Coherence confocal-imaging system for enhanced depth discrimination in transmitted light.

A system for image-plane holography that uses a spectrally and spatially broad radiation source is analyzed and shown to provide depth discrimination in excess of that offered by conventional confocal imaging. The enhanced depth discrimination is a consequence of two factors: the simultaneous reduction of both the spatial and the temporal coherence of the source, and the special property of certain grating interferometers of presenting a spectrally dispersed light beam to the object while forming achromatic fringes at the hologram-recording plane.