Abstract:A combination of 50 fs cross correlation time gating and lock in amplifier detection is shown to be a versatile technique to image objects through various highly scattering medium.The ballistic component and snake component of the ultrafast laser pulse,which contain the information of the objects,are effectively selected,while the diffuse component,which contributes bright background noise to the image,is eliminated by time gating using femtosecond cross correlation secondharmonic generation.