Machining of micro-holes on a thin glass plate by femtosecond laser pulses

Abstract

Holes of few tens of micrometers have been drilled through a thin glass plate by femtosecond laser pulses in air and helium environment. A femtoseconed laser (Clark-MXR, CPA 2001) which delivered 775 nm, 150 fs pulses at 1 kHz was used to machine holes through soda-lime glass plates of about 150 micrometer thick. Laser pulses were focused by a plano-convex lens on to the glass plate in air or under helium gas flow. Number of irradiating laser pulses was controlled by an electric shutter. The shape of drilled holes was observed by a laser-microscope and a SEM.Holes have conical shapes with crack-free side except shell-like cracks, which appeared at exit end of them. Hole diameters at the front surface are smaller than laser spot size at the surface and increases with laser pulse energy under the same projection conditions. Development of the hole with increasing pulse numbers shows several distinct stages. Small debris scattered around the drilled holes is observed and its range depends on the laser peak power.Holes of few tens of micrometers have been drilled through a thin glass plate by femtosecond laser pulses in air and helium environment. A femtoseconed laser (Clark-MXR, CPA 2001) which delivered 775 nm, 150 fs pulses at 1 kHz was used to machine holes through soda-lime glass plates of about 150 micrometer thick. Laser pulses were focused by a plano-convex lens on to the glass plate in air or under helium gas flow. Number of irradiating laser pulses was controlled by an electric shutter. The shape of drilled holes was observed by a laser-microscope and a SEM.Holes have conical shapes with crack-free side except shell-like cracks, which appeared at exit end of them. Hole diameters at the front surface are smaller than laser spot size at the surface and increases with laser pulse energy under the same projection conditions. Development of the hole with increasing pulse numbers shows several distinct stages. Small debris scattered around the drilled holes is observed and its range depends on the laser peak p...