Comparative study of confocal and heterodyne microscopy for imaging through scattering media

We investigate limits of the confocal microscope when applied to imaging through scattering layers and compare its performance with that of a correlation (heterodyne) microscope. Confocal laser scanning microscopy is shown to make possible imaging through scattering media owing to the spatial filtering of the signal back-reflected from the sample. Its performance is limited by the noise of the detection system and/or insufficient rejection of scattered light, depending on the sample under investigation. Correlation microscopy with narrow or broad bandwidth light can extend these limits by selective, optical amplification of the image information. (C) 1996 Optical Society of America