SU's Laser Program
Syracuse University’s Laser Safety Program provides guidelines for ensuring compliance with applicable regulations and standards of care. The program is established in compliance with New York State Department of Labor’s Laser Regulations, 12 NYCRR Part 50, and also contains many of the guidelines recommended by the American National Standards Institute’s American National Standard for the Safe Use of Lasers (ANSI Z136.1). All activities involving lasers at Syracuse University must be conducted in compliance with applicable regulations and in a manner that protects University personnel, students, visitors and property from harmful exposures to laser radiation.
This Program specifically applies to operations involving class 3b and 4 lasers. Operators of class 1, 2 and 3a lasers should follow manufacturer’s guidance and appropriate safety recommendations.
Laser Safety Program Components
Laser Safety Responsibilities
The University’s Laser Safety Program requires coordinated cooperation among various groups and individuals within the University Community. The Director of the University’s Environmental Health Office (EHO) will serve as the University’s Laser Safety Officer (LSO). The LSO is responsible for implementation and oversight of the University’s Laser Safety program. The LSO will provide guidance to Laser Supervisors and operators to ensure that all lasers use on campus is conducted in a safe manner in an accordance with all applicable rules and regulations. The Environmental Health Office is responsible for maintaining a comprehensive inventory of class 3b and 4 lasers at the University. EHO will also investigate laser related incidents and specify appropriate corrective actions as necessary. EHO may also periodically conduct audits of laser areas to verify compliance with regulatory and program requirements.
Laser Supervisors
A Laser Supervisor is a permanent University employee, generally the laboratory’s principle investigator, responsible for the overall operation of lasers in the laboratory. The Laser Supervisor must be knowledgeable of the potential laser hazards, necessary operation and control measures, and the requirements of the University’s Laser Safety Program. Each laser owned maintained or operated at the University is required to have a Laser Supervisor. The responsibilities of a Laser Supervisor include but are not limited to:
1. Maintaining a safe working environment in which to conduct laser activities and directly implementing the University’s Laser Safety program for the laser(s) under their supervision.
2. Registering each laser under their supervision with the Environmental Health Office (EHO) and informing EHO prior to the purchase, disposal, modification or relocation of any laser under their supervision.
3. Developing and implementing laser operating procedures for their laboratory and assuring that all required laser related administrative, engineering and environmental control measures are in place and followed for the laser(s) under their supervision.
4. Being familiar with program requirements and the specific standard operating procedures for their laser(s) and ensuring that these procedures are available to all operators of class 3b and 4 laser operators under their supervision.
5. Providing for the proper control of the laser(s) operated under their supervision to virtually eliminate the potential of injury to personnel, including transient and uninformed individuals.
6. Providing appropriate protective eye wear, as necessary and inspecting each piece of protective eye wear ever six months (see Protective Equipment)
7. Ensuring that necessary warning labels and signs, interlocks, personal protective equipment, etc. Is available and used appropriately in their laser use areas.
8. Providing laser specific instruction on proper operation and hazard control to personnel using the laser(s) under their supervision or permitted to frequent their Laser Area and ensuring that these individuals are knowledgeable in the requirements of the Laser Safety program.
9. Reporting to EHO, known or suspected accidents resulting from or involving lasers under their supervision and taking all necessary corrective actions to prevent reoccurrence.
10. Safeguarding their laser(s) against unauthorized use.
Laser Operators
Only individuals authorized by the laser’s Laser Supervisor and knowledgeable of the operation and hazards associated with lasers may energize or operate a Class 3b or 4 laser. The responsibilities of Class 3b and 4 Laser Operators include, but are not limited to:
1. Observing safety rules, using prescribed protective equipment and controls, and following practices and procedures established for safe laser operation.
2. Being familiar with the operating requirements and specific safety hazards of the laser(s) which they are authorized to operate.
3. Notifying their supervisor of conditions or practices that have the potential of causing personal injury or property damage.
4. Immediately informing their supervisor or EHO of all known or suspected laser incidents, accidents, injuries or exposures involving himself/herself or another individual(s).
5. Ensuring that all spectators are properly informed of and protected from potential laser hazards.
6. Ensuring that they receive specific instruction on proper laser operation and hazard control and that they are knowledgeable in the requirements of the Laser Safety Program.
7. Following the standard operating procedures for the laser(s) which they are authorized to use.
Laser Classification
The laser classification scheme used at Syracuse University is based on the ANSI Laser Standard, Z136.1-1993. Lasers are classified into four hazard classes based their potential to cause biological damage under normal operating conditions. The parameters used for laser classification are: 1) average output energy or power, 2) wavelength(s) or wavelength range, 3) exposure or pulse duration, and 4) emergent beam radiant exposure.
The Bureau of Radiological Health requires that lasers manufactured after August 1, 1976 be labeled, by the manufacturer, with a warning notice which specifies the laser’s hazard class. This assigned hazard class applies to lasers intended for “normal use”. Lasers that are modified in any way may no longer conform to the requirements for their assigned hazard class. The LSO will assist in assigning a hazard classification to any unclassified laser manufactured prior to 1976.
Class 1 - Exempt Lasers
Lasers that are incapable of producing biological damage during normal operating conditions are classified as Class 1 lasers. Class 1 lasers can not emit accessible laser radiation in excess of the Class 1 Accessible Emission Limit (AEL) for any combination of emission duration and wavelength range. Most lasers in this class are there by virtue of an enclosure that prohibits or limits access to the laser radiation (i.e. a higher class laser imbedded into an enclosure which prohibits access to the laser is classified as a class 1). A laser printer is an example of a class 1.
Class 2 - Low Power Visible Lasers
Class 2 lasers include only those lasers emitting in the visible wavelength (400-700 nm) region. Class 2 continuous wave lasers must have a radiant power level of less than 1mW and Class 2 repetitively pulsed lasers may not exceed the Class 1 AEL with an "aversion response time" exposure duration (<0.25 seconds). Class 2 visible light lasers are capable of causing retinal injury only if viewed directly for an extended period of time. However, since retinal injury can potentially occur, Class 2 lasers should have a caution label warning the operators not to stare into the beam. Examples a class 2 lasers include some laser pointers and some continuous wave HeNe lasers.
- Class 2a Lasers: Specific use, visible light laser systems that do not exceed than the Class 1 AEL and are not intended for viewing are designated as Class 2a lasers. Class 2a lasers are considered to be a lesser hazard than the Class 2 lasers. Class 2a lasers may cause retinal injury if directly viewed for more than 1000 seconds. Examples of Class 2a lasers include some bar code readers.
Class 3 - Medium Power Lasers
Class 3 lasers are dived into two subclasses, 3a and 3b, with Class 3a being a lower hazard classification than 3b. In general, Class 3 lasers are hazardous only under direct beam and specular reflection viewing conditions.
- Class 3a Lasers: Laser systems with power levels of 1 mW to 5 mW are classified as Class 3a lasers. Class 3a lasers are potentially hazardous if the output is collected and focused into the eye or onto the skin. These lasers are not likely to cause injury when viewed for momentary periods with the unaided eye, but may cause injury when directly viewed with optical instruments (i.e. binoculars, collecting optics).
- Class 3b Lasers: Lasers with accessible output power greater than the Class 1 AEL but less than 500 mW which do not meet the Class 3a qualifications are classified as Class 3b Lasers. Class 3b lasers are acute eye hazards. They can produce accidental injury to the retina from both direct viewing and specular reflection.
Class 4 - High Power Lasers
Class 4 is the highest laser hazard classification. This classification includes continuous wave lasers with accessible output emissions greater than 500 mW or a radiant power of greater than 150 mJ per pulse for visible or near IR wavelengths or 125 mJ per pulse for all other wavelengths. Class 4 lasers are capable of causing severe eye damage with short duration (less than 0.25 s) exposures to the direct, specularly reflected and/or diffusely reflected beam. These lasers may also cause severe skin damage and may be capable of igniting flammable and combustible materials.
Laser Hazards
Hazards associated with lasers can be categorized into two categories: beam and non-beam. The most obvious hazards are those associated with the beam itself; however, non-beam or accessory hazards are just as important and deserve the same amount of safety concern.
Beam Hazards
Hazards directly associated with the laser beam itself include both eye and skin injuries. The occurrence of beam related injuries can be greatly reduce through strict adherence to proper safety practices and procedures.
- Eye Injury: A laser beam is capable of inflicting serious biological to the unprotected eye. Biological effects in the eye may occur from both acute and chronic eye exposures. The structure of the eye that is effected by the laser exposure and the extent of damage produced is dependent on the wavelength of the laser beam and the amount of energy absorbed by the eye structure.
- Skin Injury: Acute and chronic exposure to lasers may result in serious skin damage. Biological effects to the skin associated with laser exposures are dependent on the wavelength and power of the laser radiation. Since the radiant exposure must be relatively high to cause skin damage, Class 1, 2 and 3 lasers generally do not present a skin hazard. However, acute exposure to high-powered lasers (class 3b and 4) can result in a photosensitive reaction, erythema and skin burns. Chronic skin exposures to laser radiation may also accelerate aging and cause skin cancer.
Non-Beam Hazards
- Electrical: Electrical hazards are the primary non-beam hazard associated with lasers. The electrical power supplies of lasers and laser systems, especially those of Class 4, can result in electrocutions and electrical shocks. All lasers used at the University, including their associated electrical equipment, must be designed, constructed and installed in manner that minimizes the possibility of electrical hazards. Only specifically trained individuals may repair and troubleshoot laser systems.
- Hazardous Materials: Materials (i.e. lasing media) used in laser operations and airborne byproducts produced from laser interactions can be potentially hazardous to the laser operator and other individuals in the area. Some of the dyes, chemicals and gases used as laser medium are toxic and/or reactive. A Materials Safety Data Sheet (MSDS) must be available in the workplace for each hazardous lasing dye or associated chemical used or stored. The MSDS must be reviewed by the laser operator prior to use of a hazardous material to ensure all necessary safety measures and protective equipment are employed. Laser interactions with target materials may also result in the release of toxic gases and heavy metals. Control of these hazards must be employed through use of engineering controls or personal protective equipment as necessary.
- Fire and Explosion: Class 4 lasers are capable of igniting combustible and flammable materials. To minimize the fire potential, special care should be taken to ensure that Class 4 lasers do not directly interact with combustible or flammable materials. In addition, mixing incompatible lasing media may create an explosion potential. Care must be taken to avoid mixing any incompatible materials. Applying a voltage in excess of the potential of the capacitors in the laser power supply may also produce an explosion potential.
- Ionizing Radiation: X-ray radiation can be produced by the high voltage power supply of the laser. However, this radiation is generally shielded by the vacuum tube itself.
- Reflected Beam Hazards: Specturaly reflected beams from Class 3b and 4 lasers and diffusely reflected beams from Class 4 lasers present a hazard. Steps must be taken to prevent accidental exposures from stray (reflected) beams including the use of non-reflective instrumentation, enclosures for beam-mirror interaction sites and beam stops.
Control Measures
Control measures for Class 3b and 4 laser operations must be designed to prevent potential eye or skin injury from the laser radiation and injury from other hazards associated with the laser operation. Maximum Permissible Exposure (MPE) is the level of laser radiation to which an individual can be exposed without hazardous effect or adverse biological changes to the eye or skin. The MPE is determined based on the specific parameters of the laser including wavelength, output power or energy and exposure duration. The MPE for a laser may change if any of these parameters are modified. Controls measures must be employed to ensure that the skin or cornea of any individual in the laser use area is not exposed to laser radiation in excess of the MPE.
Engineering and Environmental Controls
Engineering and environmental controls are typical methods of controlling potential laser exposures by directly modifying the laser system and/or the laser use area. Some of these controls may be design directly into the laser system by the manufacturer and other types may need to be devised and/or adopted by laser operators to aid in ensuring a safe working environment.
- Beam Stops: Non-reflective and fire retardant beam stops must be used wherever necessary to prevent stray beams. If the primary beam of a class 3b or 4 laser is not enclosed it must be terminated at the end of its useful path.
- Beam Enclosures: The entire path of Class 3b and 4 lasers should be surrounded by an enclosure. This enclosure should be equipped with interlocks that prevent operation of the laser if the enclosure is not properly secured. Interlocks must not be used to actuate the laser.
- Key Switch Access: Class 3b and 4 lasers manufactured in the USA are generally equipped with a key switch or a computer password security mechanism. These security features are designed to prevent unauthorized access to or operation of a laser. If a key switch is present, the key switch should be disable and the key should be removed from the system when it is not in use. Access to the key must be vested in authorized personnel only. If a password security control is provided for a computer driven laser, the password must only be provided to the authorized laser operators and must not be posted on or around the laser system.
- Non-Reflective Surfaces: The surfaces of laser use areas must be non-reflective and all shiny objects that may cause unwanted and potentially hazardous beam reflections must be eliminated from the laser beam paths.
- Protective Barriers/Curtains: Protective barriers and/or curtains must be used to close off and contain the Class 3b and 4 Laser Use Areas. The protective barriers must be non-flammable, non-reflective and sufficient to reduce the exposure below the MPE.
- Covered Windows: Windows in a Class 3b and 4 laser use area(s) should be covered with a protective filter or shielded with a protective barrier during laser operation. If the window is in an exterior (hallway) door the window can’t be covered. In this case a barrier should be used which shields the window from the laser but doesn’t prevent egress.
- Warning Lights: Warning lights in addition to the required posting and labeling should be used as an extra method of warning of a Class 3b and 4 laser in operation.
- Positioning of the Laser Set-up: Laser beams must not be operated at eye level. During operation, the laser and associated equipment, lenses, etc. must be secured to a table at a height other than eye level.
Administrative Controls
Administrative controls are methods of controlling potential laser exposure through policies and procedures. Additional or more restrictive controls may be necessary for certain lasers or laser use areas due to the nature of the potential hazard.
- Security: Class 3b and 4 lasers must not be left unattended during operation unless the area is secured from unauthorized entry. In addition, entry points (i.e. doors) to Class 3b and 4 Laser Use Areas should be restricted to authorized personnel only. Where such restriction is not feasible, alternative mechanisms (i.e. warning alarm, laser on light, etc.) should be used to adequately warn individuals entering the area of the laser hazard present. Precautions should also be taken to prevent unauthorized use of and/or exposure to medium (3a) and low power lasers.
- Controlled Laser Use Area: Class 3b and 4 lasers must only be operated in controlled areas designated for laser operations. The controlled Laser Use Area should be a separate room/laboratory or an area within a larger room sectioned off with barriers that block the laser radiation. Access to the Laser Use Area must be restricted to authorized personnel only. Restricted access can be achieved by virtue of a locked door, interlocks which shut off the laser when the door to the area is opened or any other means which controls access to the area for the purpose of protecting individuals from exposure to laser radiation. Spectators and non-authorized individuals may only access a controlled Laser Use Area when accompanied by an authorized laser operator.
- Standard Operating Procedures: Standard operating procedures for use of each Class 3b and 4 laser should be written and accessible to laser operators. These procedures should include steps necessary for assurance of safe operation (i.e. donning of protective equipment). If such procedures are contained in a laser’s operation manual(s), a separate procedure detailing safety precautions and steps that need to be taken should be posted in the Laser Use Area.
- Emergency Shut-Off Procedure: An emergency shut- off procedure for each Class 3b and 4 laser should be written and posted near the laser. An emergency shut off switch is recommended for Class 3b and 4 lasers for use in the case of an emergency.
- Alignment Procedures: Caution must be taken when performing alignment procedures. They must be performed in a manner that ensures eye exposures do not exceed to MPE.
Personal Protective Equipment
Engineering and administrative controls must be used whenever possible to keep laser exposures below the MPE. When these controls are not feasible or not sufficient enough to reduce exposures below the MPE, appropriate protective equipment must used to protect an individual’s skin and eyes from potential injury.
Eye Protection
The best way to avoid an eye injury from a laser is to not look directly into the laser beam or its specular reflections. Added protection for use with high-powered lasers can be achieved through the use of protective eyewear. NYSDOL regulations require protective eyewear be worn by an individual if there is a potential for that individual to exceed the Maximum Permissible Exposure (MPE) when viewing the beam. In compliance with this, the University requires that individuals wear protective eyewear when viewing the beam(s) of any class 4 laser and when viewing the beam(s) of a class 3b laser if there is a potential for the individual to exceed the MPE or if the MPE unknown or unavailable.
- Selection: No one type of eyewear offers protection from all laser wavelengths. Appropriate protective eyewear must be selected based on the wavelength and energy/power of the laser to be used. Appropriately selected eyewear must sufficiently reduce the potential exposure from laser radiation below the MPE and must be able to withstand a direct beam exposure for 10 seconds without failing. It is the responsibility of the Laser Supervisor to ensure appropriate eye protection is provided, as necessary, at no cost to the laser operator. Each piece of protective eyewear must be legibly labeled with the lens' optical density and the wavelength at which it was measured.
- Inspection: The Laser Supervisor is also responsible for inspecting each piece of protective eyewear at least every six months to ensure the optical density and type of filter is appropriate for the laser in use and to determine visually that the eyewear has no optical defects. The eyewear inspection must be recorded and available for review. If damage is suspected the eyewear must immediately be withdrawn from use and repaired if possible or otherwise discarded and replaced.
Skin protection
Appropriate skin protection must be used if there is a potential for an individual to receive a skin exposure from laser radiation in excess of the MPE. Skin protection is also recommended for chronic/extended exposure to ultraviolet (UV) radiation. In cases where protective clothing is warranted, the clothing must be appropriate for the type and power of the laser and manufactured of non-flammable material. It is the responsibility of the Laser Supervisor to provide the necessary skin protection at no cost to the individual.
Other Protective Equipment
Many dyes, chemical and gases used as laser media are hazardous and require additional considerations for personal protection (i.e. respirators and gloves). EHO should be contacted for assistance in determining the need for and selection of appropriate skin or respiratory protective equipment. It is the responsibility of the Laser Supervisor to provide the necessary protective equipment at no cost to the individual.
Signs and Labeling
The following is the universally accepted laser radiation symbol.
The color of this symbol must be red and the background color must be yellow or white.
NYS Department of Labor regulations require that the laser symbol be used to designate lasers and Laser Radiation Areas.
Posting Laser Use Areas
The entrance to all Class 3b and 4 Laser Use Areas must be posted with the laser symbol and the words “Danger” or Caution” and “Laser Radiation Area” in black lettering. The posting must be legible and placed conspicuously to warn all persons entering the area of the potential laser hazard. It is the responsibility of the Laser Supervisor to ensure proper laser use area posting.
Labeling Laser Equipment
It is the responsibility the Laser Supervisor to ensure the laser(s) under their supervision are labeled appropriately and in compliance with NYS DOL regulations (12 NYCRR Part 50.15). All Class 3b and 4 lasers (or their laser housings) must be marked with the laser symbol in red and the words “Danger” or “Caution” and “Laser” in black letter. These lasers must also be labeled with:
- maximum output power or energy density energy(s)
- lasing material (as applicable)
- wavelength(s) of emitted laser radiation.
- Divergence of the emitted laser radiation in its lowest order transverse mode.
The labeling must be legibly stamped, etched or otherwise permanently marked on a yellow or white label. If such labeling is impractical because of the size of the laser, the laser must be appropriately labeled in an alternative manner (i.e. labeling the use area or storage container, etc.). Lasers used exclusively in research and development do not need to specify the wavelength, output power/energy where such parameters are unknown or unobtainable.
All Class 2 and 3a lasers should, at a minimum, be labeled with the laser symbol, the words “Caution Laser” and the hazard classification. Class 2 lasers should also be labeled to warn individuals not to stare directly into the beam.
Equipment Maintenance
The service, repair and/or modification of any Class 3b and 4 laser ( or embedded Class 3b and 4 laser) on campus must only be performed by trained service personnel. Service personnel must comply with all appropriate safety procedures and must have sufficient safety training and experience for the laser being serviced. Modifications or service to lasers that may affect the output power or its inherent safety features must be reported to the Laser Safety Officer. The LSO will assess the modifications and determine in additional safety measures are required.
Laser Incidents
The LSO must be notified immediately of any laser related incident involving properly damage, misuse, personal injury or the potential for personal injury. Such incidents include, but are not limited to, eye injury, skin burns, exposure to toxic laser dyes and chemicals, and fires. Personal injuries resulting from lasers will be referred to the Student Health Center.
The LSO will review all reported laser incidents and associated exposures and notify NYSDOL as necessary. The LSO will write a report detailing the incident and recommending steps that should be taken to prevent a reoccurrence. The incident report will be maintained on file at the Environmental Health Office. A copy of the report will also be sent to the affected Laser Supervisor.
Laser Safety Instruction and Training
All individuals frequenting a Class 3b and 4 Laser Area must be instructed on the hazards associated with the use of lasers, precautions and procedures necessary to minimize exposure, and the requirements of NYSDOL regulations and the University's Laser Safety Program. It is the responsibility of the Laser Supervisor to provide these individuals with the necessary instruction and to document such instruction. The Environmental Health Office is available to assist Laser Supervisors in ensuring that appropriate instruction is provided.
Laser Inventory and Tracking
In Compliance with NYSDOL regulations, institutions possessing Class 3b and 4 lasers must maintain an inventory of such lasers and update the inventory at least annually. The Environmental Health Office (EHO) has established a laser inventory database to record and track all lasers, particularly Class 3b and 4, used, maintained and/or stored on University owned or operated property. The database includes the type, classification, supervisor and storage location of each laser and any other relevant information available (i.e. power output, manufacturer, serial number, etc.).
EHO performs an annual review of the University’s laser inventory. To aid in ensuring the accuracy of the inventory, Laser Supervisors must register each laser under their supervision with EHO. EHO must also be notified prior to the purchase, relocation or disposal of any laser on University property.
Laser Purchase
EHO must be notified prior to the purchase of any Class 3b or 4 laser or laser system. It is the responsibility of the Laser Supervisor to notify EHO of the proposed purchase. EHO will review proposed laser purchases to assure regulatory compliance and to determine if all necessary safety features and controls will be provided or if any special use area accommodations are warranted.
Laser Sale/Disposal
EHO must be notified prior to the disposal sale or transfer of any Class 3b or 4 laser. If the laser is to be disposed, it must be made permanently inoperable prior to disposal. If the laser is to be sold/transferred to another institution, the receiving institution must obtain any registration/permit necessary for compliance with NYSDOL or any regulatory agency under which the institution’s laser use is governed.
Lasers Pointers
Lasers pointers must bear a “caution” or “danger” warning label. These labels must not be defaced or removed. Laser pointers must be used properly to avoid eye injury. Class 2 laser pointers can produce injury if an individual suppresses their blink reflex and stares directly into the laser beam. Class 3a laser pointers have a higher output power and therefore can be hazardous if viewed directly for even a brief period of time. A reflected beam off a mirror-like (i.e. shiny metal) surface can act like a direct beam on the eye. However, diffuse reflections (i.e. off a projection screen) from laser pointers present no eye hazard.
Care should be taken when using laser pointers in teaching and demonstration. Never directly point the laser at an individual. Never stare directly into the laser beam. In addition, when feasible, disable the power supply to the laser (i.e. remove the battery) when storing lasers to prevent accidentally activation.
Accessible Emission Limit
AEL-21CFR1040.10
Maximum Permissible Exposures
|
TABLE 1
MAXIMUM PERMISSIBLE CORNEAL EXPOSURE FOR DIRECT ILLUMINATION OR SPECULAR
REFLECTION OF LASER RADIATION (*) |
|
Q-switched 1 nanosecond to 1
microsecond pulse
[10-9- 10-6 sec.]
(joules/cm2) |
Non-Q-switched 1 microsecond to
0.1
of a second pulse [10-6- 10-1sec.]
(joules/cm2) |
Continuous wave or pulse width
greater than 0.1 of a second duration
[Greater than 10-1 sec.](watts/cm2) |
|
|
|
1.0 X 10-7(**) |
1.0 X 10-6 **
|
1.0 X 10-5 * *
|
|
1.0 X 10-3 (***)
|
1.0 X 10-2 ***
|
1.0 X 10-2 ***
|
|
|
(*)The values in this table assume
a diffraction limited and zero order transverse mode beam. In the case of a
higher order transverse mode in a gas laser where the intrinsic beam divergence
exceeds one milliradian the values may be increased on the basis of experimental
evidence. Because of the lack of data, no explicit value is listed for the
maximum permissible corneal exposure for laser radiation in the wave length
range below 400 nm. or for sub-nanosecond pulses; therefore the cornea shall not
be directly exposed to this radiation until MPCE values have been established
for these conditions.
(**)For lasers operating in the wave length range 400-1400 nm.
(***)For lasers operating in the wave length range above 1400nn.
|
TABLE 2
MAXIMUM PERMISSIBLE SKIN EXPOSURE (*)
|
|
|
|
Energy Density Pulsed
[Q-switched, Non=Q-switched]
(joules) |
Pulsed Power Density,
Continuous Wave
(watts) |
|
(cm2) |
(cm2) |
|
|
|
0.1 |
1.0 |
|
|
(*)For lasers operating in the visible, near-infrared and infrared regions of
the electromagnetic spectrum. No information is available on permissible skin
exposures to laser radiation in the wave length range below 400 nm. Therefore,
caution must be used to avoid such exposure until experimental data is available
on permissible levels.
