A method for measuring the nonlinear refractive index from the contrast of an amplitude object image in the optical scheme with phase Zernike filters based on electronic Kerr nonlinearity

We propose a method for determining the nonlinear refractive index from the image contrast of amplitude objects in the phase-contrast scheme with a sample acting as a phase Zernike filter based on the electronic Kerr nonlinearity. This method implies the measurement of the calibration dependence of the contrast of an amplitude object image on the laser pulse energy for a test sample with a known nonlinearity and makes it possible to find the nonlinear refractive index of samples under study using a single laser pulse. (paper)