Cleaning Glued Optics Question

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chhejr
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Joined: Thu Jan 07, 2021 6:05 pm

Cleaning Glued Optics Question

#1 Post by chhejr » Sat Jun 25, 2022 6:21 pm

I have this optics piece that is just after the eyepiece in a Nikon SMZ-10 stereo microscope. I am trying to clean it as I see a significant smudge in it. It consists of three triangular prisms glued together.

The smudge looks like it is between two of the glued together prisms. So I assume that to clean this I would need to unglue them, clean the mating surface, and reglue them together.

My question is, what's the proper way to do this? What do I use to unglue these? What should I use to clean them? And, What glue should I use to reattach them? Are there special clamps I would need to use to glue them together?

BramHuntingNematodes
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Location: Georgia, USA

Re: Cleaning Glued Optics Question

#2 Post by BramHuntingNematodes » Sat Jun 25, 2022 6:54 pm

Norland has uv activated optical cement although what you trying to do is no mean feat and may well require hashing up some wooden jigs
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

chhejr
Posts: 14
Joined: Thu Jan 07, 2021 6:05 pm

Re: Cleaning Glued Optics Question

#3 Post by chhejr » Sun Jun 26, 2022 10:25 pm

Ok, but how do i dissolve the glue to remove the two prisms? What solvent do I use?

apochronaut
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Re: Cleaning Glued Optics Question

#4 Post by apochronaut » Mon Jun 27, 2022 1:22 am

You don't know what they used for a cement, so you have to experiment with solvents. Chances are the more common alcohols won't work but acetone will more likely do it and it is the easiest stronger solvent to access. If not move up to Butanone.

I have solved such delaminations in lens groups with heat alone ( using a dry chamber inside a boiling water bath: so around 200° F.) but in some instances that did not work. Perhaps, I didn't leave the lens long enough or the temperature was not high enough. I have been afraid to use a dry oven due to the possibility of too rapid cooling and fracture. That would be a larger risk with a prism set. That however, is to heal a delamination, not separate and clean one.

apochronaut
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Re: Cleaning Glued Optics Question

#5 Post by apochronaut » Mon Jun 27, 2022 2:04 pm

The first synthetic cements were developed due to military interest where resiience to vibration , sudden shock and extreme temperature variations were very important. They were thermoset and the cured cement had a degree of pliability that balsam did not have.
Repairing delaminations under military conditions also became important. Theoretically, a thermoset joint can be delaminated within a certain time frame at the correct temperature but those parameters were difficult to obtain and ensure, so patented devices were invented in order to delaminate quickly. Final cleanup was with acetone.
So, why not de-laminate with acetone? The only answers I can think of is that acetone alone takes a long time and is messy. Thermal de-lamination , leaves the elements quite clean, requiring little additional cleaning with acetone.

A number of years ago I got it in mind to buy a Balplan 12.5X Flat Field Apochromat from a former B & L dealer that had a few of them. They were all de-laminated but the dealer said that if he had the time he could fix them. When I asked how, he said : heat.

The devices made for the U.S. military bring the optical complex up to about 450° F.

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