Home-Made Mikropolychromar Version 3.0

Images made through a microscope. All subject types.

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Donw
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Joined: Tue Jul 26, 2011 2:05 am
Location: Seattle

Home-Made Mikropolychromar Version 3.0

Post by Donw »

These are some results from a device I've been working on for some time. Versions 1 and 2 were mediocre at best. Version 4 is presently on the drawing board. Both stills and video were done with a 20X/.50 Plan Achro. Although I have an Aplanat 1.4 condenser, these were shot with an Abbe 1.25. Orange and Cyan filters for the marginal, and Dark Blue for the axial.

Version 4.0 should help reduce glare, and bring out finer details better.

Thoughts, feedback, observations and criticizims are welcome.

A Video, for your consideration:

http://youtu.be/9cX7rliW_JM

Image

Image

Pau
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Re: Home-Made Mikropolychromar Version 3.0

Post by Pau »

Donw wrote: Home-Made Mikropolychromar
Is it some kind of Reinberg filter?
Pau

g4lab
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Joined: Fri May 23, 2008 11:07 am

Post by g4lab »

Zeiss brand name for Rheinberg outfit made ages ago. Probably pre WWII.
Rare collectible and expensive when hey appear. Unitron built a copy too.

dolmadis
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Joined: Wed Dec 07, 2011 1:51 pm
Location: UK

Post by dolmadis »

Hi Don

You say "Home-Made". Would you be prepared to show us how? I am intrigued and very interested to see given the complexity of the Zeiss design.

Thanks


John

Donw
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Joined: Tue Jul 26, 2011 2:05 am
Location: Seattle

Basic Workings

Post by Donw »

All of the diagrams that I have been able to find of Zeiss' design are of poor quality, and a bit confusing. The device appears to be more complex than it really is.

The secret of their genius is a 'nested' diaphram system. There is an outer (or marginal) iris, which controls glare. There is also an inner (or axial) iris, which controls depth of field.

The problem with typical filters is that there isn't an effective way to control glare or DOF, which means that the IQ suffers, and the filters tend to give inconsistant results.

Glare here is basically the same problem with darkfield. Too much destroys the IQ. If you've ever made a DF condenser out of a typical abbe condenser, then you may have used the iris to control glare. Zeiss' design does the same thing.

Image

The other problem is DOF. Most Rheinburg filters don't offer any type of DOF control, which makes detail muddy, or washed out. The inner iris controls DOF exactly the way your iris does on any BF condenser. If the iris is stopped down too much, the IQ is muddy. Open too much, and the IQ is washed out.

I had originally (Version 2.0) planned to create stop rings I could change to adjust both glare and DOF. Unfortunaltly, as most of us have learned, small changes in the DOF iris make big changes in the final IQ. Realizing this, then I would need dozens of stops... perhaps enven a hundred or so. I deciede the best thing to do would be to do what Zeiss did. Use diaphrams.

The marginal diaphram is pretty easy to build. It is, basically, a modified BF condenser iris from an old abbe condenser. The axial diaphram wasn't too dificult for Version 3.0. I found a couple in my junk box that came with a microscope lot I bought a couple of years ago. Transplanting that into my own system was a challenge, but not impossible. The only problem is that it is too wide. Version 4.0 will feature a custom built iris, as it is unlikely that I will be able to find one that is the size I need.

This is a simple diagram of what I will build:
Image

The filters are modular, and can be stacked for different effects. They are placed in a tray (not shown), and the tray is slid into the filter holder.

The whole thing (except for the condenser and the centerable holder) is constructed of .5mm plastic sheets, each cut to a pattern, and then glued together. It doesn't look like much, but it is strong. It takes a lot of sissor and razor blade action, though...

dolmadis
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Joined: Wed Dec 07, 2011 1:51 pm
Location: UK

Post by dolmadis »

Hi Don

Thank you very much for that excellent explanation.

To say the least I now have something to study and think about in the dark hours of the winter !!

I have, personally, not come across an axial iris and I am having some trouble visualising this component. (I just might be thick !!)

If you or any other reader can provide a photo or a link to a photo of an axial iris alone and in situ then I shall be most grateful to extend my learning.

Regards, John

dolmadis
Posts: 900
Joined: Wed Dec 07, 2011 1:51 pm
Location: UK

Post by dolmadis »

Don (and anyone who would like to help/comment !!)

Do you think that the 1955 approach by Galbraith could be used in conjunction with a marginal iris/diaphragm (normal condenser) to get somewhere towards this in another way (but it might be the way you have built your version of the Mikropolychromar).

Looking for exchanges of ideas.

http://jcs.biologists.org/content/s3-96/36/515


John

Donw
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Joined: Tue Jul 26, 2011 2:05 am
Location: Seattle

Post by Donw »

I have, personally, not come across an axial iris and ...
It is really just two irises stacked on top of each other. The lower, and larger, is a slightly modified abbe iris from an old abbe condenser. The Axial iris is much smaller (V. 3.0 is about 13mm wide, 4.0 will be about 11mm wide.) than the larger iris, but the two do not touch each other.

The smaller iris is built up on clear plastic sheets so that light can get by it.
Do you think that the 1955 approach by Galbraith could be used in conjunction ...
I have not heard of this device before today, and I followed your link, but that didn't tell me much either. Version 2.0 used 'tombstone' filters, which 'work', in that you do get a Rheinburg effect. What makes the Mikropolychromar different is that you can control glare, and DOF which yeilds much more consistant results.

Rheinburg is similar to DF, in that too much glare diminishes IQ. With DF, you can control that by building a 'thin' slide, and or reducing debris on the slide, and or reducing smears, fingerprints, etc on either the slide or cover slip. Those techniques work well with the MPC, and having an iris to help control glare goes along way in improving IQ.

The smaller axial iris controls DOF (and therefore contrast), just the way your iris in a brightfield condenser does. With the old tombstone filters, their was no easy way to adjust the size of the inner stop. Having a small diaphram really makes a big difference in IQ.

This condenser I've built works best when oiled (like a DF condenser), and can be used as a DF condenser. (Although I like my dedicated DF condenser better) It can also be used as a BF condenser (Although I prefer my dry dedicated BF condenser better).

My MPC condenser is centerable (an old DF condenser mount). Ziess' wasn't centerable, even though it used an Aplanat 1.4 condenser. Ziess' worked well as an oblique condenser, simply because the device could be swung aside on the light path. So far, I haven't been able to get good oblique results, although I haven't placed too much emphisis on that yet.

Ziess' plan called for a dedicated illuminator cliped to the bottom of the condenser unit. Their plan uses both UV filters and frosted glass to deal with UV and a harsh bulb filiment. My design uses my microscope's Kohler (SP I am sure...) illumination, so I didn't need to add these elements to my design...

V 4.0 is coming along well. It is much thinner than 3.0, so it fits under the stage better. Now, I have to make the axial iris blades (16 of them! 4mm long, and 1mm wide... thank god I have a stereo microscope to cut them out) It will take a couple of days to get everything up and running...

dolmadis
Posts: 900
Joined: Wed Dec 07, 2011 1:51 pm
Location: UK

Post by dolmadis »

Thanks Don. I follow and now visualise the device you are prototyping.

I am fascinated by this and would like to create one as well.

Do I assume that you do do not install your version under a standard condenser? It is a standalone?

Regards

John

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