Spatial resolution of diffuse photon density waves

On comparison with the usual propagating scalar waves, the attenuation of d iffuse photon density waves gives rise to important differences in structur al information, such as higher spatial resolution in detection at short dis tances from objects and deviation from the Rayleigh limit at larger distanc es. This damping also establishes a minimum spatial resolution threshold fo r diffusive waves, which occurs by illumination in continuous mode, and dem onstrates that in most cases spatial resolution is not improved by increasi ng the modulation frequency. Assessments of this formulation with numerical simulations of scattering and wave-front reconstruction in the presence of noise are given. (C) 1999 Optical Society of America [S0740-3232(99)01796- 8] OCIS codes: 170.5270, 290.1990, 170.7050, 100.6640.