Combination of Two Cylindrical Lenses at Right Angles Equals a Spherical Lens. Figure 49-5B shows two convex cylindrical lenses at right angles to
each other. The verticalcylindrical lens converges the light rays that pass through the two sides of the
lens, and the horizontal lens converges thetop and bottom rays. Thus, all the light rays come to a
singlepoint focus. In other words, two cylindrical lenses crossed atright angles to each other perform the same function as one spherical lens of the same refractive power.
