<title>Reconstruction of 3-D biological images from serial sections using multiplane/multiplex holography</title>

Abstract

In biological systems 3-D data is often collected as serial sections, but reconstruction of 3-D models of the original object by computer can be very timeconsuming. Conventional holography produces excellent 3-D images quickly, but images are the same size as the object. However, multiplex holography uses photographically scaled images as the "object", eliminating the problems with objects too small or too large for conventional holography. A rectangular box of square steel tubing was used to mount optical components for a multiplex holography rig. Coherent light at 514.5 rim was provided by an argon-ion laser. The object beam illuminated 35mm transparencies of serial sections whose magnified images were projected onto a ground-glass screen, and thence to the film. The reference beam was spread by a spatial filter and reflected by a mirror onto the film. Exposures of each serial section were made using a moveable "cage" containing film holder and reference mirror to vary the screen/film distance for each exposure. Beam paths formed a parallelogram so that movements of the film/mirror cage changed reference and object beams by the same amount. The rig could be configured for reflection or transmission holograms. Both serial micrographs and computerized tomograms gave holograms where 3-D relationships between structures could be visualized. Although the range of perspectives with these holograms is less than that with some computer reconstructions, the time for hologram production with this rig (about 30 minutes) makes it an attractive addition to laboratories and hospitals where serial sections or computerized tomograms are used for 3-D reconstructions.