Which design can be used to compensate for spherical aberration in high powered lenses by modifying the surface without changing the power?

Which design can be used to compensate for spherical aberration in high powered lenses by modifying the surface without changing the power?

• A. Aspheric lenses
• B. Spherical lenses
• C. Plano lenses
• D. Cylindrical lenses

Answer: (A)

Using aspheric surfaces lets you reduce spherical aberration without altering the lens power. Spherical aberration happens because a spherical surface doesn't bend light uniformly from all parts of the lens, so edge rays focus at a different point than central rays. An aspheric surface changes its curvature as you move away from the optical axis, adjusting refraction for peripheral rays more precisely. This helps align the focal points of rays across the aperture, sharpening image quality. Crucially, the aspheric profile can be designed so the paraxial (center) focal length—and thus the overall power—remains the same, while the aberration is minimized. Spherical lenses inherently have more spherical aberration; plano lenses have zero power; cylindrical lenses address astigmatism in a different way and don’t target spherical aberration in the same sense.

Using aspheric surfaces lets you reduce spherical aberration without altering the lens power.

Spherical aberration happens because a spherical surface doesn't bend light uniformly from all parts of the lens, so edge rays focus at a different point than central rays. An aspheric surface changes its curvature as you move away from the optical axis, adjusting refraction for peripheral rays more precisely. This helps align the focal points of rays across the aperture, sharpening image quality. Crucially, the aspheric profile can be designed so the paraxial (center) focal length—and thus the overall power—remains the same, while the aberration is minimized.

Spherical lenses inherently have more spherical aberration; plano lenses have zero power; cylindrical lenses address astigmatism in a different way and don’t target spherical aberration in the same sense.