3D vision on a compound microscope???

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smollerthings
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3D vision on a compound microscope???

#1 Post by smollerthings » Wed Oct 27, 2021 6:14 pm

Hi everyone,

I just got a Ba310 a couple of days ago. And I noticed today... and I know is it not possible on a compound microscope so I am aware this is crazy... I can see the slide in 3D? I can see the different layers of the slide. When I slightly move my eyes from left to right, the foreground move vs the background. The upper portion vs the lower. I can see distinctively the coleps swim UP AND DOWN the slide along the Z axis. And it is beautiful.

Works for 4x, 10x, 20x.

This didn't happen until I played with the diopters on the eye pieces.

How is that possible with both eyes getting info from the same objective?

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Re: 3D vision on a compound microscope???

#2 Post by smollerthings » Wed Oct 27, 2021 8:29 pm

I think I got it.

I noticed the depth effect is stronger when both eye tubes are closer together. I think what is happening is that both eyes get different images because they are both off axis. One to the left, the other to the right. The more off axis, the stronger the 3D effect. I suspect it works better on high relief eye pieces.

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Re: 3D vision on a compound microscope???

#3 Post by patta » Thu Oct 28, 2021 7:43 am

Possible indeed, and your explanation sounds right.

Low-magnification objectives have large "exit pupil" , and the two pupils can crop it, so effectively restrict the light beam, and each eye sees a different"direction". This is done at the expenses of NA. As you noticed, it works when the distance between the eyepieces does not match the eyes distance; so the eye is off-axis and you see the object "from the side".

In practice is like using the compound microscope objective like the one from a CMO stereomicroscope.

I had the dream some time ago to use this pupil trick to make 3D scanning, maybe.

Some drawing would help to understand the trick.

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Re: 3D vision on a compound microscope???

#4 Post by smollerthings » Thu Oct 28, 2021 9:34 am

I think this will help.
3D effect.jpg
3D effect.jpg (34.69 KiB) Viewed 6102 times

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Re: 3D vision on a compound microscope???

#5 Post by smollerthings » Thu Oct 28, 2021 9:42 am

patta wrote:
Thu Oct 28, 2021 7:43 am
I had the dream some time ago to use this pupil trick to make 3D scanning, maybe.
I think that is a great idea. And it would be really cheap and adaptable on existing equipment.

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Re: 3D vision on a compound microscope???

#6 Post by Adam Long » Fri Nov 12, 2021 10:13 am

Interesting.

There is a similar phenomenon known to users of binoviewers on astronomical telescopes. Of course it is not possible to see astronomical objects in 3-d in real-time as they are too far away. But by sightly changing the focus of one eye, or slight mismatch of zoom eyepiece focal length, an impression of 3-d can be created. Some manufacturers even sell eyepieces which generate an artificial 3-d effect with an array of lenses. https://www.cloudynights.com/topic/6482 ... =+3#8208d=

I wonder which mechanism is operating here, perhaps both?

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Re: 3D vision on a compound microscope???

#7 Post by patta » Fri Nov 12, 2021 11:52 am

Here, it is "almost true" 3D
the object is seen from the side as the aperture is "stopped" by the eye iris so it becomes oblique; and each eye sees from an oblique point of view.
Objects out of focus appear shifted on the side because, we have cropped their bokeh ball.
More or less the same as oblique illumination
Also in order to peek in the eyepieces, the eyes are converging (see drawing above) so our brain thinks "near, 3D"

Not truly true 3D as projection and focus planes are still the same.

The stereo microscopes, I think do something similar, and when the perspective-convergence-aperture combination isn't right, we see unnatural 3D effects like the "doming"

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Re: 3D vision on a compound microscope???

#8 Post by Chas » Fri Nov 12, 2021 4:12 pm

Semicircular eyepiece caps 640.jpg
Semicircular eyepiece caps 640.jpg (35.95 KiB) Viewed 5924 times
They fit over the eyepeices to give stereovision
The semicircular hole sits about 8mm plus 1.5mm above the eyepeice edge on the lower powers. The one for high powers sits 4mm plus 1.5mm (The 1.5mm how much roughly the viewing hole is raised above its surrounds )

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Re: 3D vision on a compound microscope???

#9 Post by PeteM » Fri Nov 12, 2021 5:23 pm

One stereo microscope maker (Leica is my recollection) makes a pricey scope with one eye path sharply in focus and the other set for greater depth of field. Or something like that - I've never seen or imagined being able to justify the price of one.

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Re: 3D vision on a compound microscope???

#10 Post by smollerthings » Fri Nov 12, 2021 6:10 pm

Chas wrote:
Fri Nov 12, 2021 4:12 pm
They fit over the eyepeices to give stereovision
The semicircular hole sits about 8mm plus 1.5mm above the eyepeice edge on the lower powers. The one for high powers sits 4mm plus 1.5mm (The 1.5mm how much roughly the viewing hole is raised above its surrounds )
Amazing, never saw those!

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Re: 3D vision on a compound microscope???

#11 Post by microEYE » Fri Nov 12, 2021 8:07 pm

This is fascinating! How could you adapt an existing microscope?

Could you then use cameras?

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Re: 3D vision on a compound microscope???

#12 Post by smollerthings » Fri Nov 12, 2021 8:33 pm

microEYE wrote:
Fri Nov 12, 2021 8:07 pm
This is fascinating! How could you adapt an existing microscope?
Nothing. On my Motic Ba310, the effect appears when the eye pieces are closer to each other than optimal. They are N WF 10x/20 mm. Works for the 4x until the 20x. Infinity optics. I would think it works on many other microscopes?
microEYE wrote:
Fri Nov 12, 2021 8:07 pm
Could you then use cameras?
To capture the effect and project it, I think you would need 2 cameras mounted off axis and a VR device. May be tricky but it would be so interesting to know if this actually works.

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Re: 3D vision on a compound microscope???

#13 Post by patta » Sat Nov 13, 2021 2:04 am

Nice! I've tried to make those caps to stop down the eyepiece aperture last week, but it didn't work well;
needs to be precise; and then you have to squint the eye against it
.
Exit pupil stop cap
Exit pupil stop cap
20211113_025707~2.jpg (123.71 KiB) Viewed 5848 times

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Re: 3D vision on a compound microscope???

#14 Post by smollerthings » Sat Nov 13, 2021 10:16 am

patta wrote:
Sat Nov 13, 2021 2:04 am
Nice! I've tried to make those caps to stop down the eyepiece aperture last week, but it didn't work well;
needs to be precise;
Are you using PETG? Those tend to string and it is hard to be precise with it. You need to sand it down after.

Do you perceive the effect without the stop?

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Re: 3D vision on a compound microscope???

#15 Post by Chas » Sat Nov 13, 2021 10:31 am

Patta, what is the idea behind stopping down the eyepiece's aperture ??
If it helps with the fabrication of stuff; the stereo caps have a kind of ledge inside them so that they come to rest at the right distance above the eyepeice
Back of eyepeice caps.jpg
Back of eyepeice caps.jpg (29.4 KiB) Viewed 5819 times
I have read that the stereo caps are supposed to go where the Ramsden disc lies , which I presume is the narrowest/ sharpest area of light that comes out of the eyepeice (?)
[But I have also read that they cannot really go there as that coincides with your eye's pupil... so there's maybe a fudge involved].

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Re: 3D vision on a compound microscope???

#16 Post by smollerthings » Sat Nov 13, 2021 12:26 pm

@Chas

How does those stereo caps change your experience vs no caps? What eye pieces do you use them on?
Last edited by smollerthings on Sat Nov 13, 2021 2:45 pm, edited 1 time in total.

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Re: 3D vision on a compound microscope???

#17 Post by Chas » Sat Nov 13, 2021 2:09 pm

Smollerthings, I actually purchased these things as a curiosity, but when I got them they didnt fit over the eyepeices that I had on my binocular microscope, so I forgot about them until I saw this post.
Since that time I have acquired a couple more microscope bits and in particular some attachable binocular heads... so I have just started playing with them now, again.
To be honest I dont bother with binocular microscopes but when I do I find that using your trick of altering the interoccular distance does give a nice and sometimes very useful stereoscopic view.
( Out of interest; the stereo eyepeice caps have been in existence for a very long time; Ernst Abbe wrote about them)

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Re: 3D vision on a compound microscope???

#18 Post by smollerthings » Sat Nov 13, 2021 4:02 pm

Chas wrote:
Sat Nov 13, 2021 2:09 pm
To be honest I dont bother with binocular microscopes but when I do I find that using your trick of altering the interoccular distance does give a nice and sometimes very useful stereoscopic view.
Nice :) Do you notice a big improvement of 1/ smaller inter-ocular distance with the stereo caps over 2/ smaller inter-ocular distance without the stereo caps?

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Re: 3D vision on a compound microscope???

#19 Post by patta » Sat Nov 13, 2021 7:44 pm

those caps, I wanted to make them so to play stopping down the "Ramsen disk" also known as eyepiece exit pupil.
It should have the same effect as installing a stop in the objective's aperture; like a funnel; but often (Plan objectives) it is not possible.

intended for photography, but now thanks to Chas we know that have also an old story for visual use.

Just published the design for those caps, simple but customizable for your eyepiece diameter
Yes with a flange that stops at a certain distance
https://www.thingiverse.com/thing:5136258
Printing them now with PLA, with the half-stop.
Heaps of objective funnels coming next.

I think those caps can work also if not exactly precisely at the Ramsden disk position (or, the eye can be a bit off too). Let's see!

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Re: 3D vision on a compound microscope???

#20 Post by patta » Sun Nov 14, 2021 12:59 pm

Print didn't work so well, but anyway, I have the two "stereo caps". Semi-transparent blue :?
Hard to use, I think will be better to have them about 1-2 millimeter lower than the eyepiece aperture / Ramstein disk
Also the half-cut needs to be in the dead center within less than 0.5mm, or no effect.

Below a crude photo of the effect; left and right; afocal phone camera where the eyes should be.
The effect seems to be Oblique illumination, with each eye :geek: getting oblique from different direction
Maybe other subjects will look more 3D
Not sure whether the opening should be inside or outside?

Edit: oh btw more or less the same effect can be obtained by keeping the phone camera off-center, so the camera aperture stop takes just a side of the Ramdsen disk; like does the eye stop (iris) of post #4
.
Half moon caps
Half moon caps
20211114_141759.jpg (66.81 KiB) Viewed 5718 times
.
Pseudo stereo images  - L & R maybe swapped
Pseudo stereo images - L & R maybe swapped
Photo_left_right.jpg (50.12 KiB) Viewed 5726 times

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Re: 3D vision on a compound microscope???

#21 Post by smollerthings » Sun Nov 14, 2021 2:54 pm

Interesting. The 3D effect I see seems to be independent of any oblique illumination :geek:

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Re: 3D vision on a compound microscope???

#22 Post by Chas » Sun Nov 14, 2021 4:38 pm

Hmm, well I can confirm that getting these caps in exactly the correct position on an eyepeice is tricky++ /near impossible :-(
Funnily enough some heads do seem to give a stereo effect quite naturally at x60 (x10 objective x6 eypeices) and the caps do not seem to add to or enhance this depth effect.
I dont think it would be reasonable to expect our grey matter to be able to magic up a stereo image when such a thin slice of what it is looking at is in focus and it seems hard to notice a stereo effect with a x40 objective, but maybe if I looked at a tiny feature I might see it (yet to try though).
Maybe these caps were designed to solve a problem that doesn't exist today; we can pick up an old Greenhough off ebay for not much, back then such a thing was not possible.
I am not sure that anything could now beat the synthetic-stereo images produced by focus-stacking programs, I have just tried this at x400 on a mounted insect antenna and the stereo image produced was magical.
patta, I like those slots that you have printed ..I have just started with a printer and so far nothing has fitted quite as tighly as I would like .... with slots I might be able to print things slightly wrong and then get a push fit (?)

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Re: 3D vision on a compound microscope???

#23 Post by patta » Sun Nov 14, 2021 5:47 pm

maybe was just a blunder, the 3D effect does not come from stopping the aperture?
Anyway those caps are a pain to use, squint the eyes against them, then dizziness an headache...

Yes the slot cuts make the plastic a bit flexible so the press-fit more or less work. The cap can also be "massaged" to get in the right position.
3D printed parts usually come out a bit smaller than designed, like 0.2mm or some 1%, so if the dimension was for exact fit, the piece will be too tight.
Those caps are designed with diameter 0.6mm smaller than the eyepiece (build, ~0.8mm), and they manage to flex and fit ok.

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Re: 3D vision on a compound microscope???

#24 Post by Chas » Tue Nov 16, 2021 1:37 pm

Apparently...i.e. from a book; when both the innermost sides are blocked, you get a stereoscopic effect and when both the outermost sides are blocked by the caps you get a "pseudoscopic" effect , which I guess is an inverted stereo

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Re: 3D vision on a compound microscope???

#25 Post by apochronaut » Tue Nov 16, 2021 1:55 pm

The last post is correct . By increasing the width of the ocular tubes, which is the same as having those half moon ocular shields with the innermost sides blocked you get a degree of stereo. By decreasing the ocular width or the same as having the outermost sides blocked the stereo effect reverses and details in height become details in depth and visa versa.
This is a well known optical effect in microscopy but little used. Jentsch heads that apply parallax due to placing the eyetubes at an angle of convergence enhance this effect and make it little easier but the effect can take place fairly easily with wider field heads that have parallel tubes.

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Re: 3D vision on a compound microscope???

#26 Post by josmann » Wed Jan 26, 2022 8:48 pm

Chas wrote:
Sun Nov 14, 2021 4:38 pm
Hmm, well I can confirm that getting these caps in exactly the correct position on an eyepeice is tricky++ /near impossible :-(
patta wrote:
Sun Nov 14, 2021 5:47 pm
maybe was just a blunder, the 3D effect does not come from stopping the aperture?
Anyway those caps are a pain to use, squint the eyes against them, then dizziness an headache...
Y'all might want to check out this video I just made. I think you'll find Shinya's approach much more palatable for extended viewing :)

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