SEDL / STP / STP469-EB / STP48610S

Laser-Beam Self-Focusing and Glass Damage Caused by Electrostrictively Driven Acoustic Waves

Kerr, Edwin L.
Associate Engineer, Perkin-Elmer Corporation, Wilton, Conn.

Pages: 20    Published: Jan 1969

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Abstract

A self-focusing mechanism for high-power laser pulses is presented. The mechanism involves electrostrictively excited waves in the glassy medium. The focusing power of the waves increases with time during the laser pulse. Computer movies show the time development of the beam profile. Beams of more than threshold power are brought to sharp, rapidly moving foci in the medium. At the foci, the medium's electric field breakdown strength or elastic rupture strength may be exceeded, causing permanent damage. The threshold power depends only on the wavelength, and the medium's density, elastic moduli, and refractive index. In its region of validity, the theory agrees with experiments to within a factor of 3 or less.