Careless, really blind --- Laser Safety Basics

Careless, really blind --- Laser Safety Basics

First, the domestic part of the standard laser safety aspects related to
1. "GB7247.1-2012 Safety of laser products Part 1: Equipment classification, requirements" ("Safety of laser products-Part 1: Equipment classification andrequirements", idt "IEC60825-1: 2007 Safety of laserproducts - Part 1: Equipment classification and requirements ", identical with" IEC60825-1: 2007 Safety of laser products - Part 1: Equipment classification and requirements ")
2. "GB / T 15706.1-1995 Safety of machinery - Basic concepts, general principles for design - Part 1: Basic terminology, methodology"
3. "GB / T 15706.2-1995 Safety of machinery - Basic concepts, general principles for design - Part 2: Technical principles and specifications"
4. "GB / T 5226.1-2002 Safety of machinery - Electrical equipment - Part 1: General requirements"
5. "GB18490-2001 laser processing machinery safety requirements" (eqv "ISO 11553: 1996 Safety of machinery - Laser processing machines- Safety requirements")
6. "Electrical Safety GB10320-1995 laser equipment and facilities" (eqv "IEC 820: Electrical safety of laser equipment and installations")
7. "GBZ2.2-2007 Workplace Hazardous Occupational Exposure Limits Part 2: physical factors" (related to the laser radiation section)
Second, the maximum permissible exposure (MPE), accessible emission limit (AEL)
The maximum permissible exposure (MPE), accessible emission limit (AEL) is based on the classification of laser products.
The maximum permissible exposure (Maximum Permissible Exposure) is normally illuminated by the laser body does not produce adverse consequences of laser radiation levels.
MPE level can be without means or after prolonged eye or skin by irradiating the maximum radiation level in injury, which the laser radiation wavelength, pulse width or duration of irradiation, due to the dangerous state of biological tissue and exposed the 400nm ~ 1400nm visible and infrared laser radiation in the retinal image size and so on.
Accessible Emission Limit (Accessible Emission Limit, abbreviated AEL), the maximum allowable emission levels within a given category. It is usually obtained from the maximum allowable exposure (MPE).
Third, the classification of laser products
To facilitate laser product safety management, countries are to develop the appropriate classification standard for laser products. Our standard is "GB7247.1-2012 Safety of laser products Part 1: Equipment classification, requirements."
Since the wavelength of the laser beam energy range and pulse characteristics may involve a wide range, so use the degree of harm is very poor. According to the degree of harm, laser products are divided into classes 1, 1M, Class 2, 2M class, 3R class, 3B Class 4 category, a total of seven categories. The minimum degree of harm which Class 1, four categories of products the greatest hazard.
It is noteworthy that, it was in reference to laser products, they tend to use two, four other words, incorrect, should be Class 2, Class 4.
A) Class 1
Definition: During operation, in the corresponding emission wavelength and duration of human contact must not exceed a Class 1 laser radiation can reach emission limit (AEL) laser products.
Description: during use, including long time depending on the speed of light directly, even when using the optical observation instrument eye loupe with binoculars or binoculars by laser irradiation is still safe laser. Class 1 also includes a fully enclosed shield high power laser products, the use of the reach of potentially harmful radiation (embedded laser products), emit visible radiation energy beam within a Class 1 laser products may still produce stunning visual visual effects, especially in low light environments.
B) 1M class
Definition: in 302.5nm ~ 4000nm wavelength range, during the work, in the corresponding emission wavelength and duration of human contact up to laser radiation emission must not exceed Class 1 up to the limit (AEL) laser products.
Description: Includes the naked eye, in use for a long time directly into the beam, as the laser is safe, when using two optical viewing instruments (eye loupes or binoculars binoculars) one under the following conditions, exposure over MPE, and could cause Eye damage:
a) For the divergence of the laser beam, if the users in order to gather (collimation) the speed of light within an optical assembly is placed in a distance of 100mm from the light source;
b) For the collimated laser beam having a diameter larger than the diameter of the conditions specified measurement 3.
Class 1 laser wavelength range, limited to optical instruments translucent glass optical materials particularly good spectrum, namely between 302.5mm-4000mm, emit visible radiation energy beam Class 1M laser products may still produce stunning endoscopy visual effects, especially in low light environments.
C) Class 2
Definition: in a 400nm ~ 700nm wavelength range, during the work, in the corresponding emission wavelength and duration of human contact up to laser radiation must not exceed Class 2 reach emission limit (AEL) laser products.
Description: The product range of the laser emission wavelength of 400nm-700nm of visible radiation. Instantaneous irradiation is safe, but the laser beam may be interested in watching hazardous. Time reference for the 0.25s, this category is defined as proprietary, and assuming for the moment slightly longer time exposure, the risk of injury is low.
The following factors help to prevent reasonably foreseeable conditions of injury:
- Irradiation unconscious rarely reflect worst-case conditions, such as beam alignment of the pupil, the eye adapting the worst case;
--MPE Inherent safety margin, AEL its basis;
- To avoid bright light of natural behavior.
Compared with 2M, Class 2 in the use of optical instruments does not increase the risk of eye injury.
However, Class 2 laser beam can cause product after dazzling, flash blindness and visual images, especially in low light environments. Temporary visual disturbances or frightened reaction caused by indirect general safety issues. If the user demanding security operations, such as operation of machines, work at height, high voltage work environment or while driving, visual disturbances may need special attention.
Users do not stare into the laser beam to be labeled in accordance with instructions, that by removing the head or eyes closed to complete the active defense reaction and avoid sustained intentional beam eye.
D) 2M category
Definition: in a 400nm ~ 700nm wavelength range, during the work, in the corresponding emission wavelength and duration of human contact up to laser radiation must not exceed Class 2 reach emission limit (AEL) laser products.
Description: This type of laser products emit visible laser beam, only the naked eye safe short-term irradiation. In the following conditions, the use of two optical viewing instruments (eye loupes or binoculars) by irradiation of eye damage can occur:
a) For the divergence of the beam, if the user to focus (collimated) beam and an optical assembly is placed within a distance of 100mm from the light source;
b) For a collimated beam having a diameter larger than the diameter measurement of the third predetermined conditions.
However, 2M laser products after dazzling beam may cause flash blindness and visual images, especially in low light environments. Temporary visual disturbances or frightened reaction caused by indirect general safety issues. If the user demanding security operations, such as operation of machines, work at height, high voltage work environment or while driving, visual disturbances may need special attention.
Users do not stare into the laser beam to be labeled in accordance with instructions, that by removing the head or eyes closed to complete the active defense reaction and avoid sustained intentional beam eye.
E) 3R class
Definition: During the period of work, personnel exposure to laser radiation is allowed to exceed Class 1 and Class 2 up emission limit (AEL), but in any emission duration and wavelength, personnel exposure to laser radiation must not exceed Class 3R and Class 3B each up emission limit (AEL) laser products.
Description: MPE may exceed the radiation-emitting laser products when such apparent in the direct beam, but in most cases is relatively low risk of injury. Because of AEL Class 3R only 2 categories (visible laser beam) AEL or Class 1 (not visible beam) five times the AEL. The risk of damage increases with the irradiation duration and enhanced intentional eye exposure is dangerous. Because of the lower risk, the applicable manufacturing requirements and user controls less than the Class 3B.
Limited risk because:
- Irradiation unconscious rarely reflect worst-case conditions, such as beam alignment of the pupil, the eye adapting the worst case;
--MPE Inherent safety margin;
- Visible radiation under a bright light, and far-infrared radiation on the cornea heated natural avoidance behavior.
After 3R laser products category in the visible range of the laser beam can cause glare, flash blindness and visual images, especially in low light environments. Temporary visual disturbances or frightened reaction caused by indirect general safety issues. If the user demanding security operations, such as manipulation of the machine working in high places, high voltage work environment or while driving, visual disturbances may need special attention.
Class 3R lasers should only occur in the unlikely case of a direct beam depending on use;
F) 3B class
Definition: During the period of work, personnel exposure to laser radiation is allowed to exceed Class 1 and Class 2 up emission limit (AEL), but in any emission duration and wavelength, personnel exposure to laser radiation must not exceed Class 3R and Class 3B each up emission limit (AEL) laser products.
Description: This type of laser beam eye exposure occurs in the product (that is, within NOHD), short-term irradiation include accidental, usually harmful.
Diffuse observe generally safe. AEL of Class 3B close 3B laser can cause minor skin damage, and even the risk of ignition of combustible materials. However, this occurs only to a very small diameter beam or focusing.
Note: There is some theoretical (but rarely) viewing conditions, there may be more than observe diffuse MPE. For example, having a power close AEL of Class 3B laser, observe really diffuse visible radiation, observation time than 10s, between the observation point and diffuse corneal surface at a distance of less than 325px, under the above conditions, will diffuse over MPE.
G) 4 class
Definition: human contact Class 3B laser radiation allowed to exceed the accessible emission limit (AEL) laser products.
Description: This type of laser products, endoscopy and skin irradiation beams are dangerous, watch the diffuse reflection may be dangerous, such lasers are often cause a fire.
Fourth, the spectrum
Fiber laser for laser cutting (wavelength 1.06μm) and CO2 laser (wavelength 10.6μm), are located in IR (infrared) region.

5. the effect of eyedifferent wavelengths of laser 

CO2 laser wavelength of 10.6 μm, belongs to the infrared light is absorbed by the cornea, it can burn the cornea.

CO2 laser will be absorbed by the cornea

Fiber laser wavelength 1.064 μm, belonging to the near-infrared light can pass through the cornea (Cornea) and lens (Lens), and then focused onto the retina (retina) on, and burns the retina.

Fiber laser passes through the cornea and lens focus to the retina

Fiber laser wavelength 1.06 μm, belonging to the near-infrared light can pass through the cornea (Cornea) and lens (Lens), and then focused onto the retina (retina) on, and burns the retina.