Associated Laser System Hazards
Besides the risks from the laser energy, some laser installations may contain hazards
from ancillary equipment used in the process. The following are potential associated
laser system hazards.
• Electrical hazards. Most laser systems pose a potential for electrical shock (e.g., capacitor banks in pulse lasers, high-voltage DC or RF power supplies in CW lasers, etc.). While not usually present during laser operation, they are a risk during installation and maintenance. Insure high voltages are not exposed and capacitors are properly discharged. Water used as a cooling system on some lasers may increase the shock hazard.
• Chemical hazards. When a laser interacts with any material, energy is tramsmitted resulting in vibrational energy (heat). If the irradiance is high enough, molecular bonds are disrupted and small particles of the processed material are vaporized and separated. As they cool, they recondense forming fine solid particulate substances. Table 7.1 lists some Laser Generated Air Contaminants (LGAC) which may pose a hazard. Adequate ventilation is needed to control vaporized target materials; gasses from flowing gas lasers or laser reaction byproducts (e.g., bromine, chlorine, hydrogen cyanide, ozone, etc.); gases or vapors from cryogenic coolants; and vaporized biological target materials (from medical applications). Many dyes used as lasing media are toxic, carcinogenic, corrosive or pose a fire hazard. An MSDS should be available for any chemical handled in the laser laboratory. Cryogenic coolants (e.g., liquid nitrogen, helium, and oxygen) may cause skin and eye injury if misused.
• Collateral radiation hazards. Collateral radiation is radiation other than that associated with the primary laser beam. These include X-rays, UV, plasma and RF. Any power supply which requires more than 15 kV may be a source of x-rays.
• UV and visible radiation hazards. Laser discharge tubes and pumping lamps may generate UV and visible radiation at levels exceeding safe limits for the eye and skin. Flash lamps and CW laser discharge tubes may emit direct or reflected UV radiation which could be a potential hazard if quartz tubing is used.
• Fire hazards. Class IV lasers may cause fires in materials found in beam enclosures, barriers, stops and electrical wiring if they are exposed to high beam irradiance for more than a few seconds.
• Explosion hazards. High-pressure arc lamps, filament lamps, and capacitors may explode if they fail during operation. These should be enclosed in protective housings. Laser targets and some optical components may shatter if heat can not be dissipated quickly enough. Use adequate shielding when brittle material must be exposed to high intensity lasers. Radiation producing machines are regulated by Federal and State agencies. The Food and Drug Administration (FDA) regulates manufacturers of electronic systems capable of producing laser and high intensity light. The goal is to insure that manufactured systems are safe. However, it is possible that a laser lab may make changes either to the laser configuration or to the lasers use creating a potentially unsafe work place.
Table 7.1: Common Laser Generated Air Contaminants (LGAC)
|| magnesium, silicon, chromium, nickel
|| chromium, nickel, other base metals
|| benzene, acrolein, alkenes, alcohols
|| benzene, PAHs, carbon oxide
|| formaldehyde, benzene, styrene, hydrogen cyanide
||formaldehyde, hydrogen cyanide, methanol, furfural, furan, cyanomethal, acetate
||formaldehyde, methyl butadiene, methyl acrylate, limonene, methanol, phthalic acid, ester
||bacteria, viral strains, organic compounds, formaldehyde, benzene, hydrogen cyanide
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