Posted by
Johannes Helm on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Concentrating-bacteria-cells-for-microscope-visualization-tp6519025p7137850.html
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Dear Michael,
it possibly depends on the generation of objective.
I recall that, during the early 90s, when I was a PhD student at Aaslund's
and Carlsson's at Physics IV at KTH in Stockholm, we worked intensively on
UV CLSM techniques. We measured the axial chromatic aberrations of a large
number of lenses, including "exotic" objectives like Ealing mirror
objectives, a Bausch & Lomb catadioptric water immersion lens and the
Zeiss 32x/0,4 Glyc Ultrafluar, all of which behaved excellently.
At the time, a local Olympus engineer wanted to learn more about UV vs
visible chromatic aberrations of the lenses he sold, called us and asked
us to measure the aberrations of the objectives he had, among which a 10X
apochromat, which, however, never had been designed for UV wavelengths or
confocal microscopy. He just wanted to "get an idea about the aberrations"
and whether the lenses would be suitable for UV, even if they had not been
designed neither for confocal, nor for UV microscopy.
PLEASE NOTE! THESE WERE OLD STYLE LENSES (160mm tubelength), and at the
time considerably cheaper than lenses by other manufacturers!
If I recall correctly, we experienced at the time a more than 10 microns
axial shift between 365nm and 514nm, while there were, if I recall
correctly, a little bit more than 1 micron between 488nm and 514nm. The
measurements were done using a plane mirror as reflective specimen and the
mentioned aberrations were in the center of the field of view.
At the time, we did not have any deep blue laser line available, neither a
red one.
In order to not be misunderstood here:
These old Olympus lenses most probably cannot be compared to modern.
However, if you have an old lens, the values you indicate might be
absolutely correct.
Best wishes,
Johannes
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> Hello and happy holidays to everyone!
>
> Both of our 10/0.4 planapo objectives have a bad longitudinal chromatic
> aberration between blue and far red (2.5 um axial shift with correct
> coverslip). Is this normal for low-power objectives?
>
> Mike
>
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P. Johannes Helm
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