Pulse-by-pulse optical observation of laser-irradiated thin glass substrate using oil-immersion microscopy

Abstract

To study the formation mechanism of laser-induced periodic surface structures, we carried out a pulse-by-pulse optical observation of laser-induced surface morphological changes on thin glass substrates. We adopted oil-immersion microscopy, which has a higher spatial resolution than dry microscopy, and the laser was irradiated from the air side. A thin transparent substrate of coverslip was used as the sample. When a scratched coverslip was irradiated with focused subnanosecond laser pulses of 1.064 µm wavelength, periodic structures occasionally appeared in the flat region near the focus, with a period of about 0.55 μm.

Anisotropic reversing motion in laser-induced periodic surface structures

“…14) We have also reported such pulse-by-pulse observations by simple optical microscopy using a subnanosecond laser as a light source. 15,16) Optical microscopy is easy to implement and convenient for capturing a lot of images, but provides only low spatial resolution. To mitigate the disadvantage of low spatial resolution, we adopted the combination of observation by oil-immersion microscopy and irradiation from air.…”

“…To mitigate the disadvantage of low spatial resolution, we adopted the combination of observation by oil-immersion microscopy and irradiation from air. 16) In the present study, we used the same strategy, and a femtosecond laser was used as a light source. Using this setup, we found an anisotropic reversing motion of LIPSSs whose periodicity was perpendicular to the electric field of the laser pulse.…”