Reichert Polyvar Microscope

[apochronaut]

Stored in a shed or garage, storage or unheated warehouse, the temperature can fall to between 0 and 10 F. during winters in the northeast and across the midwest as far as Montana. Once chilled down, unheated storage facilities warm slowly, when the weather turns, and with a warming atmosphere and rising humidity, cold, dense materials like metal and glass become condensation traps.

[MWK]

This is probably what happened. The microscope was stored in a cold garage when I picked it up. It's a bit of a shame...

[BramHuntingNematodes]

Not too much of a shame as I am sure you will perfect re-lamination techniques, restoring the scope to even better than new and able to pass your experiences along.

[MWK]

Not too much of a shame as I am sure you will perfect re-lamination techniques, restoring the scope to even better than new and able to pass your experiences along.

Thanks for the encouragement! I will try my best.

[MWK]

Does anyone have a small amount of Norland 61 Optical Adhesive they could send me for the test? Seeing if I can avoid spending $70-80CAD (cost + shipping + exchange) on a full bottle just to test whether or not it will work. It's worth a shot!

[Hobbyst46]

Does anyone have a small amount of Norland 61 Optical Adhesive they could send me for the test? Seeing if I can avoid spending $70-80CAD (cost + shipping + exchange) on a full bottle just to test whether or not it will work. It's worth a shot!

Sorry that I cannot help with that; a recent thread claims that small amounts of NOA61 might cost less:
https://www.cloudynights.com/topic/6610 ... nt-a-lens/
A typical drop of water has a volume of ~0.05ml. A typical drop of the adhesive is likely smaller, say 0.03-0.04ml. To glue one surface to another one needs a small amount, perhaps 2-3 drops at the most, so perhaps a 1g quantity of the NOA61 (that would be ~0.8ml, or ~20 drops) might suffice for your project ? I think Norland supplies the stuff in 1g packages as well.

[apochronaut]

Since you have cleaned the old adhesive from the surfaces completely, I wonder why it might be necessary to use such an expensive product? Would balsam not do just as well? It was used for over a century, and presumably the only reason for it's replacement with synthetic resins was that de-laminations with balsam occurred. In hindsight, the synthetics, at least the earlier ones, don't appear to be any better in that regard and there are in fact lots of examples of exceptionally high N.A. objectives, condensers and their supporting prisms of great age, that are still in pristine condition. I have some cemented prisms in binocular heads sitting 10 feet from me that are 100 years old and capable of transmitting the information from the 1.4 N.A. objectives fitted below them , flawlessly.

[MWK]

I'm open to using either UV cured cement or Canada Balsam, but I can't seem to be able to find Canada Balsam anywhere.

[PeteM]

MWK - I checked and my parts Polyvar doesn't have good binocular head prisms.

One suggestion, if cementing yours back together doesn't work. It looks like the entire head is held by 3 screws, much like many other heads. There's some chance you could adapt another infinity head, such as the ones used for Nikon Optiphot 150/200 scopes or Leica DM?? Those two brands are set up for a 200mm infinity tube lens and I'd guess your Reichert/Leica is as well. I've seen both those other infinity heads, with damage elsewere to the head for well under $100. Assuming the optics can be matched, you'd just have to drill and tap 3 holes -- or 6 holes if you need to make an intermediate plate to match bolt (screw) circles.

If you know someone with another set of binoculars to try, it would be pretty quick work to try them out (undo 3 screws, hold them in place) and see if you're getting a good image. And if you needed a tube lens, yours is likely still good.

[MWK]

MWK - I checked and my parts Polyvar doesn't have good binocular head prisms.

One suggestion, if cementing yours back together doesn't work. It looks like the entire head is held by 3 screws, much like many other heads. There's some chance you could adapt another infinity head, such as the ones used for Nikon Optiphot 150/200 scopes or Leica DM?? Those two brands are set up for a 200mm infinity tube lens and I'd guess your Reichert/Leica is as well. I've seen both those other infinity heads, with damage elsewere to the head for well under $100. Assuming the optics can be matched, you'd just have to drill and tap 3 holes -- or 6 holes if you need to make an intermediate plate to match bolt (screw) circles.

If you know someone with another set of binoculars to try, it would be pretty quick work to try them out (undo 3 screws, hold them in place) and see if you're getting a good image. And if you needed a tube lens, yours is likely still good.

That's interesting. I might try that as my last resort. I would rather have the original binoculars though.

[MichaelG.]

I will try Ethanol.

The cement bits are pretty hard and crack when I bend them. The other bits (also yellow, look like tear drops) are very flexible, almost like silicone. The prism was attached to the housing with these little pieces.

EDIT: I tried Ethanol and Acetone and the bits don't dissolve in it.

This may be of interest:

A beam splitter is the crucial part of most interferometers.In its most common form, a cube, it is made from two triangular glass prisms which are glued together at their base using polyester, epoxy, or urethane-based adhesives. The thickness of the resin layer is adjusted such that half of the light incident through one port is reflected and the other half is transmitted due to frustrated total internal reflection.

Ref. http://www.hhv.in/categories/thin-films ... -splitters

MichaelG.

[MWK]

Thanks for that! I'll take a look at it.

So, since the prism I have right now is sacrificial and for experimentation purposes only, I decided to see if I could fully detach all lenses from the prism. You'll see in the previous photos that I managed to separate the angled lens with boiling water. The cement didn't dissolve but just separated.

I decided to experiment with hot and cold water (expansion and contraction). I've read that this is quite dangerous to attempt on lenses since they can crack, but luckily in my case it worked. Heating up the entire prism with warm/hot water (not boiling) then only running cold (not freezing) water on one side, you can basically cause delamination and ultimately separate the two pieces of glass. It requires multiple attempts of hot / cold but it will start to delaminate and separate. I now have all pieces of glass separated so I can test cementing them back together. I don't like to test things a single time so if I can successfully glue all four pieces of glass with good results, then I'll be confident enough to work on my main binocular tube prism. Also, I guess it justifies spending +$80 CAD on buying this UV Cement.

[apochronaut]

I think doing a test run is a good idea.
Without knowing the actual n of the prism glass used, matching the cement to it might be tricky. There is the technical issue of FTIR( frustrated total internal reflection), which is caused by the cement n being sufficiently higher than the forward prism n and was in fact the method used to manufacture earlier beamsplitters. Presumably, yours has a coating on the hypotenuse of the forward prism but may also rely on FTIR.

[MWK]

There's a coating on the prism. I tested quickly just with water. With water I can see how the angle and position of the two pieces affect the line of sight. I'm not sure how differently the cement will affect the optics but I'm assuming Norland 61 will be fine?

[Hobbyst46]

There's a coating on the prism. I tested quickly just with water. With water I can see how the angle and position of the two pieces affect the line of sight. I'm not sure how differently the cement will affect the optics but I'm assuming Norland 61 will be fine?

Why not consult it with Norland ? Their tech support is great even if you are not a buyer.

[apochronaut]

Possible glass types used in prisms.

Glass Formula Refractive Index
Fluorite 1.433
Fused Quartz 1.4585
BK 7 1.5168
Light Barium Crown 1.5411
BK 4 1.5688
Light Flint 1.5725
Dense Flint Glass 1.620
Extra Dense Flint Glass 1.6725
Very Dense Flint Glass 1.728

NOA 65 ( n = 1.52) is noted as being particularly strain free, something not noted for NOA 61 ( n= 1.56) , despite it's high recommendation for many optical applications. NOA 65 is also noted as being not as hard as NOA 61 , which can be polished and ground after curing.

[MWK]

Possible glass types used in prisms.

Glass Formula Refractive Index
Fluorite 1.433
Fused Quartz 1.4585
BK 7 1.5168
Light Barium Crown 1.5411
BK 4 1.5688
Light Flint 1.5725
Dense Flint Glass 1.620
Extra Dense Flint Glass 1.6725
Very Dense Flint Glass 1.728

NOA 65 ( n = 1.52) is noted as being particularly strain free, something not noted for NOA 61 ( n= 1.56) , despite it's high recommendation for many optical applications. NOA 65 is also noted as being not as hard as NOA 61 , which can be polished and ground after curing.

No idea. What's my best bet? The cement I removed from the prisms is pretty flexible, so perhaps it is not that hard. NOA 65?

[Scarodactyl]

Maybe this is wrong, but can't RI be measured with a microscope? I have seen this recommended for gem usage but haven't tried it. The stated procedure was to measure the thickness of the subject, then measure the travel of the microscope head between focusing on the top of the subject and focusing through it to the bottom. The ratio should give the RI. I need to chase down a proper citation for this. That said for something this thick the wd required would suggest a stereo, and I am not sure what the angle would do to that measurement (though the standard in gem circles is a stereo so who knows).

[MWK]

I was told by Norland that 83H might actually be a better alternative because it can be heat cured. The issue with curing a prism is that UV light doesn't necessarily reach the bond line due to the nature of the prism. For that reason, a heat activated adhesive is a more sure way to cement both glasses together. If the UV light is shown on both sides of the prism, I think I may be ok though.

https://www.norlandprod.com/adhesives/NOA%2083H.html

[apochronaut]

That may sound like your choice then, as long as all the other factors are a fit.

[MWK]

I might end up just getting the NOA 61. I'm worried about having to heat up and cool the prism. That's basically what probably got me the delamination in the first place.

[wporter]

For curing Norland 61, I use a UV flashlight for the initial set, at a few different angles for 20 min-1 hour total exposure. I then lay it out in the sun for a couple of days, usually placing the lens or prism on top of a mirror or white cardboard. Never had any failures, knock on wood.

[microb]

Do you have to put the resin in a vacuum to remove possible bubbles?

[Hobbyst46]

If a UV flashlight is not available, a potential alternative is a home light tube - a "dark light" (or "black light") thin fluorescent-bulb-like UV tube. It glows violet, and is used to render "atmosphere" to youth at home. Not a collimated focused beam, yet it works if the surfaces are laid within a few cm from the tube and parallel to it. I use black cardboard shields to prevent looking directly at the light. Worked for me in curing NOA61 as slide-coverslip mountant layer. I just left it there for an hour or so.
Yet another possibility, though more expensive, is a manicurist finger-nail illuminating box. Some nail polish gels are cured with UV.

[wporter]

"Do you have to put the resin in a vacuum to remove possible bubbles?"

No, definitely not. Although this depends on not having any entrained bubbles to begin with.

Bubbles will arise from shaking the Norland bottle before using, or from applying in a manner that adds bubbles as you apply a drop to one surface; both these errors are easy to avoid, especially if you practice applying a drop without having the top of the drop exhibiting tiny bubbles. But if you end up with just one or more bubbles on top, you may have success poking it or them with a needle, to pop them. The odd bubble off to the side after squishing the two optical surfaces together may be moved out sideways with further squishing. You may want to practice this whole cementing exercise by gluing a couple of slides or cover glasses together.

Regardless, if the bubble ends up inbetween the two optical surfaces that you are gluing together, despite your best efforts, you can still start over by cleaning off everything (with acetone, I believe) and giving it another try with fresh adhesive. (Assuming you aren't doing this in direct sunlight or other UV source that may have hardened up the cement.)

[MWK]

"Do you have to put the resin in a vacuum to remove possible bubbles?"

No, definitely not. Although this depends on not having any entrained bubbles to begin with.

Bubbles will arise from shaking the Norland bottle before using, or from applying in a manner that adds bubbles as you apply a drop to one surface; both these errors are easy to avoid, especially if you practice applying a drop without having the top of the drop exhibiting tiny bubbles. But if you end up with just one or more bubbles on top, you may have success poking it or them with a needle, to pop them. The odd bubble off to the side after squishing the two optical surfaces together may be moved out sideways with further squishing. You may want to practice this whole cementing exercise by gluing a couple of slides or cover glasses together.

Regardless, if the bubble ends up inbetween the two optical surfaces that you are gluing together, despite your best efforts, you can still start over by cleaning off everything (with acetone, I believe) and giving it another try with fresh adhesive. (Assuming you aren't doing this in direct sunlight or other UV source that may have hardened up the cement.)

Thanks for the pointers! I'm going to try to get one of those 365nm UV flashlights from Amazon. Just trying to avoid the one's that are falsely advertised as such.

[microb]

Bubbles will arise from shaking the Norland bottle before using, or from applying in a manner that adds bubbles as you apply a drop to one surface; both these errors are easy to avoid, especially if you practice applying a drop without having the top of the drop exhibiting tiny bubbles. But if you end up with just one or more bubbles on top, you may have success poking it or them with a needle, to pop them. The odd bubble off to the side after squishing the two optical surfaces together may be moved out sideways with further squishing. You may want to practice this whole cementing exercise by gluing a couple of slides or cover glasses together.

Oh, so this isn't a two tube resin mix then. Stirring the two halves together requires a vacuum for good results.

[wporter]

It's a one-part, UV-hardening liquid. Relative to epoxies or other messy or problematic adhesives like super glues, very nice stuff to work with. For those who are using it to repair joined prism assemblies, stacked lenses, or other complex arrangements, some kind of jig or other hold-it-all-in-place support fixture is recommended prior to the UV exposure. E.g., for stacked lens groups, v-blocks are often used to hold the individual lenses in axial alignment, with maybe a small weight on the top lens to apply a bit of pressure to the inter-lens cement films (which obviously you don't want too thick).

Unless you're a professional, a 1 oz (28 g) bottle would last a lifetime. At one time, I considered buying a fresh bottle and divvying it up into 2 to 5 ml vials for the group here. May still do this, but can't at the moment, am in the middle of a move.

[a.kat]

Thanks for the pointers! I'm going to try to get one of those 365nm UV flashlights from Amazon. Just trying to avoid the one's that are falsely advertised as such.

There is a very good cheap UV flashlight with really strong output on Aliexpress. There are versions with Nichia and LG UV leds. I can post a link if it's ok with the forum rules.

[MWK]

Send me a PM?