Re: How to setup Zeiss DIC?

On 28 Jul, 12:52, selwyn.stle...@xxxxxxxxx wrote:
On Jul 7, 1:34 pm, "Theo Griep" <gr...@xxxxxxxxx> wrote:





I want to use DIC for observing biological materials in transmitted light,
like single cell organisms.
Searching in books and on the web there seem to be 1001 ways to get (sort
of) DIC.
But what do I need and how can I make it work?

What I've got:
A Carl Zeiss standard microscope, several objectives (normal and phase
contrast)
A Carl Zeiss Inko condenser, with positions 2 and 3 for phasecontrast, and
I, II, III, IIII, n.a. 0,32 with front lens achr.apl. 1,4
Some sort of intermediate thing from Olympus that contains a slider and in
which an objective can be mounted, with
the text 'MPlan 100  11x'  on it (for reflected light?).
Polarizers

My questions:
- what other parts do I need to make the DIC condenser work
- which parts should be placed where on the microscope
- how to allign things properly

Thanks for any information or useful links

Theo

Hi,

If your Inko condenser has part number 4885059 (inscribed below "Karl
Zeiss" on the top surface) then you need the Zeiss type III slider
which fits into a Zeiss intermediate tube between the binocular/
trinocular head and the rest of the 'scope on Zeiss Standards. In this
system there is the one slider for all objectives so you wouldn't need
slider attachments for each objective. Unfortunately, with the Zeiss
Standard you can have either this tube or an optavar in place but not
both at once. Of course unless you need DIC or some other facility
necessitating an intermediate tube such is not necessary.

The DIC positions on your condenser refer thus:

I    - 16x objective
II   - 40x objective
III  - 100x objective
IIII -  6.3x objective (an afterthought by Zeiss?)

Objectives of differing magnifications will work to some degree but
not may not give optimal contrast or uniformity of the background
field.

To use position IIII most effectively (i.e. properly fill the field of
view with light in Kohler position) you need a 0.63 NA condenser top
to screw over the 0.32 front lens. This should be pol apl (red
markings) like your other tops.

For this system Zeiss recommended planachromats though you can get
good results with a more highly corrected objective lens; seems to be
a matter of the position of the objective back focal plane. I find a
Zeiss planapo 40x dry 0.95 NA objective gives excellent results. The
system also works quite well with 30x, 40x and 70x Lomo water
immersion achromatic objectives.

Zeiss recommend oiling the condenser (presumably for positions I, II
and III because it doesn't make much sense for position IIII) to the
slide. I rarely do this as it makes little apparent difference with
objectives up to 40x.

This, the second of the three Zeiss 160mm stand solutions, gives
excellent DIC.

Partially withdrawing the slider (and optionally removing the substage
polarizer to give more light) is necessary for phase contrast and
brightfield work. Brightfield necessitates there being a DIC condenser
prism in place as the condenser has no such position. Occasionally you
will get better results by swapping in a dedicated brightfield
condenser or you could consider getting a phase condenser with phase
positions 1, 2 and 3 plus brightfield and a darkfield stop for low to
moderate power darkfield. Unfortunately, many condensers have an empty
phase 1 position presumably because low power phase contrast work was
not popular.

Selwyn- Hide quoted text -

- Show quoted text -

Ref: leaving DIC prisms in place for BF and PC work. All the zeiss
manuals say it's OK to leave one prism in place (behind the objective)
when not doing DIC but I found this does degrade the image in some
cases - particularly at high NA.

It makes sense really, Wollaston prisms split a beam (image) onto two
separate paths displaced by a small amount (less than the smallest
resolvable distance for the objective in use). Although you can't SEE
two images, it does soften the edges of the very finest details a
little. If you leave one of the polarizers in place, the effect is
directional too. You'll always get a crisper image (in BF and PC) if
wollaston prisms are removed from the light path. But it's a very
subtle effect, so for general work you'll probably not notice the
difference with the prisms in place; the Zeiss advice is valid.

Note: my Zeiss DIC system has dedicated prisms behind each objective,
I'm guessing that the same principle applies to the version being
discussed here.

Cheers
Beats
.

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