Transparency (projection)

In the 1960s and 70s the GAF OZALID "projecto-viewfoil" used a diazo process to make a clear sheet framed in cardboard and protected by a rice paper cover.

[1] In the 1980's laser printers or copiers could make foil sheets using standard xerographic processes.

Specialist transparencies are available for use with laser printers that are better able to handle the high temperatures present in the fuser unit.

Until the advent of LaTeX, math classes in particular used rolls of acetate to illustrate sufficiently long problems and to display mathematical symbols missing from common computer keyboards.

Many overhead projectors are used with a flat-panel LCD which, when used this way, is referred to as a spatial light modulator or SLM.