Introduction: Glass Polishing for Special Lenses

Picture of Glass Polishing for Special Lenses

Polishing a lens is not easy, but not impossible.

Step 1: Polishing Glass: Cerium-oxide

Picture of Polishing Glass: Cerium-oxide

If you have on optical surface, the best solution to polish it is to use a mixture of water andcerium oxide (prepared special for this purpose). Or, you can purchase for example the 3M 60150 material. This is a water based suspention, which you have to use with a clean smooth tool, made for example of wool. OK, this works for plain or uniform surfaces - but what to do, when you have a special shaped lens, which, to make it even more interesting, is made of plastic and not of glass. This is a problem, because if you use a formless piece of wool, you can definitely modify the lenses shape.

So we need a perfect negative of the final lens. The problem is more complicated, when the lens is non-spherical like in my case....

During the polishing you need to work with a concentric and radial movement - so I decided to make the negative form on a small grinding tool, which can be fixed in the power tools used by modelling.

Step 2: Making a PERFECT Negative

Picture of Making a PERFECT Negative

I used a 2 component glue named Poxipol, made in Uruguay (!!!). To protect the lens, I covered it with a piece od nylon bag. Pulling it with a certain force covers perfect the lens, and gives a very thin separating layer.

I applied the glue on the surface of the nylon cover, and I positioned the grinding stone perfectly vertical.

After 10 minutes (Poxipol is a wonder...) I just separated the hardened glue - and i have got the negative.

Step 3: Mounting of the Smooth Layer

Picture of Mounting of the Smooth Layer

As a smooth material I used an optical tissue, fixed on it just with some tape. And after 15 minutes of polishing in a plastic box I was like a white pig - but the lens has got back it's original form and shiny surface.

(Just to understand why did I have to do this: unfortunately I whiped this lens whith some methanol during cleaning. It was a fault: the lens has been damaged immediately.)

Comments

thanks for sharing! How did you position the grinding stone to be perfectly vertical while the glue sets up?

there is no need of that. just positioned visually.

if should be more precise, I would use the drilling machine in a stand.

guillaume.sala.5 (author)2017-03-01

just wonderful!

Thank you for sharing this!!!

About This Instructable

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Bio: Born in 1965, engineer. Living in Hungary. Spoken languages: hungarian, romanian, english, german. interested in repairing Canon Lens and DSLR, photography, machining (turning, milling)
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