  We develop a method based on the cross-spectrum of an intensity-modulated CW
laser, which can extract a signal from an extremely noisy environment and image
objects hidden in turbid media. We theoretically analyzed our scheme and
performed the experiment by scanning the object placed in between two ground
glass diffusers. The image of the object is retrieved by collecting the
amplitudes at the modulation frequency of all the cross-spectra. Our method is
non-invasive, easy-to-implement, and can work for both static and dynamic
media.
