Lifetime. As mentioned above, lifetimes of laser dye solutions are limited and depend on the dye and operating conditions. Progress has been made in extending dye lifetime, but high pump energy and short pump wavelength do cause dyes to degenerate faster.

Flashlamps also have limited lifetimes, which differ considerably among different types. Lifetime decreases very rapidly as pulse energy increases. For example, a 500-J coaxial flashlamp will last only 10,000 to 20,000 shots if operated at 500 J, but if energy loading is decreased to 64 percent of that value, lifetime will exceed 750,000 shots (Furumoto, 1986). Linear flashlamps can produce millions of shots. Sometimes lifetimes are given in terms of total energy that a lamp can deliver before failure, typically in the range of 10 ⁷ to 10 ⁸ J. Lamp failures occur when output energy decreases below a required level, but lamps driven too hard can explode.

Except for dyes and flashlamps, lifetime figures generally are not given for dye lasers.

Maintenance and Adjustments Needed. Several types of maintenance may be needed for dye lasers. These include

• Periodic replacement of dye solutions or replenishment of dye.

• Replenishment of volatile components of dye solution lost by evaporation.

• Cleaning the dye system when switching dyes to avoid optical losses from impurities.

• Cleaning of dye-flow system and filters.

• Cleaning and adjustment of optics. (The more complex the optical system, the more often adjustment is usually needed.)

• Replacement of flashlamps in flashlamp-pumped...