Sphere aberration

[Edgley Gonzaga]

How can I calculate the sphere aberration ?

Thanks everybody for the helping hand;) !!!!


Edgley

[eyesguy]

Hi Edgley:

To find SA:

Trace a ray from the object point and find the image distance L. Next, trace a paraxial ray from the same point and find its image distance l. Longitudinal SA = L-l. Hope this helps.

Regards,

eyesguy

[Steve Machol]

For what it's worth, spherical aberration is not really much of an issue with ophthalmic lenses because of the pupil's relatively small aperature. The main aberrations affecting ophthalmic lenses are: marginal astigmatism, power error and chromatic aberration.

[eyesguy]

I agree with Steve--I generally don't worry about SA when trying to optimize a design. Astigmatism and Lateral Color are my errors of choice.

eyesguy

[Edgley Gonzaga]

I would like to thank you guys for the answers. I was just wondering how to measure the spherical aberration. I have never read anything about how to measure it. I think that, if the aberration exist, we should know how to measure it, just in case someone ask us, and i have to say that I dont know how to do it.

Thanks everybory.

See you.

[Darryl Meister]

Hi Edgely,

Most books on geometric and ophthalmic optics should give you the exact equations, if you still want them (it was already pointed out that spherical aberration -- and coma -- aren't issues in spectacle lenses of low-to-moderate power). Although I don't have it with me now, I'd probably start with Jalie's book -- if you have access to it.

Best regards,
Darryl

[eyesguy]

Good luck getting Jalie's book(s). I searched the web for a week before locating a used copy. Smith gives the same information and is easy to get.

eyesguy

[Darryl Meister]

eyesguy said:
Good luck getting Jalie's book(s). I searched the web for a week before locating a used copy. Smith gives the same information and is easy to get.

You should be able to order Jalie's Principles of Ophthalmic Lenses book directly from the Association of British Dispensing Opticians, its publisher. They were still printing it as of last year (I haven't checked recently.) Unfortunately, I do not have their telephone number handy -- but perhaps some of our British friends do.

Best regards,
Darryl

[John R]

Even better than a phone number is their Web Site Which has a online book shop...:D If its Ophthalmic Lenses & Dispensing - M Jalie You are after its £55.00, dont know if they will deliver state side but i cant see a problem.
I have emailed them as to wether they will do this.

[John R]

2 other possible sources of this book are
Here An americian site i think and
Here a UK site using Amozon...

[Edgley Gonzaga]

Hello people!

Thanks very much for your helping hands. Recently I asked Darryl about the nicest books, well, I've just lost the oportunity to buy the Jalie's book, my boss went to the optical fair in NY last week, i had asked him to bring me this book but he didnt bring it , now i have to import it, and of course i will pay much more ofr it. BUT I WILL GET IT.

Just one question: WILL ANYONE FROM OPTIBOARD COME TO THE BRAZILIAN OPTICAL FAIR IN JULY?

Thanks everybody!!!!!

[Darryl Meister]

John R said: If its Ophthalmic Lenses & Dispensing - M Jalie You are after its £55.00, dont know if they will deliver state side but i cant see a problem.
I have emailed them as to wether they will do this.

Great link for the ABDO, John.

That's a good book by Jalie, with full color photos, but the Principles of Ophthalmic Lenses book (selling there for around £39 plus shipping) is the text to get for details on spectacle ray tracing. I'll also add that I have purchased several books from the ABDO over the years, and have been very pleased with their service.

Best regards,
Darryl

[eyesguy]

Hi John R:

I went to the web-site you mentioned and could not find an on-line bookstore. What am I doing wrong?

Regards,

eyesguy

[John R]

Top left is their crest, under that is Home, then under that is 6 links its the bottom one.
Btw which browser are you using ? just wonder if its a "Frame" problem..

But here's a Direct link

[Pete Hanlin]

Darryl would know better (since he wrote the program in question), but I believe OpticsLite, which is a spreadsheet app that is available in the OptiBoard downloads section, computes spherical aberration.

Even if it doesn't, I think you'll find the program worth downloading. I've used it often when I want to know "what will happen" if I do this or that to a lens and I don't want to bother with (or, quite frankly, am unable) to calculate the results.

[Darryl Meister]

Well, it calculates a lot of stuff, but not spherical aberration (since it generally isn't a concern for spectacle lenses). It does compute oblique astigmatism, mean power error, chromatism, Davis blur, and all that other stuff though.

Best regards,
Darryl

[John R]

John R said:
I have emailed them as to wether they will do this.

Ok here's the responce from the ABDO

There is no problem ordering books via the internet, although if you
want them sent to the states, there may be a further postage charge.
It may be easier to call the bookshop and speak to Justin Hall, 01227
738829 ext 904, as he will be able to inform you about pastage rates
etc.