Laser Marking Safety
MECCO has created this brief overview of laser marking safety for your information and safety concerns.
Laser Integration is governed by both Center for Device and Radiological Health (CDRH) and ANSI standard Z136.1 – 2000
• Both specifications main purpose is to warn the operator of the level of laser radiation and protect the operator or persons inside the Nominal Hazard zone from exposure.
• Lasers are rated at different classifications based on the level of exposure.
| CLASS I |
Class I lasers are low powered devices that are considered safe from all potential hazards. Some examples of Class I laser use are: laser printers, CD players, etc. No individual, regardless of exposure conditions to the eyes or skin, would be expected to be injured by a Class I laser. |
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| CLASS II |
Class II lasers are low power (< 1mW), visible light lasers that could possibly cause damage to a person's eyes. Some examples of Class II laser use are: classroom demonstrations, laser pointers, aiming devices and range finding equipment. If class II laser beams are directly viewed for long periods of time (i.e. > 15 minutes) damage to the eyes could result. Avoid looking into a Class II laser beam or pointing a Class II laser beam into another person's eyes. Avoid viewing Class II laser beams with telescopic devices. Realize that the bright light of a Class II laser beam into your eyes will cause a normal reaction to look away or close your eyes. This response is expected to protect you from Class II laser damage to the eyes. |
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| CLASS III |
Class IIIa lasers are continuous wave, intermediate power (1-5 mW) devices. Some examples of Class IIIa laser uses are the same as Class II lasers with the most popular uses being laser pointers and laser scanners. Direct viewing of the Class IIIa laser beam could be hazardous to the eyes. Do not view the Class IIIa laser beam directly. Do not point a Class IIIa laser beam into another person’s eye. Do not view a Class IIIa laser beam with telescopic devices; this amplifies the problem. | |
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| CLASS III B |
Class IIIb lasers are intermediate power (c.w. 5-500 mW or pulsed 10 J/cm²) devices. Some examples of Class IIIb laser uses are spectrometry, stereolithography, and entertainment light shows. Direct viewing of the Class IIIb laser beam is hazardous to the eye and diffuse reflections of the beam can also be hazardous to the eye. Do not view the Class IIIb laser beam directly. Do not view a Class IIIb laser beam with telescopic devices; this amplifies the problem. Whenever occupying a laser controlled area, wear the proper eye protection. |
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| CLASS IV |
Class IV lasers are high power (c.w. >500mW or pulsed >10J/cm²) devices. Some examples of Class IV laser use are surgery, research, drilling, cutting, welding, and micromachining. The direct beam and diffuse reflections from Class IV lasers are hazardous to the eyes and skin. Class IV laser devices can also be a fire hazard depending on the reaction of the target when struck. Much greater controls are required to ensure the safe operation of this class of laser devices. Whenever occupying a laser controlled area, wear the proper eye protection. Most laser eye injuries occur from reflected beams of class IV laser light, so keep all reflective materials away from the beam. Do not place your hand or any other body part into the class IV laser beam. The pain and smell of burned flesh will let you know if this happens. Realize the dangers involved in the use of Class IV lasers and please use common sense. |
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Protective Housing
The protective housing must prevent human access to laser radiation in excess of the limits of Class I at all places and times where and when such human access is not necessary in order for the product to accomplish its intended function.
Safety Interlocks
• Safety interlocks must prevent human access to laser or collateral radiation that exceeds the limits of Class I when a protective housing is opened during operation or maintenance.
• Safety interlocks in Class IV systems must be redundant or fail safe.
•Defeatable interlocks must provide an audible or visible indication of defeat. They must also not allow the cover to close and still be in the defeated position.
Remote Interlock Connector
The purpose of a remote interlock connector is to permit the user to connect a remote barrier interlock, emergency stop switch or similar device. The circuit must be such that, when the terminals of the connector are open, human access to laser radiation is prevented.
Key Control
A key control is required for Class IIIb and IV systems in order for the user to prevent unauthorized operation. The key must not be removable in the "on" position.
Emission Indicator
An emission indicator is required on Class II, IIIa, IIIb and IV laser systems. The indicator can be visible or audible. On Class IIIB and IV laser systems the indication must precede emission by a length of time sufficient to allow users and others in the area to recognize that the product has been energized so they can avoid exposure.
Emission indicators must be duplicated on lasers (heads) and operation controls if they are capable of being separated by greater than 2 meters.
Safety Shutter
A beam attenuator (shutter) is required on Class II, IIIa, IIIb and IV laser systems. The beam attenuator is a mechanical or electrical device such as a shutter or attenuator that blocks emission. The beam attenuator blocks bodily access to laser radiation above Class I limits without the need to turn off the laser. The beam attenuator must be available for use at all times during operation.
Operating Controls
Operating controls on a Class II, IIIa, IIIb or IV laser product must be located such that it is not necessary for the user to be exposed while manipulating them.
Manual Resets
A manual reset is required on Class IV laser systems. It must prevent automatic restart after an interruption due to remote interlock activation or from an interruption for more than 5 seconds due to unexpected loss of main power.
Safety Labeling
• A warning logotype is required for Class II, IIIa, IIIb and IV laser products.
• Removable or displaceable protective housings that are not safety locked or that have defeatable safety interlocks also require warning labels. Labeling must be visible on the product prior to and during removal or displacement of the housing and close to the opening involved.
•An aperture warning label is required for each aperture through which laser radiation in excess of Class I or IIa.
•A certification label is required and must state that the manufacturer certifies that the product complies with the standard or with an approved variance.
•An identification label must be provided and must contain the name and address of the manufacturer and the place, month and year of manufacture; the month and year of manufacture may not be abbreviated.
Nominal Hazard Zone
The nominal hazard zone (NHZ) describes the space within which the level of direct, reflected, or scattered radiation during normal operation exceeds the appropriate MPE's and is determined from the following characteristics of the laser:
–Power or energy output.
–Beam diameter.
–Beam divergence.
–Pulse repetition frequency (prf).
–Wavelength.
–Beam path including reflections.
–Beam profile.
–Maximum anticipated exposure duration
MAXIMUM PERMISSIBLE EXPOSURE (MPE)
The level of laser radiation to which person may be exposed without hazardous effect or adverse biological changes in the eye or skin.
Protective Housing:
• “Light Tight”: No direct exposure from laser light. Laser must take more than 1 bounce orreflection to harm operator
•Overlapping of panels on any access point
•Safety Interlocks (2x) on doors or access panels to the laser enclosure/zone
•Viewing windows are available in both glass and plastics. Substrates are coated for specific wavelength of laser.
•Emission and shutter indicators.
•Must file Class 1 enclosure with CDRH
