Transmission of pulsed CO₂ laser beams through "opaque" liquids by a cavitation effect

The formation of a stationary cavity by a sequence of CO₂ laser pulses was investigated in liquids of different viscosity and surface tension. Decreasing the surface tension of the liquid and increasing its viscosity increases the depth of the cavity and decreases the threshold energy needed for its formation. A theoretical model based on the Bernoulli-Stokes equation was developed. Good agreement between experimental and theoretical results was obtained. A method of reducing thermal damage, involving liquid layer effects during laser cutting of different materials, is proposed.