Abstract
A hydrophone is used to detect the acoustic emission for the combined pulsed laser (CPL)-BK7 glass interaction. The CPL is composed of a nanosecond (ns) laser and a millisecond (ms) laser, which are separated with a certain period of time. Owing to the material defects affected mechanism, fluctuations are observed for the transmission time and the intensity of the acoustic emission during the ns laser interaction period. A weak and a strong acoustic emissions with spectrums dominated in the ranges of 10kHz∼60kHz and less than 8kHz, respectively, are detected during the remaining millisecond laser irradiation period. The two different behaviors of the acoustic emission are analyzed together with the evolution of the plume emission captured by the high speed camera during the laser irradiation and the ablated morphology on the sample. Results show that the high-frequency acoustic signal arises from a weak interaction process that a short lifetime plume emission and a shallow pit at the sample surface are observed. While the low-frequency acoustic signal is associated with a strong interaction process that an intense plume emission and a conical shaped cavity are detected. The consistent behaviors for the acoustic emission, the plume emission and the ablated size in dependence on the delay make the acoustic signal detection a reliable method in monitoring the CPL-BK7 glass interaction process and estimating the ablation results.
Highlights
Laser-induced damage of optical materials has been investigated for tens of years since the invention of the laser
A high speed camera was put at the side of the sample to capture the evolution of the plume, which can be ignited during the ns laser-BK7 glass or the combined pulsed laser (CPL)-BK7 glass interaction
The feature of the acoustic emission generated by the CPL-BK7 glass interaction is studied by using a hydrophone
Summary
Laser-induced damage of optical materials has been investigated for tens of years since the invention of the laser. The interaction process is generally believed to be affected by the material defects (or precursors). These defects can be categorized into different classes which will initiate damage at different levels of fluences.[5] Long pulse lasers are studied to interact with optical materials.[6,7] Results show that isolated damage sites can be observed when the laser fluence is not so high, indicating a material defects affected mechanism. The advantages of double pulses and pulses trains in processing quality and efficiency have been
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
