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FrozenGate by Avery

Method for removing scratches from (roughly 1 inch) lens?

rhd

rhd

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I have a glass lens that is irreplaceable, and I need to remove scratches from it. It's a rather large (roughly 30mm) convex glass lens, and it has scratches / wear that baking soda / toothpaste won't take out.

I have even tried 2,000 grit sandpaper without luck. It's not so much that any individual scratch is large, but rather that the glass has become "dull" from lots of scratches all over the place.

There is no AR coating to worry about. However, finding a new lens won't work in this situation.

Any thoughts or suggestions ?
 
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I think it's actually acrylic he's using there.

Unfortunately, I never have any luck engaging anyone via PM on CPF - I think because I have 3 posts to my name there.
 
I'd tell you to spray it with clearcoat and sand it with that 2000 grit paper, but that would have tiny density change on the surface and probably cause diffraction.

Out of curiosity, why is this lens so irreplaceable?

-Trevor
 
What you're asking is impossible.

You want to take emptiness out of a solid object. You can only do that in 3D modeling software ;)

If you polish the glass down below the lowest point of the scratch, you have changed it's thickness and hence, focal point. Which isn't too bad if you polished it PERFECTLY symmetrical.

Which is again, next to impossible to DIY.

Also, what Trevor said. Why is this lens so unique?
 
Eudaimonium said:
What you're asking is impossible.

You want to take emptiness out of a solid object. You can only do that in 3D modeling software ;)

If you polish the glass down below the lowest point of the scratch, you have changed it's thickness and hence, focal point. Which isn't too bad if you polished it PERFECTLY symmetrical.

Which is again, next to impossible to DIY.

Also, what Trevor said. Why is this lens so unique?
Click to expand...


Good point....

Jerry
 
there is a diamond paste out there that should help you. mold makers use it to remove scratches of of high polished stainless steel molds. but like euda said. it will change your glass.

michael.
 
Try finding a (relatively local) astronomy club where members make thier own mirrors and lenses. They might be able to 'closely' duplicate the optics on new glass. Alternatively, optometry school, or local optometrist, might be able to do likewise.
 
The lens is a component of a 50+ year old antique device. I *could* try to replace it, but that would destroy some of the charm.

The next obvious concern is that you generally lose value when you refinish an antique, which might be true here, but this isn't a value issue, its a functional one.

That said, loosing some of the glass, even if it somewhat alters the focal point. Is probably ok here. How might I best go about this?
 
rhd said:
The lens is a component of a 50+ year old antique device. I *could* try to replace it, but that would destroy some of the charm.

The next obvious concern is that you generally lose value when you refinish an antique, which might be true here, but this isn't a value issue, its a functional one.

That said, loosing some of the glass, even if it somewhat alters the focal point. Is probably ok here. How might I best go about this?
Click to expand...

OK.... so you peaked my interest... what is this unique 50+ year old
antique device that uses a 30mm unique lens...:thinking:

Jerry
 
rhd my dad has some disks that are used to polish the end of a fibber-optic cable it polishes glass to a perfect shine but it may deform the lens how precise does it need to be need it.
there a couple of inches in diameter


this is it.
Platt.com: 3M - 6192A254X2D5, Lapping Film/Polishing Paper, Fiber Optic Termination Kits & Accessories, Datacomm Installation Tools & Supplies, Tools, Testing, Meters
I believe this is the same stuff only in large square sheets AT&T TYPE B POLISHING PAPER 25 SHEETS 105433167 FIBER on eBay!
 
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I'm guessing some lamp or projector, now I'm curious too.
Well I guess you could polish out the scratches with lots of patience,
but I don't know what compound to use.
I know there is stuff like that to remove scratches from car windshields.
 
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