Tag Archives: laser

Chinese ‘Death Star’ For Submarines

China is developing a satellite with a powerful laser for anti-submarine warfare that researchers hope will be able to pinpoint a target as far as 500 metres below the surface. It is the latest addition to the country’s expanding deep-sea surveillance programme, and aside from targeting submarines – most operate at a depth of less than 500 metres – it could also be used to collect data on the world’s oceansProject Guanlan, meaning “watching the big waves”, was officially launched in May at the Pilot National Laboratory for Marine Science and Technology in Qingdao, Shandong. It aims to strengthen China’s surveillance activities in the world’s oceans, according to the laboratory’s website.

Scientists are working on the satellite’s design at the laboratory, but its key components are being developed by more than 20 research institutes and universities across the country. Song Xiaoquan, a researcher involved in the project, said if the team can develop the satellite as planned, it will make the upper layer of the seamore or less transparent”. “It will change almost everything,” Song said.

While light dims 1,000 times faster in water than in the air, and the sun can penetrate no more than 200 metres below the ocean surface, a powerful artificial laser beam can be 1 billion times brighter than the sun. But this project is ambitious – naval researchers have tried for more than half a century to develop a laser spotlight for hunting submarines using technology known as light detection and ranging (lidar). In theory, it works like this – when a laser beam hits a submarine, some pulses bounce back. They are then picked up by sensors and analysed by computer to determine the target’s location, speed and three-dimensional shape.

But in real life, lidar technology can be affected by the device’s power limitations, as well as cloud, fog, murky water – and even marine life such as fish and whales. Added to that, the laser beam deflects and scatters as it travels from one body of water to another, making it more of a challenge to get a precise calculation. Experiments carried out by the United States and former Soviet Union achieved maximum detection depths of less than 100 metres, according to openly available information. That range has been extended in recent years by the US in research funded by Nasa and the Defence Advanced Research Projects Agency (DARPA).

Source: https://www.scmp.com/

How To Manipulate And Move Cells With Light

Wits physicists demonstrate a new device for manipulating and moving tiny objects with light. When you shine a beam of light on your hand, you don’t feel much, except for a little bit of heat generated by the beam. When you shine that same light into a world that is measured on the nano– or micro scale, the light becomes a powerful manipulating tool that you can use to move objects around – trapped securely in the light.

Researchers from the Structured Light group from the School of Physics at the University of the Witwatersrand in Johannesburg, South Africa, have found a way to use the full beam of a laser light, to control and manipulate minute objects such as single cells in a human body, tiny particles in small volume chemistry, or working on future on-chip devices. While the specific technique, called holographic optical trapping and tweezing, is not new, the Wits Researchers found a way to optimally use the full force of the light – including vector light that was previously unavailable for this application. This forms the first vector holographic trap.

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Previously holographic traps were limited to particular classes of light (scalar light), so it is very exciting that we can reveal a holistic device that covers all classes of light, including replicating all previous trapping devices,” explains Professor Andrew Forbes, team leader of the collaboration and Distinguished Professor in the School of Physics where he heads up the Wits Structured Light Laboratory.

What we have done is that we have demonstrated the first vector holographic optical trapping and tweezing system. The device allows micrometer sized particles, such as biological cells, to be captured and manipulated only with light.”

Source: https://www.wits.ac.za/

A Wearable Device For Regrowing Hair

Although some people embrace the saying “bald is beautiful,” for others, alopecia, or excessive hair loss, can cause stress and anxiety. Some studies have shown that stimulating the skin with lasers can help regrow hair, but the equipment is often large, consumes lots of energy and is difficult to use in daily life. Now, researchers have developed a flexible, wearable photostimulator that speeds up hair growth in mice. 

Affecting millions of men and women worldwide, alopecia has several known causes, including heredity, stress, aging and elevated male hormones. Common treatments include medications, such as minoxidil, corticosteroid injections and hair transplant surgery. In addition, irradiating the bald area with a red laser can stimulate hair follicles, causing cells to proliferate. However, this treatment is often impractical for home use. So, Keon Jae Lee and colleagues wanted to develop a flexible, durable photostimulator that could be worn on human skin.

Shaved mice with flexible vertical LEDs (f-VLEDs) regrows hair faster than no treatment (Con) or minoxidil injections (MNX)

The team fabricated an ultrathin array of flexible vertical micro-light-emitting diodes (mLEDs). The array consisted of 900 red mLEDs on a chip slightly smaller than a postage stamp and only 20 mm thick. The device used almost 1,000 times less power per unit area than a conventional phototherapeutic laser, and it did not heat up enough to cause thermal damage to human skin. The array was sturdy and flexible, enduring up to 10,000 cycles of bending and unbending. The researchers tested the device’s ability to regrow hair on mice with shaved backs. Compared with untreated mice or those receiving minoxidil injections, the mice treated with the mLED patch for 15 minutes a day for 20 days showed significantly faster hair growth, a wider regrowth area and longer hairs.

The findings are reported in ACS Nano.

Source: https://www.acs.org/

Climate Change: How To Forecast Changes In Weather More Accurately

Europe is launching  a satellite this week that will use new laser technology to measure the winds sweeping across Earth and help scientists forecast changes in weather more accurately.

The Aeolus mission will provide scientists with data on winds in remote areas, such as over oceans, that they have not been able to get from weather balloons, ground stations and airplanes but which are crucial to predicting changes in weather.

Forecasting is of course still limited, but then we will certainly be able to understand the processes better that lead to extreme weather phenomena,” Paolo Ferri, the European Space Agency’s (ESA) head of mission operations, told  ahead of the launch.

Many scientists warn that global warming will result in more frequent and intense heatwaves, precipitation and storms, causing billions of euros in damage and costing thousands of human lives every year.

Better weather forecasts will allow scientists to warn the population when hurricanes are heading their way and predict weather patterns such as El Niño, which can cause crop damage, fires and flash floods.

The Aeolus mission – named after a character of Greek mythology who was appointed keeper of the winds – is scheduled to blast off from Europe’s space port in Kourou, French Guiana

Source: https://www.reuters.com/

Colorful 3D Printing

People are exploring the use of 3D printing for wide-ranging applications, including manufacturing, medical devices, fashion and even food. But one of the most efficient forms of 3D printing suffers from a major drawback: It can only print objects that are gray or black in color. Now, researchers have tweaked the method so it can print in all of the colors of the rainbow.

THIS BRIGHTLY COLORED DRAGON WAS PRODUCED BY 3D PRINTING, USING GOLD NANORODS AS PHOTOSENSITIZERS.

Selective laser sintering (SLS) printers use a laser to heat specific regions of a powdered material, typically nylon or polyamide, so that the powder melts or sinters to form a solid mass. The printer adds then selectively sinters new powdered material layer by layer until the desired 3D structure is obtained. To reduce the energy requirements of the process, researchers have added compounds called photosensitizers to the polymer powders. These materials, such as carbon nanotubes, carbon black and graphene, absorb light much more strongly than the polymers and transfer heat to them, enabling the use of cheaper, lower-power lasers. However, the carbon-based photosensitizers can only produce printed objects that are gray or black. Gerasimos Konstantatos, Romain Quidant and their coworkers at The Institute of Photonic Sciences (IFCO) wanted to find a photosensitizer that would enable color printing by the SLS method.

The researchers designed gold nanorods to strongly absorb in the near-infrared region of the spectrum while being almost transparent to visible light. They coated them with silica and then mixed them with polyamide powders to print 3D objects. They found that the gold nanorods were much better at converting light from the laser to heat than carbon black, the industry standard. Also, the new photosensitizers could produce much whiter and — when mixed with dyes — brightly colored 3D objects. Importantly, the materials are cost-effective for large-scale production. The researchers have filed several patent applications related to the new technology.

The findings are reported in the ACS journal Nano Letters.

Source: https://www.acs.org/

A stamp-sized nanofilm stores more data than 200 DVDs

Ninety percent of the world’s data has been created in the last two years, with a massive 2.5 quintillion bytes generated every single day. As you might suspect, this causes some challenges when it comes to storage. While one option is to gradually turn every square inch of free land into giant data centers, researchers from the  Center for Advanced Optoelectronic Functional Material Research, Northeast Normal University (China) may have come up with a more elegant solution. In a potential breakthrough, they have developed a new nanofilm80 times thinner than a human hair — that is able to store large amounts of data holographically. A single 10-by-10 cm piece of this film could archive more than 1,000 times the amount of data found on a DVD. By our count, that means around 8.5 TB of data. This data can also be retrieved incredibly quickly, at speeds of up to 1GB per second: The equivalent of 20 times the reading speed of modern flash memory.

In the journal Optical Materials Express, the researchers detail the fabrication process of the new film. This involves using a laser to write information onto silver nanoparticles on a titanium dioxide (titania) semiconductor film. This stores the data in the form of 3D holograms, thereby allowing it to be compressed into smaller spaces than regular optical systems.

That’s exciting enough, but what really makes the work promising is the fact that the data is stored in a way that is stable. Previous attempts at creating films for holographic data storage have proven less resilient than alternate storage methods since they can be wiped by exposure to ultraviolet light. That makes them less-than-viable options for long-term information storage. The creators of this new film, however, have shown that it has a high stability even in the presence of such light. This environmental stability means that the device could be used outside — or even conceivably in harsher radiation conditions like outer space.

Going forward, the researchers aim to test their new film by putting it through its paces outdoors. Should all go according to plan, it won’t be too long before this is available on the market. We might be willing to throw down a few bucks on Kickstarter for a piece!

Source: https://www.osapublishing.org
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https://www.digitaltrends.com/

How Solar Cells Absorb 20 % More Sunlight

Trapping light with an optical version of a whispering gallery, researchers at the National Institute of Standards and Technology (NIST) have developed a nanoscale coating for solar cells that enables them to absorb about 20 percent more sunlight than uncoated devices. The coating, applied with a technique that could be incorporated into manufacturing, opens a new path for developing low-cost, high-efficiency solar cells with abundant, renewable and environmentally friendly materials.

Illustration shows the nanoresonator coating, consisting of thousands of tiny glass beads, deposited on solar cells. The coating enhances both the absorption of sunlight and the amount of current produced by the solar cells

The coating consists of thousands of tiny glass beads, only about one-hundredth the width of a human hair. When sunlight hits the coating, the light waves are steered around the nanoscale bead, similar to the way sound waves travel around a curved wall such as the dome in St. Paul’s Cathedral in London. At such curved structures, known as acoustic whispering galleries, a person standing near one part of the wall easily hears a faint sound originating at any other part of the wall.

Using a laser as a light source to excite individual nanoresonators in the coating, the team found that the coated solar cells absorbed, on average, 20 percent more visible light than bare cells. The measurements also revealed that the coated cells produced about 20 percent more current.

Source: https://www.nist.gov/