Re: ATM Un-cementing Prisms

[Brian Nestel <blast@aloha.net>]

Jim Sapp wrote:
>      I have a large chunk of glass, removed from a military surplus device,
> that seems to be a beam splitter made of two prisms cemented together, and
> coated. I would like to separate these prisms to make a pair of star
> diagonals, but suspect that they are not held together with good ol' easily
> separated Canada balsam, but some other military-tuff stuff.
>      Anyone know the right trick?
Hi:
 You can check if it is balsam with a UV light, if glued with a plastic there 
will be little or no fluorescence, if it is balsam there will be a hazy 
white fluorescence. Sometimes elements glued with balsam can be hard to
separate if they are tightly glued together,
balsam will separate with heat, put the prisms in a oven and slowly raise
the temperature to 275-300f, when they have been sitting for a while try
seperating with a slight twist, or running a piece of fine strong wire
(piano wire)between them don't try to pry them apart, you may chip them, 
and of course wear heavy gloves, cool slowly, when cool, you can clean 
balsam residue with alcohol.
If glued with a thermo-plastic glue,  soak the assembly covered with acetone
in a closed glass container for a few days and try to separate by twisting
or running a piece of fine wire between them or dental floss.
you may have to soak and try to separate a few times. 
Quite a while back we used to get bunches of surplus optics and break them
up for components and there were some elements that were almost impossible
to separate.
-- 
Aloha   159 30 W, 21 55 N
Brian   Middle of the Pacific,
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