Collimation of stereo microscope

Collimation of stereo microscope

Postby JohnG » Fri Jan 30, 2009 9:19 pm

I confess to being a microscope nut. I don't collect them, though I have a few, but I do enjoy getting second-hand ones, cleaning them, making LED lights for them and using them. eBay has provided a few but there are often better bargains elsewhere.

Recently I bought some bits on eBay - a Wild stereo head, eyepieces and objective. When I unpacked the head, there was a shower of glass shards and an ominous rattling noise as the prisms rolled around inside their metal cover. Despite the serious damage to the prisms, I think it may be possible to resurrect the head. What I need to know is how to align (or collimate) the prisms before fixing them in place. Does anyone have detailed instructions for this procedure, please? I guess it varies a bit between instruments but several CMO stereos use a similar prism design so I thought it worth asking. Maybe I'm not the only microscope nut on here!

John
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Re: Collimation of stereo microscope

Postby davidharries » Thu Feb 05, 2009 11:40 am

Hello John,
I found the article "Collimating Low Power Stereo Optics" by Paul James on the Microscopy UK website (http://www.microscopy-uk.org.uk) very helpful when I cleaned and refixed the prisms in a Vickers stereo. The article is in the library section of the website - subheading microscope.
Hope this helps,
David
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Re: Collimation of stereo microscope

Postby JohnG » Mon Feb 09, 2009 11:12 pm

Hello David,

So there is another "microscope nut" on here!

Thanks for that reference. I've had a read and can see that the method looks good. Paul was lucky in that his prisms had clamps that he could release for adjustment. Mine are or, rather, were cemented in place. (Now wedged with Blu-Tack). Maybe I could fashion some clamps as I don't fancy my chances of getting it right first time. Blu-Tack may hold in winter but allow the prisms to move when things warm up a bit!

I have also been told of another method, which I have tried with some success, though the alignment isn't perfect. It works with a zoom microscope. Focus on a target and zoom in and out. Adjust prisms so that the centre point stays still as one zooms. My centre point shifts by 0.75 mm (at target) now and I've stopped there rather than carry on and make things worse! My brain has no difficulty making a stereo image out of what I see.

All the best and thanks again,
John
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