Re:Mexican physicist’s solution to 2,000-yo problem could le...
by gus_massa on Friday August 09, 2019 @07:33AM
(#20653319)
Opening sentence in the article:
> It’s a problem that plagues even the priciest of lenses, manufactured to the most exacting specifications: the center of the frame might be razor-sharp, but the corners and edges always look a little soft.
The method in the article doesn't solve this. The method only give an analytic solution for the center and only for one color. All the other points of the frame and all the other colors look a little soft.
It's an interesting mathematical result, but note that gives a solution for the problem of the spherical aberration, but real lens have also chromatic aberration. I.E. the speed of light for each color inside the glass is slightly different, so the value n (refraction index) in the equation is different, so in the equation you get a different surface for each color.
In the real lens you must pick one surface, so the effect is that one color is perfectly focused and the other colors are not focused and you get some rainbow-like effects.
The solution is to use combination of a few lens of different glasses, to compensate the differences. It's not easy to design these kind of system, because they must compensante also for other types of aberrations.
> It’s a problem that plagues even the priciest of lenses, manufactured to the most exacting specifications: the center of the frame might be razor-sharp, but the corners and edges always look a little soft.
The method in the article doesn't solve this. The method only give an analytic solution for the center and only for one color. All the other points of the frame and all the other colors look a little soft.
Previous discussion https://news.ycombinator.com/item?id=20369960 (845 points, 33 days ago, 210 comments)
I'll repost my previous comment:
It's an interesting mathematical result, but note that gives a solution for the problem of the spherical aberration, but real lens have also chromatic aberration. I.E. the speed of light for each color inside the glass is slightly different, so the value n (refraction index) in the equation is different, so in the equation you get a different surface for each color.
In the real lens you must pick one surface, so the effect is that one color is perfectly focused and the other colors are not focused and you get some rainbow-like effects.
The solution is to use combination of a few lens of different glasses, to compensate the differences. It's not easy to design these kind of system, because they must compensante also for other types of aberrations.
More details:
https://en.wikipedia.org/wiki/Chromatic_aberration
https://kenrockwell.com/tech/lenstech.htm