Figure 22

(a) Schematic of the spatial shaping femtosecond laser pulses microdrilling setups; (b) Morphology images of microholes drilled with a single pulse Bessel beam and Gaussian beam, respectively; (c) Intensity distribution simulations of the Bessel beam and Gaussian beam; (d) The hollowness characterization of microholes drilled by single-pulse Bessel beam. Reproduced from Ref. 132 (with the permission of Springer).