Which material corresponds to n=1.53 and abbe value 44?

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

Answer: (D)

Understanding dispersion and refractive index helps identify lens materials. The Abbe number measures chromatic dispersion: lower values mean more color fringing, while higher values mean less. An Abbe around 44 indicates moderate dispersion, not as high as CR-39 or crown glass, and not as low as polycarbonate. The refractive index of about 1.53 is typical for several plastics, but the combination with a dispersion of about 44 points to a specific material. Trivex is known for having n ≈ 1.532 and Abbe ≈ 44, making it the best match for these properties. Crown glass has a higher Abbe (58), CR-39 has a higher Abbe (58–59) with a similar or slightly lower index, and polycarbonate has a lower Abbe (30) with a higher index (1.586). So the material that fits both the index and dispersion values is Trivex.