Olympus BH2 BHSP with reflected light

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woyjwjl
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Re: Olympus BH2 BHSP with reflected light

#31 Post by woyjwjl » Thu Dec 15, 2022 6:28 am

microcosmos wrote:
Sun Oct 02, 2022 6:11 am
PeteM wrote:
Sat Oct 16, 2021 3:10 am
It might also be interesting to try a full UIS-infinity-compatible conversion. I don't know much about the polarization analyzer, but I'd assume the tube lens in another f=180 epi head could be removed and then something like a U-TLA tube lens added in place of a trinocular head for direct imaging to a camera. Cost, at least on US ebay, would be around $200 for a spare epi head and a U-TLA tube lens. The glitch would be that costly analyzer. If it's a finite type, the matching lens would have to be (carefully) pulled out to give this a try. If simple polarization is all that's needed for the photos, a good extinction polarizer could probably be fitted under the U-TLA -- just removing the analyzer.
The time has come. I'm now considering this full UIS-infinity-compatible conversion that Pete suggested, and it is actually not that difficult as long as the appropriate parts are CAD-designed and CNC machined.

This is the plan:

- remove the existing BH2-era tube lens from the MA2 epi-illuminator. This is simple - just unscrew the upper part of the epi-illuminator, which holds the tube lens, and ditch it.
- design and machine a connecting dovetail to connect the bottom of the analyzer assembly to the top of what remains of the epi-illuminator.
- remove the finite matching lens of the analyzer assembly. We thought this was going to be tricky but actually it's not - the mount holding the lens is actually just screwed onto the rest of the analyzer assembly, so all I have to do is to unscrew it! And machine a replacement mount without the lens, as the mount also contains the female dovetail connector needed to connect stuff above the analyzer.
- machine a dovetail mount to take the SWTLU tube lens, which is sold individually with a M41 threaded mount. Stack this tube lens assembly on top of the analyzer assembly.

And on top of the new tube lens goes the trinocular head, and it's done. The one thing I'm not yet sure of is whether the 151.3 mm focal length of the new tube lens matches distance to the eyepieces of the BH2 head.

I would be grateful for any advice.
This is an interesting job. I happen to have similar equipment

I'm just a pure hobby, so I can't give you any useful advice

But please let me bother you with a few questions

1. Is the tube lens of "MA2 epi illuminator" (RLA) green or red?
1.png
1.png (149.8 KiB) Viewed 3272 times
2. Since the focal length is 180mm, is there any difference between "BH2 era tube" and "SWTLU tube"? Why replace it?

3. I think "fine matching lens" is only used to compensate the pipe length. Why should it be removed?

4. What interests me most is, before that, was the working distance of your UIS objective lens (greater than 40 times) normal?
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microcosmos
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Re: Olympus BH2 BHSP with reflected light

#32 Post by microcosmos » Sat Dec 17, 2022 2:21 am

1. Does your diagram show MA2 or RLA? You said ""MA2 epi illuminator" (RLA)" so I'm not sure which one you're talking about. My MA2 doesn't have the lens with the red arrows. It is missing the entire AB119800. I assume my tube lens is the green one.

2. Yes, the tube lens has different corrections for different-era objectives.

3. What is the "fine matching lens"? I can't find a reference to it anywhere in the thread.

4. The working distance was normal before and after all the modifications I have made so far.

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Re: Olympus BH2 BHSP with reflected light

#33 Post by woyjwjl » Sun Dec 18, 2022 4:05 pm

microcosmos wrote:
Sat Dec 17, 2022 2:21 am
1. Does your diagram show MA2 or RLA? You said ""MA2 epi illuminator" (RLA)" so I'm not sure which one you're talking about. My MA2 doesn't have the lens with the red arrows. It is missing the entire AB119800. I assume my tube lens is the green one.

2. Yes, the tube lens has different corrections for different-era objectives.

3. What is the "fine matching lens"? I can't find a reference to it anywhere in the thread.

4. The working distance was normal before and after all the modifications I have made so far.
1. RLA,The lens part should be the same as RLA. Are you sure? AB119800 is Analyzer slider,Please ignore it。
_20221218235624.jpg
_20221218235624.jpg (154.45 KiB) Viewed 3168 times
2.If it's just CA correction, I don't think it's necessary

3.finite matching lens

4. Confusion....."doesn't have the lens with the red arrows" :?:
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Re: Olympus BH2 BHSP with reflected light

#34 Post by microcosmos » Sat Dec 24, 2022 4:24 am

1. I am quite sure my MA2 doesn't have the red arrow lenses. Maybe they belong to the analyzer slider above, or maybe the lenses were removed for some reason before I acquired the part.

2. Why don't you think it's necessary?

3. Ok, but where is it in the diagram? Is it just another name for the tube lens? Sorry for my ignorance.

4. See my answer to 1.

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Re: Olympus BH2 BHSP with reflected light

#35 Post by woyjwjl » Sat Dec 24, 2022 4:39 pm

microcosmos wrote:
Sat Dec 24, 2022 4:24 am
1. I am quite sure my MA2 doesn't have the red arrow lenses. Maybe they belong to the analyzer slider above, or maybe the lenses were removed for some reason before I acquired the part.

2. Why don't you think it's necessary?

3. Ok, but where is it in the diagram? Is it just another name for the tube lens? Sorry for my ignorance.

4. See my answer to 1.
1.I think this is.
Olympus microscope BH2-MA-2 vertical illuminator tube lens anti reflective flocking-L.jpg
Olympus microscope BH2-MA-2 vertical illuminator tube lens anti reflective flocking-L.jpg (80.35 KiB) Viewed 3087 times
2.The chromatic aberration is corrected in the eyepiece, not here

3.The BH2 fluorescent objective lens is finite far. The middle tube lens of the fluorescent kit is used to compensate the tube length

So, I think red and green lenses have different uses. If you are mistaken
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Re: Olympus BH2 BHSP with reflected light

#36 Post by microcosmos » Sun Dec 25, 2022 5:34 am

1. I think this is the green lens, not the red lens. You are looking at it upside down.

2. Ok I understand. But why did the other members of the forum suggest changing the tube lens? Perhaps the tube lens does correct something that is different between BH2 and UIS2 optical systems?

3. What does "finite far" mean? What does "middle tube lens" mean? I thought there's only one tube lens (which I assume can be doublet/triplet etc.), no bottom/middle/top etc.

I am sure the green and red lenses have different uses. But as mentioned, I don't have the red lenses.

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Re: Olympus BH2 BHSP with reflected light

#37 Post by Scarodactyl » Sun Dec 25, 2022 6:26 am

microcosmos wrote:
Sun Dec 25, 2022 5:34 am
Perhaps the tube lens does correct something that is different between BH2 and UIS2 optical systems?
Yes. It might not matter much with normal eyepieces though--with ultrawide eyepieces or an aps-c format camera it has effects in the corners.
Last edited by Scarodactyl on Sun Dec 25, 2022 5:29 pm, edited 1 time in total.

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Re: Olympus BH2 BHSP with reflected light

#38 Post by woyjwjl » Sun Dec 25, 2022 2:16 pm

microcosmos wrote:
Sun Dec 25, 2022 5:34 am
1. I think this is the green lens, not the red lens. You are looking at it upside down.

2. Ok I understand. But why did the other members of the forum suggest changing the tube lens? Perhaps the tube lens does correct something that is different between BH2 and UIS2 optical systems?

3. What does "finite far" mean? What does "middle tube lens" mean? I thought there's only one tube lens (which I assume can be doublet/triplet etc.), no bottom/middle/top etc.

I am sure the green and red lenses have different uses. But as mentioned, I don't have the red lenses.
That is to say, you lack the whole AB138900 (INNER PLATE)? However, your infinity objective works normally? :shock:

I have a bold guess. :idea: The AB138900 (INNER PLATE) should not exist with the green lens at the same time. It is equipped with a limited far objective lens, just to compensate the tube length
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Re: Olympus BH2 BHSP with reflected light

#39 Post by microcosmos » Mon Dec 26, 2022 3:45 am

microcosmos wrote:
Thu Oct 14, 2021 3:49 am
Image
I have what I think is the AB138900 inner plate as shown in the photo above. But it is just an empty ring, no glass in it. My infinity objectives seem to work, although the CA is not fully corrected presumably partly because I am using BH2 eyepieces with UIS2 objectives.

I use ultrawide (26.5) eyepieces so maybe the tube lens will make a difference. My objectives are all 26.5.

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Re: Olympus BH2 BHSP with reflected light

#40 Post by Scarodactyl » Mon Dec 26, 2022 5:24 am

I found when using mitutoyo m plan apo objectives on a bh2-uma tube lens I got distorted corners which did not appear on the neo splans it was meant for. Uis/uis2 objectives will suffer similarly, and that's without the addition of the bh2 era eyepiece corrections which are strong enough to add significant CA to unmatched objectives.

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Re: Olympus BH2 BHSP with reflected light

#41 Post by microcosmos » Thu Dec 29, 2022 11:48 am

What do you mean by distorted corners? Do you mean pincushion/barrel distortion near the corners? I didn't notice anything with my UIS2 objectives and FN26.5 BH2 eyepieces, but I wasn't looking very hard and I wasn't looking at a grid.

Indeed, the mix of UIS2 objectives, BH2 tube lens and BH2 superwide eyepieces on my microscope is not optimal, as discussed earlier in this thread. As explained in detail previously, I arrived at this configuration for various other reasons.

Although I appreciate the true plan apo images I get from correctly configured microscopes in research labs I have worked in, I am actually not bothered by the CA on my microscope. That's because it has given me so much in spite of the CA.

It has enabled me to study the petrography of rocks in my country and make quantitative birefringence measurements, which very few people here have done and very few instruments here can do. It has enabled me to metallographically determine the composition of the eutectic tin-lead alloy in an organ pipe, which could be useful in the restoration of historic pipe organs but which has rarely if ever been employed as a method to accurately analyse organ pipe alloys. I have used the microscope to compile a collection of bird feather barbule substructure micrographs that could be used to identify species from feathers, which to my knowledge not even the natural history museum in my country has done.

Of course, there are applications where CA has to be completely corrected, but the instrument has nevertheless proven capable of producing serious research output. The insights and fun it has given me have massively outweighed the CA and the other minor optical issues described earlier in the thread. Not to mention that it makes an awesome Zoom virtual background, towering over me like a Saturn V.

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Re: Olympus BH2 BHSP with reflected light

#42 Post by Scarodactyl » Thu Dec 29, 2022 4:12 pm

I am honestly not certain what type of distortion it was, it was years back. I imagine I still have some pictures somewhere.
Your setup's obviously working and giving good results, these notes are more a hypothetical if you ever want to tweak things further. When I had a similar setup I eventually did want to adjust things more which is why I mention it, but you might never feel the need.

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Re: Olympus BH2 BHSP with reflected light

#43 Post by microcosmos » Sun Jan 15, 2023 5:07 am

Here are test images of illumination uniformity, taken in transmitted and reflected light with the 4x objective (FN26.5) and an EOS-1D X DSLR and NFK 2.5x photo eyepiece.

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Transmitted light, Köhler illumination

Screenshot 2023-01-15 at 11.13.38.png
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Intensity profile of transmitted-light image along the SW-NE diagonal. Note that the 16-bit intensity values range from 57000 to 61000, so actually the illumination is quite even although the graph shows a big hump.

Screenshot 2023-01-15 at 11.09.24.png
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Reflected light, Köhler illumination, reflecting off the silver-coloured back surface of the test slide detailed here.

Screenshot 2023-01-15 at 11.09.57.png
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Intensity profile of reflected-light image along the SW-NE diagonal. I am quite happy with how flat it is.

Screenshot 2023-01-15 at 11.14.13.png
Screenshot 2023-01-15 at 11.14.13.png (97.16 KiB) Viewed 2775 times
Centering the episcopic lamp filament on the BH2-MLSH lamp house, using the Bertrand lens. At 4x the filament length already fills the entire diameter of the back focal plane of the objective.

Anyone else measured your illumination? How does my microscope compare?

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Re: Olympus BH2 BHSP with reflected light

#44 Post by Scarodactyl » Sun Jan 15, 2023 5:37 am

Seems quite good! I haven't measured my Nikon system but the corners are definitely visibly darker on aps-c.

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