The invention provides a projection type liquid crystal display device having a light source (1), light separation means (4) for separating light from the light source, a liquid crystal light valve (8) for modulating light from the light separation means, light synthesising means (9) for synthesising modulated light from the liquid crystal light valve, and a projection lens (12) for projecting light from the light synthesising means. A polarising beam splitter (2) is arranged between the light source and the light separation means to separate incident light into two polarised light components perpendicular to each other. A polarisation direction converter (3) is arranged to receive the polarised light components from the polarising beam splitter and to convert the components to have the same polarisation direction for projecting them as a substantially parallel beam.