Abbe Number

Abbe number, abbreviated as \(V_d\), a dimensionless number, is the measure of material's dispersion (variation of refractive index versus wavelength) with high values of V indicating dispersion.  It is used to classify glass and other optically transparent materials.  It's inversely proportional to the dispersion of the material.  A high Abbe number indicates that the material has low dispersion and is less likely to separate light into its constituent colors, while a low Abbe number indicates the opposite.  The Abbe number is commonly used in the design and selection of optical materials, such as lenses and prisms, to control chromatic aberration and improve optical performance.

 

Abbe Number formula
\( V_d \;=\;  n_d - 1 \;/\; n_f - n_c \)     (Abbe Number) \( n_d \;=\; V_d \; n_f + V_d \; n_c - 1  \) \( n_f \;=\; n_d - 1 + V_d \; n_c \;/\; V_d \) \( n_c \;=\; 1 - n_d + V_d \; n_f  \;/\; V_d \)
Symbol	English	Metric
\( V_d \) = Abbe Number	\(dimensionless\)	\(dimensionless\)
\( n_d \) = Refractive Index at the Wavelengths of the Fraunhofer D Spectral Line	\(dimensionless\)	\(dimensionless\)
\( n_f \) = Refractive Index at the Wavelengths of the Fraunhofer F Spectral Line	\(dimensionless\)	\(dimensionless\)
\( n_c \) = Refractive Index at the Wavelengths of the Fraunhofer C Spectral Line	\(dimensionless\)	\(dimensionless\)