Actually, I knew Stanley Pons and Martin Fleischmann personally. They were not frauds. They were legitimate scientists. However, their work on cold fusion did bring them into disrepute.The hyperbole is not in the scientific papers, but in the hysterical musings of journalists and news reporters........universally disliked by scientists.
The cold fusion lot were not scientists...they were frauds.
The physicist worked out a mathematical solution — which is great — for a problem that is solved via other methods every day by lens designers. That’s a great way to earn his doctorate.
The closed form solution to spherical aberration has been inferred ever since Sir Isaac Newton deduced that the paraboloidal surface corrects on-axis aberrations entirely, confirmed when Seidel derived the aberration coefficients in the 19th century...
Good question.I read once in a paper about Bokeh that spherical aberration is often not fully corrected in the lens design in order to make for better Bokeh. So what does a lens of this new type do, relative to the Bokeh quality?
It is often said that maximum center sharpness comes at the cost of among other things bokeh, colours and corner sharpness.
The precise explanation why that is, I have never been able to find though.
just take pinhole camera.So a Mexican physicist has apparently developed a new formula that completely eliminates spherical aberration. This could be the final days of large complicated lenses and the begining of cheap, fast, and sharp lenses.
https://gizmodo.com/a-mexican-physicist-solved-a-2-000-year-old-problem-tha-1837031984/amp
I'm sure it won't reduce everything to single elements because there are other aberrations to worry about, as well as focusing and zoom issues. But we'll soon say goodbye to soft corners!
That is almost a truism.Optics designs always involve trade off. Which tradeoff are done depend on the designer not automatic results.
The basic reason is that different aberrations react to changes in the optical formula in different ways. Consequently, roughly speaking, it would only be by luck that one could get all of the aberrations to go to zero at the same time. (That's not quite true, because there is more than luck involved, but it is a reasonable way to look at it.)It is often said that maximum center sharpness comes at the cost of among other things bokeh, colours and corner sharpness.
The precise explanation why that is, I have never been able to find though.
The basic reason is that different aberrations react to changes in the optical formula in different ways. Consequently, roughly speaking, it would only be by luck that one could get all of the aberrations to go to zero at the same time. (That's not quite true, because there is more than luck involved, but it is a reasonable way to look at it.)
Some aberrations are relatively easy to correct. For example, there is a simple formula that governs how field curvature depends on the curvature of the optical surfaces and the refractive indexes of the lenses. You don't even need to do ray tracing to do that one. It's just a fairly simple algebraic calculation. Unfortunately, correcting curvature of field does not automatically correct for the closely related aberration of astigmatism.
There is a simple way to give a simultaneous correction for spherical aberration and comma (perfect correction mind you), but it only works at a specific conjugate ratio, and it only works when the image is a virtual image, not as a real image, so it can only be use as part of a larger optical system, and it doesn't correct for the other aberrations.
There is a simple way to correct for comma (a symmetrical optical system) but it only works at unit magnification.
There is a fairly simple way to correct for chromatic aberration using just algeraic equations, but it can only correct for two colors, and it doesn't correct for other aberrations. Fortunately one can often combine this approach with bending of the optical components to correct for sperical aberration, but it leaves some residual higher order spherical aberration, and it doesn't correct for other aberrations.
It's possible to correct for all of the third order (seidel) aberrations without getting too fancy. For example a cook triplet does it, but it still leaves higher order aberrations, and as a practical matter sometimes they will leave some of the third order (Seidel) aberrations partially uncorrected (or possibly over-corrected) in order to reduce some of the higher order aberrations.
There is a concept in optimization theory which says that (unless you get lucky) you have to have at least as many degrees of freedeom (i.e. parameters in a design that you can vary) as there are are properties that need to be optimized, and sometimes even that isn't enough degrees of freedom.
I wonder what specific details are wrong.Alan’s analysis sounds good, but the details are all wrong.
I have heard of Snake Oil before - perhaps they have found a way to 3D digital print these new lens designs. I have now switched on my cynicism module to full volume.
Yes, I agree that a Cooke triplet has enough degrees of freedom to correct for all third order aberrations. In fact, I mentioned that in my post. However, I believe it is seldom done in practice because most designers consider it a better compromise is to balance the third order aberrations against higher order aberrations to get a better overall image quality....The Cooke triplet has just enough variables to correct all the third order aberrations. Sph Ab, Coma, Astigmatism, Field Curvature, Distortion, and the two chromatic aberrations. In a well-designed Cooke, all that remains are higher order stuff...
Well, that all depends. If all one wants to do is correct for curvature of field, then it is exceedingly easy to correct for field curvature. Here is an example that one can write down without doing any calculations....Field curvature contributes more than any other to design complexity...
Yes, I would say it is somewhat the same thing.Thank you for the kind and insightful reply.
Most optimization processes is a game of rock, paper and scissors, often with many more parameters to set though.
You can have two or more set to your liking, but once you try to correct them all at once you run into trouble, or your design gets unreasonably expensive and complex by trying to brute force things.
For a simple example, with speaker design, there is Hoffman’s Iron Law where you can set cabinet size, sensitivity and bass extension.
You can have two of them as you like, but the third will always have to be compromised or “set free”.
Is this somewhat the same thing? Or have I misunderstood?
Here's a quote from a textbook on optics that reinforces the point I made.Yes, I agree that a Cooke triplet has enough degrees of freedom to correct for all third order aberrations. In fact, I mentioned that in my post. However, I believe it is seldom done in practice because most designers consider it a better compromise is to balance the third order aberrations against higher order aberrations to get a better overall image quality.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?