Help on Decontacted Etalon

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Geremia Forino
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Help on Decontacted Etalon

Post by Geremia Forino »

Hello to all,

i need your help on this LS35T decontacted etalon, the spacer seem to be well attached to one of the two surfaces.My question is, what can I use to clean them (spacer and etalon) and what kind of glue should be used, also, and this is the most important, I need any kind of recommendation that can take me to the success of this repair
:bow


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Re: Help on Decontacted Etalon

Post by swisswalter »

Hi Geremia

I'm sorry for you. Was that an accident ? Have you contacted LUNT ? Where are you living ?


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Re: Help on Decontacted Etalon

Post by marktownley »

You could try Oliver at Beloptik, he recontacts etalons...


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Re: Help on Decontacted Etalon

Post by Geremia Forino »

Hello Walter, it is bomm, fallen on the ground, I'm living at south of Italy, Naples. I read about that you're an expert on this :D :D :D

@marktownley
I would like to see if I can save that amount, 250 euro for us Italians are a lot of pennies


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Re: Help on Decontacted Etalon

Post by Merlin66 »

Geremia,
I assume you have two of the small spacers still in place on one etalon plate and the other spacer still on the second etalon plate?????
There's no glue involved. It requires full "optical" contact to be made between the spacers and the etalon plates.
The optical surfaces must be clean - really really clean - chemical isopropyl alcohol or chemical acetone can be used.
When the surfaces/ spacers are perfectly clean they can be laid back against each other - note the alignment marks in your photo.
Use a flat firm base with a layer of tissue...
Using a razor blade, dip it in distilled water and very gently use the sharp edge to place a LITTLE onto the spacers by easing the razor blade into the side of the gap. Not too much! A VERY small amount is required to wet the spacer surface.
Press the plates together - if you're very very lucky you'll see the spacers make good contact.... Otherwise, gently tap the top etalon plate above the spacer(s) with the end of a plastic rod (to prevent damage), if everything goes to plan they spacers as viewed from the front, should "disappear" as they make optical contact....
Let the assembly dry out completely then re-assemble in the scope.
I make no assurances to you, this is done absolutely at your own risk....


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Re: Help on Decontacted Etalon

Post by Geremia Forino »

Thanks Merlin, i will try tomorrow early in the morning why today, I had much coffee :D


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Re: Help on Decontacted Etalon

Post by swisswalter »

Hi Geremia


good luck on the fix. You could always contact Oliver at beloptik


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Re: Help on Decontacted Etalon

Post by fjabet »

I did it a couple of times on Coronado. As Merlin mentioned just clean up thoroughtly the spacers with aceton (better than Alcohol), align, and firmly recontact until you hear the snap sound of the molecular bonding.
BUT if the spacers are surrounded by glass little pieces as I saw on the couple of Lunt etalon I had, it may be very very difficult.
Coronado's are very clean when compared with Lunts.

Here is a of the shelves Lunt LS50Fha with very poor molecular bonding and glass shreds sourrounding them :evil:

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Re: Help on Decontacted Etalon

Post by Geremia Forino »

Game Over, I lost the spacers :oops:

everything was ready, my desk looked like a nuclear laboratory, acetone, distilled water, razor blade and those of latex, but.....missing the most 'important, SPACERS :mad: :mad: :mad:


now :?:


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Re: Help on Decontacted Etalon

Post by swisswalter »

Hi Geremia


ohhhhh noooooooooooo.


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Re: Help on Decontacted Etalon

Post by marktownley »

A claim on your insurance?


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Re: Help on Decontacted Etalon

Post by Geremia Forino »

I have everything ready to be shipped to Beloptik, I think this is the best solution,

thanks anyway for your valuable advice
Geremia


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Re: Help on Decontacted Etalon

Post by swisswalter »

Hi Geremia

good luck


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
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Re: Help on Decontacted Etalon

Post by Geremia Forino »

Thanks Walter


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Re: Help on Decontacted Etalon

Post by Bob Yoesle »

I don't know if Oliver can supply the spacers independent of what came with the filter. Without all the spacers you might be looking at having to get a new etalon. Or you might have to send it back to Lunt tho have all the spacers replaced and re-contacted. Spacer thickness and uniformity requires that they all come from the same area of the spacer "blank."


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Re: Help on Decontacted Etalon

Post by Geremia Forino »

This was my concern to, but, is it so difficult to find a something to substitute mica ?

very thin and pure microscope Slides ?


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Re: Help on Decontacted Etalon

Post by Bob Yoesle »

Etalon spacers need to be made from a very low expansion material such as pure fused silica, quartz, Zerodur, etc. Then they need to be polished flat to about 100 lambda on both sides, with no wedge. The thickness needs to be controlled based on the design of the filter and its coatings to achieve the proper gap spacing. Then they need to be broken off the same area of the finished spacer disc to ensure etalon plate parallelism and uniformity...


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Re: Help on Decontacted Etalon

Post by Geremia Forino »

Bob, thanks for your clarification


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Re: Help on Decontacted Etalon

Post by Geremia Forino »

Good good news from Oliver beloptik,

seems that he is able to fix it even with a lost spacer, hope to show you a nice first light as soon as I get it back


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Re: Help on Decontacted Etalon

Post by swisswalter »

Hi Geremia

great news. I'm happy for you


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Re: Help on Decontacted Etalon

Post by marktownley »

Good stuff, let us know how first light goes...


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Re: Help on Decontacted Etalon

Post by Geremia Forino »

The miracles as been done by Oliver from beloptik :D ,just with the remaining 3 spacers.

now the next steep, dual stack it with the Daystar 0.5A. Today i received from my friend CNC Lathe Operator, the box to fit the ls35. On the front is a 140mm ERF and Powermate 4X that reach the f/30 on a TEC140, now I have just to wait a decent ray of sun ;)

Any suggestion or recommendation ?
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Re: Help on Decontacted Etalon

Post by swisswalter »

Hi Geremia

great news, looks very, very clean that recontacted etalon. That double stack setup looks fine too. I would have used a TZ4 instead of a powermate. Looking forward to the first light


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

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Re: Help on Decontacted Etalon

Post by marktownley »

Good news! That setup will work well :)


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