A Holographic Microscope for Just $250
November 8th, 2012Via: MIT Technology Review:
Traditional microscopy is a powerful tool for imaging small objects, such as cells. However, anybody who has used one will know its limitations: a tiny field of view and a shallow depth of field. That makes it hard to get a sense of the three dimensional shape of objects like cells.
One clever way round this is to make a hologram of the sample. The idea here is to split a laser beam in two, use one as a reference beam and bounce the other off the sample to record the pattern of phase shifts that this produces using a digital camera.
Recombining the beams produces an interference pattern that can be analysed to retrieve three-dimensional information about the sample in high resolution.

or you could just use a focus stacking rig attached to a microscope.
http://www.microscopy-uk.org.uk/mag/artjun09/mm-macrostack.html