Lenses polishing

[dzikus18]

Dear readers,


can anyone recommend me some literature on polishing eyeglass lenses. I am interested in renewing lenses, among others from photographic lenses. They can be very old books, rather handcrafted, not about CNC technologies.

Best regards,
Piotr Molski

[KrystleClear]

Do you mean polishing older scratched lenses to remove scratches/restore luster? For eyeglasses, if you polish an existing lens to buff out scratches, you will be altering the refractive power because you are wearing away some of the lens. I would imagine this would affect the camera's ability to focus clearly if done on a camera lens.

[dzikus18]

Dear Krystle,

please correct me if I am wrong, but to my knowledge a change in thickness by 0.1 and 0.5 mm while maintaining the radius in the standard lens +3.00 dptr gives respectively about 0,01 or less dptr and 0,02 dptr (for 0.5 mm). So it should not be a problem.

Best regards,
Piotr Molski

[Lensman11]

It is almost impossible to repolish an eyeglass lens. If it is a plastic material it will have hard coat over the lens material which would prevent any attempt to repolish. You would need tooling to match the lens curves and a way to mount the lens on a fixture which is next to impossible once the lens it cut to shape of a frame. Camera lenses are difficult as well they are usually are aspheric and have to be processed on CNC machinery in addition they have AR coating which would be damaged in any attempt to repolish.

[NAICITPO]

Dear Krystle,

please correct me if I am wrong, but to my knowledge a change in thickness by 0.1 and 0.5 mm while maintaining the radius in the standard lens +3.00 dptr gives respectively about 0,01 or less dptr and 0,02 dptr (for 0.5 mm). So it should not be a problem.

Best regards,
Piotr Molski

You sound like an engineer and not an optician. A finished lens has several layers of coatings added on top and back of the lens itself. This is an example of anti-reflective coatings added on top of a lens. If you were to polish the lens that has scratches and even if you were exact and didn't change the refractive power (which as lensman11 pointed out is not likely), you would ruin the coatings. So you would then STILL have a lens that you cannot see through but it would most likely be worse than just looking through the scratch.

[NAICITPO]

Maybe this would be possible on glass lenses with no coatings if you had the right tools to match the base curve @lensman11?

[optical24/7]

Most good camera lenses are glass, not plastic. Most all have AR coatings. Sometimes, wear scratches, worn areas, are only on the AR. There are AR strippers out there. The cheapest way to proceed is to strip the AR off 1st (you can safely do this on glass lenses). If you find no defects (scratches) on the stripped lens, all you would have to do is re-AR coat the lenses.

Back “in the day”, we removed very fine hairline scratches with a rubber ball, cut in half and attached to a spindle motor and used wet polishing rouge (glass only lenses). You had to remove some lens material to get the scratch out. The human eye is more forgiving of the lens curve deviation caused by this type of polishing than an exacting instrument’s lens like a camera.

[dzikus18]

Dear Readers,

I would like to be an engineer. Thank you for that information. I see that the problem is a technical problem, not an optical one. I know from car painting that if there are minor imperfections in the paint, you can apply a thicker layer of paint and then even it out by sanding. But here are coatings.


I suspect that the AR and HC layer may be easily moved out using chemicals. Then micro-filling scratches, maybe small polishing, re-HC, re-AR, etc. Theoretically possible, but practically?

There are even more advanced technologies. Recently I read that the HC layer can be applied using 3D printing.


I still keep looking for old books, because glass needs to be processed differently.


Yours sincerely,
Piotr Molski