) quartz are chosen for laser micromachining as they have wide spread applications in microelectronics industry. The Q-switched, nanosecond pulsed lasers are most extensively used for micro-machining. The nanosecond type of short pulsed laser is less expensive for the end users than the second type, pico or femto, ultra-short pulsed lasers. The majority of the research work done on these materials (Si, SiO 2, and glass) is based on the ultra-short pulsed lasers. This is because of the cut quality, pin point precision of the drilled holes, formation of the nanometer size microstructures and fine features, and minimally invasive heat affected zone. However, there are many applications such as large surface area dicing, cutting, surface cleaning of Si wafers by ablation, and drilling of relatively large-sized holes where some associated heat affected zone due to melting can be tolerated. In such applications the nanosecond pulsed laser ablation of materials is very

  19. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Laser—ultrasonic formation of melts of high-speed tool steels

    NASA Astrophysics Data System (ADS)

    Gureev, D. M.

    1994-09-01

    A study was made of the influence of ultrasonic vibrations on the processes of heat and mass transfer, and of structure formation during ultrafast crystallisation of laser melts of T1 high-speed tool steel. Acoustic flows which appeared in laser melts effectively smoothed out the temperature inhomogeneities and flattened the relief of the molten surface even when the laser radiation acted for just ~1 ms. The transformation of the mechanical energy of ultrasonic vibrations into heat increased the depth of the laser melt baths and suppressed crack formation. The observed changes in the structural and phase composition appeared as a change in the microhardness of the solidified laser melts. The geometry of coupling of ultrasound into a laser melt influenced the changes in the microhardness, suggesting a need for a more detailed analysis of the structure formation processes in the course of ultrafast crystallisation of laser melts in an ultrasonic field.

  20. High speed photoacoustic tomography system with low cost portable pulsed diode laser

    NASA Astrophysics Data System (ADS)

    Upputuri, Paul Kumar; Sivasubramanian, Kathyayini; Pramanik, Manojit

    2015-07-01

    Photoacoustic tomography (PAT) is a potential hybrid imaging modality that has attracted great attention in the fields of medical imaging. In order to generate photoacoustic signal efficiently Q-switched Nd:YAG pump lasers capable of generating tens of millijoules of nanosecond laser pulses have been widely used. However, PAT systems using such lasers have limitations in clinical applications because of their high cost, large size, and cooling requirements. Furthermore, the low pulse repetition rate (PRR) of tens of hertz is not suitable for real-time PAT. So, there is a need for inexpensive, compact, simple, fast imaging system for clinical applications. Nanosecond pulsed laser diodes could meet these requirements. In this work, we present a high-speed photoacoustic tomography imaging system that uses a compact and yet relatively powerful near-infrared pulsed laser diode. The PAT system was tested on phantoms to verify its potential imaging speed. Photoacoustic reconstructed images at different scanning speeds are presented. With single ultrasound detector scanning, the system could provide PA image ~10 times faster than the Nd:YAG laser based systems.

  1. Laser direct imaging of transparent indium tin oxide electrodes using high speed stitching techniques

    NASA Astrophysics Data System (ADS)

    Cheng, Pi-Ying; Hsiao, Wen-Tse; Chung, Chien-Kai; Tseng, Shih-Feng; Liao, Ien-Chang

    2014-09-01

    To accomplish an electrode patterning in large area, we present a high speed stitching technique used in an ultraviolet laser processing system and investigate the interaction between laser beams and indium tin oxide (ITO) thin films deposited on glass substrates. After optimizing the process parameters of the laser direct imaging (LDI) for the large-area electrode patterning, the ablated lines looked like regularly fish-scale marks of about a 40 μm diameter and a 120 nm depth around the processing path. The parameters includes the laser power of 1W, the scanning speed of galvanometers of 800 mm/s, and the laser pulse repetition frequency of 50 kHz. Moreover, the resistance value of the ablated ITO thin film is larger than 200MΩ that is electrically insulated from the other regions of electrode structure. LDI technology with UV laser beam has great potential applications in patterning on wafer or sapphire substrates and patterning a conductive layer deposited on the touch panels for semiconductor and optoelectric industries, respectively.

  2. Applications of copper vapor laser lighting in high-speed motion analysis

    NASA Astrophysics Data System (ADS)

    Hogan, Daniel C.

    1991-01-01

    Over the past few years copper vapor lasers have become an important tool in high speed photography as a high-tech strobe lighting source. The short flash duration ( 025 microseconds) high brightness (of the order of 20 million Lumens) and high flash rates (32 per second from a single laser 96 per second from three lasers) of copper vapor lasers have enabled high resolution analysis of processes that previously could not be explored using conventional incandescent continuous or strobe lighting sources. A summary of applications that have benefited from the use of copper laser lighting will be presented. These applications include: analysis of shock waves in turbine engine blades analysis of spinning fibers in the textile industry analysis of the bursting of high pressure storage vessels analysis of turbulent flow in internal combustion engines and capture of ballistic data of objects travelling in excess of 1500ms1(3 mph). Discussion of why copper laser lighting was crucial in each of these applications will be presented.

  3. High-speed Optical Coherence Tomography for Management after Laser in Situ Keratomileusis

    PubMed Central

    Avila, Mariana; Li, Yan; Song, Jonathan C.; Huang, David

    2007-01-01

    PURPOSE: To report applications of optical coherence tomography (OCT) in the management of laser in situ keratomileusis (LASIK) related problems. SETTING: Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA. METHODS: Five patients referred for LASIK-related problems were enrolled in a prospective observational study. Clinical examination, ultrasound (US) pachymetry, Placido ring slit-scanning corneal topography (Orbscan II, Bausch & Lomb), and high-speed corneal OCT were performed. RESULTS: In cases of regression and keratectasia, OCT provided thickness measurements of the cornea, flap, and posterior stromal bed. Locations of tissue loss and flap interface planes were identified in a case with a recut enhancement complication. The information was used to determine whether further laser ablation was safe, confirm keratectasia, and manage complications. Optical coherence tomography measurements of central corneal thickness agreed well with US pachymetry measurements (difference 6.4 mm G 11.7 [SD]) (P Z .026), while Orbscan significantly underestimated corneal thickness (-67.5 ± 72.5 μm) (P = .17). CONCLUSIONS: High-speed OCT provided noncontact imaging and measurement of LASIK anatomy. It was useful in monitoring LASIK results and evaluating complications. PMID:17081866

  4. High-speed, image-based eye tracking with a scanning laser ophthalmoscope

    PubMed Central

    Sheehy, Christy K.; Yang, Qiang; Arathorn, David W.; Tiruveedhula, Pavan; de Boer, Johannes F.; Roorda, Austin

    2012-01-01

    We demonstrate a high-speed, image-based tracking scanning laser ophthalmoscope (TSLO) that can provide high fidelity structural images, real-time eye tracking and targeted stimulus delivery. The system was designed for diffraction-limited performance over an 8° field of view (FOV) and operates with a flexible field of view of 1°–5.5°. Stabilized videos of the retina were generated showing an amplitude of motion after stabilization of 0.2 arcmin or less across all frequencies. In addition, the imaging laser can be modulated to place a stimulus on a targeted retinal location. We show a stimulus placement accuracy with a standard deviation less than 1 arcmin. With a smaller field size of 2°, individual cone photoreceptors were clearly visible at eccentricities outside of the fovea. PMID:23082300

  5. Freeze frame analysis on high speed cinematography of Nd/YAG laser explosions in ocular tissues.

    PubMed

    Vernon, S A; Cheng, H

    1986-05-01

    High speed colour cinematography at 400 frames per second was used to photograph both single and train burst Nd/YAG laser applications in ox eyes at threshold energy levels. Measurements of the extent and speed of particle scatter and tissue distortion from the acoustic transient were made from a sequential freeze frame analysis of the films. Particles were observed to travel over 8 mm from the site of Nd/YAG application 20 milliseconds after a single pulse at initial speeds in excess of 20 km/h. The use of train bursts of pulses was seen to increase the number of particles scattered and project the wavefront of particles further from the point of laser application.

  6. Travelling wave analysis on high-speed performance of Q-modulated distributed feedback laser.

    PubMed

    Zhi, Jiankun; Zhu, Hongli; Liu, Dekun; Wang, Lei; He, Jian-Jun

    2012-01-30

    The structure of a Q-modulated distributed feedback laser is designed and simulated. A large reflectivity modulation of the rear reflector is achieved by using an anti-resonant cavity formed by two deep trenches with the one between the modulator and phase section filled by a high index dielectric material. The travelling wave model is presented to analyze the high speed performance of the laser. Due to the effect of the wave propagation in the structure, the modulation extinction ratio decreases with increasing cavity length. It is shown that 40 Gb/s RZ signal modulation can be achieved with an extinction ratio of 7 dB and 10 dB, respectively, for a cavity length of 500 μm and 300 μm.

  7. High-speed high-resolution heterodyne interferometer using a laser with low beat frequency.

    PubMed

    Diao, Xiaofei; Hu, Pengcheng; Xue, Zi; Kang, Yanhui

    2016-01-01

    A high-speed high-resolution heterodyne interferometer using a laser with low beat frequency is developed. The interferometer has two spatially separated parallel beams with different frequencies. Two interference signals with opposite Doppler shift are optically generated by the interferometric optics. The measurement electronics uses two identical phasemeters for the two opposite interference signals. The two interference signals are selectively used according to the speed of the target, which makes sure that the Doppler shift of the selected signal is always positive, so that the measurable speed is no longer limited by the beat frequency of the laser source. Experimental results show that the measurement resolution is 0.62 nm. The measurable speed can exceed the restriction determined by the beat frequency. Compared with a commercial interferometer, the displacement difference is less than 40 nm in a travel range of 900 mm.

  8. High-power high-speed single-mode diode lasers for optical intersatellite link applications

    NASA Astrophysics Data System (ADS)

    Li, Benjamin; Sha, WeiJian; Yeh, PingHui S.; Nagarajan, Radhakrishnan; Craig, Richard R.

    1998-05-01

    High power single-mode AlGaAs semiconductor lasers operating between 820 nm and 860 nm (SDL-5400 series diodes) have been successfully qualified for deployment in many free-space inter-satellite communication link programs. Traditionally these high power devices did not have sufficient bandwidth for direct high speed modulation because of large device and package parasitics. We have improved the device parasitics of the SDL-5430 laser diode, i.e. reduced the RC product, from 240 ps to about 40 ps. The initial measurements indicate that this device (SDL-5480) is suitable for high power optical inter-satellite link (OISL) applications at data rates greater than 1 Gbit/s. The preliminary life test indicates that the new device has better a reliability than the previous design.

  9. Beam shaping applications in laser micromachining for the microelectronics industry

    NASA Astrophysics Data System (ADS)

    Dunsky, Corey M.

    2001-10-01

    Laser micromachining has been a part of the manufacturing process for semiconductors and microelectronics devices for several decades. More recent applications such as the drilling of microvia holes in high-density electronic packages have recently entered broad industrial use for high-volume production. In such applications, process stability and throughput are key drivers of commercial success. Particularly in the UV, where solid-state laser power is growing rapidly but is still limited to less than 10 watts, innovations that permit the available laser power to be applied at the work surface more efficiently are of interest. Within the last two years, the use of beam shapers to create round laser spots with near-uniform irradiance at the work surface has been demonstrated. Shaping the irradiance profile has been shown to both increase process speed and improve the quality of the drilled holes, which range in diameter between 20 and 150 micrometers . This paper gives an historical overview of laser via drilling, presents the Gaussian-to-flattop beam shaping optics used in the microvia laser drills, and discusses the process results obtained.

  10. Method of high speed flow field influence and restrain on laser communication

    NASA Astrophysics Data System (ADS)

    Meng, Li-xin; Wang, Chun-hui; Qian, Cun-zhu; Wang, Shuo; Zhang, Li-zhong

    2013-08-01

    For laser communication performance which carried by airplane or airship, due to high-speed platform movement, the air has two influences in platform and laser communication terminal window. The first influence is that aerodynamic effect causes the deformation of the optical window; the second one is that a shock wave and boundary layer would be generated. For subsonic within the aircraft, the boundary layer is the main influence. The presence of a boundary layer could change the air density and the temperature of the optical window, which causes the light deflection and received beam spot flicker. Ultimately, the energy hunting of the beam spot which reaches receiving side increases, so that the error rate increases. In this paper, aerodynamic theory is used in analyzing the influence of the optical window deformation due to high speed air. Aero-optics theory is used to analyze the influence of the boundary layer in laser communication link. Based on this, we focused on working on exploring in aerodynamic and aero-optical effect suppression method in the perspective of the optical window design. Based on planning experimental aircraft types and equipment installation location, we optimized the design parameters of the shape and thickness of the optical window, the shape and size of air-management kit. Finally, deformation of the optical window and air flow distribution were simulated by fluid simulation software in the different mach and different altitude fly condition. The simulation results showed that the optical window can inhibit the aerodynamic influence after optimization. In addition, the boundary layer is smoothed; the turbulence influence is reduced, which meets the requirements of the airborne laser communication.

  11. Efficient femtosecond laser micromachining of bulk 3C-SiC

    NASA Astrophysics Data System (ADS)

    Farsari, M.; Filippidis, G.; Zoppel, S.; Reider, G. A.; Fotakis, C.

    2005-09-01

    We demonstrate surface micromachining of bulk 3C silicon carbide (3C-SiC) wafers by employing tightly focused infrared femtosecond laser pulses of energy less than 10 nJ directly from a femtosecond laser oscillator, thus eliminating the need for an amplified system and increasing the micromachining speed by more than four orders of magnitude. In addition, we show that high aspect ratio through-tapered vias can be drilled in 400 µm thick wafers using an amplified femtosecond laser.

  12. Single step high-speed printing of continuous silver lines by laser-induced forward transfer

    NASA Astrophysics Data System (ADS)

    Puerto, D.; Biver, E.; Alloncle, A.-P.; Delaporte, Ph.

    2016-06-01

    The development of high-speed ink printing process by Laser-Induced Forward Transfer (LIFT) is of great interest for the printing community. To address the problems and the limitations of this process that have been previously identified, we have performed an experimental study on laser micro-printing of silver nanoparticle inks by LIFT and demonstrated for the first time the printing of continuous conductive lines in a single pass at velocities of 17 m/s using a 1 MHz repetition rate laser. We investigated the printing process by means of a time-resolved imaging technique to visualize the ejection dynamics of single and adjacent jets. The control of the donor film properties is of prime importance to achieve single step printing of continuous lines at high velocities. We use a 30 ps pulse duration laser with a wavelength of 343 nm and a repetition rate from 0.2 to 1 MHz. A galvanometric mirror head controls the distance between two consecutives jets by scanning the focused beam along an ink-coated donor substrate at different velocities. Droplets and lines of silver inks are laser-printed on glass and PET flexible substrates and we characterized their morphological quality by atomic force microscope (AFM) and optical microscope.

  13. Laser-high-speed-DSC: Process-oriented Thermal Analysis of PA 12 in Selective Laser Sintering

    NASA Astrophysics Data System (ADS)

    Lanzl, Lydia; Wudy, Katrin; Drexler, Maximilian; Drummer, Dietmar

    In the Selective Laser Sintering process very high heating rates occur due to the melting of the material by a laser. Extreme scanning rates could not be measured by conventional thermal analysis methods, since typical heating rates for DSC (differential scanning calorimetry) are between 5-20K min-1. By using a Laser-High-Speed-DSC, a self-developed combination of a Flash-DSC and a fitted laser head, the sample is directly heated by a CO2 laser like in the SLS process. These experiments allow a process-oriented thermal analyzation of the material. In this paper, the set-up and function of this new measuring method is introduced. Furthermore, the reliability of the measurements is evaluated by statistical design of experiment methods. By using this new measuring method, the time-dependent melting behavior of the polymer can be analyzed. Moreover, sample temperatures and heating rates dependent on laser exposure times can be quantified.

  14. High speed visible light communication using blue GaN laser diodes

    NASA Astrophysics Data System (ADS)

    Watson, S.; Viola, S.; Giuliano, G.; Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Targowski, G.; Watson, M. A.; White, H.; Rowe, D.; Laycock, L.; Kelly, A. E.

    2016-10-01

    GaN-based laser diodes have been developed over the last 20 years making them desirable for many security and defence applications, in particular, free space laser communications. Unlike their LED counterparts, laser diodes are not limited by their carrier lifetime which makes them attractive for high speed communication, whether in free space, through fiber or underwater. Gigabit data transmission can be achieved in free space by modulating the visible light from the laser with a pseudo-random bit sequence (PRBS), with recent results approaching 5 Gbit/s error free data transmission. By exploiting the low-loss in the blue part of the spectrum through water, data transmission experiments have also been conducted to show rates of 2.5 Gbit/s underwater. Different water types have been tested to monitor the effect of scattering and to see how this affects the overall transmission rate and distance. This is of great interest for communication with unmanned underwater vehicles (UUV) as the current method using acoustics is much slower and vulnerable to interception. These types of laser diodes can typically reach 50-100 mW of power which increases the length at which the data can be transmitted. This distance could be further improved by making use of high power laser arrays. Highly uniform GaN substrates with low defectivity allow individually addressable laser bars to be fabricated. This could ultimately increase optical power levels to 4 W for a 20-emitter array. Overall, the development of GaN laser diodes will play an important part in free space optical communications and will be vital in the advancement of security and defence applications.

  15. High-speed photodamage cell selection using a frequency-doubled argon ion laser.

    PubMed

    Keij, J F; Groenewegen, A C; Dubelaar, G B; Visser, J W

    1995-03-01

    A flow cytometer was developed for the high-speed "sorting" of desired cells by selectively irradiating (zapping) the undesired cells from a population. After previous efforts to photoinactivate cells with photosensitizers had failed, it was decided to exploit the photosensitivity of the cell's DNA at 257 nm. It was shown that a 257 nm laser output power of 20-100 mW was sufficient to induce a 4.5 log cell kill after the cells were processed through a focused 257 nm laser beam. Experiments proved that the photodamage flow cytometer (ZAPPER) could selectively photoinactivate cells at rates over 22,000 events/s, and selection purities ranged from 81% to 100%. The yields of the desired cells depended on the selection mode. In the Enrichment mode, the zap laser was not aimed at the jet, and only undesired cells were exposed to a brief ultraviolet (UV) pulse after modulation of the UV laser beam. The yields of desired cells ranged from 95% to 105%. In the Purge mode, the zap laser beam was aimed onto the jet, and only desired cells were allowed to pass after deflection of the UV laser beam; the yields of desired cells ranged from 12% to 52%. The cause of the reduced yields in the PURGE mode was traced to the fact that the Electro-Optic Modulator was used to modulate the zap laser proved too slow for the intended application. The lifetime of the frequency-doubling crystal used for the generation of the 257 nm beam was found to be limited to several days.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. High-speed fiber laser cutting of thick stainless steel for dismantling tasks

    NASA Astrophysics Data System (ADS)

    Shin, Jae Sung; Oh, Seong Yong; Park, Hyunmin; Chung, Chin-Man; Seon, Sangwoo; Kim, Taek-Soo; Lee, Lim; Choi, Byung-Seon; Moon, Jei-Kwon

    2017-09-01

    A high-speed fiber laser cutting technology of thick steels for dismantling tasks was achieved using a 6-kW fiber laser system. At first, a new cutting head for efficient cutting of thick steels was developed, which was composed by a collimator with a focal length of 160 mm and mirror-type focusing objects with a long focal length of 600 mm. The long focal length of the focusing object made it possible for the beam size to be small through the thick cutting material and the cutting efficiency was expected to increase compared with the short focal length. In addition, folding the beam facilitated the compact cutting head with a size of 160 mm (width) × 80 mm (height) × 640 mm (length) and a weight of 6.9 kg. In the cutting experiment, the laser beam was delivered to the cutting head by a 25-m long process fiber with a core diameter of 100 μm. The cutting performances were studied against the thicknesses of stainless steel plates. A maximum cutting speed of 72 mm/min was obtained for the 60-mm thick stainless steel plate cutting and the cut specimen showed an excellent kerf shape and a narrow kerf width. To the best of our knowledge, this cutting speed was higher than other previously reported results when cutting with a 6-kW laser power.

  17. High-speed imaging and evolution dynamics of laser induced deposition of conductive inks (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Makrygianni, Marina; Papazoglou, Symeon; Zacharatos, Filimonas; Chatzandroulis, Stavros; Zergioti, Ioanna

    2017-02-01

    During the last decade there is an ever-increasing interest for the study of laser processes dynamics and specifically of the Laser Induced Forward Transfer (LIFT) technique, since the evolution of the phenomena under investigation may provide real time metrology in terms of jet velocity, adjacent jet interaction and impact pressure. The study of such effects leads to a more thorough understanding of the deposition process, hence to an improved printing outcome and in these frames, this work presents a study on the dynamics of LIFT for conductive nanoparticles inks using high-speed imaging approaches. Moreover, in this study, we investigated the printing regimes and the printing quality during the transfer of copper (Cu) nanoink, which is a metallic nanoink usually employed in interconnect formation as well as the printing of silver nanowires, which provide transparency and may be used in applications where transparent electrodes are needed as in photovoltaics, batteries, etc. Furthermore, we demonstrate the fabrication of an all laser printed resistive chemical sensor device that combines Ag nanoparticles ink and graphene oxide, for the detection of humidity fabricated on a flexible polyimide substrate. The sensor device architecture was able to host multiple pairs of electrodes, where Ag nanoink or nanopaste were laser printed, to form the electrodes as well as the electrical interconnections between the operating device and the printed circuit board. Performance evaluation was conducted upon flow of different concentrations of humidity vapors to the sensor, and good response (500 ppm limit of detection) with reproducible operation was observed.

  18. High-speed femtosecond laser beam shaping based on binary holography using a digital micromirror device.

    PubMed

    Cheng, Jiyi; Gu, Chenglin; Zhang, Dapeng; Chen, Shih-Chi

    2015-11-01

    In this Letter, we present a digital micromirror device (DMD)-based ultrafast beam shaper, i.e., DUBS. To our knowledge, the DUBS is the first binary laser beam shaper that can generate high-resolution (1140×912 pixels) arbitrary beam modes for femtosecond lasers at a rate of 4.2 kHz; the resolution and pattern rate are limited by the DMD. In the DUBS, the spectrum of the input pulsed laser is first angularly dispersed by a transmission grating and subsequently imaged to a DMD with beam modulation patterns; the transmission grating and a high-reflectivity mirror together compensate the angular dispersion introduced by the DMD. The mode of the output beam is monitored by a CCD camera. In the experiments, the DUBS is programmed to generate four different beam modes, including an Airy beam, Bessel beam, Laguerre-Gaussian (LG) beam, and a custom-designed "peace-dove" beam via the principle of binary holography. To verify the high shaping rate, the Airy beam and LG beam are generated alternately at 4.2 kHz, i.e., the maximum pattern rate of our DMD. The overall efficiency of the DUBS is measured to be 4.7%. With the high-speed and high-resolution beam-shaping capability, the DUBS may find important applications in nonlinear microscopy, optical manipulation, and microscale/nanoscale laser machining, etc.

  19. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Investigation of laser plasma expansion in an ambient gas by high-speed photography

    NASA Astrophysics Data System (ADS)

    Anan'in, O. B.; Bykovskiĭ, Yu A.; Eremin, Yu V.; Stupitskiĭ, E. L.; Novikov, I. K.; Frolov, S. P.

    1991-07-01

    A method was developed for investigating the behavior of a laser plasma in vacuum and in an ambient gas by high-speed photography. Photographs were obtained of laser plasma expansion in an ambient gas at various pressures. A hydrodynamic instability of the laser plasma front was observed during expansion in an ambient gas. The experimental results were analyzed theoretically.

  20. Solid polymer electrolyte composite membrane comprising laser micromachined porous support

    DOEpatents

    Liu, Han [Waltham, MA; LaConti, Anthony B [Lynnfield, MA; Mittelsteadt, Cortney K [Natick, MA; McCallum, Thomas J [Ashland, MA

    2011-01-11

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 5 microns, are made by laser micromachining and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  1. Basic study on vibrations during tooth preparations caused by high-speed drilling and Er:YAG laser irradiation.

    PubMed

    Takamori, Kazunori; Furukawa, Hirohiko; Morikawa, Yoshikatsu; Katayama, Tadashi; Watanabe, Shigeru

    2003-01-01

    An Er:YAG laser effectively removes dental hard substance, and causes less pain during tooth preparations than high-speed drilling. This laser was introduced to eliminate the noise, vibration, pressure, and heat associated with the high-speed drilling. However, the difference in tooth vibration caused by the Er:YAG laser and the high-speed drill is unclear. Therefore, the aim of this study was to evaluate tooth vibration obtained with the Er:YAG laser and high-speed drill. Each of the five extracted permanent upper first premolars were built up in a plaster box. In this study, a silicone impression material was selected to simulate periodontal tissue. The vibration speed was measured by using a laser Doppler vibrometer. The Er:YAG laser irradiation energy was 50, 100, 145, 199, 300, and 350 mJ. As irradiation energy increased, vibration of the tooth also rose; a high-correlation coefficient was observed between them. We found that only a small amount of the tooth vibration occurred with the Er:YAG laser preparations. The mean vibration speed and standard deviation with the laser were 166 +/- 28 microm/second when the output energy was 145 mJ, whereas those with the high-speed drill were 65 +/- 48 mm/second. The frequency characteristic approached 230 Hz and 5 kHz, respectively. These results show that the high-speed drilling causes greater tooth vibration and has a frequency spectrum near the high sensitivity of hearing compared to the Er:YAG laser. This suggests a potential factor in provoking pain and displeasure during tooth preparation. Future study to examine the relationship of pain and amount of tooth vibration will be planned. Copyright 2003 Wiley-Liss, Inc.

  2. Laser micromachining as a metallization tool for microfluidic polymer stacks

    NASA Astrophysics Data System (ADS)

    Brettschneider, T.; Dorrer, C.; Czurratis, D.; Zengerle, R.; Daub, M.

    2013-03-01

    A novel assembly approach for the integration of metal structures into polymeric microfluidic systems is described. The presented production process is completely based on a single solid-state laser source, which is used to incorporate metal foils into a polymeric multi-layer stack by laser bonding and ablation processes. Chemical reagents or glues are not required. The polymer stack contains a flexible membrane which can be used for realizing microfluidic valves and pumps. The metal-to-polymer bond was investigated for different metal foils and plasma treatments, yielding a maximum peel strength of Rps = 1.33 N mm-1. A minimum structure size of 10 µm was determined by 3D microscopy of the laser cut line. As an example application, two different metal foils were used in combination to micromachine a standardized type-T thermocouple on a polymer substrate. An additional laser process was developed which allows metal-to-metal welding in close vicinity to the polymer substrate. With this process step, the reliability of the electrical contact could be increased to survive at least 400 PCR temperature cycles at very low contact resistances.

  3. Experimental investigation by laser ultrasonics for high speed train axle diagnostics.

    PubMed

    Cavuto, A; Martarelli, M; Pandarese, G; Revel, G M; Tomasini, E P

    2015-01-01

    The present paper demonstrates the applicability of a laser-ultrasonic procedure to improve the performances of train axle ultrasonic inspection. The method exploits an air-coupled ultrasonic probe that detects the ultrasonic waves generated by a high-power pulsed laser. As a result, the measurement chain is completely non-contact, from generation to detection, this making it possible to considerably speed up inspection time and make the set-up more flexible. The main advantage of the technique developed is that it works in thermo-elastic regime and it therefore can be considered as a non-destructive method. The laser-ultrasonic procedure investigated has been applied for the inspection of a real high speed train axle provided by the Italian railway company (Trenitalia), on which typical fatigue defects have been expressly created according to standard specifications. A dedicated test bench has been developed so as to rotate the axle with the angle control and to speed up the inspection of the axle surface. The laser-ultrasonic procedure proposed can be automated and is potentially suitable for regular inspection of train axles. The main achievements of the activity described in this paper are: – the study of the effective applicability of laser-ultrasonics for the diagnostic of train hollow axles with variable sections by means of a numerical FE model, – the carrying out of an automated experiment on a real train axle, – the analysis of the sensitivity to experimental parameters, like laser source – receiving probe distance and receiving probe angular position, – the demonstration that the technique is suitable for the detection of surface defects purposely created on the train axle.

  4. Progress and issues for high-speed vertical cavity surface emitting lasers

    NASA Astrophysics Data System (ADS)

    Lear, Kevin L.; Al-Omari, Ahmad N.

    2007-02-01

    Extrinsic electrical, thermal, and optical issues rather than intrinsic factors currently constrain the maximum bandwidth of directly modulated vertical cavity surface emitting lasers (VCSELs). Intrinsic limits based on resonance frequency, damping, and K-factor analysis are summarized. Previous reports are used to compare parasitic circuit values and electrical 3dB bandwidths and thermal resistances. A correlation between multimode operation and junction heating with bandwidth saturation is presented. The extrinsic factors motivate modified bottom-emitting structures with no electrical pads, small mesas, copper plated heatsinks, and uniform current injection. Selected results on high speed quantum well and quantum dot VCSELs at 850 nm, 980 nm, and 1070 nm are reviewed including small-signal 3dB frequencies up to 21.5 GHz and bit rates up to 30 Gb/s.

  5. Technology of High-speed Direct Laser Deposition from Ni-based Superalloys

    NASA Astrophysics Data System (ADS)

    Klimova-Korsmik, Olga; Turichin, Gleb; Zemlyakov, Evgeniy; Babkin, Konstantin; Petrovsky, Pavel; Travyanov, Andrey

    Recently, additive manufacturing is the one of most perspective technologies; it can replace conventional methods of casting and subsequent time-consuming machining. One of the most interesting additive technologies - high-speed direct laser deposition (HSDLD) allows realizing heterophase process during the manufacturing, which there is process takes place with a partial melting of powder. This is particularly important for materials, which are sensitive to strong fluctuations of temperature treatment regimes, like nickel base alloys with high content of gamma prime phase. This alloys are interested for many industrial areas, mostly there are used in engine systems, aircraft and shipbuilding, aeronautics. Heating and cooling rates during the producing process determine structure and affect on its properties. Using HSDLD process it possible to make a products from Ni superalloys with ultrafine microstructure and satisfactory mechanical characteristics without special subsequent heatreatment.

  6. High-speed laser-assisted cutting of strong transparent materials using picosecond Bessel beams

    NASA Astrophysics Data System (ADS)

    Bhuyan, M. K.; Jedrkiewicz, O.; Sabonis, V.; Mikutis, M.; Recchia, S.; Aprea, A.; Bollani, M.; Trapani, P. Di

    2015-08-01

    We report single-pass cutting of strong transparent glass materials of 700 μm thickness with a speed up to 270 mm/s using single-shot nanostructuring technique exploiting picosecond, zero-order Bessel beams at laser wavelength of 1030 nm. Particularly, we present results of a systematic study of cutting of tempered glass which has high resistance to thermal and mechanical shocks due to the inhomogeneous material properties along its thickness, and homogeneous glass that identify a unique focusing geometry and a finite pitch dependency, for which cutting with high quality and high reproducibility can be achieved. These results represent a significant advancement in the field of high-speed cutting of technologically important transparent materials.

  7. TOPICAL REVIEW: Biocavity laser for high-speed cell and tumour biology

    NASA Astrophysics Data System (ADS)

    Gourley, P. L.

    2003-07-01

    Through recent interdisciplinary scientific research, modern medicine has significantly advanced the diagnosis and treatment of disease. However, little progress has been made in reducing the death rate due to cancer, which remains the leading cause of death in much of the world. Pathologists rely on microscopic examination of cell morphology using methods that originated over a hundred years ago. These staining methods are labour-intensive, time-consuming, and sometimes in error. New micro-analytical methods for high speed (real-time) automated screening of tissues and cells could advance pathology and minimize cancer deaths. By teaming experts in physical/chemical sciences and engineering with those in medicine, it may be possible to develop micro-analytical cell spectral/imaging techniques to rapidly distinguish normal and abnormal cells. In this paper, we review the physics and applications of the biocavity laser which may enable these advances in the near future.

  8. High-Speed X-Ray Analysis of Spatter Formation in Laser Welding of Copper

    NASA Astrophysics Data System (ADS)

    Heider, A.; Sollinger, J.; Abt, F.; Boley, M.; Weber, R.; Graf, T.

    Due to their very good electrical and thermal conductivity copper materials are more and more demanded for industrial applications. For the assembly of copper based parts an effective and reliable welding process is required. At lower feed rates and high penetration depth respectively, welds in copper suffer from many weld defects such as pores and melt ejections. Keyhole instabilities during welding result in most cases in weld defects. In this paper high-speed X-ray imaging of the welding process is used to analyze keyhole instabilities with respect to the formation of weld defects. By means of X-ray observation of the welding process it is shown that bubble formation at the tip of the capillary is one mechanism which causes weld defects such as melt ejections and pores. Furthermore the influence of laser power modulation on bubble formation is discussed.

  9. A 5-mm piezo-scanning fiber device for high speed ultrafast laser microsurgery

    PubMed Central

    Ferhanoglu, Onur; Yildirim, Murat; Subramanian, Kaushik; Ben-Yakar, Adela

    2014-01-01

    Towards developing precise microsurgery tools for the clinic, we previously developed image-guided miniaturized devices using low repetition rate amplified ultrafast lasers for surgery. To improve the speed of tissue removal while reducing device diameter, here we present a new 5-mm diameter device that delivers high-repetition rate laser pulses for high speed ultrafast laser microsurgery. The device consists of an air-core photonic bandgap fiber (PBF) for the delivery of high energy pulses, a piezoelectric tube actuator for fiber scanning, and two aspheric lenses for focusing the light. Its inline optical architecture provides easy alignment and substantial size reduction to 5 mm diameter as compared to our previous MEMS-scanning devices while realizing improved intensity squared (two-photon) lateral and axial resolutions of 1.16 μm and 11.46 μm, respectively. Our study also sheds light on the maximum pulse energies that can be delivered through the air-core PBF and identifies cladding damage at the input facet of the fiber as the limiting factor. We have achieved a maximum energy delivery larger than 700 nJ at 92% coupling efficiency. An in depth analysis reveals how this value is greatly affected by possible slight misalignments of the beam during coupling and the measured small beam pointing fluctuations. In the absence of these imperfections, self-phase modulation becomes the limiting factor for the maximum energy delivery, setting the theoretical upper bound to near 2 μJ for a 1-m long, 7-μm, air-core PBF. Finally, the use of a 300 kHz repetition rate fiber laser enabled rapid ablation of 150 µm x 150 µm area within only 50 ms. Such ablation speeds can now allow the surgeons to translate the surgery device as fast as ~4 mm/s to continuously remove a thin layer of a 150 µm wide tissue. Thanks to a high optical transmission efficiency of the in-line optical architecture of the device and improved resolution, we could successfully perform ablation of

  10. Fast spectral coherent anti-Stokes Raman scattering microscopy with high-speed tunable picosecond laser.

    PubMed

    Cahyadi, Harsono; Iwatsuka, Junichi; Minamikawa, Takeo; Niioka, Hirohiko; Araki, Tsutomu; Hashimoto, Mamoru

    2013-09-01

    We develop a coherent anti-Stokes Raman scattering (CARS) microscopy system equipped with a tunable picosecond laser for high-speed wavelength scanning. An acousto-optic tunable filter (AOTF) is integrated in the laser cavity to enable wavelength scanning by varying the radio frequency waves applied to the AOTF crystal. An end mirror attached on a piezoelectric actuator and a pair of parallel plates driven by galvanometer motors are also introduced into the cavity to compensate for changes in the cavity length during wavelength scanning to allow synchronization with another picosecond laser. We demonstrate fast spectral imaging of 3T3-L1 adipocytes every 5  cm-1 in the Raman spectral region around 2850  cm-1 with an image acquisition time of 120 ms. We also demonstrate fast switching of Raman shifts between 2100 and 2850  cm-1, corresponding to CD2 symmetric stretching and CH2 symmetric stretching vibrations, respectively. The fast-switching CARS images reveal different locations of recrystallized deuterated and nondeuterated stearic acid.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  12. High-speed laser Doppler perfusion imaging using an integrating CMOS image sensor.

    PubMed

    Serov, Alexandre; Lasser, Theo

    2005-08-22

    This paper describes the design and the performance of a new high-speed laser Doppler imaging system for monitoring blood flow over an area of tissue. The new imager delivers high-resolution flow images (256x256 pixels) every 2 to 10 seconds, depending on the number of points in the acquired time-domain signal (32-512 points). This new imaging modality utilizes a digital integrating CMOS image sensor to detect Doppler signals in a plurality of points over the area illuminated by a divergent laser beam of a uniform intensity profile. The integrating property of the detector improves the signal-to-noise ratio of the measurements, which results in high-quality flow images. We made a series of measurements in vitro to test the performance of the system in terms of bandwidth, SNR, etc. Subsequently we give some examples of flow-related images measured on human skin, thus demonstrating the performance of the imager in vivo. The perspectives for future implementations of the imager for clinical and physiological applications are discussed.

  13. High-speed multi-frame laser Schlieren for visualization of explosive events

    NASA Astrophysics Data System (ADS)

    Clarke, S. A.; Murphy, M. J.; Landon, C. D.; Mason, T. A.; Adrian, R. J.; Akinci, A. A.; Martinez, M. E.; Thomas, K. A.

    2007-09-01

    High-Speed Multi-Frame Laser Schlieren is used for visualization of a range of explosive and non-explosive events. Schlieren is a well-known technique for visualizing shock phenomena in transparent media. Laser backlighting and a framing camera allow for Schlieren images with very short (down to 5 ns) exposure times, band pass filtering to block out explosive self-light, and 14 frames of a single explosive event. This diagnostic has been applied to several explosive initiation events, such as exploding bridgewires (EBW), Exploding Foil Initiators (EFI) (or slappers), Direct Optical Initiation (DOI), and ElectroStatic Discharge (ESD). Additionally, a series of tests have been performed on "cut-back" detonators with varying initial pressing (IP) heights. We have also used this Diagnostic to visualize a range of EBW, EFI, and DOI full-up detonators. The setup has also been used to visualize a range of other explosive events, such as explosively driven metal shock experiments and explosively driven microjets. Future applications to other explosive events such as boosters and IHE booster evaluation will be discussed. Finite element codes (EPIC, CTH) have been used to analyze the schlieren images to determine likely boundary or initial conditions to determine the temporal-spatial pressure profile across the output face of the detonator. These experiments are part of a phased plan to understand the evolution of detonation in a detonator from initiation shock through run to detonation to full detonation to transition to booster and booster detonation.

  14. A study of laser-plasma expansion into the background gas by means of high-speed photography

    NASA Astrophysics Data System (ADS)

    Anan'in, O. B.; Bykovskii, Iu. A.; Eremin, Iu. V.; Stupitskii, E. L.; Novikov, I. K.; Frolov, S. P.

    1991-07-01

    A method for studying laser-plasma behavior in a vacuum and in a background gas by means of high-speed photography is presented. Photographs of laser-plasma expansion into the background gas at different pressures are analyzed. The detection of hydrodynamic instability of the laser plasma front during expansion into the background gas is reported. A theoretical analysis of the experimental results is presented.

  15. High-speed laser microsurgery of alert fruit flies for fluorescence imaging of neural activity

    PubMed Central

    Sinha, Supriyo; Liang, Liang; Ho, Eric T. W.; Urbanek, Karel E.; Luo, Liqun; Baer, Thomas M.; Schnitzer, Mark J.

    2013-01-01

    Intravital microscopy is a key means of monitoring cellular function in live organisms, but surgical preparation of a live animal for microscopy often is time-consuming, requires considerable skill, and limits experimental throughput. Here we introduce a spatially precise (<1-µm edge precision), high-speed (<1 s), largely automated, and economical protocol for microsurgical preparation of live animals for optical imaging. Using a 193-nm pulsed excimer laser and the fruit fly as a model, we created observation windows (12- to 350-µm diameters) in the exoskeleton. Through these windows we used two-photon microscopy to image odor-evoked Ca2+ signaling in projection neuron dendrites of the antennal lobe and Kenyon cells of the mushroom body. The impact of a laser-cut window on fly health appears to be substantially less than that of conventional manual dissection, for our imaging durations of up to 18 h were ∼5–20 times longer than prior in vivo microscopy studies of hand-dissected flies. This improvement will facilitate studies of numerous questions in neuroscience, such as those regarding neuronal plasticity or learning and memory. As a control, we used phototaxis as an exemplary complex behavior in flies and found that laser microsurgery is sufficiently gentle to leave it intact. To demonstrate that our techniques are applicable to other species, we created microsurgical openings in nematodes, ants, and the mouse cranium. In conjunction with emerging robotic methods for handling and mounting flies or other small organisms, our rapid, precisely controllable, and highly repeatable microsurgical techniques should enable automated, high-throughput preparation of live animals for optical experimentation. PMID:24167298

  16. High-speed laser microsurgery of alert fruit flies for fluorescence imaging of neural activity.

    PubMed

    Sinha, Supriyo; Liang, Liang; Ho, Eric T W; Urbanek, Karel E; Luo, Liqun; Baer, Thomas M; Schnitzer, Mark J

    2013-11-12

    Intravital microscopy is a key means of monitoring cellular function in live organisms, but surgical preparation of a live animal for microscopy often is time-consuming, requires considerable skill, and limits experimental throughput. Here we introduce a spatially precise (<1-µm edge precision), high-speed (<1 s), largely automated, and economical protocol for microsurgical preparation of live animals for optical imaging. Using a 193-nm pulsed excimer laser and the fruit fly as a model, we created observation windows (12- to 350-µm diameters) in the exoskeleton. Through these windows we used two-photon microscopy to image odor-evoked Ca(2+) signaling in projection neuron dendrites of the antennal lobe and Kenyon cells of the mushroom body. The impact of a laser-cut window on fly health appears to be substantially less than that of conventional manual dissection, for our imaging durations of up to 18 h were ∼5-20 times longer than prior in vivo microscopy studies of hand-dissected flies. This improvement will facilitate studies of numerous questions in neuroscience, such as those regarding neuronal plasticity or learning and memory. As a control, we used phototaxis as an exemplary complex behavior in flies and found that laser microsurgery is sufficiently gentle to leave it intact. To demonstrate that our techniques are applicable to other species, we created microsurgical openings in nematodes, ants, and the mouse cranium. In conjunction with emerging robotic methods for handling and mounting flies or other small organisms, our rapid, precisely controllable, and highly repeatable microsurgical techniques should enable automated, high-throughput preparation of live animals for optical experimentation.

  17. World record in high speed laser surface microstructuring of polymer and steel using direct laser interference patterning

    NASA Astrophysics Data System (ADS)

    Lang, Valentin; Roch, Teja; Lasagni, Andrés. F.

    2016-03-01

    Periodic surfaces structures with micrometer or submicrometer resolution produced on the surface of components can be used to improve their mechanical, biological or optical properties. In particular, these surfaces can control the tribological performance of parts, for instance in the automotive industry. In the last years, substantial efforts have been made to develop new technologies capable to produce functionalized surfaces. One of these technologies is the Direct Laser Interference Patterning (DLIP) technology, which permits to combine high fabrication speed with high resolution even in the sub-micrometer range. In DLIP, a laser beam is split into two or more coherent beams which are guided to interfere on the work piece surface. This causes modulated laser intensities over the component's surface, enabling the direct fabrication of a periodic pattern based on selective laser ablation or melting. Depending on the angle between the laser beams and the wavelength of the laser, the pattern's spatial period can be perfectly controlled. In this study, we introduce new modular DLIP optical heads, developed at the Fraunhofer IWS and the Technische Universität Dresden for high-speed surface laser patterning of polymers and metals. For the first time it is shown that effective patterning speeds of up to 0.90 m2/min and 0.36 m2/min are possible on polymer and metals, respectively. Line- and dot-like surface architectures with spatial periods between 7 μm and 22 μm are shown.

  18. A laser-induced heat flux technique for convective heat transfer measurements in high speed flows

    NASA Technical Reports Server (NTRS)

    Porro, A. R.; Keith, T. G., Jr.; Hingst, W. R.

    1991-01-01

    A technique is developed to measure the local convective heat transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local heat flux at the model test surface, and an infrared camera system determines the local temperature distribution due to the heating. From this temperature distribution and an analysis of the heating process, a local convective heat transfer coefficient is determined. The technique was used to measure the local surface convective heat transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective heat transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective heat transfer coefficients in high speed flow fields.

  19. A laser-induced heat flux technique for convective heat transfer measurements in high speed flows

    NASA Technical Reports Server (NTRS)

    Porro, A. R.; Keith, T. G., Jr.; Hingst, W. R.

    1991-01-01

    A technique is developed to measure the local convective heat transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local heat flux at the model test surface, and an infrared camera system determines the local temperature distribution due to the heating. From this temperature distribution and an analysis of the heating process, a local convective heat transfer coefficient is determined. The technique was used to measure the local surface convective heat transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective heat transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective heat transfer coefficients in high-speed flowfields.

  20. Characterization of a fast CMOS imaging sensor for high-speed laser detection

    NASA Astrophysics Data System (ADS)

    Casadei, Bruno; Le Normand, J. P.; Hu, Y.; Cunin, Bernard

    2003-07-01

    CMOS active pixel sensors (APS) have performances competitive with charge-coupled device (CCD) technology, and offer advantages in on-chip functionality, system power reduction, cost and miniaturization. In this paper, we present characterization of a fast CMOS APS used in an imager for high-speed laser detections, which can replace the streak cameras. It produces the intensity information in function of one spatial dimension and time [I = f(x,t)] from one frame in two spatial dimensions. The time information is obtained for the first prototype camera to delay successively the integration phase in each pixel of the same row. The different noise sources of the APS sensors such as shot noise due to the photo sensor, the thermal noise and flicker noise due to the readout transistors and the photon shot noise are presented to determine the fundamental limits on image sensor. The first prototype FAMOSI (FAst MOS Imager) is composed of 64 x 64 active pixels. The simulation and experimental results show that a conversion gain of 6.73 +/- 0.25 μV/e- has been obtained with a noise level of 87 +/- 3e- rms. The power consumption of the chip is 25 mW at 50 images/sec.

  1. Investigating high speed phenomena in laser plasma interactions using dilation x-ray imager (invited)

    SciTech Connect

    Nagel, S. R. Bell, P. M.; Bradley, D. K.; Ayers, M. J.; Piston, K.; Felker, B.; Hilsabeck, T. J.; Kilkenny, J. D.; Chung, T.; Sammuli, B.; Hares, J. D.; Dymoke-Bradshaw, A. K. L.

    2014-11-15

    The DIlation X-ray Imager (DIXI) is a new, high-speed x-ray framing camera at the National Ignition Facility (NIF) sensitive to x-rays in the range of ≈2–17 keV. DIXI uses the pulse-dilation technique to achieve a temporal resolution of less than 10 ps, a ≈10× improvement over conventional framing cameras currently employed on the NIF (≈100 ps resolution), and otherwise only attainable with 1D streaked imaging. The pulse-dilation technique utilizes a voltage ramp to impart a velocity gradient on the signal-bearing electrons. The temporal response, spatial resolution, and x-ray sensitivity of DIXI are characterized with a short x-ray impulse generated using the COMET laser facility at Lawrence Livermore National Laboratory. At the NIF a pinhole array at 10 cm from target chamber center (tcc) projects images onto the photocathode situated outside the NIF chamber wall with a magnification of ≈64×. DIXI will provide important capabilities for warm-dense-matter physics, high-energy-density science, and inertial confinement fusion, adding important capabilities to temporally resolve hot-spot formation, x-ray emission, fuel motion, and mix levels in the hot-spot at neutron yields of up to 10{sup 17}. We present characterization data as well as first results on electron-transport phenomena in buried-layer foil experiments.

  2. High speed ultra short pulse fiber ring laser using photonic crystal fiber nonlinear optical loop mirror

    NASA Astrophysics Data System (ADS)

    Ma, Shaozhen; Li, Wenbo; Hu, Hongyu; Dutta, Niloy K.

    2012-06-01

    A scheme to generate high speed optical pulse train with ultra short pulse width is proposed and experimentally studied. Two-step compression is used in the scheme: 20 GHz and 40 GHz pulse trains generated from a rational harmonic actively mode-locked fiber ring laser is compressed to a full width at half-maximum (FWHM) of ~ 1.5 ps using adiabatic soliton compression with dispersion shifted fibers (DSF). The pulse trains then undergo a pedestal removal process by transmission through a cascaded two photonic crystal fiber (PCF)-nonlinear optical loop mirrors (NOLM) realized using a double-ring structure. The shortest output pulse width obtained was ~ 610 fs for 20 GHz pulse train and ~ 570 fs for 40 GHz pulse train. The signal to noise ratio of the RF spectrum of the output pulse train is larger than 30 dB. Theoretical simulation of the NOLM transmission is conducted using split-step Fourier method. The results show that two cascaded NOLMs can improve the compression result compared to that for a single NOLM transmission.

  3. A laser-induced heat flux technique for convective heat transfer measurements in high speed flows

    NASA Technical Reports Server (NTRS)

    Porro, A. R.; Keith, T. G., Jr.; Hingst, W. R.

    1991-01-01

    A technique is developed to measure the local convective heat transfer coefficient on a model surface in a supersonic flow field. The technique uses a laser to apply a discrete local heat flux at the model test surface, and an infrared camera system determines the local temperature distribution due to the heating. From this temperature distribution and an analysis of the heating process, a local convective heat transfer coefficient is determined. The technique was used to measure the local surface convective heat transfer coefficient distribution on a flat plate at nominal Mach numbers of 2.5, 3.0, 3.5, and 4.0. The flat plate boundary layer initially was laminar and became transitional in the measurement region. The experimentally determined convective heat transfer coefficients were generally higher than the theoretical predictions for flat plate laminar boundary layers. However, the results indicate that this nonintrusive optical measurement technique has the potential to measure surface convective heat transfer coefficients in high-speed flowfields.

  4. High-speed laser ablation of metal with pico- and subpicosecond pulses

    NASA Astrophysics Data System (ADS)

    Mazhukin, V. I.; Demin, M. M.; Shapranov, A. V.

    2014-05-01

    The mechanism of the high-speed ablation of aluminum with pico- and subpicosecond (10-11-10-13 s) laser pulses is considered. Mathematical modeling based on the continuum non-equilibrium two-temperature (TTM) model revealed that in a relatively narrow range of fluence 0.25-0.7 J/cm2, the regime of mechanical fragmentation of the irradiated surface is realized. The maximum values of the lattice temperature for the specified range of fluence are 2100-3500 K. The removal of the material is mechanical due to the negative stresses in the rarefaction wave following the shock wave. Explicit tracking of temporal and spatial position of the melting front has allowed establishing its role in the generation of superheated metastable states in the solid phase and the propagation of the shock wave. The removed material with total thickness of 60-100 nm is a collection of separate plates with thickness from 1 nm to 55 nm.

  5. Dynamics of water-mediated hard dental tissue ablation with Ho:YAG laser visualized by high speed photography

    NASA Astrophysics Data System (ADS)

    Zhan, Zhenlin; Chen, Chuanguo; Li, Xuwei; Zhang, Xianzeng; Xie, Shusen

    2015-03-01

    The goal of this study was to evaluate the dynamic process of water-mediated hard dental tissue ablation induced by Ho:YAG laser with high-speed camera. Human molars in vitro of yellow race were cut into tooth sections and irradiated with pulsed Ho:YAG laser with a wavelength of 2.08μm. The pulse repetition rate was 3 Hz and laser energy ranged from 300 to 2000 mJ. The frame rate of high-speed camera used in the experiment was 50525 fps. Based on the observation by high-speed camera, the dynamic process of the oscillating cavitation bubble and water-mediated ablation induced by Ho:YAG laser was efficiently recorded and graphically described. The pulsation period, the maximum length and width of vapor channel increased with laser energy. The results showed that the external water played multiple roles in laser ablation of hard dental tissue, not only acting as a channel to transmit laser energy, but also helping to improve the regularity of the ablation shape.

  6. Turbulence measurements in high-speed wind tunnels using focusing laser differential interferometry

    NASA Astrophysics Data System (ADS)

    Fulghum, Matthew R.

    Characterization of freestream disturbances and their effect on laminar boundary layer transition is of great importance in high-speed wind tunnel testing, where significant differences between the behavior of scale-model and free-flight transition have long been noted. However, the methods traditionally used to perform this characterization in low-speed flows present significant difficulties when applied to supersonic and especially hypersonic wind tunnels. The design and theory of a focusing laser differential interferometer (FLDI) instrument, originally invented by Smeets at the Institut Saint-Louis in the 1970s and used recently by Parziale in the CalTech T5 shock tunnel, is presented. It is a relatively-simple, non-imaging common-path interferometer for measuring refractive signals from transition and turbulence, and it has a unique ability to look through facility windows, ignore sidewall boundary-layers and vibration, and concentrate only on the refractive signal near a pair of sharp beam foci in the core flow. The instrument's low cost and ease of implementation make it a promising alternative to traditional hot-wire anemometry and particle-based methods for turbulence characterization. Benchtop experiments using a turbulent supersonic air jet demonstrate its focusing ability, frequency response, unwanted signal rejection, and ease of use. The instrument is used to optically interrogate the flow in the Penn State University Supersonic Wind Tunnel and USAF AEDC Hypervelocity Tunnel 9 for measurement of the overall intensity and spectra of freestream disturbances. Precise characterization of the strength and spectral content of the disturbances provides insight into their nature and potential effect upon boundary layer transition. A special feature of the FLDI instrument used here is the replacement of traditional fixed Wollaston prisms with variable Sanderson prisms for laser-beam separation and recombination.

  7. Optoelectronic measurement for parameters of high-speed flying objects based on laser screen and photodiode array

    NASA Astrophysics Data System (ADS)

    Zhao, Donge; Zhang, Bin; Liu, Ji; Xiao, Kai-jia; Wang, Lei

    2013-09-01

    The impacting or penetrating power of high-speed flying object can be evaluated by its mass and velocity, so the velocity and the mass are two key parameters. Here we present an optoelectronic measurement method for parameters of high-speed flying objects based on parallel laser screen and photodiode array. The system consists of two thin laser screens with parallel each other and certain distance, orthogonal two dimensional photodiode arrays, data acquisition module, control module and data transmission processing module. When the object flies through the thin screen, the incident light of some photodiodes at the corresponding position is blocked and the output states of the corresponding photodiodes are changed. The flying position, which can be used to correct the distance error, velocity and the overall dimension of the object are determined by high-speed sampling and storing all the output states of photodiode array at any sampling moment when the object flying through the thin screens. We employed a line-shaped laser diode and a Fresnel lens with long-focal-length and aberration-free to generate parallel laser screen. The high-speed large-amount parallel data sampling module is comprised of four FPGA-based boards with built-in FIFO buffer memory, and the control module is constructed by one FPGA board and a FLASH memory. Functions simulation and experiment results of the FPGA-based data acquisition storage and the LabVIEW-based data processing indicate that the method and the design are feasible.

  8. Comparison of high speed imaging technique to laser vibrometry for detection of vibration information from objects

    NASA Astrophysics Data System (ADS)

    Paunescu, Gabriela; Lutzmann, Peter; Göhler, Benjamin; Wegner, Daniel

    2015-10-01

    The development of camera technology in recent years has made high speed imaging a reliable method in vibration and dynamic measurements. The passive recovery of vibration information from high speed video recordings was reported in several recent papers. A highly developed technique, involving decomposition of the input video into spatial subframes to compute local motion signals, allowed an accurate sound reconstruction. A simpler technique based on image matching for vibration measurement was also reported as efficient in extracting audio information from a silent high speed video. In this paper we investigate and discuss the sensitivity and the limitations of the high speed imaging technique for vibration detection in comparison to the well-established Doppler vibrometry technique. Experiments on the extension of the high speed imaging method to longer range applications are presented.

  9. Thermoelectric Device Fabrication Using Thermal Spray and Laser Micromachining

    NASA Astrophysics Data System (ADS)

    Tewolde, Mahder; Fu, Gaosheng; Hwang, David J.; Zuo, Lei; Sampath, Sanjay; Longtin, Jon P.

    2016-02-01

    Thermoelectric generators (TEGs) are solid-state devices that convert heat directly into electricity. They are used in many engineering applications such as vehicle and industrial waste-heat recovery systems to provide electrical power, improve operating efficiency and reduce costs. State-of-art TEG manufacturing is based on prefabricated materials and a labor-intensive process involving soldering, epoxy bonding, and mechanical clamping for assembly. This reduces their durability and raises costs. Additive manufacturing technologies, such as thermal spray, present opportunities to overcome these challenges. In this work, TEGs have been fabricated for the first time using thermal spray technology and laser micromachining. The TEGs are fabricated directly onto engineering component surfaces. First, current fabrication techniques of TEGs are presented. Next, the steps required to fabricate a thermal spray-based TEG module, including the formation of the metallic interconnect layers and the thermoelectric legs are presented. A technique for bridging the air gap between two adjacent thermoelectric elements for the top layer using a sacrificial filler material is also demonstrated. A flat 50.8 mm × 50.8 mm TEG module is fabricated using this method and its performance is experimentally characterized and found to be in agreement with expected values of open-circuit voltage based on the materials used.

  10. Pulsed laser micromachining of Mg-Cu-Gd bulk metallic glass

    NASA Astrophysics Data System (ADS)

    Lin, Hsuan-Kai; Lee, Ching-Jen; Hu, Ting-Ting; Li, Chun-Han; Huang, J. C.

    2012-06-01

    Micromachining of Mg-based bulk metallic glasses (BMGs) is performed using two kinds of pulsed nanosecond lasers: a 355 nm ultraviolet (UV) laser and a 1064 nm infrared (IR) laser. Precision machining on the micrometer scale and the preservation of amorphous or short-range order characteristics are important for the application of BMGs in micro-electro-mechanical systems. A higher micromachining rate is achieved using the UV laser than using the IR laser due to a better absorption rate of the former by Mg-based BMGs and a higher photon energy. The cutting depth of Mg-based BMGs ranges from 1 to 80 μm depending on the laser parameters. By appropriate adjustment of the laser power and scan speed, successful machining of the Mg-based BMG with preservation of the amorphous phase is achieved after the laser irradiation process. Short-pulse laser cutting represents a suitable alternative for machining of micro components.

  11. Rapid prototyping of a micro pump with laser micromachining

    NASA Astrophysics Data System (ADS)

    Wong, C. Channy; Chu, Dahwey; Liu, Sally L.; Tuck, Melanie R.; Mahmud, Zahid; Amatucci, Vincent A.

    1995-09-01

    A microelectrohydrodynamic (EHD) injection pump has been developed using laser micromachining technoogy. Two desings have been fabricated, tested, and evaluated. The first design has two silicon pieces with KOH-etched wells which are stacked on the tpo of each other. The wells are etched on one side of the wafer and gold is deposited on the other side to serve as the pump electrodes. A Nd:YAG laser is used to drill an array of circular holes in the well region of both silicon parts. This creates a grid distribution with a square pattern. Next the well regions of the silicon parts are aligned, and the parts are bonded together using a Staystik thermoplastic. The pump unit is then mounted into a ceramic package with a large hole drilled in the bottom of the package to permit fluid flow. Aluminum ribbon wire bonds are used to connect the pump electrodes to the package leads. Isolation of metallization and wires is achieved by filling the package well and coating the wires with polyimide. When a voltage is applied at the electrodes, ions are injected into the working fluid, such as an organic solvent, thus inducing flow. The second design has the silicon parts oriented 'back-to-back' and bonded together with Stayform. A 'back-to-back' design will decrease the grid distance so that a smaller voltage is required for pumping. Preliminary results have demonstrated that this micropump can achieve a pressure head of about 287 Pa with an applied voltage of 120 Volt.

  12. Transportable optical ground station for high-speed free-space laser communication

    NASA Astrophysics Data System (ADS)

    Shrestha, Amita; Brechtelsbauer, Martin

    2012-10-01

    Near real-time data downlinks from aircrafts, satellites and high altitude platforms via high-speed laser commu- nication links is an important research topic at the Institute of Communications and Navigation of the German Aerospace Center (DLR). Ground stations for such scenarios are usually fixed at a certain location. With a mo- tivation to provide a ground station that is quickly and easily deployed anywhere in the world, a transportable optical ground station (TOGS) has been developed. TOGS features a pneumatically deployable Cassegrain-type telescope with main mirror diameter of 60 cm, including optical tracking and receiving system. For calibration of position and attitude, multiple sensors like dual-antenna GPS and inclination sensors have been installed. In order to realize these systems, robust software that operates and controls them is essential. The software is platform independent and is aimed to be used on both mobile and ground terminals. It includes implementa- tion of accurate pointing, acquisition and tracking algorithms, hardware drivers, and user interfaces. Important modules of the software are GPS tracking, optical tracking, star- and satellite tracking, and calibration of the TOGS itself. Recently, a first successful data-downlink from an aircraft to TOGS using GPS tracking has been performed. To streamline the software development and testing process, some simulation environments like mount simulator, aircraft path simulator, tracking camera simulator and tracking error analysis tool have also been developed. This paper presents the overall hardware/software structure of the TOGS, and gives results of the tracking accuracy improvement techniques like GPS extrapolation and optical tracking.

  13. High-Speed Photography

    SciTech Connect

    Paisley, D.L.; Schelev, M.Y.

    1998-08-01

    The applications of high-speed photography to a diverse set of subjects including inertial confinement fusion, laser surgical procedures, communications, automotive airbags, lightning etc. are briefly discussed. (AIP) {copyright} {ital 1998 Society of Photo-Optical Instrumentation Engineers.}

  14. Techniques and applications for integrating a semiconductor laser on a micromachined die

    NASA Astrophysics Data System (ADS)

    Bouchard, Joseph G., Jr.; Bright, Victor M.; Burns, David M.

    1998-04-01

    This paper describes methods for attaching a vertical cavity surface emitting laser (VCSEL) on to a surface micromachined die. Techniques investigated include silver paste, soldering, wire bonding, and gold pads with integrated resistive heaters. Each technique is evaluated based on reliability, positioning tolerances, and secondary effects. Applications include single chip laser beam scanning.

  15. High-speed and wide bandwidth Fourier domain mode-locked wavelength swept laser with multiple SOAs.

    PubMed

    Jeon, Min Yong; Zhang, Jun; Wang, Qiang; Chen, Zhongping

    2008-02-18

    We report on the development of a high-speed, wide bandwidth Fourier domain mode-locked (FDML) wavelength swept laser of around 1300 nm using two gain media for high-resolution and high-speed Fourier domain optical coherence tomography. The wavelength swept laser is capable of FWHM scanning range of more than 135 nm at 45.6 kHz sweeping rate. The measured axial resolution of the forward scan is 6.6 microm in air and 4.7 microm in tissue. The peak power is 11.4 mW for both the forward and backward scans. The measured system sensitivity is achieved up to 100.7 dB. We also demonstrate OCT imaging using the FDML wavelength swept laser with two semiconductor optical amplifiers.

  16. Femtosecond laser micromachined ridge waveguide lasers in Nd:YAG ceramics

    NASA Astrophysics Data System (ADS)

    Jia, Yuechen; Vázquez de Aldana, Javier R.; Akhmadaliev, Shavkat; Zhou, Shengqiang; Chen, Feng

    2013-12-01

    We report on the fabrication of ridge waveguides in Nd:YAG ceramic by using femtosecond laser micromachining of the surface of a He ion implanted planar waveguide. Under optical pump of 808 nm light, continuous wave waveguide lasers have been realized at 1.06 μm at room temperature in the Nd:YAG ceramic ridge waveguide system, reaching a maximum output power of 46 mW. The lasing threshold of ˜64.9 mW and the slope efficiency of 42.5% are obtained for the ridge waveguide system, which shows superior lasing performance to the Nd:YAG ceramic planar waveguide.

  17. A high-speed acquisition and processing system of the laser speckle signal on the magnetic fluid

    NASA Astrophysics Data System (ADS)

    Wan, Qiu-hua; Jiang, Yong; Su, Shao-chang; Sun, Ying; Wu, Yong-zhi

    2009-07-01

    In order to achieve the dynamical detection and real-time analysis of the movement status of the magnetic fluid, according to the difficulties of the detection of the magnetic fluid, established a high-speed acquisition and processing system of laser speckle signal on the magnetic fluid. First of all, the FPGA (EP2C8T144C8N) drived the linear array CCD(TCD1501D) to scan in the corresponding time sequence given by the computer, collected the laser speckle interferometric image in rapid change on the surface of the magnetic fluid, which followed the movement of the magnetic fluid, and the signal collected by CCD was converted into the digital data through the high-speed A/D convertor and stored into the internal buffer FIFO of the FPGA, whose width and depth were designed by the user as required. Then, the FPGA sent the digital signal of the laser speckle interferometric images into the computer through the USB2.0 highspeed differential bus, whose transmission rate can reach 480Mb/s in theory. Finally, the distribution of the laser speckle on the magnetic fluid was messy and random, which carried certain information about the surface of the magnetic fluid, based on the theories of the statistic correlation and the subdivision of images, analysing and processing the laser speckle interferometric images, indirectly got the movement status of the magnetic fluid under the electromagnetic field. The experimental results show that: the High Speed Acquisition and Processing System has the advantage of full-court, non-contact, non-invasive, high-precision and high reliability and so on. The detection resolution of high speed acquisition and processing system is superior to 1m and the sample rate is 3Msps, which basically meets the requirements of the magnetic fluid movement state detection.

  18. High speed, intermediate resolution, large area laser beam induced current imaging and laser scribing system for photovoltaic devices and modules.

    PubMed

    Phillips, Adam B; Song, Zhaoning; DeWitt, Jonathan L; Stone, Jon M; Krantz, Patrick W; Royston, John M; Zeller, Ryan M; Mapes, Meghan R; Roland, Paul J; Dorogi, Mark D; Zafar, Syed; Faykosh, Gary T; Ellingson, Randy J; Heben, Michael J

    2016-09-01

    We have developed a laser beam induced current imaging tool for photovoltaic devices and modules that utilizes diode pumped Q-switched lasers. Power densities on the order of one sun (100 mW/cm(2)) can be produced in a ∼40 μm spot size by operating the lasers at low diode current and high repetition rate. Using galvanostatically controlled mirrors in an overhead configuration and high speed data acquisition, large areas can be scanned in short times. As the beam is rastered, focus is maintained on a flat plane with an electronically controlled lens that is positioned in a coordinated fashion with the movements of the mirrors. The system can also be used in a scribing mode by increasing the diode current and decreasing the repetition rate. In either mode, the instrument can accommodate samples ranging in size from laboratory scale (few cm(2)) to full modules (1 m(2)). Customized LabVIEW programs were developed to control the components and acquire, display, and manipulate the data in imaging mode.

  19. High speed, intermediate resolution, large area laser beam induced current imaging and laser scribing system for photovoltaic devices and modules

    NASA Astrophysics Data System (ADS)

    Phillips, Adam B.; Song, Zhaoning; DeWitt, Jonathan L.; Stone, Jon M.; Krantz, Patrick W.; Royston, John M.; Zeller, Ryan M.; Mapes, Meghan R.; Roland, Paul J.; Dorogi, Mark D.; Zafar, Syed; Faykosh, Gary T.; Ellingson, Randy J.; Heben, Michael J.

    2016-09-01

    We have developed a laser beam induced current imaging tool for photovoltaic devices and modules that utilizes diode pumped Q-switched lasers. Power densities on the order of one sun (100 mW/cm2) can be produced in a ˜40 μm spot size by operating the lasers at low diode current and high repetition rate. Using galvanostatically controlled mirrors in an overhead configuration and high speed data acquisition, large areas can be scanned in short times. As the beam is rastered, focus is maintained on a flat plane with an electronically controlled lens that is positioned in a coordinated fashion with the movements of the mirrors. The system can also be used in a scribing mode by increasing the diode current and decreasing the repetition rate. In either mode, the instrument can accommodate samples ranging in size from laboratory scale (few cm2) to full modules (1 m2). Customized LabVIEW programs were developed to control the components and acquire, display, and manipulate the data in imaging mode.

  20. High speed imaging of an Er,Cr:YSGG laser in a model of a root canal

    NASA Astrophysics Data System (ADS)

    Verdaasdonk, Rudolf; Blanken, Jan; van Heeswijk, Hans; de Roode, Rowland; Klaessens, John

    2007-02-01

    Laser systems of various wavelengths and pulse characteristics have been introduced in dentistry. At present, the range of applications for the different systems is being investigated mainly differentiating between soft and hard tissue applications. For the preparation of root canals both hard and soft tissues are involved. Ideally, one would like to use one laser system for the whole treatment. In this study, we studied the characteristics of the pulsed 2,78 Er,Cr:YSGG laser (Biolase, Waterlase Millenium), in view of root canal cleaning and desinfection. The laser energy was fiber delivered with fiber tip diameters from 400 μm down to 200 μm. Special thermal and high speed imaging techniques were applied in a transparent model of a tapered root canal and slices cut from human teeth. High speed imaging revealed the dynamics of an explosive vapor bubble at the tip of the Er laser in water and the root canal model. Typically for Erbium lasers, within a time span of several hundred μs, a longitudinal bubble expanded to maximum size of 5 mm length and 2 mm diameter at 100 mJ and imploded afterwards. In the root canal, the explosive bubble created turbulent high speed water streaming which resects soft tissue from the hard tissue. Thermal imaging showed the dynamics of all lasers heating of the canal wall up to several mm depending on the wavelength and energy settings. The mechanism of smear layer removal and sterilization in the root canal, is attributed to cavitation effects induced by the pulsed laser. The heat generation into the dentine wall was minimal.

  1. Calibration of ultra high speed laser engraving processes by correlating influencing variables including correlative evaluation with SEM and CLSM

    NASA Astrophysics Data System (ADS)

    Bohrer, Markus; Vaupel, Matthias; Nirnberger, Robert; Weinberger, Bernhard

    2016-03-01

    Laser engraving is used for decades as a well-established process e. g. for the production of print and embossing forms for many goods in daily life, e. g. decorated cans and printed bank notes. Up to now it is more or less a so-called fire-and-forget process. From the original artist's plan to the digitization, then from the laser source itself (with electronic signals, RF and plasma discharge regarding CO2 lasers) to the behavior of the optical beam delivery — especially if an AOM is used — to the interaction of the laser beam with the material itself is a long process chain. The most recent results using CO2 lasers with AOMs and the research done with scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM) — as a set for correlative microscopy to evaluate the high speed engraving characteristics — are presented in this paper.

  2. Modelling of micromachining of human tooth enamel by erbium laser radiation

    SciTech Connect

    Belikov, A V; Skrypnik, A V; Shatilova, K V

    2014-08-31

    We consider a 3D cellular model of human tooth enamel and a photomechanical cellular model of enamel ablation by erbium laser radiation, taking into account the structural peculiarities of enamel, energy distribution in the laser beam cross section and attenuation of laser energy in biological tissue. The surface area of the texture in enamel is calculated after its micromachining by erbium laser radiation. The influence of the surface area on the bond strength of enamel with dental filling materials is discussed. A good correlation between the computer simulation of the total work of adhesion and experimentally measured bond strength between the dental filling material and the tooth enamel after its micromachining by means of YAG : Er laser radiation is attained. (laser biophotonics)

  3. Modelling of micromachining of human tooth enamel by erbium laser radiation

    NASA Astrophysics Data System (ADS)

    Belikov, A. V.; Skrypnik, A. V.; Shatilova, K. V.

    2014-08-01

    We consider a 3D cellular model of human tooth enamel and a photomechanical cellular model of enamel ablation by erbium laser radiation, taking into account the structural peculiarities of enamel, energy distribution in the laser beam cross section and attenuation of laser energy in biological tissue. The surface area of the texture in enamel is calculated after its micromachining by erbium laser radiation. The influence of the surface area on the bond strength of enamel with dental filling materials is discussed. A good correlation between the computer simulation of the total work of adhesion and experimentally measured bond strength between the dental filling material and the tooth enamel after its micromachining by means of YAG : Er laser radiation is attained.

  4. Two-dimensional differential adherence of neuroblasts in laser micromachined CAD/CAM agarose channels

    NASA Astrophysics Data System (ADS)

    Doraiswamy, A.; Patz, T.; Narayan, R. J.; Dinescu, M.; Modi, R.; Auyeung, R. C. Y.; Chrisey, D. B.

    2006-04-01

    Laser micromachining of hydrophobic gels into CAD/CAM patterns was used to develop differentially adherent surfaces and induce the attachment of B35 rat neuroblasts that would later form engineered nerve bundles. Narrow channels, 60-400 μm wide, were micromachined in a 2% agarose gel using an ArF laser, and subsequently filled with an extracellular matrix gel. Upon the addition of 1 ml of a 2 × 104 cells/ml neuroblast suspension, the cells selectively adhered to the ECM-lined channels in a non-confluent manner and we monitored their growth at various time points. The adherent neuroblasts were fluorescently imaged with a propidium iodide live/dead assay, which revealed that the cells were alive within the channels. After 72 h growth, the neuroblasts grew, proliferated, and differentiated into nerve bundles. The fully grown 1 cm long nerve bundle organoids maintained an aspect ratio on the order of 100. The results presented in this paper provide the foundation for laser micromachining technique to develop bioactive substrates for development of three-dimensional tissues. Laser micromachining offers rapid prototyping of substrates, excellent resolution, control of pattern depth and dimensions, and ease of fabrication.

  5. High-speed two-dimensional laser scanner based on Bragg gratings stored in photothermorefractive glass.

    PubMed

    Yaqoob, Zahid; Arain, Muzammil A; Riza, Nabeel A

    2003-09-10

    A high-speed free-space wavelength-multiplexed optical scanner with high-speed wavelength selection coupled with narrowband volume Bragg gratings stored in photothermorefractive (PTR) glass is reported. The proposed scanner with no moving parts has a modular design with a wide angular scan range, accurate beam pointing, low scanner insertion loss, and two-dimensional beam scan capabilities. We present a complete analysis and design procedure for storing multiple tilted Bragg-grating structures in a single PTR glass volume (for normal incidence) in an optimal fashion. Because the scanner design is modular, many PTR glass volumes (each having multiple tilted Bragg-grating structures) can be stacked together, providing an efficient throughput with operations in both the visible and the infrared (IR) regions. A proof-of-concept experimental study is conducted with four Bragg gratings in independent PTR glass plates, and both visible and IR region scanner operations are demonstrated.

  6. High speed intravascular photoacoustic imaging with fast optical parametric oscillator laser at 1.7 μm

    PubMed Central

    Piao, Zhonglie; Ma, Teng; Li, Jiawen; Wiedmann, Maximilian T.; Huang, Shenghai; Yu, Mingyue; Kirk Shung, K.; Zhou, Qifa; Kim, Chang-Seok; Chen, Zhongping

    2015-01-01

    Intravascular photoacoustic imaging at 1.7 μm spectral band has shown promising capabilities for lipid-rich vulnerable atherosclerotic plaque detection. In this work, we report a high speed catheter-based integrated intravascular photoacoustic/intravascular ultrasound (IVPA/IVUS) imaging system with a 500 Hz optical parametric oscillator laser at 1725 nm. A lipid-mimicking phantom and atherosclerotic rabbit abdominal aorta were imaged at 1 frame per second, which is two orders of magnitude faster than previously reported in IVPA imaging with the same wavelength. Clear photoacoustic signals by the absorption of lipid rich deposition demonstrated the ability of the system for high speed vulnerable atherosclerotic plaques detection. PMID:26339072

  7. High speed intravascular photoacoustic imaging with fast optical parametric oscillator laser at 1.7 μm.

    PubMed

    Piao, Zhonglie; Ma, Teng; Li, Jiawen; Wiedmann, Maximilian T; Huang, Shenghai; Yu, Mingyue; Kirk Shung, K; Zhou, Qifa; Kim, Chang-Seok; Chen, Zhongping

    2015-08-24

    Intravascular photoacoustic imaging at 1.7 μm spectral band has shown promising capabilities for lipid-rich vulnerable atherosclerotic plaque detection. In this work, we report a high speed catheter-based integrated intravascular photoacoustic/intravascular ultrasound (IVPA/IVUS) imaging system with a 500 Hz optical parametric oscillator laser at 1725 nm. A lipid-mimicking phantom and atherosclerotic rabbit abdominal aorta were imaged at 1 frame per second, which is two orders of magnitude faster than previously reported in IVPA imaging with the same wavelength. Clear photoacoustic signals by the absorption of lipid rich deposition demonstrated the ability of the system for high speed vulnerable atherosclerotic plaques detection.

  8. High speed intravascular photoacoustic imaging with fast optical parametric oscillator laser at 1.7 μm

    NASA Astrophysics Data System (ADS)

    Piao, Zhonglie; Ma, Teng; Li, Jiawen; Wiedmann, Maximilian T.; Huang, Shenghai; Yu, Mingyue; Kirk Shung, K.; Zhou, Qifa; Kim, Chang-Seok; Chen, Zhongping

    2015-08-01

    Intravascular photoacoustic imaging at 1.7 μm spectral band has shown promising capabilities for lipid-rich vulnerable atherosclerotic plaque detection. In this work, we report a high speed catheter-based integrated intravascular photoacoustic/intravascular ultrasound (IVPA/IVUS) imaging system with a 500 Hz optical parametric oscillator laser at 1725 nm. A lipid-mimicking phantom and atherosclerotic rabbit abdominal aorta were imaged at 1 frame per second, which is two orders of magnitude faster than previously reported in IVPA imaging with the same wavelength. Clear photoacoustic signals by the absorption of lipid rich deposition demonstrated the ability of the system for high speed vulnerable atherosclerotic plaques detection.

  9. Noise performance of high-speed radio over fiber links employing vertical-cavity surface-emitting lasers

    NASA Astrophysics Data System (ADS)

    Ahmed, M.; Bakry, A.; Mahmoud, S. W. Z.

    2015-05-01

    This study investigates the intensity noise in high-speed vertical-cavity surface-emitting lasers (VCSELs) and its contribution to the noise performance of radio over fiber (RoF) links. We evaluate the sinusoidal modulation of VCSELs in terms of the second-order harmonic distortion (2HD) and third-order intermodulation distortion (IMD3) in additions to the relative intensity noise (RIN). The spurious-free dynamic range of the proposed VCSEL is estimated. The noise performance of the RoF link is assessed by the noise figure. The modulation characteristics of the VCSEL and the gain and noise factor (NF) of the fiber link are compared under conventional and high-speed modulations of VCSELs. Also, we present comparison of the NF between short (300 m) and relatively long (2 km) fibers.

  10. Fiber inline Michelson interferometer fabricated by one-step femtosecond laser micromachining for sensing applications

    NASA Astrophysics Data System (ADS)

    Yuan, Lei; Wu, Hongbin; Wang, Cong; Yu, Yingyu; Wang, Sumei; Xiao, Hai

    2013-12-01

    A fiber inline Michelson interferometer fiber optic sensor was presented for sensing applications, including high temperature performance and refractive index change. The sensor was fabricated using one-step femtosecond (fs) laser micromachining technique. A step structure at the tip of a single mode optical fiber was formed during the micromachining process. The device had a loss of 16 dB and an interference visibility exceeding 18 dB. The capability of this device for temperature sensing up to 1000 °C and refractive index sensing application in various concentrations of ethanol solution were all demonstrated.

  11. Acoustic comparison of Er,Cr:YSGG laser and dental high speed handpiece for primary anterior tooth preparation

    NASA Astrophysics Data System (ADS)

    Jorden, Monserrat; Chen, Jung-Wei; Easley, Elisabeth; Li, Yiming; Kurti, R. Steven

    The acoustics of a dental hard tissue laser (Er,Cr:YSGG laser, Waterlase MD, Biolase, USA) and a traditional dental high speed hand piece (Midwest®, Dentsply International, USA) were compared in vitro using a simple approach that can be easily adapted for in vivo studies. Thirty one extracted caries and restoration free primary anterior teeth were selected. These teeth were sectioned along a symmetry axis to give two identical halves for use in a split study. These halves were randomly assigned to either the laser (experimental) or the high speed (control) group. A miniature electret microphone was coupled to the sample using a polymer and used to collect the acoustic signal at the interface of the pulp chamber. This signal was captured periodically by a digitizing oscilloscope and multiple traces were stored for subsequent analysis. 2x1x1mm3 preparations were made according to manufacturers recommendations for the given method. Each cavity was prepared by the same clinician and calibration tests were performed to ensure consistency. The measurements indicated that the peak acoustic pressures as well as cumulative acoustic effects (due to duty cycle) were significantly higher (P<0.001, T-test) with the dental hand piece than with the dental laser. Our study suggests the need for further investigations into the neurological implications of acoustic effects in dental patient care such as pain studies.

  12. Visualization of hair follicles using high-speed optical coherence tomography based on a Fourier domain mode locking laser

    NASA Astrophysics Data System (ADS)

    Tsai, M.-T.; Chang, F.-Y.

    2012-04-01

    In this study, a swept-source optical coherence tomography (SS-OCT) system with a Fourier domain mode locking (FDML) laser is proposed for a dermatology study. The homemade FDML laser is one kind of frequency-sweeping light source, which can provide output power of >20 mW and an output spectrum of 65 nm in bandwidth centered at 1300 nm, enabling imaging with an axial resolution of 12 μm in the OCT system. To eliminate the forward scans from the laser output and insert the delayed backward scans, a Mach-Zehnder configuration is implemented. Compared with conventional frequency-sweeping light sources, the FDML laser can achieve much higher scan rates, as high as ˜240 kHz, which can provide a three-dimensional imaging rate of 4 volumes/s. Furthermore, the proposed high-speed SS-OCT system can provide three-dimensional (3D) images with reduced motion artifacts. Finally, a high-speed SS-OCT system is used to visualize hair follicles, demonstrating the potential of this technology as a tool for noninvasive diagnosis of alopecia.

  13. Metallic nanoparticles grown in the core of femtosecond laser micromachined waveguides

    SciTech Connect

    Almeida, J. M. P.; Ferreira, P. H. D.; Mendonça, C. R.; Manzani, D.; Napoli, M.; Ribeiro, S. J. L.

    2014-05-21

    3D-waveguides containing silver nanoparticles have been fabricated in tungsten lead–pyrophosphate glass by femtosecond laser micromachining. Nucleation and growth of nanoparticles occur in a single step process when high repetition rate laser (MHz) is employed, while an additional annealing is required for the irradiation using kHz laser system. The presence of nanoparticles locally changes the refractive index, and, therefore, the elliptical structures produced by direct laser writing were able to guide light. By increasing the pulse energy applied during the micromachining, the waveguide size increased from 2 to 30 μm, while their propagation loss decrease from 1.4 to 0.5 dB/mm at 632.8 nm.

  14. Micromachining of polyurethane (PU) polymer using a KrF excimer laser (248 nm)

    NASA Astrophysics Data System (ADS)

    Singh, Sarabpreet; Sharma, Sunil

    2014-12-01

    Polyurethane (PU) polymer, due to its biocompatibility, weather resistance, and favorable physical properties, finds a number of applications in medical implants, protective coatings, and as a prototype material for structural components in MEMS devices. An excimer laser (wavelength = 248 nm, FWHM = 25 ns) is employed for micromachining of polyurethane (PU) polymer. For air environment, the ablation rate is 0.18 μm/pulse and for underwater environment, the ablation rate is 0.07 μm/pulse (with underwater ablation threshold as 0.10 J/cm2), which concluded low taper angles (∼32°) for in air as compared to high taper angles (∼65°) with underwater micromachining. The experimental results for air and under water micromachining demonstrate ablation process as a combination of photo-thermal and photo-chemical mechanism.

  15. High-throughput machining using a high-average power ultrashort pulse laser and high-speed polygon scanner

    NASA Astrophysics Data System (ADS)

    Schille, Joerg; Schneider, Lutz; Streek, André; Kloetzer, Sascha; Loeschner, Udo

    2016-09-01

    High-throughput ultrashort pulse laser machining is investigated on various industrial grade metals (aluminum, copper, and stainless steel) and Al2O3 ceramic at unprecedented processing speeds. This is achieved by using a high-average power picosecond laser in conjunction with a unique, in-house developed polygon mirror-based biaxial scanning system. Therefore, different concepts of polygon scanners are engineered and tested to find the best architecture for high-speed and precision laser beam scanning. In order to identify the optimum conditions for efficient processing when using high-average laser powers, the depths of cavities made in the samples by varying the processing parameter settings are analyzed and, from the results obtained, the characteristic removal values are specified. For overlapping pulses of optimum fluence, the removal rate is as high as 27.8 mm3/min for aluminum, 21.4 mm3/min for copper, 15.3 mm3/min for stainless steel, and 129.1 mm3/min for Al2O3, when a laser beam of 187 W average laser powers irradiates. On stainless steel, it is demonstrated that the removal rate increases to 23.3 mm3/min when the laser beam is very fast moving. This is thanks to the low pulse overlap as achieved with 800 m/s beam deflection speed; thus, laser beam shielding can be avoided even when irradiating high-repetitive 20-MHz pulses.

  16. 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

  17. Experimental and theoretical study of the laser micro-machining of glass using high-repetition-rate ultrafast laser

    NASA Astrophysics Data System (ADS)

    Yashkir, Yuri; Liu, Qiang

    2006-04-01

    We present a systematic study of the ultrafast laser micro-machining of glass using a Ti:Spp laser with moderate pulse energy (<5 μJ) at a high repetition rate (50 kHz). Optimal conditions were identified for high resolution surface laser etching, and via drilling. Several practical applications were developed: glass templates for micro fluid diffraction devices, phase gratings for excimer laser projection techniques, micro fluid vertical channel-connectors, etc. It is demonstrated that the interaction of ultrafast laser pulses with glass combines several different processes (direct ablation, explosive material ejection, and thermal material modification). A dynamic numerical model was developed for this process. It was successfully used for modelling of laser micro-machining with arbitrary 3D translations of the target.

  18. Fiber laser micromachining of magnesium alloy tubes for biocompatible and biodegradable cardiovascular stents

    NASA Astrophysics Data System (ADS)

    Demir, Ali Gökhan; Previtali, Barbara; Colombo, Daniele; Ge, Qiang; Vedani, Maurizio; Petrini, Lorenza; Wu, Wei; Biffi, Carlo Alberto

    2012-02-01

    Magnesium alloys constitute an attractive solution for cardiovascular stent applications due to their intrinsic properties of biocompatibility and relatively low corrosion resistance in human-body fluids, which results in as a less intrusive treatment. Laser micromachining is the conventional process used to cut the stent mesh, which plays the key role for the accurate reproduction of the mesh design and the surface quality of the produced stent that are important factors in ensuring the mechanical and corrosion resistance properties of such a kind of devices. Traditionally continuous or pulsed laser systems working in microsecond pulse regime are employed for stent manufacturing. Pulsed fiber lasers on the other hand, are a relatively new solution which could balance productivity and quality aspects with shorter ns pulse durations and pulse energies in the order of mJ. This work reports the study of laser micromachining and of AZ31 magnesium alloy for the manufacturing of cardiovascular stents with a novel mesh design. A pulsed active fiber laser system operating in nanosecond pulse regime was employed for the micromachining. Laser parameters were studied for tubular cutting on a common stent material, AISI 316L tubes with 2 mm in diameter and 0.2 mm in thickness and on AZ31 tubes with 2.5 mm in diameter and 0.2 in thickness. In both cases process parameters conditions were examined for reactive and inert gas cutting solutions and the final stent quality is compared.

  19. High-speed visualization and radiated pressure measurement of a laser-induced gas bubble in glycerin-water solutions

    NASA Astrophysics Data System (ADS)

    Nakajima, Takehiro; Kondo, Tomoki; Ando, Keita

    2016-11-01

    We study the dynamics of a spherical gaseous bubble created by focusing a nanosecond laser pulse at 532 nm into a large volume of glycerin-water solutions. Free oscillation of the bubble and shock wave emission from the bubble dynamics are recorded by a high-speed camera together with a pulse laser stroboscope; concurrently, pressure radiated from the oscillating bubble is measured by a hydrophone. The bubble achieves a mechanical equilibrium after free oscillation is damped out; the equilibrium state stays for a while, unlike vapor bubbles. We speculate that the bubble content is mainly gases originally dissolved in the liquid (i.e., air). The bubble dynamics we observed are compared to Rayleigh-Plesset-type calculations that account for diffusive effects; the (unknown) initial pressure just after laser focusing is tuned to obtain agreement between the experiment and the calculation. Moreover, viscous effects on the shock propagation are examined with the aid of compressible Navier-Stokes simulation.

  20. High-speed dispersion-tuned wavelength-swept fiber laser using a reflective SOA and a chirped FBG.

    PubMed

    Takubo, Yuya; Yamashita, Shinji

    2013-02-25

    We present a high-speed wavelength-swept fiber laser based on a dispersion tuning method using a reflective semiconductor optical amplifier (RSOA) and a chirped fiber Bragg grating (CFBG). By using these devices, the cavity length can be shortened drastically. The short cavity improves the laser performance at high sweep rates over 200 kHz. We achieve a sweep range of 60 nm and an output power of 8.4 mW at 100 kHz sweep. We applied the dispersion-tuned fiber laser to the swept-source OCT system and successfully obtained OCT images of an adhesive tape at up to 250 kHz sweep rate.

  1. Three-dimensional optical reconstruction of vocal fold kinematics using high-speed video with a laser projection system

    PubMed Central

    Luegmair, Georg; Mehta, Daryush D.; Kobler, James B.; Döllinger, Michael

    2015-01-01

    Vocal fold kinematics and its interaction with aerodynamic characteristics play a primary role in acoustic sound production of the human voice. Investigating the temporal details of these kinematics using high-speed videoendoscopic imaging techniques has proven challenging in part due to the limitations of quantifying complex vocal fold vibratory behavior using only two spatial dimensions. Thus, we propose an optical method of reconstructing the superior vocal fold surface in three spatial dimensions using a high-speed video camera and laser projection system. Using stereo-triangulation principles, we extend the camera-laser projector method and present an efficient image processing workflow to generate the three-dimensional vocal fold surfaces during phonation captured at 4000 frames per second. Initial results are provided for airflow-driven vibration of an ex vivo vocal fold model in which at least 75% of visible laser points contributed to the reconstructed surface. The method captures the vertical motion of the vocal folds at a high accuracy to allow for the computation of three-dimensional mucosal wave features such as vibratory amplitude, velocity, and asymmetry. PMID:26087485

  2. High-speed scanning of critical structures in aviation using coordinate measurement machine and the laser ultrasonic.

    PubMed

    Swornowski, Pawel J

    2012-01-01

    Aviation is one of the know-how spheres containing a great deal of responsible sub-assemblies, in this case landing gear. The necessity for reducing production cycle times while achieving better quality compels metrologists to look for new and improved ways to perform inspection of critical structures. This article describes the ability to determine the shape deviation and location of defects in landing gear using coordinate measuring machines and laser ultrasonic with high-speed scanning. A nondestructive test is the basis for monitoring microcrack and corrosion propagation in the context of a damage-tolerant design approach. This article presents an overview of the basics and of the various metrological aspects of coordinate measurement and a nondestructive testing method in terms of high-speed scanning. The new test method (laser ultrasonic) promises to produce the necessary increase in inspection quality, but this is limited by the wide range of materials, geometries, and structure aeronautic parts used. A technique combining laser ultrasonic and F-SAFT (Fourier-Synthetic Aperture Focusing Technique) processing has been proposed for the detection of small defects buried in landing gear. The experimental results of landing gear inspection are also presented. © Wiley Periodicals, Inc.

  3. Three-Dimensional Optical Reconstruction of Vocal Fold Kinematics Using High-Speed Video With a Laser Projection System.

    PubMed

    Luegmair, Georg; Mehta, Daryush D; Kobler, James B; Döllinger, Michael

    2015-12-01

    Vocal fold kinematics and its interaction with aerodynamic characteristics play a primary role in acoustic sound production of the human voice. Investigating the temporal details of these kinematics using high-speed videoendoscopic imaging techniques has proven challenging in part due to the limitations of quantifying complex vocal fold vibratory behavior using only two spatial dimensions. Thus, we propose an optical method of reconstructing the superior vocal fold surface in three spatial dimensions using a high-speed video camera and laser projection system. Using stereo-triangulation principles, we extend the camera-laser projector method and present an efficient image processing workflow to generate the three-dimensional vocal fold surfaces during phonation captured at 4000 frames per second. Initial results are provided for airflow-driven vibration of an ex vivo vocal fold model in which at least 75% of visible laser points contributed to the reconstructed surface. The method captures the vertical motion of the vocal folds at a high accuracy to allow for the computation of three-dimensional mucosal wave features such as vibratory amplitude, velocity, and asymmetry.

  4. Performance characterization of low-cost, high-speed, portable pulsed laser diode photoacoustic tomography (PLD-PAT) system.

    PubMed

    Upputuri, Paul Kumar; Pramanik, Manojit

    2015-10-01

    Photoacoustic tomography systems that uses Q-switched Nd:YAG/OPO pulsed lasers are expensive, bulky, and hence limits its use in clinical applications. The low pulse repetition rate of these lasers makes it unsuitable for real-time imaging when used with single-element ultrasound detector. In this work, we present a pulsed laser diode photoacoustic tomography (PLD-PAT) system that integrates a compact PLD inside a single-detector circular scanning geometry. We compared its performance against the traditional Nd:YAG/OPO based PAT system in terms of imaging depth, resolution, imaging time etc. The PLD provides near-infrared pulses at ~803 nm wavelength with pulse energy ~1.4 mJ/pulse at 7 kHz repetition rate. The PLD-PAT system is capable of providing 2D image in scan time as small as 3 sec with a signal-to-noise ratio ~30. High-speed and deep-tissue imaging is demonstrated on phantoms and biological samples. The PLD-PAT system is inexpensive, portable, allows high-speed PAT imaging, and its performance is as good as traditional expensive OPO based PAT system. Therefore, it holds promises for future translational biomedical imaging applications.

  5. High-speed, three-dimensional tomographic laser-induced incandescence imaging of soot volume fraction in turbulent flames.

    PubMed

    Meyer, Terrence R; Halls, Benjamin R; Jiang, Naibo; Slipchenko, Mikhail N; Roy, Sukesh; Gord, James R

    2016-12-26

    High-speed, laser-based tomographic imaging of the three-dimensional time evolution of soot volume fraction in turbulent jet diffusion flames is demonstrated to be feasible at rates of 10 kHz or higher. The fundamental output of a burst-mode Nd:YAG laser with 1 J/pulse is utilized for volumetric impulsive heating of soot particles with a laser fluence of 0.1 J/cm2, enabling signal-to-noise ratios of ~100:1 in images of the resulting incandescence. The three-dimensional morphology of the soot distribution is captured with a spatial resolution of <1.5 mm using as few as four viewing angles, with convergence of the soot volume fraction to within ~95% occurring with seven or more viewing angles. Uniqueness of the solution is demonstrated using two sets of eight images captured at the same time instant, with agreement to >90% in peak values between the two sets. These data establish parameters for successful high-speed, three-dimensional imaging of the soot volume fraction within highly transient combustion environments.

  6. High-speed laser-induced fluorescence and spark plug absorption sensor diagnostics for mixing and combustion studies in engines.

    PubMed

    Cundy, Michael; Schucht, Torsten; Thiele, Olaf; Sick, Volker

    2009-02-01

    Simultaneous high-speed in-cylinder measurements of laser-induced fluorescence of biacetyl as a fuel tracer and mid-infrared broadband absorption of fuel and combustion products (water and carbon dioxide) using a spark plug probe are compared in an optical engine. The study addresses uncertainties and the applicability of absorption measurements at a location slightly offset to the spark plug when information about mixing at the spark plug is desired. Absorbance profiles reflect important engine operation events, such as valve opening and closing, mixing, combustion, and outgassing from crevices.

  7. High speed three-dimensional laser scanner with real time processing

    NASA Technical Reports Server (NTRS)

    Lavelle, Joseph P. (Inventor); Schuet, Stefan R. (Inventor)

    2008-01-01

    A laser scanner computes a range from a laser line to an imaging sensor. The laser line illuminates a detail within an area covered by the imaging sensor, the area having a first dimension and a second dimension. The detail has a dimension perpendicular to the area. A traverse moves a laser emitter coupled to the imaging sensor, at a height above the area. The laser emitter is positioned at an offset along the scan direction with respect to the imaging sensor, and is oriented at a depression angle with respect to the area. The laser emitter projects the laser line along the second dimension of the area at a position where a image frame is acquired. The imaging sensor is sensitive to laser reflections from the detail produced by the laser line. The imaging sensor images the laser reflections from the detail to generate the image frame. A computer having a pipeline structure is connected to the imaging sensor for reception of the image frame, and for computing the range to the detail using height, depression angle and/or offset. The computer displays the range to the area and detail thereon covered by the image frame.

  8. Micromachining of microchannel on the polycarbonate substrate with CO 2 laser direct-writing ablation

    NASA Astrophysics Data System (ADS)

    Qi, Heng; Chen, Tao; Yao, Liying; Zuo, Tiechuan

    2009-05-01

    Low-power CO 2 laser direct-writing ablation was used to micromachine a microchannel on the polycarbonate substrate in this work. The influence of the process parameters (the laser power, the moving velocity of the laser beam and the scanning times) on the micromachining quality (the depth, the width and their aspect ratio) of the microchannel was experimentally studied. The depth and width of microchannel both increase with the increase of the laser power and the decrease of the moving velocity of the laser beam. When higher laser power and slower moving velocity were used, the polycarbonate surface bore more heat irradiated from the CO 2 laser for longer time which results in the formation of deeper and wider molten pool, hence the ability to fabricate bigger microchannel. Because of the effect of the laser power on the depth and width of microchannels, higher aspect (depth/width) ratio could be achieved using slower moving velocity and higher laser power, and it would reach a steady state when the laser power increases to 9.0 W possibly caused by the effect of laser power on the different directions of microchannel. The polycarbonate-polycarbonate chip was bonded with hot-press bonding technique.

  9. High-speed laser modulation beyond the relaxation resonance frequency limit.

    PubMed

    Sacher, Wesley D; Zhang, Eric J; Kruger, Brett A; Poon, Joyce K S

    2010-03-29

    We propose and show that for coupling modulated lasers (CMLs), in which the output coupler is modulated rather than the pump rate, the conventional relaxation resonance frequency limit to the laser modulation bandwidth can be circumvented. The modulation response is limited only by the coupler. Although CMLs are best suited to microcavities, as a proof-of-principle, a coupling-modulated erbium-doped fiber laser is modulated at 1 Gb/s, over 10000 times its relaxation resonance frequency.

  10. Nd:YAG laser micromachining of SiC precision structures for MEMS

    NASA Astrophysics Data System (ADS)

    Kreutz, Ernst-Wolfgang; Weichenhain, Ruth; Horn, Alexander

    2001-04-01

    Micromachining of SiC with 1(omega) , 2(omega) , 3(omega) -Nd:YAG laser radiation with pulse durations in the ps to ns regime is performed in various processing gas atmospheres as a function of processing variables showing the influence of the heat and pressure load onto the precision of geometric structures generated. The physical and chemical processes involved in micromachining with laser radiation are characterized by a machine vision system and the produced structures are analyzed by profilometry, optical and electron microscopy as well as X- photoelectron spectroscopy. 3D microstructures are produced by scanning and turning the laser beam onto the material surface, width of structures < 100 micrometers and surface roughness < 2 micrometers , for example, require an overlap < 0.8 independent of the type of processing gas under investigation.

  11. Optical characteristics of femtosecond laser micromachined periodic structures in Si <100>.

    PubMed

    Elbandrawy, Mohamed; Gupta, Mool C

    2006-09-20

    A frequency doubled Ti:sapphire laser of 400 nm wavelength, 160 fs pulse width, and 1 kHz repetition rate, combined with a high resolution computer-controlled X-Y stage, was used to direct write periodic structures on Si <100>. Laser pulses of approximately 130 nJ energy were focused using an objective lens of 0.65 NA. Laser micromachining yielded lines of 700 nm width and ablation depths of 600 nm. One- and two-dimensional periodic structures of 5 and 5x5 microm spacing were fabricated, and the structures were characterized by using optical and atomic force microscopy. The light diffraction characteristics of the periodic 1D and 2D patterns were examined. The diffraction properties of the 1D structures were highly dependent upon the light polarization orientation with respect to the micromachining direction.

  12. The implementation of the combined high-speed laser scanning for SRS-lidar

    NASA Astrophysics Data System (ADS)

    Iakovlev, Alexey; Zhevlakov, Aleksandr; Elizarov, Valentin; Grishkanich, Aleksandr; Kascheev, Sergey V.; Mak, Andrey; Smirnov, Leonid

    2017-02-01

    We discuss implementation of the combined node scanning SRS lidar system for high-speed and high spatial resolution (about 3 cm) scanning in wide and narrow angle at a distance of 50-100 m. Narrowband scanning is performed by the deflector moving along a spiral path. Rotating angle wedges of the deflector deviate a beam by an angle of +/- 50. This design constitutes an "optical reduction" wedge between the steering angle and the deflection angle of the optical axis and allows 15 ' positioning accuracy. overview of the entire study area for no more than 1 ms at a frequency of rotation of each of the wedges of 50-200 Hz. Unambiguous definition of the geographical coordinates of the probed object is achieved by using high-precision GPS-module and the Vincenty's algorithms. It allows to build a 3D spatial distribution of concentrations of air pollutants.

  13. Characterization of calculus migration during Ho:YAG laser lithotripsy by high speed camera using suspended pendulum method

    NASA Astrophysics Data System (ADS)

    Zhang, Jian James; Rajabhandharaks, Danop; Xuan, Jason Rongwei; Chia, Ray W. J.; Hasenberg, Tom

    2014-03-01

    Calculus migration is a common problem during ureteroscopic laser lithotripsy procedure to treat urolithiasis. A conventional experimental method to characterize calculus migration utilized a hosting container (e.g. a "V" grove or a test tube). These methods, however, demonstrated large variation and poor detectability, possibly attributing to friction between the calculus and the container on which the calculus was situated. In this study, calculus migration was investigated using a pendulum model suspended under water to eliminate the aforementioned friction. A high speed camera was used to study the movement of the calculus which covered zero order (displacement), 1st order (speed) and 2nd order (acceleration). A commercialized, pulsed Ho:YAG laser at 2.1 um, 365-um core fiber, and calculus phantom (Plaster of Paris, 10×10×10mm cube) were utilized to mimic laser lithotripsy procedure. The phantom was hung on a stainless steel bar and irradiated by the laser at 0.5, 1.0 and 1.5J energy per pulse at 10Hz for 1 second (i.e., 5, 10, and 15W). Movement of the phantom was recorded by a high-speed camera with a frame rate of 10,000 FPS. Maximum displacement was 1.25+/-0.10, 3.01+/-0.52, and 4.37+/-0.58 mm for 0.5, 1, and 1.5J energy per pulse, respectively. Using the same laser power, the conventional method showed <0.5 mm total displacement. When reducing the phantom size to 5×5×5mm (1/8 in volume), the displacement was very inconsistent. The results suggested that using the pendulum model to eliminate the friction improved sensitivity and repeatability of the experiment. Detailed investigation on calculus movement and other causes of experimental variation will be conducted as a future study.

  14. High-speed laser anemometer system for intrarotor flow mapping in turbomachinery

    NASA Technical Reports Server (NTRS)

    Powell, J. A.; Strazisar, A. J.; Seasholtz, R. G.

    1982-01-01

    A fringe-type laser anemometer with innovative features is described. The innovative features include: (1) rapid, efficient data acquisition processes, (2) detailed graphic display of data being accumulated, and (3) input laser-beam positioning that allows greater optical access to the intrarotor region. Results are presented that demonstrate the anemometer's capability in flow mapping within a transonic axial-flow compressor rotor.

  15. High-speed laser anemometer system for intrarotor flow mapping in turbomachinery

    NASA Astrophysics Data System (ADS)

    Powell, J. A.; Strazisar, A. J.; Seasholtz, R. G.

    1982-02-01

    A fringe-type laser anemometer with innovative features is described. The innovative features include: (1) rapid, efficient data acquisition processes, (2) detailed graphic display of data being accumulated, and (3) input laser-beam positioning that allows greater optical access to the intrarotor region. Results are presented that demonstrate the anemometer's capability in flow mapping within a transonic axial-flow compressor rotor.

  16. Lithium iron phosphate battery electrode integrity following high speed pulsed laser cutting

    NASA Astrophysics Data System (ADS)

    Lutey, Adrian H. A.; Fiorini, Maurizio; Fortunato, Alessandro; Carmignato, Simone

    2015-05-01

    Laser exposures are performed on lithium iron phosphate battery electrodes at with process parameters based on those leading to the smallest heat affected zone for low power laser exposure at . Scanning electron microscopy and Raman analysis are performed along the resulting cut edges to characterize macroscopic, chemical and microstructural changes resulting from laser exposure. The increase in velocity with respect to previous studies is found to limit macroscopic changes to areas directly exposed to the laser beam and greatly suppress or completely eliminate microstructural and chemical changes resulting from thermal conduction effects in the metallic conductor layers. These results confirm laser technology as a viable, more flexible solution to mechanical blanking devices for the cutting of lithium iron phosphate battery electrode films.

  17. High speed, high strength microwelding of Si/glass using ps-laser pulses.

    PubMed

    Miyamoto, Isamu; Okamoto, Yasuhiro; Hansen, Assi; Vihinen, Joma; Amberla, Tiina; Kangastupa, Jarno

    2015-02-09

    A novel microwelding procedure to join Si-to-glass using ps-laser pulses with high repetition rates is presented. The procedure provides weld joint with mechanical strength as high as 85 MPa and 45 MPa in sample pairs of Si/aluminosilicate (Si/SW-Y) and Si/borosilicate (Si/Borofloat 33), respectively, which are higher than anodic bonding, at high spatial resolution (< 20 µm) and very high throughput without pre- and post-heating. Laser-matter interaction analysis indicates that excellent weld joint of Si/glass is obtained by avoiding violent evaporation of Si substrate using ps-laser pulses. Laser welded Si/glass samples can be singulated along the weld lines by standard blade dicer without defects, demonstrating welding by ps-laser pulses is applicable to wafer-level packaging.

  18. High-speed ultrashort pulse fiber ring laser using charcoal nanoparticles.

    PubMed

    Li, Wenbo; Hu, Hongyu; Zhang, Xiang; Zhao, Shuai; Fu, Kan; Dutta, Niloy K

    2016-03-20

    A mode-locked erbium-doped fiber ring laser that is easy to set up is proposed and experimentally demonstrated to generate a high-repetition-rate optical pulse train with an ultrashort pulse width. The laser combines a rational harmonic mode-locking technique and charcoal nanoparticles as saturable absorbers. Compared to a solely active mode-locking scheme, the scheme with charcoal nanoparticles can remove the supermodes and narrow the pulse width by a factor of 0.57 at a repetition rate of 20 GHz. Numerical simulation of the laser performance is also provided, which shows good agreement with the experimental results.

  19. High-speed measurements of steel-plate deformations during laser surface processing.

    PubMed

    Jezersek, Matija; Gruden, Valter; Mozina, Janez

    2004-10-04

    In this paper we present a novel approach to monitoring the deformations of a steel plate's surface during various types of laser processing, e.g., engraving, marking, cutting, bending, and welding. The measuring system is based on a laser triangulation principle, where the laser projector generates multiple lines simultaneously. This enables us to measure the shape of the surface with a high sampling rate (80 Hz with our camera) and high accuracy (+/-7 microm). The measurements of steel-plate deformations for plates of different thickness and with different illumination patterns are presented graphically and in an animation.

  20. Femtosecond-pulsed laser micromachining of a 4H SiC wafer for MEMS pressure sensor diaphragms and via holes

    NASA Astrophysics Data System (ADS)

    Dong, Yuanyuan; Nair, Rajeev; Molian, Raathai; Molian, Pal

    2008-03-01

    The challenging issues in conventional microfabrication of SiC pressure sensor diaphragms from bulk wafers are low etch rates, thicker (>40 µm) diaphragms, low spatial resolutions, rough surfaces and substantial contamination. In via hole drilling of SiC, the critical concern is the low drilling speed (nm per minute). In this work, femtosecond (fs)-pulsed laser ablation was conducted to overcome some of these deficiencies. Circular diaphragms (0.5 to 1 mm) by trepanning mode and via holes (30-50 µm) by percussion drilling mode were micromachined in 250 µm thick 4H-SiC single crystals using an 800 nm wavelength, 120 fs, 1 mJ Ti:sapphire laser. Pulse energy, number of pulses and scan rate were varied to obtain a high etch rate and high quality features. Results showed that the etch rates are 2-10 µm per pulse, diaphragm thicknesses are 20-200 µm, surface roughness is 1-2 µm Ra and via hole drilling speeds are up to 25 µm per second. The etch depth control was well within ± 1%. High aspect ratio features with excellent spatial resolutions were obtained due to the absence of thermal damages such as a recast layer and contamination. Thus, femtosecond-pulsed laser ablation by virtue of its unique characteristics such as multiphoton ionization and the absence of lattice heating offers high speed, precision and accuracy in micromachining 4H-SiC wafers.

  1. Microstructure and its effect on toughness and wear resistance of laser surface melted and post heat treated high speed steel

    NASA Astrophysics Data System (ADS)

    Åhman, Leif

    1984-10-01

    High speed steel hacksaw blade blanks were laser surface melted and rapidly solidified along one edge. The laser melting resulted in complete carbide dissolution. By subsequent machining and heat treatments saw teeth were manufactured with a refined internal structure of the edges and corners. The structure was fully martensitic with a uniform and dense dispersion of small primary carbides. Sawing tests in quenched and tempered steel showed that blade life was somewhat improved, as compared to conventionally heat treated blades. The increased wear resistance is believed to be due to improved toughness along with high hardness caused by the refined carbide structure. Sawing tests in austenitic stainless steel did not give any significant improvement in performance. The effect of the altered microstructure on performance is likely to be more or less pronounced depending on application, tool and work material.

  2. Femtosecond two-photon laser-induced fluorescence of krypton for high-speed flow imaging.

    PubMed

    Wang, Yejun; Capps, Cade; Kulatilaka, Waruna D

    2017-02-15

    Ultrashort-pulse (femtosecond-duration) two-photon laser-induced fluorescence (fs-TPLIF) of an inert gas tracer krypton (Kr) is investigated. A detailed spectroscopic study of fluorescence channels followed by the 5p'←←4p excitation of Kr at 204.1 nm is reported. The experimental line positions in the 750-840 nm emission region agree well with the NIST Atomic Spectra Database. The present work provides an accurate listing of relative line strengths in this spectral region. In the range of laser pulse energies investigated, a quadratic dependence was observed between the Kr-TPLIF signal and the laser pulse energy. The single-laser-shot 2D TPLIF images recorded in an unsteady jet demonstrate the potential of using fs excitation at 204.1 nm for mixing and flow diagnostic studies using Kr as an inert gas tracer.

  3. Nano-strip grating lines self-organized by a high speed scanning CW laser

    NASA Astrophysics Data System (ADS)

    Kaneko, Satoru; Ito, Takeshi; Akiyama, Kensuke; Yasui, Manabu; Kato, Chihiro; Tanaka, Satomi; Hirabayashi, Yasuo; Mastuno, Akira; Nire, Takashi; Funakubo, Hiroshi; Yoshimoto, Mamoru

    2011-04-01

    After a laser annealing experiment on Si wafer, we found an asymmetric sheet resistance on the surface of the wafer. Periodic nano-strip grating lines (nano-SGLs) were self-organized along the trace of one-time scanning of the continuous wave (CW) laser. Depending on laser power, the nano-trench formed with a period ranging from 500 to 800 nm with a flat trough between trench structures. This simple method of combining the scanning laser with high scanning speed of 300 m min - 1 promises a large area of nanostructure fabrication with a high output. As a demonstration of the versatile method, concentric circles were drawn on silicon substrate rotated by a personal computer (PC) cooling fan. Even with such a simple system, the nano-SGL showed iridescence from the concentric circles.

  4. Laser Doppler phase shifting using a high-speed digital micromirror device

    NASA Astrophysics Data System (ADS)

    Kuo, D.; Sharpe, J. P.

    2015-03-01

    Here we demonstrate the use of a binary spatial light modulator (Texas Instruments Digital Micromirror Device) to impart a phase shift to the beams of a laser Doppler velocimeter. Advantages of this approach to laser Doppler phase shifting include low cost, low power consumption, a precisely known phase-stepping frequency and the capability of working with a broad range of optical wavelengths. In the implementation shown here velocities of order 1 cm/s are measured.

  5. High-speed photography during laser-based gall bladder stone lithotripsy

    NASA Astrophysics Data System (ADS)

    Kokaj, Jahja O.

    2001-04-01

    Shadowgraphy of gall bladder stone, which is held by a basket and immersed in a civete is performed. The exposure time is determined by the time of a N-Dye laser pulse used as a lightening source for photography. The shadowgram is projected in the objective of a camera which is connected to a microscope. The light coming from the laser, illuminates the civete collecting optical information of the stone and physical phenomena appearing above the stone. On top of the stone a tip of optical fiber is fixed, which is used for transmitting Ho:Yag laser power to the stone. Using a computer and time delay the laser pulses used for destruction and illumination are synchronized. Since the N-Dye laser pulse is pico-second range and the Ho:Yag laser pulse is in the range of micro-second, many image frames are obtained within the time of one pulse applied during the destruction. It is known that in the process of stone destruction several phenomena like plume, plasma, shock wave and bubble formation take place. However, the physical mechanism of the stone destruction is not yet completely understood. From the obtained results the above phenomena are studied which gives new information and clue for understanding some of the mentioned phenomena. The laser power which is guided by an optical fiber into the gall bladder or kidney of the human body can damage the living tissue and cause some serious health problems. For this reason the fiber needs to be oriented properly during the action of the laser power.

  6. High-speed deposition of titanium carbide coatings by laser-assisted metal–organic CVD

    SciTech Connect

    Gong, Yansheng; Tu, Rong; Goto, Takashi

    2013-08-01

    Graphical abstract: - Highlights: • A semiconductor laser was first used to prepare wide-area LCVD-TiC{sub x} coatings. • The effect of laser power for the deposition of TiC{sub x} coatings was discussed. • TiC{sub x} coatings showed a columnar cross section and a dense surface texture. • TiC{sub x} coatings had a 1–4 order lower laser density than those of previous reports. • This study gives the possibility of LCVD applying on the preparation of TiC{sub x} coating. - Abstract: A semiconductor laser-assisted chemical vapor deposition (LCVD) of titanium carbide (TiC{sub x}) coatings on Al{sub 2}O{sub 3} substrate using tetrakis (diethylamido) titanium (TDEAT) and C{sub 2}H{sub 2} as source materials were investigated. The influences of laser power (P{sub L}) and pre-heating temperature (T{sub pre}) on the microstructure and deposition rate of TiC{sub x} coatings were examined. Single phase of TiC{sub x} coatings were obtained at P{sub L} = 100–200 W. TiC{sub x} coatings had a cauliflower-like surface and columnar cross section. TiC{sub x} coatings in the present study had the highest R{sub dep} (54 μm/h) at a relative low T{sub dep} than those of conventional CVD-TiC{sub x} coatings. The highest volume deposition rate (V{sub dep}) of TiC{sub x} coatings was about 4.7 × 10{sup −12} m{sup 3} s{sup −1}, which had 3–10{sup 5} times larger deposition area and 1–4 order lower laser density than those of previous LCVD using CO{sub 2}, Nd:YAG and argon ion laser.

  7. Can fiber laser improve high speed multi-pulse drilling of aeronautic alloy?

    NASA Astrophysics Data System (ADS)

    Nguyen, M.; Loumena, C.; Bussière, A.; Kling, R.; Delor, C.; Freysz, E.

    2016-03-01

    Processing of helicopter engines faster, better and more reliably is the triptych which binds LOMA, ALPhANOV and TURBOMECA. In current production machines, flash lamp pumped lasers are employed to drill thousands of cooling holes with specific geometries and diameters to ensure a homogeneous air flow over the surface. However we aim to enhance the production process. Therefore, the three partners started an initiative to identify and overcome the shortcomings of the current process, where the laser source is a key element for improvement. In this paper, we report on the latest developments in multi-pulse drilling using an IPG fiber laser. The latter delivers, at a tunable repetition rate (from single shot up to 2 kHz), laser pulses whose width and peak power are adjustable in between 0.2 - 10 ms and 0 - 12 kW respectively. We have focused our work on drilling of thick sheets of metal alloys with different geometries and different processing strategies. We will show that using such laser system it is possible to decrease the processing time while limiting the heat affected zones and collateral effects. Finally, the impact of the different physical processes in play during the drilling on the geometry of the holes will be discussed.

  8. Femtosecond laser micromachining of compound parabolic concentrator fiber tipped glucose sensors

    NASA Astrophysics Data System (ADS)

    Hassan, Hafeez Ul; Lacraz, Amédée; Kalli, Kyriacos; Bang, Ole

    2017-03-01

    We report on highly accurate femtosecond (fs) laser micromachining of a compound parabolic concentrator (CPC) fiber tip on a polymer optical fiber (POF). The accuracy is reflected in an unprecedented correspondence between the numerically predicted and experimentally found improvement in fluorescence pickup efficiency of a Förster resonance energy transfer-based POF glucose sensor. A Zemax model of the CPC-tipped sensor predicts an optimal improvement of a factor of 3.96 compared to the sensor with a plane-cut fiber tip. The fs laser micromachined CPC tip showed an increase of a factor of 3.5, which is only 11.6% from the predicted value. Earlier state-of-the-art fabrication of the CPC-shaped tip by fiber tapering was of so poor quality that the actual improvement was 43% lower than the predicted improvement of the ideal CPC shape.

  9. Micromachining of bulk glass with bursts of femtosecond laser pulses at variable repetition rates.

    PubMed

    Gattass, Rafael R; Cerami, Loren R; Mazur, Eric

    2006-06-12

    Oscillator-only femtosecond laser micromachining enables the manufacturing of integrated optical components with circular transverse profiles in transparent materials. The circular profile is due to diffusion of heat accumulating at the focus. We control the heat diffusion by focusing bursts of femtosecond laser pulses at various repetition rates into sodalime glass. We investigate the effect the repetition rate and number of pulses on the size of the resulting structures. We identify the combinations of burst repetition rate and number of pulses within a burst for which accumulation of heat occurs. The threshold for heat accumulation depends on the number of pulses within a burst. The burst repetition rate and the number of pulses within a burst provide convenient control of the morphology of structures generated with high repetition rate femtosecond micromachining.

  10. CW laser strategies for simultaneous, multi-parameter measurements in high-speed gas flows

    NASA Technical Reports Server (NTRS)

    Di Rosa, M. D.; Philippe, L. C.; Arroyo, M. P.; Hanson, R. K.

    1992-01-01

    Strategies utilizing continuous wave (CW) lasers are considered which are capable of simultaneously measuring the flow parameters of velocity, temperature, and pressure at sampling rates exceeding 3 kHz. Velocity is determined from the Doppler shift of the spectral profile, temperature is extracted from intensity ratios of multiple lines, and pressure is measured from either the collision of broadening or the magnitude of absorption. Distinctions between strategies concern the specifics of probe spacies (NO, OH, O2, and H2O) in terms of nominal probe wavelength, equipment, and detection scheme. CW lasers were applied to path-integrated absorption measurements of transient shock-tube flows and spatially resolved laser-induced fluorescence measurements of underexpanded jets.

  11. High-speed laser anemometry based on spectrally resolved Rayleigh scattering

    NASA Technical Reports Server (NTRS)

    Seasholtz, Richard G.

    1991-01-01

    Laser anemometry in unseeded flows based on the measurement of the spectrum of Rayleigh scattered laser light is reviewed. The use of molecular scattering avoids the well known problems (particle lag, biasing effects, seed generation, seed injection) of seeded flows. The fundamental limits on velocity measurement accuracy are determined using maximum likelihood methods. Measurement of the Rayleigh spectrum with scanning Fabry-Perot interferometers is analyzed and accuracy limits are established for both single pass and multipass configurations. Multipass configurations have much higher selectivity and are needed for measurements where there is a large amount of excess noise caused by stray laser light. It is shown that Rayleigh scattering is particularly useful for supersonic and hypersonic flows. The results of the analysis are compared with measurements obtained with a Rayleigh scattering diagnostic developed for study of the exhaust plume of a small hydrogen-oxygen rocket, where the velocities are in the range of 1000 to 5000 m/sec.

  12. Ultra-fine pitch individually addressable visible laser arrays for high speed digital printing applications

    NASA Astrophysics Data System (ADS)

    Kowalski, O. P.; McDougall, S. D.; Qiu, B. C.; Masterton, G. H.; Armstrong, M. L.; Robertson, S.; Caldecott, S.; Marsh, J. H.

    2009-02-01

    An individually addressable visible semiconductor laser diode array with a 20 μm pitch is demonstrated that is highly suited for deployment in next-generation digital print systems. The array, operating at 660 nm, comprises 22 single mode lasers fabricated on a single GaInP/AlGaInP/GaAs substrate. The laser array is flip-chip bonded onto a patterned ceramic submount that enables the individual elements to be driven independently and is integrated into a 26-pin butterfly package. Arrays tested CW exhibit low threshold current (<20 mA per emitter), up to 50 mW output power per channel with a high slope efficiency (0.9 W/A) and a high characteristic temperature of over 100 K.

  13. High-speed measurement of an air transect's temperature shift heated by laser beam

    NASA Astrophysics Data System (ADS)

    Li, WenYu; Jiang, ZongFu; Xi, Fengjie; Li, Qiang; Xie, Wenke

    2005-02-01

    Laser beam heat the air on the optic path, Beam-deflection optical tomography is a non-intrusive method to measure the 2-dimension temperature distribution in the transect. By means of linear Hartmann Sensor at the rate of 27kHz, the optic path was heated by a 2.7μm HF laser, continuous and high time resolution gradients of optic phase were obtained. the result of analysing and calculation showed the temperament shift in the heated beam path was not higher than 50K when the HF laser power was 9W. The experiment showed that it is a practical non-intrusive temperature shift measurement method for a small area aero-optical medium.

  14. High-speed directly modulated 1.5μm quantum dot lasers

    NASA Astrophysics Data System (ADS)

    Banyoudeh, Saddam; Abdollahinia, Alireza; Eyal, Ori; Schnabel, Florian; Sichkovskyi, Vitalii; Eisenstein, Gadi; Reithmaier, Johann P.

    2016-03-01

    Due to the discrete density of states distribution and spatial localization of carriers in quantum dot (QD) material, the dynamics should be strongly enhanced in comparison to quantum well material. Based on improved 1.5 μm InAs/InGaAlAs/InP QD gain material short cavity ridge waveguide lasers were fabricated. Devices with cavity, lengths of 230 to 338 μm with high reflection coatings on the backside exhibit record value for any QD laser in small and large signal modulation performance with up to 15 GHz and 36 GBit/s, respectively, obtained at 14 °C. Due to the high temperature stability of threshold current and external differential efficiency, the lasers exhibit also nearly constant modulation bandwidth between 14-60 °C.

  15. High-speed high-sensitivity infrared spectroscopy using mid-infrared swept lasers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Childs, David T. D.; Groom, Kristian M.; Hogg, Richard A.; Revin, Dmitry G.; Cockburn, John W.; Rehman, Ihtesham U.; Matcher, Stephen J.

    2016-03-01

    Infrared spectroscopy is a highly attractive read-out technology for compositional analysis of biomedical specimens because of its unique combination of high molecular sensitivity without the need for exogenous labels. Traditional techniques such as FTIR and Raman have suffered from comparatively low speed and sensitivity however recent innovations are challenging this situation. Direct mid-IR spectroscopy is being speeded up by innovations such as MEMS-based FTIR instruments with very high mirror speeds and supercontinuum sources producing very high sample irradiation levels. Here we explore another possible method - external cavity quantum cascade lasers (EC-QCL's) with high cavity tuning speeds (mid-IR swept lasers). Swept lasers have been heavily developed in the near-infrared where they are used for non-destructive low-coherence imaging (OCT). We adapt these concepts in two ways. Firstly by combining mid-IR quantum cascade gain chips with external cavity designs adapted from OCT we achieve spectral acquisition rates approaching 1 kHz and demonstrate potential to reach 100 kHz. Secondly we show that mid-IR swept lasers share a fundamental sensitivity advantage with near-IR OCT swept lasers. This makes them potentially able to achieve the same spectral SNR as an FTIR instrument in a time x N shorter (N being the number of spectral points) under otherwise matched conditions. This effect is demonstrated using measurements of a PDMS sample. The combination of potentially very high spectral acquisition rates, fundamental SNR advantage and the use of low-cost detector systems could make mid-IR swept lasers a powerful technology for high-throughput biomedical spectroscopy.

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

    NASA Astrophysics Data System (ADS)

    Yang, Chuan; Zhang, Haibin

    2017-03-01

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

  17. Long Wavelength Multiple Quantum Well Lasers for High-Speed Modulation Applications

    DTIC Science & Technology

    1992-02-01

    Laboratory Air Force Systems Command Griffiss Air Force Base , NY 13441-5700 This report has been reviewed by the Rome Laboratory Public Affairs Office (PA...this document. 3 2. Technical Report 2.1 Introduction Early work on quantum well lasers for 1.3g.m operation was almost exclusively based upon LPE, and...InGaAlAs based (graded-index separate confinement heterostructure) GRIN-SCH quantum well laser at 1.3gm was among the first of a small number of papers

  18. Interferometry and high speed photography of laser-driven flyer plates

    SciTech Connect

    Paisley, D.L.; Montoya, N.I.; Stahl, D.B.; Garcia, I.A.

    1989-01-01

    Laser-driven thin (2-10-/mu/ thick) plates of aluminum and copper are accelerated to velocities /ge/5 km/s by a 1.06-/mu/ wavelength Nd:YAG 8-10 ns FWHM laser pulse at power densities 0.7-4.0 GW/cm/sup 2/. Accelerations /ge/10/sup 9/ km/s/sup 2/ have been achieved. The acceleration and velocity of these 0.4-1.0-mm-diameter plates are experimentally recorded by velocity interferometry (VISAR) and the planarity of impact by streak photography. 6 refs., 7 figs.

  19. Femtosecond laser micro-machined polyimide films for cell scaffold applications.

    PubMed

    Antanavičiūtė, Ieva; Šimatonis, Linas; Ulčinas, Orestas; Gadeikytė, Aušra; Abakevičienė, Brigita; Tamulevičius, Sigitas; Mikalayeva, Valeryia; Skeberdis, Vytenis Arvydas; Stankevičius, Edgaras; Tamulevičius, Tomas

    2016-12-11

    Engineering of sophisticated synthetic 3D scaffolds that allow controlling behavior and location of the cells requires advanced micro/nano fabrication techniques. Ultrafast laser micro-machining employing a 1030 nm wavelength Yb:KGW femtosecond laser and a micro-fabrication workstation for micro-machining of commercially available 12.7 and 25.4 µm thickness polyimide (PI) film was applied. Mechanical properties of the fabricated scaffolds, i.e., arrays of differently spaced holes, were examined via custom-built uniaxial micro-tensile testing and finite element method simulations. We demonstrate that experimental micro-tensile testing results could be numerically simulated and explained by 2-material model, assuming that 2-6 µm width rings around the holes possessed up to 5 times higher Young's modulus and yield stress compared with the rest of the laser intacted PI film areas of "dog-bone" shaped specimens. That was attributed to material modification around the micro-machined holes in the vicinity of the position of the focused laser beam track during trepanning drilling. We demonstrate that virgin PI films provide a suitable environment for the mobility, proliferation, and intercellular communication of human bone marrow mesenchymal stem cells and discuss how cell behavior varies on the micro-machined PI films with holes of different diameters (3.1, 8.4, and 16.7 µm) and hole spacing (30, 35, 40, and 45 µm). We conclude that the holes of 3.1 µm diameter were sufficient for metabolic and genetic communication through membranous tunneling tubes between cells residing on the opposite sides of PI film but prevented the trans-migration of cells through the holes. This article is protected by copyright. All rights reserved.

  20. The Laser MicroJet (LMJ): a multi-solution technology for high quality micro-machining

    NASA Astrophysics Data System (ADS)

    Mai, Tuan Anh; Richerzhagen, Bernold; Snowdon, Paul C.; Wood, David; Maropoulos, Paul G.

    2007-02-01

    The field of laser micromachining is highly diverse. There are many different types of lasers available in the market. Due to their differences in irradiating wavelength, output power and pulse characteristic they can be selected for different applications depending on material and feature size [1]. The main issues by using these lasers are heat damages, contamination and low ablation rates. This report examines on the application of the Laser MicroJet(R) (LMJ), a unique combination of a laser beam with a hair-thin water jet as a universal tool for micro-machining of MEMS substrates, as well as ferrous and non-ferrous materials. The materials include gallium arsenide (GaAs) & silicon wafers, steel, tantalum and alumina ceramic. A Nd:YAG laser operating at 1064 nm (infra red) and frequency doubled 532 nm (green) were employed for the micro-machining of these materials.

  1. High-speed surface functionalization by direct laser interference patterning (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Dyck, Tobias; Lasagni, Andrés.-Fabián.

    2017-03-01

    The material processing by two or more interfering laser beams, is referred to as Direct Laser Interference Patterning (DLIP). The periodic intensity pattern of the overlapping laser beams is used to ablate or modify the material so a functionalization of the surface is achieved. By adjusting the number, direction, intensity and polarization of the interfering beams, the detailed geometry of the intensity pattern can be shaped and the realizable feature sizes can be continuously adjusted within the micro- and submicrometer range. Consequently, the surface texture can be engineered and tailored to perfectly suit the needs of a given application. Typical applications of DLIP range from in- and out coupling of light in solar cells or organic LEDs over improvement of tribological properties in engine parts to security markings and decoration applications due to the shimmering effect of the periodic textures. On laboratory scale, an improvement over unprocessed surfaces has been demonstrated in all of these mentioned applications. However, so far the feed rates have not sufficed to allow an industrial application of the technology. Now, in a joint project of laser manufacturer, optics designer and engineering company, a machine platform has been developed which allows high surface processing speeds in an industrial environment. Feed rates in the range of square meters per minute (corresponding to about one billion features per second) can be achieved. With the help of this platform, DLIP can finally be lifted to industrial application.

  2. Method and apparatus for reducing quantization error in laser gyro test data through high speed filtering

    SciTech Connect

    Mark, J.G.; Brown, A.K.; Matthews, A.

    1987-01-06

    A method is described for processing ring laser gyroscope test data comprising the steps of: (a) accumulating the data over a preselected sample period; and (b) filtering the data at a predetermined frequency so that non-time dependent errors are reduced by a substantially greater amount than are time dependent errors; then (c) analyzing the random walk error of the filtered data.

  3. Aerodynamic distortion propagation calculation in application of high-speed target detection by laser

    NASA Astrophysics Data System (ADS)

    Zheng, Yonghui; Sun, Huayan; Zhao, Yanzhong; Chen, Jianbiao

    2015-10-01

    Active laser detection technique has a broad application prospect in antimissile and air defense, however the aerodynamic flow field around the planes and missiles cause serious distortion effect on the detecting laser beams. There are many computational fluid dynamics(CFD) codes that can predict the air density distribution and also the density fluctuations of the flow field, it's necessary for physical optics to be used to predict the distortion properties after propagation through the complex process. Aiming at the physical process of laser propagation in "Cat-eye" lenses and aerodynamic flow field for twice, distortion propagation calculation method is researched in this paper. In the minds of dividing the whole process into two parts, and tread the aero-optical optical path difference as a phase distortion, the incidence and reflection process are calculated using Collins formula and angular spectrum diffraction theory respectively. In addition, turbulent performance of the aerodynamic flow field is estimated according to the electromagnetic propagation theory through a random medium, the rms optical path difference and Strehl ratio of the turbulent optical distortion are obtained. Finally, Computational fluid mechanics and aero-optical distortion properties of the detecting laser beams are calculated with the hemisphere-on-cylinder turret as an example, calculation results are showed and analysed.

  4. High-speed energy efficient selective removal of large area copper layer by laser induced delamination

    NASA Astrophysics Data System (ADS)

    Kmetec, Blaž; Kovačič, Drago; Možina, Janez; Podobnik, Boštjan

    2009-07-01

    An indirect laser-induced method for selective removal of large copper areas from a printed circuit board is theoretically and experimentally investigated. The results show that the threshold condition for the process involves phase transition of the epoxy-based substrate resin. Optimal parameters for maximizing process speed are found and discussed.

  5. High speed pulsed laser cutting of LiCoO2 Li-ion battery electrodes

    NASA Astrophysics Data System (ADS)

    Lutey, Adrian H. A.; Fortunato, Alessandro; Carmignato, Simone; Fiorini, Maurizio

    2017-09-01

    Laser cutting of Li-ion battery electrodes represents an alternative to mechanical blanking that avoids complications associated with tool wear and allows assembly of different cell geometries with a single device. In this study, laser cutting of LiCoO2 Li-ion battery electrodes is performed at up to 5m /s with a 1064nm wavelength nanosecond pulsed fiber laser with a maximum average power of 500W and a repetition rate of up to 2MHz . Minimum average cutting power for cathode and anode multi-layer films is established for 12 parameter groups with velocities over the range 1 - 5m /s , varying laser pulse fluence and overlap. Within the tested parameter range, minimum energy per unit cut length is found to decrease with increasing repetition rate and velocity. SEM analysis of the resulting cut edges reveals visible clearance widths in the range 20 - 50 μm , with cut quality found to improve with velocity due to a reduction in lateral heat conduction losses. Raman line map spectra reveal changes in the cathode at 60 μm from the cut edge, where bands at 486cm-1 and 595cm-1 , corresponding to the Eg and A1g modes of LiCoO2 , are replaced with a single wide band centered at 544cm-1 , and evidence of carbon black is no longer present. No changes in Raman spectra are observed in the anode. The obtained results suggest that further improvements in cutting efficiency and quality could be achieved by increasing the repetition rate above 2MHz , thereby improving ablation efficiency of the metallic conductor layers. The laser source utilized in the present study nonetheless represents an immediately available solution for repeatability and throughput that are superior to mechanical blanking.

  6. Investigation of temporal contrast effects in femtosecond pulse laser micromachining of metals.

    SciTech Connect

    Campbell, Benjamin (Pennsylvania State University, Freeport, PA); Palmer, Jeremy Andrew

    2006-06-01

    Femtosecond pulse laser drilling has evolved to become a preferred process for selective (maskless) micromachining in a variety of materials, including metals, polymers, semiconductors, ceramics, and living tissue. Manufacturers of state-of-the-art femtosecond laser systems advertise the inherent advantage of micromachining with ultra short pulses: the absence of a heat affected zone. In the ideal case, this leads to micro and nano scale features without distortion due to melt or recast. However, recent studies have shown that this is limited to the low fluence regime in many cases. High dynamic range autocorrelation studies were performed on two commercial Ti:sapphire femtosecond laser systems to investigate the possible presence of a nanosecond pedestal in the femtosecond pulse produced by chirped pulse amplification. If confirmed, nanosecond temporal phenomena may explain many of the thermal effects witnessed in high fluence micromachining. The material removal rate was measured in addition to feature morphology observations for percussion micro drilling of metal substrates in vacuum and ambient environments. Trials were repeated with proposed corrective optics installed, including a variable aperture and a nonlinear frequency doubling crystal. Results were compared. Although the investigation of nanosecond temporal phenomena is ongoing, early results have confirmed published accounts of higher removal rates in a vacuum environment.

  7. Digital high-speed camera system for combustion research using UV-laser diagnostic under microgravity at Bremen drop tower

    NASA Astrophysics Data System (ADS)

    Renken, Hartmut; Bolik, T.; Eigenbrod, Ch.; Koenig, Jens; Rath, Hans J.

    1997-04-01

    A digital high-speed camera- and recording system for 2D UV- laser spectroscopy was recently completed at Bremen drip tower. At the moment the primary users are the microgravity combustion researchers. The current project studies the reaction zones during the process of combustion. Particularly OH-radicals are detected 2D by using the method of laser induced predissociation fluorescence (LIPF). A pulsed high-energy excimer lasersystem combined with a two- staged intensified CCD-camera allows a repetition rate of 250 images per second, according to the maximum laser pulse repetition. The laser system is integrated at the top of the 110 m high evacuatable drop tube. Motorized mirrors are necessary to achieve a stable beam position within the area of interest during the drop of the experiment-capsule. The duration of 1 drop will be 4.7 seconds. About 1500 images are captured and stored onboard the drop capsule 96 Mbyte RAM image storagesystem. After saving capsule and data, a special PC-based image processing software visualizes the movies and extracts physical information out of the images. Now, after two and a half years of development the system is working operational and capable of high temporal 2D LIPF- measuring of OH, H2O, O2 and CO concentrations and 2D temperature distribution of these species.

  8. Laser-triangulation device for in-line measurement of road texture at medium and high speed

    NASA Astrophysics Data System (ADS)

    Cigada, Alfredo; Mancosu, Federico; Manzoni, Stefano; Zappa, Emanuele

    2010-10-01

    The knowledge of the friction coefficient between road and tyres is a very precious information to implement vehicle active control, especially considering the optimisation of the braking action. One of the most important parameters able to influence such a coefficient is the road texture (microtexture and macrotexture). Although different methods are now available to perform reliable texture measurements, no well-established techniques currently exist for measuring the pavement texture at medium-high speed with real time data analysis during the usual vehicle operations. This paper presents a method, based on two identical industrial laser-triangulation displacement transducers, allowing to get real time reliable road micro and macrotexture measurements during standard vehicle operations, even at medium and high speed. The presence of two transducers also allows to estimate the instantaneous vehicle speed, which is needed to obtain the road texture from the sensor time-histories. This means that the presented system can be considered as a stand-alone device able to give as an output the road texture (micro and macro) and also the vehicle speed without any other input. The paper also underlines the advantages of this method and its drawbacks. The method reliability is evidenced by some real time outdoor tests on the different road surfaces of the Pirelli test track and at different vehicle speeds.

  9. Real-time monitoring of laser powder bed fusion process using high-speed X-ray imaging and diffraction

    DOE PAGES

    Zhao, Cang; Fezzaa, Kamel; Cunningham, Ross W.; ...

    2017-06-15

    Here, we employ the high-speed synchrotron hard X-ray imaging and diffraction techniques to monitor the laser powder bed fusion (LPBF) process of Ti-6Al-4V in situ and in real time. We demonstrate that many scientifically and technologically significant phenomena in LPBF, including melt pool dynamics, powder ejection, rapid solidification, and phase transformation, can be probed with unprecedented spatial and temporal resolutions. In particular, the keyhole pore formation is experimentally revealed with high spatial and temporal resolutions. The solidification rate is quantitatively measured, and the slowly decrease in solidification rate during the relatively steady state could be a manifestation of the recalescencemore » phenomenon. The high-speed diffraction enables a reasonable estimation of the cooling rate and phase transformation rate, and the diffusionless transformation from β to α’ phase is evident. The data present here will facilitate the understanding of dynamics and kinetics in metal LPBF process, and the experiment platform established will undoubtedly become a new paradigm for future research and development of metal additive manufacturing.« less

  10. High-speed mass-transport phenomena during carburization of aluminum alloy by laser plasma treatment

    NASA Astrophysics Data System (ADS)

    Fariaut, F.; Boulmer-Leborgne, C.; Semmar, N.; Le Menn, E.

    2006-04-01

    In the excimer laser carburizing process reported here, aluminum alloy samples have been treated in a propylene atmosphere, producing aluminum carbide surface layers. The layers have been characterized by nuclear reaction analysis that has shown carbon incorporation. X-ray diffraction at grazing incidence has evidenced aluminum carbide (Al4C3) phase. This study helps the understanding of the incorporation mechanisms of carbon in a surface. A micro-thermocapillary effect induced by heterogeneous surface formation has been evidenced. This original mass-transport phenomenon is very efficient in improving the carbon incorporation yield and hence in obtaining carbide layers several μm in thickness with a reduced laser pulse number. In order to obtain this micro-thermocapillary effect, the binary diagram of ceramic compounds must contain a peritectic.

  11. Characterization of a Laser-Generated Perturbation in High-Speed Flow for Receptivity Studies

    NASA Technical Reports Server (NTRS)

    Chou, Amanda; Schneider, Steven P.; Kegerise, Michael A.

    2014-01-01

    A better understanding of receptivity can contribute to the development of an amplitude-based method of transition prediction. This type of prediction model would incorporate more physics than the semi-empirical methods, which are widely used. The experimental study of receptivity requires a characterization of the external disturbances and a study of their effect on the boundary layer instabilities. Characterization measurements for a laser-generated perturbation were made in two different wind tunnels. These measurements were made with hot-wire probes, optical techniques, and pressure transducer probes. Existing methods all have their limitations, so better measurements will require the development of new instrumentation. Nevertheless, the freestream laser-generated perturbation has been shown to be about 6 mm in diameter at a static density of about 0.045 kg/cubic m. The amplitude of the perturbation is large, which may be unsuitable for the study of linear growth.

  12. 1.55 µm high speed low chirp electroabsorption modulated laser arrays based on SAG scheme.

    PubMed

    Cheng, Yuanbing; Wang, Qi Jie; Pan, Jiaoqing

    2014-12-15

    We demonstrate a cost-effective 1.55 µm low chirp 4 × 25 Gbit/s electroabsorption modulated laser (EML) array with 0.8 nm channel spacing by varying ridge width of the lasers and using selective area growth (SAG) integration scheme. The devices for all the 4 channels within the EML array show uniform threshold currents around 18 mA and high SMSRs over 45 dB. The output optical power of each channel is about 9 mW at an injection current of 100 mA. The typical chirp value of single EML measured by a fiber resonance method varied from 2.2 to -4 as the bias voltage was increased from 0 V to 2.5 V. These results show that the EML array is a suitable light source for 100 Gbit/s optical transmissions.

  13. High-Speed Laser Scanner Maps a Surface in Three Dimensions

    NASA Technical Reports Server (NTRS)

    Lavelle, Joseph; Schuet, Stefan

    2006-01-01

    A scanning optoelectronic instrument generates the digital equivalent of a threedimensional (X,Y,Z) map of a surface that spans an area with resolution on the order of 0.005 in. ( 0.125mm). Originally intended for characterizing surface flaws (e.g., pits) on space-shuttle thermal-insulation tiles, the instrument could just as well be used for similar purposes in other settings in which there are requirements to inspect the surfaces of many objects. While many commercial instruments can perform this surface-inspection function, the present instrument offers a unique combination of capabilities not available in commercial instruments. This instrument utilizes a laser triangulation method that has been described previously in NASA Tech Briefs in connection with simpler related instruments used for different purposes. The instrument includes a sensor head comprising a monochrome electronic camera and two lasers. The camera is a high-resolution

  14. Frequency tuning of polarization oscillations: Toward high-speed spin-lasers

    SciTech Connect

    Lindemann, Markus Gerhardt, Nils C.; Hofmann, Martin R.; Pusch, Tobias; Michalzik, Rainer

    2016-01-25

    Spin-controlled vertical-cavity surface-emitting lasers (spin-VCSELs) offer a high potential to overcome several limitations of conventional purely charged-based laser devices. Presumably, the highest potential of spin-VCSELs lies in their ultrafast spin and polarization dynamics, which can be significantly faster than the intensity dynamics in conventional devices. Here, we experimentally demonstrate polarization oscillations in spin-VCSELs with frequencies up to 44 GHz. The results show that the oscillation frequency mainly depends on the cavity birefringence, which can be tuned by applying mechanical strain to the VCSEL structure. A tuning range of about 34 GHz is demonstrated. By measuring the polarization oscillation frequency and the birefringence governed mode splitting as a function of the applied strain simultaneously, we are able to investigate the correlation between birefringence and polarization oscillations in detail. The experimental findings are compared to numerical calculations based on the spin-flip model.

  15. Laser treatment of powder high-speed steels with prior vacuum hardening and surface impregnation

    NASA Astrophysics Data System (ADS)

    Tarasov, A. N.

    2000-02-01

    Laser treatment of powder steels R0M6F3-MP, R6M5-MP, and R6M5-P preliminarily subjected to vacuum quenching or vacuum cyanidation with quenching promotes the formation of surface layers having an elevated wear resistance under contact-abrasive action, for example, in machining ceramic and refractory heat-resistant materials or under the surface action of ion-plasma jets of a high specific power. The structure of laser-hardened surface layers consists of pseudo-acicular martensite and an elevated amount of finely dispersed carbides, which prevents spalling and chipping of thin functional edges in blades for continuous machining under cyclic thermal loads.

  16. High-speed droplet generation on demand driven by pulse laser-induced cavitation.

    PubMed

    Park, Sung-Yong; Wu, Ting-Hsiang; Chen, Yue; Teitell, Michael A; Chiou, Pei-Yu

    2011-03-21

    We report on a pulse laser-driven droplet generation (PLDG) mechanism that enables on-demand droplet generation at rates up to 10,000 droplets per second in a single-layer PDMS-based microfluidic device. Injected droplet volumes can be continuously tuned between 1 pL and 150 pL with less than 1% volume variation. This journal is © The Royal Society of Chemistry 2011

  17. High-speed laser anemometry based on spectrally resolved Rayleigh scattering

    NASA Technical Reports Server (NTRS)

    Seasholtz, R. G.

    1991-01-01

    Laser anemometry in unseeded flows based on the measurement of the spectrum of Rayleigh scattered laser light is reviewed. The use of molecular scattering avoids the well-known problems (particle lag, biasing effects, seed generation, seed injection) of seeded flows. The fundamental limits on velocity measurement accuracy are determined using maximum likelihood methods. Measurement of the Rayleigh spectrum with scanning Fabry-Perot interferometers is analyzed and accuracy limits are established for both single pass and multi-pass configurations. Multi-pass configurations have much higher selectivity and are needed for measurements where there is a large amount of excess noise caused by stray laser light. It is shown that Rayleigh scattering is particularly useful for supersonic and hypersonic flows. The results of the analysis are compared with measurements obtained with a Rayleigh scattering diagnostic developed for study of the exhaust plume of a small hydrogen-oxygen rocket, where the velocities are in the range 1000 to 5000 m/sec.

  18. High-speed mid-infrared hyperspectral imaging using quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Kelley, David B.; Goyal, Anish K.; Zhu, Ninghui; Wood, Derek A.; Myers, Travis R.; Kotidis, Petros; Murphy, Cara; Georgan, Chelsea; Raz, Gil; Maulini, Richard; Müller, Antoine

    2017-05-01

    We report on a standoff chemical detection system using widely tunable external-cavity quantum cascade lasers (ECQCLs) to illuminate target surfaces in the mid infrared (λ = 7.4 - 10.5 μm). Hyperspectral images (hypercubes) are acquired by synchronously operating the EC-QCLs with a LN2-cooled HgCdTe camera. The use of rapidly tunable lasers and a high-frame-rate camera enables the capture of hypercubes with 128 x 128 pixels and >100 wavelengths in <0.1 s. Furthermore, raster scanning of the laser illumination allowed imaging of a 100-cm2 area at 5-m standoff. Raw hypercubes are post-processed to generate a hypercube that represents the surface reflectance relative to that of a diffuse reflectance standard. Results will be shown for liquids (e.g., silicone oil) and solid particles (e.g., caffeine, acetaminophen) on a variety of surfaces (e.g., aluminum, plastic, glass). Signature spectra are obtained for particulate loadings of RDX on glass of <1 μg/cm2.

  19. Calculus migration characterization during Ho:YAG laser lithotripsy by high-speed camera using suspended pendulum method.

    PubMed

    Zhang, Jian James; Rajabhandharaks, Danop; Xuan, Jason Rongwei; Chia, Ray W J; Hasenberg, Thomas

    2017-07-01

    Calculus migration is a common problem during ureteroscopic laser lithotripsy procedure to treat urolithiasis. A conventional experimental method to characterize calculus migration utilized a hosting container (e.g., a "V" grove or a test tube). These methods, however, demonstrated large variation and poor detectability, possibly attributed to the friction between the calculus and the container on which the calculus was situated. In this study, calculus migration was investigated using a pendulum model suspended underwater to eliminate the aforementioned friction. A high-speed camera was used to study the movement of the calculus which covered zero order (displacement), first order (speed), and second order (acceleration). A commercialized, pulsed Ho:YAG laser at 2.1 μm, a 365-μm core diameter fiber, and a calculus phantom (Plaster of Paris, 10 × 10 × 10 mm(3)) was utilized to mimic laser lithotripsy procedure. The phantom was hung on a stainless steel bar and irradiated by the laser at 0.5, 1.0, and 1.5 J energy per pulse at 10 Hz for 1 s (i.e., 5, 10, and 15 W). Movement of the phantom was recorded by a high-speed camera with a frame rate of 10,000 FPS. The video data files are analyzed by MATLAB program by processing each image frame and obtaining position data of the calculus. With a sample size of 10, the maximum displacement was 1.25 ± 0.10, 3.01 ± 0.52, and 4.37 ± 0.58 mm for 0.5, 1, and 1.5 J energy per pulse, respectively. Using the same laser power, the conventional method showed <0.5 mm total displacement. When reducing the phantom size to 5 × 5 × 5 mm(3) (one eighth in volume), the displacement was very inconsistent. The results suggested that using the pendulum model to eliminate the friction improved sensitivity and repeatability of the experiment. A detailed investigation on calculus movement and other causes of experimental variation will be conducted as a future study.

  20. High-speed imaging of Raleigh-Taylor instabilities in laser-driven plates

    NASA Astrophysics Data System (ADS)

    Frank, Alan M.; Gillespie, Calvin H.; Trott, Wayne M.

    1997-05-01

    We have previously reported our observations of the dynamic behavior of laser driven plates. Recent improvements and modification of the imaging techniques have identified and provided measurements of Raleigh-Taylor (R-T) instabilities that occur in these events. The microscope system in the LLNL Micro Detonics Facility, was converted to an epi- illuminated polarization configuration. A double pulse nanosecond illuminator and a second independently focusable frame camera were also added to the system. A laser driven plate, that is a dense solid driven by a laser heated, lower density plasma, is inherently R-T unstable. The characteristics and growth of the instability determine whether or not the plate remains intact. In earlier reports we correlated the surface patterning of thin plates with the fiber-optical transmission modes. In subsequent experiments we noted that the plasma burn through patterning in thin plates and the surface patterning of thicker plates did not correspond to the thin plate early time patterning. These observations led to the suspicion of R-T instability. A series of experiments correlating plate thickness and pattern spatial frequency has verified the instability. The plates are aluminum, deposited on the ends of optical fibers. They are launched by a YAG laser pulse traveling down the fiber. Plate velocities are several kilometers per second and characteristic dimensions of the instabilities are a few to tens of microns. Several techniques were used to examine the plates, the most successful being specularly reflecting polarization microscopy looking directly at the plate as it flies toward the camera. These images gave data on the spatial frequencies of the instabilities but could not give the amplitudes. To measure the amplitude of the instability a semi-transparent witness plate was placed a known distance from the plate. As above, the plate was observed using the polarization microscope but using the streak camera as the detector

  1. Cognitive high speed defect detection and classification in MWIR images of laser welding

    NASA Astrophysics Data System (ADS)

    Lapido, Yago L.; Rodriguez-Araújo, Jorge; García-Díaz, Antón; Castro, Gemma; Vidal, Félix; Romero, Pablo; Vergara, Germán.

    2015-07-01

    We present a novel approach for real-time defect detection and classification in laser welding processes based on the use of uncooled PbSe image sensors working in the MWIR range. The spatial evolution of the melt pool was recorded and analyzed during several welding procedures. A machine learning approach was developed to classify welding defects. Principal components analysis (PCA) is used for dimensionality reduction of the melt pool data. This enhances classification results and enables on-line classification rates close to 1 kHz with non-optimized code prototyped in Python. These results point to the feasibility of real-time defect detection.

  2. Portable laser synthesizer for high-speed multi-dimensional spectroscopy

    DOEpatents

    Demos, Stavros G [Livermore, CA; Shverdin, Miroslav Y [Sunnyvale, CA; Shirk, Michael D [Brentwood, CA

    2012-05-29

    Portable, field-deployable laser synthesizer devices designed for multi-dimensional spectrometry and time-resolved and/or hyperspectral imaging include a coherent light source which simultaneously produces a very broad, energetic, discrete spectrum spanning through or within the ultraviolet, visible, and near infrared wavelengths. The light output is spectrally resolved and each wavelength is delayed with respect to each other. A probe enables light delivery to a target. For multidimensional spectroscopy applications, the probe can collect the resulting emission and deliver this radiation to a time gated spectrometer for temporal and spectral analysis.

  3. High-speed laser-launched flyer impacts studied with ultrafast photography and velocimetry

    SciTech Connect

    Banishev, Alexandr A.; Shaw, William L.; Bassett, Will P.; Dlott, Dana D.

    2016-02-16

    Pulsed lasers can launch thin metal foils at km s-1, but for precision measurements in shock compression science and shock wave spectroscopy, where one-dimensional shock compression is vital, flyer plate impacts with targets must have a high degree of flatness and minimal tilt, and the flyer speeds and impact times at the target must be highly reproducible. We have developed an apparatus that combines ultrafast stroboscopic optical microscopy with photon Doppler velocimetry to study impacts of laser-launched Al and Cu flyer plates with flat, transparent glass targets. The flyer plates were 0.5 mm in diameter, and ranged from 12-100 μm thick, with flyer speeds up to 6.25 km s-1. The velocity variations over 30-60 launches from the same flyer plate optic can be as low as 0.6%, and the impact time variations can be as low as 0.8 ns. Stroboscopic image streams (reconstructed movies) show uniform, flat impacts with a glass target. As a result, these stroboscopic images can be used to estimate the tilt in the flyer-target impact to be <1mrad.

  4. Turbulence measurements in high-speed flows using the Focusing Laser Differential Interferometer

    NASA Astrophysics Data System (ADS)

    Fulghum, Matthew; Settles, Gary

    2013-11-01

    The Focusing Laser Differential Interferometer (FLDI) was invented by Smeets at ISL in the 1970s, and was used recently by Parziale in the CalTech T5 shock tunnel. It is a relatively-simple, non-imaging common-path interferometer for measuring refractive signals from transition and turbulence, and it has a unique ability to look through facility windows, ignore sidewall boundary-layers and vibration, and concentrate only on the signal near a pair of sharp beam foci in the core flow. Benchtop experiments using a turbulent helium jet in air demonstrate focusing ability, frequency response, unwanted signal rejection, and ease of use. The FLDI is then used to measure freestream turbulence intensity and spectra in the PSU supersonic wind tunnel at Mach 3, with results compared to hot-wire-anemometer data. A special feature of the FLDI instrument used here is the replacement of traditional fixed Wollaston prisms with variable Sanderson prisms for laser-beam separation and recombination. Research sponsored by AEDC Hypervelocity Tunnel 9.

  5. High-speed laser-launched flyer impacts studied with ultrafast photography and velocimetry

    DOE PAGES

    Banishev, Alexandr A.; Shaw, William L.; Bassett, Will P.; ...

    2016-02-16

    Pulsed lasers can launch thin metal foils at km s-1, but for precision measurements in shock compression science and shock wave spectroscopy, where one-dimensional shock compression is vital, flyer plate impacts with targets must have a high degree of flatness and minimal tilt, and the flyer speeds and impact times at the target must be highly reproducible. We have developed an apparatus that combines ultrafast stroboscopic optical microscopy with photon Doppler velocimetry to study impacts of laser-launched Al and Cu flyer plates with flat, transparent glass targets. The flyer plates were 0.5 mm in diameter, and ranged from 12-100 μmmore » thick, with flyer speeds up to 6.25 km s-1. The velocity variations over 30-60 launches from the same flyer plate optic can be as low as 0.6%, and the impact time variations can be as low as 0.8 ns. Stroboscopic image streams (reconstructed movies) show uniform, flat impacts with a glass target. As a result, these stroboscopic images can be used to estimate the tilt in the flyer-target impact to be <1mrad.« less

  6. Picosecond laser micromachining of nitinol and platinum-iridium alloy for coronary stent applications

    NASA Astrophysics Data System (ADS)

    Muhammad, N.; Whitehead, D.; Boor, A.; Oppenlander, W.; Liu, Z.; Li, L.

    2012-03-01

    The demand for micromachining of coronary stents by means of industrial lasers rises quickly for treating coronary artery diseases, which cause more than one million deaths each year. The most widely used types of laser for stent manufacturing are Nd:YAG laser systems with a wavelength of 1064 nm with pulse lengths of 10-3-10-2 seconds. Considerable post-processing is required to remove heat-affected zones (HAZ), and to improve surface finishes and geometry. Using a third harmonic laser radiation of picosecond laser (6×10-12 s pulse duration) in UV range, the capability of the picosecond laser micromachining of nitinol and platinum-iridium alloy for coronary stent applications are presented. In this study dross-free cut of nitinol and platinum-iridium alloy tubes are demonstrated and topography analysis of the cut surface is carried out. The HAZ characteristics have been investigated by means of microscopic examinations and measurement of micro-hardness distribution near the cut zones.

  7. Non-invasive seedingless measurements of the flame transfer function using high-speed camera-based laser vibrometry

    NASA Astrophysics Data System (ADS)

    Gürtler, Johannes; Greiffenhagen, Felix; Woisetschläger, Jakob; Haufe, Daniel; Czarske, Jürgen

    2017-06-01

    The characterization of modern jet engines or stationary gas turbines running with lean combustion by means of swirl-stabilized flames necessitates seedingless optical field measurements of the flame transfer function, i.e. the ratio of the fluctuating heat release rate inside the flame volume, the instationary flow velocity at the combustor outlet and the time average of both quantities. For this reason, a high-speed camera-based laser interferometric vibrometer is proposed for spatio-temporally resolved measurements of the flame transfer function inside a swirl-stabilized technically premixed flame. Each pixel provides line-of-sight measurements of the heat release rate due to the linear coupling to fluctuations of the refractive index along the laser beam, which are based on density fluctuations inside the flame volume. Additionally, field measurements of the instationary flow velocity are possible due to correlation of simultaneously measured pixel signals and the known distance between the measurement positions. Thus, the new system enables the spatially resolved detection of the flame transfer function and instationary flow behavior with a single measurement for the first time. The presented setup offers single pixel resolution with measurement rates up to 40 kHz at an maximum image resolution of 256 px x 128 px. Based on a comparison with reference measurements using a standard pointwise laser interferometric vibrometer, the new system is validated and a discussion of the measurement uncertainty is presented. Finally, the measurement of refractive index fluctuations inside a flame volume is demonstrated.

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

    NASA Astrophysics Data System (ADS)

    Upputuri, Paul Kumar; Pramanik, Manojit

    2016-03-01

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

  9. High-speed and crack-free direct-writing of microchannels on glass by an IR femtosecond laser

    NASA Astrophysics Data System (ADS)

    Bulushev, Evgeny; Bessmeltsev, Victor; Dostovalov, Alexandr; Goloshevsky, Nikolay; Wolf, Alexey

    2016-04-01

    Fabrication of high-resolution 3D structures with laser radiation on the surface of brittle materials has always been a challenging task. Even with femtosecond laser machining, micro-cracks and edge chipping occur. In order to evaluate processing modes optimal both in quality and productivity, we investigated high-speed (50 kHz) femtosecond laser processing of BK7 glass with the use of design of experiments and regression analysis. An automated inspection technique was developed to extract quality characteristics of test-objects. A regression model was obtained appropriate to fabricate microchannels with a predefined depth in the range of 1-30 μm with average accuracy of 5%. It was found that high quality machining modes are in the range of 0.91-2.27 μJ energy pulses, overlap of 53-62%, three and more number of passes. A material removal rate higher than 0.3 mm3/min was reached and microfluidic structures were formed based on data obtained.

  10. Laser micromachined and laminated microchannel components for chemical sensors and heat transfer applications

    NASA Astrophysics Data System (ADS)

    Martin, Peter M.; Bennett, Wendy D.; Hammerstrom, D. J.; Johnston, John W.; Matson, Dean W.

    1997-09-01

    The fabrication of microchannel chemical sensors with seven laminated individual functional modules is described. The sensors, used to detect chromium in nuclear and chemical waste streams, were fabricated using laser micromachining, bulk silicon micromachining, photolithographic techniques, sputter coating deposition, and anodic and adhesive bonding processes. The size of the sensor was 2 cm by 2.2 cm, with a total thickness of 2.2 cm. It consisted of two or more reservoir modules to hold the liquids being evaluate, two or more micropump modules to pump the liquids through the sensor, a chemical mixing module, a reaction module, and a sensor module with electrical circuitry for connection to external measurement equipment. The fluids were directed through the layers by interconnecting flow channels. The reservoir modules were fabricated by machining Pyrex and anodic bonding to silicon. The chemical mixing module was fabricated by wet etching Pyrex and anodic bonding to silicon. The reaction module contained a serpentine 200- micrometers -wide channel, and was formed by laser micromachining polyimide. The first prototype of this sensor employed external micropumps, while the second prototype will use off-the-shelf piezoelectric micropumps. The detector layer consisted of iridium, silver, and platinum sensor pads connected to gold contact strips. The modules were joined using adhesive bonding, and an electrostatic technique was used for silicon-Pyrex bonding.

  11. MQW electroabsorption modulator-integrated DFB laser modules for high-speed transmission

    NASA Astrophysics Data System (ADS)

    Zhao, Q.; Pan, J. Q.; Zhang, J.; Li, B. X.; Zhou, F.; Wang, B. J.; Wang, L. F.; Zhao, L. J.; Zhou, G. T.; Wang, W.

    2006-06-01

    Details of the design, fabrication and testing of a strained InGaAsP/InGaAsP multiple quantum well (MQW) electroabsorption modulator (EAM) monolithically integrated with a DFB laser by ultra-low-pressure selective area growth (SAG) are presented. The method greatly simplifies the integration process. A study of the controllability of band-gap energy by SAG has been performed. After being completely packaged in a seven-pin butterfly compact module, the device successfully performs 10 Gb s-1 nonreturn to zero (NRZ) operation on uncompensated transmission span >53 km in a standard fibre with a 8.7 dB dynamic extinction ratio. A receiver sensitivity of -18.9 dBm at a bit error rate (BER) of 10-10 is confirmed. 10 GHz short pulse trains with 15.3 ps pulsewidth have also been generated.

  12. Performance of laser Doppler velocimeter with polydisperse seed particles in high speed flows

    NASA Technical Reports Server (NTRS)

    Samimy, M.; Bhattacharyya, S.; Abu-Hijleh, B. A./K.

    1988-01-01

    The flowfield behind an oblique shock wave, where the LDV measured velocities are seed particle size dependent, was used to investigate the effects of LDV system parameters on the range of detectable polydisperse seed particles. The parameters included frequency shifting, laser power, scattered signal amplification level, and number of required fringe crossings. The results showed that with polydisperse seed particles ranging from 0.1 to 4.0 microns available in the flow, the average diameter of the detected particles could change from 0.2 to 3.0 microns by changing different LDV system parameters. The effects of this shift in the range of detectable particles on the frequency response of LDV was discussed.

  13. Performance of laser Doppler velocimeter with polydisperse seed particles in high-speed flows

    NASA Technical Reports Server (NTRS)

    Samimy, M.; Abu-Hijleh, B. A. K.

    1989-01-01

    The flowfield behind an oblique shock wave, where the LDV measured velocities are seed-particle-size dependent, was used to investigate the effects of LDV system parameters on the range of detectable polydisperse seed particles. The parameters included frequency shifting, laser power, scattered signal amplification level, and number of required fringe crossings. The results showed that with polydisperse seed particles ranging from 0.1 to 4.0 microns available in the flow, the average diameter of the detected particles could change from 0.2 to 3.0 microns by changing different LDV system parameters. The effects of this shift in the range of detectable particles on the frequency response of LDV are discussed.

  14. Pulsed UV and ultrafast laser micromachining of surface structures

    NASA Astrophysics Data System (ADS)

    Apte, Paul; Sykes, Neil

    2015-07-01

    We describe and compare the cutting and patterning of various "difficult" materials using pulsed UV Excimer, picosecond and femtosecond laser sources. Beam delivery using both fast galvanometer scanners and scanning mask imaging are described. Each laser source has its own particular strengths and weaknesses, and the optimum choice for an application is also decided by financial constraints. With some materials notable improvements in process quality have been observed using femtosecond lasers compared to picosecond lasers, which makes for an interesting choice now that cost effective reliable femtosecond systems are increasingly available. By contrast Pulsed UV Excimer lasers offer different imaging characteristics similar to mask based Lithographic systems and are particularly suited to the processing of polymers. We discuss optimized beam delivery techniques for these lasers.

  15. High-speed identification of polymers by laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Moench, Ingo; Sattmann, R.; Noll, Reinhard

    1997-09-01

    One way to reduce the increasing waste streams of used polymers is an efficient material recycling. This requires a technology for the separation of polymer mixtures into different material fractions. For this purpose the principal suitability of laser-induced breakdown spectroscopy was investigated. Plasma emission spectra of LDPE, HDPE, PP, PET, PVC, and PS were studied. Basic investigations were performed in order to assess the influence of different measurement parameters and to optimize the analytical performance. More than 140 spectra lines are identified, which can be related to C, H, O, N, C2, CN and CH from the bulk material and the atmosphere and to Al, Ca, Cu, Fe, Mg, Sn, Ti and Zn from additives of the polymer. Estimated detection limits of down to 2 ppm are achieved for metallic additives. Different artificial neural networks were tested for the evaluation of the spectra. PET and PVC can be identified unambiguously detecting the characteristic elements oxygen and chlorine. For plastics, which differ in their contents of inorganic additives, the line emission of additives can be used as `fingerprints' of the plastics. In this way identification accuracies of 87% to 100% for PE, PP, PET and PVC are achieved.

  16. A laser-optical sensor system for blade vibration detection of high-speed compressors

    NASA Astrophysics Data System (ADS)

    Neumann, Mathias; Dreier, Florian; Günther, Philipp; Wilke, Ulrich; Fischer, Andreas; Büttner, Lars; Holzinger, Felix; Schiffer, Heinz-Peter; Czarske, Jürgen

    2015-12-01

    Improved efficiency as well as increased lifetime of turbines and compressors are important goals in turbomachinery development. A significant enhancement to accomplish these aims can be seen in online monitoring of the operating parameters of the machines. During the operation of compressors it is of high interest to predict critical events like flutter or stall which can be achieved by observing blade deformations and vibrations. We have developed a laser Doppler distance sensor (LDDS), which is capable of simultaneously measuring the radial blade expansions, the circumferential blade deflections as well as the circumferential velocities of the rotor blade tips. As a result, an increase of blade vibrations is measured before stall at characteristic frequencies. While the detected vibration frequencies and the vibration increase are in agreement with the measurement results of a commercial capacitive blade tip timing system, the measured values of the vibration amplitudes differ by a factor of three. This difference can be mainly attributed to the different measurement locations and to the different measurement approaches. Since the LDDS is applicable to metal as well as ceramic, carbon-fiber and glass-fiber reinforced composite blades, a universally applicable sensor system for stall prediction and status monitoring is presented.

  17. High-speed automated DNA sequencing utilizing from-the-side laser excitation

    NASA Astrophysics Data System (ADS)

    Westphall, Michael S.; Brumley, Robert L., Jr.; Buxton, Erin C.; Smith, Lloyd M.

    1995-04-01

    The Human Genome Initiative is an ambitious international effort to map and sequence the three billion bases of DNA encoded in the human genome. If successfully completed, the resultant sequence database will be a tool of unparalleled power for biomedical research. One of the major challenges of this project is in the area of DNA sequencing technology. At this time, virtually all DNA sequencing is based upon the separation of DNA fragments in high resolution polyacrylamide gels. This method, as generally practiced, is one to two orders of magnitude too slow and expensive for the successful completion of the Human Genome projection. One reasonable approach is improved sequencing of DNA fragments is to increase the performance of such gel-based sequencing methods. Decreased sequencing times may be obtained by increasing the magnitude of the electric field employed. This is not possible with conventional sequencing, due to the fact that the additional heat associated with the increased electric field cannot be adequately dissipated. Recent developments in the use of thin gels have addressed this problem. Performing electrophoresis in ultrathin (50 to 100 microns) gels greatly increases the heat transfer efficiency, thus allowing the benefits of larger electric fields to be obtained. An increase in separation speed of about an order of magnitude is readily achieved. Thin gels have successfully been used in capillary and slab formats. A detection system has been designed for use with a multiple fluorophore sequencing strategy in horizontal ultrathin slab gels. The system employs laser through-the-side excitation and a cooled CCD detector; this allows for the parallel detection of up to 24 sets of four fluorescently labeled DNA sequencing reactions during their electrophoretic separation in ultrathin (115 micrometers ) denaturing polyacrylamide gels. Four hundred bases of sequence information is obtained from 100 ng of M13 template DNA in an hour, corresponding to an

  18. [Femtosecond laser: a micromachining system for corneal surgery].

    PubMed

    Donate, D; Albert, O; Colliac, J-P; Tubelis, P; Sabatier, P; Mourou, G; Burillon, C; Pouliquen, Y; Legeais, J-M

    2004-09-01

    The authors present the diode-pumped, all-solid state, neodymium:glass femtosecond laser from the Laboratory of Ocular Biotechnology, Hotel-Dieu Hospital. We worked with a 1,065-nm wavelength infrared laser. This laser is composed of an oscillator and amplification glass matrix mixed with neodymium. Its stretching and compression system is capable of producing pulses lasting a few hundred femtoseconds. The repetition rate is adjustable, ranging from 1 to 10 kHz, and can reach energies up to 60 microJ. The delivery system was set up on an optical table, with human corneal samples fixed to an anterior chamber system, which can be moved over the X-Y-Z axis by a computer-guided translation motor with micrometric precision. We analyzed the biological effects of laser impacts in human corneal tissue, obtained from the French Eye Bank. The femtosecond laser provides automated corneal cutting with a high level of precision, which can be verified on the corneal surface regularity by scanning electron microscopy analysis. Silicon samples can also be cut and can be used for calibration testing of the laser. The set-up composed of the femtosecond laser and the described delivery system enable precise corneal cutting and offer the opportunity to study its characteristics.

  19. Formation of high-speed electron jets as the evidence for magnetic reconnection in laser-produced plasma

    NASA Astrophysics Data System (ADS)

    Huang, Kai; Huang, Can; Dong, Quanli; Lu, Quanming; Lu, San; Sheng, Zhengming; Wang, Shui; Zhang, Jie

    2017-04-01

    Experiments about the flow-driven magnetic reconnection in high-energy-density laser-produced plasmas have recently been conducted on different platforms of giant laser facilities. In this paper, we perform two-dimensional (2D) particle-in-cell simulations to study the interactions of two colliding laser-produced plasma bubbles with a self-generated toroidal magnetic field. Two cases are investigated: in one case, the two plasma bubbles have an anti-parallel magnetic field (AP-case) in the colliding region, and in the other case, the two interacting parts of the magnetic field are configured parallel to each other (P-case). In both cases, the quadrupole structure of the out-of-plane magnetic field is observed, as well as the Hall electric field and the electron energization in the colliding region. However, only in the AP-case, three well-collimated in-plane electron jets are observed. Two electron jets along the magnetic field at the edge of the plasma bubbles are formed because the electrons are trapped and accelerated by the out-of-plane electric field located between the two colliding bubbles and then move outward along the magnetic field. The high-speed electron jet in the middle of the outflow region is formed as the electrons are reflected and accelerated in the pileup region of the magnetic field, which is moving outward quickly. We demonstrate that besides the annihilation of the magnetic field in the colliding region between the two laser-produced plasma bubbles approaching each other, the three well-collimated electron jets can also be considered as the evidence for the magnetic reconnection.

  20. Development of a high speed laser scanning confocal microscope with an acquisition rate up to 200 frames per second.

    PubMed

    Choi, S; Kim, P; Boutilier, R; Kim, M Y; Lee, Y J; Lee, H

    2013-10-07

    There has been an increasing interest for observing fast biological phenomena such as cell movements in circulations and action potentials. The laser scanning confocal microscopy offers a good spatial resolution and optical sectioning ability to observe various in vivo animal models. We developed a high speed laser scanning confocal microscope capable of acquiring 512 by 512 pixel images at 200 fps (frames per second). We have incorporated a fast rotating polygonal scanning mirror with 128 facets for the X-axis scanner. In order to increase the throughput of the Y-axis scanner, we applied a bi-directional scanning method for vertical scanning. This made it possible to scan along the Y-axis two times during each scanner motion cycle. For the image acquisition, we used a custom photomultiplier tube amplifier with a broad frequency band. In addition, custom imaging software was written for the new microscope. In order to verify the acquisition speed of the developed confocal microscope, a resolution target moving at a series of constant speeds and a sedated mouse with slight movements due to heartbeats were observed. By comparing successive frames, the frame acquisition speeds were calculated.

  1. High-Speed Laser Image Analysis of Plume Angles for Pressurised Metered Dose Inhalers: The Effect of Nozzle Geometry.

    PubMed

    Chen, Yang; Young, Paul M; Murphy, Seamus; Fletcher, David F; Long, Edward; Lewis, David; Church, Tanya; Traini, Daniela

    2017-04-01

    The aim of this study is to investigate aerosol plume geometries of pressurised metered dose inhalers (pMDIs) using a high-speed laser image system with different actuator nozzle materials and designs. Actuators made from aluminium, PET and PTFE were manufactured with four different nozzle designs: cone, flat, curved cone and curved flat. Plume angles and spans generated using the designed actuator nozzles with four solution-based pMDI formulations were imaged using Oxford Lasers EnVision system and analysed using EnVision Patternate software. Reduced plume angles for all actuator materials and nozzle designs were observed with pMDI formulations containing drug with high co-solvent concentration (ethanol) due to the reduced vapour pressure. Significantly higher plume angles were observed with the PTFE flat nozzle across all formulations, which could be a result of the nozzle geometry and material's hydrophobicity. The plume geometry of pMDI aerosols can be influenced by the vapour pressure of the formulation, nozzle geometries and actuator material physiochemical properties.

  2. High speed photoacoustic imaging with fast OPO laser at 1.7 μm (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Piao, Zhonglie; Teng, Ma; Li, Jiawen; Qu, Yueqiao; Yu, Mingyue; Shung, K. Kirk; Zhou, Qifa; Kim, Chang-Seok; Chen, Zhongping

    2016-03-01

    Acute cardiovascular events are mostly due to a blood clot or thrombus induced by the sudden rupture of vulnerable atherosclerotic plaques within coronary artery walls. Based on the high optical absorption contrast of the lipid rich plaques within the vessel wall, intravascular photoacoustic (IVPA) imaging at 1.7 μm spectral band has shown promising capabilities for detecting of lipid composition, but the translation of the technology for in vivo application is limited by the slow imaging speed. In this work, we will present a high speed integrated IVPA/US imaging system with a 500 Hz optical parametric oscillator laser at 1725 nm (5 nm linewidth). A miniature catheter with 1.0 mm outer diameter was designed with a polished 200 μm multimode fiber and an ultrasound transducer with 45 MHz center frequency. Two optical illumination methods by gradient-index (GRIN) lens and ball lens are introduced and compared for higher spatial resolution. At 1725 nm, atherosclerotic rabbit abdominal aorta was imaged at two frame per second, which is more than one order of magnitude faster than previous reported IVPA imaging. Furthermore, by wide tuning range of the laser wavelength from 1680 nm to 1770 nm, spectroscopic photoacoustic analysis of lipid-mimicking phantom and an human atherosclerotic artery was performed ex vivo.

  3. Measurement of process dynamics through coaxially aligned high speed near-infrared imaging in laser powder bed fusion additive manufacturing

    NASA Astrophysics Data System (ADS)

    Fox, Jason C.; Lane, Brandon M.; Yeung, Ho

    2017-05-01

    For process stability in laser powder bed fusion (LPBF) additive manufacturing (AM), control of melt pool dimensions is imperative. In order to control melt pool dimensions in real time, sampling frequencies in excess of 10 kHz may be required, which presents a challenge for many thermal and optical monitoring systems. The National Institute of Standards and Technology (NIST) is currently developing the Additive Manufacturing Metrology Testbed (AMMT), which replicates a metal based laser powder bed fusion AM process while providing open architecture for control, sensing, and calibration sources. The system is outfitted with a coaxially aligned, near-infrared (NIR) high speed melt pool monitoring (MPM) system. Similar monitoring systems are incorporated into LPBF research testbeds, and appearing on commercial machines, but at lower available frame rates, which may limit observation of higher frequency events such as spatter or size fluctuations. This paper presents an investigation of the coaxial imaging systems of the AMMT to capture the process dynamics, and quantify the effects of dynamic fluctuations on melt pool size measurements. Analysis is carried out on a baseline experiment with no powder material added, melt pool size measurements collected in-situ are compared to ex-situ measurements, and results are discussed in terms of temporal bandwidth. Findings will show that, even at the frame rate and resolution presented, challenges in relating in-situ video signals to the ex-situ measurement analysis remain.

  4. Excimer laser micromachining of TiN films from chromium and copper sacrificial layers

    NASA Astrophysics Data System (ADS)

    Dowling, A. J.; Ghantasala, M. K.; Hayes, J. P.; Harvey, E. C.; Doyle, E. D.

    2002-10-01

    This paper presents results on the laser micromachining of TiN films. Machining performance was evaluated in terms of patterning quality and the ability to remove TiN with minimal interference with an underlying sacrificial layer. TiN was arc-deposited onto (100) silicon substrate with chromium (Cr) and copper (Cu) sacrificial layers. Films were also deposited onto bare silicon substrates under the same conditions. These films were analysed for their composition and structure using Rutherford backscattering spectroscopy and x-ray diffraction techniques. Laser micromachining was performed using a KrF excimer laser at 248 nm. The effect of fluence and number of shots on the machined features has been investigated in detail. The patterned features were examined using optical, confocal and scanning electron microscopes. The characteristics observed were analysed and compared in all three sets of samples. The results showed selective removal of TiN films from Cr and Cu sacrificial layers under different conditions. The machining of TiN from (100) silicon showed relatively poor definition of patterned features. The analysis of these results indicated that laser machining of TiN from Cr and Cu layers is best explained using the explosion mechanism of removal.

  5. Depth and surface roughness control on laser micromachined polyimide for direct-write deposition

    NASA Astrophysics Data System (ADS)

    Pratap, Bhanu; Arnold, Craig B.; Pique, Alberto

    2003-01-01

    We are examining surface characteristics of ultraviolet pulsed-laser micromachined structures in polymide as a function of the incident laser energy and the distance between subsequent laser spots in order to prepare surfaces for laser direct-write deposition of metals. Variations in the spot-to-spot translation distance provide an alternative means of average depth and roughness control when compared to fluence changes and focal distance variations. We find that the average depth is proportional to the inverse of the translation distance, while the root mean square surface roughness reaches a minimum when the translation distance is approximately equal to the full width half maximum of a single ablation mark on the surface. Conductive silver metal lines are deposited on the surface machined features demonstrating the ability to produce conductors with good adhesion over stepped structures on polyimide.

  6. Femtosecond laser micromachining of dielectric materials for biomedical applications

    NASA Astrophysics Data System (ADS)

    Farson, Dave F.; Choi, Hae Woon; Zimmerman, Burr; Steach, Jeremy K.; Chalmers, Jeffery J.; Olesik, Susan V.; Lee, L. James

    2008-03-01

    Techniques for microfluidic channel fabrication in soda-lime glass and fused quartz using femtosecond laser ablation and ablation in conjunction with polymer coating for surface roughness improvement were tested. Systematic experiments were done to characterize how process variables (laser fluence, scanning speed and focus spot overlap, and material properties) affect the machining feature size and quality. Laser fluence and focus spot overlap showed the strongest influence on channel depth and roughness. At high fluence, the surface roughness was measured to be between 395 nm and 731 nm RMS. At low fluence, roughness decreased to 100 nm-350 nm RMS and showed a greater dependence on overlap. The surface roughness of laser ablation was also dependent on the material properties. For the same laser ablation parameters, soda-lime glass surfaces were smoother than fused quartz. For some applications, especially those using quartz, smoother channels are desired. A hydroxyethyl methacrylate (HEMA) polymer coating was applied and the roughness of the coated channels was improved to 10-50 nm RMS.

  7. High-intensity fibre laser design for micro-machining applications

    NASA Astrophysics Data System (ADS)

    Ortiz-Neria, D. I.; Martinez-Piñón, F.; Hernandez-Escamilla, H.; Alvarez-Chavez, J. A.

    2010-11-01

    This work is focused on the design of a 250W high-intensity continuous-wave fibre optic laser with a 15μm spot size beam and a beam parameter product (BPP) of 1.8 for its use on Laser-assisted Cold Spray process (LCS) in the micro-machining areas. The metal-powder deposition process LCS, is a novel method based on Cold Spray technique (CS) assisted by laser technology. The LCS accelerates metal powders by the use of a high-pressure gas in order to achieve flash welding of particles over substrate. In LCS, the critical velocity of impact is lower with respect with CS while the powder particle is heated before the deposition by a laser beam. Furthermore, LCS does not heat the powder to achieve high temperatures as it happens in plasma processes. This property puts aside cooling problems which normally happen in sintered processes with high oxygen/nitrogen concentration levels. LCS will be used not only in deposition of thin layers. After careful design, proof of concept, experimental data, and prototype development, it should be feasible to perform micro-machining precise work with the use of the highintensity fibre laser presented in this work, and selective deposition of particles, in a similar way to the well-known Direct Metal Laser Sintering process (DMLS). The fibre laser consists on a large-mode area, Yb3+-doped, semi-diffraction limited, 25-m fibre laser cavity, operating in continuous wave regime. The fibre shows an arguably high slope-efficiency with no signs of roll-over. The measured M2 value is 1.8 and doping concentration of 15000ppm. It was made with a slight modification of the traditional MCVD technique. A full optical characterization will be presented.

  8. Target geometry and rigidity determines laser-induced cavitation bubble transport and nanoparticle productivity - a high-speed videography study.

    PubMed

    Kohsakowski, Sebastian; Gökce, Bilal; Tanabe, Rie; Wagener, Philipp; Plech, Anton; Ito, Yoshiro; Barcikowski, Stephan

    2016-06-28

    Laser-induced cavitation has mostly been studied in bulk liquid or at a two-dimensional wall, although target shapes for the particle synthesis may strongly affect bubble dynamics and interfere with particle productivity. We investigated the dynamics of the cavitation bubble induced by pulsed-laser ablation in liquid for different target geometries with high-speed laser microsecond videography and focus on the collapse behaviour. This method enables us observations in a high time resolution (intervals of 1 μs) and single-pulse experiments. Further, we analyzed the nanoparticle productivity, the sizes of the synthesized nanoparticles and the evolution of the bubble volume for each different target shape and geometry. For the ablation of metal (Ag, Cu, Ni) wire tips a springboard-like behaviour after the first collapse is observed which can be correlated with vertical projectile motion. Its turbulent friction in the liquid causes a very efficient transport and movement of the bubble and ablated material into the bulk liquid and prevents particle redeposition. This effect is influenced by the degree of freedom of the wire as well as the material properties and dimensions, especially the Young's modulus. The most efficient and largest bubble movement away from the wire was observed for a thin (500 μm) silver wire with velocities up to 19.8 m s(-1) and for materials with a small Young's modulus and flexural rigidity. We suggest that these observations may contribute to upscaling strategies and increase of particle yield towards large synthesis of colloids based on targets that may continuously be fed.

  9. Gated high speed optical detector

    NASA Technical Reports Server (NTRS)

    Green, S. I.; Carson, L. M.; Neal, G. W.

    1973-01-01

    The design, fabrication, and test of two gated, high speed optical detectors for use in high speed digital laser communication links are discussed. The optical detectors used a dynamic crossed field photomultiplier and electronics including dc bias and RF drive circuits, automatic remote synchronization circuits, automatic gain control circuits, and threshold detection circuits. The equipment is used to detect binary encoded signals from a mode locked neodynium laser.

  10. High speed video shooting with continuous-wave laser illumination in laboratory modeling of wind - wave interaction

    NASA Astrophysics Data System (ADS)

    Kandaurov, Alexander; Troitskaya, Yuliya; Caulliez, Guillemette; Sergeev, Daniil; Vdovin, Maxim

    2014-05-01

    Three examples of usage of high-speed video filming in investigation of wind-wave interaction in laboratory conditions is described. Experiments were carried out at the Wind - wave stratified flume of IAP RAS (length 10 m, cross section of air channel 0.4 x 0.4 m, wind velocity up to 24 m/s) and at the Large Air-Sea Interaction Facility (LASIF) - MIO/Luminy (length 40 m, cross section of air channel 3.2 x 1.6 m, wind velocity up to 10 m/s). A combination of PIV-measurements, optical measurements of water surface form and wave gages were used for detailed investigation of the characteristics of the wind flow over the water surface. The modified PIV-method is based on the use of continuous-wave (CW) laser illumination of the airflow seeded by particles and high-speed video. During the experiments on the Wind - wave stratified flume of IAP RAS Green (532 nm) CW laser with 1.5 Wt output power was used as a source for light sheet. High speed digital camera Videosprint (VS-Fast) was used for taking visualized air flow images with the frame rate 2000 Hz. Velocity air flow field was retrieved by PIV images processing with adaptive cross-correlation method on the curvilinear grid following surface wave profile. The mean wind velocity profiles were retrieved using conditional in phase averaging like in [1]. In the experiments on the LASIF more powerful Argon laser (4 Wt, CW) was used as well as high-speed camera with higher sensitivity and resolution: Optronics Camrecord CR3000x2, frame rate 3571 Hz, frame size 259×1696 px. In both series of experiments spherical 0.02 mm polyamide particles with inertial time 7 ms were used for seeding airflow. New particle seeding system based on utilization of air pressure is capable of injecting 2 g of particles per second for 1.3 - 2.4 s without flow disturbance. Used in LASIF this system provided high particle density on PIV-images. In combination with high-resolution camera it allowed us to obtain momentum fluxes directly from

  11. Femtosecond laser micromachining of Fabry-Perot cavity in fibre Bragg grating

    NASA Astrophysics Data System (ADS)

    Fiorin, Rodrigo; Cidade, Fernando N.; Adachi, Jociel L. S.; Rossi, Lucieli; de Oliveira, Valmir; Abe, Ilda; Kalinowski, Hypolito J.

    2015-09-01

    A 10 μm (length) × 75 μm (depth) open channel is fabricated in fibre Bragg gratings (FBG) by femtosecond laser micromachining. The FBG Fabry-Perot (FP) cavity formed by this complex structure has a length of 4 mm; value estimated from interference spectrum for the air open channel. Reflection spectra of FBG FP cavity as a function of the temperature shows the cavity phase change. The sensor is thermally characterized by filling polymer in the channel and subsequent UV curing; the results show a period shift of approximately 12 x10-3, value obtained of interferometer pattern for 30°C temperature range.

  12. Fiber-optic Fabry-Perot interferometer tip accelerometer fabricated by laser-micromachining

    NASA Astrophysics Data System (ADS)

    Ran, Zengling; Lu, En; Rao, Yunjiang; Ni, Min; Peng, Fei; Zeng, Dehong

    2011-05-01

    A novel fiber-optic tip accelerometer based on Fabry-Perot (F-P) interferometer is proposed and demonstrated, with potential to operate under high temperature, in this paper. Such a tip accelerometer is directed fabricated on a large cladding fiber end by using the 157nm laser-micromachining technology. With the calibration of a micro electro mechanical systems (MEMS) accelerometer, the sensitivity of such a fiber-optic F-P accelerometer is 1.764 rad/g. The minimum detective acceleration is estimated to be 20μg.

  13. In-fiber whispering-gallery-mode resonator fabricated by femtosecond laser micromachining.

    PubMed

    Shi, Leilei; Zhu, Tao; Huang, Dongmei; Liu, Min; Deng, Ming; Huang, Wei

    2015-08-15

    An in-fiber whispering-gallery-mode resonator fabricated by femtosecond laser micromachining is demonstrated. The cylinder resonator cavity is fabricated by scanning the D-fiber cladding with infrared femtosecond pulses along a cylindrical trace with a radius of 25 μm and height of 20 μm. Quality factor on the order of 10(3) is achieved by smoothing the cavity surface with an ultrasonic cleaner, which is mainly limited by the surface roughness of several hundred nanometers. Resonant characteristics and polarization dependence of the proposed resonator are also studied in detail. Our method takes a step forward in the integration of whispering-gallery-mode resonators.

  14. New applications of copper vapor lasers in micromachining

    SciTech Connect

    Chang, J.J.; Martinez, M.W.; Warner, B.E.; Dragon, E.P.; Huete, G.; Solarski, M.E.

    1994-11-09

    We have developed a copper vapor laser based micromachinig system using advanced beam quality control and precision wavefront tilting technologies. Precision microdrilling has been demonstrated through percussion drilling and trepanning using this system. With a 30-W copper vapor from running at multi-kHz pulse repetition frequency, straight parallel holes with size varying from 500 microns to less than 25 microns and with aspect ratio up to 1:40 have been consistently drilled with good surface finish on a variety of metals. Micromilling and microdrilling on ceramics using a 250-W copper vapor laser have also been demonstrated with good result. Materialographic sections of machined parts show little (submicron scale) recast layer and heat affected zone.

  15. Micromachining of transparent materials by laser ablation of organic solution

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Niino, Hiroyuki; Yabe, Akira

    2000-11-01

    Transparent materials such as fused silica, quartz, calcium fluoride, and fluorocarbon polymer were etched upon irradiation of organic solution containing pyrene with a conventional KrF excimer laser. Threshold fluence for etching was 240 mJ/cm2 for fused silica. Etch rate remarkably depended on a concentration of pyrene: higher etch rate with the increase of pyrene concentration. It means that pyrene molecules play an important role in this process. The etch rate can be easily controlled through changing a laser pulse number, a laser fluence and a concentration of solution. The mechanism for this process is discussed by cyclic multiphotonic absorption of pyrene in the excited states, thermal relaxation, and formation of super-heated solution. As the results, it is suggested that the process is based on the combination of two processes in the interface between the transparent materials and the liquid: one is a heating process by a super-heated liquid and the other is an attacking process by a high temperature and pressure vapor.

  16. Progress in fabrication of waveguide spatial light modulators via femtosecond laser micromachining

    NASA Astrophysics Data System (ADS)

    Savidis, Nickolaos; Jolly, Sundeep; Datta, Bianca; Moebius, Michael; Karydis, Thrasyvoulos; Mazur, Eric; Gershenfeld, Neil; Bove, V. Michael

    2017-02-01

    We have previously introduced a femtosecond laser micromachining-based scheme for the fabrication of anisotropic waveguides in lithium niobate for use in a guided-wave acousto-optic spatial light modulator. This spatial light modulation scheme is extensible to off-plane waveguide holography via the integration of a Bragg reflection grating. In this paper, we present femtosecond laser-based direct-write approaches for the fabrication of (1) waveguide in-coupling gratings and (2) volume Bragg reflection gratings via permanent refractive index changes within the lithium niobate substrate. In combination with metal surface-acoustic-wave transducers, these direct-write approaches allow for complete fabrication of a functional spatial light modulator via femtosecond laser direct writing.

  17. Picosecond pulsed laser ablation and micromachining of 4H-SiC wafers

    NASA Astrophysics Data System (ADS)

    Molian, Pal; Pecholt, Ben; Gupta, Saurabh

    2009-02-01

    Ultra-short pulsed laser ablation and micromachining of n-type, 4H-SiC wafer was performed using a 1552 nm wavelength, 2 ps pulse, 5 μJ pulse energy erbium-doped fiber laser with an objective of rapid etching of diaphragms for pressure sensors. Ablation rate, studied as a function of energy fluence, reached a maximum of 20 nm per pulse at 10 mJ/cm 2, which is much higher than that achievable by the femtosecond laser for the equivalent energy fluence. Ablation threshold was determined as 2 mJ/cm 2. Scanning electron microscope images supported the Coulomb explosion (CE) mechanism by revealing very fine particulates, smooth surfaces and absence of thermal effects including melt layer formation. It is hypothesized that defect-activated absorption and multiphoton absorption mechanisms gave rise to a charge density in the surface layers required for CE and enabled material expulsion in the form of nanoparticles. Trenches and holes micromachined by the picosecond laser exhibited clean and smooth edges and non-thermal ablation mode for pulse repetition rates less than 250 kHz. However carbonaceous material and recast layer were noted in the machined region when the pulse repetition rate was increased 500 kHz that could be attributed to the interaction between air plasma and micro/nanoparticles. A comparison with femtosecond pulsed lasers shows the promise that picosecond lasers are more efficient and cost effective tools for creating sensor diaphragms and via holes in 4H-SiC.

  18. Industrial grade fiber-coupled laser systems delivering ultrashort high-power pulses for micromachining

    NASA Astrophysics Data System (ADS)

    Pricking, Sebastian; Welp, Petra; Overbuschmann, Johannes; Nutsch, Sebastian; Gebs, Raphael; Fleischhaker, Robert; Kleinbauer, Jochen; Wolf, Martin; Budnicki, Aleksander; Sutter, Dirk H.; Killi, Alexander; Mielke, Michael

    2016-03-01

    We report on an industrial fiber-delivered laser system producing ultra-short pulses in the range of a few picoseconds down to a few hundred femtoseconds with high average power suitable for high-precision micromachining. The delivery fiber is a hollow-core photonic crystal fiber with a Kagomé shaped lattice and a hypocycloid core wall enabling the guiding of laser radiation over several meters with exceptionally low losses and preservation of high beam quality (M2<1.3). The mode-matching and coupling optics are integrated into the laser head providing a compact footprint without the need for external boxes. The laser head is carefully designed regarding its thermo-mechanical properties to allow a highly reliable coupling stability. The exchangeable delivery fiber is packaged using Trumpf's well established LLK-D connectors which offer a very high mechanical precision, the possibility to add water cooling, as well as full featured safety functions. The fiber is hermetically sealed and protected by a robust but flexible shield providing bend protection and break detection. We show the linear and nonlinear optical properties of the transported laser radiation and discuss its feasibility for pulse compression. Measurements are supported by simulation of pulse propagation by solving the nonlinear Schrödinger equation implementing the split-step Fourier method. In addition, mode properties are measured and confirmed by finite element method simulations. The presented industrial laser system offers the known advantages of ultra-short pulses combined with the flexibility of fiber delivery yielding a versatile tool perfectly suitable for all kinds of industrial micromachining applications.

  19. Distribution of biomolecules in porous nitrocellulose membrane pads using confocal laser scanning microscopy and high-speed cameras.

    PubMed

    Mujawar, Liyakat Hamid; Maan, Abid Aslam; Khan, Muhammad Kashif Iqbal; Norde, Willem; van Amerongen, Aart

    2013-04-02

    The main focus of our research was to study the distribution of inkjet printed biomolecules in porous nitrocellulose membrane pads of different brands. We produced microarrays of fluorophore-labeled IgG and bovine serum albumin (BSA) on FAST, Unisart, and Oncyte-Avid slides and compared the spot morphology of the inkjet printed biomolecules. The distribution of these biomolecules within the spot embedded in the nitrocellulose membrane was analyzed by confocal laser scanning microscopy in the "Z" stack mode. By applying a "concentric ring" format, the distribution profile of the fluorescence intensity in each horizontal slice was measured and represented in a graphical color-coded way. Furthermore, a one-step diagnostic antibody assay was performed with a primary antibody, double-labeled amplicons, and fluorophore-labeled streptavidin in order to study the functionality and distribution of the immune complex in the nitrocellulose membrane slides. Under the conditions applied, the spot morphology and distribution of the primary labeled biomolecules was nonhomogenous and doughnut-like on the FAST and Unisart nitrocellulose slides, whereas a better spot morphology with more homogeneously distributed biomolecules was observed on the Oncyte-Avid slide. Similar morphologies and distribution patterns were observed when the diagnostic one-step nucleic acid microarray immunoassay was performed on these nitrocellulose slides. We also investigated possible reasons for the differences in the observed spot morphology by monitoring the dynamic behavior of a liquid droplet on and in these nitrocellulose slides. Using high speed cameras, we analyzed the wettability and fluid flow dynamics of a droplet on the various nitrocellulose substrates. The spreading of the liquid droplet was comparable for the FAST and Unisart slides but different, i.e., slower, for the Oncyte-Avid slide. The results of the spreading of the droplet and the penetration behavior of the liquid in the

  20. Computer-generated volume holograms fabricated by femtosecond laser micromachining.

    PubMed

    Cai, Wenjian; Reber, Theodore J; Piestun, Rafael

    2006-06-15

    We define computer-generated volume holograms (CGVHs) as arbitrary 3D refractive index modulations designed to perform optical functions based on diffraction, scattering, and interference phenomena. CGVHs can differ dramatically from classical volume holograms in terms of coding possibilities, and from thin computer-generated holograms in terms of efficiency and selectivity. We propose an encoding technique for designing such holograms and demonstrate the concept by scanning focused femtosecond laser pulses to produce localized refractive index modifications in glass. These CGVHs show a significant increase in efficiency with thickness. Consequently, they are attractive for photonic integration with free-space and guided-wave devices, as well as for encoding spatial and temporal information.

  1. High-speed singulation of electronic packages using a frequency-doubled Nd:YAG laser in a water jet and realization of a 200-W green laser

    NASA Astrophysics Data System (ADS)

    Wagner, Frank R.; Hu, Wentao; Spiegel, Akos; Vago, Nandor; Richerzhagen, Bernold

    2003-07-01

    Each electronic chip is packaged in order to connect the integrated circuit and the printed circuit board. In consequence high-speed singulation of packages is an important step in the manufacturing process of electronic devices. The widely used technique of abrasive sawing encounters problems due to the combination of different materials used in packages such as copper and mold compound. The sawing blade rapidly blunts because of the copper adhering to the saw blade and covering the diamonds. In fact, the abrasive saw, well adapted to silicon wafer sawing, has problems to adapt to package materials. It has already been shown that the water jet guided laser can be used for efficient high quality singulation of leadframe based packages. In this technique a low-pressure water jet guides the laser beam like an optical fiber, providing efficient cooling of the cutting kerf at exactly the point that was heated during the laser pulse. We present new cutting results using a frequency doubled Nd:YAG laser with 100 W average power, and the combination setup for generating a 200 W green laser beam. The timing between the two lasers can be precisely controlled.

  2. Enhancing the humidity response time of polymer optical fiber Bragg grating by using laser micromachining.

    PubMed

    Chen, Xianfeng; Zhang, Wei; Liu, Chen; Hong, Yanhua; Webb, David J

    2015-10-05

    The humidity sensors constructed from polymer optical fiber Bragg gratings (POFBG) respond to the water content change in the fiber induced by varying environmental condition. The water content change is a diffusion process. Therefore the response time of the POFBG sensor strongly depends on the geometry and size of the fiber. In this work we investigate the use of laser micromachining of D-shaped and slotted structures to improve the response time of polymer fiber grating based humidity sensors. A significant improvement in the response time has been achieved in laser micromachined D-shaped POFBG humidity sensors. The slotted geometry allows water rapid access to the core region but this does not of itself improve response time due to the slow expansion of the bulk of the cladding. We show that by straining the slotted sensor, the expansion component can be removed resulting in the response time being determined only by the more rapid, water induced change in core refractive index. In this way the response time is reduced by a factor of 2.5.

  3. Laser projection in high-speed glottography for high-precision measurements of laryngeal dimensions and dynamics.

    PubMed

    Schuster, Maria; Lohscheller, Jörg; Kummer, Peter; Eysholdt, Ulrich; Hoppe, Ulrich

    2005-06-01

    The detection of metric dimensions of laryngeal structures yields valuable information for both clinical and research purposes. The use of a laser projection system combined with a high-speed camera system enables the derivation of absolute spatial dimensions of the larynx. Vocal fold length, vibratory amplitudes and velocity can be derived. This was shown on 13 female and 9 male larynges during phonation of a vowel at different pitches. The vocal fold length, the amplitude of oscillation and the velocity of vibration were analyzed in between pitches of 119 to 236 Hz in the male group and 181 to 555 Hz in the female group. The vocal folds' length ranged from 8.4 to 14.3 mm in the male group and from 7.7 to 15.6 mm in the female group. Corresponding amplitudes varied from 0.33 to 1.24 mm (male) and from 0.38 to 0.82 mm (female). The maximal velocity of vibration was between 0.48 and 0.85 m/s in males and between 0.47 and 1.3 m/s in females without showing significant correlation between each parameter. The described technique enables the detection of absolute spatial laryngeal dimensions of female and male subjects at different pitches. Dynamic processes such as velocity of vibration can be quantified. The detection of metric data serves to optimize biomechanical model computations and provides valuable information in diagnostics and interpretation of organic and non-organic voice disorders.

  4. A cantilever based optical fiber acoustic sensor fabricated by femtosecond laser micromachining

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Yuan, Lei; Huang, Jie; Xiao, Hai

    2016-04-01

    In this paper, we present a pure silica micro-cantilever based optical fiber sensor for acoustic wave detection. The cantilever is directly fabricated by fs laser micromachining on an optical fiber tip functioning as an inline Fabry-Perot interferometer (FPI). The applied acoustic wave pressurizes the micro-cantilever beam and the corresponding dynamic signals can be probed by the FPI. The thickness, length, and width of the micro-cantilever beam can be flexibly designed and fabricated so that the sensitivity, frequency response, and the total measurement range can be varied to fit many practical applications. Experimental results will be presented and analyzed. Due to the assembly free fabrication of the fs-laser, multiple micro-cantilever beams could be potentially fabricated in/on a single optical fiber for quasi-distributed acoustic mapping with high spatial resolution.

  5. Programmable picosecond pulse packets for micromachining with multiwatt UV fiber lasers

    NASA Astrophysics Data System (ADS)

    Alekel, Theodore; Foster, David H.; Crist, Jordan

    2009-02-01

    Nanosecond class lasers have been the mainstay of optical machining for decades, delivering pulses with high fluences (>1 J/cm2) that cause many material sets to undergo thermally-induced phase changes to cause removal of matter. While in many cases their delivery of sheer laser power has proved useful, nanosecond lasers have fallen short of addressing current micromachining requirements with respect to decreased feature sizes and more complex substrates. One main issue is the laser pulse width endures throughout the ablation process, depositing energy is deposited into plasma formation and local material heating. Plasma shielding takes place when the laser pulse energy contributes to plasma formation to a greater extent than direct material ablation processes. The result is a crude "plasma cutter" of the substrate, leaving a telltale trail of localized dross and droplet deposition. Nanosecond lasers of sufficient process speeds are typically Q-switched with repetition rates less than 200 kHz. As a result, the scribed lines are made of a sequence of "blast events" that result in a variety of undesired consequences and a limited process speed.

  6. Laser-micromachined and laminated microfluidic components for miniaturized thermal, chemical, and biological systems

    NASA Astrophysics Data System (ADS)

    Martin, Peter M.; Matson, Dean W.; Bennett, Wendy D.; Stewart, Donald C.; Lin, Yuehe

    1999-03-01

    Microchannel microfluidic components are being developed for heat transfer, chemical reactor, chemical analysis, and biological analytical applications. Specific applications include chemical sensing, DNA replication, blood analysis, capillary electrophoresis, fuel cell reactors, high temperature chemical reactors, heat pumps, combustors, and fuel processors. Two general types of component architectures have been developed and the fabrication processes defined. All involve a lamination scheme using plastic, ceramic, or metal laminates, as opposed to planar components. The first type is a stacked architecture that utilizes functionality built in each layer, with fluid flow interconnects between layers. Each layer of the laminate has specific microchannel geometry, and performs a specific function. Polymeric materials are used primarily. Fabrication processes used are laser micromachining, wet and dry etching, and coating deposition. the laminates can also be micromolded plastics. The second architecture employs laminates to form internal microchannels and interconnects. Materials include ceramic tapes and high temperature metals. Catalysts can be placed in the microchannels. Fabrication processes used are diffusion bonding, ceramic bonding and firing, photochemical etching, and electrochemical micromachining. Bonding, thus sealing, the laminates is an important issue. Process conditions have been develop to reduce distortion of the laminates and to hermetically seal the components.

  7. Fracture Forces of Dentin after Surface Treatment with High Speed Drill Compared to Er:YAG and Er,Cr:YSGG Laser Irradiation.

    PubMed

    Franzen, Rene; Kianimanesh, Nasrin; Marx, Rudolf; Ahmed, Asma; Gutknecht, Norbert

    2016-01-01

    Dental tooth restorative procedures may weaken the structural integrity of the tooth, with the possibility of leading to fracture. In this study we present findings of coronal dentin strength after different techniques of surface modification. The fracture strength of dentin beams after superficial material removal with a fine diamond bur high speed drill hand piece, Er:YAG (2.94 μm, 8 J/cm(2)), and Er,Cr:YSGG (2.78 μm, 7.8 J/cm(2)) laser irradiation slightly above the ablation threshold was measured by a four-point bending apparatus. Untreated dentin beams served as a control. A total of 58 dentin beams were manufactured from sterilized human extracted molars using the coronal part of the available dentin. Mean values of fracture strength were calculated as 82.0 ± 27.3 MPa for the control group (n = 10), 104.5 ± 26.3 MPa for high speed drill treatment (n = 10), 96.1 ± 28.1 MPa for Er,Cr:YSGG laser irradiation (n = 20), and 89.1 ± 36.3 MPa for Er:YAG laser irradiation (n = 18). Independent Student's t-tests showed no significant difference between each two groups (p > 0.05). Within the parameter settings and the limits of the experimental setup used in this study, both lasers systems as well as the high speed drill do not significantly weaken coronal dentin after surface treatment.

  8. Micromachining NiTi tubes for use in medical devices by using a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Hung, Chia-Hung; Chang, Fuh-Yu; Chang, Tien-Li; Chang, Yu-Ting; Huang, Kai-Wen; Liang, Po-Chin

    2015-03-01

    Recent growth in medical device technology has been substantially driven by developments in laser micromachining, which is a powerful fabrication technique in which nickel-titanium (Nitinol, NiTi) alloy materials that exhibit superelastic and shape memory properties are formed (e.g., self-expanding stents). In this study a NiTi tube curve surface process is proposed, involving a femtosecond laser process and a galvano-mirror scanner. The diameter of the NiTi tube was 5.116 mm, its thickness was 0.234 mm, and its length was 100 mm. The results indicated that during the machine process the ablation mechanism of the NiTi tubes was changed by altering the machining path. The path alteration enhanced the laser ablation rate from 12.3 to 26.7 μm/J. Thus the path alteration contributed to a wide kerf line, enabling the assisted air to efficiently remove the debris deposited at the bottom of the kerf during the laser ablation process. The results indicated that the NiTi tube curve process enhanced the laser ablation rate by two times and reduced the amount of energy accumulated within the materials by 50% or more. By altering the machining path using the scanning system, this process can decrease the production of heat affected zones (the accumulation of thermal energy) in medical device applications.

  9. Underwater femtosecond laser micromachining of thin nitinol tubes for medical coronary stent manufacture

    NASA Astrophysics Data System (ADS)

    Muhammad, Noorhafiza; Li, Lin

    2012-06-01

    Microprofiling of medical coronary stents has been dominated by the use of Nd:YAG lasers with pulse lengths in the range of a few milliseconds, and material removal is based on the melt ejection with a high-pressure gas. As a result, recast and heat-affected zones are produced, and various post-processing procedures are required to remove these defects. This paper reports a new approach of machining stents in submerged conditions using a 100-fs pulsed laser. A comparison is given of dry and underwater femtosecond laser micromachining techniques of nickel-titanium alloy (nitinol) typically used as the material for coronary stents. The characteristics of laser interactions with the material have been studied. A femtosecond Ti:sapphire laser system (wavelength of 800 nm, pulse duration of 100 fs, repetition rate of 1 kHz) was used to perform the cutting process. It is observed that machining under a thin water film resulted in no presence of heat-affected zone, debris, spatter or recast with fine-cut surface quality. At the optimum parameters, the results obtained with dry cutting showed nearly the same cut surface quality as with cutting under water. However, debris and recast formation still appeared on the dry cut, which is based on material vaporization. Physical processes involved during the cutting process in a thin water film, i.e. bubble formation and shock waves, are discussed.

  10. Curve micromachining on the edges of nitinol biliary stent by ultrashort pulses laser

    NASA Astrophysics Data System (ADS)

    Hung, Chia-Hung; Chang, Fuh-Yu

    2017-05-01

    In this study, a curve micromaching process on the edges of nitinol biliary stent was proposed by a femtosecond laser system with a galvano-mirror scanner. Furthermore, the outer diameter of nitinol tube was 5.116 mm, its inner diameter was 4.648 mm, and its length was 100 mm. The initial fabricated results of nitinol biliary stent represented that the edges of nitinol biliary stent were steep and squared by femtosecond laser. However, the results also indicated that if the laser movement path was precisely programmed by utilizing the unique characteristic of Gaussian beam of femtosecond laser with aligning the edges of stent, the radius of edges enhanced significantly from 9 μm to 42.5 μm. As a result, the edges of nitinol biliary stent can be successfully fabricated from squared edges to rounded-shaped edges with precise dimension, clean surface morphology, and minimal heat-affected zone remained. Hence, the nitinol biliary stent, after femtosecond laser micromachining, would not need any further post-process to remove heat-affected zone and the squared edges.

  11. Micromachining of carbon nanocomposites with Nd:YAG and Nd:YVO4 frequency-converted solid state lasers

    NASA Astrophysics Data System (ADS)

    Dosser, Larry; Hix, Ken; Hartke, Kevin; Vaia, Richard; Li, Mingwei

    2004-07-01

    Carbon nanocomposites consist of thermoset and thermoplastic materials filled with carbon nano-particles (nanotubes, bucky balls, etc.). This new and innovative group of materials offers many advantages over standard polymers such as electrical/thermal conductivity and improved structural properties. In the current study, Nd:YAG and Nd:YVO4 solid-state lasers were used to micromachine carbon nanocomposite thermoplastic materials. Experimentation was completed to compare the ability to laser micromachine carbon nanomaterial, carbon black, and unfilled polyurethane. The experimentation studied the relationship between repetition rate, travel speed, and material removal rate. The processing consisted of cutting channels into the materials using an Nd:YVO4 laser at 1064, 532, and 355 nm wavelengths. The material removal rate and groove width were quantified for all wavelengths and compared versus the experimental variables. Trials were also completed on laser machining deep channels using an Nd:YAG laser and polyetheretherketone (PEEK) filled with carbon black and carbon nanofiber. The results of the experimentation show similar material removal rates for carbon black and carbon nanofiber filled polyurethane. The PEEK material exhibited high aspect ratio channels with both carbon black and carbon nanofiber fillers. Laser micromachining of polymers whcih were previously unmachinable using infra-red has been demonstrated.

  12. Study of fiber-tip damage mechanism during Ho:YAG laser lithotripsy by high-speed camera and the Schlieren method

    NASA Astrophysics Data System (ADS)

    Zhang, Jian J.; Getzan, Grant; Xuan, Jason R.; Yu, Honggang

    2015-02-01

    Fiber-tip degradation, damage, or burn back is a common problem during the ureteroscopic laser lithotripsy procedure to treat urolithiasis. Fiber-tip burn back results in reduced transmission of laser energy, which greatly reduces the efficiency of stone comminution. In some cases, the fiber-tip degradation is so severe that the damaged fiber-tip will absorb most of the laser energy, which can cause the tip portion to be overheated and melt the cladding or jacket layers of the fiber. Though it is known that the higher the energy density (which is the ratio of the laser energy fluence over the cross section area of the fiber core), the faster the fiber-tip degradation, the damage mechanism of the fibertip is still unclear. In this study, fiber-tip degradation was investigated by visualization of shockwave, cavitation/bubble dynamics, and calculus debris ejection with a high-speed camera and the Schlieren method. A commercialized, pulsed Ho:YAG laser at 2.12 um, 273/365/550-um core fibers, and calculus phantoms (Plaster of Paris, 10x10x10 mm cube) were utilized to mimic the laser lithotripsy procedure. Laser energy induced shockwave, cavitation/bubble dynamics, and stone debris ejection were recorded by a high-speed camera with a frame rate of 10,000 to 930,000 fps. The results suggested that using a high-speed camera and the Schlieren method to visualize the shockwave provided valuable information about time-dependent acoustic energy propagation and its interaction with cavitation and calculus. Detailed investigation on acoustic energy beam shaping by fiber-tip modification and interaction between shockwave, cavitation/bubble dynamics, and calculus debris ejection will be conducted as a future study.

  13. Planar waveguide Michelson interferometer fabricated by using 157nm mask laser micromachining

    NASA Astrophysics Data System (ADS)

    Bao, Haihong; Ran, Zengling; Wu, Xuezhong; Yang, Ke; Jiang, Yuan; Rao, Yunjiang

    2015-07-01

    A Michelson interferometer is fabricated on silica planar waveguide by using the one-step technology based on 157nm mask laser micromachining. The fabrication time for one device is ~10s. Experimental results show that such an interferometer has an excellent fringe contrast of >20dB. Its temperature and refractive index (RI) responses are tested by observing the wavelength shift of the interferometric fringes, which shows linear characteristics with a thermo-coefficient of ~9.5pm/°C and a RI-coefficient of ~36.7nm/RIU, respectively. The fabrication technology may pave a new way for direct writing of planar silica waveguide devices for sensing applications with high efficiency and quality.

  14. Ferrofluid-based optofluidic switch using femtosecond laser-micromachined waveguides.

    PubMed

    Gu, Yu; Bragheri, Francesca; Valentino, Gianna; Morris, Karl; Bellini, Nicola; Osellame, Roberto

    2015-02-20

    We present a portable optofluidic switch using a ferrofluid plug in a commercially produced microfluidic chip with waveguides added via femtosecond laser micromachining (FLM). FLM enabled the one-step fabrication of highly reproducible, perfectly aligned integrated waveguides orthogonally crossing an existing microfluidic channel. In the "ON" state for each output, the ferrofluid plug is outside the intersection and input light arrives at the output with relatively small loss. In the "OFF" state, the plug is inside the intersection and the input light is absorbed. The same plug is used to turn ON and OFF several parallel waveguides with contrast ratios of 22 dB or better. In addition, the plug is driven periodically using an electromagnet combined with a permanent magnet for frequency-dependent characterization. Photodiode data show high contrast up to 50 Hz and linear frequency response up to 1 KHz.

  15. Miniature in-line photonic crystal fiber etalon fabricated by 157 nm laser micromachining.

    PubMed

    Ran, Z L; Rao, Y J; Deng, H Y; Liao, X

    2007-11-01

    A miniature in-line fiber-optic Fabry-Perot etalon is fabricated on a photonic crystal fiber (PCF) by using 157 nm laser micromachining for the first time to our knowledge. Experimental results show that such a PCF-based etalon has an excellent fringe visibility of up to approximately 26 dB due to the mirror-finish quality of the two cavity surfaces inside the PCF. This etalon can be used as an ideal sensor for precise strain measurement under high temperature of up to 800 degrees C. It can also offer some other outstanding advantages, such as fast and easy fabrication, high reproducibility, capacity of mass production, low cost, low temperature-strain cross-sensitivity, and high signal-to-noise ratio.

  16. Picosecond laser micromachining prior to FIB milling for electronic microscopy sample preparation

    NASA Astrophysics Data System (ADS)

    Sikora, Aurélien; Fares, Lahouari; Adrian, Jérôme; Goubier, Vincent; Delobbe, Anne; Corbin, Antoine; Sentis, Marc; Sarnet, Thierry

    2017-10-01

    In order to check the manufacturing quality of electronic components using electron microscopy, the area of interest must be exposed. This requires the removal of a large quantity of matter without damaging the surrounding area. This step can be accomplished using ion milling but the processing can last a few hours. In order to accelerate the preparation of the samples, picosecond laser micromachining prior to Focused Ion Beam polishing is envisioned. Laser ablation allows the fast removal of matter but induces damages around the ablated area. Therefore the process has to be optimized in order to limit the size of both the heat affected zone and induced dislocation zone. For this purpose, cavities have been engraved in silicon and in electronic components, using a linearly polarized picosecond laser (∼50 ps) at three different wavelengths (343, 515 and 1030 nm). Results showed that the cross sectional shapes and the surface topologies can be tuned by the laser fluence and the number of pulses. Clear cross sections of bumps and cavity openings, exposing multilayer interfaces, are demonstrated. The silicon removal rates, tuned by the applied energy density, have been measured. Removal rates achieved at 200 kHz were typically hundred times higher than those achieved by ion milling and the best efficiency was obtained at 343 nm.

  17. High speed multiphoton imaging

    NASA Astrophysics Data System (ADS)

    Li, Yongxiao; Brustle, Anne; Gautam, Vini; Cockburn, Ian; Gillespie, Cathy; Gaus, Katharina; Lee, Woei Ming

    2016-12-01

    Intravital multiphoton microscopy has emerged as a powerful technique to visualize cellular processes in-vivo. Real time processes revealed through live imaging provided many opportunities to capture cellular activities in living animals. The typical parameters that determine the performance of multiphoton microscopy are speed, field of view, 3D imaging and imaging depth; many of these are important to achieving data from in-vivo. Here, we provide a full exposition of the flexible polygon mirror based high speed laser scanning multiphoton imaging system, PCI-6110 card (National Instruments) and high speed analog frame grabber card (Matrox Solios eA/XA), which allows for rapid adjustments between frame rates i.e. 5 Hz to 50 Hz with 512 × 512 pixels. Furthermore, a motion correction algorithm is also used to mitigate motion artifacts. A customized control software called Pscan 1.0 is developed for the system. This is then followed by calibration of the imaging performance of the system and a series of quantitative in-vitro and in-vivo imaging in neuronal tissues and mice.

  18. Micromachined mirrors

    NASA Astrophysics Data System (ADS)

    Conant, Robert Alan

    mirrors scanning in orthogonal directions to reflect a modulated laser beam in a raster pattern. By interfacing this raster-scanning system with a computer video card, we demonstrate a full-motion video system with resolution of 41 x 52 pixels and grayscale capability. The dynamic deformation of the surface-micromachined MEMS mirrors used in this video display is shown to be the factor that limits its optical resolution. (Abstract shortened by UMI.)

  19. Ultrafast laser with an average power of 120 W at 515 nm and a highly dynamic repetition rate in the MHz range for novel applications in micromachining

    NASA Astrophysics Data System (ADS)

    Harth, F.; Piontek, M. C.; Herrmann, T.; L'huillier, J. A.

    2016-03-01

    A new generation of resonant scanners in the kHz-range shows ultra-high deflection speeds of more than 1000m/s but suffer from an inherent nonlinear mirror oscillation. If this oscillation is not compensated, a typical bitmap, written point by point, would be strongly distorted because of the decreasing spot distance at the turning point of the scanning mirror. However, this can be avoided by a dynamic adaption of the repetition rate (RR) of the ultrafast laser. Since resonant scanners are operated in the 10 kHz-range, this means that the RR has to be continuously swept up to several 10 000 times per second between e.g. 5MHz and 10 MHz. High-speed continuous adaption of the RR could also optimize laser micromachining of narrow curved geometries, where nowadays a time consuming approximation with numerous vectors is required. We present a laser system, which is capable of sweeping the RR more than 32 000 times per second between 5MHz and 10MHz at an average output power of more than 120W at 515nm with a pulse duration of about 40 ps. The laser consists of a semiconductor oscillator, a 3-stage fiber pre-amplifier, a solid state InnoSlab power amplifier and a SHG stage. We systematically analyzed the dynamic of the laser system as well as the spectral and temporal behavior of the optical pulses. Switching the repetition rate typically causes a varying pulse energy, which could affect the machining quality over one scanning line. This effect will be analyzed and discussed. Possible techniques to compensate or avoid this effect will be considered.

  20. Fracture Forces of Dentin after Surface Treatment with High Speed Drill Compared to Er:YAG and Er,Cr:YSGG Laser Irradiation

    PubMed Central

    Franzen, Rene; Kianimanesh, Nasrin; Marx, Rudolf; Ahmed, Asma; Gutknecht, Norbert

    2016-01-01

    Dental tooth restorative procedures may weaken the structural integrity of the tooth, with the possibility of leading to fracture. In this study we present findings of coronal dentin strength after different techniques of surface modification. The fracture strength of dentin beams after superficial material removal with a fine diamond bur high speed drill hand piece, Er:YAG (2.94 μm, 8 J/cm2), and Er,Cr:YSGG (2.78 μm, 7.8 J/cm2) laser irradiation slightly above the ablation threshold was measured by a four-point bending apparatus. Untreated dentin beams served as a control. A total of 58 dentin beams were manufactured from sterilized human extracted molars using the coronal part of the available dentin. Mean values of fracture strength were calculated as 82.0 ± 27.3 MPa for the control group (n = 10), 104.5 ± 26.3 MPa for high speed drill treatment (n = 10), 96.1 ± 28.1 MPa for Er,Cr:YSGG laser irradiation (n = 20), and 89.1 ± 36.3 MPa for Er:YAG laser irradiation (n = 18). Independent Student's t-tests showed no significant difference between each two groups (p > 0.05). Within the parameter settings and the limits of the experimental setup used in this study, both lasers systems as well as the high speed drill do not significantly weaken coronal dentin after surface treatment. PMID:26962473

  1. Dependence of capillary forces on relative humidity and the surface properties of femtosecond laser micromachined titanium.

    PubMed

    Lehr, Jorge; Kietzig, Anne-Marie

    2015-06-15

    Capillary forces were measured with colloidal atomic force microscopy at different levels of relative humidity on femtosecond laser micromachined titanium surfaces. After laser machining at different intensity levels, the titanium surfaces show a nanoscale ripple topology or microscopic bumpy structures. Different machining environments were chosen to influence the surface chemistry in addition to topology: while machining in pure oxygen and water resulted in surfaces consisting of TiO2, a composite surface of TiO2 and TiN was obtained after machining in pure nitrogen. All samples were subsequently exposed to pure oxygen, carbon dioxide or water, and showed different levels of wettability and capillary force. We have introduced the concept of humidity sensitivity as the relative increase of the capillary force with respect to the measured force at 0% humidity. We report that samples with a nanoscale ripple topology machined in pure oxygen exhibit the lowest level of capillary force and the lowest sensitivity towards humidity in the environment. Surfaces with low sensitivity towards changes of the relative humidity are good candidates for technical applications, where capillary forces have to be controlled. This study contributes to the development of such surfaces, to a better understanding of how capillary bridges are formed on rough surfaces and ultimately to the exploration of the relationship between surface wettability and capillary forces. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Micro-Machining Characteristics of Ceramics by Harmonics of Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Okamoto, Yasuhiro; Sakagawa, Tomokazu; Nakamura, Hikaru; Uno, Yoshiyuki

    Aluminum nitride and silicon carbide are expected as a useful material for the substrate in semiconductor industry because of their excellent properties. Precision micro-machining without crack and with little heat affected zone is required for their applications. Shorter wavelength makes it possible to remove a material with little heat affected zone because of its high photon energy. Therefore, effects of wavelength on machining characteristics of AlN and SiC in micro-drilling using Q-swithched YAG harmonics were experimentally investigated. The drilled depth increased with decreasing the wavelength. Under the reduced pressure condition, the drilled depth increased, and the better surface integrity could be obtained compared to the atmospheric pressure condition. The circumference region around the drilled hole was oxidized for all the case, and the oxidization in the case of fourth harmonic was more remarkable than that in second harmonic. In the initial stage of drilling for AlN with fundamental wavelength, the irradiated point expanded by the absorption of laser beam with increasing the number of laser pulse, and the processing was carried out by crumbling the grain due to the thermal expansion. On the other hand, the higher harmonics could make a hole at the irradiated point from the initial stage without thermal expansion.

  3. Responses of polymers to laser plasma EUV light beyond ablation threshold and micromachining

    NASA Astrophysics Data System (ADS)

    Makimura, Tetsuya; Torii, Shuichi; Okazaki, Kota; Nakamura, Daisuke; Takahashi, Akihiko; Niino, Hiroyuki; Okada, Tatsuo; Murakami, Kouichi

    2011-06-01

    We have investigated responses of PDMS, PMMA and acrylic block copolymers (BCP) to EUV light from laserproduced plasma beyond ablation thresholds and micromachining. We generated wide band EUV light around 100 eV by irradiation of Ta targets with Nd:YAG laser light. In addition, narrow band EUV light at 11 and 13 nm were generated by irradiation of solid Xe and Sn targets, respectively, with pulsed CO2 laser light. The generated EUV light was condensed onto samples, using an ellipsoidal mirror. The EUV light was incident through windows of contact masks on the samples. We found that through-holes with a diameter of 1 μm can be fabricated in PDMS sheets with thicknesses of 10 μm. PDMS sheets are ablated if they are irradiated with EUV light beyond a threshold power density, while PDMS surfaces were modified by irradiation with the narrow band EUV light at lower power densities. Effective ablation of PMMA sheets can be applied to a LIGA-like process for fabricating micro-structures of metals using the practical apparatus. Furthermore, BCP sheets were ablated to have micro-structures. Thus, we have developed a practical technique for microma chining of PMMA, PDMS and BCP sheets in a micrometer scale.

  4. High speed photography and pulsed laser holography for diagnostic investigations of mixture formation and vibration in reciprocating engines

    NASA Astrophysics Data System (ADS)

    Wiegand, H.; Wanders, K.; Mueller, J.; Steinbichler, H.

    1983-08-01

    Using high speed photography, injection and mixture formation processes were recorded and the ignition delay time was determined at full load of a reference diesel engine at 2500 rpm. Pressure was measured by a quartz pressure transducer. Pressure increase was compared with ignition delay. Using holographic interferometry, the injection jet interaction with its environment in the atmosphere was shown. In order to identify the optimum points for fixing antiknocking sensors, holographic interferometry is recommended, because of its high local resolution. For localizing noise sources, holographic recording and evaluation of the vibration modes of complete engine transmission systems under sinusoidal and operational excitation is useful.

  5. The influence of ArF excimer laser micromachining on physicochemical properties of bioresorbable poly(L-lactide)

    NASA Astrophysics Data System (ADS)

    Stepak, Bogusz D.; Antończak, Arkadiusz J.; Szustakiewicz, Konrad; Pezowicz, Celina; Abramski, Krzysztof M.

    2016-03-01

    The main advantage of laser processing is a non-contact character of material removal and high precision attainable thanks to low laser beam dimensions. This technique enables forming a complex, submillimeter geometrical shapes such as vascular stents which cannot be manufactured using traditional techniques e.g. injection moulding or mechanical treatment. In the domain of nanosecond laser sources, an ArF excimer laser appears as a good candidate for laser micromachining of bioresorbable polymers such as poly(L-lactide). Due to long pulse duration, however, there is a risk of heat diffusion and accumulation in the material. In addition, due to short wavelength (193 nm) photochemical process can modify the chemical composition of ablated surfaces. The motivation for this research was to evaluate the influence of laser micromachining on physicochemical properties of poly(L-lactide). We performed calorimetric analysis of laser machined samples by using differential scanning calorimetry (DSC). It allowed us to find the optimal process parameters for heat affected zone (HAZ) reduction. The chemical composition of the ablated surface was investigated by FTIR in attenuated total reflectance (ATR) mode.

  6. Auto-ignition and flame stabilization of pulsed methane jets in a hot vitiated coflow studied with high-speed laser and imaging techniques

    NASA Astrophysics Data System (ADS)

    Arndt, C. M.; Gounder, J. D.; Meier, W.; Aigner, M.

    2012-08-01

    The auto-ignition of a pulsed methane jet issuing into a laminar coflow of hot exhaust products of a lean premixed hydrogen/air flat flame was examined using high-speed laser and optical measurement techniques with frame rates of 5 kHz or more. OH* chemiluminescence was used to determine the downstream location of the first auto-ignition kernel as well as the stabilization height of the steady-state lifted jet flame. OH planar laser-induced fluorescence (PLIF) was used to determine further details of the auto-ignition with a higher spatial resolution. Simultaneous imaging of broadband luminosity from a viewing angle perpendicular to the OH* chemiluminescence was applied, to three-dimensionally reconstruct the ignition kernel location in space and to determine whether the first occurrence of the kernel was within or beyond the PLIF laser sheet. The development and expansion of the jet was characterized by high-speed Schlieren imaging. Statistics have been compiled for both the ignition time as well as the downstream location of the first auto-ignition kernel and the stabilization height of the steady-state lifted jet flame. From the PLIF images it was found that auto-ignition tended to occur at the interface between bulges of the inflowing jet and the coflow. For steady-state conditions, auto-ignition kernels were observed frequently below the flame base, emphasizing that the lifted jet flame is stabilized by auto-ignition.

  7. A high speed three-dimensional spectral domain optical coherence tomography with <2 μm axial resolution using wide bandwidth femtosecond mode-locked laser

    NASA Astrophysics Data System (ADS)

    Kuroda, Hiroto; Baba, Motoyoshi; Suzuki, Masayuki; Yoneya, Shin

    2013-06-01

    We have developed an ultra-high-resolution optical coherence tomography (OCT) equipment, using a 200 nm bandwidth spectrometer and a mode-locked femtosecond laser. We have characterized this OCT, obtaining high spatial resolution in the axial direction of less than 2 μm in air via single scanning, within only 20 ms. This corresponds to an ultra-high resolution of less than 1.3 μm for measurements at the fundus retina. High resolution and high speed imaging enables us to selectively obtain a clear three dimensional (3D) lamina cribrosa itself from a 3D optic disc (OD) image in vivo.

  8. High speed handpieces

    PubMed Central

    Bhandary, Nayan; Desai, Asavari; Shetty, Y Bharath

    2014-01-01

    High speed instruments are versatile instruments used by clinicians of all specialties of dentistry. It is important for clinicians to understand the types of high speed handpieces available and the mechanism of working. The centers for disease control and prevention have issued guidelines time and again for disinfection and sterilization of high speed handpieces. This article presents the recent developments in the design of the high speed handpieces. With a view to prevent hospital associated infections significant importance has been given to disinfection, sterilization & maintenance of high speed handpieces. How to cite the article: Bhandary N, Desai A, Shetty YB. High speed handpieces. J Int Oral Health 2014;6(1):130-2. PMID:24653618

  9. High speed holographic cine-recorder

    NASA Astrophysics Data System (ADS)

    Snyder, Donald; Watts, David; Gordon, Joseph; Lysogorski, Charles; Powers, Aaron; Perry, John; Chenette, Eugene; Hudson, Roger; Young, Raymond

    2005-08-01

    Air Force Research Laboratory and North Dancer Labs researchers have completed the initial development and transition to operational use of a high-speed holographic movie system. This paper documents the first fully operational use of a novel and unique experimental capability for high-speed holographic movies and high-speed cinema interferometry. In this paper we document the initial experiments that were performed with the High Speed Holographic Recorder (HSHR) at the Munitions Directorate, Air Force Research Laboratory Site at Eglin, AFB, Florida. These experiments were performed to assess the possibilities for high-speed cine-laser holography combined with high-speed videography to document the formation and propagation of plumes of materials created by impact of high-speed projectiles. This paper details the development of the experimental procedures and initial results of this new tool. After successful integration and testing the system was delivered to Arnold Engineering Development Center.

  10. High-speed concatenation of frequency ramps using sampled grating distributed Bragg reflector laser diode sources for OCT resolution enhancement

    NASA Astrophysics Data System (ADS)

    George, Brandon; Derickson, Dennis

    2010-02-01

    Wavelength tunable sampled grating distributed Bragg reflector (SG-DBR) lasers used for telecommunications applications have previously demonstrated the ability for linear frequency ramps covering the entire tuning range of the laser at 100 kHz repetition rates1. An individual SG-DBR laser has a typical tuning range of 50 nm. The InGaAs/InP material system often used with SG-DBR lasers allows for design variations that cover the 1250 to 1650 nm wavelength range. This paper addresses the possibility of concatenating the outputs of tunable SGDBR lasers covering adjacent wavelength ranges for enhancing the resolution of OCT measurements. This laser concatenation method is demonstrated by combining the 1525 nm to 1575 nm wavelength range of a "C Band" SG-DBR laser with the 1570nm to 1620 nm wavelength coverage of an "L-Band" SG-DBR laser. Measurements show that SGDBR lasers can be concatenated with a transition switching time of less than 50 ns with undesired leakage signals attenuated by 50 dB.

  11. Micromachined microscanners for optical scanning

    NASA Astrophysics Data System (ADS)

    Kiang, Meng-Hsiung; Solgaard, Olav; Muller, Richard S.; Lau, Kam Y.

    1997-04-01

    We present the design and fabrication of surface- micromachined electrostatic-comb driven microscanners that have high angular precision over a large scan angle. When used as resonant scanners, these mirrors have fast scan rates with very low operating power. We use polysilicon microhinges, which allow the micromirrors to be lifted out of the plane of the substrate after processing is completed, to create high-aspect-ratio optical surfaces with dimensions in the hundreds of micrometers s while taking advantage of the planar surface-micromachining processing technology. Microscanners that are capable of high-speed scanning over large scan angles with high precision have been fabricated. Application of these actuated micromirrors in laser barcode scanning and optical-fiber switches have been demonstrated. These single-mirror scanners can be combined to form more complicated microscanners such as a two-mirror, two-axis raster scanner that have a wide range of applications in areas such as medicine, displays, printing, data storage, and communications.

  12. Influence of particle drag coefficient on particle motion in high-speed flow with typical laser velocimeter applications

    NASA Technical Reports Server (NTRS)

    Walsh, M. J.

    1976-01-01

    The effect of using different particle drag coefficient C sub D equations for computing the velocity of seeded particles in high-speed gas flows was investigated. The C sub D equations investigated included the Stokes equation, a second incompressible equation valid for higher relative Reynolds numbers, and six equations that account for the effects of compressibility together with the effects of relative Reynolds numbers greater than one. The flows investigated were center-line nozzle flows, normal shocks, and oblique shocks for free-stream Mach numbers of 1.6 to 6 and stagnation pressures of 1 and 3.4 atmospheres. The net result was empirical C sub D equation based on the latest sphere C sub D data for the low relative Mach number and Reynolds number conditions that are encountered in supersonic flows.

  13. Vertical Emitting, Ring Geometry, Ultra-Low Threshold and Ultra-High Speed Quantum Well Lasers for Optical Interconnect

    DTIC Science & Technology

    1990-02-01

    substrates were fabricated to simulate the conditions to be expected in laser fabrication . Several methods of preparation for grating definition were...is evident, its height is the upper limited considered for laser fabrication . The left hand side of the figure shows the fabricated grating, its

  14. A linearly frequency-swept high-speed-rate multi-wavelength laser for optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Wang, Qiyu; Wang, Zhaoying; Yuan, Quan; Ma, Rui; Du, Tao; Yang, Tianxin

    2017-02-01

    We proposed and demonstrated a linearly frequency-swept multi-wavelength laser source for optical coherence tomography (OCT) eliminating the need of wavenumber space resampling in the postprocessing progress. The source consists of a multi-wavelength fiber laser source (MFS) and an optical sweeping loop. In this novel laser source, an equally spaced multi-wavelength laser is swept simultaneously by a certain step each time in the frequency domain in the optical sweeping loop. The sweeping step is determined by radio frequency (RF) signal which can be precisely controlled. Thus the sweeping behavior strictly maintains a linear relationship between time and frequency. We experimentally achieved linear time-frequency sweeping at a sweeping rate of 400 kHz with our laser source.

  15. Improved hollow-core photonic crystal fiber design for delivery of nanosecond pulses in laser micromachining applications.

    PubMed

    Shephard, Jonathan D; Couny, Francois; Russell, Phillip St J; Jones, Julian D C; Knight, Jonathan C; Hand, Duncan P

    2005-07-20

    We report the delivery of high-energy nanosecond pulses (approximately 65 ns pulse width) from a high-repetition-rate (up to 100 kHz) Q-switched Nd:YAG laser through the fundamental mode of a hollow-core photonic crystal fiber (HC-PCF) at 1064 nm. The guided mode in the HC-PCF has a low overlap with the glass, allowing delivery of pulses with energies above those attainable with other fibers. Energies greater than 0.5 mJ were delivered in a single spatial mode through the hollow-core fiber, providing the pulse energy and high beam quality required for micromachining of metals. Practical micromachining of a metal sheet by fiber delivery has been demonstrated.

  16. Laser micromachined isoelectric focusing devices on polymer substrate for electrospray mass spectrometry

    NASA Astrophysics Data System (ADS)

    Lin, Yuehe; Wen, Jenny; Fan, Xiang; Matson, Dean W.; Smith, Richard D.

    1999-08-01

    A microfabricated device for isoelectric focusing (IEF) incorporating an optimized electrospray ionization (ESI) tip was constructed on polycarbonate plates using a laser micromachining technique. The separation channels on an IEF chip were 16 cm long, 50 micrometers wide and 30 micrometers deep. Electrical potentials used for IEF focusing and electrospray were applied through platinum electrodes placed in the buffer reservoirs, and which were isolated from the separation channel by molecular porous membranes. On-line ESI produced directly from a sharp `tip' on the microchip was evaluated. The results indicate that this design can produce a stable electrospray that is further improved and made more flexible with the assistance of sheath gas and sheath liquid. Error analysis of the spectral data shows that the standard deviation in signal intensity for an analyte peak was less than approximately 5% over 3 hours. The production of stable electrosprays directly from microchip IEF devices represents a step towards easily- fabricated microanalytical devices. IEF separations of protein mixtures were demonstrated for uncoated polycarbonate microchips. On-line IEF/ESI-MS was demonstrated using the microfabricated chip with an ion-trap ESI mass spectrometer for characterization of protein mixtures.

  17. Formation of porous networks on polymeric surfaces by femtosecond laser micromachining

    NASA Astrophysics Data System (ADS)

    Assaf, Youssef; Kietzig, Anne-Marie

    2017-02-01

    In this study, porous network structures were successfully created on various polymer surfaces by femtosecond laser micromachining. Six different polymers (poly(tetrafluoroethylene) (PTFE), poly(methyl methacrylate) (PMMA), high density poly(ethylene) (HDPE), poly(lactic acid) (PLA), poly(carbonate) (PC), and poly(ethylene terephthalate) (PET)) were machined at different fluences and pulse numbers, and the resulting structures were identified and compared by lacunarity analysis. At low fluence and pulse numbers, porous networks were confirmed to form on all materials except PLA. Furthermore, all networks except for PMMA were shown to bundle up at high fluence and pulse numbers. In the case of PC, a complete breakdown of the structure at such conditions was observed. Operation slightly above threshold fluence and at low pulse numbers is therefore recommended for porous network formation. Finally, the thickness over which these structures formed was measured and compared to two intrinsic material dependent parameters: the single pulse threshold fluence and the incubation coefficient. Results indicate that a lower threshold fluence at operating conditions favors material removal over structure formation and is hence detrimental to porous network formation. Favorable machining conditions and material-dependent parameters for the formation of porous networks on polymer surfaces have thus been identified.

  18. All-laser-micromachining of ridge waveguides in LiNbO3 crystal for mid-infrared band applications.

    PubMed

    Li, Lingqi; Nie, Weijie; Li, Ziqi; Lu, Qingming; Romero, Carolina; Vázquez de Aldana, Javier R; Chen, Feng

    2017-08-01

    The femtosecond laser micromachining of transparent optical materials offers a powerful and feasible solution to fabricate versatile photonic components towards diverse applications. In this work, we report on a new design and fabrication of ridge waveguides in LiNbO3 crystal operating at the mid-infrared (MIR) band by all-femtosecond-laser microfabrication. The ridges consist of laser-ablated sidewalls and laser-written bottom low-index cladding tracks, which are constructed for horizontal and longitudinal light confinement, respectively. The ridge waveguides are found to support good guidance at wavelength of 4 μm. By applying this configuration, Y-branch waveguiding structures (1 × 2 beam splitters) have been produced, which reach splitting ratios of ∼1:1 at 4 μm. This work paves a simple and feasible way to construct novel ridge waveguide devices in dielectrics through all-femtosecond-laser micro-processing.

  19. High-speed Intravascular Photoacoustic Imaging of Lipid-laden Atherosclerotic Plaque Enabled by a 2-kHz Barium Nitrite Raman Laser

    PubMed Central

    Wang, Pu; Ma, Teng; Slipchenko, Mikhail N.; Liang, Shanshan; Hui, Jie; Shung, K. Kirk; Roy, Sukesh; Sturek, Michael; Zhou, Qifa; Chen, Zhongping; Cheng, Ji-Xin

    2014-01-01

    Lipid deposition inside the arterial wall is a key indicator of plaque vulnerability. An intravascular photoacoustic (IVPA) catheter is considered a promising device for quantifying the amount of lipid inside the arterial wall. Thus far, IVPA systems suffered from slow imaging speed (~50 s per frame) due to the lack of a suitable laser source for high-speed excitation of molecular overtone vibrations. Here, we report an improvement in IVPA imaging speed by two orders of magnitude, to 1.0 s per frame, enabled by a custom-built, 2-kHz master oscillator power amplifier (MOPA)-pumped, barium nitrite [Ba(NO3)2] Raman laser. This advancement narrows the gap in translating the IVPA technology to the clinical setting. PMID:25366991

  20. Digital Photonic Production of Micro Structures in Glass by In-Volume Selective Laser-Induced Etching using a High Speed Micro Scanner

    NASA Astrophysics Data System (ADS)

    Gottmann, Jens; Hermans, Martin; Ortmann, Jürgen

    Digital photonic production of 3D microfluidic devices and assembled micro mechanics inside fused silica glass is carried out using ISLE directly from digital CAD data. To exploit the potential productivity of new high average power fs-lasers >150 W a modular high speed scanning system has been developed. Acousto-optical beam deflection, galvo-scanners and translation stages are controlled by CAM software. Using a lens with 10 mm focal length a focus radius of 1 μm is scanned with a velocity of 12 m/s on 400 μm track radius enabling the up-scaling of the ISLE- process using fs-laser radiation with up to 30 W.

  1. High-speed intravascular photoacoustic imaging of lipid-laden atherosclerotic plaque enabled by a 2-kHz barium nitrite raman laser.

    PubMed

    Wang, Pu; Ma, Teng; Slipchenko, Mikhail N; Liang, Shanshan; Hui, Jie; Shung, K Kirk; Roy, Sukesh; Sturek, Michael; Zhou, Qifa; Chen, Zhongping; Cheng, Ji-Xin

    2014-11-04

    Lipid deposition inside the arterial wall is a key indicator of plaque vulnerability. An intravascular photoacoustic (IVPA) catheter is considered a promising device for quantifying the amount of lipid inside the arterial wall. Thus far, IVPA systems suffered from slow imaging speed (~50 s per frame) due to the lack of a suitable laser source for high-speed excitation of molecular overtone vibrations. Here, we report an improvement in IVPA imaging speed by two orders of magnitude, to 1.0 s per frame, enabled by a custom-built, 2-kHz master oscillator power amplifier (MOPA)-pumped, barium nitrite [Ba(NO3)2] Raman laser. This advancement narrows the gap in translating the IVPA technology to the clinical setting.

  2. Minimisation of the thermal load of the ablation in high-speed laser corneal refractive surgery: the 'intelligent thermal effect control' of the AMARIS platform

    NASA Astrophysics Data System (ADS)

    Brunsmann, Ulrich; Sauer, Udo; Dressler, Katharina; Triefenbach, Nico; Arba Mosquera, Samuel

    2010-03-01

    The purpose of this work was to evaluate the extent that minimisation of the thermal load of the ablation in high-speed laser corneal refractive surgery is possible. To do this, thermal load from ablations onto flat PMMA plates was recorded with an infrared thermal camera and analysed for different flying-spot sorting algorithms (from pure randomised to 36 Hz local frequency) using a 500 Hz laser system with a fluence of 500 mJ/cm2, and aspheric ablation profiles. Each ablation configuration was repeated three times. Thermal load valid for corneal ablations was modelled based upon the results from ablations onto flat PMMA plates. It was found that the thermal load of ablations onto flat PMMA plates declines steadily when the allowed local frequency decreases or when the diameter of the blocked area increases. With this laser system, a local frequency of 39 Hz dynamically controlled over a diameter of 3.865 mm seems to be optimal for avoiding corneal collagen denaturation with minimum compromise on treatment duration. Peak temperature changes of 48°C in PMMA (16°C equivalent cornea) using pure randomised flying-spot sorting algorithms were reduced to 27°C in PMMA (9°C equivalent cornea) using 36 Hz local frequency over a blocked diameter of 4.25 mm. Average temperature changes of 15°C in PMMA (5°C equivalent cornea) using pure randomised flying-spot sorting algorithms were reduced to 7°C in PMMA (2°C equivalent cornea) using 36 Hz local frequency over a blocked diameter of 4.25 mm. Hence, minimisation of the thermal load of the ablation in high-speed laser corneal refractive surgery seems feasible using 'Intelligent Thermal Effect Control'. Clinical evaluations of human eyes are needed to confirm the preliminary simulated results presented here.

  3. Novel 1.3-micron high-speed directly modulated semiconductor laser device designs and the development of wafer bonding technology for compliant-substrate fabrication

    NASA Astrophysics Data System (ADS)

    Greenberg, Joseph

    2000-10-01

    High speed optical sources at 1.3 mum are required to drive the fiber optic infrastructure around the world. Of the three components that make up an optical link, these sources limit the overall data transmission capacity of these networks. The importance of operating at 1.3 mum, has led device engineers to rely on InP-based devices, though inferior in many ways to devices based on GaAs. This work seeks to develop new device designs to improve the directly modulated bandwidths of 1.3 mum lasers. Elevated temperatures degrade the DC and high speed performance of semiconductor lasers. InP-based devices are especially susceptible to temperature variations. Lasers were flip chip bonded to diamond heat sinks to improve heat removal from these devices. Although dramatic improvements were seen in their DC performance, the lasers' high frequency response did not improve. Other factors such, as carrier heating, likely limited the performance of these devices. Device designs on GaAs emitting at 1.3 mum were sought as a replacement for the troublesome InP devices. Laser structures employing ordered quantum wells on GaAs (111) substrates have been proposed. Theoretical calculations indicate that 1.3 mum emission should be achievable, and 1.55 mum emission may be possible. Experimental evidence from devices based on GaAs (111) indicates that such lasers should outperform their InP-based counterparts. Lasers grown on InGaAs-like substrates, either bulk ternary or compliant substrates, are promising candidates for improving 1.3 mum device performance. In anticipation of availability of such substrates, a toolkit for designing InxGa1--xAs quantum well lasers on InyGa 1--yAs substrates has been developed. The choice of well and substrate compositions, well width and desired percentage strain combinations emitting at 1.3 mum can be made using a few simple graphs. An analytical valence band model has been employed to qualitatively test competing device designs. Twist bonded compliant

  4. Advanced micromachining combining nanosecond lasers with water jet-guided laser technology

    NASA Astrophysics Data System (ADS)

    Pauchard, A.; Lee, K.; Vago, N.; Pavius, M.; Obi, S.

    2009-02-01

    This paper presents the first scribing results obtained by combining a short-pulse 10ns green laser with the water jet-guided laser technology. A number of high-potential applications are presented, from the grooving of low-k silicon wafers, the scribing of metallic and amorphous Si layers of thin film solar cells, the grooving of SiC wafers, and dot marking of Si wafers. The combination of a short pulse laser beam with the water jet-guided laser technology offers a new industry-proven alternative for grooving and scribing processes, providing superior speed and quality compared to legacy laser technologies.

  5. Micromachined spinneret

    SciTech Connect

    Okandan, Murat; Galambos, Paul

    2007-11-06

    A micromachined spinneret is disclosed which has one or more orifices through which a fiber-forming material can be extruded to form a fiber. Each orifice is surrounded by a concentric annular orifice which allows the fiber to be temporarily or permanently coated with a co-extrudable material. The micromachined spinneret can be formed by a combination of surface and bulk micromachining.

  6. Development of a high speed wideband frequency tunable infrared laser source for real time wind turbine array sensing applications

    NASA Astrophysics Data System (ADS)

    Mitchell, Philip; Janssen, Adrian; Partov Poor, Bahar

    2011-05-01

    This paper reports the development of an infra-red circa 193THz (~1.5μm) frequency tunable laser source selected and evaluated for photonic environment sensing systems. LIDAR (LIght Detection And Ranging) offers a method of remote wind speed measurement. Widespread deployment of the technique has been limited by the expense and complexity of LIDAR systems. However development of systems based on optical fiber and photonic components from the telecommunications industry promises improvements in cost, compactness, and reliability, so that it becomes viable to consider deployment of such systems on large wind turbines for the advance detection of fluctuations of wind speed. A monolithic multi-section laser, originally designed as a tunable source for telecommunications applications, has been modified and re-evaluated as a source for sensing applications, based on the technique of coherent laser radar (CLR), and coherent doppler LIDAR (CDL). A tunable frequency optical source should fulfil specific technical criteria to fulfil the applications requirements; speed of frequency selection, absolute accuracy of emitted frequency, spectral purity, and stability. Custom electronics and firmware were developed to realise an improvement in frequency switching speed by a factor of 10 relative to equivalent commercially available telecoms (DBR) sources, satisfying the target application requirements. An overview of the sensing architecture is presented, a detailed description of the fast tuning process described, including the custom hardware and firmware, and specifically the laser energising sequence. The results of the laser module are then presented with detailed consideration of the target application.

  7. High-speed cutting of thin materials with a Q-switched laser in a water-jet versus conventional laser cutting with a free running laser

    NASA Astrophysics Data System (ADS)

    Wagner, Frank R.; Boillat, Christophe; Buchilly, Jean-Marie; Spiegel, Akos; Vago, Nandor; Richerzhagen, Bernold

    2003-07-01

    Cutting of thin material, c.f. stencils, stents and thin wafers, is an important market for laser machining. Traditionally this task is performed using flash-lamp pumped, free-running Nd:YAG lasers. Using the water-jet guided laser technology, we experienced that the use of Q-switched lasers leads to superior results while cutting a variety of thin materials. In this technique, the laser is conducted to the work piece by total internal reflection in a thin stable water-jet, comparable to the core of an optical fiber. Utilizing this system, we obtain burr-free, slightly tapered cuts at the same speed as the classical laser cutting and without distinguishable heat affected zone. The main difference is, except the water-jet usage, the pulse duration which is approximately 400 ns instead of 20 to 200 μs in the case of free running lasers. Up to 40'000 high quality apertures per hour can be achieved in stencil mask cutting with the new system. We will compare qualitatively the two possibilities: conventional laser cutting with free-running lasers and water-jet guided laser cutting with Q-switched lasers. The results will be discussed in terms of the different physical effects involved in the material removal upon both methods. In particular the importance of molten material expulsion by the water-jet will be pointed out and compared to the action of the assist-gas. The mentioned effects show that the combination of short pulse laser and water-jet will be beneficial for the production of a wide range of precision parts.

  8. High speed fabrication of absorbance-enhanced micro-nanostructures on nickel surface using hundred-nanosecond pulsed laser

    NASA Astrophysics Data System (ADS)

    Fu, Jinxiang; Zhang, Jingyuan; Liang, Hao; Wang, Yibo; Zhang, Zhiyan; Liu, Yannan; Lin, Xuechun

    2017-01-01

    We report the generation of micro-nanostructures on nickel surface using a pulsed laser with pulse duration of 100/200 ns. The blacken nickel, which is covered with dense broccoli-like clusters having strong light trapping capacity covering broad spectrum (200-2000 nm), can be produced at a high laser scanning speed up to 100 mm/s. The absorbance of the blacken nickel can be over 98% in the UV, more than 97% in the visible, and over 90% in the near IR. In addition, by treating the nickel surface with two crossing scans of the laser, highly organized and shape-controllable periodic arrays of hump-craters can be fabricated.

  9. All-diode-pumped quasi-continuous burst-mode laser for extended high-speed planar imaging.

    PubMed

    Slipchenko, Mikhail N; Miller, Joseph D; Roy, Sukesh; Gord, James R; Meyer, Terrence R

    2013-01-14

    An all-diode-pumped, multistage Nd:YAG amplifier is investigated as a means of extending the duration of high-power, burst-mode laser pulse sequences to an unprecedented 30 ms or more. The laser generates 120 mJ per pulse at 1064.3 nm with a repetition rate of 10 kHz, which is sufficient for a wide range of planar laser diagnostics based on fluorescence, Raman scattering, and Rayleigh scattering, among others. The utility of the technique is evaluated for image sequences of formaldehyde fluorescence in a lifted methane-air diffusion flame. The advantages and limitations of diode pumping are discussed, along with long-pulse diode-bar performance characteristics to guide future designs.

  10. Predictive modeling, simulation, and optimization of laser processing techniques: UV nanosecond-pulsed laser micromachining of polymers and selective laser melting of powder metals

    NASA Astrophysics Data System (ADS)

    Criales Escobar, Luis Ernesto

    One of the most frequently evolving areas of research is the utilization of lasers for micro-manufacturing and additive manufacturing purposes. The use of laser beam as a tool for manufacturing arises from the need for flexible and rapid manufacturing at a low-to-mid cost. Laser micro-machining provides an advantage over mechanical micro-machining due to the faster production times of large batch sizes and the high costs associated with specific tools. Laser based additive manufacturing enables processing of powder metals for direct and rapid fabrication of products. Therefore, laser processing can be viewed as a fast, flexible, and cost-effective approach compared to traditional manufacturing processes. Two types of laser processing techniques are studied: laser ablation of polymers for micro-channel fabrication and selective laser melting of metal powders. Initially, a feasibility study for laser-based micro-channel fabrication of poly(dimethylsiloxane) (PDMS) via experimentation is presented. In particular, the effectiveness of utilizing a nanosecond-pulsed laser as the energy source for laser ablation is studied. The results are analyzed statistically and a relationship between process parameters and micro-channel dimensions is established. Additionally, a process model is introduced for predicting channel depth. Model outputs are compared and analyzed to experimental results. The second part of this research focuses on a physics-based FEM approach for predicting the temperature profile and melt pool geometry in selective laser melting (SLM) of metal powders. Temperature profiles are calculated for a moving laser heat source to understand the temperature rise due to heating during SLM. Based on the predicted temperature distributions, melt pool geometry, i.e. the locations at which melting of the powder material occurs, is determined. Simulation results are compared against data obtained from experimental Inconel 625 test coupons fabricated at the National

  11. The laser micro-machining system for diamond anvil cell experiments and general precision machining applications at the High Pressure Collaborative Access Team

    SciTech Connect

    Hrubiak, Rostislav; Sinogeikin, Stanislav; Rod, Eric; Shen, Guoyin

    2015-07-15

    We have designed and constructed a new system for micro-machining parts and sample assemblies used for diamond anvil cells and general user operations at the High Pressure Collaborative Access Team, sector 16 of the Advanced Photon Source. The new micro-machining system uses a pulsed laser of 400 ps pulse duration, ablating various materials without thermal melting, thus leaving a clean edge. With optics designed for a tight focus, the system can machine holes any size larger than 3 μm in diameter. Unlike a standard electrical discharge machining drill, the new laser system allows micro-machining of non-conductive materials such as: amorphous boron and silicon carbide gaskets, diamond, oxides, and other materials including organic materials such as polyimide films (i.e., Kapton). An important feature of the new system is the use of gas-tight or gas-flow environmental chambers which allow the laser micro-machining to be done in a controlled (e.g., inert gas) atmosphere to prevent oxidation and other chemical reactions in air sensitive materials. The gas-tight workpiece enclosure is also useful for machining materials with known health risks (e.g., beryllium). Specialized control software with a graphical interface enables micro-machining of custom 2D and 3D shapes. The laser-machining system was designed in a Class 1 laser enclosure, i.e., it includes laser safety interlocks and computer controls and allows for routine operation. Though initially designed mainly for machining of the diamond anvil cell gaskets, the laser-machining system has since found many other micro-machining applications, several of which are presented here.

  12. The laser micro-machining system for diamond anvil cell experiments and general precision machining applications at the High Pressure Collaborative Access Team

    NASA Astrophysics Data System (ADS)

    Hrubiak, Rostislav; Sinogeikin, Stanislav; Rod, Eric; Shen, Guoyin

    2015-07-01

    We have designed and constructed a new system for micro-machining parts and sample assemblies used for diamond anvil cells and general user operations at the High Pressure Collaborative Access Team, sector 16 of the Advanced Photon Source. The new micro-machining system uses a pulsed laser of 400 ps pulse duration, ablating various materials without thermal melting, thus leaving a clean edge. With optics designed for a tight focus, the system can machine holes any size larger than 3 μm in diameter. Unlike a standard electrical discharge machining drill, the new laser system allows micro-machining of non-conductive materials such as: amorphous boron and silicon carbide gaskets, diamond, oxides, and other materials including organic materials such as polyimide films (i.e., Kapton). An important feature of the new system is the use of gas-tight or gas-flow environmental chambers which allow the laser micro-machining to be done in a controlled (e.g., inert gas) atmosphere to prevent oxidation and other chemical reactions in air sensitive materials. The gas-tight workpiece enclosure is also useful for machining materials with known health risks (e.g., beryllium). Specialized control software with a graphical interface enables micro-machining of custom 2D and 3D shapes. The laser-machining system was designed in a Class 1 laser enclosure, i.e., it includes laser safety interlocks and computer controls and allows for routine operation. Though initially designed mainly for machining of the diamond anvil cell gaskets, the laser-machining system has since found many other micro-machining applications, several of which are presented here.

  13. The laser micro-machining system for diamond anvil cell experiments and general precision machining applications at the High Pressure Collaborative Access Team.

    PubMed

    Hrubiak, Rostislav; Sinogeikin, Stanislav; Rod, Eric; Shen, Guoyin

    2015-07-01

    We have designed and constructed a new system for micro-machining parts and sample assemblies used for diamond anvil cells and general user operations at the High Pressure Collaborative Access Team, sector 16 of the Advanced Photon Source. The new micro-machining system uses a pulsed laser of 400 ps pulse duration, ablating various materials without thermal melting, thus leaving a clean edge. With optics designed for a tight focus, the system can machine holes any size larger than 3 μm in diameter. Unlike a standard electrical discharge machining drill, the new laser system allows micro-machining of non-conductive materials such as: amorphous boron and silicon carbide gaskets, diamond, oxides, and other materials including organic materials such as polyimide films (i.e., Kapton). An important feature of the new system is the use of gas-tight or gas-flow environmental chambers which allow the laser micro-machining to be done in a controlled (e.g., inert gas) atmosphere to prevent oxidation and other chemical reactions in air sensitive materials. The gas-tight workpiece enclosure is also useful for machining materials with known health risks (e.g., beryllium). Specialized control software with a graphical interface enables micro-machining of custom 2D and 3D shapes. The laser-machining system was designed in a Class 1 laser enclosure, i.e., it includes laser safety interlocks and computer controls and allows for routine operation. Though initially designed mainly for machining of the diamond anvil cell gaskets, the laser-machining system has since found many other micro-machining applications, several of which are presented here.

  14. Toward the development of high-speed microscopic ESPI system for monitoring laser heating/drilling of alumina (Al(2)O(3)) substrates

    NASA Astrophysics Data System (ADS)

    Aslan, Mustafa

    2000-10-01

    The problem of cracking/failure of ceramic substrates during the laser shaping process (i.e. heat treatment, drilling, scribing, and cutting) due to large localized thermal stresses within the narrow heat-affected zone on the ceramics has been acknowledged by designers and electronic parts manufacturing industries. In addition to the large localized thermal stresses in the heat-affected zone, the brittle nature of ceramics catalyze the possibility of cracking/failure of the ceramic substrates during the laser shaping process. The knowledge of the stress distribution in the ceramic substrate is important in understanding the cracking/failure problem and solving it. Since it is impossible to measure stress directly, the physical parameters of the actual system subjected to the operating conditions, such as temperatures or displacements that can be related directly to stresses, can be measured experimentally. This research examined ceramic behavior under laser shaping. Specifically, it was conducted to develop an optimum optical measurement system in order to identify and measure the thermal deformation of alumina (Al2O 3) substrates during the laser heating/drilling process. Necessary research and development was performed to build a special electronic speckle pattern interferometry setup called high-speed microscopic ESPI (HSM-ESPI) system to measure transient out-of-plane deformation. By using commercial software the images of speckle patterns were image-processed to quantify whole-field transient out-of-plane displacement measurements. A CO2 laser beam radiation was used as the thermal loading and it was applied at the center of the substrates during the experiments. Local laser heating and drilling experiments were conducted depending on laser beam intensity. Another optical system, laser displacement meter (LDM), that measures single point absolute out-of-plane deformation, was setup to verify HSM-ESPI results. A finite element model (FEM) was developed in

  15. Multi-meter fiber-delivery and pulse self-compression of milli-Joule femtosecond laser and fiber-aided laser-micromachining.

    PubMed

    Debord, B; Alharbi, M; Vincetti, L; Husakou, A; Fourcade-Dutin, C; Hoenninger, C; Mottay, E; Gérôme, F; Benabid, F

    2014-05-05

    We report on damage-free fiber-guidance of milli-Joule energy-level and 600-femtosecond laser pulses into hypocycloid core-contour Kagome hollow-core photonic crystal fibers. Up to 10 meter-long fibers were used to successfully deliver Yb-laser pulses in robustly single-mode fashion. Different pulse propagation regimes were demonstrated by simply changing the fiber dispersion and gas. Self-compression to ~50 fs, and intensity-level nearing petawatt/cm(2) were achieved. Finally, free focusing-optics laser-micromachining was also demonstrated on different materials.

  16. High speed surface functionalization using direct laser interference patterning, towards 1 m2/min fabrication speed with sub-μm resolution

    NASA Astrophysics Data System (ADS)

    Lasagni, Andrés.; Roch, Teja; Bieda, Matthias; Benke, Dimitri; Beyer, Eckhard

    2014-03-01

    Periodic patterned surfaces can be used to provide unique surface properties in applications, such as biomaterials, surface engineering, photonics and sensor systems. Such periodic patterns can be produced using laser processing tools, showing significant advantages due to a precise modification of the surfaces without contamination, remote and contactless operation, flexibility, and precise energy deposition. On the other hand, the resolution of such laser based surface structuring methods, like direct laser writing, is generally inversely proportional to the fabrication speed. Therefore, the development of new laser structuring technologies as well as strategies offering both high speed and resolution is necessary. In this study, the fabrication of spatially ordered structures with micrometer and submicrometer lengthscales at high surface processing fabrication speed is demonstrated. The procedures shown here are applied to process both planar surfaces and also three dimensional components. Different application examples of structured surfaces on different materials are also described. The applications include the development of thin film structured electrodes to improve the efficiency of organic light emitting diodes (OLEDs) as well as the direct fabrication of decorative elements on technological steels. Finally, an example of fabrication at high fabrication speed is shown.

  17. Comparative histopathological analysis of human pulps after class I cavity preparation with a high-speed air-turbine handpiece or Er:YAG laser

    NASA Astrophysics Data System (ADS)

    Kina, J. F.; Benitez, P. C.; Lizarelli, R. F. Z.; Bagnato, V. S.; Martinez, T. C.; Oliveira, C. F.; Hebling, J.; Costa, C. A. S.

    2008-12-01

    The purpose of this study was to comparatively evaluate the response of human pulps after cavity preparation with different devices. Deep class I cavities were prepared in sound mandibular premolars using either a high-speed air-turbine handpiece (Group 1) or an Er:YAG laser (Group 2). Following total acid etching and the application of an adhesive system, all cavities were restored with composite resin. Fifteen days after the clinical procedure, the teeth were extracted and processed for analysis under optical microscopy. In Group 1 in which the average for the remaining dentin thickness (RDT) between the cavity floor and the coronal pulp was 909.5 μm, a discrete inflammatory response occurred in only one specimen with an RDT of 214 μm. However, tissue disorganization occurred in most specimens. In Group 2 (average RDT = 935.2 μm), the discrete inflammatory pulp response was observed in only one specimen (average RDT = 413 μm). It may be concluded that the high-speed air-turbine handpiece caused greater structural alterations in the pulp, although without inducing inflammatory processes.

  18. High Speed Research Program

    NASA Technical Reports Server (NTRS)

    Anderson, Robert E.; Corsiglia, Victor R.; Schmitz, Frederic H. (Technical Monitor)

    1994-01-01

    An overview of the NASA High Speed Research Program will be presented from a NASA Headquarters perspective. The presentation will include the objectives of the program and an outline of major programmatic issues.

  19. High-speed multi-exposure laser speckle contrast imaging with a single-photon counting camera.

    PubMed

    Dragojević, Tanja; Bronzi, Danilo; Varma, Hari M; Valdes, Claudia P; Castellvi, Clara; Villa, Federica; Tosi, Alberto; Justicia, Carles; Zappa, Franco; Durduran, Turgut

    2015-08-01

    Laser speckle contrast imaging (LSCI) has emerged as a valuable tool for cerebral blood flow (CBF) imaging. We present a multi-exposure laser speckle imaging (MESI) method which uses a high-frame rate acquisition with a negligible inter-frame dead time to mimic multiple exposures in a single-shot acquisition series. Our approach takes advantage of the noise-free readout and high-sensitivity of a complementary metal-oxide-semiconductor (CMOS) single-photon avalanche diode (SPAD) array to provide real-time speckle contrast measurement with high temporal resolution and accuracy. To demonstrate its feasibility, we provide comparisons between in vivo measurements with both the standard and the new approach performed on a mouse brain, in identical conditions.

  20. High-speed multi-THz-range mode-hop-free tunable mid-IR laser spectrometer.

    PubMed

    Courtois, Jérémie; Bouchendira, Rym; Cadoret, Malo; Ricciardi, Iolanda; Mosca, Simona; De Rosa, Maurizio; De Natale, Paolo; Zondy, Jean-Jacques

    2013-06-01

    We report on a widely (2.25 THz or 75 cm(-1)) and rapidly (4.5 THz/s) mode-hop-free (MHF) tunable mid-IR laser source at ~3.3 μm, consisting of a 5%-MgO:LiNbO(3) singly resonant optical parametric oscillator (SRO) pumped by an automated broadly MHF tunable extended-cavity diode laser (ECDL). The broad and rapid MHF tuning capability of the ECDL is readily transferred to the SRO idler wave owing to the quasi-noncritical pump spectral acceptance bandwidth of the quasi-phase-matching. Fast and broadband high-resolution Doppler spectroscopy measurements of the ν(3) band of CH(4) are presented to illustrate the performance of the mid-IR optical parametric oscillator spectrometer.

  1. Gain engineering for all-optical microwave and high speed pulse generation in mode-locked fiber lasers

    NASA Astrophysics Data System (ADS)

    Li, Fangxin; Helmy, Amr S.

    2014-03-01

    Pulsed sources based on approaches that employ only photonic components and no RF components will be discussed in this talk. Several technologies have been explored to generate actively mode-locked sources using electronically driven fiber ring cavities. However, for these sources the pulse repetition rate is usually limited by the bandwidth of the intracavity modulator. Filtering of highly-stable low repetition rate optical combs utilizing cavities such as Fabry-Perot etalons can be used to overcome this limitation. This scheme is not flexible as it requires highly precise control of ultrahigh finesse etalons which limits the repetition rate to the free spectral range of the filter. Pulsed sources based on semiconductor devices offer many advantages, including large gain bandwidth, rapid tunability, long-term stability. In this work we introduce a novel, simple method to generate optical clock with wavelength tunability using two continuous wave (CW) lasers. The lasers are injected into a conventional SOAs-based fiber ring laser. The beating signal generated by these two lasers causes the modulation of the SOA gain saturation inside the cavity. Thus, the SOA provides gain and functions as the modulator as well as the gain medium. When the lasing mode inside the cavity is amplified, it also results in gain-induced four wave mixing. The proposed technique is particularly versatile, overcoming the bandwidth limitation of other techniques, which require RF sources. Moreover, this technique provides the possibility for hybrid integration as it is comprised of semiconductor chips that can be heterogeneously integrated on a Si platform.

  2. Laser tabbed die: A repairable, high-speed die-interconnection technology. 1994 LDRD final report 93-SR-089

    SciTech Connect

    Malba, V.; Bernhardt, A.F.

    1995-09-01

    A unique technology for multichip module production is presented. The technology, called Laser Tabbed Die (L-TAB), consists of a method for forming surface-mount-type {open_quotes}gull wing{close_quotes} interconnects on bare dice. The dice are temporarily bonded to a sacrificial substrate which has a polymer thin film coated onto it. The gull wings are formed on the side of the die with a direct-write laser patterning process which allows vertical as well as horizontal image formation. Using the laser patterning system, trenches are formed in a positive electrodeposited photoresist (EDPR) which is plated onto a metal seed layer, allowing copper to be electroplated through the resultant mask. After stripping the resist and the metal seed layer, the polymer film on the substrate is dissolved, releasing the chip with the {open_quotes}gull wings{close_quotes} intact. The chips are then bonded onto a circuit board or permanent substrate with solder or conductive adhesive.

  3. Optical fiber Fabry-Perot interferometer cavity fabricated by femtosecond laser micromachining and fusion splicing for refractive index sensing.

    PubMed

    Liao, C R; Hu, T Y; Wang, D N

    2012-09-24

    We demonstrate a fiber in-line Fabry-Perot interferometer cavity sensor for refractive index measurement. The interferometer cavity is formed by drilling a micro-hole at the cleaved fiber end facet, followed by fusion splicing. A micro-channel is inscribed by femtosecond laser micromachining to vertically cross the cavity to allow liquid to flow in. The refractive index sensitivity obtained is ~994 nm/RIU (refractive index unit). Such a device is simple in configuration, easy for fabrication and reliable in operation due to extremely low temperature cross sensitivity of ~4.8 × 10(-6) RIU/°C.

  4. Two-dimensional time-resolved ultra-high speed imaging of K-alpha emission from short-pulse-laser interactions to observe electron recirculation

    DOE PAGES

    Nagel, S. R.; Chen, H.; Park, J.; ...

    2017-04-04

    Time resolved x-ray images with 7 ps resolution are recorded on relativistic short-pulse laser-plasma experiments using the dilation x-ray imager, a high-speed x-ray framing camera, sensitive to x-rays in the range of ≈1-17 keV. Furthermore, this capability enables a series of 2D x-ray images to be recorded at picosecond scales, which allows for the investigation of fast electron transport within the target with unprecedented temporal resolution. With an increase in the Kα-emission spot size over time we found that targets were thinner than the recirculation limit and is absent for thicker targets. Together with the observed polarization dependence of themore » spot size increase, this indicates that electron recirculation is relevant for the x-ray production in thin targets.« less

  5. InGaAlAs RW-based electro-absorption-modulated DFB-lasers for high-speed applications

    NASA Astrophysics Data System (ADS)

    Moehrle, Martin; Klein, Holger; Bornholdt, Carsten; Przyrembel, Georges; Sigmund, Ariane; Molzow, Wolf-Dietrich; Troppenz, Ute; Bach, Heinz-Gunter

    2014-05-01

    Electro-absorption modulated 10G and 25G DFB lasers (EML) are key components in transmission systems for long reach (up to 10 km) and extended reach (up to 80 km) applications. The next generation Ethernet will most likely be 400 Gb/s which will require components with even higher bandwidth. Commercially available EMLs are regarded as high-cost components due to their separate epitaxial butt-coupling growth process to separately optimize the DFB laser and the electro-absorption modulator (EAM). Alternatively the selective area growth (SAG) technique is used to achieve different MQW bandgaps in the DFB and EAM section of an EML. However for a lot of applications an emission wavelength within a narrow wavelength window is required enforcing a temperature controlled operation. All these applications can be covered with the developed EML devices that use a single InGaAlAs MQW waveguide for both the DFB and the EAM enabling a low-cost fabrication process similar to a conventional DFB laser diode. It will be shown that such devices can be used for 25Gb/s and 40Gb/s applications with excellent performance. By an additional monolithic integration of an impedance matching circuit the module fabrication costs can be reduced but also the modulation bandwidth of the devices can be further enhanced. Up to 70Gb/s modulation with excellent eye openings can be achieved. This novel approach opens the possibility for 100Gb/s NRZ EMLs and thus 4x100Gb/s NRZ EML-based transmitters in future. Also even higher bitrates seem feasible using more complex modulation formats such as e.g. DMT and PAM.

  6. A high speed and high gain CMOS receiver chip for a pulsed time-of-flight laser rangefinder

    NASA Astrophysics Data System (ADS)

    Yu, Jin-jin; Deng, Ruo-han; Yuan, Hong-hui; Chen, Yong-ping

    2011-06-01

    An integrated receiver channel for a pulsed time-of-flight (TOF) laser rangefinder has been designed. Pulsed TOF laser range finding devices using a laser diode transmitter can achieve millimeter-level distance measurement accuracy in a measurement range of several tens of meters to non-cooperative targets. The amplifier exploits the regulated cascade (RGC) configuration as the input-stage, thus achieving as large effective input trans-conductance as that of Si Bipolar or GaAs MESFET. The RGC input configuration isolates the input parasitic capacitance including photodiode capacitance from the bandwidth determination better than common-gate TIA. To enlarge the bandwidth, inductive peaking technology has been adopted. An active inductor (MOS-L) is used instead of spiral inductor in CMOS process. An R-2R resistor ladder is inserting between per-amplifier and post-amplifier as the variable attenuator for digital gain control purpose. The gain-bandwidth of a basic differential pair with resistive load is not large enough for broad band operation. A circuit solution to improve both gain and bandwidth of an amplifying stage is proposed. Traditional and modified Cherry-Hooper amplifiers are discussed and the cascading of several stages to constitute the post-amplifier is designed. The fully integrated one-chip solution is designed with Cadence IC design platform. The simulation result shows the bandwidth of the trans-impedance amplifier is 215MHz with the presence of a 2pF input capacitor and 5pF load capacitor. And the maximum trans-impedance gain is 136dB. The walk error is less than 1ns in 1:1000 dynamic range. The responsive time is less than 2.2ns.

  7. On the fabrication of minimizing bulges and reducing the feature dimensions of microchannels using novel CO2 laser micromachining

    NASA Astrophysics Data System (ADS)

    Chung, C. K.; Lin, S. L.

    2011-06-01

    The shape of a cross-microchannel in polymer is a common pattern in MEMS and can be fabricated using traditional CO2 laser micromachining in air-cooling environment. However, it always suffers some problems during the fabrication process such as bulges, splashes, resolidification and the appearance of a heat affected zone around the rims of channels. In this paper, a novel method of Foil-Assisted CO2 LAser Micromachining (FACLAM) is proposed to fabricate the cross-microchannels in polymethylmethacrylate (PMMA) by significantly diminishing the bulges and the channel's feature sizes. The feature size of the cross-channel can be greatly reduced from 229.1 to 63.6 µm with no clogging effect shown in the cross-junction position. The bulge height of the PMMA microchannel using FACLAM was reduced from the conventional size of 8.2 µm to as small as 0.2 µm. The ANSYS software was also used to analyze the temperature distribution of the PMMA microchannel during machining in air-cooling environment and with foil-mask assistance. The FACLAM approach can improve laser processing quality in air-cooling environment and has the merits of low-cost, easy fabrication and high surface quality.

  8. Optical coherence elastography based on high speed imaging of single-hot laser-induced acoustic waves at 16 kHz frame rate

    NASA Astrophysics Data System (ADS)

    Song, Shaozhen; Hsieh, Bao-Yu; Wei, Wei; Shen, Tueng; Pelivanov, Ivan; O'Donnell, Matthew; Wang, Ruikang K.

    2016-03-01

    Shear wave OCE (SW-OCE) is a novel technique that relies on the detection of the localized shear wave speed to map tissue elasticity. In this study, we demonstrate high speed imaging to capture single-shot transient shear wave propagation for SW-OCE. The fast imaging speed is achieved using a Fourier domain mode-locked (FDML) high-speed swept-source OCT (SS-OCT) system. The frame rate of shear wave imaging is 16 kHz, at an A-line rate of ~1.62 MHz, enabling the detection of high-frequency shear waves up to 8 kHz in bandwidth. Several measures are taken to improve the phase-stability of the SS-OCT system, and the measured displacement sensitivity is ~10 nanometers. To facilitate non-contact elastography, shear waves are generated with the photo-thermal effect using an ultra-violet pulsed laser. High frequency shear waves launched by the pulsed laser contain shorter wavelengths and carry rich localized elasticity information. Benefiting from single-shot acquisition, each SWI scan only takes 2.5 milliseconds, and the reconstruction of the elastogram can be performed in real-time with ~20 Hz refresh rate. SW-OCE measurements are demonstrated on porcine cornea ex vivo. This study is the first demonstration of an all-optical method to perform real-time 3D SW-OCE. It is hoped that this technique will be applicable in the clinic to obtain high-resolution localized quantitative measurements of tissue biomechanical properties.

  9. Laser micro-machining of waveguide devices for sub-mm and far IR interferometry and detector arrays

    NASA Astrophysics Data System (ADS)

    Drou't d'Aubigny, Christian Y.; Walker, Christopher K.; Golish, Dathon; Swain, Mark R.; Dumont, Philip J.; Lawson, Peter R.

    2003-02-01

    Laser induced, micro-chemical etching is a promising new technology that can be used to fabricate three dimensional structures many millimeters across with micrometer accuracy. Laser micromachining possesses a significant edge over more conventional techniques. It does not require the use of masks and is not confined to crystal planes. A non-contact process, it eliminates tool wear and vibration problems associated with classical milling machines. At the University of Arizona we have constructed the first such laser micromaching system optimized for the fabrication of THz and far IR waveguide and quasi-optical components. Our system can machine many millimeters across down to a few microns accuracy in a short time, with a remarkable surface finish. This paper presents the design, operation and performance of our system, and its applications to waveguide devices for sub millimeter and far IR interferometry.

  10. Single-shot selective laser micromachining of filtered arc deposited TiN films from chromium underlayer

    NASA Astrophysics Data System (ADS)

    Dowling, Andrew J.; Ghantasala, Muralidhar K.; Evans, Peter E.; Hayes, Jason P.; Harvey, Erol C.; Doyle, E. Derry

    2002-11-01

    This paper presents the results on single-shot laser micromachining of filtered arc deposited TiN films and compares the machining characteristics of the films deposited under partially and fully filtered conditions. Machining performance was evaluated in terms of patterning quality and the ability to perform selective removal of top TiN film with minimal interference to an underlying layer. TiN was arc-deposited onto silicon substrate with a chromium layer on the top. These films were analysed for their composition and microstructure using Rutherford Backscattering Spectroscopy (RBS) and Scanning Electron Microscopy (SEM) before and after laser machining. Under single shot conditions the effect of fluence on the machined features has been investigated. The results showed selective removal of TiN films with a single shot from the underlying Cr layer. Further, this work clearly shows a distinction between the laser machining characteristics of the films deposited under different filtering conditions and substrate temperatures.

  11. Application of a digital high-speed camera system for combustion research by using UV laser diagnostics under microgravity at Bremen drop tower

    NASA Astrophysics Data System (ADS)

    Renken, Hartmut; Bolik, T.; Eigenbrod, Ch.; Koenig, Jens; Rath, Hans J.

    1997-05-01

    This paper describes a digital high-speed camera- and recording system that will be used primary for combustion research under microgravity ((mu) g) at Bremen drop tower. To study the reactionzones during the process of combustion particularly OH-radicals are detected 2D by using the method of laser induced predissociation fluorescence (LIPF). A pulsed high-energy excimer lasersystem combined with a two- staged intensified CCD-camera allows a repetition rate of 250 images (256 X 256 pixel) per second, according to the maximum laser pulse repetition. The laser system is integrated at the top of the 110 m high evacutable drop tube. Motorized mirrors are necessary to achieve a stable beam position within the area of interest during the drop of the experiment-capsule. The duration of 1 drop will be 4.7 seconds (microgravity conditions). About 1500 images are captured and stored onboard the drop capsule 96 Mbyte RAM image storagesystem. After saving capsule and datas, a special PC-based image processing software visualizes the movies and extracts physical information out of the images. Now, after two and a half years of developments the system is working operational and capable of high temporal 2D LIPF- measuring of OH, H2O, O2, and CO concentrations and 2D temperature distribution of these species.

  12. Full-field linear and nonlinear measurements using Continuous-Scan Laser Doppler Vibrometry and high speed Three-Dimensional Digital Image Correlation

    NASA Astrophysics Data System (ADS)

    Ehrhardt, David A.; Allen, Matthew S.; Yang, Shifei; Beberniss, Timothy J.

    2017-03-01

    Spatially detailed dynamic measurements of thin, lightweight structures can be difficult to obtain due to the structure's low mass and complicated deformations under certain loading conditions. If traditional contacting sensors, such as accelerometers, strain gauges, displacement transducers, etc., are used, the total number of measurement locations available is limited by the weight added and the effect each sensor has on the local stiffness of the contact area. Other non-contacting sensors, such as Laser Doppler Vibrometers (LDV), laser triangulation sensors, proximity sensors, etc., do not affect the dynamics of a structure, but are limited to single point measurements. In contrast, a few recently developed non-contacting measurement techniques have been shown to be capable of simultaneously measuring the response over a wide measurement field. Two techniques are considered here: Continuous-Scan Laser Doppler Vibrometry (CSLDV) and high speed Three-Dimensional Digital Image Correlation (3D DIC). With the use of these techniques, unprecedented measurement resolution can be achieved. In this work, the linear and nonlinear deformations of a clamped, nominally flat beam and plate under steady state sinusoidal loading will be measured using both techniques. In order to assess their relative merits, the linear natural frequencies, mode shapes, and nonlinear deformation shapes measured with each method are compared. Both measurement systems give comparable results in many cases, although 3D DIC is more accurate for spatially complex deformations at large amplitudes and CSLDV is more accurate at low amplitudes and when the spatial deformation pattern is simpler.

  13. CW laser strategies for multi-parameter measurements of high-speed flows containing either NO or O2

    NASA Technical Reports Server (NTRS)

    Dirosa, M. D.; Chang, A. Y.; Davidson, D. F.; Hanson, R. K.

    1991-01-01

    Measurements of gasdynamic quantities were performed using a rapid-tuning CW dye laser to resolve Doppler-shifted spectral features in either the O2 Schumann-Runge bands or the NO gamma band near 225 nm. With the rapid-tuning capability, spectral features were acquired at a repetition rate of 4 kHz. Monitoring O2 transitions provided estimates of velocities while monitoring collision-broadened NO line pairs provided simultaneous measurements of velocity, temperature and pressure. Experiments were first performed in absorption within the transient one-dimensional flows generated in a shock tube. Agreement between measured and theoretical values, as calculated from one-dimensional shock relations, was typically better than 5 percent. The method was extended to fluorescence detection of NO in a static cell. Temperature and pressure were extracted from recorded profiles, and the results agreed well with expected values.

  14. High-speed flow measurements in a two-stroke engine by photon-correlation laser velocimetry.

    PubMed

    Fansler, T D; French, D T

    1993-07-20

    Three-dimensional mapping of the spatial structure and the temporal evolution of the air flow field in a commercially available two-stroke engine requires the ability to resolve a wide range of flow velocities (±250 m/s) at measurement locations near the cylinder wall and the piston crown. Laser-Doppler velocimetry that uses photon-correlation signal processing and Fourier-transform analysis permits ensemble-averaged velocity-distribution functions to be extracted from scattered-light signals that are sampled at nearly the Nyquist limit and whose strength is typically less than 1 photon per Doppler cycle. Selected results from a systematic study illustrate the impulsive jet-like flow through the transfer ports into the engine cylinder, the complexity of the resultant in-cylinder flow field, and the likelihood of large-scale flow-field variations from one engine cycle to another.

  15. High-speed phosphor thermometry.

    PubMed

    Fuhrmann, N; Baum, E; Brübach, J; Dreizler, A

    2011-10-01

    Phosphor thermometry is a semi-invasive surface temperature measurement technique utilising the luminescence properties of doped ceramic materials. Typically, these phosphor materials are coated onto the object of interest and are excited by a short UV laser pulse. Up to now, primarily Q-switched laser systems with repetition rates of 10 Hz were employed for excitation. Accordingly, this diagnostic tool was not applicable to resolve correlated temperature transients at time scales shorter than 100 ms. This contribution reports on the first realisation of a high-speed phosphor thermometry system employing a highly repetitive laser in the kHz regime and a fast decaying phosphor. A suitable material was characterised regarding its temperature lifetime characteristic and its measurement precision. Additionally, the influence of laser power on the phosphor coating was investigated in terms of heating effects. A demonstration of this high-speed technique has been conducted inside the thermally highly transient system of an optically accessible internal combustion engine. Temperatures have been measured with a repetition rate of 6 kHz corresponding to one sample per crank angle degree at 1000 rpm.

  16. High-speed phosphor thermometry

    NASA Astrophysics Data System (ADS)

    Fuhrmann, N.; Baum, E.; Brübach, J.; Dreizler, A.

    2011-10-01

    Phosphor thermometry is a semi-invasive surface temperature measurement technique utilising the luminescence properties of doped ceramic materials. Typically, these phosphor materials are coated onto the object of interest and are excited by a short UV laser pulse. Up to now, primarily Q-switched laser systems with repetition rates of 10 Hz were employed for excitation. Accordingly, this diagnostic tool was not applicable to resolve correlated temperature transients at time scales shorter than 100 ms. This contribution reports on the first realisation of a high-speed phosphor thermometry system employing a highly repetitive laser in the kHz regime and a fast decaying phosphor. A suitable material was characterised regarding its temperature lifetime characteristic and its measurement precision. Additionally, the influence of laser power on the phosphor coating was investigated in terms of heating effects. A demonstration of this high-speed technique has been conducted inside the thermally highly transient system of an optically accessible internal combustion engine. Temperatures have been measured with a repetition rate of 6 kHz corresponding to one sample per crank angle degree at 1000 rpm.

  17. High speed laser drilling of metals using a high repetition rate, high average power ultrafast fiber CPA system.

    PubMed

    Ancona, A; Röser, F; Rademaker, K; Limpert, J; Nolte, S; Tünnermann, A

    2008-06-09

    We present an experimental study on the drilling of metal targets with ultrashort laser pulses at high repetition rates (from 50 kHz up to 975 kHz) and high average powers (up to 68 Watts), using an ytterbium-doped fiber CPA system. The number of pulses to drill through steel and copper sheets with thicknesses up to 1 mm have been measured as a function of the repetition rate and the pulse energy. Two distinctive effects, influencing the drilling efficiency at high repetition rates, have been experimentally found and studied: particle shielding and heat accumulation. While the shielding of subsequent pulses due to the ejected particles leads to a reduced ablation efficiency, this effect is counteracted by heat accumulation. The experimental data are in good qualitative agreement with simulations of the heat accumulation effect and previous studies on the particle emission. However, for materials with a high thermal conductivity as copper, both effects are negligible for the investigated processing parameters. Therefore, the full power of the fiber CPA system can be exploited, which allows to trepan high-quality holes in 0.5mm-thick copper samples with breakthrough times as low as 75 ms.

  18. Underwater wireless transmission of high-speed QAM-OFDM signals using a compact red-light laser.

    PubMed

    Xu, Jing; Song, Yuhang; Yu, Xiangyu; Lin, Aobo; Kong, Meiwei; Han, Jun; Deng, Ning

    2016-04-18

    We first study the transmission property of red light in water in terms of extinction coefficient and channel bandwidth via Monte Carlo simulation, with an interesting finding that red light outperforms blue-green light in highly turbid water. We further propose and experimentally demonstrate a broadband underwater wireless optical communication system based on a simple and cost-effective TO56 red-light laser diode. We demonstrate a 1.324-Gb/s transmission at a bit error rate (BER) of 2.02 × 10-3 over a 6-m underwater channel, by using 128-QAM OFDM signals and a low-cost 150-MHz positive-intrinsic-negative photodetector, with a record spectral efficiency higher than 7.32 bits/Hz. By using an avalanche photodetector and 32-QAM OFDM signals, we have achieved a record bit rate of 4.883 Gb/s at a BER of 3.20 × 10-3 over a 6-m underwater channel.

  19. High-speed polarization sensitive optical coherence tomography scan engine based on Fourier domain mode locked laser.

    PubMed

    Bonesi, Marco; Sattmann, Harald; Torzicky, Teresa; Zotter, Stefan; Baumann, Bernhard; Pircher, Michael; Götzinger, Erich; Eigenwillig, Christoph; Wieser, Wolfgang; Huber, Robert; Hitzenberger, Christoph K

    2012-11-01

    We report on a new swept source polarization sensitive optical coherence tomography scan engine that is based on polarization maintaining (PM) fiber technology. The light source is a Fourier domain mode locked laser with a PM cavity that operates in the 1300 nm wavelength regime. It is equipped with a PM buffer stage that doubles the fundamental sweep frequency of 54.5 kHz. The fiberization allows coupling of the scan engine to different delivery probes. In a first demonstration, we use the system for imaging human skin at an A-scan rate of 109 kHz. The system illuminates the sample with circularly polarized light and measures reflectivity, retardation, optic axis orientation, and Stokes vectors simultaneously. Furthermore, depolarization can be quantified by calculating the degree of polarization uniformity (DOPU). The high scanning speed of the system enables dense sampling in both, the x- and y-direction, which provides the opportunity to use 3D evaluation windows for DOPU calculation. This improves the spatial resolution of DOPU images considerably.

  20. 450-nm GaN laser diode enables high-speed visible light communication with 9-Gbps QAM-OFDM.

    PubMed

    Chi, Yu-Chieh; Hsieh, Dan-Hua; Tsai, Cheng-Ting; Chen, Hsiang-Yu; Kuo, Hao-Chung; Lin, Gong-Ru

    2015-05-18

    A TO-38-can packaged Gallium nitride (GaN) blue laser diode (LD) based free-space visible light communication (VLC) with 64-quadrature amplitude modulation (QAM) and 32-subcarrier orthogonal frequency division multiplexing (OFDM) transmission at 9 Gbps is preliminarily demonstrated over a 5-m free-space link. The 3-dB analog modulation bandwidth of the TO-38-can packaged GaN blue LD biased at 65 mA and controlled at 25°C is only 900 MHz, which can be extended to 1.5 GHz for OFDM encoding after throughput intensity optimization. When delivering the 4-Gbps 16-QAM OFDM data within 1-GHz bandwidth, the error vector magnitude (EVM), signal-to-noise ratio (SNR) and bit-error-rate (BER) of the received data are observed as 8.4%, 22.4 dB and 3.5 × 10(-8), respectively. By increasing the encoded bandwidth to 1.5 GHz, the TO-38-can packaged GaN blue LD enlarges its transmission capacity to 6 Gbps but degrades its transmitted BER to 1.7 × 10(-3). The same transmission capacity of 6 Gbps can also be achieved with a BER of 1 × 10(-6) by encoding 64-QAM OFDM data within 1-GHz bandwidth. Using the 1.5-GHz full bandwidth of the TO-38-can packaged GaN blue LD provides the 64-QAM OFDM transmission up to 9 Gbps, which successfully delivers data with an EVM of 5.1%, an SNR of 22 dB and a BER of 3.6 × 10(-3) passed the forward error correction (FEC) criterion.

  1. Infra-red laser ablative micromachining of parylene-C on SiO2 substrates for rapid prototyping, high yield, human neuronal cell patterning.

    PubMed

    Raos, B J; Unsworth, C P; Costa, J L; Rohde, C A; Doyle, C S; Bunting, A S; Delivopoulos, E; Murray, A F; Dickinson, M E; Simpson, M C; Graham, E S

    2013-06-01

    Cell patterning commonly employs photolithographic methods for the micro fabrication of structures on silicon chips. These require expensive photo-mask development and complex photolithographic processing. Laser based patterning of cells has been studied in vitro and laser ablation of polymers is an active area of research promising high aspect ratios. This paper disseminates how 800 nm femtosecond infrared (IR) laser radiation can be successfully used to perform laser ablative micromachining of parylene-C on SiO2 substrates for the patterning of human hNT astrocytes (derived from the human teratocarcinoma cell line (hNT)) whilst 248 nm nanosecond ultra-violet laser radiation produces photo-oxidization of the parylene-C and destroys cell patterning. In this work, we report the laser ablation methods used and the ablation characteristics of parylene-C for IR pulse fluences. Results follow that support the validity of using IR laser ablative micromachining for patterning human hNT astrocytes cells. We disseminate the variation in yield of patterned hNT astrocytes on parylene-C with laser pulse spacing, pulse number, pulse fluence and parylene-C strip width. The findings demonstrate how laser ablative micromachining of parylene-C on SiO2 substrates can offer an accessible alternative for rapid prototyping, high yield cell patterning with broad application to multi-electrode arrays, cellular micro-arrays and microfluidics.

  2. CO(2)-laser micromachining and back-end processing for rapid production of PMMA-based microfluidic systems.

    PubMed

    Klank, Henning; Kutter, Jorg P; Geschke, Oliver

    2002-11-01

    In this article, we focus on the enormous potential of a CO(2)-laser system for rapidly producing polymer microfluidic structures. The dependence was assessed of the depth and width of laser-cut channels on the laser beam power and on the number of passes of the beam along the same channel. In the experiments the laser beam power was varied between 0 and 40 W and the passes were varied in the range of 1 to 7 times. Typical channel depths were between 100 and 300 microm, while the channels were typically 250 microm wide. The narrowest produced channel was 85 microm wide. Several bonding methods for microstructured PMMA [poly(methyl methacrylate)] parts were investigated, such as solvent-assisted glueing, melting, laminating and surface activation using a plasma asher. A solvent-assisted thermal bonding method proved to be the most time-efficient one. Using laser micromachining together with bonding, a three-layer polymer microstructure with included optical fibers was fabricated within two days. The use of CO(2)-laser systems to produce microfluidic systems has not been published before. These systems provide a cost effective alternative to UV-laser systems and they are especially useful in microfluidic prototyping due to the very short cycle time of production.

  3. High-speed ablation of ultradeep channels by a phase-conjugate dynamically controlled passively Q-switched Nd:YAG laser

    SciTech Connect

    Basiev, T T; Garnov, S V; Klimentov, S M; Pivovarov, P A; Gavrilov, A V; Smetanin, S N; Solokhin, S A; Fedin, A V

    2007-10-31

    Parameters of high-speed ablation of ultradeep channels by controlled pulse trains from a single-mode phase-conjugate dynamic cavity Nd:YAG laser emitting 20-200-ns, 70-250-mJ pulses at a pulse repetition rate in a train of 40-250 kHz are studied. The optimal parameters of ablation are found, for which a long-lived region of a hot rarefied gas was maintained in the ultradeep channel, which suppressed the shielding action of the surface plasma. The control of the lasing process during ablation optimises not only the heating and plasma formation, but also the removal of the processed material in the pause between laser pulses. Adaptive regulation of lasing parameters during ablation made it possible to obtain ultradeep channels of length 8-27 mm and diameters 80-300 {mu}m of the input and output holes in metals (aluminium, steel and Inconel 718 nickel superalloy) and ultrahard ceramics (Al{sub 2}O{sub 3}, AlN, SiC). (special issue devoted to the 25th anniversary of the a.m. prokhorov general physics institute)

  4. Laser micro-machining strategies for transparent brittle materials using ultrashort pulsed lasers

    NASA Astrophysics Data System (ADS)

    Bernard, Benjamin; Matylitsky, Victor

    2017-02-01

    Cutting and drilling of transparent materials using short pulsed laser systems are important industrial production processes. Applications ranging from sapphire cutting, hardened glass processing, and flat panel display cutting, to diamond processing are possible. The ablation process using a Gaussian laser beam incident on the topside of a sample with several parallel overlapping lines leads to a V-shaped structured groove. This limits the structuring depth for a given kerf width. The unique possibility for transparent materials to start the ablation process from the backside of the sample is a well-known strategy to improve the aspect ratio of the ablated features. This work compares the achievable groove depth depending on the kerf width for front-side and back-side ablation and presents the best relation between the kerf width and number of overscans. Additionally, the influence of the number of pulses in one burst train on the ablation efficiency is investigated. The experiments were carried out using Spirit HE laser from Spectra-Physics, with the features of adjustable pulse duration from <400 fs to 10 ps, three different repetition rates (100 kHz, 200 kHz and 400 kHz) and average output powers of >16 W ( at 1040 nm wavelength).

  5. High speed door assembly

    DOEpatents

    Shapiro, Carolyn

    1993-01-01

    A high speed door assembly, comprising an actuator cylinder and piston rods, a pressure supply cylinder and fittings, an electrically detonated explosive bolt, a honeycomb structured door, a honeycomb structured decelerator, and a structural steel frame encasing the assembly to close over a 3 foot diameter opening within 50 milliseconds of actuation, to contain hazardous materials and vapors within a test fixture.

  6. High speed door assembly

    DOEpatents

    Shapiro, C.

    1993-04-27

    A high speed door assembly is described, comprising an actuator cylinder and piston rods, a pressure supply cylinder and fittings, an electrically detonated explosive bolt, a honeycomb structured door, a honeycomb structured decelerator, and a structural steel frame encasing the assembly to close over a 3 foot diameter opening within 50 milliseconds of actuation, to contain hazardous materials and vapors within a test fixture.

  7. Laser micro-machinability of borosilicate glass surface-modified by electric field-assisted ion-exchange method

    NASA Astrophysics Data System (ADS)

    Matsusaka, S.; Kobayakawa, T.; Hidai, H.; Morita, N.

    2012-08-01

    In order to improve the laser micro-machinability of borosilicate glass, the glass surface was doped with metal (silver or copper) ions by an electric field-assisted ion-exchange method. Doped ions drifted and diffused into the glass substrate under a DC electric field. The concentration of metal ions within the doped area was approximately constant because the ion penetration was caused by substitution between dopant metal and inherent sodium ions. Nanosecond ultraviolet laser irradiation of metal-containing regions produced flat, smooth and defect-free holes. However, the shapes of holes were degraded when the processed hole bottoms reached ion penetration depths. A numerical analysis of ionic drift-diffusion behaviour in glass material under an electric field was also carried out. The calculated results for penetration depth and ionic flux showed good agreement with the measured values.

  8. High speed holographic digital recorder.

    PubMed

    Roberts, H N; Watkins, J W; Johnson, R H

    1974-04-01

    Concepts, feasibility experiments, and key component developments are described for a holographic digital record/reproduce system with the potential for 1.0 Gbit/sec rates and higher. Record rates of 500 Mbits/sec have been demonstrated with a ten-channel acoustooptic modulator array and a mode-locked, cavity-dumped argon-ion laser. Acoustooptic device technology has been advanced notably during the development of mode lockers, cavity dumpers, beam deflectors, and multichannel modulator arrays. The development of high speed multichannel photodetector arrays for the readout subsystem requires special attention. The feasibility of 1.0 Gbits/sec record rates has been demonstrated.

  9. High Speed Holographic Movie Camera

    NASA Astrophysics Data System (ADS)

    Hentschel, W.; Lauterborn, W.

    1985-08-01

    A high speed holographic movie camera system has been developed to investigate the dynamic behavior of cavitation bubbles in liquids. As a light source for holography, a high power multiply cavity-dumped argonion laser is used to record very long hologram series with framing rates up to 300 kHz. For separating successively recorded holograms, two spatial multiplexing techniques are applied simultaneously: rotation of the holographic plate or film and acousto-optic beam deflection. With the combination of these two techniques we achieve up to 4000 single holograms in one series.

  10. High Speed Holographic Movie Camera

    NASA Astrophysics Data System (ADS)

    Hentschel, W.; Lauterborn, W.

    1985-02-01

    A high speed holographic movie camera system has been developed in our laboratories at the Third Physical Institute of the University of Gdttingen. As a light source for holography a high power multiply cavity-dumped argonion laser is used to record very long hologram series with framing rates up to 300 kHz. For separating successively recorded holograms two spatial multiplexing techniques are applied simultaneously: rotating of the holographic plate or film and acousto-optic beam deflection. With the combination of these two techniques we achieve up to 4000 single holograms in one series.

  11. High Speed Video Insertion

    NASA Astrophysics Data System (ADS)

    Janess, Don C.

    1984-11-01

    This paper describes a means of inserting alphanumeric characters and graphics into a high speed video signal and locking that signal to an IRIG B time code. A model V-91 IRIG processor, developed by Instrumentation Technology Systems under contract to Instrumentation Marketing Corporation has been designed to operate in conjunction with the NAC model FHS-200 High Speed Video Camera which operates at 200 fields per second. The system provides for synchronizing the vertical and horizontal drive signals such that the vertical sync precisely coincides with five millisecond transitions in the IRIG time code. Additionally, the unit allows for the insertion of an IRIG time message as well as other data and symbols.

  12. Generation of multi-channel high-speed physical random numbers originated from two chaotic signals of mutually coupled semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Tang, X.; Wu, Z. M.; Wu, J. G.; Deng, T.; Fan, L.; Zhong, Z. Q.; Chen, J. J.; Xia, G. Q.

    2015-01-01

    We propose and experimentally demonstrate a novel technique to generate multi-channel high-speed physical random numbers (PRNs) by taking two chaotic signal outputs from mutually coupled semiconductor lasers (MC-SLs) as entropy sources. First, through controlling the operation parameters of the MC-SL system, two time-delay signature (TDS) suppressed chaotic signals can be obtained. Next, each of these two chaotic signals is sampled by an 8 bit analog-to-digital converter (ADC) with a sampling rate of 10 GHz, and then a bitwise exclusive-OR (XOR) operation on the corresponding bits in samples of the chaotic signal and its time delayed signal is implemented to obtain 8 bit XOR data. Furthermore, through selecting the five least significant bits (LSBs) of 8 bit XOR data to form 5 bit Boolean sequences, two sets of PRN streams with a rate up to 50 Gbits s-1 are generated and successfully pass the NIST statistical tests. Finally, merging these two sets of 50 Gbits s-1 PRN streams by an interleaving operation, another set of the 100 Gbits s-1 PRN stream, which meets all the quality criteria of NIST statistical tests, is also acquired.

  13. A novel optical apparatus for the study of rolling contact wear/fatigue based on a high-speed camera and multiple-source laser illumination.

    PubMed

    Bodini, I; Sansoni, G; Lancini, M; Pasinetti, S; Docchio, F

    2016-08-01

    Rolling contact wear/fatigue tests on wheel/rail specimens are important to produce wheels and rails of new materials for improved lifetime and performance, which are able to operate in harsh environments and at high rolling speeds. This paper presents a novel non-invasive, all-optical system, based on a high-speed video camera and multiple laser illumination sources, which is able to continuously monitor the dynamics of the specimens used to test wheel and rail materials, in a laboratory test bench. 3D macro-topography and angular position of the specimen are simultaneously performed, together with the acquisition of surface micro-topography, at speeds up to 500 rpm, making use of a fast camera and image processing algorithms. Synthetic indexes for surface micro-topography classification are defined, the 3D macro-topography is measured with a standard uncertainty down to 0.019 mm, and the angular position is measured on a purposely developed analog encoder with a standard uncertainty of 2.9°. The very small camera exposure time enables to obtain blur-free images with excellent definition. The system will be described with the aid of end-cycle specimens, as well as of in-test specimens.

  14. A novel optical apparatus for the study of rolling contact wear/fatigue based on a high-speed camera and multiple-source laser illumination

    NASA Astrophysics Data System (ADS)

    Bodini, I.; Sansoni, G.; Lancini, M.; Pasinetti, S.; Docchio, F.

    2016-08-01

    Rolling contact wear/fatigue tests on wheel/rail specimens are important to produce wheels and rails of new materials for improved lifetime and performance, which are able to operate in harsh environments and at high rolling speeds. This paper presents a novel non-invasive, all-optical system, based on a high-speed video camera and multiple laser illumination sources, which is able to continuously monitor the dynamics of the specimens used to test wheel and rail materials, in a laboratory test bench. 3D macro-topography and angular position of the specimen are simultaneously performed, together with the acquisition of surface micro-topography, at speeds up to 500 rpm, making use of a fast camera and image processing algorithms. Synthetic indexes for surface micro-topography classification are defined, the 3D macro-topography is measured with a standard uncertainty down to 0.019 mm, and the angular position is measured on a purposely developed analog encoder with a standard uncertainty of 2.9°. The very small camera exposure time enables to obtain blur-free images with excellent definition. The system will be described with the aid of end-cycle specimens, as well as of in-test specimens.

  15. Micromachined, Electrostatically Deformable Reflectors

    NASA Technical Reports Server (NTRS)

    Bartman, Randall K.; Wang, Paul K. C.; Miller, Linda M.; Kenny, Thomas W.; Kaiser, William J.; Hadaegh, Fred Y.; Agronin, Michael L.

    1995-01-01

    Micromachined, closed-loop, electrostatically actuated reflectors (microCLEARs) provide relatively simple and inexpensive alternatives to large, complex, expensive adaptive optics used to control wavefronts of beams of light in astronomy and in experimental laser weapons. Micromachining used to make deformable mirror, supporting structure, and actuation circuitry. Development of microCLEARs may not only overcome some of disadvantages and limitations of older adaptive optics but may also satisfy demands of potential market for small, inexpensive deformable mirrors in electronically controlled film cameras, video cameras, and other commercial optoelectronic instruments.

  16. High Speed Vortex Flows

    NASA Technical Reports Server (NTRS)

    Wood, Richard M.; Wilcox, Floyd J., Jr.; Bauer, Steven X. S.; Allen, Jerry M.

    2000-01-01

    A review of the research conducted at the National Aeronautics and Space Administration (NASA), Langley Research Center (LaRC) into high-speed vortex flows during the 1970s, 1980s, and 1990s is presented. The data reviewed is for flat plates, cavities, bodies, missiles, wings, and aircraft. These data are presented and discussed relative to the design of future vehicles. Also presented is a brief historical review of the extensive body of high-speed vortex flow research from the 1940s to the present in order to provide perspective of the NASA LaRC's high-speed research results. Data are presented which show the types of vortex structures which occur at supersonic speeds and the impact of these flow structures to vehicle performance and control is discussed. The data presented shows the presence of both small- and large scale vortex structures for a variety of vehicles, from missiles to transports. For cavities, the data show very complex multiple vortex structures exist at all combinations of cavity depth to length ratios and Mach number. The data for missiles show the existence of very strong interference effects between body and/or fin vortices and the downstream fins. It was shown that these vortex flow interference effects could be both positive and negative. Data are shown which highlights the effect that leading-edge sweep, leading-edge bluntness, wing thickness, location of maximum thickness, and camber has on the aerodynamics of and flow over delta wings. The observed flow fields for delta wings (i.e. separation bubble, classical vortex, vortex with shock, etc.) are discussed in the context of' aircraft design. And data have been shown that indicate that aerodynamic performance improvements are available by considering vortex flows as a primary design feature. Finally a discussing of a design approach for wings which utilize vortex flows for improved aerodynamic performance at supersonic speed is presented.

  17. High speed flywheel

    DOEpatents

    McGrath, Stephen V.

    1991-01-01

    A flywheel for operation at high speeds utilizes two or more ringlike coments arranged in a spaced concentric relationship for rotation about an axis and an expansion device interposed between the components for accommodating radial growth of the components resulting from flywheel operation. The expansion device engages both of the ringlike components, and the structure of the expansion device ensures that it maintains its engagement with the components. In addition to its expansion-accommodating capacity, the expansion device also maintains flywheel stiffness during flywheel operation.

  18. High speed flywheel

    SciTech Connect

    McGrath, S.V.

    1991-05-07

    This patent describes a flywheel for operation at high speed which utilizes two or more ringlike components arranged in a spaced concentric relationship for rotation about an axis and an expansion device interposed between the components for accommodating radial growth of the components resulting from flywheel operation. The expansion device engages both of the ringlike components, and the structure of the expansion device ensures that it maintains its engagement with the components. In addition to its expansion-accommodating capacity, the expansion device also maintains flywheel stiffness during flywheel operation.

  19. Development and application of a high-speed planar laser-induced fluorescence imaging system to evaluate liquid and vapor phases of sprays from a multi-hole diesel fuel injector

    NASA Astrophysics Data System (ADS)

    Parrish, S. E.; Zink, R. J.

    2013-02-01

    A high-speed imaging system capable of acquiring elastic scattering images and planar laser-induced fluorescence (PLIF) images in a near-simultaneous fashion has been developed. Acquiring both elastic scattering and PLIF images enables the liquid phase to be discriminated from the vapor phase. High-speed imaging allows the temporal evolution of flow structures to be evaluated. Images of sprays from a multi-hole diesel fuel injector operating under engine-like conditions were acquired. The vapor phase images reveal intricate fluid dynamic structures that exhibit a high degree of variability, indicative of a turbulent gas jet.

  20. High speed transient sampler

    DOEpatents

    McEwan, Thomas E.

    1995-01-01

    A high speed sampler comprises a meandered sample transmission line for transmitting an input signal, a straight strobe transmission line for transmitting a strobe signal, and a plurality of sampling gates along the transmission lines. The sampling gates comprise a four terminal diode bridge having a first strobe resistor connected from a first terminal of the bridge to the positive strobe line, a second strobe resistor coupled from the third terminal of the bridge to the negative strobe line, a tap connected to the second terminal of the bridge and to the sample transmission line, and a sample holding capacitor connected to the fourth terminal of the bridge. The resistance of the first and second strobe resistors is much higher than the signal transmission line impedance in the preferred system. This results in a sampling gate which applies a very small load on the sample transmission line and on the strobe generator. The sample holding capacitor is implemented using a smaller capacitor and a larger capacitor isolated from the smaller capacitor by resistance. The high speed sampler of the present invention is also characterized by other optimizations, including transmission line tap compensation, stepped impedance strobe line, a multi-layer physical layout, and unique strobe generator design. A plurality of banks of such samplers are controlled for concatenated or interleaved sample intervals to achieve long sample lengths or short sample spacing.

  1. High speed transient sampler

    DOEpatents

    McEwan, T.E.

    1995-11-28

    A high speed sampler comprises a meandered sample transmission line for transmitting an input signal, a straight strobe transmission line for transmitting a strobe signal, and a plurality of sampling gates along the transmission lines. The sampling gates comprise a four terminal diode bridge having a first strobe resistor connected from a first terminal of the bridge to the positive strobe line, a second strobe resistor coupled from the third terminal of the bridge to the negative strobe line, a tap connected to the second terminal of the bridge and to the sample transmission line, and a sample holding capacitor connected to the fourth terminal of the bridge. The resistance of the first and second strobe resistors is much higher than the signal transmission line impedance in the preferred system. This results in a sampling gate which applies a very small load on the sample transmission line and on the strobe generator. The sample holding capacitor is implemented using a smaller capacitor and a larger capacitor isolated from the smaller capacitor by resistance. The high speed sampler of the present invention is also characterized by other optimizations, including transmission line tap compensation, stepped impedance strobe line, a multi-layer physical layout, and unique strobe generator design. A plurality of banks of such samplers are controlled for concatenated or interleaved sample intervals to achieve long sample lengths or short sample spacing. 17 figs.

  2. High speed flywheel

    SciTech Connect

    McGrath, S.V.

    1990-01-01

    This invention relates generally to flywheels and relates more particularly to the construction of a high speed, low-mass flywheel. Flywheels with which this invention is to be compared include those constructed of circumferentially wound filaments or fibers held together by a matrix or bonding material. Flywheels of such construction are known to possess a relatively high hoop strength but a relatively low radial strength. Hoop-wound flywheels are, therefore, particularly susceptible to circumferential cracks, and the radial stress limitations of such a flywheel substantially limit its speed capabilities. It is an object of the present invention to provide a new and improved flywheel which experiences reduced radial stress at high operating speeds. Another object of the present invention is to provide flywheel whose construction allows for radial growth as flywheel speed increases while providing the necessary stiffness for transferring and maintaining kinetic energy within the flywheel. Still another object of the present invention is to provide a flywheel having concentrically-disposed component parts wherein rotation induced radial stresses at the interfaces of such component parts approach zero. Yet another object of the present invention is to provide a flywheel which is particularly well-suited for high speed applications. 5 figs.

  3. Laser surface texturing of cast iron steel: dramatic edge burr reduction and high speed process optimisation for industrial production using DPSS picosecond lasers

    NASA Astrophysics Data System (ADS)

    Bruneel, David; Kearsley, Andrew; Karnakis, Dimitris

    2015-07-01

    In this work we present picosecond DPSS laser surface texturing optimisation of automotive grade cast iron steel. This application attracts great interest, particularly in the automotive industry, to reduce friction between moving piston parts in car engines, in order to decrease fuel consumption. This is accomplished by partially covering with swallow microgrooves the inner surface of a piston liner and is currently a production process adopting much longer pulse (microsecond) DPSS lasers. Lubricated interface conditions of moving parts require from the laser process to produce a very strictly controlled surface topography around the laser formed grooves, whose edge burr height must be lower than 100 nm. To achieve such a strict tolerance, laser machining of cast iron steel was investigated using an infrared DPSS picosecond laser (10ps duration) with an output power of 16W and a repetition rate of 200 kHz. The ultrashort laser is believed to provide a much better thermal management of the etching process. All studies presented here were performed on flat samples in ambient air but the process is transferrable to cylindrical geometry engine liners. We will show that reducing significantly the edge burr below an acceptable limit for lubricated engine production is possible using such lasers and remarkably the process window lies at very high irradiated fluences much higher that the single pulse ablation threshold. This detailed experimental work highlights the close relationship between the optimised laser irradiation conditions as well as the process strategy with the final size of the undesirable edge burrs. The optimised process conditions are compatible with an industrial production process and show the potential for removing extra post)processing steps (honing, etc) of cylinder liners on the manufacturing line saving time and cost.

  4. Remote Transmission at High Speed

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Omni and NASA Test Operations at Stennis entered a Dual-Use Agreement to develop the FOTR-125, a 125 megabit-per-second fiber-optic transceiver that allows accurate digital recordings over a great distance. The transceiver s fiber-optic link can be as long as 25 kilometers. This makes it much longer than the standard coaxial link, which can be no longer than 50 meters.The FOTR-125 utilizes laser diode transmitter modules and integrated receivers for the optical interface. Two transmitters and two receivers are employed at each end of the link with automatic or manual switchover to maximize the reliability of the communications link. NASA uses the transceiver in Stennis High-Speed Data Acquisition System (HSDAS). The HSDAS consists of several identical systems installed on the Center s test stands to process all high-speed data related to its propulsion test programs. These transceivers allow the recorder and HSDAS controls to be located in the Test Control Center in a remote location while the digitizer is located on the test stand.

  5. HIGH SPEED CAMERA

    DOEpatents

    Rogers, B.T. Jr.; Davis, W.C.

    1957-12-17

    This patent relates to high speed cameras having resolution times of less than one-tenth microseconds suitable for filming distinct sequences of a very fast event such as an explosion. This camera consists of a rotating mirror with reflecting surfaces on both sides, a narrow mirror acting as a slit in a focal plane shutter, various other mirror and lens systems as well as an innage recording surface. The combination of the rotating mirrors and the slit mirror causes discrete, narrow, separate pictures to fall upon the film plane, thereby forming a moving image increment of the photographed event. Placing a reflecting surface on each side of the rotating mirror cancels the image velocity that one side of the rotating mirror would impart, so as a camera having this short a resolution time is thereby possible.

  6. High speed civil transport

    NASA Technical Reports Server (NTRS)

    Bogardus, Scott; Loper, Brent; Nauman, Chris; Page, Jeff; Parris, Rusty; Steinbach, Greg

    1990-01-01

    The design process of the High Speed Civil Transport (HSCT) combines existing technology with the expectation of future technology to create a Mach 3.0 transport. The HSCT was designed to have a range in excess of 6000 nautical miles and carry up to 300 passengers. This range will allow the HSCT to service the economically expanding Pacific Basin region. Effort was made in the design to enable the aircraft to use conventional airports with standard 12,000 foot runways. With a takeoff thrust of 250,000 pounds, the four supersonic through-flow engines will accelerate the HSCT to a cruise speed of Mach 3.0. The 679,000 pound (at takeoff) HSCT is designed to cruise at an altitude of 70,000 feet, flying above most atmospheric disturbances.

  7. High speed packet switching

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This document constitutes the final report prepared by Proteon, Inc. of Westborough, Massachusetts under contract NAS 5-30629 entitled High-Speed Packet Switching (SBIR 87-1, Phase 2) prepared for NASA-Greenbelt, Maryland. The primary goal of this research project is to use the results of the SBIR Phase 1 effort to develop a sound, expandable hardware and software router architecture capable of forwarding 25,000 packets per second through the router and passing 300 megabits per second on the router's internal busses. The work being delivered under this contract received its funding from three different sources: the SNIPE/RIG contract (Contract Number F30602-89-C-0014, CDRL Sequence Number A002), the SBIR contract, and Proteon. The SNIPE/RIG and SBIR contracts had many overlapping requirements, which allowed the research done under SNIPE/RIG to be applied to SBIR. Proteon funded all of the work to develop new router interfaces other than FDDI, in addition to funding the productization of the router itself. The router being delivered under SBIR will be a fully product-quality machine. The work done during this contract produced many significant findings and results, summarized here and explained in detail in later sections of this report. The SNIPE/RIG contract was completed. That contract had many overlapping requirements with the SBIR contract, and resulted in the successful demonstration and delivery of a high speed router. The development that took place during the SNIPE/RIG contract produced findings that included the choice of processor and an understanding of the issues surrounding inter processor communications in a multiprocessor environment. Many significant speed enhancements to the router software were made during that time. Under the SBIR contract (and with help from Proteon-funded work), it was found that a single processor router achieved a throughput significantly higher than originally anticipated. For this reason, a single processor router was

  8. High speed inscription of uniform, large-area laser-induced periodic surface structures in Cr films using a high repetition rate fs laser.

    PubMed

    Ruiz de la Cruz, A; Lahoz, R; Siegel, J; de la Fuente, G F; Solis, J

    2014-04-15

    We report on the fabrication of laser-induced periodic surface structures in Cr films upon high repetition rate fs laser irradiation (up to 1 MHz, 500 fs, 1030 nm), employing beam scanning. Highly regular large-area (9  cm2) gratings with a relative diffraction efficiency of 42% can be produced within less than 6 min. The ripple period at moderate and high fluences is 0.9 μm, with a small period of 0.5 μm appearing at lower energies. The role of the irradiation parameters on the characteristics of the laser-induced periodic surface structures (LIPSS) is studied and discussed in the frame of the models presently used. We have identified the polarization vector orientation with respect to the scan direction as a key parameter for the fabrication of high-quality, large-area LIPSS, which, for perpendicular orientation, allows the coherent extension of the sub-wavelength structure over macroscopic distances. The processing strategy is robust in terms of broad parameter windows and applicable to other materials featuring LIPSS.

  9. High speed civil transport

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This report discusses the design and marketability of a next generation supersonic transport. Apogee Aeronautics Corporation has designated its High Speed Civil Transport (HSCT): Supercruiser HS-8. Since the beginning of the Concorde era, the general consensus has been that the proper time for the introduction of a next generation Supersonic Transport (SST) would depend upon the technical advances made in the areas of propulsion (reduction in emissions) and material composites (stronger, lighter materials). It is believed by many in the aerospace industry that these beforementioned technical advances lie on the horizon. With this being the case, this is the proper time to begin the design phase for the next generation HSCT. The design objective for a HSCT was to develop an aircraft that would be capable of transporting at least 250 passengers with baggage at a distance of 5500 nmi. The supersonic Mach number is currently unspecified. In addition, the design had to be marketable, cost effective, and certifiable. To achieve this goal, technical advances in the current SST's must be made, especially in the areas of aerodynamics and propulsion. As a result of these required aerodynamic advances, several different supersonic design concepts were reviewed.

  10. High Speed Ice Friction

    NASA Astrophysics Data System (ADS)

    Seymour-Pierce, Alexandra; Sammonds, Peter; Lishman, Ben

    2014-05-01

    Many different tribological experiments have been run to determine the frictional behaviour of ice at high speeds, ostensibly with the intention of applying results to everyday fields such as winter tyres and sports. However, experiments have only been conducted up to linear speeds of several metres a second, with few additional subject specific studies reaching speeds comparable to these applications. Experiments were conducted in the cold rooms of the Rock and Ice Physics Laboratory, UCL, on a custom built rotational tribometer based on previous literature designs. Preliminary results from experiments run at 2m/s for ice temperatures of 271 and 263K indicate that colder ice has a higher coefficient of friction, in accordance with the literature. These results will be presented, along with data from further experiments conducted at temperatures between 259-273K (in order to cover a wide range of the temperature dependent behaviour of ice) and speeds of 2-15m/s to produce a temperature-velocity-friction map for ice. The effect of temperature, speed and slider geometry on the deformation of ice will also be investigated. These speeds are approaching those exhibited by sports such as the luge (where athletes slide downhill on an icy track), placing the tribological work in context.

  11. Nondestructive characterization of micromachined ceramics

    NASA Astrophysics Data System (ADS)

    Cooney, Adam; Hix, Kenneth E.; Yaney, Perry; Zhan, Qiwen; Dosser, Larry R.; Blackshire, James L.

    2005-05-01

    The aerospace, automotive, and electronic industries are finding increasing need for components made from silicon carbide (SiC) and silicon nitride (Si3N4). The development and use of miniaturized ceramic parts, in particular, is of significant interest in a variety of critical applications. As these application areas grow, manufacturers are being asked to find new and better solutions for machining and forming ceramic materials with microscopic precision. Recent advances in laser machining technologies are making precision micromachining of ceramics a reality. Questions regarding micromachining accuracy, residual melt region effects, and laser-induced microcracking are of critical concern during the machining process. In this activity, a variety of nondestructive inspection methods have been used to investigate the microscopic features of laser-machined ceramic components. The primary goal was to assess the micromachined areas for machining accuracy and microcracking using laser ultrasound, scanning electron microscopy, and white-light interference microscopic imaging of the machined regions.

  12. New random trigger-feature for ultrashort-pulsed laser increases throughput, accuracy and quality in micromachining applications

    NASA Astrophysics Data System (ADS)

    Oehler, Andreas; Ammann, Hubert; Benetti, Marco; Wassermann, Dominique; Jaeggi, Beat; Remund, Stefan; Neuenschwander, Beat

    2017-02-01

    For most micromachining applications, the laser focus has to be moved across the workpiece, either by steering the beam or by moving the workpiece. To maximize throughput, this movement should be as fast as possible. However, the required positioning accuracy often limits the obtainable speed. Especially the machining of small and complex features with high precision is constrained by the motion-system's maximum acceleration, limiting the obtainable moving spot velocity to very low values. In general, processing speed can vary widely within the same processing job. To obtain optimum quality at maximum throughput, ideally the pulse energy and the pulse-to-pulse pitch on the workpiece are kept constant. This is only possible if laser-pulses can be randomly triggered, synchronized to the current spot velocity. For ultrafast lasers this is not easily possible, as by design they are usually operated at a fixed pulse repetition rate. The pulse frequency can only be changed by dividing down with integer numbers which leads to a rather coarse frequency grid, especially when applied close to the maximum used operating frequency. This work reports on a new technique allowing random triggering of an ultrafast laser. The resulting timing uncertainty is less than ±25ns, which is negligible for real-world applications, energy stability is <2% rms. The technique allows using acceleration-ramps of the implemented motion system instead of applying additional override moves or skywriting techniques. This can reduce the processing time by up to 40%. Results of applying this technique to different processing geometries and strategies will be presented.

  13. Surface ablation and threshold determination of AlCu4SiMg aluminum alloy in picosecond pulsed laser micromachining

    NASA Astrophysics Data System (ADS)

    Zheng, Buxiang; Jiang, Gedong; Wang, Wenjun; Mei, Xuesong; Wang, Fangcheng

    2017-09-01

    Interaction of an ultrafast pulsed laser with material surface has become a research hotspot in recent years. Picosecond pulsed laser micromachining of AlCu4SiMg aluminum alloy and determination of the ablation threshold are the main research directions, which have vitally important theoretical significance and application value. The ablation characteristics of aluminum alloy under different focusing characteristics and energies were experimentally investigated with picosecond ultrafast laser pulses. The different ablation areas of laser Gaussian beam were divided based on ablation threshold, morphological characteristics, and interaction mechanism. The surface morphologies and feature sizes, including ablation width (i.e. diameter), ablation depth, ablation depth-to-width ratio, ablation area, ablation volume, and single pulse ablation rate, of the ablation craters were studied; and the variation of their ablation distributions with laser energy density were analyzed. The results showed that the irradiated surface morphologies of aluminum alloy under the focal lengths of 100 and 150 mm were better, and the ablation width increased with the increase of focal length; however, the ablation depth decreased clearly. More distinct morphological characteristics at high energy and better ablation quality at low energy were exhibited by ablation crater surface. Ablation area could be divided into ablation, melt, redeposition, phase-transformation, and modification regions, and the entire regions were dominated by multiphoton ionization and avalanche ionization. The ablation feature sizes, increasing monotonically in laser energy density, exhibited approximately linear dependence on the energy density at low energy-density. When the energy density reached a certain critical value, the increasing extent decelerated gradually, and tended increasingly towards saturation. According to the linear dependence of laser energy density on the ablation crater area, the average

  14. High speed transition prediction

    NASA Technical Reports Server (NTRS)

    Gasperas, Gediminis

    1992-01-01

    The main objective of this work period was to develop, acquire and apply state-of-the-art tools for the prediction of transition at high speeds at NASA Ames. Although various stability codes as well as basic state codes were acquired, the development of a new Parabolized Stability Equation (PSE) code was minimal. The time that was initially allocated for development was used on other tasks, in particular for the Leading Edge Suction problem, in acquiring proficiency in various graphics tools, and in applying these tools to evaluate various Navier-Stokes and Euler solutions. The second objective of this work period was to attend the Transition and Turbulence Workshop at NASA Langley in July and August, 1991. A report on the Workshop follows. From July 8, 1991 to August 2, 1991, the author participated in the Transition and Turbulence Workshop at NASA Langley. For purposes of interest here, analysis can be said to consist of solving simplified governing equations by various analytical methods, such as asymptotic methods, or by use of very meager computer resources. From the composition of the various groups at the Workshop, it can be seen that analytical methods are generally more popular in Great Britain than they are in the U.S., possibly due to historical factors and the lack of computer resources. Experimenters at the Workshop were mostly concerned with subsonic flows, and a number of demonstrations were provided, among which were a hot-wire experiment to probe the boundary layer on a rotating disc, a hot-wire rake to map a free shear layer behind a cylinder, and the use of heating strips on a flat plate to control instability waves and consequent transition. A highpoint of the demonstrations was the opportunity to observe the rather noisy 'quiet' supersonic pilot tunnel in operation.

  15. Optimization of micropipette fabrication by laser micromachining for application in an ultrafine atmospheric pressure plasma jet using response surface methodology

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Liu, Jingquan; Yang, Bin; Chen, Xiang; Wang, Xiaolin; Yang, Chunsheng

    2016-06-01

    The optimization of the laser micromachining process for special tapered micropipettes was investigated using response surface methodology. Three process parameters for the CO2 laser-based micropipette puller (P-2000, Sutter Instrument) were chosen as variables, namely heat, velocity and pull. The targeted length L TVS of the tapered variant section with a tip diameter of 10 μm was taken as a response. The optimum process parameters with L TVS of 7.3 mm were determined by analyzing the response surface three-dimension surface plots. The central composite design was selected to optimize the process variables, and the experimental data were fitted into a reduced cubic polynomial model. The high R 2 value (99.66%) and low coefficient of variation (0.73%) indicated the statistical significance of the model and good precision for the experiment. The optimization result showed that the best parameters were with the heat, velocity and pull values of 850, 53 and 170, respectively. The result was verified by a CO2 laser-based micropipette puller three times with length L TVS at 7.26 mm, 7.35 mm and 7.36 mm with the same optimized parameters. Then, the application to the ultrafine atmospheric pressure He/O2 plasma jets was carried out and micro-hole etching of the parylene-C film was realized with length L TVS at 6.29 mm, 7.35 mm and 8.02 mm. The results showed that the micro-plasma jet with an L TVS of 7.35 mm had the minimum applied voltage of 12.7 kV and the minimum micro-etching diameter of 45 μm with the deepest etching depth of 2.8 μm.

  16. The VK-8L High - Speed Camera

    NASA Astrophysics Data System (ADS)

    Venatovsky, I. V.; Tsukanov, A. A.; Kirillov, V. A.

    1985-02-01

    To enhance the time resolution of high-speed cine equipment during the investigation of rapidly flowing processes, a light source to illumi late an object under test is represented b7 solid-state laser exposure devices operating in the mode of Q-factor flodulation. With a high-speed eine cafiera being run in the continuous scanning mode, these devices will permit a sequence of fra Mlles to be obtained within a short exposure time of 150 ns to 200 nanoseconds. At scanning speeds of up to 250 m/s this will ensure satisfactory image quality from the slear viewpoint. In the case of faster continuous scanuin speeds and of shorter exposure times, it becomes necessary to run the high-speed cauera in the fl ode of frame-by-frame cinematography.

  17. Femtosecond laser micromachining for the realization of fully integrated photonic and microfluidic devices

    NASA Astrophysics Data System (ADS)

    Eaton, S. M.; Osellame, R.; Ramponi, R.

    2015-02-01

    Femtosecond laser microprocessing is a direct, maskless fabrication technique that has attracted much attention in the past 10 years due to its unprecedented versatility in the 3D patterning of transparent materials. Two common modalities of femtosecond laser microfabrication include buried optical waveguide writing and surface laser ablation, which have been applied to a wide range of transparent substrates including glasses, polymers and crystals. In two photon polymerization, a third modality of femtosecond laser fabrication, focused femtosecond laser pulses drive photopolymerization in photoresists, enabling the writing of complex 3D structures with submicrometer resolution. In this paper, we discuss several microdevices realized by these diverse modalities of femtosecond laser microfabrication, for applications in microfluidics, sensing and quantum information.

  18. Application of melt ejection criterion in simulation of micromachining with laser

    NASA Astrophysics Data System (ADS)

    Semak, Vladimir V.; Schriempf, J. T.; Knorovsky, G. A.; MacCallum, D. O.

    2003-07-01

    The theoretical criterion defining the threshold pulse energy and beam intensity required for melt ejection is proposed. The results of numerical simulation present dependencies of the threshold pulse energy and beam intensity as functions of laser pulse duration and beam radius. The experimental verification of proposed criterion is described and the comparison of theoretical predictions and measurements is presented. The criterion is applied for simulation of laser drilling metal foil with thickness in the range 25 μm - 125 μm using laser beam with 12 μm beam radius and pulse durations 10 ns and 100 ns. The computational results are used to interpret the results of experimental study of laser drilling of 125 μm aluminum foil using a single mode beam of a XeCl laser performed at the Nederlands Centrum voor Laser Research (NCLR) and the University of Twente. Additional results on Nd:YAG spot welds in pure Ni are also presented.

  19. High-energy picosecond hybrid fiber/crystal laser for thin films solar cells micromachining

    NASA Astrophysics Data System (ADS)

    Lecourt, Jean-Bernard; Boivinet, Simon; Bertrand, Anthony; Lekime, Didier; Hernandez, Yves

    2015-05-01

    We report on an hybrid fiber/crystal ultra-short pulsed laser delivering high pulse energy and high peak power in the picosecond regime. The laser is composed of a mode-lock fiber oscillator, a pulse picker and subsequent fiber amplifiers. The last stage of the laser is a single pass Nd:YVO4 solid-state amplifier. We believe that this combination of both technologies is a very promising approach for making efficient, compact and low cost lasers compatible with industrial requirements.

  20. Influence of the initial surface texture on the resulting surface roughness and waviness for micro-machining with ultra-short laser pulses (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Remund, Stefan M.; Jaeggi, Beat; Kramer, Thorsten; Neuenschwander, Beat

    2017-03-01

    The resulting surface roughness and waviness after processing with ultra-short pulsed laser radiation depend on the laser parameters as well as on the machining strategy and the scanning system. However the results depend on the material and its initial surface quality and finishing as well. The improvement of surface finishing represents effort and produces additional costs. For industrial applications it is important to reduce the preparation of a workpiece for laser micro-machining to optimize quality and reduce costs. The effects of the ablation process and the influence of the machining strategy and scanning system onto the surface roughness and waviness can be differenced due to their separate manner. By using the optimal laser parameters on an initially perfect surface, the ablation process mainly increases the roughness to a certain value for most metallic materials. However, imperfections in the scanning system causing a slight variation in the scanning speed lead to a raise of the waviness on the sample surface. For a basic understanding of the influence of grinding marks, the sample surfaces were initially furnished with regular grooves of different depths and spatial frequencies to gain a homogenous and well-defined original surface. On these surfaces the effect of different beam waists and machining strategy are investigated and the results are compared with a simulation of the process. Furthermore the behaviors of common surface finishes used in industrial applications for laser micro-machining are studied and the relation onto the resulting surface roughness and waviness is presented.

  1. Silicon Micromachining

    NASA Astrophysics Data System (ADS)

    Elwenspoek, Miko; Jansen, Henri V.

    2004-08-01

    This comprehensive book provides an overview of the key techniques used in the fabrication of micron-scale structures in silicon. Recent advances in these techniques have made it possible to create a new generation of microsystem devices, such as microsensors, accelerometers, micropumps, and miniature robots. The authors underpin the discussion of each technique with a brief review of the fundamental physical and chemical principles involved. They pay particular attention to methods such as isotropic and anisotropic wet chemical etching, wafer bonding, reactive ion etching, and surface micromachining. There is a special section on bulk micromachining, and the authors also discuss release mechanisms for movable microstructures. The book is a blend of detailed experimental and theoretical material, and will be of great interest to graduate students and researchers in electrical engineering and materials science whose work involves the study of micro-electromechanical systems (MEMS).

  2. Fiber laser micromachining of thin NiTi tubes for shape memory vascular stents

    NASA Astrophysics Data System (ADS)

    Liu, Lei; Li, Dong Bo; Tong, Yi Fei; Zhu, Yu Fu

    2016-07-01

    Nickel titanium (NiTi) alloy has widely been used in the vascular stent manufacturing due to its excellent properties. Neodymium-doped yttrium aluminum garnet (Nd:YAG) laser is commonly used for the preparation of metal vascular stents. Recently, fiber lasers have been used for stent profiling for better cutting quality. To investigate the cutting-kerf characters of NiTi vascular stents fabricated by fiber laser cutting, laser cutting experiments with thin NiTi tubes were conducted in this study, while NiTi sheets were used in other fiber laser cutting studies. Different with striation topography, new topographies such as layer topography and topography mixed with layers and striations were observed, and the underlying reason for new topographies was also discussed. Comparative research on different topographies was conducted through analyzing the surface roughness, kerf width, heat-affected zone (HAZ) and dross formation. Laser cutting process parameters have a comprehensive influence on the cutting quality; in this study, the process parameters' influences on the cutting quality were studied from the view of power density along the cutting direction. The present research provides a guideline for improving the cutting quality of NiTi vascular stents.

  3. Fabrication of low-loss ridge waveguides in z-cut lithium niobate by combination of ion implantation and UV picosecond laser micromachining

    NASA Astrophysics Data System (ADS)

    Stolze, M.; Herrmann, T.; L'huillier, J. A.

    2016-03-01

    Ridge waveguides in ferroelectric materials like LiNbO3 attended great interest for highly efficient integrated optical devices, for instance, electro-optic modulators, frequency converters and ring resonators. The main challenges are the realization of high index barrier towards the substrate and the processing of smooth ridges for minimized scattering losses. For fabricating ridges a variety of techniques, like chemical and wet etching as well as optical grade dicing, have been investigated in detail. Among them, laser micromachining offers a versatile and flexible processing technology, but up to now only a limited side wall roughness has been achieved by this technique. Here we report on laser micromachining of smooth ridges for low-loss optical waveguides in LiNbO3. The ridges with a top width of 7 µm were fabricated in z-cut LiNbO3 by a combination of UV picosecond micromachining and thermal annealing. The laser processing parameters show a strong influence on the achievable sidewall roughness of the ridges and were systematically investigated and optimized. Finally, the surface quality is further improved by an optimized thermal post-processing. The roughness of the ridges were analysed with confocal microscopy and the scattering losses were measured at an optical characterization wavelength of 632.8 nm by using the end-fire coupling method. In these investigations the index barrier was formed by multi-energy low dose oxygen ion implantation technology in a depth of 2.7 μm. With optimized laser processing parameters and thermal post-processing a scattering loss as low as 0.1 dB/cm has been demonstrated.

  4. High speed printing with polygon scan heads

    NASA Astrophysics Data System (ADS)

    Stutz, Glenn

    2016-03-01

    To reduce and in many cases eliminate the costs associated with high volume printing of consumer and industrial products, this paper investigates and validates the use of the new generation of high speed pulse on demand (POD) lasers in concert with high speed (HS) polygon scan heads (PSH). Associated costs include consumables such as printing ink and nozzles, provisioning labor, maintenance and repair expense as well as reduction of printing lines due to high through put. Targets that are applicable and investigated include direct printing on plastics, printing on paper/cardboard as well as printing on labels. Market segments would include consumer products (CPG), medical and pharmaceutical products, universal ID (UID), and industrial products. In regards to the POD lasers employed, the wavelengths include UV(355nm), Green (532nm) and IR (1064nm) operating within the repetition range of 180 to 250 KHz.

  5. Simultaneous high-speed gas property measurements at the exhaust gas recirculation cooler exit and at the turbocharger inlet of a multicylinder diesel engine using diode-laser-absorption spectroscopy.

    PubMed

    Jatana, Gurneesh S; Magee, Mark; Fain, David; Naik, Sameer V; Shaver, Gregory M; Lucht, Robert P

    2015-02-10

    A diode-laser-absorption-spectroscopy-based sensor system was used to perform high-speed (100 Hz to 5 kHz) measurements of gas properties (temperature, pressure, and H(2)O vapor concentration) at the turbocharger inlet and at the exhaust gas recirculation (EGR) cooler exit of a diesel engine. An earlier version of this system was previously used for high-speed measurements of gas temperature and H(2)O vapor concentration in the intake manifold of the diesel engine. A 1387.2 N m tunable distributed feedback diode laser was used to scan across multiple H(2)O absorption transitions, and the direct absorption signal was recorded using a high-speed data acquisition system. Compact optical connectors were designed to conduct simultaneous measurements in the intake manifold, the EGR cooler exit, and the turbocharger inlet of the engine. For measurements at the turbocharger inlet, these custom optical connectors survived gas temperatures as high as 800 K using a simple and passive arrangement in which the temperature-sensitive components were protected from high temperatures using ceramic insulators. This arrangement reduced system cost and complexity by eliminating the need for any active water or oil cooling. Diode-laser measurements performed during steady-state engine operation were within 5% of the thermocouple and pressure sensor measurements, and within 10% of the H(2)O concentration values derived from the CO(2) gas analyzer measurements. Measurements were also performed in the engine during transient events. In one such transient event, where a step change in fueling was introduced, the diode-laser sensor was able to capture the 30 ms change in the gas properties; the thermocouple, on the other hand, required 7.4 s to accurately reflect the change in gas conditions, while the gas analyzer required nearly 600 ms. To the best of our knowledge, this is the first implementation of such a simple and passive arrangement of high-temperature optical connectors as well

  6. Low-threshold whispering-gallery-mode microlasers fabricated in a Nd:glass substrate by three-dimensional femtosecond laser micromachining.

    PubMed

    Lin, Jintian; Xu, Yingxin; Song, Jiangxin; Zeng, Bin; He, Fei; Xu, Huailiang; Sugioka, Koji; Fang, Wei; Cheng, Ya

    2013-05-01

    We report on fabrication of whispering-gallery-mode microlasers in a Nd:glass chip by femtosecond laser three-dimensional micromachining. The main fabrication procedures include the fabrication of freestanding microdisks supported by thin pillars by femtosecond laser ablation of the glass substrate immersed in water, followed by CO2 laser annealing for surface smoothing. The quality (Q) factor of the fabricated microcavity is measured to be 1.065×10(6). Lasing is observed at a pump threshold as low as ~69 μW at room temperature with a continuous-wave laser diode operating at 780 nm. This technique allows for fabrication of microcavities of high Q factors in various dielectric materials, such as glasses and crystals.

  7. Comparison of Above Bandgap Laser and MeV Ion Induced Single Event Transients in High-Speed Si Photonic Devices

    NASA Technical Reports Server (NTRS)

    Laird, Jamie S.; Hirao, Toshio; Onoda, Shinobu; Itoh, Hisayoshi; Edmonds, Larry; Johnston, Allan

    2006-01-01

    We illustrate inherent differences between Single Event Transients generated by an above bandgap picosecond lasers and MeV heavy ions by comparing transient currents collected with an ion microbeam and picosecond laser with varying track waist.

  8. Comparison of Above Bandgap Laser and MeV Ion Induced Single Event Transients in High-Speed Si Photonic Devices

    NASA Technical Reports Server (NTRS)

    Laird, Jamie S.; Hirao, Toshio; Onoda, Shinobu; Itoh, Hisayoshi; Edmonds, Larry; Johnston, Allan

    2006-01-01

    We illustrate inherent differences between Single Event Transients generated by an above bandgap picosecond lasers and MeV heavy ions by comparing transient currents collected with an ion microbeam and picosecond laser with varying track waist.

  9. Environmental and Energy Quality Technologies. Task Order 0005: Organic Finishing Technologies, Sub Task 11: High Speed, Substrate Safe Specialty Coating Laser Stripping : Project: WP 2146

    DTIC Science & Technology

    2015-06-22

    hazardous materials and eliminating the hazardous waste streams associated with wheat starch , chemical strippers and hand sanding. Additionally, the laser...inspection and/or replacement. Standard coating removal methods include chemical strippers, media blasting (i.e., wheat starch , plastic...comparing the automated laser removal process to the combined process of full aircraft wheat starch and chemical stripping, the laser process projected

  10. Femtosecond laser 3D micromachining and its applications to biochip fabrication

    NASA Astrophysics Data System (ADS)

    Sugioka, Koji

    2014-03-01

    Femtosecond lasers have opened up new avenues in materials processing due to their unique characteristics of ultra-short pulse widths and extremely high peak intensities that induce strong absorption in even transparent materials due to nonlinear multiphoton absorption. Then, the femtosecond laser can directly fabricate three-dimensional microfluidic, micromechanic, microelectronic, and micro-optical components in glass. These microcomponents can be easily integrated in a single glass microchip, which enable us to fabricate functional biochips quickly screening large number of biological analytes. In this talk, the detailed fabrication procedure of biochips using the femtosecond laser and applications of the fabricated biochips to material synthesis, analysis of biochemical samples, and determination of functions of microorganisms are introduced.

  11. Microchips fabricated by femtosecond laser micromachining in glass for observation of aquatic microorganisms

    NASA Astrophysics Data System (ADS)

    Hanada, Y.; Sugioka, K.; Kawano, H.; Ishikawa, I.; Miyawaki, A.; Midorikawa, K.

    2008-02-01

    We demonstrate the fabrication of three-dimensional (3D) hollow microstructures embedded in photostructurable glass by a nonlinear multiphoton absorption process using a femtosecond (fs) laser. Fs laser direct writing followed by annealing and successive wet etching in dilute hydrofluoric (HF) acid solution resulted in the rapid manufacturing of microchips with 3-D hollow microstructures for the dynamic observation of living microorganisms in fresh water. The embedded microchannel structure enables us to analyze the continuous motion of Euglena gracilis and Dinoflagellate. Such microchips, referred to as nano-aquariums realize the efficient and highly functional observation of microorganisms.

  12. Fabrication of high-Q lithium niobate microresonators using femtosecond laser micromachining

    PubMed Central

    Lin, Jintian; Xu, Yingxin; Fang, Zhiwei; Wang, Min; Song, Jiangxin; Wang, Nengwen; Qiao, Lingling; Fang, Wei; Cheng, Ya

    2015-01-01

    We report on fabrication of high-Q lithium niobate (LN) whispering-gallery-mode (WGM) microresonators suspended on silica pedestals by femtosecond laser direct writing followed by focused ion beam (FIB) milling. The micrometer-scale (diameter ~82 μm) LN resonator possesses a Q factor of ~2.5 × 105 around 1550 nm wavelength. The combination of femtosecond laser direct writing with FIB enables high-efficiency, high-precision nanofabrication of high-Q crystalline microresonators. PMID:25627294

  13. Mechanism and experimental study on three-dimensional facula shaping in femtosecond laser micromachining

    NASA Astrophysics Data System (ADS)

    Pan, Xuetao; Tu, Dawei; Cai, Jianwen

    2015-10-01

    Because of the laser beam waist and diffraction effect of the lens, the focal spot light field in femtosecond laser microprocessing has an ellipsoidal spatial distribution. This leads to the gap between two processing layers increasing along the axial direction, and the distribution density of processing points decreasing along the horizontal direction. This directly reduces the resolution of the microprocessing, and badly affects the machining accuracy and surface quality. We established a mathematical model for three-dimensional (3-D) laser beam shaping based on the Fresnel diffraction theory and designed a kind of four-ring complex amplitude transmittance phase plate by using a global optimization algorithm and genetic algorithm to simultaneously realize transverse and axial 3-D shaping. We numerically showed that the transverse and axial gains of the focal facula after 3-D shaping are 0.77 and 0.68, respectively, where the corresponding peak energy ratio is 0.36, the transverse and axial sidelobe energies are 0.28 and 0.62, respectively, and the defocusing amount is -0.08. We also constructed a confocal/two-photon microscope system to experimentally achieve a better shaping effect in the case of femtosecond laser fabrication at a point on the thin film of a photochromic material.

  14. Impact of relative intensity noise of vertical-cavity surface-emitting lasers on optics-based micromachined audio and seismic sensors.

    PubMed

    Littrell, Robert; Hall, Neal A; Okandan, Murat; Olsson, Roy; Serkland, Darwin

    2007-10-01

    The relative intensity noise of vertical-cavity surface-emitting lasers (VCSELs) in the 100 mHz to 50 kHz frequency range is experimentally investigated using two representative single-mode VCSELs. Measurements in this frequency range are relevant to recently developed optical-based micromachined acoustic and accelerometer sensing structures that utilize VCSELs as the light source to form nearly monolithic 1 mm3 packages. Although this frequency regime is far lower than the gigahertz range relevant to optical communication applications for which VCSELs are primarily designed, the intensity noise is found to be low and well within the range of cancellation using basic reference detection principles.

  15. New methods to control quality and precision of micro-machining with femtosecond lasers

    NASA Astrophysics Data System (ADS)

    Le Harzic, Ronan; Sanner, Nicolas; Huot, Nicolas; Donnet, C.; Audouard, Eric; Laporte, Pierre

    2003-11-01

    Due to the rapid development of ultrashort lasers, quality of the machining is of prime interest for several applications. For instance deep marking of various materials. In this case, the depth can be controlled, knowing the ablation rate for the corresponding material. The evolution of ablation rates of Al, Cu and Ni are given in relation to the energy density. In metals the effect of thermal diffusion has to be taken into account to control collateral effects and especially the heat affected zone.

  16. Optical Micromachining

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Under an SBIR (Small Business Innovative Research) with Marshall Space Flight Center, Potomac Photonics, Inc., constructed and demonstrated a unique tool that fills a need in the area of diffractive and refractive micro-optics. It is an integrated computer-aided design and computer-aided micro-machining workstation that will extend the benefits of diffractive and micro-optic technology to optical designers. Applications of diffractive optics include sensors and monitoring equipment, analytical instruments, and fiber optic distribution and communication. The company has been making diffractive elements with the system as a commercial service for the last year.

  17. Temporally focused femtosecond laser pulses for low numerical aperture micromachining through optically transparent materials.

    PubMed

    Vitek, Dawn N; Adams, Daniel E; Johnson, Adrea; Tsai, Philbert S; Backus, Sterling; Durfee, Charles G; Kleinfeld, David; Squier, Jeffrey A

    2010-08-16

    Temporal focusing of spatially chirped femtosecond laser pulses overcomes previous limitations for ablating high aspect ratio features with low numerical aperture (NA) beams. Simultaneous spatial and temporal focusing reduces nonlinear interactions, such as self-focusing, prior to the focal plane so that deep (approximately 1 mm) features with parallel sidewalls are ablated at high material removal rates (25 microm(3) per 80 microJ pulse) at 0.04-0.05 NA. This technique is applied to the fabrication of microfluidic devices by ablation through the back surface of thick (6 mm) fused silica substrates. It is also used to ablate bone under aqueous immersion to produce craniotomies.

  18. Micromachining of optically transparent materials by laser ablation of a solution containing pyrene

    NASA Astrophysics Data System (ADS)

    Yabe, Akira; Niino, Hiroyuki; Wang, Jun

    2001-01-01

    Optically transparent materials such as fused silica, quartz crystal, calcium fluoride, and fluorocarbon polymer were etched upon irradiation of organic solution containing pyrene with a conventional KrF or XeCl excimer laser. Threshold fluences for etching were 240 mJ/cm2 for fused silica, 330 mJ/cm2 for quartz crystal, 740 mJ/cm2 for calcium fluoride, and 45 mJ/cm2 for fluorocarbon polymer. These threshold values were remarkably low compared with those of direct ablation by using conventional lasers. Their etch rates remarkably depended on a concentration of pyrene: the etch rate became higher as the pyrene concentration increased. It means that pyrene molecules play an important role in this process. The mechanisms for this process is discussed by cyclic multiphotonic absorption of pyrene in the excited states, thermal relaxation, and formation of super-heated solution. As the results suggest, the process is based on the combination of two physical processes in the interface between the transparent materials and the liquid: one is a heating process by a super-heated liquid and the other is an attacking process by a high temperature and pressure vapor. The mechanism is also referred to thermal properties of materials.

  19. Laser-micromachined, chip-scaled ceramic carriers for implantable neurostimulators.

    PubMed

    Guenther, Thomas; Mintri, Apoorv; Lim, William W; Jung, Louis H; Lehmann, Torsten; Lovell, Nigel H; Suaning, Gregg J

    2011-01-01

    Hermetic encapsulation of long-term implantable devices using ceramics has been investigated over several decades. Our studies focus on the miniaturization of ceramic encapsulations for large numbers of stimulation channels. Laser-patterning of screen printed platinum (Pt) paste on cofired ceramics has been shown to enable the construction of features comparable in size to classical screen printing. A novel technique for embedding Pt structures into the surface of Al(2)O(3) substrates is shown to produce features with a line width minimum of 20 μm and a pitch of 40 μm. Polishing the ceramic substrates enables flip-chip bonding of application specific integrated circuits (ASIC) using gold stud bumps. A new technique for fine tuning of an ASIC stimulator with stud bump bridges is described. The technique eliminates the need for wire bond loops and increases reliability and integration density of the system, which are major requirements used to construct a visual prosthesis or other implantable devices requiring miniaturization. The methods for laser-patterned Pt tracks in alumina for fine pitch structures are described. Feasibility studies for flip-chip bonding and stud bump bridges were undertaken and the results were found to be promising.

  20. High-speed massively parallel scanning

    DOEpatents

    Decker, Derek E.

    2010-07-06

    A new technique for recording a series of images of a high-speed event (such as, but not limited to: ballistics, explosives, laser induced changes in materials, etc.) is presented. Such technique(s) makes use of a lenslet array to take image picture elements (pixels) and concentrate light from each pixel into a spot that is much smaller than the pixel. This array of spots illuminates a detector region (e.g., film, as one embodiment) which is scanned transverse to the light, creating tracks of exposed regions. Each track is a time history of the light intensity for a single pixel. By appropriately configuring the array of concentrated spots with respect to the scanning direction of the detection material, different tracks fit between pixels and sufficient lengths are possible which can be of interest in several high-speed imaging applications.

  1. Narrow linewidth comb realized with a mode-locked fiber laser using an intra-cavity waveguide electro-optic modulator for high-speed control.

    PubMed

    Iwakuni, Kana; Inaba, Hajime; Nakajima, Yoshiaki; Kobayashi, Takumi; Hosaka, Kazumoto; Onae, Atsushi; Hong, Feng-Lei

    2012-06-18

    We have developed an optical frequency comb using a mode-locked fiber ring laser with an intra-cavity waveguide electro-optic modulator controlling the optical length in the laser cavity. The mode-locking is achieved with a simple ring configuration and a nonlinear polarization rotation mechanism. The beat note between the laser and a reference laser and the carrier envelope offset frequency of the comb were simultaneously phase locked with servo bandwidths of 1.3 MHz and 900 kHz, respectively. We observed an out-of-loop beat between two identical combs, and obtained a coherent δ-function peak with a signal to noise ratio of 70 dB/Hz.

  2. High-Speed Electrochemical Imaging.

    PubMed

    Momotenko, Dmitry; Byers, Joshua C; McKelvey, Kim; Kang, Minkyung; Unwin, Patrick R

    2015-09-22

    The design, development, and application of high-speed scanning electrochemical probe microscopy is reported. The approach allows the acquisition of a series of high-resolution images (typically 1000 pixels μm(-2)) at rates approaching 4 seconds per frame, while collecting up to 8000 image pixels per second, about 1000 times faster than typical imaging speeds used up to now. The focus is on scanning electrochemical cell microscopy (SECCM), but the principles and practicalities are applicable to many electrochemical imaging methods. The versatility of the high-speed scan concept is demonstrated at a variety of substrates, including imaging the electroactivity of a patterned self-assembled monolayer on gold, visualization of chemical reactions occurring at single wall carbon nanotubes, and probing nanoscale electrocatalysts for water splitting. These studies provide movies of spatial variations of electrochemical fluxes as a function of potential and a platform for the further development of high speed scanning with other electrochemical imaging techniques.

  3. SEAL FOR HIGH SPEED CENTRIFUGE

    DOEpatents

    Skarstrom, C.W.

    1957-12-17

    A seal is described for a high speed centrifuge wherein the centrifugal force of rotation acts on the gasket to form a tight seal. The cylindrical rotating bowl of the centrifuge contains a closure member resting on a shoulder in the bowl wall having a lower surface containing bands of gasket material, parallel and adjacent to the cylinder wall. As the centrifuge speed increases, centrifugal force acts on the bands of gasket material forcing them in to a sealing contact against the cylinder wall. This arrangememt forms a simple and effective seal for high speed centrifuges, replacing more costly methods such as welding a closure in place.

  4. Laser-Micromachined and Laminated Microfluidic Components for Miniaturized Thermal, Chemical and Biological Systems

    SciTech Connect

    Martin, Peter M. ); Matson, Dean W. ); Bennett, Wendy D. ); Stewart, Donald C. ); Lin, Yuehe )

    1999-01-01

    Microchannel microfluidic components are being developed for heat transfer, chemical reactor, chemical analysis, and biological analytical applications. Specific applications include chemical sensing, DNA replication, blodd analysis, capillary electrophoresis, fuel cell reactors, high temperature chemical reactors, heat pumps, combustors, and fuel processors. Two general types of component architectures have been developed and the fabrication processes defined. All involve a lamination scheme using plastic, ceramic, or metal laminates, as opposed to planar components. The first type is a stacked architecture that utilizes functionality built in each layer, with fluid flow interconnects between layers. Each layer of the laminate has specific microchannel geometry, and performs a specific function (such as mixing, heat exchange, or chemical reaction). Polymeric materials are used primarily. Fabrication processes used are laser micromaching, wet and dry etching, and coating deposition. T he laminates can also be micromolded plastics. The second architecture employs laminates to form internal microchannels and interconnects. Materials include ceramic tapes and high temperature metals. Catalysts can be placed in the microchannels. Fabrication processes used are diffusion bonding, ceramic bonding and firing, photochemical etching, and electrochemical micromaching. Bonding, thus sealing, the laminates is an important issue. Process conditions have been developed to reduce distortion of the laminates and to hermetically seal the components.

  5. Development and Characterization of a High Speed Mid-IR Tunable Diode Laser Absorption Spectrometer for CO and CO2 Detection in Detonation Events

    DTIC Science & Technology

    2014-03-27

    complexity. Figure adapted from Engel [9]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.5 A HITEMP Simulated stick spectrum...third” atom added to the molecule greatly increases the spectral complexity. Figure adapted from Engel [9]. choose a transition that is active in the...2011. [8] Demtroder, Wolfgang. Laser Spectroscopy Volume 2: Experimental Techniques, volume 2. Springer, fourth edition, 2008. [9] Engel , Thomas

  6. High speed multiwire photon camera

    NASA Technical Reports Server (NTRS)

    Lacy, Jeffrey L. (Inventor)

    1991-01-01

    An improved multiwire proportional counter camera having particular utility in the field of clinical nuclear medicine imaging. The detector utilizes direct coupled, low impedance, high speed delay lines, the segments of which are capacitor-inductor networks. A pile-up rejection test is provided to reject confused events otherwise caused by multiple ionization events occuring during the readout window.

  7. High speed multiwire photon camera

    NASA Technical Reports Server (NTRS)

    Lacy, Jeffrey L. (Inventor)

    1989-01-01

    An improved multiwire proportional counter camera having particular utility in the field of clinical nuclear medicine imaging. The detector utilizes direct coupled, low impedance, high speed delay lines, the segments of which are capacitor-inductor networks. A pile-up rejection test is provided to reject confused events otherwise caused by multiple ionization events occurring during the readout window.

  8. High-speed multispectral confocal biomedical imaging

    PubMed Central

    Carver, Gary E.; Locknar, Sarah A.; Morrison, William A.; Krishnan Ramanujan, V.; Farkas, Daniel L.

    2014-01-01

    Abstract. A new approach for generating high-speed multispectral confocal images has been developed. The central concept is that spectra can be acquired for each pixel in a confocal spatial scan by using a fast spectrometer based on optical fiber delay lines. This approach merges fast spectroscopy with standard spatial scanning to create datacubes in real time. The spectrometer is based on a serial array of reflecting spectral elements, delay lines between these elements, and a single element detector. The spatial, spectral, and temporal resolution of the instrument is described and illustrated by multispectral images of laser-induced autofluorescence in biological tissues. PMID:24658777

  9. High-speed scanning ablation of dental hard tissues with a λ=9.3-μm CO2 laser: heat accumulation and peripheral thermal damage

    NASA Astrophysics Data System (ADS)

    Nguyen, Daniel; Staninec, Michal; Lee, Chulsung; Fried, Daniel

    2010-02-01

    A mechanically scanned CO2 laser operated at high laser pulse repetition rates can be used to rapidly and precisely remove dental decay. This study aims to determine whether these laser systems can safely ablate enamel and dentin without excessive heat accumulation and peripheral thermal damage. Peripheral thermal damage can adversely impact the mechanical strength of the irradiated tissue, particularly for dentin, and reduce the adhesion characteristics of the modified surfaces. Samples were derived from noncarious extracted molars. Pulpal temperatures were recorded using microthermocouples situated at the pulp chamber roof of samples (n=12), which were occlusally ablated using a rapid-scanning, water-cooled 300 Hz CO2 laser over a two minute time course. The mechanical strength of facially ablated dentin (n=10) was determined via four-point bend test and compared to control samples (n=10) prepared with 320 grit wet sand paper to simulate conventional preparations. Composite-to-enamel bond strength was measured via single-plane shear test for ablated/non-etched (n=10) and ablated/acid-etched (n=8) samples and compared to control samples (n=9) prepared by 320 grit wet sanding. Thermocouple measurements indicated that the temperature remained below ambient temperature at 19.0°C (s.d.=0.9) if water-cooling was used. There was no discoloration of either dentin and enamel, the treated surfaces were uniformly ablated and there were no cracks observable on the laser treated surfaces. Fourpoint bend tests yielded mean mechanical strengths of 18.2 N (s.d.=4.6) for ablated dentin and 18.1 N (s.d.=2.7) for control (p>0.05). Shear tests yielded mean bond strengths of 31.2 MPa (s.d.=2.5, p<0.01) for ablated/acid-etched samples, 5.2 MPa (s.d.=2.4, p<0.001) for ablated/non-etched samples, and 37.0 MPa (s.d.=3.6) for control. The results indicate that a rapid-scanning 300 Hz CO2 laser can effectively ablate dentin and enamel without excessive heat accumulation and with minimal

  10. Laser velocimeter systems analysis applied to a flow survey above a stalled wing. [conducted in Langley high-speed 7 by 10 foot tunnel

    NASA Technical Reports Server (NTRS)

    Young, W. H., Jr.; Meyers, J. F.; Hepner, T. E.

    1977-01-01

    A laser velocimeter operating in the backscatter mode was used to survey the flow above a stalled wing. Polarization was used to separate the two orthogonal velocity components of the fringe-type laser velocimeter, and digital counters were used for data processing. The velocities of the kerosene seed particles were measured with less than 2 percent uncertainty. The particle velocity measurements were collected into histograms. The flow field survey was carried out above an aspect-ratio-8 stalled wing with an NACA 0012 section. The angle of attack was 19.5 deg, the Mach number was 0.49, and the Reynolds number was 1,400,000. The flow field was characterized by the periodic shedding of discrete vortices from near the crest of the airfoil.

  11. Dissolution studies of bovine dental enamel surfaces modified by high-speed scanning ablation with a lambda = 9.3-microm TEA CO(2) laser.

    PubMed

    Fried, Daniel; Featherstone, John D B; Le, Charles Q; Fan, Kenneth

    2006-10-01

    Previous studies have demonstrated that lasers can be used to modify the chemical composition of dental enamel to render the mineral phase more resistant to acid dissolution with minimal peripheral thermal damage. Transverse excited atmospheric (TEA) CO(2) lasers tuned to the strong mineral absorption of hydroxyapatite (HAP) near lambda = 9 microm are well-suited for the efficient ablation of dental hard tissues if the laser-pulse is stretched to greater than 5-10 microseconds to avoid plasma shielding phenomena. Moreover, TEA CO(2) lasers can be operated at very high repetition rates and are inherently less expensive and more versatile than Er:YAG and Er:YSGG solid-state lasers. In this study a lambda = 9.3-microm TEA CO(2) with a pulse duration of 8 microseconds and a repetition rate of 300 Hz was used to uniformly treat bovine enamel surfaces at ablative irradiation intensities. We hypothesized that a uniform surface layer of modified enamel of improved crystallinity and CaP phase composition would be formed with an enhanced resistance to acid-dissolution in the ablated areas at higher scanning rates used with the water spray. Such a modified layer of enamel formed at the base and walls of a cavity preparation under the irradiation conditions employed in this study have the potential to inhibit secondary caries under sealants and restorations. The surfaces of bovine enamel blocks (3 x 3 mm(2)) were rapidly scanned across the laser beam at rates of 2, 3, and 6 mm/second with and without a water-spray at an incident fluence of 30 J/cm(2). The resistance to acid dissolution was evaluated using controlled surface dissolution experiments on laser-irradiated and control samples. The groups irradiated at a fluence of 30 J/cm(2) with a repetition rate of 300 Hz and a high scan rate of 6 mm/second with and without water-cooling significantly reduced the overall surface dissolution rates (P < 0.001). At low scan rates (2-3 mm/second) excessive heat deposition resulted in

  12. High-speed assembly language (80386/80387) programming for laser spectra scan control and data acquisition providing improved resolution water vapor spectroscopy

    NASA Technical Reports Server (NTRS)

    Allen, Robert J.

    1988-01-01

    An assembly language program using the Intel 80386 CPU and 80387 math co-processor chips was written to increase the speed of data gathering and processing, and provide control of a scanning CW ring dye laser system. This laser system is used in high resolution (better than 0.001 cm-1) water vapor spectroscopy experiments. Laser beam power is sensed at the input and output of white cells and the output of a Fabry-Perot. The assembly language subroutine is called from Basic, acquires the data and performs various calculations at rates greater than 150 faster than could be performed by the higher level language. The width of output control pulses generated in assembly language are 3 to 4 microsecs as compared to 2 to 3.7 millisecs for those generated in Basic (about 500 to 1000 times faster). Included are a block diagram and brief description of the spectroscopy experiment, a flow diagram of the Basic and assembly language programs, listing of the programs, scope photographs of the computer generated 5-volt pulses used for control and timing analysis, and representative water spectrum curves obtained using these programs.

  13. Correlative microscopy including CLSM and SEM to improve high-speed, high-resolution laser-engraved print and embossing forms

    NASA Astrophysics Data System (ADS)

    Bohrer, Markus; Schweitzer, Michael; Nirnberger, Robert; Weinberger, Bernhard

    2015-10-01

    The industrial market for processing large-scale films has seen dramatic changes since the 1980s and has almost completely been replaced by lasers and digital processes. A commonly used technology for engraving screens, print and embossing forms in the printing industry, well known since then, is the use of RF-excited CO2 lasers with a beam power up to about 1 kW, modulated in accordance to the pattern to be engraved. Future needs for high-security printing (banknotes, security papers, passports, etc.) will require laser engraving of at least half a million or even more structured elements with a depth from some μm up to 500 μm. Industry now wants photorealistic pictures in packaging design, which requires a similar performance. To ensure 'trusted pulses' from the digital process to the print result the use of correlative microscopy (CLSM and SEM) is demonstrated as a complete chain for a correlative print process in this paper.

  14. Cavity-enhanced absorption spectroscopy with a ps-pulsed UV laser for sensitive, high-speed measurements in a shock tube.

    PubMed

    Wang, Shengkai; Sun, Kai; Davidson, David F; Jeffries, Jay B; Hanson, Ronald K

    2016-01-11

    We report the first application of cavity-enhanced absorption spectroscopy (CEAS) with a ps-pulsed UV laser for sensitive and rapid gaseous species time-history measurements in a transient environment (in this study, a shock tube). The broadband nature of the ps pulses enabled instantaneous coupling of the laser beam into roughly a thousand cavity modes, which grants excellent immunity to laser-cavity coupling noise in environments with heavy vibrations, even with an on-axis alignment. In this proof-of-concept experiment, we demonstrated an absorption gain of 49, which improved the minimum detectable absorbance by ~20 compared to the conventional single-pass strategy at similar experimental conditions. For absorption measurements behind reflected shock waves, an effective time-resolution of ~2 μs was achieved, which enabled time-resolved observations of transient phenomena, such as the vibrational relaxation of O(2) demonstrated here. The substantial improvement in detection sensitivity, together with microsecond measurement resolution implies excellent potential for studies of transient physical and chemical processes in nonequilibrium situations, particularly via measurements of weak absorptions of trace species in dilute reactive systems.

  15. High-speed tunable diode laser absorption spectroscopy for sampling-free in-cylinder water vapor concentration measurements in an optical IC engine

    NASA Astrophysics Data System (ADS)

    Witzel, O.; Klein, A.; Wagner, S.; Meffert, C.; Schulz, C.; Ebert, V.

    2012-11-01

    A novel, fiber-optic in situ laser hygrometer was developed to measure water vapor with microsecond time resolution directly inside an internal combustion (IC) engine. The instrument is intended for sampling-free quantification of recirculated exhaust gas in combustion engines. Direct tunable diode laser absorption spectroscopy was employed to allow absolute and self-calibrating H2O measurements. The compact and user-friendly instrument combines a fiber-coupled, 1.37 μm distributed feedback diode laser with kHz-fast, continuous wavelength scanning. Only small, typically 10 mm, optical access ports in the engine are needed. The new in situ hygrometer was tested via measurements in a motored optical research engine operated on ambient air, without any artificial humidification. Scanning the laser at 4 kHz resulted in a time resolution of 250 μs (i.e., 3° crank angle at 2,000 rpm), while the DC-coupled detector signals are digitized with a 4MSamples/s 16-bit data acquisition system. Absolute water vapor concentrations around 1 vol.% could be measured and quantified during the full compression stroke, i.e., over a pressure/temperature range of 0.07-0.52 MPa/300-500 K. Without any scan averaging or bandwidth filtering we could demonstrate signal-to-noise ratios between 51 (at p = 0.1 MPa) and 33 (at p = 0.4 MPa), which corresponds to H2O detection limits between 0.02 and 0.035 vol.% or length and bandwidth normalized detectivities of 285 and 477 ppb m Hz-½, respectively. Comparison of the dynamic H2O behavior during the compression stroke across several engine cycles and different operating conditions showed good reproducibility and absolute accuracy of the results, consistent with the boundary conditions, i.e., motored air operation. This new sensor therefore opens up new possibilities for engine cycle-resolved, calibration-free in situ AGR quantification and optimization in engine applications.

  16. High Speed Photometry for BUSCA

    NASA Astrophysics Data System (ADS)

    Cordes, O.; Reif, K.

    The camera BUSCA (Bonn University Simultaneous CAmera) is a standard instrument at the 2.2m telescope at Calar Alto Observatory (Spain) since 2001. At the moment some modifications of BUSCA are planned and partially realised. One major goal is the replacement of the old thick CCDs in the blue, yellow-green, and near-infrared channels. The newer CCDs have better cosmetics and performance in sensitivity. The other goal is to replace the old "Heidelberg"-style controller with a newly designed controller with the main focus on high-speed readout and on an advanced windowing mechanism. We present a theoretical analysis of the new controller design and its advantage in high speed photometry of rapidly pulsating stars. As an example PG1605+072 was chosen which was observed with BUSCA before in 2001 and 2002.

  17. High-speed rotorcraft propulsion

    NASA Technical Reports Server (NTRS)

    Rutherford, John W.; Fitzpatrick, Robert E.

    1991-01-01

    Recently completed high-speed rotorcraft design studies for NASA provide the basis to assess technology needs for the development of these aircraft. Preliminary analysis of several concepts possessing helicopter-like hover characteristics and cruise capabilities in the 450 knot regime, led to the selection of two concepts for further study. The concepts selected included the Rotor/Wing and the Tilt Wing. The two unique concepts use turbofan and turboshaft engines respectively. Designs, based on current technology for each, established a baseline configuration from which technology trade studies could be conducted. Propulsion technology goals from the IHPTET program established the advanced technolgy year. Due to high-speed requirements, each concept possesses its own unique propulsion challenges. Trade studies indicate that achieving th IHPTET Phase III goals significantly improves the effectiveness of both concepts. Increased engine efficiency is particularly important to VTOL aircraft by reducing gross weight.

  18. High-Speed Multiplexed Spatiotemporally Resolved Measurements of Exhaust Gas Recirculation Dynamics in a Multi-Cylinder Engine Using Laser Absorption Spectroscopy.

    PubMed

    Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E; Perfetto, Anthony; Geckler, Sam; Partridge, William P

    2016-04-01

    The need for more environmentally friendly and efficient energy conversion is of paramount importance in developing and designing next-generation internal combustion (IC) engines for transportation applications. One effective solution to reducing emissions of mono-nitrogen oxides (NOx) is exhaust gas recirculation (EGR), which has been widely implemented in modern vehicles. However, cylinder-to-cylinder and cycle-to-cycle variations in the charge-gas uniformity can be a major barrier to optimum EGR implementation on multi-cylinder engines, and can limit performance, stability, and efficiency. Precise knowledge and fine control over the EGR system is therefore crucial, particularly for optimizing advanced engine concepts such as reactivity controlled compression ignition (RCCI). An absorption-based laser diagnostic was developed to study spatiotemporal charge-gas distributions in an IC engine intake manifold in real-time. The laser was tuned to an absorption band of carbon dioxide (CO2), a standard exhaust-gas marker, near 2.7 µm. The sensor was capable of probing four separate measurement locations simultaneously, and independently analyzing EGR fraction at speeds of 5 kHz (1.2 crank-angle degree (CAD) at 1 k RPM) or faster with high accuracy. The probes were used to study spatiotemporal EGR non-uniformities in the intake manifold and ultimately promote the development of more efficient and higher performance engines.

  19. High-Speed and high-power vertical-cavity surface-emitting lasers based on InP suitable for telecommunication and gas sensing

    NASA Astrophysics Data System (ADS)

    Gruendl, Tobias; Zogal, Karolina; Mueller, Michael; Nagel, Robin D.; Jatta, Sandro; Geiger, Kathrin; Grasse, Christian; Boehm, Gerhard; Ortsiefer, Markus; Meyer, Ralf; Meissner, Peter; Amann, Markus-Christian

    2010-10-01

    We present 1.55 μm short-cavity buried-tunnel-junction VCSELs (Vertical-Cavity Surface-Emitting Lasers) with single mode output powers of 6.7 mW at 20°C and 3 mW at 80°C, respectively. Although the device had been predominantly optimized for high-power applications and a proper heat management, we are also observing a 3dB-cut-off frequency of more than 11 GHz and side mode suppression ratios (SMSRs) beyond 54 dB over the whole temperature range. The tuning range of the devices can be increased from 7 nm based on gain tuning to several tens of nanometers when replacing the top DBR by a micro-electro-mechanical system (MEMS) distributed Bragg reflector (DBR) composed of semiconductor or dielectric material being thermally actuated for changing the cavity length. These devices are perfectly suitable for telecommunication and gas sensing applications and represent outstanding devices for the so called tunable diode laser absorption spectroscopy (TDLAS) technique.

  20. High-Speed Multiplexed Spatiotemporally Resolved Measurements of Exhaust Gas Recirculation Dynamics in a Multi-Cylinder Engine Using Laser Absorption Spectroscopy

    DOE PAGES

    Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E.; ...

    2016-04-01

    The need for more environmentally friendly and efficient energy conversion is of paramount importance in developing and designing next-generation internal combustion (IC) engines for transportation applications. One effective solution to reducing emissions of mono-nitrogen oxides (NOx) is exhaust gas recirculation (EGR), which has been widely implemented in modern vehicles. However, cylinder-to-cylinder and cycle-to-cycle variations in the charge-gas uniformity can be a major barrier to optimum EGR implementation on multi-cylinder engines, and can limit performance, stability, and efficiency. Precise knowledge and fine control over the EGR system is thus crucial, particularly for optimizing advanced engine concepts such as reactivity controlled compressionmore » ignition (RCCI). An absorption-based laser diagnostic was developed to study spatiotemporal charge-gas distributions in an IC engine intake manifold in real-time. The laser was tuned to an absorption band of carbon dioxide (CO2), a standard exhaust-gas marker, near 2.7 µm. The sensor was capable of probing four separate measurement locations simultaneously, and independently analyzing EGR fraction at speeds of 5 kHz (1.2 crank-angle degree (CAD) at 1 k RPM) or faster with high accuracy. Lastly, the probes were used to study spatiotemporal EGR non-uniformities in the intake manifold and ultimately promote the development of more efficient and higher performance engines.« less

  1. High-Speed Multiplexed Spatiotemporally Resolved Measurements of Exhaust Gas Recirculation Dynamics in a Multi-Cylinder Engine Using Laser Absorption Spectroscopy

    SciTech Connect

    Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E.; Perfetto, Anthony; Geckler, Sam; Partridge, William P.

    2016-04-01

    The need for more environmentally friendly and efficient energy conversion is of paramount importance in developing and designing next-generation internal combustion (IC) engines for transportation applications. One effective solution to reducing emissions of mono-nitrogen oxides (NOx) is exhaust gas recirculation (EGR), which has been widely implemented in modern vehicles. However, cylinder-to-cylinder and cycle-to-cycle variations in the charge-gas uniformity can be a major barrier to optimum EGR implementation on multi-cylinder engines, and can limit performance, stability, and efficiency. Precise knowledge and fine control over the EGR system is thus crucial, particularly for optimizing advanced engine concepts such as reactivity controlled compression ignition (RCCI). An absorption-based laser diagnostic was developed to study spatiotemporal charge-gas distributions in an IC engine intake manifold in real-time. The laser was tuned to an absorption band of carbon dioxide (CO2), a standard exhaust-gas marker, near 2.7 µm. The sensor was capable of probing four separate measurement locations simultaneously, and independently analyzing EGR fraction at speeds of 5 kHz (1.2 crank-angle degree (CAD) at 1 k RPM) or faster with high accuracy. Lastly, the probes were used to study spatiotemporal EGR non-uniformities in the intake manifold and ultimately promote the development of more efficient and higher performance engines.

  2. High-speed code validation

    NASA Technical Reports Server (NTRS)

    Barnwell, Richard W.; Rogers, R. Clayton; Pittman, James L.; Dwoyer, Douglas L.

    1987-01-01

    The topics are presented in viewgraph form and include the following: NFL body experiment; high-speed validation problems; 3-D Euler/Navier-Stokes inlet code; two-strut inlet configuration; pressure contours in two longitudinal planes; sidewall pressure distribution; pressure distribution on strut inner surface; inlet/forebody tests in 60 inch helium tunnel; pressure distributions on elliptical missile; code validations; small scale test apparatus; CARS nonintrusive measurements; optimized cone-derived waverider study; etc.

  3. Focused Mission High Speed Combatant

    DTIC Science & Technology

    2003-05-09

    hull types to determine which hull type best meets the requirements for the Focused Mission High Speed Combatant. The first step in the analysis...MAPC, uses parametric models and scaling to create high level designs of various hull types. The inputs are desired speed , range, payload, sea state...reached 10 SWATH vessels exhibit superior seakeeping at near zero speed compared to other hull forms 5 Assumes 2 equal-sized GE Gas Turbines 11

  4. High-speed imaging system for observation of discharge phenomena

    NASA Astrophysics Data System (ADS)

    Tanabe, R.; Kusano, H.; Ito, Y.

    2008-11-01

    A thin metal electrode tip instantly changes its shape into a sphere or a needlelike shape in a single electrical discharge of high current. These changes occur within several hundred microseconds. To observe these high-speed phenomena in a single discharge, an imaging system using a high-speed video camera and a high repetition rate pulse laser was constructed. A nanosecond laser, the wavelength of which was 532 nm, was used as the illuminating source of a newly developed high-speed video camera, HPV-1. The time resolution of our system was determined by the laser pulse width and was about 80 nanoseconds. The system can take one hundred pictures at 16- or 64-microsecond intervals in a single discharge event. A band-pass filter at 532 nm was placed in front of the camera to block the emission of the discharge arc at other wavelengths. Therefore, clear images of the electrode were recorded even during the discharge. If the laser was not used, only images of plasma during discharge and thermal radiation from the electrode after discharge were observed. These results demonstrate that the combination of a high repetition rate and a short pulse laser with a high speed video camera provides a unique and powerful method for high speed imaging.

  5. High-Speed, Integrated Ablation Cell and Dual Concentric Injector Plasma Torch for Laser Ablation-Inductively Coupled Plasma Mass Spectrometry.

    PubMed

    Douglas, David N; Managh, Amy J; Reid, Helen J; Sharp, Barry L

    2015-11-17

    In recent years, laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) has gained increasing importance for biological analysis, where ultratrace imaging at micrometer resolution is required. However, while undoubtedly a valuable research tool, the washout times and sensitivity of current technology have restricted its routine and clinical application. Long periods between sampling points are required to maintain adequate spatial resolution. Additionally, temporal signal dispersion reduces the signal-to-noise ratio, which is a particular concern when analyzing discrete samples, such as individual particles or cells. This paper describes a novel, two-volume laser ablation cell and integrated ICP torch designed to minimize aerosol dispersion for fast, efficient sample transport. The holistic design utilizes a short, continuous diameter fused silica conduit, which extends from the point of ablation, through the ICP torch, and into the base of the plasma. This arrangement removes the requirement for a dispersive component for argon addition, and helps to keep the sample on axis with the ICP cone orifice. Hence, deposition of sample on the cones is theoretically reduced with a resulting improvement in the absolute sensitivity (counts per unit mole). The system described here achieved washouts of 1.5, 3.2, and 4.9 ms for NIST 612 glass, at full width half, 10%, and 1% maximum, respectively, with an 8-14-fold improvement in absolute sensitivity, compared to a single volume ablation cell. To illustrate the benefits of this performance, the system was applied to a contemporary bioanalytical challenge, specifically the analysis of individual biological cells, demonstrating similar improvements in performance.

  6. Using Concatenated Profiles from High-Speed Laser Profile Scanners to Estimate Debris-Flow Characteristics: A Novel Approach Based on Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Jacquemart, M. F.; Meier, L.; Graf, C.; Morsdorf, F.

    2015-12-01

    We use globally unique datasets from paired laser profile scanners to measure debris-flow height, velocity and discharge in two well-known debris-flow channels in Switzerland. Since 2011, these scanners have been scanning passing debris flows at rates of up to 75 Hz, acquiring millions of cross-bed profiles. The profiles can be concatenated through time, generating unique 2.5D representations of passing debris flows. Applying a large-scale Particle Image Velocimetry (PIV) approach to these datasets has proven successful to measure surface flow velocities. Flow height can also be estimated from the laser scanners, and thus a discharge estimate can be given. To account for changes to the channel bed due to erosion and deposition during the debris flow, we compute two flow height estimates using a pre-event as well as a post-event channel geometry in order to visualize discharge variability.Velocity outliers need to be excluded to provide reliable estimates of peak discharge, and changes to the channel bed are assumed to be the largest source of uncertainty. However, the latter problem is inherent to all debris-flow discharge measurements, and we have found the new system to offer distinct advantages over the conventional system relying on geophones and a radar gauge. The wide scan angle of up to 190° renders the scanners insensitive to changes of the flow path, and the point density of roughly 20 points per meter offer unprecedented spatial coverage.In addition, the geometries of the cross-bed profiles have been analyzed, revealing distinct changes of cross-flow convexity between the front and the tail of the flows in several cases. This is assumed to indicate changes of debris-flow mixtures, but further research is needed to better understand this signal.We hope that our preliminary analysis and toolbox will facilitate working with these kinds of datasets so as to further improve debris-flow understanding, monitoring and modeling efforts in the future.

  7. Unsupervised learning algorithm for high-speed defect detection in rails by laser/air-coupled non-contact ultrasonic testing

    NASA Astrophysics Data System (ADS)

    Rizzo, Piervincenzo; Coccia, Stefano; Lanza di Scalea, Francesco; Bartoli, Ivan; Fateh, Mahmood

    2006-03-01

    Recent train accidents and associated direct and indirect costs including cost of repair of equipment and infrastructure as well as delay and death/injury costs, have reaffirmed the need for developing rail defect detection systems more effective than those used today. In fact, rail defect detection has been identified as a priority area in the U.S. Federal Railroad Administration 5-year R&D plan. This paper proposes an unsupervised learning algorithm for defect detection in rails. The algorithm is used in a non-contact inspection system that is targeted to the detection of transverse-type cracks in the rail head (including transverse fissures and detail fractures), notoriously the most dangerous flaws in rails. The system uses ultrasonic guided waves that are generated by a pulsed laser and are detected by air-coupled sensors positioned as far away as 76 mm (3") from the top of rail head. The inspection ranges is at least 500 mm (20") for surface head cracks as shallow as 1 mm. Fast data output is achieved by processing the ultrasonic defect signatures by Wavelet Transform algorithms. The features extracted after wavelet processing are analyzed by a learning algorithm based on novelty detection. This algorithm attempts to detect the presence of damage despite the normal variations in ultrasonic signal features that may be found in a field test.

  8. Detection and isolation of rare cells by 2-step enrichment high-speed flow cytometry/cell sorting and single cell LEAP laser ablation

    NASA Astrophysics Data System (ADS)

    Zordan, M. D.; Leary, James F.

    2011-02-01

    The clonal isolation of rare cells, especially cancer and stem cells, in a population is important to the development of improved medical treatment. We have demonstrated that the Laser-Enabled Analysis and Processing (LEAP, Cyntellect Inc., San Diego, CA) instrument can be used to efficiently produce single cell clones by photoablative dilution. Additionally, we have also shown that cells present at low frequencies can be cloned by photoablative dilution after they are pre-enriched by flow cytometry based cell sorting. Circulating tumor cells were modeled by spiking isolated peripheral blood cells with cells from the lung carcinoma cell line A549. Flow cytometry based cell sorting was used to perform an enrichment sort of A549 cells directly into a 384 well plate. Photoablative dilution was performed with the LEAPTM instrument to remove any contaminating cells, and clonally isolate 1 side population cell per well. We were able to isolate and grow single clones of side population cells using this method at greater than 90% efficiency. We have developed a 2 step method that is able to perform the clonal isolation of rare cells based on a medically relevant functional phenotype.

  9. High speed quantitative digital microscopy

    NASA Technical Reports Server (NTRS)

    Castleman, K. R.; Price, K. H.; Eskenazi, R.; Ovadya, M. M.; Navon, M. A.

    1984-01-01

    Modern digital image processing hardware makes possible quantitative analysis of microscope images at high speed. This paper describes an application to automatic screening for cervical cancer. The system uses twelve MC6809 microprocessors arranged in a pipeline multiprocessor configuration. Each processor executes one part of the algorithm on each cell image as it passes through the pipeline. Each processor communicates with its upstream and downstream neighbors via shared two-port memory. Thus no time is devoted to input-output operations as such. This configuration is expected to be at least ten times faster than previous systems.

  10. A high speed sequential decoder

    NASA Technical Reports Server (NTRS)

    Lum, H., Jr.

    1972-01-01

    The performance and theory of operation for the High Speed Hard Decision Sequential Decoder are delineated. The decoder is a forward error correction system which is capable of accepting data from binary-phase-shift-keyed and quadriphase-shift-keyed modems at input data rates up to 30 megabits per second. Test results show that the decoder is capable of maintaining a composite error rate of 0.00001 at an input E sub b/N sub o of 5.6 db. This performance has been obtained with minimum circuit complexity.

  11. Flexible high-speed CODEC

    NASA Technical Reports Server (NTRS)

    Segallis, Greg P.; Wernlund, Jim V.; Corry, Glen

    1993-01-01

    This report is prepared by Harris Government Communication Systems Division for NASA Lewis Research Center under contract NAS3-25087. It is written in accordance with SOW section 4.0 (d) as detailed in section 2.6. The purpose of this document is to provide a summary of the program, performance results and analysis, and a technical assessment. The purpose of this program was to develop a flexible, high-speed CODEC that provides substantial coding gain while maintaining bandwidth efficiency for use in both continuous and bursted data environments for a variety of applications.

  12. High speed quantitative digital microscopy

    NASA Technical Reports Server (NTRS)

    Castleman, K. R.; Price, K. H.; Eskenazi, R.; Ovadya, M. M.; Navon, M. A.

    1984-01-01

    Modern digital image processing hardware makes possible quantitative analysis of microscope images at high speed. This paper describes an application to automatic screening for cervical cancer. The system uses twelve MC6809 microprocessors arranged in a pipeline multiprocessor configuration. Each processor executes one part of the algorithm on each cell image as it passes through the pipeline. Each processor communicates with its upstream and downstream neighbors via shared two-port memory. Thus no time is devoted to input-output operations as such. This configuration is expected to be at least ten times faster than previous systems.

  13. High-Speed TCP Testing

    NASA Technical Reports Server (NTRS)

    Brooks, David E.; Gassman, Holly; Beering, Dave R.; Welch, Arun; Hoder, Douglas J.; Ivancic, William D.

    1999-01-01

    Transmission Control Protocol (TCP) is the underlying protocol used within the Internet for reliable information transfer. As such, there is great interest to have all implementations of TCP efficiently interoperate. This is particularly important for links exhibiting long bandwidth-delay products. The tools exist to perform TCP analysis at low rates and low delays. However, for extremely high-rate and lone-delay links such as 622 Mbps over geosynchronous satellites, new tools and testing techniques are required. This paper describes the tools and techniques used to analyze and debug various TCP implementations over high-speed, long-delay links.

  14. Multiplexed broadband beam steering system utilizing high speed MEMS mirrors.

    PubMed

    Knoernschild, Caleb; Kim, Changsoon; Lu, Felix P; Kim, Jungsang

    2009-04-27

    We present a beam steering system based on micro-electromechanical systems technology that features high speed steering of multiple laser beams over a broad wavelength range. By utilizing high speed micromirrors with a broadband metallic coating, our system has the flexibility to simultaneously incorporate a wide range of wavelengths and multiple beams. We demonstrate reconfiguration of two independent beams at different wavelengths (780 and 635 nm) across a common 5x5 array with 4 micros settling time. Full simulation of the optical system provides insights on the scalability of the system. Such a system can provide a versatile tool for applications where fast laser multiplexing is necessary.

  15. High-speed optogenetic circuit mapping

    NASA Astrophysics Data System (ADS)

    Augustine, George J.; Chen, Susu; Gill, Harin; Katarya, Malvika; Kim, Jinsook; Kudolo, John; Lee, Li M.; Lee, Hyunjeong; Lo, Shun Qiang; Nakajima, Ryuichi; Park, Min-Yoon; Tan, Gregory; Tang, Yanxia; Teo, Peggy; Tsuda, Sachiko; Wen, Lei; Yoon, Su-In

    2013-03-01

    Scanning small spots of laser light allows mapping of synaptic circuits in brain slices from transgenic mice expressing channelrhodopsin-2 (ChR2). These light spots photostimulate presynaptic neurons expressing ChR2, while postsynaptic responses can be monitored in neurons that do not express ChR2. Correlating the location of the light spot with the amplitude of the postsynaptic response elicited at that location yields maps of the spatial organization of the synaptic circuits. This approach yields maps within minutes, which is several orders of magnitude faster than can be achieved with conventional paired electrophysiological methods. We have applied this high-speed technique to map local circuits in many brain regions. In cerebral cortex, we observed that maps of excitatory inputs to pyramidal cells were qualitatively different from those measured for interneurons within the same layers of the cortex. In cerebellum, we have used this approach to quantify the convergence of molecular layer interneurons on to Purkinje cells. The number of converging interneurons is reduced by treatment with gap junction blockers, indicating that electrical synapses between interneurons contribute substantially to the spatial convergence. Remarkably, gap junction blockers affect convergence in sagittal cerebellar slices but not in coronal slices, indicating sagittal polarization of electrical coupling between interneurons. By measuring limb movement or other forms of behavioral output, this approach also can be used in vivo to map brain circuits non-invasively. In summary, ChR2-mediated high-speed mapping promises to revolutionize our understanding of brain circuitry.

  16. Experiments on high speed ejectors

    NASA Technical Reports Server (NTRS)

    Wu, J. J.

    1986-01-01

    Experimental studies were conducted to investigate the flow and the performance of thrust augmenting ejectors for flight Mach numbers in the range of 0.5 to 0.8, primary air stagnation pressures up to 107 psig (738 kPa), and primary air stagnation temperatures up to 1250 F (677 C). The experiment verified the existence of the second solution ejector flow, where the flow after complete mixing is supersonic. Thrust augmentation in excess of 1.2 was demonstrated for both hot and cold primary jets. The experimental ejector performed better than the corresponding theoretical optimal first solution ejector, where the mixed flow is subsonic. Further studies are required to realize the full potential of the second solution ejector. The research program was started by the Flight Dynamics Research Corporation (FDRC) to investigate the characteristic of a high speed ejector which augments thrust of a jet at high flight speeds.

  17. High-speed data search

    NASA Technical Reports Server (NTRS)

    Driscoll, James N.

    1994-01-01

    The high-speed data search system developed for KSC incorporates existing and emerging information retrieval technology to help a user intelligently and rapidly locate information found in large textual databases. This technology includes: natural language input; statistical ranking of retrieved information; an artificial intelligence concept called semantics, where 'surface level' knowledge found in text is used to improve the ranking of retrieved information; and relevance feedback, where user judgements about viewed information are used to automatically modify the search for further information. Semantics and relevance feedback are features of the system which are not available commercially. The system further demonstrates focus on paragraphs of information to decide relevance; and it can be used (without modification) to intelligently search all kinds of document collections, such as collections of legal documents medical documents, news stories, patents, and so forth. The purpose of this paper is to demonstrate the usefulness of statistical ranking, our semantic improvement, and relevance feedback.

  18. Small Scale High Speed Turbomachinery

    NASA Technical Reports Server (NTRS)

    London, Adam P. (Inventor); Droppers, Lloyd J. (Inventor); Lehman, Matthew K. (Inventor); Mehra, Amitav (Inventor)

    2015-01-01

    A small scale, high speed turbomachine is described, as well as a process for manufacturing the turbomachine. The turbomachine is manufactured by diffusion bonding stacked sheets of metal foil, each of which has been pre-formed to correspond to a cross section of the turbomachine structure. The turbomachines include rotating elements as well as static structures. Using this process, turbomachines may be manufactured with rotating elements that have outer diameters of less than four inches in size, and/or blading heights of less than 0.1 inches. The rotating elements of the turbomachines are capable of rotating at speeds in excess of 150 feet per second. In addition, cooling features may be added internally to blading to facilitate cooling in high temperature operations.

  19. Flexible High Speed Codec (FHSC)

    NASA Technical Reports Server (NTRS)

    Segallis, G. P.; Wernlund, J. V.

    1991-01-01

    The ongoing NASA/Harris Flexible High Speed Codec (FHSC) program is described. The program objectives are to design and build an encoder decoder that allows operation in either burst or continuous modes at data rates of up to 300 megabits per second. The decoder handles both hard and soft decision decoding and can switch between modes on a burst by burst basis. Bandspreading is low since the code rate is greater than or equal to 7/8. The encoder and a hard decision decoder fit on a single application specific integrated circuit (ASIC) chip. A soft decision applique is implemented using 300 K emitter coupled logic (ECL) which can be easily translated to an ECL gate array.

  20. High speed sampler and demultiplexer

    DOEpatents

    McEwan, T.E.

    1995-12-26

    A high speed sampling demultiplexer based on a plurality of sampler banks, each bank comprising a sample transmission line for transmitting an input signal, a strobe transmission line for transmitting a strobe signal, and a plurality of sampling gates at respective positions along the sample transmission line for sampling the input signal in response to the strobe signal. Strobe control circuitry is coupled to the plurality of banks, and supplies a sequence of bank strobe signals to the strobe transmission lines in each of the plurality of banks, and includes circuits for controlling the timing of the bank strobe signals among the banks of samplers. Input circuitry is included for supplying the input signal to be sampled to the plurality of sample transmission lines in the respective banks. The strobe control circuitry can repetitively strobe the plurality of banks of samplers such that the banks of samplers are cycled to create a long sample length. Second tier demultiplexing circuitry is coupled to each of the samplers in the plurality of banks. The second tier demultiplexing circuitry senses the sample taken by the corresponding sampler each time the bank in which the sampler is found is strobed. A plurality of such samples can be stored by the second tier demultiplexing circuitry for later processing. Repetitive sampling with the high speed transient sampler induces an effect known as ``strobe kickout``. The sample transmission lines include structures which reduce strobe kickout to acceptable levels, generally 60 dB below the signal, by absorbing the kickout pulses before the next sampling repetition. 16 figs.

  1. High speed sampler and demultiplexer

    DOEpatents

    McEwan, Thomas E.

    1995-01-01

    A high speed sampling demultiplexer based on a plurality of sampler banks, each bank comprising a sample transmission line for transmitting an input signal, a strobe transmission line for transmitting a strobe signal, and a plurality of sampling gates at respective positions along the sample transmission line for sampling the input signal in response to the strobe signal. Strobe control circuitry is coupled to the plurality of banks, and supplies a sequence of bank strobe signals to the strobe transmission lines in each of the plurality of banks, and includes circuits for controlling the timing of the bank strobe signals among the banks of samplers. Input circuitry is included for supplying the input signal to be sampled to the plurality of sample transmission lines in the respective banks. The strobe control circuitry can repetitively strobe the plurality of banks of samplers such that the banks of samplers are cycled to create a long sample length. Second tier demultiplexing circuitry is coupled to each of the samplers in the plurality of banks. The second tier demultiplexing circuitry senses the sample taken by the corresponding sampler each time the bank in which the sampler is found is strobed. A plurality of such samples can be stored by the second tier demultiplexing circuitry for later processing. Repetitive sampling with the high speed transient sampler induces an effect known as "strobe kickout". The sample transmission lines include structures which reduce strobe kickout to acceptable levels, generally 60 dB below the signal, by absorbing the kickout pulses before the next sampling repetition.

  2. High Speed Photography In The United Kingdom

    NASA Astrophysics Data System (ADS)

    Lunn, George H.

    1989-06-01

    At the 13th Congress in Tokyo, I presented a paper with this title in which some early history was mentioned followed by a more detailed study of the activities of the main research groups in Britain from the period between 1950 and 1978. On this occasion, some early topics will be mentioned. The period since 1978 has seen quite a few changes in that research is now more in the hands of commercial groups as opposed to the previous governmental laboratories. It is true that the pricipal camera systems have reached towards their physical limits. However other new techniques are still expanding, for example, Lasers, Holography and Videography. The new systems are principally in the hands of major or specialist companies with the offical and industrial research groups using their products. The Association for High Speed Photography continues to encourage both researchers and users by providing oportunities for users, suppliers and manufacturers to meet and discuss.

  3. High-speed multichannel optical switching

    SciTech Connect

    Mikaelian, A.L.; Salakhutdinov, V.K.

    1994-12-31

    The programmable interconnection between N input and N output channels based on a matrix of microholograms is considered. Such a system can be used for optical switching having high speed, about gigabits-per-second. An example of such a system using bacteriorhodopsin film is investigated both theoretically and experimentally. The thickness of bacteriorhodopsin was 50 {micro}m and the cell size 3cmx2cm. To maintain interconnects each microhologram was regenerated by means of a routing system composed of a He-Ne laser, deflectors and optical elements. Experimentally, 20 channels were used. The diameter of the microhologram was 1 mm, and the diffraction efficiency was about 2%. The tests and calculations show the possibility of arranging 10{sup 4} switching channels with speed about 1 gigabit per second.

  4. Very high-speed digital holography

    NASA Astrophysics Data System (ADS)

    Pérez López, Carlos; Mendoza Santoyo, Fernando; Rodríguez Vera, Ramón; Moreno, David; Barrientos, Bernardino

    2006-08-01

    It is reported for the first time the use of a high speed camera in digital holography with an out of plane sensitivity. The camera takes the image plane holograms of a cw laser illuminated rectangular framed polyester material at a rate of 5000 per second, that is a spacing of 200 microseconds between holograms, and 512 by 500 pixels at 10 bit resolution. The freely standing object has a random movement due to non controlled environmental air currents. As is usual with this technique each digital hologram is Fourier processed in order to obtain upon comparison with a consecutive digital hologram the phase map of the displacement. High quality results showing the amplitude and direction of the random movement are presented.

  5. Very high speed cw digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Pérez-López, Carlos; de La Torre-Ibarra, Manuel H.; Mendoza Santoyo, Fernando

    2006-10-01

    It is reported for the first time the use of a very high speed camera in digital holographic interferometry with an out of plane sensitivity setup. The image plane holograms of a spherical latex balloon illuminated by a cw laser were acquired at a rate of 4000 frames per second, representing a time spacing between holograms of 250 microseconds, for 512 × 512 pixels at 8 bits resolution. Two types of tests were accomplished for a proof of principle of the technique, one with no constrains on the object which meant random movements due to non controlled environmental air currents, and the other with specific controlled conditions on the object. Results presented correspond to a random sample of sequential digital holograms, chosen from a 1 second exposure, individually Fourier processed in order to perform the usual comparison by subtraction between consecutive pairs thus obtaining the phase map of the object out of plane displacement, shown as a movie.

  6. A new design for a high speed spindle

    SciTech Connect

    Weck, M.; Fischer, S.; Holster, P.; Carlisle, K.; Chen, Y.

    1996-12-31

    Precision grinding and micromachining both impose high demands on the machine behavior, since the achievable workpiece accuracy is determined not only by the technological parameters but also by the characteristics of the applicated machine components. Ultraprecision surface quality and the mechanical fabrication of structures in the micron range can only be achieved by using machine tools which have appropriate spindles. Structures cannot be manufactured using spindle types of which the radial error motion is greater than the level of contour accuracy or surface roughness required. In addition, the spindle speed is an important value. Not only a certain cutting speed is needed from the technological point of view, but also the machining time required for microstructuring surfaces is reduced by deploying a high frequency spindle, thereby increasing the economic efficiency of the technique. Hence, the main purpose of the project was to develop a high speed spindle with properties concerning accuracy, speed and stiffness beyond commercially available ones.

  7. Preliminary study of high-speed machining

    SciTech Connect

    Jordan, R.E.

    1980-07-01

    The feasibility of a high speed machining process has been established for application to Bendix aluminum products, based upon information gained through visits to existing high speed machining facilities and by the completion of a representative Bendix part using this process. The need for an experimental high speed machining capability at Bendix for further process evaluation is established.

  8. Micromachined Dust Traps

    NASA Technical Reports Server (NTRS)

    Bearman, Gregory H.; Bradley, James G.

    1993-01-01

    Micromachined traps devised to capture dust particles for analysis without contaminating them. Based on micromachined structures retaining particles, rather than adhesives or greases interfering with scanning-electron-microscope analysis or x-ray imaging. Unlike maze traps and traps enmeshing particles in steel wool or similar materials, micromachined traps do not obscure trapped particles. Internal geometries of traps range from simple cones to U-shapes, all formed by etching silicon.

  9. Hypereutectoid high-speed steels

    SciTech Connect

    Kremnev, L.S.

    1986-01-01

    Half of the tungsten and molybdenum contained in R6M5 and R18 steels is concentrated in the undissolved eutectic carbides hindering austenitic grain gowth in hardening and providing the necessary strength and impact strength. This article describes the tungsten-free low-alloy high-speed steel 11M5F with a chemical composition of 1.03-1.10% C, 5.2-5.7% Mo, 3.8-4.2% Cr, 1.3-1.7% V, 0.3-0.6% Si, and 0.3% Ce. The properties of 11M5F and R6M5 steels are examined and compared. The results of production and laboratory tests of the cutting properties of tools of the steels developed showed their high effectiveness, especially of 11M5F steel with 1% A1. The life of tools of the tungsten-free steels is two or three times greater than the life of tools of R6M5 steel.

  10. 8-Foot High Speed Tunnel

    NASA Technical Reports Server (NTRS)

    1936-01-01

    Control panel below the test section of the 8-Foot High Speed Tunnel (8-Foot HST). Authorized July 17, 1933, construction of the 8-Foot HST was paid for with funds from the Federal Public Works Administration. Manly Hood and Russell Robinson designed the unusual facility which could produce a 500 mph wind stream across an 8-Foot test section. The concrete shell was not part of the original design. Like most projects funded through New Deal programs, the PWA restricted the amount of money which could be spent on materials. The majority of funds were supposed to be expended on labor. Though originally, Hood and Robinson had planned a welded steel pressure vessel around the test section, PWA officials proposed the idea of concrete. This picture shows the test section inside the igloo-like structure with walls of 1-foot thick reinforced concrete. The thick walls were needed 'because of the Bernoulli effect, [which meant that] the text chamber had to withstand powerful, inwardly directed pressure. Operating personnel located inside the igloo were subjected to pressures equivalent to 10,000-foot altitude and had to wear oxygen masks and enter through airlocks. A heat exchanger removed the large quantities of heat generated by the big fan.'

  11. High speed imager test station

    DOEpatents

    Yates, G.J.; Albright, K.L.; Turko, B.T.

    1995-11-14

    A test station enables the performance of a solid state imager (herein called a focal plane array or FPA) to be determined at high image frame rates. A programmable waveform generator is adapted to generate clock pulses at determinable rates for clock light-induced charges from a FPA. The FPA is mounted on an imager header board for placing the imager in operable proximity to level shifters for receiving the clock pulses and outputting pulses effective to clock charge from the pixels forming the FPA. Each of the clock level shifters is driven by leading and trailing edge portions of the clock pulses to reduce power dissipation in the FPA. Analog circuits receive output charge pulses clocked from the FPA pixels. The analog circuits condition the charge pulses to cancel noise in the pulses and to determine and hold a peak value of the charge for digitizing. A high speed digitizer receives the peak signal value and outputs a digital representation of each one of the charge pulses. A video system then displays an image associated with the digital representation of the output charge pulses clocked from the FPA. In one embodiment, the FPA image is formatted to a standard video format for display on conventional video equipment. 12 figs.

  12. High speed imager test station

    DOEpatents

    Yates, George J.; Albright, Kevin L.; Turko, Bojan T.

    1995-01-01

    A test station enables the performance of a solid state imager (herein called a focal plane array or FPA) to be determined at high image frame rates. A programmable waveform generator is adapted to generate clock pulses at determinable rates for clock light-induced charges from a FPA. The FPA is mounted on an imager header board for placing the imager in operable proximity to level shifters for receiving the clock pulses and outputting pulses effective to clock charge from the pixels forming the FPA. Each of the clock level shifters is driven by leading and trailing edge portions of the clock pulses to reduce power dissipation in the FPA. Analog circuits receive output charge pulses clocked from the FPA pixels. The analog circuits condition the charge pulses to cancel noise in the pulses and to determine and hold a peak value of the charge for digitizing. A high speed digitizer receives the peak signal value and outputs a digital representation of each one of the charge pulses. A video system then displays an image associated with the digital representation of the output charge pulses clocked from the FPA. In one embodiment, the FPA image is formatted to a standard video format for display on conventional video equipment.

  13. ADVANCED HIGH SPEED PROGRAMMABLE PREFORMING

    SciTech Connect

    Norris Jr, Robert E; Lomax, Ronny D; Xiong, Fue; Dahl, Jeffrey S; Blanchard, Patrick J

    2010-01-01

    Polymer-matrix composites offer greater stiffness and strength per unit weight than conventional materials resulting in new opportunities for lightweighting of automotive and heavy vehicles. Other benefits include design flexibility, less corrosion susceptibility, and the ability to tailor properties to specific load requirements. However, widespread implementation of structural composites requires lower-cost manufacturing processes than those that are currently available. Advanced, directed-fiber preforming processes have demonstrated exceptional value for rapid preforming of large, glass-reinforced, automotive composite structures. This is due to process flexibility and inherently low material scrap rate. Hence directed fiber performing processes offer a low cost manufacturing methodology for producing preforms for a variety of structural automotive components. This paper describes work conducted at the Oak Ridge National Laboratory (ORNL), focused on the development and demonstration of a high speed chopper gun to enhance throughput capabilities. ORNL and the Automotive Composites Consortium (ACC) revised the design of a standard chopper gun to expand the operational envelope, enabling delivery of up to 20kg/min. A prototype unit was fabricated and used to demonstrate continuous chopping of multiple roving at high output over extended periods. In addition fiber handling system modifications were completed to sustain the high output the modified chopper affords. These hardware upgrades are documented along with results of process characterization and capabilities assessment.

  14. Quiet High-Speed Fan

    NASA Technical Reports Server (NTRS)

    Lieber, Lysbeth; Repp, Russ; Weir, Donald S.

    1996-01-01

    A calibration of the acoustic and aerodynamic prediction methods was performed and a baseline fan definition was established and evaluated to support the quiet high speed fan program. A computational fluid dynamic analysis of the NASA QF-12 Fan rotor, using the DAWES flow simulation program was performed to demonstrate and verify the causes of the relatively poor aerodynamic performance observed during the fan test. In addition, the rotor flowfield characteristics were qualitatively compared to the acoustic measurements to identify the key acoustic characteristics of the flow. The V072 turbofan source noise prediction code was used to generate noise predictions for the TFE731-60 fan at three operating conditions and compared to experimental data. V072 results were also used in the Acoustic Radiation Code to generate far field noise for the TFE731-60 nacelle at three speed points for the blade passage tone. A full 3-D viscous flow simulation of the current production TFE731-60 fan rotor was performed with the DAWES flow analysis program. The DAWES analysis was used to estimate the onset of multiple pure tone noise, based on predictions of inlet shock position as a function of the rotor tip speed. Finally, the TFE731-60 fan rotor wake structure predicted by the DAWES program was used to define a redesigned stator with the leading edge configured to minimize the acoustic effects of rotor wake / stator interaction, without appreciably degrading performance.

  15. High-speed pressure clamp.

    PubMed

    Besch, Stephen R; Suchyna, Thomas; Sachs, Frederick

    2002-10-01

    We built a high-speed, pneumatic pressure clamp to stimulate patch-clamped membranes mechanically. The key control element is a newly designed differential valve that uses a single, nickel-plated piezoelectric bending element to control both pressure and vacuum. To minimize response time, the valve body was designed with minimum dead volume. The result is improved response time and stability with a threefold decrease in actuation latency. Tight valve clearances minimize the steady-state air flow, permitting us to use small resonant-piston pumps to supply pressure and vacuum. To protect the valve from water contamination in the event of a broken pipette, an optical sensor detects water entering the valve and increases pressure rapidly to clear the system. The open-loop time constant for pressure is 2.5 ms for a 100-mmHg step, and the closed-loop settling time is 500-600 micros. Valve actuation latency is 120 micros. The system performance is illustrated for mechanically induced changes in patch capacitance.

  16. Magneto-optical system for high speed real time imaging

    NASA Astrophysics Data System (ADS)

    Baziljevich, M.; Barness, D.; Sinvani, M.; Perel, E.; Shaulov, A.; Yeshurun, Y.

    2012-08-01

    A new magneto-optical system has been developed to expand the range of high speed real time magneto-optical imaging. A special source for the external magnetic field has also been designed, using a pump solenoid to rapidly excite the field coil. Together with careful modifications of the cryostat, to reduce eddy currents, ramping rates reaching 3000 T/s have been achieved. Using a powerful laser as the light source, a custom designed optical assembly, and a high speed digital camera, real time imaging rates up to 30 000 frames per seconds have been demonstrated.

  17. Magneto-optical system for high speed real time imaging.

    PubMed

    Baziljevich, M; Barness, D; Sinvani, M; Perel, E; Shaulov, A; Yeshurun, Y

    2012-08-01

    A new magneto-optical system has been developed to expand the range of high speed real time magneto-optical imaging. A special source for the external magnetic field has also been designed, using a pump solenoid to rapidly excite the field coil. Together with careful modifications of the cryostat, to reduce eddy currents, ramping rates reaching 3000 T/s have been achieved. Using a powerful laser as the light source, a custom designed optical assembly, and a high speed digital camera, real time imaging rates up to 30 000 frames per seconds have been demonstrated.

  18. High-speed pulse-shape generator, pulse multiplexer

    DOEpatents

    Burkhart, Scott C.

    2002-01-01

    The invention combines arbitrary amplitude high-speed pulses for precision pulse shaping for the National Ignition Facility (NIF). The circuitry combines arbitrary height pulses which are generated by replicating scaled versions of a trigger pulse and summing them delayed in time on a pulse line. The combined electrical pulses are connected to an electro-optic modulator which modulates a laser beam. The circuit can also be adapted to combine multiple channels of high speed data into a single train of electrical pulses which generates the optical pulses for very high speed optical communication. The invention has application in laser pulse shaping for inertial confinement fusion, in optical data links for computers, telecommunications, and in laser pulse shaping for atomic excitation studies. The invention can be used to effect at least a 10.times. increase in all fiber communication lines. It allows a greatly increased data transfer rate between high-performance computers. The invention is inexpensive enough to bring high-speed video and data services to homes through a super modem.

  19. Surface Damage Growth Mitigation on KDP/DKDP Optics Using Single-Crystal Diamond Micro-Machining

    SciTech Connect

    Hrubesh, L; Adams, J; Feit, M; Sell, W; Stanley, J; Miller, E; Thompson, S; Whitman, P; Hackel, R

    2003-11-12

    A process whereby laser-initiated surface damage on KDP/DKDP optics is removed by spot micro-machining using a high-speed drill and a single-crystal diamond bit, is shown to mitigate damage growth for subsequent laser shots. Our tests show that machined dimples on both surfaces of an AR coated doubler (KDP) crystal are stable, for 526nm, {approx} 3.2ns pulses at {approx} 12J/cm{sup 2} fluences. Other tests also confirmed that the machined dimples on both surfaces of an AR coated tripler (DKDP) crystal are stable, for 351nm, {approx} 3ns pulses at {approx} 8J/cm{sup 2}. We have demonstrated successful mitigation of laser-initiated surface damage sites as large as 0.14mm diameter on DKDP, for up to 1000 shots at 351nm, 13J/cm{sup 2}, {approx} 11ns pulse length, and up to 10 shots at 351nm, 8J/cm{sup 2}, 3ns. Details of the method are presented, including estimates for the heat generated during micro-machining and a plan to implement this method to treat pre-initiated or retrieved-from-service, large-scale optics for use in high-peak-power laser applications.

  20. 850-nm Zn-diffusion vertical-cavity surface-emitting lasers with with oxide-relief structure for high-speed and energy-efficient optical interconnects from very-short to medium (2km) reaches

    NASA Astrophysics Data System (ADS)

    Shi, Jin-Wei; Wei, Chia-Chien; Chen, Jason (Jyehong); Yang, Ying-Jay

    2015-03-01

    High-speed and "green" ~850 nm vertical-cavity surface-emitting lasers (VCSELs) have lately attracted lots of attention due to their suitability for applications in optical interconnects (OIs). To further enhance the speed and its maximum allowable linking distance of VCSELs are two major trends to meet the requirement of OI in next generation data centers. Recently, by use of the advanced 850 nm VCSEL technique, data rate as high as 64 Gbit/sec over 57m and 20 Gbit/sec over 2km MMF transmission have been demonstrated, respectively. Here, we will review our recent work about 850 nm Zn-diffusion VCSELs with oxide-relief apertures to further enhance the above-mentioned performances. By using Zn-diffusion, we can not only reduce the device resistance but also manipulate the number of optical modes to benefit transmission. Combing such device, which has excellent single-mode (SMSR >30 dB) and high-power (~7mW) performance, with advanced modulation format (OFDM), record-high bit-rate-distance-product through MMF (2.3 km×28 Gbit/sec) has been demonstrated. Furthermore, by selective etching away the oxide aperture inside Zn-diffusion VCSEL, significant enhancement of device speed, D-factor, and reliability can be observed. With such unique VCSEL structure, >40 Gbit/sec energy-efficient transmission over 100m MMF under extremely low-driving current density (<10kA/cm2) has been successfully demonstrated.