An Aerial-Image Unit for Industrial Animation
George W. Tressel, Stanley J. Andrews · Journal of the SMPTE · 1964
The aerial-image unit is a valuable tool for inserting diagrams into industrial motion pictures. The principal problems associated with such a unit are design of the field lens for minimum spherical aberration, and critical alignment of the optical train. High-quality projection lenses and large aperture are also necessary to prevent color fringing caused by the condenser system.