Improvement in color kinescopes through optical analogy

The relationship between phosphor dots on the screen and the holes in the shadow mask has been determined by light beams emanating from small light sources located at the red, green and blue color centers. This is acceptable for tubes with small deflection angles, but becomes less acceptable for tubes with large deflection angles. This is due to the fact that in an operating tube the electrons do not appear to originate from points in a fixed deflection plane, but rather from points in a deflection plane which moves closer to the shadow mask as the deflection angle is increased. This causes a color impurity for the larger deflection angles. The color impurity has been eliminated by determining the relationship between phosphor dots on the screen and the holes in the shadow mask with an exact light analogy for the electron trajectories.