Simultaneous stereoscopic fundus camera incorporating a single optical axis.

The method of stereoscopic fundus photography, where both photographs are taken simultaneously, yields the most consistent and reproducible record of depths in the fundus. However, all systems devised to date have had undesirable photographic aberrations. For the most part, this has resulted because the optical axis of each image is not the same as that of the objective lens. A single-axis system has now been devised to minimize distortions in the stereoscopic photographs, which therefore makes stereophotogrammetry relatively simple. This design also has other advantages such as simplified alignment procedures, the use of Barlow lenses for multiple magnifications, and various paired apertures for obtaining photographs especially adapted to unusual situations.