Large_Image_Projection
A large-format slide projector (also often called large-format projector or large-image projector) is a kind of slide projector for large image projection which has a very powerful light source (up to 12 thousand watts using arc lamps). The light source generates a lot of heat even when filtered to only visible light; the projected transparency is protected from overheating by the heat being distributed across its large area, and cooling fans. Slide formats include 18 × 18 cm (7.1 × 7.1") or 24 × 24 cm (9.4 × 9.4").