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Hi Ainhoa,

I suggest using filter cubes with standard single pass exciter and 
long pass dichroic and emission filter. If your current cubes are 
old, by all means buy new ones (especially ones with light dumps and 
"hardcoated"). This way you can do what you always do by eye. The 
Axioplan is a popular microscope and there are probably others near 
you that you could borrow filter cubes to test. Your local rep can 
also loan you some.

If you want further excitation blocking, you could add an excitation 
polarizer or buy a cube with a sandwiched exciter+polarizer). The 
standard VariSpec LCTF acts as a linear polarizer (analyzer in DIC 
parlance, given its location on the scope, rotate the VariSpec to 
achieve maximum extinction), though the filter cube and/or objective 
lens or other optical elements could cause some depolarization 
(especially very high NA lenses).

If you want to go for something really clever, check out Sawano and 
Miyawaki 2002 Biophys J 82: 1076 for clever vs standard 
(http://www.biophysj.org/cgi/reprint/82/2/1076).

Enjoy,

George
p.s. I vaguely recall that the VariSpec worked ok as the DIC 
analyzer. Make sure it (or the transmission polarizer) are rotated 
for max extinction. Leave the prisms in place and switch between 
transmitted and fluorescence.


At 07:30 AM 5/21/2007, you wrote:
>Search the CONFOCAL archive at
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
>We have bought a Varispec tunable filter for our Zeiss Axioplan 2 Imaging
>microscope. We need now to find out a reasonable configuration for the
>excitation part. We are considering to buy a number of excitation filters
>covering the full Varispec spectrum.
>For the mirror part, we wonder if there exists a polychroic commercial
>mirror that suits well for the problem at hand or we have to buy a different
>dichroic for each excitation filter. Could you help us?
>What would you recommend?
>Thanks a lot in advance.
>Best regards,
>Ainhoa Urbiola
>--






George McNamara, Ph.D.
University of Miami School of Medicine
Image Core
Miami, FL 33010
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