Diameter of black disc for darkfield?

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Saul
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Post by Saul »

Accidentally I was reading the same article yesterday - anybody knows more details about bispheric double reflecting condenser ? Why it is so special ?
Saul
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GaryB
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Post by GaryB »

Saul wrote:
Accidentally I was reading the same article yesterday - anybody knows more details about bispheric double reflecting condenser ? Why it is so special ?
It's just one of the many types developed over the years and shown in this pdf. I don't know why it would be special, though it seems to resemble the basic working principal of the leitz heine condenser but at a hgher .na and specifically for darkfield.
http://www.med.unc.edu/microscopy/files ... dark-field

Saul
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Post by Saul »

GaryB wrote: It's just one of the many types developed over the years and shown in this pdf. I don't know why it would be special, though it seems to resemble the basic working principal of the leitz heine condenser but at a hgher .na and specifically for darkfield.
http://www.med.unc.edu/microscopy/files ... dark-field
Thanks ! I read that also :) Is this reflection ball is movable ?
Saul
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GaryB
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Post by GaryB »

No, they're all fixed as far as I've been able to determine. A movable dome would certainly be a great step forward, though I think it would need to be a parabaloid shape rather than dome, same with the reflector for true versatility. I would love to see that made. Even just molded/machined acrylic with some chrome plating would be a good start as a prototype... *hint to any designer types out there* :wink:

Saul
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Post by Saul »

GaryB wrote:No, they're all fixed as far as I've been able to determine. A movable dome would certainly be a great step forward, though I think it would need to be a parabaloid shape rather than dome, same with the reflector for true versatility. I would love to see that made. Even just molded/machined acrylic with some chrome plating would be a good start as a prototype... *hint to any designer types out there* :wink:
Started already.... but need community help.
https://www.3dvieweronline.com/members/ ... S6UtuA9lyP

Dome will be movable. Another question - picture from the Olympus website says that it is from solid glass . What - all shell or base filled filled with solid glass ? If it is 2nd option - is this surface reflective ?
Saul
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dolmadis
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Post by dolmadis »

Hi Saul

I hope this post might be of some help.

There is a mention of a "Bispeheric Double Reflecting design" referencing a Reichert immersion high NA DF condenser on the "Microscopy as a hobby......" Yahoo Group.

https://groups.yahoo.com/neo/groups/Mic ... pics/71129

There is a link to a photo album.

http://groups.yahoo.com/group/Microscop ... 9/pic/list

Also I have found an Ebay item with photos to view assuming that this is the same Reichert design.


https://www.ebay.com/itm/302680002061?V ... 2680002061

HTH

BR


John

Saul
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Post by Saul »

dolmadis wrote:...I hope this post might be of some help...
Thanks John !
Cannot see photos - "You need to be a member to perform this action."
How to become a member ? Help says, that I have to have an invitation ?
Saul
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dolmadis
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Post by dolmadis »

I would invite you if I could see where/how !!

Perhaps another Member here knows?

BR

John

Smokedaddy
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Post by Smokedaddy »

... all you have to do is click on MICROSCOPE on the left then select JOIN.

Saul
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Post by Saul »

Smokedaddy wrote:... all you have to do is click on MICROSCOPE on the left then select JOIN.
Thanks James, it took forever for Yahoo to load that MICROSCOPE banner, now I can see photos :)
Saul
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ChrisR
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Post by ChrisR »

Also NB, the Yahoo Microscope group is not the same as the Yahoo Microscopes group. I was a member of one but not the other!
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Post by ChrisR »

Does anyone have a pattern for a set of "petals" to make one of the adjustable "rose" stops?
I could get one (or more) laser cut. Not from metal though, afaik.
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zzffnn
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Post by zzffnn »

ChrisR wrote:Does anyone have a pattern for a set of "petals" to make one of the adjustable "rose" stops?
I could get one (or more) laser cut. Not from metal though, afaik.
I don't, but I will happily join a group buy, if you or anyone makes such an adjustable rosette / reversed iris. I prefer more leaflets to make a relatively smooth circle, if possible.

I am interested in Saul's condenser lens too and can compare it to my Leitz Heine. I am moving though (and microscopy items are boxed up), so it will take a month or two, if my comparison report is needed.
Selling my Canon FD 200mm F/2.8 lens

phil m
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Post by phil m »

I will dig out my version of this, sometime today and offer up some measurements.
Many condenser diaphragms use brass pins at each end of the leaves, to actuate the motion of the leaves. Some have the pins set into the leaves but some have the pin set in the outer ring and the leaf has a hole in it that rotates about the pin. An old condenser , either with or without fixed pins, because they could be pressed out, would serve to provide leaves for a variable DF stop. The leaf ends could be stacked on a central shaft. Shaping would take a bit of fiddling but they can be cut to size easily.
One might even be able to adapt an old iris diaphragm housing to the task.

ChrisR
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Post by ChrisR »

I've dreamt up a way to make an expanding "circle", but I'm sure someone did it better a long time ago.. What range of diameters would be needed?
Depends on the condenser height?

I'm not sure of the resolution of the laser cutter. I know it won't cut metal, but probably would do something suitable. Any suggestions? "Delrin"?
Res of the most accurate 3D printer I have access to is 20µm.
Chris R

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