What is Spherical Aberration? | Optics Explained

Spherical aberrations are one of the most common forms of optical aberration. Spherical aberrations are the result of a ray height dependent effective focal length. Rays farther from the optical axis (peripheral rays) will focus to a different focal distance than rays closer to the optical axis (paraxial rays). This distribution of focal distances with varying ray height introduces a 'focal region' instead of a single focal point for all rays. Spherical lenses when used in high numerical aperture (NA) optical systems or in systems with larger focal ratios can introduce more spherical aberrations. Spherical aberrations can limit the ability to focus a beam, resulting in larger focused spot sizes. In imaging applications, spherical aberrations can reduce image quality and introduce blur in the outer regions of the image. #optics #STEM #science #OpticsExplained #photonics

[@MagicalTowel42]

What are the practical uses for spherical lenses? And what are the pros and cons of using one shape over the other?

[@thorlabs]

Spherical lenses absolutely have their place and value in optical systems, but there is not a "one size fits all" for all applications. The amount of spherical aberration added by a spherical lens, like a plano convex, is limited by the focal ratio (f/number) or numerical aperture (NA). As a result, low NA applications (small beam diameters and longer focal lengths) can perform well using spherical lenses while high NA and imaging applications may not perform as well. Bi-convex lenses are usually used for low NA finite imaging of point sources rather than collimation or focusing. I hope this helps; if you need more specific information, don't hesitate to contact Tech Support!

[@KitagumaIgen]

To my understanding it is much "simpler" to make spherical lenses than lenses with other shapes. By combining multiple lenses with different shapes an glasses aberrations can be reduced

[@thorlabs]

Thank you for your additional comment, that is correct! Due to their symmetry, multiple spherical lenses of the same radius of curvature can be polished at the same time, making them cheaper to produce at volume. Additionally, the use of multiple spherical lens elements with differing materials can reduce aberration and improve performance.

[@TheClumsyFairy]

Magnificent.

[@orjichukwujindum1371]

Cool

[@thorlabs]

Thank you for your comment, we're glad you enjoyed this!