A scientist discovers a formula for correcting spherical aberration

David Lee

8.7.2019

Translation: machine translated

Image errors that lead to blurred edges should be corrected thanks to a new formula. However, this is already possible today.

In a scientific article published by the Optical Society OSA, three physicists have published a formula for constructing lenses with a special geometry that would not cause spherical aberration.

What is spherical aberration?

Spherical aberration is an aberration in optical lenses and therefore also in photo lenses. Because of the curvature of the lens, light rays are not properly redirected to the edges. Theoretically, in the diagram below, all the rays should intersect at the same point, but this is not the case. The result is that the image is less sharp at the edges than in the centre, at least when the diaphragm is open.

The solution

If this article is to be believed, one of the authors, Rafael G. González-Acuña, thought of this formula by spreading his slice of bread with nutella:

This should be the solution to the problem scientists have had since ancient Greece.

What I don't understand (apart from the formula of course): for decades there have been aspherical lenses and therefore lenses that do not exhibit spherical aberration. They are even very common and quite affordable. Here are three examples:

Lenses

Fujifilm Fujinon XF 27mm f/2.8 Black

Fujifilm Fujinon XF, APS-C / DX

31

Lenses

CHF331.–

Samyang 8mm f/3.5 Asph IF MC Fisheye CSII DH - Sony E

Sony E, APS-C / DX

1

Lenses

CHF152.–

Panasonic 25mm f/1.7 ASPH.

Micro Four Thirds, Micro Four Thirds

62

Lenses

Fujifilm Fujinon XF 27mm f/2.8 Black

31

Lenses

CHF331.–

Samyang 8mm f/3.5 Asph IF MC Fisheye CSII DH - Sony E

1

Lenses

CHF152.–

Panasonic 25mm f/1.7 ASPH.

62

Practical advantage?

I haven't found out how much better the new solution is. If you know, please write it in a comment. Perhaps this new knowledge will make it possible to make cheaper aspheric lenses. However, if these lenses look like what is shown in this diagram, I doubt they will be cheap to produce.

As always with such research findings: the practical benefits will only be felt in a few years' time. Or not.

David Lee

Senior Editor

David.Lee@digitecgalaxus.ch

My interest in IT and writing landed me in tech journalism early on (2000). I want to know how we can use technology without being used. Outside of the office, I’m a keen musician who makes up for lacking talent with excessive enthusiasm.

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