Subtractive Primary Color Separation with a Prism?

The combination of different colors of lights is a standard topic in introductory physics courses, and there are many articles describing different methods to help students understand it.^1–5 Monitors are a good example to explain how the different colors of lights combine to form a variety of colors, since they use three separate illuminators to emit red (R), green (G), and blue (B) light (which we refer to here as the trichromat of light).⁶ In this work, we have observed various colors of rectangles drawn on a liquid crystal display (LCD) monitor screen through an equilateral triangular prism. This observation gives results that seem at first glance to conflict with the way LCD monitors display various colors by controlling the brightness of RGB pixels. This inconsistency has been explained qualitatively by considering the background, i.e., whether it is white or black. We believe that this observation and explanation...