This will vary from objective to
objective. I use a calibration slide (stage
micrometer) and measure the spacing at the
edges and at the centre.
Do remember that in a confocal
non-linearity of the scan is also a
possibility, so it’s best to check
in widefield. Also, the coupling lenses
for your camera may not be perfect, so if
you get strange results check
them against an eyepiece micrometer.
For flatness (or otherwise) of field a
very good sample is a coverslip
very lightly smoked over a match-flame. Make a few scratches to
give
some coarse detail for easy location of
the focal plane. Mount it on a
slide with a drop of oil. Then check
the focal shift between the centre
and the edge. This sample is also
very good for showing up chromatic
aberration.
You will probably be surprised by what you
see when you do these
tests!
Guy
Optical Imaging Techniques in Cell Biology
by
http://www.guycox.com/optical.htm
______________________________________________
Associate Professor
Electron Microscope Unit,
Phone +61 2 9351 3176 Fax +61 2 9351 7682
Mobile 0413 281 861
______________________________________________
From:
Sent: Tuesday, 2 December 2008
5:27 PM
To:
[hidden email]
Subject: Flat field correction of
objectives
Hey everybody,
I was wondering if there is a simple answer to this question. I am looking for
data regarding the quality and/or efficacy of optical abberation corrections in
various types of miroscope objectives. Particularly, I am interested in the
linearity of the magnification from the central optical axis to the extremes of
the field of view of objectives as well as flat field corrections. Obviously
this will vary between different objective classes and wavelengths, but I
can’t seem to find any hard data on magnification distortions across a
field of view for any objectives.
Does anyone know of a good source for these types of data, or of an approved
method of measuring these distortions, if any?
Thanks
nick
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