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Definition and Properties of Laser Light

How a Laser Works

Laser Types and Classifications

Laser Biological Hazards

Eyes

Skin

Non-Beam Laser Hazards

Protective Measures - Laser Safety

Protective Equipment

Path to Laser Operation

Test

Laser Links

Non-Beam Hazards

As shown previously, an exposure to laser light can be hazardous to both the eye and skin. There are other hazards related to the operation of a laser besides exposure to the beam or its reflection. Many of these non-beam-related hazards can be far more dangerous than the beam itself. This section will discuss these "non-beam hazards".

Electrical Hazard

With the use of large power supplies and repetitively pulsed lasers, there is a great potential for electric shock. Shocks usually happen when a person is working on equipment that is not properly grounded or has a large capacitor bank that was not discharged. Most injuries to personnel involving lasers are of this type. For this reason, the "buddy" system should always be observed when performing maintenance on high voltage equipment. According to the ANSI Z136.1, the following potential problems have frequently been identified during laser facility audits:

Uncovered electrical terminals.

Improperly insulated electrical terminals.

Hidden "power up" warning lights.

Lack of training in current cardiopulmonary resuscitation practices, or lack of refresher training.

"Buddy system" not being practiced during maintenance and service.

Non-earth-grounded or improperly grounded laser equipment.

Non-adherence to the OSHA lock-out standard (29CFR1910.147).

Excessive wires and cables on floor that create fall or slip hazards

Explosion Hazard

With the use of high-pressure arc lamps, filament lamps, and capacitor banks in laser equipment, there is a potential for explosion hazards. These items should be enclosed in housings that can withstand the high pressure resulting from exploding components.

Compressed Gasses

Many lasers are used that incorporate hazardous gases such as chlorine, fluorine, hydrogen chloride, and hydrogen fluoride. Referring again to ANSI Z136.1, there are typical safety problems that arise in the use of compressed gasses. These include:

	Working with free-standing cylinders that are not isolated from personnel.
	Inability to protect open cylinders (regulator disconnected) from atmosphere and contaminants.
	No remote shutoff valve or provisions for purging gas before disconnect or reconnect.
	Labeled hazardous gas cylinders not maintained in appropriate exhausted enclosures.
	Gases of different categories (toxics, corrosives, flammable, oxidizers, inerts, high pressure, and cryogenics) not stored separately in accordance with OSHA and Compressed Gas Association requirements.

Laser Dyes and Solvents

Dyes are used in some lasers as a lasing medium. These dyes are complex organic compounds that are mixed in solution with certain solvents. Some dyes are highly toxic or carcinogenic, and great care must be taken when handling them, preparing solutions, and operating lasers that contain these dyes. A Material Safety Data Sheet must be made available to anyone working with these dyes.

Noise

Some lasers, such as the Excimer, create an intensity of noise that may require controls to be instituted. The Health and Safety Office should be consulted if there are concerns about noise.

Fire Hazards

There is a great potential for a fire hazard to exist with the use of Class IV lasers. Fires can occur when a Class IV laser is enclosed in a material that is exposed to irradiances greater than 10 W/cm2 or beam powers exceeding 0.5 W. Fire resistant materials should be used in this situation.

Barriers such as black photographic cloth are used in a wide variety of applications for the purpose of containing the beam. These materials should not be used as the primary barrier for a high-powered Class IV system. Beams of sufficient energy will burn this material quickly, causing smoke, fire, and breach of the barrier. The use of beam blocks and beam stops is highly encouraged in this situation.

Non-Beam Hazards

Electrical Hazard

Uncovered electrical terminals.

Improperly insulated electrical terminals.

Hidden "power up" warning lights.

Lack of training in current cardiopulmonary resuscitation practices, or lack of refresher training.

"Buddy system" not being practiced during maintenance and service.

Non-earth-grounded or improperly grounded laser equipment.

Non-adherence to the OSHA lock-out standard (29CFR1910.147).

Excessive wires and cables on floor that create fall or slip hazards

Explosion Hazard

With the use of high-pressure arc lamps, filament lamps, and capacitor banks in laser equipment, there is a potential for explosion hazards. These items should be enclosed in housings that can withstand the high pressure resulting from exploding components.

Compressed Gasses

Many lasers are used that incorporate hazardous gases such as chlorine, fluorine, hydrogen chloride, and hydrogen fluoride. Referring again to ANSI Z136.1, there are typical safety problems that arise in the use of compressed gasses. These include:

Working with free-standing cylinders that are not isolated from personnel.

Inability to protect open cylinders (regulator disconnected) from atmosphere and contaminants.

No remote shutoff valve or provisions for purging gas before disconnect or reconnect.

Labeled hazardous gas cylinders not maintained in appropriate exhausted enclosures.

Gases of different categories (toxics, corrosives, flammable, oxidizers, inerts, high pressure, and cryogenics) not stored separately in accordance with OSHA and Compressed Gas Association requirements.

Laser Dyes and Solvents

Noise

Some lasers, such as the Excimer, create an intensity of noise that may require controls to be instituted. The Health and Safety Office should be consulted if there are concerns about noise.

Fire Hazards

There is a great potential for a fire hazard to exist with the use of Class IV lasers. Fires can occur when a Class IV laser is enclosed in a material that is exposed to irradiances greater than 10 W/cm2 or beam powers exceeding 0.5 W. Fire resistant materials should be used in this situation.

X-Ray Radiation Hazards

X-rays may be generated by electronic components of the laser system(e.g., high-voltage vacuum tubes and from laser-metal induced plasmas).

Radio-Frequency Radiation Hazards

Some lasers contain RF excited components, such as plasma tubes and Q-switches.

Mechanical Hazards Associated with Robotics

Limited Work Space Dangers

Erogonomic Considerations