Ultrafast Microscopy


The interaction of femtosecond (fs, 10^-15 sec.) with materials can be studied using pump-probe techniques, in which a probe laser pulse interrogates the changes imposed on a material by a pump laser pulse. Efforts in the Yalisove Lab have been focused on understanding the dynamics of fs laser induced ablation of materials using pump-probe imaging techniques, in which an image is formed from a probe pulse that has either reflected off from or passed through an ablation event. By changing the relative delay between the pump pulse (which initiates the ablation) and the probe pulse (which produces an image of the ablation), the evolution of the ablation can be studied with temporal resolution only limited by the pulse width of the laser, in this case, 150 fs. By analyzing the images as function of time, details of the ablation event can be determined, such as the optical properties (refractive index, optical thickness) of the ablating material, and the energy release necessary to produce observed air shock dynamics.