A method of recording and reconstructing the wave front emanating from an illuminated object. Coherent light from a laser is split in two; one is a reference beam and the other illuminates the object. The waves scattered by the object and the reference beam are recombined to form an interference pattern on a photographic plate, the hologram; this records both the amplitude and the phase of the scattered light.

When the hologram is then illuminated by light from a laser or other point source, two images are produced - one is virtual but the other is real and can be viewed directly. Thus a 3-dimensional image of the object can be produced.