LAUSR

Abstract Bessel beam femtosecond lasers being non-diffractive are well-suited for drilling high aspect ratio microholes with minor thermal impact. Hereby, the Bessel beams with different non-diffraction lengths using axicon lenses were generated with different taper angles for analyzing the drilled microholes to optimize the aspect ratio. The experimental results show that the depth of microhole is increasing with the pulse number accumulating for low energy laser pulses. With the increasing of energy laser pulse, the increment of microhole diameter is faster than that of the depth. The large aspect ratio microholes with the maximum value of 348:1 have been formed by Bessel femtosecond laser micromachining.