Projection apparatus using L-shaped dichroic prism set having a cubically glass block juxtaposed to a dichroic prism for passing light beams without changing direction of the light beams

The present invention relates to liquid crystal projection system and, more particularly, to a transmission-type liquid crystal projection display using an L-shaped dichroic prism set. The present invention proposes a transmission-type liquid crystal projection display, which comprises an incident light source, a light-separating means, three transmission-type liquid crystal display, an L-shaped dichroic polarizing prism set, an optical path adjusting means, and a projection lens. The light source provides a single polarized light. The light-separating means separates the polarized light into three colored lights of the three primary wavelengths. The three liquid crystal displays respective correspond to the three colored lights. The optical path adjusting means is used to let the three colored lights travel through the corresponding three liquid crystal displays and then be incident on the L-shaped dichroic polarizing prism set so that the three colored lights can be synthesized into a single output light beam. The projection lens projects the output light beam onto a screen. The present invention has the effects of high efficiency, low cost, and simplified fabrication process.