ABO NOCE Basic Opticianry Spectacle Lens Aberrations 2

Question 1

Which aberration causes straight lines to appear curved when viewed through the periphery of a lens?

Accepted Answer

Distortion

Answer

Distortion causes straight lines to appear curved or bowed, with pincushion distortion in plus lenses and barrel distortion in minus lenses.

Question 2

Pincushion distortion is most commonly associated with which type of lens?

Accepted Answer

High plus lenses

Answer

High plus (convex) lenses produce pincushion distortion, where the edges of images appear to bow inward.

Question 3

What is the primary optical aberration corrected by aspheric lens designs?

Accepted Answer

Spherical aberration

Answer

Aspheric lens designs flatten the lens surface progressively from center to edge to reduce spherical aberration.

Question 4

Oblique astigmatism occurs when light rays pass through a lens at an angle. At what lens zone is this aberration most problematic?

Accepted Answer

Peripheral zone

Answer

Oblique astigmatism is a peripheral aberration that worsens as the angle of incidence increases away from the optical center.

Question 5

Which Seidel aberration creates a comet-shaped blur and is caused by off-axis light passing through different lens zones?

Accepted Answer

Coma

Answer

Coma produces a comet-shaped flare pattern because off-axis rays through outer lens zones focus at different lateral positions than paraxial rays.

ABO NOCE Basic Opticianry Practice Test