Non-Beam / Ancillary Hazards

Laser systems and power supplies may require thousands of volts and tens of amperes to operate. The electrical needs associated with laser use present inherent electrical safety hazards.

These hazards are normally mitigated by the engineering controls (enclosures, interlocks, grounding, etc.) built into the laser systems. However, if these engineering controls are defeated during tuning or maintenance, live contacts can be directly accessed. Contact with these may cause any number of adverse bio-effects, up to and including death by electrocution.

Work on electrical equipment can only be performed by “qualified” personnel (Cal-OSHA requirement). These personnel must be properly trained in electrical safety practices and procedures and must be approved by their department to work on electrical equipment. It is essential that you do not work on electrical equipment if you are unfamiliar with electrical devices or if you are untrained in electrical safety.

Contact your department safety coordinator for specific information on your department’s electrical safety policies and resources. EH&S (510-642-3073) is available to provide electrical safety training and electrical inspection services upon request. For more information on the campus Energy Isolation –Lock-out Tag-out (EL-LOTO) Program and requirement, please visit the EH&S website.

Laser excitation systems and power supplies may produce hazardous collateral radiation of various types. These hazards are normally controlled by the equipment housings and are usually a problem only if the protective housings are removed.

The laser excitation device may produce very intense UV/Visible/IR radiation that can be hazardous. Collateral ultraviolet radiation may injure both the eye and the skin if the exposure duration is long enough. Blue light presents a special hazard because of its ease of absorption in the retina. This “Blue Light Hazard” is thought to create photochemical injury in the retina. Exposure to any very intense visible light source can seriously degrade color vision and night vision capabilities. Exposure to these intense light sources should be carefully controlled or eliminated by leaving the housings in place.

Laser power supplies capable of creating energies greater than 15 kVp may be a source of x-rays if they contain high voltage vacuum tubes. Electric discharge excitation sources in lasers may also be a source of x-rays. Generally, these x-rays are low energy and are shielded by the equipment housings.

Some laser dyes are considered mutagenic and carcinogenic. Halogen gases used in excimer lasers are powerful oxidizers and are toxic if inhaled.

The solvents used for mixing the dyes may be flammable, toxic, or present other health hazards. Material Safety Data Sheets (MSDS) on dyes or solvents are available from your department or by contacting the LSO.

Appropriate PPE (lab coat, disposable gloves, safety glasses or splash goggles, etc.), and a properly functioning chemical fume hood must be used when handling or mixing the dyes.

There is a kinetic energy hazard associated with all compressed gas cylinders. Cryogens can cause burns and eye injuries from contact.

Leaking cylinders may present an asphyxiation hazard if ventilation is insufficient.

The use of compressed gases is common in the laser laboratory. Some lasers use either pure gases or gas mixtures as the lasing media. The high pressure of the gas translates into substantial potential energy stored in the cylinder. If this pressure is released in an uncontrolled manner (such as broken nozzle) the cylinder can become an unguided missile. Compressed gas cylinders must be properly restrained to prevent damage to the nozzle or regulator.

The gases themselves may present a variety of hazards if they leak from the cylinder. Depending on the gas, it may be toxic, corrosive, flammable, etc. Refer to the MSDS for detailed information on the gas in question. If the hazards are sufficient, it may be necessary to provide a gas cabinet under negative pressure to control the hazard in the case of a leak. Inform your department safety contact if compressed gases are to be used in the laser facility.

NOTE: Any gas mixture that falls under the criteria of the campus “Toxic Gas Program” is required to receive pre-approval prior to ordering. For Information on the campus Toxic Gas program, please see the EH&S website.

The interaction of the laser beam with target materials may produce toxic dusts, vapors, or gases. This is particularly true during material processing (welding, cutting, vapor deposition, etc.). Toxic products resulting from laser processing must be properly controlled through the use of adequate ventilation and filtration.

Some laser systems create significant levels of noise in the laser laboratory. If the noise level seems unpleasant or painful, contact your department safety contact to have a noise survey done.

Class 4 lasers can present fire hazards. Lasers being operated in a CW mode with a beam power that exceeds 0.5 Watts can ignite or cause off-gassing in combustible materials left in the beam path. Beam stops, barriers, and curtains used with Class 4 lasers must be made of compatible, non-combustible materials.

Explosion hazards in the laser lab include the storage and use of flammable solvents and gases (both compressed and cryogenic) and the implosion potential from Dewar’s and excitation flash lamps. Proper storage and control of these sources should reduce the potential hazard.