Imaging-eclipsing-Z-scan method for measurement of the nonlinear refractive index of materials

We present a new variation of the Z-scan technique, which provides a sensitive method for measurement of the nonlinear refractive index of materials. The method is based on imaging of a top hat beam onto a blocking disk; therefore, it is very sensitive. In addition to greater sensitivity the method offers the advantage that it does not require a Gaussian beam, therefore it can be used with low energy lasers with any beam profile.