PUMA 3D Printed Microscope

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PJT
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PUMA 3D Printed Microscope

Post by PJT »

Hello and thanks to all FreeCAD developers and supporters for making it possible for me to make the PUMA microscopy system with this excellent software.
It took me 3 years to complete and all my original FreeCAD files are available (under the GPL v3.0) on the PUMA GitHub site for anyone who wants to see the details of how I made any of the parts. There is also a dedicated YouTube channel about the project. Links below.
The PUMA is a professional quality 3D printed open source advanced microscope system.
Attached is a screenshot of one of the mechanisms: It allows the optical tube to quickly attach and detach from the stage of the scope (the 'Quick Release mechanism' or QR mechanism). This showcases the use of FreeCAD to make threads, flexures, ball and socket locks, conical bungs and more. I started on Windows 7 with FreeCAD 0.17 and ended this project on Arch Linux using FreeCAD 0.19.

GitHub
https://github.com/TadPath/PUMA

YouTube Intro Video
https://youtu.be/7UbkrZyNgpo

Even after all this I know I have only scratched the surface of what this software can do.
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Last edited by PJT on Mon Aug 16, 2021 8:03 am, edited 1 time in total.
chrisb
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Re: PUMA 3D Printed Microscope

Post by chrisb »

Interesting project; thanks for sharing.
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M4x
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Re: PUMA 3D Printed Microscope

Post by M4x »

Wow, very.impressive! Thank you very much!
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Kunda1
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Re: PUMA 3D Printed Microscope

Post by Kunda1 »

awesome work!
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PJT
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Re: PUMA 3D Printed Microscope

Post by PJT »

Looks can be deceptive. From the outside the monocular tube of the microscope looks just like a simple tube - but look a little deeper. You will see that I have added a series of specially designed light baffles that have increasing aperture as they travel up the tube.
These are designed to reduce internal reflections from the walls of the tube. The baffles have 45 degree walls so they can be 3D printed without supports. Just another example of how FreeCAD can be used to design high quality optical instruments for FDM manufacture. You can see from the bottom panel the effect - tube on the left is a simple tube, the one on the right has the baffles. This can make a significant improvement to observed image quality.
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keithsloan52
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Re: PUMA 3D Printed Microscope

Post by keithsloan52 »

Just wondering how it compares with https://gitlab.com/openflexure/openflexure-microscope

Apart from the obvious, one was developed with FreeCAD and the other OpenSCAD
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PJT
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Re: PUMA 3D Printed Microscope

Post by PJT »

Openflexure (OF) is great but its main strength is the innovative use of flexure mechanics to make a versatile precision XYZ stage almost entirely from 3D printed plastic parts. It's downside are the rather limited optical abilities and complete dependence on a camera (+ computer + monitor) for making any observations - and that restricts its portability, resolution, field of view and image quality. The flexure stage also has issues - for example flexure movements are in an arc (not a straight line) - so to make the arc approximately linear you need a long radius so you have to balance the bulk and size of the overall scope with the amount of approximation to straight line movement you can tolerate. OF also cannot accommodate bulky observational optics due to its flexure design - this is why it adopts an 'inverted microscope' design and has limited optical abilities. [Yes, there have been a few research papers showing attempts at fluorescence and phase optics but these are relatively impractical and underdeveloped].

PUMA is more about professional quality direct visual optical observations in multiple modalities (ordinary light, polarisation, epi-illumination, fluorescence, Kohler, phase contrast, etc.) combined with ultra-portability and advanced Fourier light processing. PUMA does NOT seek to re-invent the mechanics of a microscope and does not require a Raspberry Pi (or other) camera or computer and screen to make observations so it has superior portability and gives a wide (whole) field of view. PUMA uses traditional linear motion techniques so can deliver a much larger range of motion in XY and Z compared to OF without increasing the bulk of the plastic infrastructure and PUMA's tripost stage can accommodate all the professional and complex optical assemblies required for its advanced features (like trinocular head, augmented reality projector, epi-illuminator, the use of multiple cameras simultaneously, etc.) which would simply not be possible/practicable with a flexure design (like OF). This also allows PUMA to be of traditional 'upright microscope' design.

The issues of software remote control (that are well developed for the OF system) are not relevant because similar robotic control systems could be applied to PUMA if required (the Z axis of PUMA already has a stepper motor option and an XY motor controller is already in development).

There is a lot more that can be said but I refer interested readers to the Journal of Microscopy publication where this comparison is fleshed out with references: https://onlinelibrary.wiley.com/doi/10.1111/jmi.13043
keithsloan52
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Re: PUMA 3D Printed Microscope

Post by keithsloan52 »

PJT wrote: Fri Oct 01, 2021 9:49 am Openflexure (OF) is great but its main strength is the innovative use of flexure mechanics to make a versatile precision XYZ stage almost entirely from 3D printed plastic parts.
My understanding for the motivation behind (OF) being entirely 3D parts was primarily due to the aim for use in third world.
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PJT
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Re: PUMA 3D Printed Microscope

Post by PJT »

Both OF and PUMA use a combination of 3D printing and off-the-shelf components. One key difference - which I would have thought would be advantageous to those in developing countries - is that PUMA can give a complete, instant, wide field of vision with absolute resolution (i.e. resolution and field of view limited only by the user's eyesight) without any electronics at all.
OF, on the other hand, requires the use of a computer, camera and monitor to see anything at all - it is not an option but a necessary requirement. So the quality of what you can see (field of view, resolution, speed of image acquisition, etc.) depends on the quality of your tech equipment (resolution of your camera, physical size and quality of your monitor, etc.) and these need power supplies, etc. - and money for the best quality equipment (and even the most expensive medical grade monitors and cameras are not as good, in terms of resolution and field of view, as direct human vision).
Of course you have the OPTION of capturing images and video with PUMA - but it is just that, an option, not a requirement for seeing anything at all in the first place.
But don't get me wrong, I am not saying PUMA is in any general sense 'better' than OF - they both have their place in the pantheon of 3D printed microscopes - I am just giving my perspective on the differences between the two systems. It would be interesting to hear Prof. Richard Bowman's take on it (the inventor of the OF system).
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PJT
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Re: PUMA 3D Printed Microscope

Post by PJT »

Sorry, in my comparison to other 3D printed microscopes I forgot to mention an important point: PUMA is the only open source 3D printed microscope with an augmented reality (AR) heads-up-display (HUD) module. This is a programmable TFT screen display that is projected and optically superimposed onto the live optical microscope image as seen down the eyepiece - not a digital overlay on a digital camera feed (which is much easier to do - but PUMA was designed to be a quality direct vision optical microscope not limited to camera viewing). All designed in FreeCAD of course and source files are available at the GitHub page: https://github.com/TadPath/PUMA. The image shows the FreeCAD design (top), the 3D printed implementation (below left) and an example of the myriad possible information displays seen when looking down the scope (bottom right). The design allows adjustment of the position of the lenses in the tube to fine tune focus and zoom. It also allowd for X, Y and optical axis angle centration adjustments. A YouTube video on this system will be made in due course. The intro video with some examples is here: https://youtu.be/7UbkrZyNgpo and my Twitter feed gives more snippets: @Paul_Tadrous
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