Overhead Projector - Dissected

Purpose

To show how an overhead projector works and to view its components.

Equipment

Overhead projector with screws removed, transparency grid.◙

Setup Time

5 min.

Images

l7-33

Description

Components on the table of the overhead projector, including the Fresnel field lens and the anti-glare sheet, can be removed, and the projector operated without them to illustrate their function. The vignetting effect without the field lens is very dramatic. The field lens focuses light passing through all points on the table through the adjustable lens and mirror system, so that the final image on the screen will be uniformly bright. Use a transparency grid on the table as the object.