Laser amplification by stimulated emission of light, in comparison with traditional light sources, it is characterized by four distinct orientation, brightness, color is strong, coherent and well. Laser has a good time and space characteristics of the focus after the power density of up l05W/cm2 above, the material on the role of either type in a row, and may be quasi-continuous, but also the pulse. Pulse width can be as short as μs, ns, and even shorter: its role in the material on the size, shape, power (or energy) can facilitate the adjustment. 1.06μm wavelength of the YAG laser can also use optical transmission, the kilowatt-class YAG laser optical fiber transmission at the time of the diameter of only a few hundred μm, these features of laser welding and its related fields such as cutting, drilling, marking, melting Review and other areas has been growing a wide range of applications, and to be more and more attention.

In addition, the laser light is also generally the same as the biological effects of such biological effects may be on the one hand, to the benefit of mankind, such as breeding, health care, on the other hand, no radiation protection of high-power laser, the result of human tissue will be, directly or indirectly, Damage. As a result, laser understanding of the organism may cause injury to the workers engaged in laser welding is very necessary.

1 of laser biological effects

Laser effects on living organisms of the main effects of heat, light effects, as well as the effect of pressure on the effects of electromagnetic fields.

1.1 Effect of Heat

Heat is the effect of high power density of laser radiation caused by the organism when the organism of the Organization of protein damage, burns, charring, gasification, piercing and so on.

Research showed that 100 joules of laser 0.1cm3 to the organism, in a few μm period of time may be warming up to 200 ¡æ. However, the drop in temperature is very slow pace, the sharp rise in temperature will cause mild cold gene mutation. Under normal circumstances, gene by about 1,000 atoms, and atoms will be affected by high fever to change its position and become a heterogeneous elements.

1.2-optic effect

Is the laser caused by the organism to stimulate, and inhibit, as well as the role of decomposition and so on, the laser light on the human body and the effect of laser wavelength, the exposure time, radiation dose and so on.

1.2.l photosensitive role

Refers to laser-organisms on the inhibition or stimulation. He-Ne laser wavelength of the 0.6328μm, mw-He-Ne laser as the body temperature rise on almost no sense, however, can stimulate activity and enhance the phagocytic cells in the blood, red blood cells and hemoglobin levels.

l.2.2 photo-induced damage

A high degree of monochrome laser will make the chemical bond in molecular excitation caused by the decomposition of molecules. For example Ribosomal 0.25 ~ 0.26.μm acid absorption of ultraviolet light lead to cell death.

1.2.3 pressure effect

Light objects in the light of the momentum transfer to the objects that form a light pressure, light and power density is directly proportional to pressure. Laser pressure from two aspects of radiation pressure, when the power density: 108 W / cm 2, the radiation pressure of up to 3400 Pa, the second is the power density of more than damage the body's threshold, the Organization evaporation, gasification The impact of pressure. The impact of radiation pressure and the pressure form the pressure of the total.

l.2.4 effects of electromagnetic fields

Normal body cells and tissues are free of charge a certain reserve, there is a special biological field. Laser as a very strong electromagnetic waves, the exposure of human tissues, the electromagnetic fields on human tissue interfere with the biological field, the impact of their physiological state.

Laser light of the effects of electromagnetic fields of the main body of atoms and molecules, in turn affect the biological potential, biological potential of nerve impulse transmission has an important role, therefore, give rise to laser radiation by stimulating the nerve impulse transmission, suppression or destruction.