(A) directional light
Ordinary light is light in all directions. Make the emission of light propagation in one direction, you need to light a certain condenser fitted with devices such as car headlights and searchlights were installed on the role of the condenser mirror, so that radiation is to bring together in one direction injection. Laser emission of the laser, born in one direction injection, beam divergence is extremely small, only about 0.001 rad, close to parallel. In 1962, the first human use of laser irradiation the moon, the moon's distance from the Earth about 38 million km, but the laser spot on the lunar surface less than two kilometers. If condenser works well, seemingly parallel to the searchlight beam fired at the moon, according to its spot diameter will cover the entire moon.
(B) high brightness
Before the invention of the laser, artificial light in the high-voltage pulse xenon lamp brightness highest, comparable with the brightness of the sun, while the ruby laser the laser light, xenon lamp can exceed several hundred billion times. Because the laser is extremely bright, they were able to illuminate distant objects. Ruby laser beam emitted illumination produced on the moon is about 0.02 lux (unit of illumination), the color red, visible laser spot. If the most powerful searchlight with power moon light, the resulting illumination is only about a trillionth of Lux, the human eye can not detect. The main reason is the high brightness of laser light directed. A large number of photons concentrated in a very small space within the injection, the natural high energy density.
(C) very pure color
The color of light from the light wavelength (or frequency) decision. Corresponds to a certain wavelength of a certain color. Wavelength distribution of sunlight in the range of about 0.76 microns to 0.4 microns, corresponding to the color from red to purple, a total of seven colors, the color of sunlight alone. Launch of single color light source as monochromatic light source that emits a single wavelength of light. Such as krypton lamp, helium lamp, neon, hydrogen and other light sources are monochromatic, only a certain color of light emission. Although monochromatic single wavelength light source, but there is still a certain distribution. Such as krypton lamp only transmit red color is very good, known as the color of the crown, the wavelength range of the distribution is still 0.00001 nm, the krypton lamp is red, if carefully identify still contains dozens of red . Thus, the distribution of optical radiation wavelength range of the more narrow, monochromatic as possible.
Output of the laser light, a very narrow wavelength distribution, so very pure color. The output of red helium-neon laser, for example, the wavelength of the light distribution can be narrow to 2 × 10-9 nm krypton lamp emits a red light is the wavelength distribution range of ten thousandths. Thus, the laser is far more than any kind of monochrome monochromatic light.
In addition, there are other characteristics of the laser: coherent good. Laser frequency, the vibration direction, phase high degree of consensus, the laser light waves overlap in space, the overlapping area of the light intensity distribution of the strength and stability will be white phenomenon. This phenomenon is called light interference, so the laser is coherent light. Ordinary light source of light, its frequency, the vibration direction, phase inconsistencies, called non-coherent light.
Flash time can be very short. Due to technical reasons, ordinary flash light can not be a very short time, camera with flash, flash is a thousandth of a second time around. Pulsed laser flash time is very short, up to 6 femtoseconds (1 femtosecond = 10-15 seconds). Flash of light in a very short time to production, scientific research and have important military uses.
(D) energy density greatly
Photon energy is E = hf to calculate, where h is Planck's constant, f is frequency. It can be seen, the higher the frequency, the higher the energy. Laser frequency range 3.846 * 10 ^ (14) Hz to 7.895 * 10 ^ (14) Hz. The electromagnetic spectrum can be broadly divided into: (1) radio waves - the wavelength from several kilometers to 0.3 meters, the general television and radio broadcast band is to use this wave; (2) Microwave - wavelengths from 0.3 m to 10-3 m, these waves is used in radar or other communication systems; (3) infrared - wavelengths from meters to 7.8 × 10-3 10-7 m; (4) visible light - which is very sensitive people can narrow a band. Wavelengths from 780-380nm. Just inside the atom or molecule changes the electronic state of motion of electromagnetic waves emitted. As it is we can directly experience the rarely aware that part of the electromagnetic wave; (5) ultraviolet - wavelengths from 3 × 10-7 m to 6 × 10-10 meters. These waves and light waves similar to causes, often issued in the discharge. Because of its energy and general chemical reactions involved in energy in size, so the chemical effects of UV strongest; (6) roentgen - this part of the electromagnetic spectrum, wavelengths from 2 × 10-9 m to 6 × 10-12 meters. Roentgen (X-ray) is the power of the inner electrons by an atom can jump to another state to state or deceleration of electrons in the nucleus when the electric field emitted; (7) γ-rays - is the wavelength of from 10-10 ~ 10-14 meter waves. This invisible electromagnetic waves are sent from the nucleus to the radioactive material or nuclear reactions are often accompanied by such a radiation issue. γ-ray penetration is very strong, very destructive to the biological. Seen in this light, laser energy is not great, but its energy density is large (because of its scope is very small, usually only one point), a short time gathered from a lot of energy, it can be used as weapons understand.
Laser processing technology is the use of laser beam interaction with the material properties of the materials (including metal and nonmetal) for cutting, welding, surface treatment, drilling, micromachining, and as the light source, object recognition such as a technology, legacy applications the largest areas of laser processing technology. Laser technology is related to the optical, mechanical, electrical, materials and testing and many other subjects of an integrated technology, the traditional point of view, the scope of its research can be divided into:
1 laser processing system. Including lasers, optical systems, machine tools, control systems and detection systems.
(2) laser processing. Including cutting, welding, surface treatment, drilling, marking, scribing, trimming and other processes.
Laser welding: thickness of auto body panels, car parts, lithium battery, a pacemaker, sealed relays and other sealing devices and a variety of contamination and deformation does not allow welding device. Currently used lasers YAG lasers, CO2 lasers and diode-pumped lasers.
Laser cutting: the automotive industry, computers, electrical cabinet, wood cutting die industry, metal parts and special materials, cutting, circular saw blade, acrylic, spring pads, 2mm below the electronic parts with copper, some of the metal stencil, steel, tin iron, steel-plated lead Asia, phosphor bronze, bakelite, thin aluminum, quartz glass, silicon rubber, 1mm the following alumina ceramic, titanium alloys used in aerospace industry and so on. Using lasers with YAG laser and CO2 laser.
Laser Marking: In almost all industries and all kinds of materials are widely used, currently used lasers with YAG lasers, CO2 lasers and diode-pumped lasers.
Laser Drilling: Laser drilling is mainly used in aerospace, automobile manufacturing, electronic instruments, chemical industry. The rapid development of laser drilling, mainly in the hole with a YAG laser average output power from 5 years ago to the 800w to 400w 1000w. The relatively mature domestic application of laser drilling in the artificial diamond and natural diamond drawing die of watches and instruments of production and jewel bearings, aircraft blade, multi-layer printed circuit board industries such as manufacturing. Mostly currently used lasers YAG laser, CO2 laser-based, there are some excimer lasers, isotope lasers and diode-pumped lasers.
Laser heat treatment: widely used in the automotive industry, such as cylinder liner, crankshaft, piston rings, commutator, gears and other parts of the heat treatment, while in aerospace, machine tools and other machinery industry is also widely used. China's application of laser heat treatment is much broader than abroad. Mostly currently used lasers YAG laser, CO2 laser-based.
Rapid Prototyping: the laser processing technology and computer numerical control technology and flexible manufacturing technology are combined to form. Used for mold and model industry. Mostly currently used lasers YAG laser, CO2 laser-based.
Laser coating: In aerospace, mold, electrical and mechanical industry widely. Mostly currently used high-power YAG laser, laser, CO2 laser-based.
