Projection system using readily available items - uses liquid crystal layer with electrodes for light beam modulation

摘要

The projection system comprises a light source, a condenser and an optical system projecting and focussing the beam from the source on a screen. A modulator between the condenser and the projection head modulates the beam. The modulator consists of a thin liquid crystal layer between a transparent upper surface with at least one conducting surface in contact with the layer, and a lower plate with conducting surface areas opposite the above and in contact with the other surface of the layer. A voltage source generates a potential difference between the selected opposite conducting surfaces at a greater value than the liquid crystal threshold voltage.