polishing scratched eyepieces

[Sabatini]

Hello everyone.
I have a 10x microscope eyepieces. The eyepieces have several scratches on the front element, some deep and some superficial.
I've been doing some research and it may be worth polishing them up a bit,
Someone has experience in this procedure?.if there is a chance it can be fixed by polishing, without making it any worse, I'll give it a try.
Some ideas of the method to use are Polishing with Cerium Oxide.
Warning.!
"You are aware that when buffing with Cerium Oxide under friction, the surface of the lens actually flows a little bit, to fill in gaps? Kinda like "low temperature" melting. Might mess up the lens, might not. Worth a try."
Someone else recommends:
"You can buy very fine diamond paste. it is used for gem stone faceting which I do. it is MUCH finer than cerium oxide and much better for this purpose. you can buy cheap sets of various grades of grit quite cheaply as little kits. they range from about 200 grit to 100,000 grit"
..... As I write these lines, I pause for thought and believe that this procedure is vastly unlikely to succeed, but well, it may be that someone has tried it, and either failed or succeeded, I would like to know what you can recommend.
Thank you.

[Scarodactyl]

Cerium is a chemical polishing agent, so how 'fine' it is isn't so important. Ideally it should give results better than diamond paste in instancez where it works (odd to find a faceter who would prefer diamond for polishing silicates, but it gets fiddly and they do all have their own methods). Not so sure how well the flowing mechanism has really checked out, but it is a complicated and fraught topic and I'm not an expert. As to how it will affect lens geometry, I have found it to be surprisingly aggressive when polishing cabochons of some species (particularly feldspars) so it may have a greater effect than you'd expect.

[MichaelG.]

Rather than trying to polish-out deep scratches [which seems sure to degrade the figure of the lens] you could try filling them with black paint. ... This works well with vintage camera lenses, so it should be effective on an eyepiece : The black removes the disturbing highlights, at the expense of a very small reduction in effective aperture.

MichaelG.

[Sabatini]

Cerium is a chemical polishing agent, so how 'fine' it is isn't so important. Ideally it should give results better than diamond paste in instancez where it works (odd to find a faceter who would prefer diamond for polishing silicates, but it gets fiddly and they do all have their own methods). Not so sure how well the flowing mechanism has really checked out, but it is a complicated and fraught topic and I'm not an expert. As to how it will affect lens geometry, I have found it to be surprisingly aggressive when polishing cabochons of some species (particularly feldspars) so it may have a greater effect than you'd expect.

Thanks for your point of view, I find your recommendation more like a warning, logical given this case, but I find it difficult not to damage it more than to improve it... I will try with cerium, and I will also go to a jeweler and start to investigate better. I will do some tests before, in an eyepiece that has seen better days. I hope to be able to comment on the results.

[Sabatini]

Rather than trying to polish-out deep scratches [which seems sure to degrade the figure of the lens] you could try filling them with black paint. ... This works well with vintage camera lenses, so it should be effective on an eyepiece : The black removes the disturbing highlights, at the expense of a very small reduction in effective aperture.

MichaelG.

MichaelG
Cordial greetings.
Your recommendation is interesting, and it's a safe choice. I will implement it as soon as possible.
Thank you

[apochronaut]

Try a non-permanent marker first. That way, if it is close enough to the plane of focus and visible, you can easily remove it.

You described the scratches as being on the front lens, which I understand to be the front surface of the bottom lens of the eyepiece, not the eyelens. Scratches on the front surface, depending on the eyepiece design, are usually quite close to the plane of focus. At any rate, if you can see the scratch when viewing, you are likely going to see a cover. Black paint works where the imperfection is well outside the focal plane.

[Sabatini]

Try a non-permanent marker first. That way, if it is close enough to the plane of focus and visible, you can easily remove it.

You described the scratches as being on the front lens, which I understand to be the front surface of the bottom lens of the eyepiece, not the eyelens. Scratches on the front surface, depending on the eyepiece design, are usually quite close to the plane of focus. At any rate, if you can see the scratch when viewing, you are likely going to see a cover. Black paint works where the imperfection is well outside the focal plane.

Aprochronaut.

Aprochronaut.
Thank you very much, I am always attentive to your intervention, and of course I have relied a lot in the past on your knowledge and good judgment.
The scratches are in the eyepiece on the eyelid
It looks like the black marker method isn't going to work very well.

[Scarodactyl]

What type of microscope is it, by the way? If you can find a compatible pair Chinese eyepieces can often give perfectly good results.

[PeteM]

Polishing, even if done well, will remove the lens coating.

+1 As noted above, depending upon your microscope, you might find that a pair of $25-30 Chinese eyepieces would prove more satisfactory?

[Sabatini]

Greetings.
The eyepieces are the Mitutoyo UWF10x30.
That's why I find it difficult to replace
Although it is not very noticeable at low magnifications, with the M plan apo 20x scratches are very noticeable

[Scarodactyl]

Oh yeah, that's not going to work then.
For the love of all that's good don't try to polish those. You can always sell them for a parcel of dough if they're not usable for your purpose.

[Sabatini]

Oh yeah, that's not going to work then.
For the love of all that's good don't try to polish those. You can always sell them for a parcel of dough if they're not usable for your purpose.

lol:
Thanks for your nice advice.
I appreciate it.
I wouldn't have dared to do it so lightly either.

[Microworldofgems]

If the top element is flat (I don’t have any experience with these eyepieces) I would suggest laminating a coverglass over the top element and using norland optical adhesive to bond the lens and glass together. You will of course need to cut a coverglass into a round disc to match the diameter of the lens. The adhesive will fill in the scratch, and match the refractive index of the glass and lens making the scratch invisible. Just a thought, but obviously won’t work on a curved surface.

[Sabatini]

Thank you very much for the interesting information and possible solution, I will keep it in mind. The eyepieces are concave.

[Sabatini]

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[Sabatini]

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