Design of an RGB colour separation prism based on the maximum ratio of aperture to length

We redesigned the RGB colour separation prism to decrease its size without reducing the light passing through and still obtain the efficient colour separation. The ideal dimensions of the prism based on the principles of the maximum ratios of aperture to length and aperture to height were calculated. The two aperture values were similar, but the field-of-view angle is 30.74 degrees when the ratio of aperture to length is maximum which is 11.64 degrees greater than the other principle. Therefore, we focused the design on the former. TFCalc software was used to design and optimize the colour separation films and we got the films with great performance of colour separation and depolarization. Finally, simulations in ZEMAX software showed that the prism aperture value reached 99.5% of the theoretical. Our strategy validates the consideration of the ratio of the aperture to length to get smaller efficient RGB colour separation prisms.