Eclipsing Z-scan measurement of lambda/10(4) wave-front distortion

We introduce a simple modification to the Z-scan technique that results in a sensitivity enhancement that permits measurement of nonlinearly induced wave-front distortion of =lambda/10(4). This sensitivity was achieved with 10-Hz repetition-rate pulsed laser sources. Sensitivity to nonlinear absorption is also enhanced by a factor of =3. This method permits characterization of nonlinear thin films without the need for waveguiding.