Dispersion - Chromatic Abberation

[apples and pears]

Hi all.

I'd like to ask why an achromatic doublet (one concave & and one convex lens of the same curvature cemented together) reduces chromatic abberation.
Do any of you guys know how and why it does this (reduces chromatic abberation)? Thank you.

Just for your info: Chromatic abberation occurs when light passing through a lens is separated into different colours due to dispersion.

 

[Doc Al]

The chromatic abberations of diverging and converging lenses go in opposite directions.

 

[M98Ranger]

This results in a blurry image with colored fringes.

Hi there,

An achromatic doublet is able to reduce chromatic aberration because it combines two lenses with different dispersive properties, allowing them to counteract each other's effects. The concave and convex lenses have opposite dispersive properties, meaning that they bend different colors of light in opposite directions. When these two lenses are cemented together, their dispersive properties cancel each other out, resulting in a more focused and color-corrected image.

This phenomenon is known as dispersion, where different colors of light have different wavelengths and therefore are bent at different angles as they pass through a lens. When these colors are not properly corrected, they can create chromatic aberration, as mentioned in your post.

By using an achromatic doublet, the dispersion of one lens is counteracted by the other, resulting in a more uniform refraction of all colors of light. This leads to a sharper and more accurate image without any color fringes.

I hope this helps to answer your question. Let me know if you have any further inquiries.