Which lens material is most prone to chromatic aberration?

Which lens material is most prone to chromatic aberration?

• A. Ophthalmic crown glass
• B. CR-39
• C. Polycarbonate
• D. Trivex

Answer: (C)

Chromatic aberration happens because different colors bend differently as light passes through a lens. The extent of this dispersion is captured by the Abbe number of the material—the higher the Abbe number, the less dispersion and chromatic aberration; the lower the Abbe number, the more dispersion. Among common spectacle lens materials, crown glass and CR-39 have relatively high Abbe numbers, meaning they exhibit less color fringing. Trivex sits in the middle. Polycarbonate, however, has a low Abbe number, so it disperses blue and red light much more, resulting in more pronounced chromatic aberration. This is why polycarbonate lenses are the most prone to chromatic aberration of the options listed.

Chromatic aberration happens because different colors bend differently as light passes through a lens. The extent of this dispersion is captured by the Abbe number of the material—the higher the Abbe number, the less dispersion and chromatic aberration; the lower the Abbe number, the more dispersion.

Among common spectacle lens materials, crown glass and CR-39 have relatively high Abbe numbers, meaning they exhibit less color fringing. Trivex sits in the middle. Polycarbonate, however, has a low Abbe number, so it disperses blue and red light much more, resulting in more pronounced chromatic aberration. This is why polycarbonate lenses are the most prone to chromatic aberration of the options listed.