Re: High NA darkfield condenser
- From: Aaron <nghy@xxxxxxxxxxx>
- Date: 10 Feb 2006 21:35:03 -0600
Hello,
As Gregor pointed out a typical high NA darkfield condenser of the
cardiod or parabaloid type needs to be inclose contact with the slide
and the slide must be thin, no more than 1.1mm.
However the darkfield effect can be achieved in other ways. Brian
Bracegirdle in his book PhotoMACROgraphy shows several setups for dark
field macro photography that could be adapted for an inverted scope.
Also I have a transmitted light base designed by Diagnostic
Instruments which uses a Fiber optic ringlight with the center portion
filled with a black velvet stop to create a darkfield effect for
stereo microscopes. The fiber optic ring is just slightly larger than
the field for the dish. I have this tranmitted light base installed
under a Leica M420 Macroscope. It provides excellent darkfield and
the principle would work with an inverted scope.. .
In essence darkfield lighting is created by directing strong focused
beams of light at the specimen at very oblique angles such that the
ONLY light entering the objective is that refelcted by the specimen.
If you have a strong fiber optic light source, try shining the light
at very low angles of incidence at the culture dish. place a dark non
reflective cover over the top of the dish so that the overhead
lighting does not shine on the dish. You can experiment with light
coming in at the sides of the dish. Two light pipes should be enough.
A ring light would be more semetrical. If you direct the light from
just one side at a slightly larger angle of attack you can generate
oblique lighting. Bothe the oblique and the darkfield are good ways
to reveal water white (uncolored) specimen.
Aaron
On Fri, 10 Feb 2006 18:32:26 +0200, "Klas Lindfors"
<klas.lindfors@xxxxxx> wrote:
Dear all,.
Maybe someone in the group can help me find a high NA (>1.3) darkfield
condenser for my Nikon TE-2000 inverted microscope. Nikon does not have any
DF condensers at all for this microscope but to me it does not seem
(naively?) to be too difficult to adapt a condenser from another
manufacturer to the system. Image quality is irrelevant, the DF is only
there to detect point like scatterers. My question is: does someone in the
group have experience/ideas on how to most conveniently do DF microscopy on
a TE-2000? Any suggestions and ideas are greatly appreciated!
Klas Lindfors
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