OK what about Zeiss standard DIC?

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waterbear
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OK what about Zeiss standard DIC?

Post by waterbear »

In my search for DIC info, I naturally came across old built-like-a-tank Zeiss scopes. I saw a few Zeiss condensers for sale with one arrow symbol or two arrows.

Anyone got a view on which system is best and ideas on objective compatibility/availability?

Maybe this is an option for transmitted light DIC on a budget (well maybe not a "budget" by the time I have all the parts anyway). :wink:
Leitz Orthoplan

JohnyM
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Post by JohnyM »

Check out PZO DIC "UPI". One of most advanced and also cheapest DIC systems i know.

Old Zeiss (West) is notorious for delamination. I've bought few pieces of those systems in pristine condition that... still went bad after short (relative) time.
On the other hand Zeiss Jena is of excellent quality, but coarsly build in comparision to West.

Late infinite west optics, or infinite optics after merging is free of that problem.

Ichthyophthirius
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Re: OK what about Zeiss standard DIC?

Post by Ichthyophthirius »

waterbear wrote:I saw a few Zeiss condensers for sale with one arrow symbol or two arrows.
Surely not two arrows.

There are two main DIC systems for the 160 mm Zeiss West microscopes (INKO = Interferenzkontrast): http://www.photomacrography.net/forum/v ... 113#182113

1) INKO "old" with a condenser (single arrow) and one large objective-side prism (I, II or III) for all objectives. The objective-side prism is mounted in an intermediate tube (there are different versions, not all are compatible).

2) INKO "new" with a condenser (two options: normal NA 1.4 (46 52 85) and long distance NA 0.63 (46 52 73) mainly for inverted microscopes) and small objective-side prisms, one for each objective. An intermediate tube is also needed to mount the analyser slider. The "two arrows" "S" and "T" indicate the different condenser prism configurations for small and large Zeiss microscopes.

http://www.photomacrography.net/forum/v ... p?p=217306

INKO "old" is a bit cheaper as you need only one objective-side prism and mainly accommodates objectives 16:1, 40:1 and 100:1 (although a few off-label combinations also work).

INKO "new" is more flexible but the more exotic prism sliders can be very expensive. http://www.microscopeitaly.it/2009/11/3 ... -versione/

All suffer from delamination. This makes it difficult to find a setup in good conditions but on the other hand, prisms with small areas of delamination still work (especially if it is just the condenser) and can be a real bargain.

You need to be patient and wait for months and years until you got all the parts together for a good price!

waterbear
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Post by waterbear »

thanks very much this forum is a wealth of information - I'm doing more research. It seems that there are some of the latter and possibly more desirable DIC sets available but if delamination is a problem then it's probably down to temperature and moisture changes in a short space of time. That certainly rules out shipping from overseas at this time of year anyway. I opened an objective from the USA the other day and it had condensation forming on it instantly it was almost frozen :).
Leitz Orthoplan

Ichthyophthirius
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Post by Ichthyophthirius »

waterbear wrote:That certainly rules out shipping from overseas at this time of year anyway. I opened an objective from the USA the other day and it had condensation forming on it instantly it was almost frozen :).
You're right, winter shipping is always problematic for these items! I wouldn't risk it this time of year.

Even in spring or autumn, it's wise to leave the package for 24h at room temperature before opening it. Delayed gratification :)

viktor j nilsson
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Post by viktor j nilsson »

I am not really planning to shell out the dough needed to put together a DIC system, but I have been reading a lot of DIY DIC threads with great interest lately. (is that the first symptoms of DIC stepwise acquisition disorder?).

Anyway, now that JohnyM and others are listening, i have a question:

What are the parameters that determine whether two Nomarski prisms match 1) each other; and 2) a specific objective?

I've noted that there is a russian distributor that sells Nomarski prisms: http://opticsprovider.com/optics/nomarski-prism
I have no idea what they cost, but it made me curious to know if it's possible to put together a system from just the raw prisms. It seems like matching prisms from different makers and versions is hit and miss. But what if you start out with a new, matching set?

So: What parameters do you need to consider to put together a DIC system that works for a couple of different objectives, say a 20x PA and a 40x or 60x PA?

waterbear
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Post by waterbear »

Good idea. Wouldn't it be great if we could all re-invigorate DIC for old scopes which were on the junk pile?

I'm guessing parameters would be relating to numerical aperture and focal ratio (steepness of the light cone emanating from the objective).

I imagine that is thickness and angle, and extinction amount seems to be constant in their specs.

They are saying 30 arc sec deviation so it appears to be quite a tolerant system. 1/4 wave in red light isn't too accurate either to be honest. I would expect that green light where the eye is most sensitive. 4 surfaces = one whole wave. That is not accurate by any means but it may be all that's required at these long focal ratios. Not sure maybe someone can comment?

They also say they offer housings, so perhaps they are used to making them to spec and may even already know the parameters from buying old delaminated zeiss prisms, and measuring the thickness and angles, so one just needs to describe the system to them? Or send them some junked components.

They offer Senarmon, which it appears is better than Nomarski or at least more convenient to use (I have been reading about it on the Nikon website). If they could offer that for Zeiss 160 and Leitz 170 TL systems I for one would jump at it. Even infinity, anything to avoid buying stuff which may or may not work on eBay :)
Leitz Orthoplan

Pau
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Post by Pau »

Mixing and matching DIC components is risky and full of uncertainty although in some cases it works. *
waterbear wrote:...
I'm guessing parameters would be relating to numerical aperture and focal ratio (steepness of the light cone emanating from the objective).

I imagine that is thickness and angle, and extinction amount seems to be constant in their specs.
...
AFAIK the amount of shear and the focal distance where the interference band is placed (Nomarski prisms have it located outside the prism) to match the objective rear focal plane are main parameters. Unfortunately makers do not disclose them and I lack the knowledge and tools to measure it.
Also the objective rear focal plane is not standardized and many objectives can't deliver DIC. With my system I can't get DIC with any phase objectives I've tested, for example, but I get decent DIC with some non phase Leitz NPL fluotar and Pl Fluotar (160), Zeiss Planapo and and Nikon CF Plan Apo, even with a highly mismatched Nikon CFI Plan Apo 20/0.75.

I agree with Johny about the PZO system: because it is highly regulable it can work well with many objectives not designed to work with it like Nikon CF and Leitz NPL fluotars

* see my hybrid setup at http://www.photomacrography.net/forum/v ... hp?t=15606
Pau

abednego1995
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Post by abednego1995 »

Well, the main parameters for making a Nomarski prism would be the apex angle (alpha) and the section angle (beta). Shear amount is dictated by the apex angle, and where the interference plane comes, by the crystal(mostly quartz) axis section angle.

Image

The most important equation your optics have to fulfill in DIC would probably be the function which describes "pupillar compensation"
Image

fc: condenser focal length
alphaQ: condenser prism wedge angle
fob: objective focal length
alpha: objective prism wedge angle


I'll skip other mathematical magic involved, but in systems where there is only one translating prism above the objective the only parameter easily changed would be alphaQ, with the condenser prism. This explains when only one prism is at the objective side, multiple prisms are required for the condenser (of course you still have to consider the aperture, but that is another story.) And when the shear amount is dictated by the NA of the objective (it must be under the resolution limit for obvious reasons), you get a quite tight design margin for the apex angle of the objective prism, typically 0.5-1 degrees from low to high NA.

What I'm guessing is, most Nomarski DIC prisms that are made for same magnifications and NA might have very similar apex angles with different section angles.

So, if you already have a DIC condenser and a few mismatching nomarski prisms sitting around, being careful to match the objective prism to the indicated magnification, and getting the prism interference plane to coincide with the BFP of your objective might suffice. i.e, if you can vary the position of the objective prism vertically, even in ill performing setups, there is a possibility of resurrecting your Frankenskop (again?).

Cheers,
John

viktor j nilsson
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Post by viktor j nilsson »

Thank you! That mostly match my intuition about the parameters involved. It seems like you could get a lot of different Nomarski prisms to play well together if you were able to move them vertically.

Pau
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Post by Pau »

abednego1995 wrote:Well, the main parameters for making a Nomarski prism would be the apex angle (alpha) and the section angle (beta). Shear amount is dictated by the apex angle, and where the interference plane comes, by the crystal(mostly quartz) axis section angle.

....
fc: condenser focal length
alphaQ: condenser prism wedge angle
fob: objective focal length
alpha: objective prism wedge angle
...

What I'm guessing is, most Nomarski DIC prisms that are made for same magnifications and NA might have very similar apex angles with different section angles.
With beta angle and section angle, do you refer to the angle the optical planes of both sections of the same prism? Is it what determines the distance of the interference plane to the prism?
So, if you already have a DIC condenser and a few mismatching nomarski prisms sitting around, being careful to match the objective prism to the indicated magnification, and getting the prism interference plane to coincide with the BFP of your objective might suffice. i.e, if you can vary the position of the objective prism vertically, even in ill performing setups, there is a possibility of resurrecting your Frankenskop (again?).
I've tried it with different prisms for reflected DIC as objective prisms and none of them worked. I've also tried my Oly U-DICT at different positions trying to improve evenness without positive results (but getting negative ones :? ).
What I do as a routine with big effect is to move the condenser up and down, in fact with most of my objectives DIC is realized a bit outside the ideal Köhler position.
Pau

abednego1995
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Post by abednego1995 »

Yup, the beta angle and section angle are the same and they determine the distance of the interference plane to the prism.
I've tried it with different prisms for reflected DIC as objective prisms and none of them worked. I've also tried my Oly U-DICT at different positions trying to improve evenness without positive results (but getting negative ones Confused ).
What I do as a routine with big effect is to move the condenser up and down, in fact with most of my objectives DIC is realized a bit outside the ideal Köhler position.
I'm also trying dinking around with those reflected DIC prisms since they are cheaper compared with those for transmitted DIC. I think what you're getting by moving the condenser up and down, is shifting the image plane of the condenser aperture and by doing so, matching the plane with the interference plane of the mismatched objective prism. It will mess up Koehler, but you're probably getting DIC in that way. I'm currently thinking of making a bare mount for the objective, and placing a positioning mount for the objective prism. It'll look more like a optical bench setup, but who cares? It could be cheap:-)

viktor j nilsson
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Post by viktor j nilsson »

Here's a few more question:

1) how is it possible for the first-generation Zeiss inko system to use a single objective prisms for all objectives? The more I think about it the weirder it seems. How would you design such a jack-of-all-trades prism?

2) is it really critical to place the objective prism exactly at the rear focal plane of the objective? It doesn't seem that way to me: some systems place the prisms immediately between the objective and the nose piece, and others (from the same maker) place them well above the objectives inside the nosepiece or inside an intermediate tube. Surely the location of the rear focal plane can't be that different among the objectives for those systems?

viktor j nilsson
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Location: Lund, Sweden

Post by viktor j nilsson »

abednego1995 wrote: I'm also trying dinking around with those reflected DIC prisms since they are cheaper compared with those for transmitted DIC. [...]
I'm currently thinking of making a bare mount for the objective, and placing a positioning mount for the objective prism. It'll look more like a optical bench setup, but who cares? It could be cheap:-)
Love this idea! I actually put in an offer for some reflected DIC prisms just to have something to play with, if I can get DIC to work with one or two objectives that'd be awesome, but at least I'll learn something (hopefully).

Ichthyophthirius
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Post by Ichthyophthirius »

viktor j nilsson wrote: 1) how is it possible for the first-generation Zeiss inko system to use a single objective prisms for all objectives? The more I think about it the weirder it seems. How would you design such a jack-of-all-trades prism?

2) is it really critical to place the objective prism exactly at the rear focal plane of the objective? It doesn't seem that way to me: some systems place the prisms immediately between the objective and the nose piece, and others (from the same maker) place them well above the objectives inside the nosepiece or inside an intermediate tube. Surely the location of the rear focal plane can't be that different among the objectives for those systems?
1) The single prism is designed to match the exit pupils of all 3 (4) objectives it was intended for, Plan 16, Plan 40 and Plan 100 (+ Plan 6,3). The objectives were re-designed for this; some older Plan 40s are incompatible.

Read more about the design here: https://www.microscopyu.com/pdfs/Allen_ ... 3-1969.pdf

There are then 3 (4) compensating prisms in the condenser to correct for all 3 (4) different magnifications.

Also, it's not a dated concept. Olympus and Leica are using single objective-side prisms. They have multiple condenser prisms to compensate. Zeiss and Nikon have multiple objective-side prisms and just a few (mostly 2) condenser prisms.

2) Some early interference contrast systems placed prisms directly in the back focal plane. The innovation of the Nomarski prism (over the Wollaston) was that the interference fringes are located outside the prism, so the prism could be placed outside the objective as well. Leitz was the only company that had prisms inside the objectives until the 1980s.

See here: http://olympus.magnet.fsu.edu/primer/ja ... index.html

Regards, Ichty

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