Nomarski interferometer with sub-micron spatial resolution for time-resolved complex-amplitude imaging of femtosecond laser-induced air plasma

In this study, we established Nomarski interferometer with sub-micron spatial resolution by using a wide-separation-angle (5 degrees) Wollaston prism and performed time-resolved complex-amplitude imaging of air plasma. We achieved a spatial resolution of 0.87 μm and succeeded in observing the internal structure of air plasma on the structure size of few-microns. Our results were also compared with numerical calculations of plasma generation based on the nonlinear Schrödinger equation in paraxial approximation and were found to be in good agreement.