Which material has the lowest ABBE value?

• A. Polycarbonate
• B. CR-39
• C. Glass
• D. Acrylic

Answer: (A)

Dispersion is the way a material splits white light into its colors, and the Abbe value quantifies how strongly that dispersion occurs. A higher Abbe number means less color fringing and better chromatic correction; a lower Abbe number means more dispersion and visible color fringes.

Polycarbonate has a notably low Abbe value, around 30, which means it exhibits more chromatic dispersion than the other common lens materials. That’s why it’s the material with the lowest Abbe value among the options. In contrast, CR-39, acrylic, and glass all have higher Abbe numbers (generally in the 50s to 60s), offering better color correction and less dispersion, though each has its own trade-offs in terms of weight, impact resistance, and cost.