We use a home-made set-up to measure the optical second harmonic genneration from multiferroic thin films. A Ti:Sapphire laser (130fs, 700-940 nm), a cooled spectrometer (300-1000nm), and a electromagnet (0-4000g, 77-300 K) are connected together and controlled by LabView program. The measurements is aimed to discover various polarization states and spatially resolve the nano-domains in these memory devices.