The Z-scan technique is a simple and popular experimental technique to measure intensity dependent nonlinear susceptibilities of materials. In this method, the sample is translated in the Z direction along the axis of a focused Gaussian beam, and the far field intensity is measured as a function of sample position. Analysis of the intensity versus sample position Z-scan curve, predicated on a local response, gives the real and imaginary parts of the third order susceptibility. In this technique the optical effects can be measured by translating a sample in and out of the focal region of an incident laser beam. Consequently, increases and decreases in the maximum intensity incident on the sample produce wavefront distortions in the sample being observed.

Holmarc's Z scan system includes precision motorized stage for linear scanning, photo diode assembly along with mechanical mounts and electronics for motion control and data acquisition. Light source normally, does not include in the scope of supply. In many cases, selection of photo-diode too depends on application.

Precision rolling contact ways using crossed rollers are used for guide way which are pre-loaded to eliminate play and wobble. Precision ground lead screw and pre-loaded nut without backlash are used to drive the unit. For mounting, base of the stage has M6 clearance slots and top of the stage has M6 tapped holes. Control of the stepper motor is achieved through serial port of a PC and data acquisition is through the parallel port. Parameters like speed, travel distance, data acquisition intervals etc. can be programmed using computer.