[Petwksp] false pleochroism in plane light

[Jodie Hayob]

Hi William,

      I have not noticed false pleochroism, but you mention 'teaching petrographic microscopes'.  I assume for student purposes therefore that you guys have purchased less expensive 'student' scopes?  We have Nikons primarily, and some Leitz scopes - but they are all research quality (about $7K a piece last time we ordered some).  We have 2 newer model Nikons, about 9 older model Nikons (which I actually like the best) and about 3-4 of the Leitz (which have a very yellowish light source that I don't like, but otherwise very good optics).  On what minerals have you observed this false pleochroism?  Cheers, Jodie


Jodie Hayob,
Professor of Geology
Dept. Environmental Science & Geology
University of Mary Washington
Fredericksburg, VA  22401
Phone:  540-654-1425
FAX:  540-654-1081
jhayob at umw.edu


>>> William Peck <WPeck at Mail.Colgate.Edu> 09/05/06 9:42 PM >>>
Hello all-
 
Apologies for cross-posting of this message.  I have a question for those of
you who have bought binocular teaching petrographic microscopes in the last
few years.  Recently we have noticed that the microscopes we have looked at
have some kind of pleochroism-like effect in minerals that should not
exhibit it. Sometimes this is minor but other times it is very noticeable.
 
We have seen this effect in Meiji and US Micro scopes from different
salespeople, and when shown the problem they have been able to minimize the
effect but not eliminate it. We have swapped around components and I think
the problem is perhaps introduced somewhere in the binocular head.

Is this something any of you have encountered?  It is very noticeable, and
I¹m surprised that our salespeople haven¹t had min/pet instructors from
other schools as frustrated as we are. Any thoughts/experiences would be
appreciated.
 
William


_______________________________________________
Petwksp mailing list
Petwksp at serc.carleton.edu 
http://serc.carleton.edu/mailman/listinfo/petwksp