Which statement about aspheric lenses is true based on their relation to spherical aberration?

Which statement about aspheric lenses is true based on their relation to spherical aberration?

• A. They have no effect on aberrations
• B. They modify thickness only
• C. They compensate spherical aberration by altering surface without changing power
• D. They only correct astigmatism

Answer: (C)

Spherical aberration happens because a spherical surface bends peripheral rays differently from central rays, so they don’t all meet at the same focal point. An aspheric lens solves this by shaping the surface so its curvature changes with distance from the axis, tuning how light is bent across the entire aperture. This tailored surface profile reduces the mismatch in focal points, boosting image quality. Importantly, this improvement is achieved without necessarily changing the lens’s prescribed power—the same dioptric strength can be preserved while the surface is altered to correct the aberration. So the statement that aspheric lenses compensate spherical aberration by altering the surface without changing power captures the core idea.

Spherical aberration happens because a spherical surface bends peripheral rays differently from central rays, so they don’t all meet at the same focal point. An aspheric lens solves this by shaping the surface so its curvature changes with distance from the axis, tuning how light is bent across the entire aperture. This tailored surface profile reduces the mismatch in focal points, boosting image quality. Importantly, this improvement is achieved without necessarily changing the lens’s prescribed power—the same dioptric strength can be preserved while the surface is altered to correct the aberration. So the statement that aspheric lenses compensate spherical aberration by altering the surface without changing power captures the core idea.