Additive (colour) process

 

The formation of a colour by mixing light of two or more other colours. The process of combining lights of different colours. A set of three primary colours combined equally produces white.

As a rule the three additive primary colours red, green and blue are used since they can, when mixed, produce a full range of colours including white.

A limited range of colours can be produced with two primaries. The mixing of the light occurs at the retina of the eye. The light beams can enter the eye simultaneously or successively, or else form on the retina a mosaic which is too small to be resolved.

Used in the Printing of Motion Picture Films.

 

https://www.nfsa.gov.au/sites/default/files/uploads/2010/08/23/additive-colour-process.gif

 

Dichroic Mirror 1 Reflects RED. Transmits GREEN and BLUE
Dichroic Mirror 2 Reflects RED and GREEN. (Since red has already been removed from this beam, it reflects green only). Transmits BLUE
Dichroic Mirror 3 Reflects BLUE only (further reducing band width). Transmits Usable wave lengths
Dichroic Mirror 4 Reflects RED only (reducing band width). Transmits Usable wave lengths
Dichroic Mirror 5 Reflects GREEN. Transmits RED.
Dichroic Mirror 6 Reflects BLUE. Transmits RED and Green.
No. 7 Light Valves