Final answer:
The two main categories of multifocal lens design are Simultaneous Vision, which has concentric circles for different visual zones, and Translating, with distinct lines to separate viewing areas. Converging and diverging lenses focus on how they handle light, converging towards a point or diverging away.
Step-by-step explanation:
The two main categories of multifocal lens design are Simultaneous Vision and Translating. Simultaneous Vision lenses allow the wearer to look through both the near and distance portions of the lens at the same time. This design usually consists of concentric circles of different powers. On the other hand, Translating lenses, also known as segmented or alternating vision lenses, have a distinct line that separates the multiple vision areas, allowing the wearer to physically shift their gaze between the near and distance viewing zones.
To clarify, the terms converging lens and diverging lens relate to how lenses bend light rays. A converging lens, or a convex lens, bends light rays towards each other, converging them at a focal point. A diverging lens, or a concave lens, spreads out light rays, causing them to diverge.