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
| Free forum by Nabble | Edit this page |