What is the abbe number n-BK7?

Abbe Number of n-BK7 Glass

n-BK7 is a popular type of borosilicate glass that is widely used in the manufacture of optical components such as lenses, prisms, and windows due to its excellent optical properties and physical characteristics. One of the key parameters that describe the optical performance of glass materials is the Abbe number.

What is the Abbe Number?

The Abbe number, also known as the V-number, is a dimensionless number that characterizes the dispersion of a material. It is a measure of how much light is spread out or refracted in different colors as it passes through a material. The Abbe number is defined as:

V = (n_D - 1) / (n_F - n_C)

where n_D, n_F, and n_C are the refractive indices of the material at the wavelengths of the Fraunhofer D-line (589.3 nm), F-line (486.1 nm), and C-line (656.3 nm) respectively.

Abbe Number of n-BK7

The Abbe number of n-BK7 glass is typically around 64.17. This relatively high Abbe number indicates that n-BK7 has low dispersion, meaning it does not spread out light into its constituent colors as much as materials with a lower Abbe number. This property makes n-BK7 an excellent choice for applications where minimal chromatic aberration is desired.

Importance of the Abbe Number

The Abbe number is crucial in optical design because it helps in selecting materials that minimize chromatic aberration, an optical effect that causes a lens to focus different colors of light at different distances. A higher Abbe number indicates lower dispersion and thus less chromatic aberration. When designing optical systems, engineers often seek materials with high Abbe numbers to improve the quality of the image.

In conclusion, the Abbe number of n-BK7 glass highlights its suitability for high-precision optical applications where low dispersion and minimal chromatic aberration are essential. Its widespread use in optical engineering underscores the importance of understanding and utilizing the Abbe number in material selection.