How does chromatic aberration occur in lenses?

Chromatic aberration occurs in lenses due to the different wavelengths of light refracting at different angles.

When light passes through a lens, it is refracted or bent due to the change in speed of light in the lens material. However, different colours of light have different wavelengths and therefore refract at slightly different angles. This means that the focal point for each colour is slightly different, causing chromatic aberration.

There are two types of chromatic aberration: longitudinal and transverse. Longitudinal chromatic aberration occurs when different colours have different focal lengths, causing the image to appear blurry and with coloured fringes. Transverse chromatic aberration occurs when the different colours are focused at different points on the image plane, causing the image to appear distorted.

To reduce chromatic aberration, lenses are often made with multiple elements of different materials and shapes, which help to refract the different colours of light more accurately. Additionally, some lenses are coated with special materials that help to reduce the amount of light that is reflected, further improving image quality.

Overall, chromatic aberration is an important consideration when designing and using lenses, as it can significantly impact image quality and clarity.