Patent ID: 7357516

Claim:
A lighting optical system, comprising: a light separating means for separating incident light into three colored lights according to wavelength bands, and progressing the three separate colored lights for the same amount of distance from a light source of the incident light through different optical paths, and emitting the three separate colored lights to a first, a second and a third LCD, a first, a second and a third LCD for respectively receiving the three colored lights from the light separating means, and forming images therefrom; and a light combining means for synthesizing the three colored lights emitted from the first, second and third LCDs, and outputting the synthesized light outside, wherein the light separating means comprises: a first parallelogram-shaped prism with one inclined surface being formed of a first color separating plane and another inclined surface being formed of a total reflection plane; and a second parallelogram-shaped prism with a second color separating plane formed on one inclined surface; and a triangle-shaped prism, wherein optical paths are not exposed to air.