Pulsewidth and pulseshape dependencies of laser induced damage threshold to transparent optical materials

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:552099

Koldunov, M F; Manenkov, A A; Pokotilo, I L ^[1]

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1. General Physics Institute of Russian Academy, Moscow (Russian Federation)

Theory of pulswidth dependence of laser induced damage threshold (LIDT) in transparent solids is presented. The damage is supposed to be initiated by thermal explosion of absorbing inclusions. The investigation of thermal explosion is based on an analysis of the heat transfer equation and a new approach to solving this equation is developed allowing to study kinetics of thermal explosion without any modeling presentation of an absorption mechanism. It is shown that the key parameter determining a dependence of LIDT upon a laser pulsewidth, {tau}{sub p}, is the heat transfer time, {tau}, from an inclusion to a surrounding medium. At {tau}{sub p} {much_gt}{tau} a damage threshold is characterized by a laser radiation intensity, whereas at {tau}{sub p}{much_lt}{tau} - by an energy density. The pulsewidth dependence of the LIDT has been investigated for rectangular and gaussian shapes of laser pulses and it has been established that the dependencies considerably differ in these two cases in a range of {tau}{sub p}{approximately}{tau}. An effect of damage statistics, connected with a random spatial distribution of inclusions in a material, is also investigated. For the case of one-type inclusions it is shown: the statistics does not change a functional form of the pulsewidth dependence of the LIDT and correct only the LIDT value by a spot-size factor. Theoretical results are compared with experimental data published by different research groups for the laser damage in a nanosecond-picosecond region.

• Research Organization: International Society for Optical Engineering, Washington, DC (United States)
• OSTI ID: 552099
• Report Number(s): CONF-9510106--Vol.2714
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
DAMAGE
HEAT TRANSFER
LASER RADIATION
OPTICAL SYSTEMS
PULSE TECHNIQUES
THERMODYNAMIC PROPERTIES