(a) a directional light
Ordinary light is light in all directions. To emit light travels in one direction, need certain condenser device fitted on the light source, such as the car's headlights and the searchlight is equipped with concentrated role reflector, the radiation light together in one direction. The launch of the laser, laser are born in one direction, beam emittance of tiny, only about 0.001 radians, close to parallel. In 1962, the first human to use laser to the moon, the earth from the moon's distance is about 380000 kilometers, but the laser in the light of the moon in less than two kilometers. If the focusing effect is very good, seems to parallel the searchlight beams fired at the moon, according to the spot diameter will cover the entire moon.
(2) high brightness
Before the invention of laser, high-voltage pulsed xenon lamp has the highest brightness in the artificial light, and the sun's brightness, and ruby laser laser brightness, more than tens of billions of times the xenon lamp. Because of the brightness of the laser is extremely high, so can illuminate distant objects. Produced by the ruby laser beams fired on the moon is about 0.02 lux (light), color red, the laser spot visible. If use the power of the strongest searchlight on the moon, only about one over one trillion of lux, the human eye cannot perceive. The main reason for the laser light is a directional light. A large number of photons is concentrated in a small range of space, natural high energy density.
(3) the very pure color
The color of the light is determined by the light wavelength (or frequency). Certain wavelengths corresponding to a certain color. The wavelength range of sunlight about 0.76 microns to 0.4 microns, and the corresponding color from red to purple, a total of 7 kinds of color, so the sun not monochromaticity. Launch a single color of light source is called monochromatic light source, light waves, it is a single wavelength. Such as krypton lamp, lamp of helium, neon, hydrogen light is monochromatic light source, such as fire only one color of light. Monochromatic light wavelengths of light, while a single, but there is still a certain distribution. If krypton lamp fire only red light, good monochromaticity, known as the crown of monochromaticity, still have the range of 0.00001 nm wavelength distribution, so the krypton lamp emit red light, identify carefully if still contains dozens of red. Thus, the wavelength of optical radiation distribution range is narrow, monochromaticity, the better.
The wavelength of light, laser output distribution range is very narrow, so very pure color. With the output red light he-ne laser as an example, the wavelength of the light distribution can narrow the 2 x 10 to 9 nm, the launch of the red light is krypton lamp two over ten thousand of the wavelength range. Thus, the monochromaticity of laser is far more than any kind of monochromatic light source.
In addition, there are other features: the laser coherence is good. Laser frequency and direction of vibration, highly consistent phase, make laser light waves in space overlap, overlapping OuDeGuang intensity distribution will be stable and strong and weak phenomenon. This phenomenon is called interference of light, so the laser is coherent light. And ordinary light source the light, its frequency, vibration direction, phase, called incoherent light.
Flash can be a very short time. Due to technical reasons, ordinary light flash could not have a short time, camera with flash, flash time is about one over one thousand of a second. Pulsed laser flash time is very short, can reach 6 femtosecond (1 femtosecond = 10 to 15 seconds). Flash time very short light source in the production, scientific research and military has important use.
(4) the energy density is great
The photon energy is calculated using E = hf, which h as the Planck constant, frequency of f. Therefore, the higher the frequency, the higher the energy. Laser frequency range 3.846 * 10 ^ (14) Hz to 7.895 * 10 ^ (14) Hz. Electromagnetic spectrum can be roughly divided into: (1) the radio waves - wavelength from thousands of meters to 0.3 meters, general in this wave, television and radio band; (2) microwave wavelength - from 0.3 m to 10-3 meters, the wave multi-purpose in radar or other communication system; (3) infrared wavelength - - 3 meters from 10 to 7.8 x 10-7 meters; (4) the visible light - this is what people can is a narrow band of light. From 780-380 nm wavelength. Was the motion of the electrons of the atoms or molecules in change of electromagnetic waves. Since it is the feelings we can directly detect the electromagnetic waves that part of the few; (5) wavelength uv - from 3 x 10-7 to 6 x 10-10 metres. The causes of these waves and light waves, often at the time of discharge. Because of its energy and general chemical reactions involved in the size, so the effect of ultraviolet light chemical strongest; (6) x ray - this part of the electromagnetic spectrum, the wavelength from 2 x 10 to 9 meters to 6 x 10-12 m. X ray (X-ray) is the atomic inner electron electric by a state or state to jump to another given out by the electrons in the atom nuclear power field slows down; (7) gamma rays - the wavelength from 10-10 ~ 10-14 meters of the electromagnetic waves. The invisible electromagnetic wave emitted from the nucleus, radioactive substances and has a tendency to this radiation is accompanied by nuclear reactions. Gamma ray penetration is very strong, the creature's damage is very large. It seems that the laser energy is not very big, but it is a big energy density (because its scope is very small, usually only one point), gathered a lot of energy in a short period of time, used as weapons, can understand.
Laser processing technology is the use of the characteristics of the interaction between laser and material on the material (including metal and nonmetal) for cutting, welding, surface treatment, punching, micro machining, and as the light source, such as object recognition of a foreign technology, the traditional application of the largest fields for laser processing technology. Laser technology is involved in optical, mechanical, electrical, materials and testing different subjects, such as, a comprehensive technology, the traditional point of view, the scope of its research in general can be divided into:
1. The laser processing system. Including laser, light system, machine tools, control system and testing system.
2. Laser processing technology. Including cutting, welding, surface treatment, punching, marking, marking, trimming, etc. Various kinds of processing technology.
Laser welding, automotive body thickness plate, automobile parts, lithium batteries, sealing devices such as cardiac pacemaker, sealed relay, and various don't allow the deformation of welding pollution and device. Currently used laser YAG laser, CO2 laser and semiconductor pump laser.
Laser cutting: automotive industry, computer, electrical cabinet, wood die cutter, cutting various metal parts, and special materials, circular saw blades, the force that press a gram, spring washers, electronic parts under 2 mm with some metal plates, steel pipes, tin-coated copper plate, plate, lead plate, phosphor bronze plating, electricity boards, thin aluminium alloy, quartz glass, silicon rubber, below 1 mm alumina ceramic pieces, aerospace industry use of titanium alloy and so on. Using laser YAG laser and CO2 laser.
Laser marking: in all kinds of materials and almost all industries are widely used, is using laser YAG laser, CO2 laser and semiconductor pump lasers.
Laser drilling, laser drilling is mainly used in aerospace, automobile manufacturing, electronic instrument, chemical industry, etc. The rapid development of laser drilling, mainly reflected in the punching with YAG laser average output power has been five years ago from 400 w to 800 w to 1000 w. Domestic laser drilling mature application is currently in the production of synthetic diamond and natural diamond die and clocks and instrument jewel bearing, the plane leaves, in the production of multilayer printed circuit boards and other industries. Currently used laser is given priority to with YAG laser, CO2 laser, there are also some excimer laser, laser and semiconductor pump laser isotope.
Laser heat treatment: widely used in the automotive industry, such as cylinder liner, crankshaft, piston ring, commutator, gear parts such as heat treatment, at the same time in the aerospace, machine tool industry and other machinery industry is also widely used. Application of laser heat treatment in our country is far more expansive than abroad. Many of currently used laser YAG laser, CO2 laser is given priority to.
Laser rapid prototyping, the laser processing technology and computer numerical control technology and combined to form a flexible manufacturing technology. Many used for mould and model industry. Currently used laser is given priority to with YAG laser, CO2 laser.
Laser cladding: widely used in aerospace, mould and mechanical and electrical industry. Currently used laser is given priority to with high-power YAG laser, CO2 laser.
Applied to the dental laser system
According to the different effects of laser applications in dentistry, divided into several different laser systems. Difference is one of the important features of the laser, the wavelength of light, different wavelength of laser to the organization, in the range of visible light and near infrared spectrum of light, low light absorption, strong penetrability, can penetrate into the deeper parts of the body tissue, such as argon ion laser, diode laser, or Nd: YAG laser (figure 1). The Er: YAG laser and CO, laser light penetrability is poor, can only through tooth tissues for about 0.01 mm. Difference is the second important characteristic of the laser, laser intensity (power), such as applied in the diagnosis of diode laser, its strength is only a few milliwatts, it sometimes can also be used in laser display.
Used in the treatment of the laser, the moderate intensity laser is usually a few watts. Laser effect to the organization, but also depends on the means of transmission, laser pulse in a typical continuous laser pulse means of transmission are: argon ion laser, diode laser, CO2, laser; To launch by way of short pulse laser are: Er: YAG laser or a number of Nd: YAG laser, the strength of the short pulse laser can achieve 1000 watts or higher (i.e., power), the intensity is high, the laser light absorption is high also, applies only to remove hard tissues.
Application of laser in caries diagnosis
1. Take off mine, shallow caries
2. The hidden caries
Application of laser in the treatment
1. The cutting
2. The fillings of polymerization, nest hole processing
(1) laser has been widely used in beauty field use. Laser is produced by high energy, focusing on precision, has certain penetration of monochromatic light, the effect on human tissue and high heat generated by the locally so as to achieve the aim of remove or destroy target groups, different wavelength of laser pulse can cure all kinds of vascular dermatosis and pigmentation, such as the nevus of ota, nevus flammeus, freckles, age spots, capillary expansion, etc., and go to the tattoo, wash eyes, wash eyebrow, treatment of scar, etc.; In recent years, some new types of lasers high-energy ultra pulse CO2 laser, erbium laser anti-wrinkle, exfoliating skin, the treatment of snoring, whitening teeth and so on, has obtained the good curative effect, open more and more wide field of laser surgery.
(2) laser surgery have the incomparable superiority to traditional surgery. First laser surgery does not need hospital treatment, small incision, intraoperative bleeding, not light trauma, no scar. Bags, for example, the treatment of the traditional operation method for wide scope of stripping, intraoperative bleeding, postoperative healing slowly, scarring disadvantages such as easily, and the application type high-energy ultra pulse CO2 laser treatment eye bags, with intraoperative bleeding, it does not need to suture, does not affect the normal work, surgical site light edema, rapid recovery, no scar, can't compare with traditional surgery. And some because of the bleeding to the endoscopic surgery, more can be done by laser cutting instead. (note: there is a certain adaptation range),
(3) the laser in the treatment of vascular dermatosis and pigmentation effect is remarkable. Using pulsed dye laser treatment of nevus flammeus, curative effect is distinct, the surrounding tissue damage is small, almost no scar. Its emergence as a revolution in the history of nevus flammeus treatment, because nevus flammeus treatment history, such as radiation, freezing, electric bright, operation method, the high incidence of scar, and often appear a disfiguring or calm. Laser treatment of vascular dermatosis is the use of oxygenated hemoglobin in a certain wavelength of laser selective absorption, and lead to the height of the vascular tissue damage, it has high accuracy and safety, do not affect the surrounding adjacent tissue. Therefore, laser treatment of capillary expansion is also curative effect is distinct.
In addition, due to the variable pulse laser appeared, such as make unsatisfied tattoo removal, and all kinds of pigmentary dermatosis such as nevus of ota, got a major breakthrough in the treatment of senile plaque. This kind of laser according to the selective effects of field theory, (i.e., different wavelength of laser can be selectively applied to different color of skin damage), using its powerful instantaneous power of radiation energy of highly concentrated and selective pigment, extremely short pulse width, the laser energy concentrated on the pigment particles, its direct evaporation, smash, out of the body through the lymphatic organization, without affecting the surrounding normal tissues, and its curative effect, safe and reliable, no scar, pain small and deeply rooted in the hearts of the people.
(4) laser surgery inaugurated a new era of medical hairdressing. High-energy ultra pulse CO2 laser exfoliating skin opens up a new technology of cosmetic surgery. It USES high-energy, extremely short pulse laser, the aging, damage skin tissue by vaporizing instantly, and does not hurt and surrounding tissue, little hemorrhage treatment process, and can accurately control the depth. The effect by international medical cosmetic surgery sector and is known as "ushered in a new era of medical hairdressing"; In addition, the more energetic ultra pulse CO2 laser treatment eye bags, snoring, and even laser teeth whitening, etc., for its safe and accurate curative effect, simple and quick treatment in the medical cosmetic industry created a miracle after another. Laser cosmetic makes medical hairdressing, a big step forward, and assigned to the connotation of medical hairdressing update.
Laser radar, laser radar) refers to the radar using laser as a radiation source. Laser radar is a combination of laser technology and radar technology. By the transmitter, antenna, receiver, tracking and information processing and other parts. Transmitter is all kinds of laser, such as carbon dioxide laser, neodymium-doped yttrium aluminum garnet laser, semiconductor laser and wavelength tunable solid state lasers, etc. Antenna is optical telescope; Receiver used in a variety of forms of photoelectric detector, such as the photomultiplier tube, semiconductor photoelectric diode, avalanche photodiode, infrared and visible light detector etc. Laser radar using pulsed or continuous wave 2 kinds of works, direct detection and heterodyne detection detection points.
Laser radar, laser radar) refers to the radar using laser as a radiation source. Laser radar is a combination of laser technology and radar technology. By the transmitter, antenna, receiver, tracking and information processing and other parts. Transmitter is all kinds of laser, such as carbon dioxide laser, neodymium-doped yttrium aluminum garnet laser, semiconductor laser and wavelength tunable solid state lasers, etc. Antenna is optical telescope; Receiver used in a variety of forms of photoelectric detector, such as the photomultiplier tube, semiconductor photoelectric diode, avalanche photodiode, infrared and visible light detector etc. Laser radar using pulsed or continuous wave 2 kinds of works, direct detection and heterodyne detection detection points.