I heard but find nothing

[lahoop]

Hi to all
maybe two years ago I read a thread in this forum talked about a camera that can visualize what is underground up to 20 meters depth.
Again, a member wrote a thread about a two computers with some software and hardware also can visualize what is underground with clear image as a picture.
I have searched since that time tell today through internet and other resources but nothing. please if anyone find something like that things let me know.
any help would be appreciated.
THank you