Ultrashort pulse laser ionization microscopy

摘要

Fundamental principles and advantages of the laser induced air ionization microcopy (LIAIM) and laser inducedbreakdown microscopy (LIBM) are introduced. Potential applications of these two new types of nonlinear imagingmethods using ultrashort laser pulses in imaging both dielectric materials and bio-samples are demonstrated with somerepresentative experimental results. Effects of different laser pulse widths on the discrimination power for laser-writtenmicrostructures inside transparent materials and the elemental composition are also investigated. It is shown thatfemtosecond laser induced ionization probe detects the variation of elemental composition of the sample materials withrelatively higher contrast ratio, whereas the ionization probe generated by picosecond laser pulses is more sensitive to thematerial density or structural change. These observations can be well explained by the different roles of multi-photonionization and avalanche ionization involved in material breakdown.