Archive for 12月, 2016

When the Tactical Laser Weapons on the Battlefield?

火曜日, 12月 13th, 2016

Although the laser from the date of birth, by the military’s widespread attention, especially in the field of strategic anti missile. But because of the difficulties of the atmosphere, the optical attenuation, the heat dissipation and the target guidance, the development speed of the strategic high power laser pointer weapon is very slow. But since twenty-first Century, the U.S. military once again starting to focus on the development of high power solid state laser, which is used to perform short-range air defense and Antimissile Defence, warship tactical mission, and the U.S. military said a mysterious weapon again ahead of competitors.

In high power solid state laser fiber tactical laser weapon, because of its obvious advantages in efficiency, laser beam quality, system size, weight, firmness and cooling etc., is becoming the main source of tactical laser weapon. Recently, the U.S. military developed a variety of laser weapons prototype, all fiber laser weapons. Such as the U.S. Defense Advanced Research Projects Agency (DARPA) regional defense against ammunition system of “rapier” project, the Navy tactical laser weapon system with laser weapon system project, the “army” (ADAM) and “Zeus Hummer laser ammunition to destroy the system” are used in fiber laser.

Among them, the “sword” is an airborne burning laser pointer weapons project, the goal is to reflect electricity or infrared-guided surface-to-air missiles, combat altitude of 15 km. The US Navy’s Mk38 shipborne laser cannon combat target is a large number of intensive small vessels, sea ships, air vehicles and so on. In 2011, the laser gun fired on air and surface targets. The US Army’s Regional Defense Anti-Ballistic System is primarily a threat to ground-based short-range air defense targets (rocket and unmanned aerial vehicles). In the 2012 and 2013 tests, the system successfully destroyed the UAV And small-caliber rockets. The “Zeus – Hummer laser ammunition destruction system” is installed in the famous “Hummer” car, with anti-mine and the ability to deal with roadside bombs.

In addition to the above, the US military there are some optical fiber tactical laser project. Now the US military tactical laser weapons for the development of very enthusiastic, in the “large area network” stage. The Pentagon in 2014 launched the third “offset strategy”, the core is the development of disruptive advanced technology weapons, continue to occupy an absolute advantage in the military competition. US Deputy Secretary of Defense Robert Walker believes that the third “offset strategy” is to establish the core of the advantages of precision-guided weapons in the successful escape of enemy precision-guided attacks while destroying each other. Many US military experts also believe that tactical 2000mw laser pointer weapons, is clearly the third “offset strategy” should focus on the development of the project.

China’s research and development of 20,000-watt (20KW) fiber laser, can be applied to China’s tactical laser weapons research and development? It is estimated that there is a distance. First of all, one of the key components of fiber laser weapons is single-mode fiber lasers. Its representative is the United States IPG photon 10KW single-mode fiber laser. In addition to being widely civilian, but also by the US military procurement of a large number of tactical laser weapons for the basic module. As mentioned above, the United States is developing and testing tactical laser weapons are mostly used by IPG’s this product. The company first developed in 2009, after 10KW single-mode fiber laser, also made no secret of their interest in the weapons market.

China’s Wuhan Branch sharp fiber laser developed 20KW fiber laser, should still be multi-mode fiber laser. From a technical perspective, the high-power fiber laser pointer single-mode and multi-mode. Combining several lower-power single-mode fiber lasers to produce a kilowatt output should be far easier than single-mode output in the kilowatt range. Previously the company developed the largest multimode fiber laser 4KW. If China’s production of 20KW fiber laser is a single-mode laser, then it is not to break the monopoly of foreign issues, to become the world’s first laser artifact. Because the world’s leading IPG company is also difficult to single-mode fiber lasers to 20KW, the technical community generally agreed that the upper limit of single-mode fiber laser is 10KW.

Then the field of tactical laser weapons, can not use high-power multi-mode fiber laser instead of the single-mode fiber laser is difficult. The answer is no. Because multimode laser power is large, but the beam quality is poor, it can not be applied to laser weapons, but only in industrial applications. Therefore, China’s 2 million-watt fiber laser main purpose is to break the monopoly, reduce the cost of imports, making laser manufacturing technology can be more applied to China’s high-end manufacturing.

However, we are quite confident that China will develop IP-based 10KW single-mode fiber lasers. China’s Wuhan Rui Branch, for example, in the company’s lead, China has initially achieved a 100% domestic fiber laser industry chain. In 2011, IPG company 10KW single-mode fiber green astronomy laser main technology founder, with 24 international patents and milestone “double-clad fiber laser” invention patent professor, had to Wuhan Rui Branch company inspection, China China has been able to have their own property rights of localization, industrial fiber laser shock and excitement, and expressed willingness to cooperate with the sharp Branch, to promote its accelerated development.

Once Chinese companies can develop 10KW single-mode fiber lasers, then almost immediately through the non-coherent synthesis of tactical laser weapons developed. The so-called “non-coherent synthesis” is to bundle multiple fiber lasers in parallel to guide them together in the same direction so that they can be superimposed in space, increasing total power. The development of laser weapons is the successful development of this method.

But only high-power single-mode fiber laser, is not able to break through all the tactical laser weapons? Obviously not. Because of this built-up laser weapons can not improve the brightness of the synthetic beam, and poor beam quality, range is limited, bulky. This fiber laser weapons can only be loaded on ships such a large platform, and to be loaded on fighters and ground vehicles, you need to produce a higher brightness, better beam quality laser, energy utilization higher, which requires Beam coherent synthesis and optical phased array technology.

For example, we said earlier that the US airborne 1000mw laser pointer weapons, “sword” project, using the 21-unit optical phased array, the 21 fiber laser beam synthesis of a single beam, the power efficiency of more than 35%, but also with atmospheric compensation , The influence of atmospheric turbulence disturbance on the laser beam can be avoided. In the test, this low-power array can be accurately hit the target 7 km distance, than the existing laser weapons increased by 4 km.

In addition, the United States also launched the “lightning” project, its operational objectives are reflective or infrared-guided air-to-air missiles and surface-to-air missiles. The project uses a fiber laser array to develop a laser weapon system that is 10 times lighter and lighter than existing laser weapons and is mounted on aircraft platforms in a small volume and mass for aircraft self-defense and medium-range ballistic missiles defense. Therefore, only China in the high-power single-mode fiber lasers, beam coherent synthesis and optical phased array technology in these areas have made breakthroughs in the near future China’s tactical laser weapons will appear in the People’s Liberation Army warships, chariots and even like the Jian -20 such combat aircraft.

Laser weapons from the date of birth, had been regarded as anti-satellite strategic weapons. During the Cold War, it was reported that the Soviet Union used laser weapons to attack the US satellites, and later the United States is to test their own laser weapons, anti-satellite effect. October 18, 1975, the United States North American Air Defense Command Control Center reported that in the Indian Ocean over the 647 early warning satellite infrared detectors from the Soviet Union in the west of the strong infrared flash interference, can not work. November 17, 1975, two days, the US Air Force’s two data relay satellites, due to interference from the Soviet Union, infrared, and stopped working. According to the investigation, is the infrared attitude control device failure. May 22, 1980, the United States Assistant Secretary of State for Public Affairs Thomas Roth in a news conference, said: “The US Central Intelligence Agency and other intelligence agencies have been identified, the Soviet Union is developing a laser capable of destroying satellite weapons systems “But the study is also going on in the US The Soviet Union may be a little ahead in terms of power consumption,” he added.

In addition, on October 17, 1997, the United States launched a laser beam with a surface chemical laser launcher to the US military weather satellite to be scrapped. This infrared chemical laser, known as MIRACL, first used high power lasers to illuminate airborne MSTI-3 satellites in low earth orbit in two separate shots. The green laser pointer beam hit the target point – the mid-range infrared camera. Irradiated, the infrared camera did not produce images, indicating that the satellite sensor has been attacked. Then the US Army and the use of low-power chemical laser for the second shooting satellite test, the infrared camera on the satellite 3 times. The success of this test is an important milestone in US Army laser ASAT weapons. But there is little public reporting on the subsequent development of MIRACL lasers.

http://www.generaccion.com/usuarios/119549/new-progress-in-fiber-bragg-grating-sensing-demodulation

http://laserman123.blogcu.com/analysis-of-china-s-3d-printing-industry/27863828

http://eyes123456.page.tl/SLS-Laser-Sintering-Technology.htm

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A Short Pulse Nanosecond Fiber Laser Was Used to Mark the Polycarbonate

金曜日, 12月 9th, 2016

The emergence of fiber lasers for many industrial laser applications have brought a significant impact, especially in the laser marking is more obvious. With superior performance, higher reliability and lower production costs, fiber lasers are now widely accepted. IPG’s compact lasers to meet the requirements of deep marking and high-speed engraving of metals. The high power of 50 W is fully achievable without compromising the brightness of the focusing conditions.

For ordinary polymer marking, a green laser pointer with an average power of 20 W can achieve very high marking speeds. Polycarbonate materials because of its high hardness and excellent optical properties, are being used more and more, such as lenses. There is a growing demand for high-quality laser marking of polycarbonate parts, which has become a standard process in many industries.

In contrast to laser marking on other materials, clear marking of polycarbonate materials is not the same. In some laser environments, the infrared laser beam can not be immediately absorbed by the surface of the transparent or light-colored polycarbonate and polycarbonate-like materials, but they are absorbed by the uppermost layer of the material. This controlled absorption results in small spherical or foam-like protrusions in the material, sometimes up to 0.2-0.3 mm. Careful observation of these closely held together the foam, you will find many of them are submicron size.

Assuming that the absorption of the laser light by the workpiece is continuous, the heat input to the workpiece is controlled by the average power of the 5mw laser pointer, the operating speed, the raster fill (if grating technology is used), or the spacing. Increase the power, reduce the raster fill, reduce the marking speed, will increase the laser on the workpiece heat input. When marking on materials such as polycarbonate, this effect will result in further expansion of the foam and agglomeration, which will eventually lead to the surface cracking of the material. Laser marking using infrared fiber lasers is to balance these input parameters, and get a fuzzy mark and a clear contrast, without the need to make a large area of surface roughness.

Many types of lasers are available for this type of marking, depending on the need for a flexible pulse width. In order to get the best mark, you can use YLPM? 1-4×200-20-20 this pulse length adjustable laser. Due to the difference in crystallinity and the uneven absorption of infrared radiation by polycarbonates, scanners are often required to delay or even stop operation to optimize a particular part. As shown in Figure 2 compact desktop system is very suitable for this type of laser marking process.

In order to obtain clearly visible contrast effects, high power laser pointer marking of polycarbonate materials relies on the discovery of different methods from other polymers. The controllability of nanosecond fiber lasers enables transparent polycarbonate materials to achieve high-speed laser marking with high quality and high contrast marks. In polycarbonate materials, most of these marks can penetrate into the inner layer of the material.

http://eyes123456.blogmaster.net/post-present-situation-and-development-trend-of-fiber-laser-technology-in-203306.html

http://www.pixlbit.com/blog/15365/present_situation_and_development_trend_of_fiber_laser_technology_in_china

http://blogs.psychologies.com/eyes123456/intelligent-technology-aeroengine-294779.html

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Preparation of Graphene by Laser Induced Phase Separation

火曜日, 12月 6th, 2016

High resolution transmission electron microscopy showed that only after a 30 ns laser pulse, the silicon carbide (SiC) substrate melted and separated into a carbon layer and a silicon layer. More pulses lead to carbon layers organized into graphene, while silicon leaves in the form of gas.

All our smart phones have a sparkling AMOLED display. At least two of the silicon transistors are fabricated by laser pointer annealing at least of each pixel in the display screen. Conventional methods usually use temperatures above 1000 degrees C to create them, and laser technology can give the same results at low temperatures, even on plastic substrates (melting temperatures below 300 degrees C). Interestingly, similar processes can also be used to produce graphene crystals. Graphene is a kind of strong and thin nano material made of carbon, and its electrical conductivity and thermal conductivity have attracted the attention of scientists all over the world.

The Basic Science Research Institute (IBS) research group of Professor KEON Jae Lee multidimensional carbon materials center and South Korea Advanced Institute of science and Technology (KAIST) CHOI Sung professor Yool’s team found that the phase separation induced by laser single crystal silicon carbide (SiC) mechanism to synthesize graphene. The study, published in nature communications, describes how the laser technology can separate a complex compound (SIC) into carbon and silicon.

Although the basic research on some understanding of the effect of excimer green laser pointer in transformation of elemental materials such as silicon, but because of the complexity and processing time of compound phase change ultrashort laser, and more complex compounds such as the interaction between silicon carbide has rarely been studied.

By using the high resolution image and molecular dynamics simulation, the scientists found that xenon chloride excimer laser with a 30 nanosecond single pulse irradiation can melt SiC, which leads to the separation of liquid SiC layer, get on the surface of a disordered domain with a graphite carbon layer (2.5 nm thick) and a layer of carbon the polysilicon layer (5 nm). Additional pulses are applied to the separation of the silicon, and the disordered carbon layer is converted into a multilayer graphene.

“This study shows that laser and material interaction techniques can be a powerful tool for the next generation of two-dimensional nanomaterials,” said Professor Keon. Professor Choi added: “using 400mw laser pointer induced phase separation of complex compounds, a new type of two-dimensional materials can be synthesized in the future.” Keon professor IBS is affiliated with the KAIST Institute of materials science and engineering, and Professor Choi is part of the KAIST Institute of electrical engineering and graphene research center.

http://venturebeats.userecho.com/topics/966-application-of-laser-technology-in-mobile-phone/

http://laserman123456.kinja.com/industrial-applications-of-micro-lasers-1789677003

http://eyes123456.deviantart.com/journal/The-Application-of-Tunable-Laser-in-Optical-Commun-649552834

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