Mask Carrier for Scopes Without

[rnabholz]

My American Optical 20 scope is outfitted with a Phase Contrast Condenser. That condenser does not have a slot for masks or filters.

I enjoy experimenting with darkfield, oblique and van Egmond masks so I considered this something that I would need to address.

In order for these masks to work properly they generally need to be positioned as close to the condenser iris as possible, which is the normal placement for a mask slot or filter carrier. Looking over the AO 20, it occured to me that I might be able to fashion some sort of platform that would rest on the base and lift the masks to the proper height.

I have made other microscope accessories from closed cell foam and I turned to it again for this job. I did some measuring and found that the height from the base to the bottom of the condenser is around 7/8". My foam is 1/2" so two layers would be pretty close.

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The lamp aperture in the base is 1.25". I cut two 3" circles from the foam, and cut out a 1.25" circle from the center of both. I then made a cut taking about 1/8" of the thickness off of one of the "donuts". Stacked, they are now the correct height to fit under the condenser.

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The extra width of the donut creates a rest for the handle of my home made masks and allow me to manipulate and offset them as I might find necessary.

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To use, I place the mask on the donut, then place both on the base and slide them into place under the condenser. Watching at the eyepieces makes centering things easy enough. I can then manipulate the entire stack to fine tune centering, or grab the handle of the mask only and move only that to create a desired effect.

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The foam will not harm the finish of the scope, and can stay in place if desired as it does not obstruct the light source. The mask can be extracted and replaced with another very easily. The darkfield, oblique and van Egmond effects are just as good as I have been able to create with my other scopes.

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If your scope is slightly different in its configuration, you can easily cut foam pieces to fit nearly any situation you may have.

Hope some of you find this useful

Thanks for reading.

Rod

[gekko]

A simple and very elegant solution. I also admire your workmanship, especially the mask sets.

[billbillt]

This is a wonderful solution, Rod!... A great project and a great idea!..

BillT

[rnabholz]

Thanks for the interest gents.

So far, so good, it is working just fine, very cheap to put together too.

[Johann]

Very clever and simple - thanks for sharing

[rnabholz]

Very clever and simple - thanks for sharing

Thanks Johann.

[McConkey]

Hey Rod,
I'm using the AO20 too and this weekend i decided to try out your Van Egmond mask that you had available for download here. viewtopic.php?f=28&t=2686&hilit=van+egmond

It's been on my list on things to try for a long time but never had the chance to get around to doing it. The PDF you provided with all the masks is exceptionally helpful! I followed your advice and took them to Staples to be printed on over head projector transparency paper. Worked like a charm!

You mentioned that in order for these masks to work best they need to be as close to iris slot as possible, i came to the same conclusion and had a different idea.

I made the mask slightly smaller (same measurements as phase annulus inside the phase condenser), removed the phase annulus and re-placed it with the mask inside the phase condenser. See pictures below!

I hope you do not mind this modification on your work. I havn't had the chance to take any comparison images yet but so far the results are very nice.

Original mask is above modified smaller mask.

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[rnabholz]

Hey McC,

By all means, take any idea of mine and fold, staple mutilate, improve, rethink, debunk, whatever is productive or instructive.

It had not occurred to me to use the phase turret, I will be interested to hear about your experience and results.

I will say that based on my experience with these masks, being able to manipulate the position is helpful and creates some opportunities for interesting imaging. Offsetting them produces all kinds of different effects, and tweaks to centering can be helpful.

I will be watching for word on your innovation! Thanks for posting here.

Rod

[McConkey]

Thanks Rod!
The smaller version i made works perfectly for a 10x objective. I'm making the mask smaller and smaller and try and match it with the 20x, 40x and 100x objective to see if i can get the same results i'm getting with the 10x. It really is incredible how much of a difference this little filter makes. I'll shoot you a PM when i have everything matched up to the objectives.

[DonSchaeffer]

Neat thinking. I can put a filter right on top of the light source itself!

[rnabholz]

Yes.

You may find the closer you can get the filter or mask to the bottom of the condenser, tbe better the effect will be.

The great thing about DIY is the experimentation. Good luck.

Rod

[DonSchaeffer]

Starting with rudiments.
I made a cardboard tube and put it around the light source.

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Then I put a piece of carboard on top of the cardboard on top of the tube.

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As I move the cardboard across the tube I get some dark field effects.

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(well you get the idea)

[DonSchaeffer]

Thanks rnabholz. This simple playing around can greatly amplify what I can do with the microscope.

[rnabholz]

Glad it is working for you.

Here is another DIY that I have come to use a bunch.

viewtopic.php?p=42429#p42429