EPI dedicated hybrid

Here you can discuss different microscopic techniques and illumination methods, such as Brightfield, Darkfield, Phase Contrast, DIC, Oblique illumination, etc.
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georgetmacro
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EPI dedicated hybrid

#1 Post by georgetmacro » Sun Apr 21, 2019 5:54 am

Hi. I am in the process of setting up one of my microscopes as a dedicated EPI unit. I have got it to the point that I know it works but I have no RMS EPI objectives. Does anybody either have any they can sell to me or let me know where I can get them without breaking the bank. There are plenty on eBay in the USA but they are terribly expensive and the postage is a lot also. There are some EPI objectives available from people selling from Russia and Ukraine but they are all 190 tube length and 27 mm mount units. My email is georget029@yahoo.com.au if anybody has anything they can help me with.
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abednego1995
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Re: EPI dedicated hybrid

#2 Post by abednego1995 » Sun Apr 21, 2019 9:46 am

Hi George! Nice setup, but I'm curious on how you managed to get TL160mm on it.

Cheers,
John

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zzffnn
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Re: EPI dedicated hybrid

#3 Post by zzffnn » Sun Apr 21, 2019 2:22 pm

Welcome to the forum, George!

I have the same question about tube length.

The tube length in that photo of yours may even exceed 210mm.

I have not used any illumination-through-objective kind of true epi objectives. But you may be able to buy RMS adapters (such as 27mm-RMS) from eBay.

LOMO epi objectives are not expensive, but I heard that they are not parfocal with each other.

I only use overhead (oblique) reflected diffused light with no-cover objectives. They are usually not expensive in USA. Nikon made some short (~33mm parfocal) Nikon S no-cover objectives before and you CMA find them cheaply in USA. Don't know about Australia though.

MicroBob
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Re: EPI dedicated hybrid

#4 Post by MicroBob » Sun Apr 21, 2019 5:15 pm

Hi George,
you should first decide what kind of epi illumination you want: Brightfield, brightfield polarized, darkfield or DIC.
The choice depends on the objects you want to observe.
Useful and simple is brightfield polarized. Illumination is directly through the objective, you put linear polarizers after the lamp and in front of the eyepiece tube in crossed arrangement.
For objectives up to 10:1 you can use normal compound microscope objectives.
For higher magnifications you should use objectives that are not calculated for use of a cover slip, so no "0,17" engraved on them.

Epi objectives for darkfield usually have bigger threads than RMS.

On the german used market epi objectives are not more expensive than usual objectives. They are less common but there also is less demand.


I would first check whether your setup is usable tube lenght-wise. Does the image stay roughly in focus when you change the objective?
If you live in an area with a rich used market it might be easier to buy a complete epi microscope that to assemble a working component mix.

Bob

Hobbyst46
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Re: EPI dedicated hybrid

#5 Post by Hobbyst46 » Sun Apr 21, 2019 6:16 pm

MicroBob wrote:Epi objectives for darkfield usually have bigger threads than RMS.
Bob, this is so with Nikon Optiophot objectives, which are RMS and DIN; yet, according to some web literature, I understand that older Nikon S objectives, including EPI objectives, are short barrel and of RMS thread.
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

MicroBob
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Re: EPI dedicated hybrid

#6 Post by MicroBob » Mon Apr 22, 2019 4:53 am

The choice of objective depends also on the reflector in use: For brightfield a semi-reflecting surface is needed, for darkfield a ring mirror outside the central area.
For dark field mixing components will be especially difficult, because the microscope makers chose different designs to get the light to the ring mirror. Zeiss Jena used normal sized infinity objectives and a very big ring collar diameter, I think Vickers had the lightpath inside the RMS thread.

Bob

georgetmacro
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Re: EPI dedicated hybrid

#7 Post by georgetmacro » Mon Apr 22, 2019 1:20 pm

Thanks, everybody for the advice/suggestions. I think, Bob, your suggestion of sourcing an epi microscope is probably the way to go. I have asked one of the Russian eBay suppliers to put something together for me to think about. He is suggesting an epi M27 microscope (MMU-1 or MMU-3), Lomo I guess, together with an OI-31 vertical illumination unit and set of epi objectives. I am really only interested in brightfield at the moment for the archaeology studies I can do dark-field in other ways using standard objectives. I am not quite sure how to go about setting up an epi system up using a standard microscope and it seems there would be a compromise unless I am able to get the correct gear together.

apochronaut
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Re: EPI dedicated hybrid

#8 Post by apochronaut » Mon Apr 22, 2019 1:44 pm

Eyeballing your set up, it looks like it would be 250mm , or more likely more. If it turns out that your tube length is too much for the economical conventional fixed tube objectives available to you, you might try the short tube parfocal( 34mm) AO epi objectives, since they are infinity corrected and the longer tube would only result in some increased magnification if it wasn't too much( over 300mm). The nominal length for those is 200mm. You would need a telan lens from a derelict head to put into your optical path, at the correct distance from the eyepiece. Threads are RMS for those objectives. You would probably be best to use an AO eyepiece as well. Cat.# 180 can be found quite cheaply and they are 20mm f.o.v.
The objectives themselves are fairly common and go 5X,10X,20X, 40X to 60X .85 and are all plan achromats. They can be expensive if purchased on ebay but every now and then some come along for $30 or $40 + shipping. Sellers don't seem to know what to charge for them, and because they are fairly heavy and look a bit fancy, some sellers go high. Shipping would be from U.S so the cost might go over your budget, even with a cheaper price on the objectives themselves. They use a ring type illuminator.

There are also the fixed tube Bausch & Lomb and they have a ring type illumination path too. They are 215mm tube length and R.M.S. and are a much lighter objective than the AO because the barrels are aluminum. I don't think they are plan.

Here are some links from ebay sources as to what they look like. They are both too high a price but my experience with silosurplus is that they will often take 1/3 of what the asking price is, especially if you buy more than one item and they combine shipping. 5 items will ship for the same price as one.
https://www.ebay.com/itm/MICROSCOPE-PAR ... Sw8vZXORcV
https://www.ebay.com/itm/MICROSCOPE-PAR ... Sw4SlV8DIa

There is also this set here. These are for use on a Balplan frame. There is a telescope lens just above the nosepiece necessary to use these objectives. The telescope lens could be installed in another frame or sometimes a derelict Balplan frame without objectives shows up. There is no tube length; it is irrelevant, since the tube length is modified to infinity after the telescope lens.
The price is right for a complete set, if one wanted to do some fiddling around. Multiples of each of 5x, 10x, 20x and 40X epi planachros.
https://www.ebay.com/itm/Lot-Of-BAUSCH- ... SwpPNct9-A
The telescope lens is available new from at least one supplier I know of and probably used from one other. Balplans were quite popular in their day, so there are quite a few frames and parts around. Optically excellent.

georgetmacro
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Re: EPI dedicated hybrid

#9 Post by georgetmacro » Tue Apr 23, 2019 5:44 am

Hi again guys. I am looking at modifying my epi arrangement based on this discussion. What I have come up with so far is to place the illuminator directly on top of a Nikon 'S' series polarizer (see image) that is sitting directly above the nosepiece. This will reduce the tube length to ~188 mm. There is not much room under this polarizer to fit a telescope lens unless it is around 17.17 mm dia. Because the polarizer has it's own optics would this not be already creating a parallel beam. By the way, is a telescope lens just a single convex lens with the curved surface on the subject side? I cannot test this arrangement yet as I have a couple of the joining components awaiting super-Araldite curing.
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apochronaut
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Re: EPI dedicated hybrid

#10 Post by apochronaut » Tue Apr 23, 2019 3:03 pm

The telescope lens required for the B & L optics is specific to those optics. The objectives are semi-objectives, with the telescope lens contributing 5X magnification as well multiple corrective properties into an infinity tube length , to each objective in turn. It is a convex/concave meniscus doublet of 10mm diameter. The focal length is .177 of the object to image distance of the entire objective system. Unfortunately, I don't know what that is, although at some point I could measure it. There is no way, any but the original factory lens would work in that application because the corrective properties it is engineered to perform are known only to the engineers. It is essentially, the rear lens element of each of the objectives and thus makes the objective system around a 60mm parfocal system.

The lens is fitted into an approximately 30mm housing which is then fitted into the upper section of the nosepiece. Acquiring a used Balplan nosepiece, would most likely also include that lens unless it had been removed, and would be the easiest way of finding that lens.

Here is a listing that shows the location of the lens in a 5 hole nosepiece. https://www.ebay.com/itm/Bausch-Lomb-Ba ... Sw7NNT9Qga That particular seller is a bit out to lunch as to the actual aftermarket value of what they are selling, so just ignore the price. There have been numerous incidences of entire nosepieces with objectives selling on ebay for 50.00, even less. The same lens is in the flat field Dynoptic or Dynazoom microscope too, so one of those nosepieces would do as well.

The optics in your polarizer are there to compensate for the extra tube length that the polarizer contributes. That keeps the length at 160mm. If you were to use objectives with an infinity tube length, you would need to remove those optics from the polarizer, maintaining only the polarizing function.

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