American Optical 110 Darkfield Patch Sizes

Here you can discuss different microscopic techniques and illumination methods, such as Brightfield, Darkfield, Phase Contrast, DIC, Oblique illumination, etc.
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farnsy
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American Optical 110 Darkfield Patch Sizes

#1 Post by farnsy » Sun May 02, 2021 8:34 am

I have tried darkfield patch stops and Rheinberg filters from ebay for my AO 110, but they are neither the right size of filter nor the right size for the cone of illumination. The AO series 110 condenser (cat 1087 is what I'm using) has a larger filter tray (34.5mm) than the series 10 condensers (33mm, I think), and than many current-model microscopes (often 32mm). I have a 3D printer, so I decided to make up darkfield patch stops that fit perfectly in this tray (34.85mm) and then try increasing the central disk size by 1mm in order to figure out the smallest size for each objective I use. After a bunch of experimentation, I have found that the sizes are

4X plan .12 NA (without swingout lens): 5mm patch stop
10X plan .25 NA: 6mm or 7mm patch stop
20X plan .50 NA: 11mm or 12mm patch stop
40X plan .66 NA: 15mm or 16mm patch stop

Image

If you have access to a 3D printer and want to print these, you can grab the stl files at https://www.thingiverse.com/thing:4846300.

Now that I have figured out the actual size of the central area, I will go back and make Rheinberg patches, with a ring separating the inside color and outside color. I'll use photographic gels for the color, most likely. I suppose you could use these measurements to make good DIY or printed patches on transparency film if you want.

When I get Rheinberg working well, I'll make up some oblique illumination patch stops. I'll post both here in this thread.

dtsh
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Re: American Optical 110 Darkfield Patch Sizes

#2 Post by dtsh » Sun May 02, 2021 5:01 pm

I created a simple adapter for the AO filter slots to allow typical 32mm filters to be used.

https://www.thingiverse.com/thing:4836163

It's also usable as an oblique illumination stop, but I need to make it a tad longer to do that well.

farnsy
Posts: 209
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Location: Fort Worth, Texas

Re: American Optical 110 Darkfield Patch Sizes

#3 Post by farnsy » Sun May 02, 2021 5:36 pm

Very nice indeed! Is that for the 110 series (34.5mm)?

dtsh
Posts: 977
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Location: Wisconsin

Re: American Optical 110 Darkfield Patch Sizes

#4 Post by dtsh » Sun May 02, 2021 8:57 pm

farnsy wrote:
Sun May 02, 2021 5:36 pm
Very nice indeed! Is that for the 110 series (34.5mm)?
My apologies, I thought the 10, 110, and 410 series all had the same size slot.

I have since lengthened it and made a version for the 110 and 410. Thanks for letting me know. You'll want the "ao_filter_holder_34.5.obj" file for the 110.

https://www.thingiverse.com/thing:4836163

farnsy
Posts: 209
Joined: Mon Jun 17, 2019 9:03 pm
Location: Fort Worth, Texas

Re: American Optical 110 Darkfield Patch Sizes

#5 Post by farnsy » Fri May 07, 2021 6:23 am

OK, so I'm kind of on an openSCAD kick and I have rethought these filters. I also have a gimp python script that makes Rheinberg and other colored filters for me whatever size and aperture I want and I realized that is awfully convenient to combine with these patches but quite difficult to work with on its own (not enough structure in the transparency paper). So I redesigned my inserts. I'd be interested in some comments. These are all parameterized, so I will ultimately post the code that works with any size filter slot, any NA aperture, any filter insert size, and any desired thickness. Take a look

Image

I find these infinitely more convenient than what I showed before. Each one holds a 32 mm filter in addition to what it provides, and there is a little recess that holds flimsy filters in place. The lower left grouping is darkfield, obviously. The lower right can hold any type of filter (the inner circle is just outside the direct light cone), but I intend it for if I get really crafty with photographic gels--because they are better than printed Rheinberg filters. The upper right is for generic filters of any kind. The one in the middle is a slight modification with a smaller handle for polarizing filters (the smaller handle allows you to rotate it a little more).

In the upper right I have a couple of oblique illumination filters--I haven't printed the ones for other objectives yet. There are many other patterns one can use for oblique illumination, but I'm not really sure how much difference there is between one and another. Is there a pattern that works better that you suggest?

Ultimately I will post the python script that makes Rheinberg any color and size you want, along with all these designs.

So far these have been working much better and more conveniently, but I'm interested in suggestions. Is there a pattern you would like me to make for you, anyone?

PondScum
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Re: American Optical 110 Darkfield Patch Sizes

#6 Post by PondScum » Tue May 18, 2021 11:51 pm

farnsy wrote:
Fri May 07, 2021 6:23 am
So far these have been working much better and more conveniently, but I'm interested in suggestions.
Well, I think they look great, and it is awesome that you are willing to share the fruits of your labor! Being very new to microscopy I don't really have any functional suggestions, but since you are asking... one thing that might be nice would be to include raised lettering on the tabs (e.g. 20x, 40x, etc) so that you don't also have to make labels. That way they would be nice and neat looking, and you would never have to worry about the labels coming off. I don't know how hard it would be to do in your software, but if it is relatively easy it might be nice.

farnsy
Posts: 209
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Location: Fort Worth, Texas

Re: American Optical 110 Darkfield Patch Sizes

#7 Post by farnsy » Wed May 19, 2021 6:06 am

PondScum wrote:
Tue May 18, 2021 11:51 pm
Well, I think they look great, and it is awesome that you are willing to share the fruits of your labor! Being very new to microscopy I don't really have any functional suggestions, but since you are asking... one thing that might be nice would be to include raised lettering on the tabs (e.g. 20x, 40x, etc) so that you don't also have to make labels. That way they would be nice and neat looking, and you would never have to worry about the labels coming off. I don't know how hard it would be to do in your software, but if it is relatively easy it might be nice.
I thought about that. I can certainly do it, but on the black plastic, I don't think it would show up well. I could probably make the letters go all the way through, though. Then you would be able to see it.

I'll give it a shot. Thanks for the idea. I'll post a bunch of designs here soon...I want the whole complement. My code is flexible enough to accommodate any filter size or thickness, with or without handles.

edit: I'll just attach a quick render now of the filters I have, with words. All these sizes, spoke numbers and lengths, and angles are settable, but these give you a basic idea of what I have so far. Still interested in more designs people might want.

Image

dtsh
Posts: 977
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Location: Wisconsin

Re: American Optical 110 Darkfield Patch Sizes

#8 Post by dtsh » Wed May 19, 2021 12:37 pm

farnsy wrote:
Wed May 19, 2021 6:06 am
I thought about that. I can certainly do it, but on the black plastic, I don't think it would show up well. I could probably make the letters go all the way through, though. Then you would be able to see it.

I'll give it a shot. Thanks for the idea. I'll post a bunch of designs here soon...I want the whole complement. My code is flexible enough to accommodate any filter size or thickness, with or without handles.

edit: I'll just attach a quick render now of the filters I have, with words. All these sizes, spoke numbers and lengths, and angles are settable, but these give you a basic idea of what I have so far. Still interested in more designs people might want.
I have had good luck filling recessed lettering with a contrasting paint, then gently wiping off the surface to leave the paint in the recesses, but remove it from the rest. Might not be worth the effort for most people, but I've done that with some eyepieces, objectives, and a variety of non-microscopy objects and it works pretty well.

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