Dichroic Prism

It is a mirror, reflector or filter which selectively reflects different light waves, allowing a projector to transmit visible light but with less temperature. Dichroic mirrors are also used for internal convergence in multimedia projectors that work with system LCD and DLP projection.

LCD projectors - start with a source of light (lamp) and split the light into three beams. Each beam passes through its own LCD panel. The LCD panels each have hundreds of thousands of tiny pixels, the higher the resolution, the more pixels. Data determines whether light is allowed to pass through each one.

One panel has a red filter, one a green, and one a blue filter. The light is then recombined, using a dichroic prism. The combined, now in full color, passes through the lens and hits your screen.

A dichroic prism divides light into red, green, and blue, to form three pictures that utilize these corresponding colors from the LCD (HTPS) panels. Color and image are recomposed by reflecting red and blue light and transmitting green light. The prism is formed by combining four triangular poles to create one rectangular solid. High precision is required in the processing and adhesion of poles to avoid dark lines and double images caused by misaligned dichroic surfaces.

A dichroic filter or thin-film filter is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors. By comparison, Dichroic mirrors and dichroic reflectors tend to be characterized by the color(s) of light that they reflect, rather than the color(s) they pass. (See dichroism for the etymology of the term).  A dichroic color filter is mounted on the outer ring to provide rich color illumination.