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  • richardmitnick 5:46 am on April 21, 2016 Permalink | Reply
    Tags: , Laser Technology, ,   

    From Stanford: “Peering deep into materials with ultrafast science” 

    Stanford University Name
    Stanford University

    March 31, 2016 [Just appeared in social media]
    Glenn Roberts Jr.

    New techniques developed at SLAC and Stanford allow scientists to observe changes at the nanoscale that occur in fractions of a second in response to light. This artist’s conception depicts the first step in the photovoltaic response that light produces in lead titanate.

    Laser light exposes the properties of materials used in batteries and electronics

    Creating the batteries or electronics of the future requires understanding materials that are just a few atoms thick and that change their fundamental physical properties in fractions of a second. Cutting-edge facilities at SLAC National Accelerator Laboratory and Stanford University have allowed researchers like Aaron Lindenberg to visualize properties of these nanoscale materials at ultrafast time scales.

    In one experiment, a team led by Lindenberg showed atoms shifting in trillionths of a second to produce a wrinkle in a 3-atom-thick sample of a material that might someday be used in flexible electronics. Another study observed semiconductor crystals — called “quantum dots” because they defy classical physics at the nanoscale — expand and shrink in response to ultrafast pulses of laser light.

    A three-atom-thick material wrinkles in response to a laser pulse. Understanding these dynamic ripples could provide crucial clues for the development of next-generation solar cells, electronics and catalysts.

    Revealing such intriguing properties at the nanoscale gives clues about the fundamental nature of materials and how they perform in applications we rely on for energy or information.

    “Even though some of these materials are completely embedded in everyday technologies, not a lot is understood about how they work,” says Lindenberg, who is an associate professor of materials science and engineering and of photon science. He is also a principal investigator for two SLAC/Stanford joint institutes — Stanford Institute for Materials and Energy Sciences and Stanford PULSE Institute.

    “Part of the reason some phenomena are not well understood is because they happen so fast – in billionths, trillionths or even quadrillionths of a second. For the first time, we have tools that allow us to see these things,” he says.

    Working at the intersection of materials science and engineering, Lindenberg and his team have a particular focus on finding promising materials for next-generation electronics, light-based data storage technologies and energy applications.

    “There are a broad range of new properties that emerge at the nanoscale,” Lindenberg says. “The tiniest samples, with just tens or hundreds of atoms, can have nearly flawless structures that make them ideal test tubes for very fundamental questions about what happens when a material transforms.”

    The team uses different types of laser light at SLAC and Stanford labs to learn how simple tweaks in the size, shape and design of materials can change their basic properties in unexpected ways, which could lead to new applications. Taking advantage of the powerful X-rays at SLAC facilities, including the Linac Coherent Light Source [LCLS] and the Stanford Synchrotron Radiation Lightsource [SSRL] , they explore ultrafast changes in nanoscale samples.



    “We are trying to understand how electrons or atoms move in materials, which in turn determines, for example, the efficiency of solar cells and other energy-related materials, and how materials switch between different forms,” he says. “Ultrafast techniques allow you to see these kinds of things in a completely new way.”

    See the full article here .

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    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 1:53 pm on January 26, 2016 Permalink | Reply
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    From PPPL: “PPPL team wins 80 million processor hours on nation’s fastest supercomputer” 


    January 26, 2016
    John Greenwald

    The U.S Department of Energy (DOE) has awarded a total of 80 million processor hours on the fastest supercomputer in the nation to an astrophysical project based at the DOE’s Princeton Plasma Physics Laboratory (PPPL). The grants will enable researchers led by Amitava Bhattacharjee, head of the Theory Department at PPPL, and physicist Will Fox to study the dynamics of magnetic fields in the high-energy density plasmas that lasers create. Such plasmas can closely approximate those that occur in some astrophysical objects.

    The awards consist of 35 million hours from the INCITE (Innovative and Novel Impact on Computational Theory and Experiment) program, and 45 million hours from the ALCC, (ASCR — Advanced Scientific Computing Research — Leadership Computing Challenge.) Both will be carried out on the Titan Cray XK7 supercomputer at Oak Ridge National Laboratory. This work is supported by the DOE Office of Science.

    ORNL Titan Supercomputer
    Titan Cray XK7 supercomputer

    The combined research will shed light on large-scale magnetic behavior in space and will help design three days of experiments in 2016 and 2017 on the world’s most powerful high-intensity lasers at the National Ignition Facility (NIF) at the DOE’s Lawrence Livermore National Laboratory.

    Livermore NIF Banner
    Livermore NIF

    “This will enable us to do experiments in a regime not yet accessible with any other laboratory plasma device,” Bhattacharjee said.

    The supercomputer modeling, which is already under way, will investigate puzzles including:

    Magnetic field formation. The research will study Weibel instabilities, the process by which non-magnetic plasmas merge in space to produce magnetic fields. Understanding this phenomena, which takes place throughout the universe but has proven difficult to observe, can provide insight into the creation of magnetic fields in stars and galaxies.

    Magnetic field growth. Another mystery is how small-scale fields can evolve into large ones. The team will model a process called the Biermann battery, which amplifies the small fields through an unknown mechanism, and will attempt to decipher it.

    Explosive magnetic reconnection. The simulations will study still another process called plasmoid instabilities that have been widely theorized. These instabilities are believed to play an important role in producing super high-energy plasma particles when magnetic field lines that have separated violently reconnect.

    The NIF experiments will test these models and build upon the team’s work at the Laboratory for Laser Energetics at the University of Rochester. Researchers there have used high-intensity lasers at the university’s OMEGA EP facility to produce high-energy density plasmas and their magnetic fields.

    At NIF, the lasers will have 100 times the power of the Rochester facility and will produce plasmas that more closely match those that occur in space. The PPPL experiments will therefore focus on how reconnection proceeds in such large regimes.

    Joining Bhattacharjee and Fox on the INCITE award will be astrophysicists Kai Germaschewksi of the University of New Hampshire and Yi-Min Huang of PPPL. The same team is conducting the ALCC research with the addition of Jonathan Ng of Princeton University. Researchers on the NIF experiments, for which Fox is principal investigator, will include Bhattacharjee and collaborators from PPPL, Princeton, the universities of Rochester, Michigan and Colorado-Boulder, and NIF and the Lawrence Livermore National Laboratory.

    See the full article here .

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    Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

  • richardmitnick 8:24 pm on January 25, 2016 Permalink | Reply
    Tags: , HAPLS, Laser Technology,   

    From LLNL: “Petawatt laser system passes a key milestone” 

    Lawrence Livermore National Laboratory

    Jan. 22, 2016
    Breanna Bishop

    HAPLS  High-Repetition-Rate Advanced Petawatt Laser System LLNL
    This computer-aided design shows HAPLS’ two interconnected Livermore-developed laser systems. The diode-pumped, solid-state laser will deliver up to 200 joules of energy at a repetition rate of 10 Hz. At the pump laser output, a frequency converter doubles the laser frequency from infrared to green. The solid-state, short-pulse laser converts the energy from the pump laser to 30-joule, 30-femtosecond pulses for a peak power exceeding one petawatt. The laser system measures 4.6 meters wide and 17 meters long.

    The High-Repetition-Rate Advanced Petawatt Laser System (HAPLS) under construction at LLNL recently achieved a key average power milestone more than two months ahead of schedule, and is now moving into the next phase in its development.

    The HAPLS high-energy diode-pumped solid-state pump laser, firing at a repetition rate of 3.3 Hz (3.3 shots per second), achieved 70 joules of infrared (1,053-nanometer) energy and 39 joules of green (527-nm) energy. Completion of this average-power milestone marks another major step in the HAPLS commissioning plan: the beginning of the integration of the pump laser with the HAPLS high-energy short-pulse beamline.

    “Ramping the pump laser to this intermediary performance level was an important step for HAPLS,” said Constantin Haefner, program director for Advanced Photon Technologies. “For the first time we ran the pump laser at significant energy and average power levels, meeting and exceeding the required goals for this milestone. This accomplishment required a huge team effort and the team worked extremely hard to make this happen.

    “We are taking a risk-balanced approach in ramping HAPLS to its full performance. The data we collected confirmed our performance models and gave the green light to start integration with the short-pulse beamline before ramping to even higher power levels.”

    Representatives from the European Union’s Extreme Light Infrastructure Beamlines (ELI-Beamlines) facility in the Czech Republic, where HAPLS will be installed, attended the demonstration. “We are delighted to see the HAPLS pump laser work with a performance exceeding the project expectations for this phase, and achieve this important milestone on budget and ahead of schedule,” said ELI Beamlines Chief Laser Scientist Bedrich Rus. “The partnership with LLNL has been a tremendously successful story, and this demonstration shows the robustness of the underlying design and technology. The L3 (HAPLS) beamline will be an ELI Beamlines’ user facility workhorse.”

    HAPLS is designed to reach a peak power exceeding one petawatt at a repetition rate of 10 times per second to deliver intensities on target up to 1023 watts per square centimeter. Achieving this intensity would open up entirely new areas of laser–matter investigation, enable new applications of laser-driven X rays and particles, and for the first time allow researchers to study laser interactions with the sea of virtual particles that comprise a vacuum.

    Ramping of the laser to its full performance has been organized in several phases. The first phase, completed last October, brought the pump laser to an intermediate performance level in a “single shot” regime, as opposed to an average power regime in which the amplifiers are thermally loaded. “In the second phase,” Haefner said, “we brought it up to average power, and that was an intermediate performance level. And now we’re integrating the pump laser and the short-pulse system. Together with ELI Beamlines we will integrate the short-pulse performance diagnostics, and then we will ramp the short-pulse laser system, similar to what we did for the pump laser system, first to energy and then to average power.”

    “The reason for the phased approach,” said Systems Architect and Commissioning Manager Andy Bayramian, “is that we operate the laser at the intermediate performance level, learn how to operate it, identify operational challenges and input-data errors if they exist, and once we have gained operational experience, then we ramp it to its full performance.”

    The engineering of the HAPLS laser combines many disciplines to produce a high-quality design. Electrical, mechanical, optical, precision, controls, vacuum and infrastructure engineering teams have contributed to deliver the required components for a fully functional laser.

    HAPLS is designed to allow for future upgrades and scaling to even higher energies and repetition rates, which will ensure the longevity and scientific competitiveness of the ELI Beamlines facility.

    “HAPLS will allow its users for the first time to approach the commercial applications arena for laser-generated secondary sources,” Haefner said. “There’s no other laser which actually can produce sufficient average power of the high-intensity light required for commercial applications.”

    The system’s pulses will be used to generate extremely bright and short X-ray pulses for imaging cells and proteins at unprecedented spatial and temporal resolution. Another application is generating bunches of protons or ions for medical therapy and materials science research. Scientists also will study the interaction of intense laser light with matter to improve understanding of high energy density science.

    See the full article here .

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    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security
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  • richardmitnick 1:23 pm on December 28, 2015 Permalink | Reply
    Tags: , Cave studies, , Laser Technology, Lidar technology   

    From Eos: “Laser Beams Brighten Prospects for Cave Science” 

    Eos news bloc


    7 December 2015
    JoAnna Wendel

    Ben Shinabery (right), a land surveyor in Louisville, Ky., stands in Big Bat Cave with a volunteer and a lidar scanner sitting atop a tripod. Shinabery travels to Big Bat Cave once every 2 months to scan a new section of the cave. Credit: David Black

    A compass, some measuring tape, a couple of waterproof notebooks, and a pencil or indelible pen: These are the bare minimum supplies a caver needs to create a map of a cave. While one person measures, sets compass headings, and calculates angles and true distances, another person slowly trails behind, making intricate hand-drawn sketches of the cave’s geological features.

    These days, cavers also employ handheld instruments that use laser beams to determine heights and distances. This is how Dave Field, a retired geophysicist and avid caver who heads the Mid-Atlantic Karst Conservancy, maps caves in Pennsylvania. However, these small instruments don’t have the range needed to determine the size of large caverns where roofs and tunnel endings may be lost in darkness.

    Several hundred miles away, in Breckenridge County, Ky., cave enthusiast and former state cartographer Ken Bailey, who is now the president of the Kentucky Karst Conservancy, deploys a much more powerful laser technology to map caves. The equipment, called a lidar terrestrial scanner, offers much greater range and data-gathering ability than hand-held devices.

    Bailey has teamed up with Ben Shinabery, a land surveyor with access to a scanner, to create three-dimensional (3-D) cave maps of Big Bat Cave—the world’s 57th longest cave—near Custer, Ky. Unlike Field’s laser range finder, a lidar scanner pulses thousands of times per second, gathering thousands of data points per pulse. The data, when processed with powerful software, spit out a precise 3-D map of the cave, opening up whole worlds of information.

    First Maps, Then Science

    Although people have explored caves since there have been people, the quest for scientific insights from caves remains a challenge. Scientists who work in caves say that ways to map caves more thoroughly and accurately could have a major influence on how that quest goes.

    “I tell many cavers that [they’re] the Lewis and Clarks” of cave science, said George Veni, a hydrogeologist and executive director of the National Cave and Karst Research Institute. “Without these maps, we can’t do the science in any effective manner.”

    As a hydrogeologist, Veni looks at maps of caves that act as aquifers and can see how such caves function, right down to the permeability of the rocks, the structure, and the very plumbing of the terrain.

    Mapping caves with the precision of lidar could also open up investigations to a wide range of scientists outside of hydrology, Veni said, from biologists studying bat populations, to archeologists studying ancient societies, to geomorphologists studying how caves form, change, and erode. Caves also offer a multitude of localized paleoclimate data, Veni said, which could be revealed by 3-D maps.

    Lidar’s Ups and Downs

    Lidar has already proven itself a boon to science beyond the confines of caves. In the last couple of decades, scientists have used it to study Earth’s surface and atmosphere and to investigate forests, ice sheets, mountains, and even coral reefs in high resolution.

    Lidar works by shooting pulses of laser beams at a target, measuring how long it takes for the light to bounce back, and then calculating the distances. Some say that the technology’s name derives from “light radar” because the technology works like radar but uses pulses of light instead of radio waves. Others identify LIDAR as an acronym, probably for “light detection and ranging.”

    In Pennsylvania, Dave Field relies on publicly available aerial lidar data of the state’s topography to find sinkholes that might lead him to caves. Since the data became available, he said, the rate of discovering sinkholes has gone up significantly.

    “It’s been a real enlightenment just to see how much karst is out there,” Field said, using a term for any landscape built on rocks, such as limestone, that water slowly dissolves—a process that creates such features as sinkholes and caves.

    Below ground is another matter. The equipment isn’t terribly portable, Veni said. Cave exploration often requires a person to squeeze through excruciatingly tight tunnels, navigate up and down sudden rises or drops, and sometimes even swim through water—with only 3 centimeters of breathing room underneath a tunnel’s roof.

    “It’s a new tool, and, again, we’re taking it into an environment that is hostile to electronics,” Veni said.

    Because the technology is so expensive—a good lidar scanner can cost over a hundred thousand dollars—not many scientists have been able to take advantage of this valuable tool, Field noted.

    The Largest Caves

    Andy Eavis, a self-described “cave fanatic” who has been exploring caves for more than 50 years and has mapped more than 500 kilometers of caves around the world, is currently using lidar technology to scan the world’s largest cave chambers. In preparation for the International Union of Speleology meeting in 2017, he and his team plan to produce 3-D-printed models of the vast caverns. The purpose, Eavis said, is to concretely define particular cave terminology like “passageway” or “chamber” because there is still some disagreement over what exactly these terms mean. For instance, how wide is a “passageway”? How high must the roof be to call an area a “chamber”?

    Eavis and his team use a lidar scanner with a resolution of 1 centimeter and a range of up to 400 meters, which has suited their needs perfectly because one of the caves they scanned just last month—Cloud Ladder Hall in China—hosts a roof towering 365 meters (1197 feet).

    “These roofs are bigger than any roofs man has ever made. Structurally, they shouldn’t really stay up, they should have fallen down a long time ago,” Eavis said.

    In the past 2 years, Eavis and his team have mapped nine chambers in Malaysia, China, Spain, and France. Upcoming trips include visits to caves in Iran, Oman, Mexico, and Belize. A 3-D map produced by laser scanning of the Miao Room in China was recently documented in a National Geographic feature.

    After Eavis and his team are finished with their multicave scanning project, he says they’ll sell the $150,000 scanner because they will have no more use for it.

    Conservation Efforts

    Shinabery, the land surveyor, travels from Louisville, Ky., to Big Bat cave once every 2 months to scan another leg and is often accompanied by a team of volunteers—students looking for research experience, members of the community who want to explore the cave, or local scientists. The karst conservancy has already put together videos of the scanned portions of the cave. The green spheres that come and go in the video below are reference points set up by Shinabery. Likewise, the black boxes represent where the scanner was placed during each scan.

    download mp4 video here .

    Bailey hopes that creating 3-D maps of Big Bat Cave and other Kentucky caves might lead to more conservation efforts. Caves not only provide homes to living things, including bat colonies that are currently being decimated by white-nose syndrome, but also provide water to millions of people across the nation.

    However, if people can’t see the caves, they might not care, Bailey said.

    “We are protecting ourselves when we protect [caves],” he continued. “To be able to show people who will never go there why it’s worth saving is what the lidar is for me.”

    —JoAnna Wendel, Staff Writer

    Citation: Wendel, J. (2015), Laser beams brighten prospects for cave science, Eos, 96, doi:10.1029/2015EO040995. Published on 7 December 2015.

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    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

  • richardmitnick 9:42 pm on October 14, 2015 Permalink | Reply
    Tags: , , , Laser Technology   

    From ESA: “AIMing a light across millions of kilometres” 

    European Space Agency

    13 October 2015

    Laser communication with Earth

    Imagine beaming a light across millions of kilometres of empty space, all the way back to Earth. ESA’s proposed Asteroid Impact Mission [AIM] is intended to do just that: demonstrate laser communications across an unprecedented void.

    ESA AIM Asteroid Impact Mission

    The Asteroid Impact Mission, or AIM, undergoing detailed design ahead of a final go/no-go decision by ESA’s Ministerial Council in December 2016, is a deep-space technology-demonstration mission that would also be humanity’s first probe to a double asteroid.

    Among its innovative technologies, laser communications would return results to scientists several times faster than standard radio signals.

    “Optical communications in general is not yet a well-established technology for space and ESA’s European Data Relay System (EDRS) will be the first commercial application,” explains ESA optics engineer Zoran Sodnik.

    ESA’s laser station

    “In principle it works something like Morse code, with encoded rapid flashes on and off. ERDS with satellites in high orbits will use laser links to return environmental data from Europe’s low-orbiting Sentinel satellites on a realtime basis, a technique previously demonstrated using ESA’s Alphasat and Artemis telecom missions.

    “In 2013 ESA’s Optical Ground Station in Tenerife participated in a two-way contact with NASA’s LADEE lunar orbiter, across 400 000 km.

    “But AIM will need to operate much further: we are benchmarking a maximum span of 75 million kilometres, or half the distance between Earth and the Sun. That might sound like a lot, but operating around Mars one day will involve much further distances still.”

    Transmitter telescope

    A laser beam shone back from AIM’s 13.5 cm-diameter laser telescope at such a distance would have a ground footprint of about 1100 km – further than from London to Berlin. Also a lot but the equivalent radio beam radiating out across space would end up wider than our whole planet.

    “The much higher frequency of laser light is what gives us higher directivity and as a result increased bandwidth,” adds ESA laser engineer Clemens Heese.

    “At the same time, many photons will get lost on the way, so we need to use sophisticated photon counting methods to detect the signal reliably using our receiver telescope of around 1 m diameter.

    AIM laser

    While radio communications is a very mature technology and close to optimum efficiency, there’s still lots of room for development with optical communications. So this is the way we need to go to really boost the quantity and speed of data we can deliver to scientists.”

    To meet the challenge, ESA’s AIM team this month issued technology pre-development contracts to industry to tackle key issues including telescope design, detector electronics and coarse and fine-pointing systems. To give an idea of the kind of pointing required, AIM will need to align with the signal from Earth to within the diameter of planet Mars seen in our terrestrial sky.

    Laser for altimetry

    “At 39.3 kg, AIM’s laser system will be one of the single largest payload items,” explains Andres Galvez, heading ESA’s Science Analysis and System Support Unit.

    “We intend to gain maximum utility from it, by also using it for scientific purposes: the laser can also serve as an altimeter to chart the asteroid.”

    The system design is led by RUAG Space in Switzerland, building on its existing family of Optel laser communication terminals, the latest of which is tailored for direct-to-Earth downlinks from minisatellites.

    See the full article here .

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 2:53 pm on October 9, 2015 Permalink | Reply
    Tags: , , Laser Technology   

    From EPFL: “Using optical fibre to generate a two-micron laser” 

    EPFL bloc

    Ecole Polytechnique Federale Lausanne

    Emmanuel Barraud

    Camille Brès and Svyatoslav Kharitonov of EPFL

    Lasers with a wavelength of two microns could move the boundaries of surgery and molecule detection. Researchers at EPFL have managed to generate such lasers using a simple and inexpensive method.

    In recent years, two-micron lasers (0.002 millimetre) have been of growing interest among researchers. In the areas of surgery and molecule detection, for example, they offer significant advantages compared to traditional, shorter-wavelength lasers.
    However, two-micron lasers are still in their infancy and not yet as mature as their telecom counterparts (1.55-micron). Moreover sources currently used in labs are typically bulky and expensive. Optical fibre-based 2 micron lasers are an elegant solution to these issues. This is where researchers at Photonics Systems Laboratory (PHOSL) come in.

    In an article published in Light: Science & Applications, the team of Camille Brès at EPFL described a way to design these lasers at a lower cost, by changing the way optical fibres are connected to each other. Thanks to the new configuration, they were able not only to produce very good 2 micron lasers, but also to do without an expensive and complex component that is normally required.

    Bloodless surgery and long-range molecule détection

    Two-micron spectral domain has potential applications in medicine, environmental sciences and industry. At these wavelengths, the laser light is easily absorbed by water molecules, which are the main constituents of human tissue. In the realm of high precision surgery, they can be used to target water molecules during an operation and make incisions in very small areas of tissue without penetrating deeply. What is more, the energy from the laser causes the blood to coagulate on the wound, which prevents bleeding.

    Two-micron lasers are also very useful for detecting key meteorological data over long distances through the air. Not to mention that they are highly effective in the processing of various industrial materials.

    Replacing a cop with a detour

    To create a 2 micron fibre-laser, light is usually injected into an optical-fibre ring containing a gain region which amplifies 2 micron light. The light circulates in the ring, passing through the gain region many times thus gaining more and more power, until becoming a laser. For optimal operation, these systems include a costly component called isolator, which forces the light to circulate in a single direction.

    At PHOSL, researchers built a thulium-doped fibre laser that works without an isolator. Their idea was to connect the fibres differently, to steer light instead of stopping it. “We plug a kind of deviation that redirects the light heading in the wrong direction, putting it back on track”, said Camille Brès. This means no more need for the isolator, whose job is to stop light moving in the wrong direction, sort of like a traffic cop. “We replaced the traffic cop with a detour,” said Svyatoslav Kharitonov, the article’s lead author.

    Higher quality laser

    The new system not only proved to be less expensive than more traditional ones, it also showed it could generate a higher quality laser light. The explanation is as follows: the laser output gets purified because light interacts with itself in a very special way, thanks to the amplifying fibre’s composition and dimensions, and the high power circulating in this atypical laser architecture.
    “While the association of amplifying fibres and high power usually weakens traditional lasers performance, it actually improves the quality of this laser, thanks to our specific architecture”, said Svyatoslav Kharitonov.

    See the full article here .

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    EPFL is Europe’s most cosmopolitan technical university. It receives students, professors and staff from over 120 nationalities. With both a Swiss and international calling, it is therefore guided by a constant wish to open up; its missions of teaching, research and partnership impact various circles: universities and engineering schools, developing and emerging countries, secondary schools and gymnasiums, industry and economy, political circles and the general public.

  • richardmitnick 7:25 pm on August 18, 2015 Permalink | Reply
    Tags: , Laser Technology, ,   

    From LLNL: “National Ignition Facility fires 300th shot in FY15” 

    Lawrence Livermore National Laboratory

    NIF Bloc

    Aug. 18, 2015
    Breanna Bishop

    NIF’s target chamber is where the magic happens – temperatures of 100 million degrees and pressures extreme enough to compress the target to densities up to 100 times the density of lead are created there. Photo by Damien Jemison/LLNL

    Last week, the National Ignition Facility (NIF) fired its 300th laser target shot in fiscal year (FY) 2015, meeting the year’s goal more than six weeks early. In comparison, the facility completed 191 target shots in FY 2014. Located at Lawrence Livermore National Laboratory (LLNL), the NIF is the world’s most energetic laser.

    Increasing the shot rate has been a top priority for the Inertial Confinement Fusion (ICF) Program and in particular the NIF team at LLNL. The greater than 50 percent increase in NIF shots from FY 2014 to FY 2015 is a direct result of the implementation of an efficiency study conducted in FY 2014 for the NIF.

    NIF is funded by the National Nuclear Security Administration (NNSA), the agency charged with ensuring the nation’s nuclear security. The chief mission of NIF is to provide experimental insight and data for NNSA’s science-based Stockpile Stewardship Program in the area of high-energy-density physics, a scientific field of direct relevance to nuclear deterrence and national nuclear security.

    “Demand for experiments at NIF have always exceeded capacity. The impressive work by the team at NIF to produce additional shots has provided important new opportunities for NIF users and increased this unique scientific platform’s contributions to national security,” said Brig. Gen Stephen Davis, USAF, acting deputy administrator for Defense Programs. “I congratulate the NIF team and its many partners for not only meeting, but exceeding the goal.”

    The NIF Control Room preparing for the 300th shot. From left: Shot Director Dean Latray, Operations Manager Bruno Van Wonterghem and Lead Operator Rod Rinnert. Photo by Jason Laurea/LLNL.

    “Achieving 300 shots this year enabled so many critical accomplishments: first-of-a-kind dynamic materials data, more efficiently driven ICF capsules, increased opportunities for academic users, new radiation sources for the Department of Defense and acceleration of new diagnostic development,” said Keith LeChien, director of ICF for NNSA.

    “This is a remarkable achievement for team NIF, whose incredible effort and persistence turned this huge challenge into a reality,” said LLNL Director Bill Goldstein. “Without the support of NNSA and our many partners, this would not have been possible.”

    This 120-day efficiency study was developed in partnership with other NNSA laboratories and drew on best practices at the Z Facility at Sandia National Laboratories and the Omega Laser at the University of Rochester. This study identified more than 80 improvements to equipment and procedures that could lead to reduced time and effort for fielding experiments.

    To date, the NIF team has implemented more than 50 of these improvements and will continue implementing the remainder of the improvements in FY 2016. Improvements include equipment modifications to reduce the time needed to perform critical tasks. Some of the most significant were control system improvements to streamline the shot cycle; process improvements to reduce time needed to align targets and diagnostics; and user interface improvements to make it easier for users to set up and execute experiments.

    See the full article here.

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  • richardmitnick 1:57 pm on August 14, 2015 Permalink | Reply
    Tags: Laser Technology,   

    From MPG: “A novel source of X-rays for imaging purposes” 

    Max Planck Institute of Quantum Optics bloc

    Max Planck Institute of Quantum Optice

    June 16, 2015
    Thorsten Naeser

    Physicists at LMU Munich and the Max Planck Institute of Quantum Optics have validated a novel laser-driven means of generating bright and highly energetic X-ray beams. The method opens up new ways of imaging the fine structure of matter.

    For over a century, medical imaging has made use of X-rays produced in a specialized type of vacuum tube. The major disadvantage of this method lies in the poor quality of the emitted radiation. The source emits radiation from a large spot into all directions and over a broad energy range. These features are responsible for the relatively modest resolution attainable with this mode of imaging. X-rays generated in synchrotrons provide much higher resolution, but their dimensions and cost preclude their routine use in clinical settings. However, an alternative approach is now available, for two laser pulses can generate X-rays of similar quality to synchrotron radiation in devices with a far smaller footprint: One pulse accelerates electrons to very high energy and the other forces them into an undulating motion. Under these conditions, electrons emit X-radiation that is both highly energetic (‚hard‘) and highly intense, and is therefore ideal for probing the microscopic structure of matter. Now, physicists based at the Laboratory for Attosecond Physics (LAP) at LMU Munich and the Max Planck Institute of Quantum Optics (MPQ) have developed such a laser-driven X-ray source for the first time. With the aid of two laser pulses, the researchers have generated ultrashort bursts of X-rays with defined wavelengths tailored for different applications. The new source can image structures of varying composition with a resolution of less than 10 micrometers. This breakthrough opens up a range of promising perspectives in materials science, biology and – in particular – medicine.

    The ATLAS Lasersystem based in the Laboratory for Extreme Photonics of the Ludwig-Maximilians University Munich, serves as a light source for the new brilliant X-ray radiation. (Photo: Thorsten Naeser)

    Imaging of microscopic structures in any sample of matter requires the use of a very brilliant beam of light with a very short wavelength. Brilliant radiation is able to concentrate a maximum amount of light quanta or photons of a single defined wavelength within the smallest area and shortest duration. Hard X-radiation is therefore ideal for this purpose, because it penetrates matter and exhibits wavelengths of a few hundredths of a nanometer (few-hundredths of a billionth of a meter, 10-11 m). Unfortunately, the only sources of high-intensity beams of hard X-rays so far available are particle accelerators, which are typically huge and highly expensive. But there is, in principle, a far more economical and compact way of doing the job – with optical light.

    A team at the Laboratory for Attosecond Physics, which is run jointly by LMU and the MPQ, has now taken an important step towards realizing this goal. Led by Prof. Stefan Karsch and Dr. Laszlo Veisz, the scientists have succeeded in generating bright beams of hard X-radiation by purely optical means. Moreover, the wavelength of the emitted radiation can be readily adjusted to cater for different applications.

    The physicists focused a laser pulse, lasting 25 femtoseconds and packing 60 terawatts (6×10^13 Watts) of power, onto a fine jet of hydrogen gas. Note here that the output of a nuclear power station – 1500 MW (1.5×109 Watts) – is very modest by comparison, but each pulse only lasts for 25 millionths of a billionth of a second. The strong electric field associated with each pulse knocks negatively charged electrons out of the gas, giving rise to a cloud of ionized particles, or ‘plasma’. The wavefront courses through the plasma like a snow-plow, sweeping the electrons aside and leaving behind the positively charged atoms (which are much heavier). The separation of oppositely charged particles generates very strong electrical fields, which cause the displaced electrons to whiplash back and forth. This in turn creates a wave-like pattern within the plasma, which propagates in the wake of the laser pulse, rather like the trailing wave caused by the keel of a speedboat racing on a lake. A fraction of the free electrons are caught up in this wave and can effectively ride on it like a surfer, directly behind the advancing laser pulse. Indeed, in this ‘wakefield’, the surfing electrons can be rapidly accelerated to velocities very near the speed of light.

    When the electrons have reached their maximal speed they are allowed to collide head-on with a counter-propagating laser pulse, creating a so-called optical undulator whose oscillating electric field causes the free electrons to oscillate along a direction perpendicular to their direction of propagation. Highly energetic electrons that are forced to oscillate in this way emit radiation in the form of X-ray photons with wavelengths as short as 0.03 nm. In addition, in these experiments, the higher harmonics (waves whose frequency is an integer multiple of the fundamental frequency) entrained on the electron motions by the light field could be detected directly in the X-ray spectrum – a feat that has been attempted many times on conventional particle accelerators without success.

    One of the great advantages of the new system in comparison with conventional X-ray sources is that the wavelength of the emitted light can be tuned over a wide range. This ability to alter the wavelength allows radiologists to analyze different types of tissue, for instance. By fine-tuning the incident beam, one can gain the maximum information about the sample one wishes to characterize.

    Not only is the laser-driven radiation tunable and extremely bright, it is produced in pulsed form. Each 25-fs laser pulse gives rise to X-ray flashes of a few fs duration. This makes it useful for applications such as time-resolved spectroscopy, which is used to investigate ultrafast processes at the level of atoms and electrons. The intensity of the pulses (i.e. the number of photons per pulse) generated by the new source is not yet high enough for this task, but the researchers hope to overcome this obstacle with the aid of the facilities at the new Centre for Advanced Laser Applications (CALA), now being built on the Garching Campus.

    The new optically generated radiation can also be combined with phase-contrast X-ray tomography, an imaging procedure that is being refined by Prof. Franz Pfeiffer of the Technical University of Munich (TUM). This technique extracts information from the light that is scattered (rather than that absorbed) by an object. “Using this method, we can already image structures as small as 10 micrometers in diameter in opaque materials,” Stefan Karsch explains. “With our new X-ray source, we will be able to obtain even more detailed information from living tissues and other materials,” he adds.

    See the full article here.

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    Max Planck Institute of Quantum Optics campus

    Research at the Max Planck Institute of Quantum Optics
    Light can behave as an electromagnetic wave or a shower of particles that have no mass, called photons, depending on the conditions under which it is studied or used. Matter, on the other hand, is composed of particles, but it can actually exhibit wave-like properties, giving rise to many astonishing phenomena in the microcosm.

    At our institute we explore the interaction of light and quantum systems, exploiting the two extreme regimes of the wave-particle duality of light and matter. On the one hand we handle light at the single photon level where wave-interference phenomena differ from those of intense light beams. On the other hand, when cooling ensembles of massive particles down to extremely low temperatures we suddenly observe phenomena that go back to their wave-like nature. Furthermore, when dealing with ultrashort and highly intense light pulses comprising trillions of photons we can completely neglect the particle properties of light. We take advantage of the large force that the rapidly oscillating electromagnetic field exerts on electrons to steer their motion within molecules or accelerate them to relativistic energies.

  • richardmitnick 9:30 am on August 11, 2015 Permalink | Reply
    Tags: , Laser Technology, ,   

    From LLNL: “Researchers reveal new electron ring formations” 

    Lawrence Livermore National Laboratory

    Aug. 11, 2015
    Breanna Bishop
    bishop33@llnl.gov (link sends e-mail)

    Using the ultra-short-pulse Callisto laser system at LLNL’s Jupiter Laser Facility, a team of scientists from LLNL and UCLA revealed new, never-before-seen electron ring formations. Photo by Julie Russell/LLNL

    This image from the 3D simulation shows the laser pulse propagating to the right through the low-density plasma. The black region behind the laser contains background ions, which are responsible for accelerating electrons in this region to high energy. The white contours represent regions of high background electron density; the roughly triangular region they form between the two black regions is called the “pocket,” and it is able to guide electrons through the plasma and allow them to leave it with a ring-like structure.

    Laser wakefield acceleration, a process where electron acceleration is driven by high-powered lasers, is well-known for being able to produce high-energy beams of electrons in tabletop-scale distances. However, in recent experiments, a team of scientists from Lawrence Livermore National Laboratory (LLNL) and the University of California, Los Angeles (UCLA) revealed new, never-before-seen electron ring formations in addition to the typically observed beams.

    In a recently published Physical Review Letters , the team described electron acceleration experiments performed at LLNL’s Jupiter Laser Facility. Using the ultra-short-pulse Callisto laser system, a plasma was produced in a low-density gas cell target. The interaction of the high-intensity laser with the gas created a relativistic plasma wave, which then accelerated some of the electrons in the plasma to more than 100 megaelectron volt (MeV) energies.

    These electron beams are usually directed along the laser axis and have fairly low divergence. In these experiments, the typical beams were observed, but in certain cases were also accompanied by a second, off-axis beam that had a ring-like shape. This new feature had never before been reported, and its origin was unclear until the UCLA collaborators finished computationally intensive three-dimensional calculations of the experimental conditions.

    “The dynamics of the plasma wave are often calculated in simulations, but the small spatial scale and fast timescale of the wakefield process has made direct measurements of many effects difficult or impractical,” said lead author Brad Pollock. “The discovery of new features, such as the electron rings here, allows us to compare with simulations and infer what is going on in the experiments with much greater confidence.”

    In the simulations, a ring-like electron structure was produced during the wakefield acceleration process if the plasma was sufficiently long and the total number of electrons was large enough to perturb the plasma wave structure. Under these conditions, the plasma wave structure was modified in such a way as to force some electrons off of the laser axis and into a “pocket” outside of the plasma wave, which then guided some of these electrons through the remainder of the plasma.

    “In addition to the diagnostic implications of this particular feature, it may also be possible to tailor the parameters of electron ring-beams for their own applications, including accelerating positively charged particles – positrons, for example,” Pollock added.

    LLNL co-authors include Felicie Albert, Arthur Pak and Joseph Ralph, and UCLA co-authors include Frank Tsung, Jessica Shaw, Chris Clayton, Asher Davidson, Nuno Lemos, Ken Marsh, Warren Mori and Chan Joshi.

    See the full article here.

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  • richardmitnick 9:32 am on August 3, 2015 Permalink | Reply
    Tags: , , Laser Technology   

    From ASU: “ASU researchers demonstrate the world’s first white lasers” 

    ASU Bloc


    July 28, 2015

    Sharon Keeler, sharon.keeler@asu.edu
    Ira A. Fulton Schools of Engineering

    This schematic illustrates the novel nanosheet with three parallel segments created by the researchers, each supporting laser action in one of three elementary colors. The device is capable of lasing in any visible color, completely tunable from red, green to blue, or any color in between. When the total field is collected, a white color emerges.
    Photo by: ASU/Nature Nanotechnology

    More luminous and energy efficient than LEDs, white lasers look to be the future in lighting and light-based wireless communication

    While lasers were invented in 1960 and are commonly used in many applications, one characteristic of the technology has proven unattainable. No one has been able to create a laser that beams white light.

    Researchers at Arizona State University have solved the puzzle. They have proven that semiconductor lasers are capable of emitting over the full visible color spectrum, which is necessary to produce a white laser.

    The researchers have created a novel nanosheet – a thin layer of semiconductor that measures roughly one-fifth of the thickness of human hair in size with a thickness that is roughly one-thousandth of the thickness of human hair – with three parallel segments, each supporting laser action in one of three elementary colors. The device is capable of lasing in any visible color, completely tunable from red, green to blue, or any color in between. When the total field is collected, a white color emerges.

    The researchers, engineers in ASU’s Ira A. Fulton Schools of Engineering, published their findings in the July 27 advance online publication of the journal Nature Nanotechnology. Cun-Zheng Ning, professor in the School of Electrical, Computer and Energy Engineering, authored the paper, A monolithic white laser, with his doctoral students Fan Fan, Sunay Turkdogan, Zhicheng Liu and David Shelhammer. Turkdogan and Liu completed their doctorates after this research.

    The technological advance puts lasers one step closer to being a mainstream light source and potential replacement or alternative to light emitting diodes (LEDs). Lasers are brighter, more energy efficient, and can potentially provide more accurate and vivid colors for displays like computer screens and televisions. Ning’s group has already shown that their structures could cover as much as 70 percent more colors than the current display industry standard.

    Another important application could be in the future of visible light communication in which the same room lighting systems could be used for both illumination and communication. The technology under development is called Li-Fi for light-based wireless communication, as opposed to the more prevailing Wi-Fi using radio waves. Li-Fi could be more than 10 times faster than current Wi-Fi, and white laser Li-Fi could be 10 to 100 times faster than LED based Li-Fi currently still under development.

    “The concept of white lasers first seems counterintuitive because the light from a typical laser contains exactly one color, a specific wavelength of the electromagnetic spectrum, rather than a broad-range of different wavelengths. White light is typically viewed as a complete mixture of all of the wavelengths of the visible spectrum,” said Ning, who also spent extended time at Tsinghua University in China during several years of the research.

    In typical LED-based lighting, a blue LED is coated with phosphor materials to convert a portion of the blue light to green, yellow and red light. This mixture of colored light will be perceived by humans as white light and can therefore be used for general illumination.

    Sandia National Labs in 2011 produced high-quality white light from four separate large lasers. The researchers showed that the human eye is as comfortable with white light generated by diode lasers as with that produced by LEDs, inspiring others to advance the technology.

    “While this pioneering proof-of-concept demonstration is impressive, those independent lasers cannot be used for room lighting or in displays,” Ning said. “A single tiny piece of semiconductor material emitting laser light in all colors or in white is desired.”

    Semiconductors, usually a solid chemical element or compound arranged into crystals, are widely used for computer chips or for light generation in telecommunication systems. They have interesting optical properties and are used to make lasers and LEDs because they can emit light of a specific color when a voltage is applied to them. The most preferred light emitting material for semiconductors is indium gallium nitride, though other materials such as cadmium sulfide and cadmium selenide also are used for emitting visible colors.

    The main challenge, the researchers noted, lies in the way light emitting semiconductor materials are grown and how they work to emit light of different colors. Typically a given semiconductor emits light of a single color – blue, green or red – that is determined by a unique atomic structure and energy bandgap.

    The “lattice constant” represents the distance between the atoms. To produce all possible wavelengths in the visible spectral range you need several semiconductors of very different lattice constants and energy bandgaps.

    “Our goal is to achieve a single semiconductor piece capable of laser operation in the three fundamental lasing colors. The piece should be small enough, so that people can perceive only one overall mixed color, instead of three individual colors,” said Fan. “But it was not easy.”

    “The key obstacle is an issue called lattice mismatch, or the lattice constant being too different for the various materials required,” Liu said. “We have not been able to grow different semiconductor crystals together in high enough quality, using traditional techniques, if their lattice constants are too different.”

    The most desired solution, according to Ning, would be to have a single semiconductor structure that emits all needed colors. He and his graduate students turned to nanotechnology to achieve their milestone.

    The key is that at nanometer scale larger mismatches can be better tolerated than in traditional growth techniques for bulk materials. High quality crystals can be grown even with large mismatch of different lattice constants.

    Recognizing this unique possibility early on, Ning’s group started pursuing the distinctive properties of nanomaterials, such as nanowires or nanosheets, more than 10 years ago. He and his students have been researching various nanomaterials to see how far they could push the limit of advantages of nanomaterials to explore the high crystal quality growth of very dissimilar materials.

    Six years ago, under U.S. Army Research Office funding, they demonstrated that one could indeed grow nanowire materials in a wide range of energy bandgaps so that color tunable lasing from red to green can be achieved on a single substrate of about one centimeter long. Later on they realized simultaneous laser operation in green and red from a single semiconductor nanosheet or nanowires. These achievements triggered Ning’s thought to push the envelope further to see if a single white laser is ever possible.

    Blue, necessary to produce white, proved to be a greater challenge with its wide energy bandgap and very different material properties.

    “We have struggled for almost two years to grow blue emitting materials in nanosheet form, which is required to demonstrate eventual white lasers, ” said Turkdogan, who is now assistant professor at University of Yalova in Turkey.

    After exhaustive research, the group finally came up with a strategy to create the required shape first, and then convert the materials into the right alloy contents to emit the blue color. Turkdogan said, “To the best of our knowledge, our unique growth strategy is the first demonstration of an interesting growth process called dual ion exchange process that enabled the needed structure.”

    This strategy of decoupling structural shapes and composition represents a major change of strategy and an important breakthrough that finally made it possible to grow a single piece of structure containing three segments of different semiconductors emitting all needed colors and the white lasers possible. Turkdogan said that, “this is not the case, typically, in the material growth where shapes and compositions are achieved simultaneously.”

    While this first proof of concept is important, significant obstacles remain to make such white lasers applicable for real-life lighting or display applications. One of crucial next steps is to achieve the similar white lasers under the drive of a battery. For the present demonstration, the researchers had to use a laser light to pump electrons to emit light. This experimental effort demonstrates the key first material requirement and will lay the groundwork for the eventual white lasers under electrical operation.

    See the full article here.

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    ASU is the largest public university by enrollment in the United States.[11] Founded in 1885 as the Territorial Normal School at Tempe, the school underwent a series of changes in name and curriculum. In 1945 it was placed under control of the Arizona Board of Regents and was renamed Arizona State College.[12][13][14] A 1958 statewide ballot measure gave the university its present name.
    ASU is classified as a research university with very high research activity (RU/VH) by the Carnegie Classification of Institutions of Higher Education, one of 78 U.S. public universities with that designation. Since 2005 ASU has been ranked among the Top 50 research universities, public and private, in the U.S. based on research output, innovation, development, research expenditures, number of awarded patents and awarded research grant proposals. The Center for Measuring University Performance currently ranks ASU 31st among top U.S. public research universities.[15]

    ASU awards bachelor’s, master’s and doctoral degrees in 16 colleges and schools on five locations: the original Tempe campus, the West campus in northwest Phoenix, the Polytechnic campus in eastern Mesa, the Downtown Phoenix campus and the Colleges at Lake Havasu City. ASU’s “Online campus” offers 41 undergraduate degrees, 37 graduate degrees and 14 graduate or undergraduate certificates, earning ASU a Top 10 rating for Best Online Programs.[16] ASU also offers international academic program partnerships in Mexico, Europe and China. ASU is accredited as a single institution by The Higher Learning Commission.

    ASU Tempe Campus
    ASU Tempe Campus

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

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