Standards and measures for the safety and protection of lasers

Source：China laser network   Time：2016-04-09   Edit：SunyLaser

 1 laser safety standards
After the birth of the laser in 1960 and 1963, have people according to the measured the retina and skin damage threshold of laser maximum permissible exposure, then the world appeared numerous safety standard of second, 30 kinds of above (the American most), but in understanding the operating threshold (is under a microscope to check cell injury by is with the ophthalmoscope can see damage or perceived visual function decline), damage threshold is according to the responses to acute or chronic reaction, the safety factor is 10 or 1000 and other reasons, the proposed safety standards vary greatly.
1.1 National Standards Institute (ANSI) laser safety committee
For safe use of lasers and to reduce the confusion, National Standards Institute (ANSI) set up laser safety committee, the power of organization. Through research, in 1973 published the National Standard Association "laser safety use Z-136, 11973" safety standards.
In order to use the laser safety of wavelength 0.2 ? m ~ 1mm, recommended reasonable and appropriate security guidelines, the committee according to laser laser beam is strong to be able to the eye or skin damage, the lasers are classified into five categories, for example, first class because of power density is small, do not need protection, the fifth class must placed under the most stringent control. This booklet discusses the hazards of evaluation and classification, control measures, laser safety plans, medical supervision, other hazards, eye and skin radiation criteria, as well as laser parameters measurement and other aspects of the problem.
Lasers can damage the eyes, skin, respiratory tract, central nervous system, and the whole body. At present, only the eyes and skin are generally put forward safety standards. In view of the laser currently used for mechanical processing, to the possibility of respiratory tract damage in growth, the worker has the possibility of laser chronic radiation hazards also in growth, so the harm of laser to the above five aspects should pay attention.
1.2 laser safety standards in China
Several standards have been set up in the field of laser safety in our country:
(1) GB7247-87 "radiation safety of laser products, equipment classification, requirements and user's Guide". National Bureau of standards issued in October 1, 1987, February 9, 1987 implementation.
(2) 10320-88 - GB "laser equipment and the implementation of electrical safety". The National Technical Supervision Bureau released in January 1, 1990, December 30, 1988.
(3) GBl0435-89 "Hygienic standard for laser radiation in workplace". Ministry of health released in October 1, 1989, February 24, 1989 implementation.
(4) the national industry standard JB / T5524-91 "laboratory laser safety rules". Ministry of machinery and electronics industry, July 16, 1991 release, July 1, 1992 implementation.

 2 laser protection measures
As mentioned earlier, the laser is dangerous, but and electricity, as long as we don't careless, lightly, but strictly abide by the rules of safe operation, can harmlessly using laser to treat. Due to the various types of lasers have the need to pay special attention to the problem, so in addition to the general safety rules, on UV, visible, red and near infrared, far infrared and dye laser were put forward their eye, skin may cause damage and should take protective measures and safety standards, which will facilitate laser workers is the use of lasers to take protective measures, accomplish know fairly well, and need not indecisive.
(1) the harm and protection of far infrared laser: carbon dioxide laser used (10.6 m) for corneal absorption, can not enter the eye. As this kind of laser is not visible and the general power is larger, it will burn the cornea, conjunctiva and eyelids. For corneal burn. The light is little white cloud point, 10 min after irradiation involves only corneal epithelium, swollen, subsided, no visible scar, the heavier is cylindrical white scar that develops from the outside to the inside, again heavy is the formation of ulcer scar or perforation. Although powerful, but the door is quite simple, just wear a pair of flat glass glasses. Carbon dioxide laser threshold value is 0.1W / cm2. Carbon dioxide laser absorption for 0.2mm thick skin, it is easy to cause blisters or burns. Because the power is larger, it will burn at once, physiological reaction (such as pain) can not protect the role of. Cross stimulated atmospheric pressure carbon dioxide laser can make air ionization. If using 30mJ as carbon dioxide forearm surface skin 0.5 ~ 0.25s, spot diameter 10 m, irradiation tingling and burning. Erythema appeared after a few hours, 24h after the expansion, edema, finally synulosis. Protective measures wear gloves.
(2) general protection measures: the laser should be closed up. In addition to the laser beam, the laser beam should not leak outside the target. Laser beam should not be at the same level as the eye. Laser beam should be limited to no reflection and fire prevention materials. Pulse laser should have safety gate to prevent laser explosion. For each application, it should be used to achieve the minimum level of radiation.
The laser room walls can not be blacked out, using light and diffuse coatings to reduce mirror reflection and improve light. Interior should be bright to narrow the pupil. Also should be well ventilated, so that xylene, carbon tetrachloride (cleaning), nitrogen (cooling), ozone concentration in the air does not exceed the permitted value. Interior furniture should be reduced to a minimum, the furniture surface should be rough. Irrelevant personnel are not allowed inside. Obstacles should be set, so that people can not go near the laser. Should be the same as the X-ray machine, high power laser work should be marked with a red light. The laser should be operated at a distance, and the operator should be operated in the next room.
All indoor personnel should wear the appropriate protective glasses. Do not use a mirror. The staff should wear overalls and gloves. To treat a laser like a gun, it is forbidden to look directly at the laser beam, as far as possible far away from the laser beam. Pay attention to high voltage operation rules to prevent electric shock (more than the laser damage reported by foreign shocks). Regular check eye. For the beginning of the workers should strengthen the laser protection education.
3 laser safety and protection
3.1 to take corresponding measures: (1) the Class-A lasers emitting laser does not cause any biological hazard, from having to take control measures; (2) class B laser belongs to the low power range, wavelength of 0.4 ~ 0.7 ? m power is less than 1MW and staring for a long time may cause damage to the retina. Therefore, to take protective measures and the use of warning signs; (3) C kind of laser power in the range; exposure time is short may biological damage caused by, therefore, control measures are essential. This kind of laser laser beam of diffuse reflection no harm; (4) class D laser is a high power range, can produce risk of a laser beam reflecting laser beam and human short-term direct or diffuse exposure will be caused by damage of biological, must take strict control measures.
3.2 seriously implement the safety work system: (1) laser operation places, such as laboratory, therapeutic room should have a high degree of lighting, so that the staff of the pupil to reduce, reduce the amount of laser into the eye. Indoor use white or light colored rough walls, reduce the specular reflection surface. In the laser room or doorway, the place where the laser beam is easy to reach the "laser danger" sign. The door panel direct gaze of staff, pay attention to staff (2) laser operation rules: a laser by laser safety education and training; B, wear protective glasses, and pay attention to the selection of a variety of specifications; C, the use of lasers after termination of the light path, open laser strictly abide by hydropower operation procedures; D, contact laser staff is not power or energy density exceeds the tolerance threshold of the main beam, and regular physical examination; (3) the relevant units must implement the laser safety protection measures, to set the security monitoring system; (4) laser production units of the class B lasers must be in the eye-catching position note "no look directly at the laser beam" in the words of warning signs and must cover. For class C and D laser must be with closed cover wrap the entire laser and installation safety interlock and lock key switch, laser triggered before the due warning signal, the panel prominently to note a warning sign. The physical parameters such as wavelength range, maximum output energy and power, pulse width, pulse repetition rate, beam divergence angle and so on are also available.