Lens Cement

[RichardJack]

Hi,
Does anyone know the a trade name or supplier for lens cement?
I can do the repairs myself, however I suspect that different lens manufacturers might use different cements and the refractive index might be different.
Thoughts on this?
thanks,
Rick

 

[AgX]

There are several synthetic lens cements, at least based on two different structures.
Here is one manufacturer even offering an additive to adjust the refractive index:
https://www.optical-cement.com/cements/cements/cements.html

Not all "optical cements" seem apt for applying within imaging optics. Manufacturers use that term differently.

 

[shutterfinger]

https://www.edmundoptics.com/lab-production/adhesives/norland-optical-adhesives/

 

[RichardJack]

Thanks...this is a good start. Getting the refractive index wrong is the scary part. I need to do more research.
Rick

 

[Jon Goodman]

I might still have some Canadian Balsam. If you want to see a tutorial I wrote on this, you could look here: http://fotomozaic.ro/artikel.php?s=1&categ=0&idstory=412
Jon

 

[Patrick Robert James]

You should probably state what lens you are trying to fix.... If you have a lens that only has a bit of edge separation, you can use super light oil to make the lens usable, though that is dubious in the long run.

Jon's tutorial is excellent. When I recement elements I use machinist's V-blocks which is a very accurate way of doing it. I "bake" elements that have been cemented with balsam in the oven for a while which speeds up the process. Balsam melts around 300º IIRC so you can just use it straight if you want, but it is easier if it has a solvent in it. Instead of a Sharpie (which is dye) I use a Pigma archival brush pen which is a pigment ink, or you can also use Speedball Super Black Ink which is carbon black with shellac if you need to lay it on thick. you could make your own too if you wanted.

I think Canada Balsam is better than UV cement if you are just getting going. Canada Balsam also doesn't go bad, so it is cheaper to use, and it is easily reversible. You should try to match the refractive index of the original cement if you can find out that information. Good luck with that! Canada Balsam has a refractive index of 1.52, most UV cements have a refractive index of 1.54/55 IIRC, and cyanoacrylates have a lower refractive index than CB (I think?). I am not an optics expert and am just passing on info I have learned over the years, so I am not sure how big a difference it makes. Maybe someone can chime in on that.

Hope that helps you, or anyone else for that matter.

 

[Jon Goodman]

I think I mentioned it in the tutorial I posted to Fotomosaic.ro but you can also use common rosin (pine rosin) as a substitute for Canadian Balsam. It isn't quite as good and refractive indexes may not be available for all varieties, but some of the rosin out there is close to colorless. Once upon a time the Surplus Shed had some Canadian Balsam for sale, but I don't know if they still do. They were always fine people to deal with, though. As for the Sharpie...I just used that because it was handy. Along the way someone else told me they used India Ink mixed with gum arabic, but I never tried that. It makes sense. I mix gum arabic with ink so it won't feather on less expensive paper. As pointed out above, the reversibility of balsam is a very nice point.
Jon