Imaging Whole Geological Subjects - What Micro Setup?

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heyitsmedusty
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Imaging Whole Geological Subjects - What Micro Setup?

#1 Post by heyitsmedusty » Thu Jul 14, 2022 8:37 pm

TLDR; what would you propose as a decent setup to outfit my Olympus CH-2 (realistic, let's say <$1000) to get high quality photos of solid subjects 0.2mm-0.4mm? Reflected light, lots of surface texture. Looking for suggestions on objectives that will work with the CH-2 stand, suggestions on lighting, and suggestions on the best way to adapt my Canon 6D DSLR to the microscope.
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I have been digging through these forums and already learning so much, but I haven't found a definitely guide to the kind of photography I am hoping to do through my microscope yet, so I'm hoping you can help!

I search for and photograph micrometeorites in dust samples. They are generally 200um-400um in size (all the way around, since they are generally spheroid), and they are generally opaque, although they are sometimes translucent. They require strong diffused reflected light to capture the texture of the surface.

For imaging, I currently use an Olympus CH-2 scope with a trinocular head. My camera is a full frame Canon 6D, which I attach to the Olympus with an Omax 2x adapter (23.2). I have also done some afocal projection to a 100mm macro lens, and direct-to-sensor projection with no adapter or lens attached (which is indeed a bit scary).

I have been experimenting with lots of different lighting techniques, including large light sources, small diffused light sources, and subject-surrounding diffusers like sliced up ping-pong balls with bright lights directed at them. I have gotten some interesting results, but I think the setup can be improved substantially. I have been using the crappy "E" series Olympus objectives that came with the microscope, but there must be better options out there. I'm thinking a longer working distance would be good to maximize the amount of light reaching the subjects, and corrections for chromatic aberration.

Any and all help is appreciated! Thank you!

heyitsmedusty
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Re: Imaging Whole Geological Subjects - What Micro Setup?

#2 Post by heyitsmedusty » Sun Jul 17, 2022 4:39 am

Would long working distance objectives help me get more light around the subjects?

PeteM
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Re: Imaging Whole Geological Subjects - What Micro Setup?

#3 Post by PeteM » Sun Jul 17, 2022 5:52 am

At least here in the Bay Area, half your budget might get you a proper reflected light microscope with longer working distances. There's little to be gained, in my opinion, to try to adapt your CH2 stand.

While it could be used, it will require an epi illuminator, probably polarizers, a new illuminator, and a new set of MPlan objectives. Your current objective are meant to be used with a cover slip - and won't perform well with through-the-lens epi illumination.

It will be cheaper and better just to buy a complete scope IMO. While Olympus made these scopes (e.g. BHM), Nikon versions are a worthy and sometimes superior alternative. For a just a little bit more (still well under your budget) you might even get one capable of both polarized and darkfield epi illumination. You'll have enough working distance at lower magnifications to bring in light from the side and have reflected through-the-objective illumination at all magnification. Polarization can cut reflections and provide more detail. Darkfield can show surface textures.

heyitsmedusty
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Re: Imaging Whole Geological Subjects - What Micro Setup?

#4 Post by heyitsmedusty » Mon Jul 18, 2022 5:06 pm

@peteM, great advice, thank you!

I'm now looking into Olympus BHM microscopes. Are there other models you would recommend? I am also looking up "metallurgical microscopes" in general, but there are so many listings where the sellers don't really know that the microscope they are selling was intended for metallurgical use, so they just post the model number.

For the BHM, does it have infinity correction built in, or is it finite? Or do I need a component to use infinity-corrected objectives?

PeteM
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Re: Imaging Whole Geological Subjects - What Micro Setup?

#5 Post by PeteM » Mon Jul 18, 2022 5:48 pm

I've seen BHM microscopes with both short barrel Olympus "Neo" objectives and long barrel infinity MDPlan or MSPlan objectives. These older finite ones are pretty good and should be cheaper and will need the objectives and illuminator to be a match due to the much longer tube length.

The next Olympus generation has infinity objectives marked "f=180" for the reference tube length. Like the earliest short barrel epi objectives, there are plain epi versions and darkfield (e.g. NeoDplan and NeoSPlan) versions with the same central optics but a channel on the outside for a circle of light to be projected down on to the specimen for darkfield.

In the F=180 infinity versions the MDPlan and MSPlan (or darkfield Neo versions) represent levels of optical quality, with MSPlan having better quality, a wider field of view, and suitability for reflected DIC.

In these long barrel infinity version (marked "F-180" for the reference tube length), the epi illuminator includes a lens to allow these "F=180" objectives to be used with the regular Olympus BH2 finite heads. BH heads will also fit but have a narrower field of view, better suited to the earlier short barrel versions.

More recent Olympus models used different infinity objectives and a more standard tube lens built into the head. The corrections are different and you don't want to use the "f=180" objectives to get best results with the most recent Olympus reflected microscopes.

Nikon epi/metallurgical microscopes can be somewhat similarly confusing. Their "chrome free" optics can be a plus in hooking up cameras. Their plastic fine focus gears may need replacing (easy, not too expensive). They have both 210mm parfocal finite versions and a couple different infinity versions, with similar options in the illuminators and objectives for brightfiled, polarization, darkfield, and DIC reflected methods. "Microscope Mike" has a site at the U. of Arizona that could be a help in sorting things out: https://lavinia.as.arizona.edu/~mtuell/index.html

One approach is to find a seller who either has a complete original microscope or who knows what they're doing. Letting us know your location can help find someone to help. Were you in the Bay Area and willing to help with our "Micronaut" program that could be me. Someone like member "Scarodactyl" is super knowledgeable about gem/geological specimens and might have a suitable scope for sale if you were on the East Coast of the US.

Another approach is to do some homework and wait for what you believe is a bargain and then figure out what parts may be missing or mismatched and complete the scope. If going the latter approach, find the relevant Olympus or Nikon brochure and inspect the scope to see if things are a match.

Good luck. Epi illumination is very cool. There are excellent scopes out there well under your $1K budget.

heyitsmedusty
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Re: Imaging Whole Geological Subjects - What Micro Setup?

#6 Post by heyitsmedusty » Mon Jul 18, 2022 7:34 pm

Pete, this is all incredibly helpful.

I'm located in Kentucky, so most of my searching is on eBay. I'm up for putting together a bargain system based on the appropriate parts. I have been referencing this brochure to sort out the various components I might/will need to get a fully working reflected light setup: http://www.alanwood.net/downloads/olymp ... ochure.pdf

So a couple questions:

1. If I get an Olympus BHM stand, and it is outfitted with an illuminator between the nosepiece and the head, are you saying it will work with f=180 objectives as well as infinity corrected objectives?
2. Is the light which is transmitted from the illuminator down through the channels in the objectives good for photography? Are there examples online of the images this produces?

Thank you again, this is so helpful. I'm learning, quickly!

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Re: Imaging Whole Geological Subjects - What Micro Setup?

#7 Post by PeteM » Mon Jul 18, 2022 8:05 pm

The "f=180" objectives and illuminators (as shown in the linked brochure) are the earliest Olympus infinite system. The f=180 is the "reference tube length" of 180mm.

You have to be careful in buying a BHM off Ebay to be sure that it isn't fitted with the earlier style illuminator. Those don't have an infinity correcting lens inside and have to be matched with the proper no-cover-slip objectives. As seen in the brochure you linked, the illuminator you want should have the "f=180" marking at the front. You then have to be careful to get the right objectives to go with it.

If you already have something like a BH2 trinocular head, you can use it with this system. Your CH2 head should work, too, but with a narrower field of view. There is a tube lens in epi illuminator designed to match the (MDPlan, MSPlan, NeoMDPlan, NeoMSPlan) objectives to regular BH/BH2 finite heads. That illuminator and its tube lens won't be quite right for other infinity objectives.

A complete system like this, with polarization and possibly darkfield, should be a bit under $1K depending upon which objectives and options are included. Buying parts a few at a time may cost more - the shipping and taxes add up and the last elusive bit always seems either a very long wait or $$$.

The earlier system, often found on gray-painted Olympus epi scopes and sometimes on early BHM models might be more like $500 if you find one complete and in good shape. Those illuminators, coupled with the proper Neo and M objectives, also allow the use of regular finite heads, such as may have come with your CH2.

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Re: Imaging Whole Geological Subjects - What Micro Setup?

#8 Post by heyitsmedusty » Wed Jul 20, 2022 3:21 pm

So if I added this f=180 illuminator box under my current CH2 binocular head, would I be able to use the "M" objectives (or any objective with "f=180")?

https://www.ebay.com/itm/265759527687?h ... SwEwViqAu7

PeteM
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Re: Imaging Whole Geological Subjects - What Micro Setup?

#9 Post by PeteM » Wed Jul 20, 2022 4:22 pm

Yes, in principle.

The illuminator you've linked is missing just about everything you'll want or need. No lamp, unsure condition of condensing lens, no brightfield (BF) or darkfield (DF) cubes ($$$), no covers, not sure if it has polarizers.

Your CH2 head will restrict the field of view, but work with a complete illuminator. You're more likely to find a complete black "f=180" illumintor which just does BF and DF epi illumination. The equivalent of "cubes" are built into those. Were your linked illuminator complete, it could also incorporate fluorescent cubes.

Either way be sure to get the metallurgical objectives marked f=180. Olympus made other "M" objectives that won't work.

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Re: Imaging Whole Geological Subjects - What Micro Setup?

#10 Post by blekenbleu » Wed Jul 20, 2022 11:18 pm

If you have space, consider getting another microscope that already has EPI illumination.
Nikon seems to have sold more, at least in the U.S., e.g. for semiconductor inspection, than Olympus.
I like BD Plan objectives typically found on Optiphot-66; their coaxial illumination can be quite nice.
They need no additional correction, so can focus directly to a camera sensor.
However, Canon EF DSLR flange-to-sensor distance confounds that for Nikon trinocular heads,
but Nikon's CF PL2.5 photo relay lens is relatively common.

Of course, there are also new metallurgical microscopes for < US$1000.
Metaphot, Optiphot 1, 66; AO 10, 120, EPIStar, Cycloptic

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Re: Imaging Whole Geological Subjects - What Micro Setup?

#11 Post by heyitsmedusty » Fri Sep 02, 2022 6:20 pm

Thanks for everyone's help so far!

Just to close the loop for now, I ended up putting a BH2-MA vertical illuminator (only brightfield capabilities) on the CH-2 stand, and purchased some MSPlan objectives to complement. I installed an LED light source to replace the halogen lamp.

And I'm getting some great photos so far! Here are some examples of micrometeorites I have imaged with this setup:

Cryptocrystalline Micrometeorite, 180um, Olympus MSPlan 50x, NFK 3.3x photo eyepiece, Canon 6D
CC-165x.jpg
CC-165x.jpg (149.75 KiB) Viewed 2462 times
Micrometeorite candidate, 150um, Olympus MSPlan 50x, NFK 3.3x photo eyepiece, Canon 6D
candidate-165x.jpg
candidate-165x.jpg (346.94 KiB) Viewed 2462 times

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Re: Imaging Whole Geological Subjects - What Micro Setup?

#12 Post by blekenbleu » Fri Sep 02, 2022 9:24 pm

Playing with a polarizing filter, analyzer and perhaps wave plates should help tame those specular reflections.
Metaphot, Optiphot 1, 66; AO 10, 120, EPIStar, Cycloptic

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Re: Imaging Whole Geological Subjects - What Micro Setup?

#13 Post by Scarodactyl » Fri Sep 02, 2022 10:36 pm

Congrats on the setup! Looking good so far.

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Re: Imaging Whole Geological Subjects - What Micro Setup?

#14 Post by heyitsmedusty » Tue Mar 28, 2023 7:10 pm

Just wanted to post an update here on the setup I ended up with --

Stand: Olympus BH
Head: Olympus BH trinocular
Attachments: BH2-UMA vertical illuminator, trinocular port adapter w/ NFK 2.5x
Objectives: Olympus LMPlanFL 20x/0.40 Bd, Nikon CF Plan 40x/0.65 BD (outer barrel removed), LWD NEOSPlan 50x/0.55

The vertical illuminator allows me to use infinity corrected optics. The photo eyepiece isn't ideal for the objectives other than than the NEOSPlan, but I did a few tests and I didn't see much of a difference in chromatic aberration. I'm still doing plenty of color correction in Lightroom, so moving a few more sliders hasn't been a big deal so far. Image attached to show my progress so far!

Right now I'm mainly looking for high magnification objectives with long working distances and high n.a., but they are hard to find.
v-type-small.jpg
v-type-small.jpg (91.38 KiB) Viewed 1772 times

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Re: Imaging Whole Geological Subjects - What Micro Setup?

#15 Post by heyitsmedusty » Tue Mar 28, 2023 7:12 pm

Also as a note, I don't use the vertical illuminator for my lighting. I crafted a very small ring light + diffuser that mounts to the objective for even lighting around the subject. You can see the rings of light reflected in the image above, like the objective looking into a dark mirror.

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