1. A method of imaging an object located in a highly scattering turbid medium, the high scattering turbid medium being an in vivo biological tissue, said method comprising the steps of: (a) illuminating the object through the highly scattering turbid medium with a pulse of light, the light emergent from the highly scattering turbid medium consisting of a ballistic component, a snake-like component and a diffusive component; (b) determining the intensity of said diffusive component at a plurality of points in time; and (c) using said intensity determinations to form an image of the object in the highly scattering turbid medium, said using step comprising using a mathematical inversion algorithm to generate an image of the highly scattering turbid medium, said mathematical algorithm being ##EQU7## wherein W is a matrix relating output at source and detector positions r.sub.s and r.sub.d, respectively, at time t to position r, .LAMBDA. is a regulation matrix, chosen for convenience to be diagonal but selected in a way related to the ratio of the noise, &lt;nn&gt; to fluctuations in the absorption (or diffusion) X.sub.j that we are trying to determine: EQU .LAMBDA..sub.ij =.lambda..sub.j .delta..sub.ij with .lambda..sub.j =&lt;nn&gt;/&lt;.DELTA.Xj.DELTA.Xj&gt; Y is the data collected at the detectors, and X.sup.k is the kth iterate toward the desired absorption information.