dismantling and rebuilding a cemented doublet

Subject: dismantling and rebuilding a cemented doublet
From: "Robin Leadbeater"
Date: 10/12/04 15:44 Romance Standard Time
Message-id:


Thanks Chris,

Just the information I need. All I need to do now is find a friendly
microscopist to give me a drop of balsam. (The sources I have found so far,
although not unduly expensive, are more than the cost of this surplus
optic!)

Robin
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Robin Leadbeater
54.75N 3.24W
http://www.leadbeaterhome.fsnet.co.uk/astro.htm
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Hi

If you go to your local hospital Path lab (Ask for the Chief or Senior Chief
medical scientist) explain what you want and I am sure you will be able to get
some DPX. from the Histology Department. This is the modern replacement (there
are others) for balsam cement. It is used for sticking coverslips on tissue
sections. It has the same refractive index as glass. The solvent used to be
Xylene but as this is considered now to be toxic there will be another suitable
solvent.

If you do get some, clean the lenses like Chris suggests and then with a clean
orange stick or match stick (or thin glass rod) place a moderate drop of the
DPX in the centre of the lower lens. If there are any bubbles in ther drop just
touch them with the rod and they will "pop". Now place the upper lens carefully
onto the drop, press gently to spread out the DPX a little and let gravity do
the rest. The layer of cement will travel slowly out to the edge of the lenses.
If you still get bubbles in between then you can "chase" them out with gentle
pressure on one side or the other of the top lens There is plenty of time to
rotate the components with respect to themselves if needed. If the original
drop of cement was sufficient then you should get a perfect cement job done. If
there was insufficient, and you should know within 10 mins or so, then you can
still separate the components and try again. If they are stuck then just
soaking them in Xylene (or the current solvent) for an hour or so will easily
separate them. Once cemented leave them for 24 hours minimum and preferably a
couple of days before you play with them.

Phil