Wow I’m learning a ton of stuff from your videos concerning optics even though I have zero interest in microscopes. Thanks so much for doing these presentations; they are immensely insightful and well presented.
Thanks. I am planning on doing more videos on diffraction theory, Fourier optics and image processing using the PUMA system as a practical illustration tool with some C programming sessions. So keep an eye on the channel if you are into any of that. A new video will be out this Friday.
This is a great resource for any DIY microscope-optics related projects! Thanks for all the thought and effort put into both the PUMA project and this video.
I come back to say I finally assembled the filter block (with a 20mm half mirror because it was really too hard to adapt for a 30mm one) and it works pretty well with a 5x objective. I don't have a base yet, and I plan to create a totally different design (only for light reflected), so my tests were a little shaky, but the image quality is very good with the 5x objective. Comparable to my metallographic olympus microscope, but very cheap to make, so really well done. This will open up a lot of possibilities. I plan also to make an infrared version because I have a microscope camera with a removable IR cut off filter. I also tried with higher magnification objectives but sadly, the quality deteriorates a lot with very little contrast and a hazy appearance. It may be caused because it's biological objectives (so they requires a coverglass) but I assume it is also because the LED housing don't have any aperture? Any ideas to improve the quality? Did i miss something? Also, do you think it is possible to use dark field with reflected light on PUMA? Or the objectives are the main limitation? (my olympus microscope requires special neo objectives for that purpose + a different vertical illuminator). Thank you! Edit: After some investigation, it's indeed caused by the light reflected from the objective, so even if there is no sample to observe I have a bright image (and therefore a big loss of contrast). If I add a small aperture after the led illumination system it seems to reduces a lot the problem, but it's not perfect. My Olympus BH2-MA have an aperture diaphragm and a field diaphragm. Probably to avoid these problems. Do you plan to release a more advanced vertical illumination system later? Or maybe PUMA is just not really adapted to light reflected microscopy? If I understand well infinity corrected optics are better for that purpose. It is only because of ghost image caused by the half mirror in finite system? Or also because infinity corrected objectives are more adapted for that?
Hi, thanks for the feedback. In my experience, the system as I designed it works very well in epi-mode as long as the epi-stop and light sinks are used - as I hope you can see from the images in the 'Epi-illumination' video. Ensure you only use black PLA for all light paths - any internally reflected or other stray light entering the system light will degrade the image quality. Also, the degree of collimation of the input light may affect the results - the standard 2x23 lens LC system is what I use, in the configuration shown in my videos. Over-converging or under-converging input light might degrade your experience. I have even done epi-illumination with oil immersion (see the silicon chip die images) and this works very well. Another thing I will say is that it is important to prevent back-reflected light - hence the epi-condenser and epi-black bodies. Infinity objectives are not required to get good results with PUMA epi-illumination. I have always used standard 160 objectives to get the results shown in the videos. Regarding epi-dark field. I believe it is possible to do this with PUMA but I have not tried to implement it. It will probably need a dedicated module that should fit in with the standard system. I am currently working on other aspects of the illumination system including high NA transillumination and more work on phase contrast. I also want to start work on the fully motorised XYZ stage for robotic control nanopositioning experiments - but all this is a lot of work and will take a lot of time! I hope you get your epi-system working well enough for your purposes. If any of the tips here helped, let me know.
@@PUMAMicroscope Thank you for the answer. So the problem is probably my illumination system. I use the black body, indeed. I also have the same problem if I remove it and let the light escape. I will double check everything, but it seems that the light coming out of my illumination system is not perfectly parallel. Hence the problem maybe (it seems to bounce inside the objective, if I remove the objective the image is dark as expected). Any tips to calibrate this part? Thank you. Anyway the following features seems very interesting! And a motorized XYZ stage is really a must. I made one (based on a micrometric XY stage) for my olympus so I can take gigapixels panoramas of integrated circuits with a 100x oil objective, for reverse engineering. Some captures took up to 30h! If it were possible with PUMA, I would be able to make several captures in parallel, so yeah, really looking forward to that. It would also make this field of microscopy more accessible. It's currently very niche, probably because of the high investment required for this kind of setup (we talk about 2000-5000€ if you buy it and don't make it). I will try also to do a motorized stage on my side, I have some low-cost ideas (at least for the X/Y part).
@@PUMAMicroscope So this 5mm spacer is missing on my build: czcams.com/video/cAEB10K8PqI/video.html I can't find it anywhere. Do you think it is related to my problem? Edit: found it right after posting the message... It's in Dominus part 1 => Lower_Collector (if anyone else is looking for it).
@@PUMAMicroscope Found the issue... and it was not the spacer. I tried old Optico Paris objectives instead and I don't have the problem anymore (it's not perfect, but the image is OK). The other objectives act as mirrors on the top lens. Probably because it's some cheap objectives from a cheap Paralux microscope. I was able to use the 10x and 40x objectives of the Optico Paris microscope without losing too much contrast. I will have to try to buy new objectives to see if there are any improvements, because those were taken on old second hand microscopes.
Thanks. That's good to know - yes you want objectives with good anti-reflective coating at the back and blackened casings. Re the illuminator - it is not perfect parallelism that is required but the right amount of angle. The PUMA 2x23 LC LED system with and without spacer have different levels of angle (despite my diagrams showing a neat parallel beam). I haven't tried a perfectly parallel beam here. I have developed a good approximation to a parallel beam illuminator which I will be making some videos on later but I haven't tested that with PUMA epi at this stage. If you were using infinity objectives then I suppose a perfectly parallel input beam at the back would make sense but the 160 objectives have a cone of light out the back rather than a parallel beam (regarding light from the focussed image plane) so a similar cone is what you would ideally want to shine down from the back instead of a perfectly parallel beam. For most practical purposes I'm not sure how much difference this will make though.
Thank you for these great videos and keeping your instrument open source. Waiting for my foundation scope, I'm really interested in upgrading it to a more sophisticated one so I can do trans polarisation contrast imaging for my project. What would you say is the spatial resolution of this technique using Puma? Could I ask please what is the smallest size microbe you were able to image usig trans polarised or Köhler configuration?
Thanks for your support - your scope will be posted in a couple of days but there are customs delays for UK goods entering your country so please watch the tracking and be patient. As for resolution - it depends on the objective and the illuminator. The numerical aperture of the current PUMA trans-polariser is not that great so you should be OK for pond-life microbes but you may have difficulty seeing the tiniest germs (I suggest dark ground microscopy would be better for that than trans-polarising). For normal Köhler resolution will be better and you should be able to see bacteria including TB, cocci, rods, etc. when suitably stained. I am working on even higher NA illuminators which could improve that but that is a development thing - PUMA is a live and active project so you can expect more upgrades and new modules in the months / years ahead. The next video will be on epi-illumination - out in a week or two - so stay tuned for that (and the epi-illuminator should give you the highest resolution of all, limited by the NA of your objective, so you may want to consider that for studying microbes).
@@PUMAMicroscope amazing stuff. Thank you for your reply. I look forward yo your new content. I'm a beginner at microscopy so a lot of stuff you say is new to me. Hopefully I can follow the texts you suggested earlier and try to keep up :)))
Hi, I have another question. I'm trying to make a second light reflected PUMA to use a spare high quality infinity Olympus objective I have. Why in the BoM the "Lens infinity tube" focal length is 100mm? My objectives have "f = 180" written on. Do I need a tube lens with f = 180mm instead? It's an achromat doublet I suppose? Regards
Hello. For any infinity objective (regardless of its make or other features) when the specimen is at the correct working distance from it, the imaging rays coming out the back will all be parallel rays (the imaging BEAM will be diverging - but never mind about that for now, it does not affect the answer to your question). To get those parallel rays to converge to a focus so you can see the image in focus you need to get them to converge at the focal plane of your eyepiece. In the PUMA microscope there is only 100 mm from the position of the (optional) tube lens to the focal plane of the eyepiece, therefore the tube lens must cause those parallel rays to come to a focus 100 mm away from it and so, by definition, it must have a focal length of 100 mm. Most professional infinity microscopes have tube lenses of f=200 mm or thereabouts. This is why using the PUMA with its 'standard' infinity tube lens of f=100 is a compromise and does not give good image correction (the objectives are designed for a tube lens with much longer f). However, you could use a tube lens with f=200 (or just over 200, something like 220 mm) and then you would need to increase the distance to the eyepiece by the appropriate amount - so if you use a tube lens with f=200 mm , just make the ocular tube longer by 100 mm (although things could get a little 'wobbly' if you stick a camera on the end of such a long tube without appropriate support). I hope that all makes sense.
@@PUMAMicroscope Oh I see! Thank you very much for the explanation. Do you think it may be worth the effort to use mirrors to make the system more compact? Or it may just reduce image quality for little gain?
@@oni2ink That mirror thing was the question I had to ask myself when designing the canonical PUMA. I decided against it because it would mean using first surface mirror or a TIR prism and would increase the cost and also mean singificantly more 3D printing and construction. However, for any individual, like yourself, if you are building a system for your own use then the decision is up to you. It shouldn't reduce image quality significantly if you use one first surface mirror but it will add weight and the system will have increased bulk which, if not designed carefully, cause increased vibrations thereby cancelling out the desired benefit. It may be easier to just design a more stable straight monocular tube (thicker walls with buttressing, etc.). Over to you to experiment and see what works.
@@PUMAMicroscope I see, thanks for the clarification. I'll try to increase the tube length, and the thicker walls are a neat solution. My Olympus BH2 have a magnification changer just above the tube lens. If I want something like this on the infinity PUMA version, do you think I can add an optional achromat lens on the tube? For example by using something like your filter slot system?
@@oni2ink For that you will could use a beam expander between the objective and the tube lens. This might reduce image quality - I would avoid it and use a higher res camera instead.
That's pretty interesting, and very well explained. Is this kind of beam splitter usable with infinity corrected optics too? Or do we need a cube splitter for this case? For example, I have an Olympus BH2, and I want to add reflected light illumination on it. What should I choose? Thank you.
Thanks. I am glad you asked this question - it is important. I aim to do a dedicated video on infinity objective use but for now note that, with PUMA use of the optional infinity tube lens in this filter block is more of a concession than a recommendation. It allows infinity objectives to be used but with some important limitations. First, the tube lens has too short a focal length to correct for spherical aberrations and flat field in infinity objectives so, although they will 'work' you will get a very UN-plan field even with expensive professional infinity objectives. Second, the positioning of the tube lens will throw the AR projector out of focus so the HUD will not be useable with infinity objectives with this filter block. The epi-illumination mode should work just fine but not the trinocular camera port (because there is no tube lens for that port). So, while infinity objectives can be used with PUMA these significant limitations mean that I am currently looking at developing a more dedicated 'infinity optics filter block' to join the extant 'simple' and 'advanced' models. Regarding BH2, they are all finite 160 mm tube scopes (not infinity) and their objectives are likewise 160 mm (as shown in the SPlan example in the video) so they will work just fine with the advanced filter block with its plate splitter (and without the infinity tube lens). I have a dedicated BH2 metallurgical microscope in my collection which has a dedicated epi-illumination port. Olympus tend to use cube prism splitters because for them, cost, weight and portability are not concerns so they adopt all the corrective optics discussed in the video. They therefore should give a better quality image - but at a price. I will be doing a dedicated video on epi-illumination and so I hope to demonstrate a comparison between PUMA's epi-illumination system vs. the Olympus BH2 metallurgical - so stay tuned for that.
@@PUMAMicroscope Thank you very much for the detailed answer. I have a BH2-MJL, and all of my objectives are ∞/0. I didn't know that the BH2 models also came with a finite 160 mm tube scope, but now that you mention it I went to see the manuals and it is indeed the case. Good to know. I already have a BH2-MA Brightfield Vertical Illuminator, but this stuff is rare and expensive so I was thinking of making a 3d pritable replacement just in case. So, basically, if I want to make a PUMA only for integrated circuits observation (so light reflected), what do you think is the best? Already, I guess I have to buy new objectives, as my BH2 ones will not be optimal for this, as you explained. Can't wait for the next videos! Regards. Edit: After some research, I found pictures of the interior of the BH2-MA-2 on microbehunter. It's an half mirror. The picture can be found easily on google image with the following keywords: olympus bh2-ma half mirror microbehunter
OK. Sorry - you are of course right - my mistake, I was thinking of the transillumination BH2s. My BH2 metallurgical also has infinity objectives. My points about use of infinity with PUMA remain valid. However, please take note of the stage size limitations of PUMA - most PCBs would not fit on the PUMA stage and even for those small PCBs that do fit, you would not get much working distance to do things like solder tiny SMD parts or some such. For that reason I do not recommend PUMA for PCB work (although it is good for imaging integrated circuit dies - as I will show in the forthcoming epi-illumination video).
Thanks. Sure, here are some freely available resources for further reading: 1. "Optical Microscopy" by Davidson and Abramowitz This detailed reference and tutorial article contains further references for you to go deeper as required and the full article PDF is available free online from Zeiss campus here: zeiss-campus.magnet.fsu.edu/referencelibrary/pdfs/Davidson_Abramowitz_Optical_Microscopy.pdf 2. For lighter reading try this article in the November 2015 issue of MicScape Magazine: www.microscopy-uk.org.uk/mag/artnov15/The%20Mechanical%20Tube%20Length%20Version%201.pdf 3. Here is an online resource: micro.magnet.fsu.edu/primer/anatomy/tubelength.html
Hi again (previous comment got automatically deleted and I'm not sure why). Do you think I can adapt the advanced filter block for a 30mm half mirror? If I increase the height of the filter block, I assume I also need to reduce the tube length? Thank you!
Hello. You have some flexibility in the advanced filter block because there is the space on top for the optional infinity tube lens. I recommend people not to use the tube lens (which is only for infinity corrected objectives) because the f=100 mm focal length of it is too short for high quality use of infinity objectives - I only designed that space there for the tube lens as a concession in case people really needed to use infinity optics. So possibly by extending the semi-mirror slot upwards more than downwards it might fit and all you will sacrifice is the space for the tube lens which you don't need anyway. In that case there will be no need to change the height of anything. I haven't actually tried this so can't be sure it will work but I'm guessing this might be do-able.
@@PUMAMicroscope Indeed good idea, I will see if it fit. Do you have any tips for freecad when editing a design? Removing the chamfer groups one by one is very anoying because it move the content on the top of the hierarchy, so you need to move again everything each time. It's really frustrating, but maybe I'm doing it wrong? I almost feel like it would be faster for me to edit the STL in blender... And thank you for the answer, and great design by the way! It's is really fun to print, even if some little things here and here can probably been improved. But many things are really clever.
See my 'Customising PUMA Part 1' video for my general FreeCAD design / usage approach. When it comes to something like all those chamfers I don't see any way round it - you just have to hit 'delete' and let them all go then re-apply afterwards. However what I do is keep a copy of the intact model in a separate file so when it comes to re-applying the chamfers I just refer to the intact model to tell me what needs (re)chamfering and by how much (so I don't have to remember them all or write them down). Yes, that part is a pain - sorry.
@@PUMAMicroscope Yes I started using FreeCad watching your video. I'm just surprised that it's such a hassle for such simple things, but it seems to be a known issue with the software. Maybe it will be addressed in the future, but at least it works on Linux... When I finish my microscope, would you be interested in feedback? If so, where would you prefer I post it? Thank you.
Sure - feedback is very important. I don't have a central PUMA forum or anything (perhaps I should make one - just very busy these days). I would suggest you post about it on any social media accounts you have like twitter, insta/face or linked in - and your own YT channel. You could also post about it on Reddit - r/3Dprinting, r/functionalprint and even r/microscopy (although one of the mods there banned me for life - not sure why - most of the r/microscopy community actually like the microscope judging by the comments and upvotes my posts got).
Sure - but I don't keep a repository of STL files (they are way too big, the way I make them). So, instead you can just save whatever model you like as an STL using FreeCAD. The 3D printing guide PDF will show you how to do this, step-by-step. Here is the link: github.com/TadPath/PUMA/tree/main/3D_Printing. The black body light sink models are in the 'Dominus_part2.FCStd' FreeCAD file (in the 'Epi-Illumination' group of models in that file) here: github.com/TadPath/PUMA/tree/main/FreeCAD
Wow I’m learning a ton of stuff from your videos concerning optics even though I have zero interest in microscopes. Thanks so much for doing these presentations; they are immensely insightful and well presented.
Thanks. I am planning on doing more videos on diffraction theory, Fourier optics and image processing using the PUMA system as a practical illustration tool with some C programming sessions. So keep an eye on the channel if you are into any of that. A new video will be out this Friday.
This is a great resource for any DIY microscope-optics related projects! Thanks for all the thought and effort put into both the PUMA project and this video.
Thanks. Please tell others about PUMA too. The next video will be on 'Ocular Heads' and should be out by the end of the month.
I come back to say I finally assembled the filter block (with a 20mm half mirror because it was really too hard to adapt for a 30mm one) and it works pretty well with a 5x objective.
I don't have a base yet, and I plan to create a totally different design (only for light reflected), so my tests were a little shaky, but the image quality is very good with the 5x objective. Comparable to my metallographic olympus microscope, but very cheap to make, so really well done.
This will open up a lot of possibilities. I plan also to make an infrared version because I have a microscope camera with a removable IR cut off filter.
I also tried with higher magnification objectives but sadly, the quality deteriorates a lot with very little contrast and a hazy appearance.
It may be caused because it's biological objectives (so they requires a coverglass) but I assume it is also because the LED housing don't have any aperture?
Any ideas to improve the quality? Did i miss something?
Also, do you think it is possible to use dark field with reflected light on PUMA? Or the objectives are the main limitation? (my olympus microscope requires special neo objectives for that purpose + a different vertical illuminator).
Thank you!
Edit:
After some investigation, it's indeed caused by the light reflected from the objective, so even if there is no sample to observe I have a bright image (and therefore a big loss of contrast). If I add a small aperture after the led illumination system it seems to reduces a lot the problem, but it's not perfect.
My Olympus BH2-MA have an aperture diaphragm and a field diaphragm. Probably to avoid these problems.
Do you plan to release a more advanced vertical illumination system later? Or maybe PUMA is just not really adapted to light reflected microscopy? If I understand well infinity corrected optics are better for that purpose. It is only because of ghost image caused by the half mirror in finite system? Or also because infinity corrected objectives are more adapted for that?
Hi, thanks for the feedback. In my experience, the system as I designed it works very well in epi-mode as long as the epi-stop and light sinks are used - as I hope you can see from the images in the 'Epi-illumination' video. Ensure you only use black PLA for all light paths - any internally reflected or other stray light entering the system light will degrade the image quality. Also, the degree of collimation of the input light may affect the results - the standard 2x23 lens LC system is what I use, in the configuration shown in my videos. Over-converging or under-converging input light might degrade your experience. I have even done epi-illumination with oil immersion (see the silicon chip die images) and this works very well. Another thing I will say is that it is important to prevent back-reflected light - hence the epi-condenser and epi-black bodies. Infinity objectives are not required to get good results with PUMA epi-illumination. I have always used standard 160 objectives to get the results shown in the videos.
Regarding epi-dark field. I believe it is possible to do this with PUMA but I have not tried to implement it. It will probably need a dedicated module that should fit in with the standard system. I am currently working on other aspects of the illumination system including high NA transillumination and more work on phase contrast. I also want to start work on the fully motorised XYZ stage for robotic control nanopositioning experiments - but all this is a lot of work and will take a lot of time! I hope you get your epi-system working well enough for your purposes. If any of the tips here helped, let me know.
@@PUMAMicroscope Thank you for the answer. So the problem is probably my illumination system. I use the black body, indeed. I also have the same problem if I remove it and let the light escape.
I will double check everything, but it seems that the light coming out of my illumination system is not perfectly parallel. Hence the problem maybe (it seems to bounce inside the objective, if I remove the objective the image is dark as expected). Any tips to calibrate this part?
Thank you.
Anyway the following features seems very interesting! And a motorized XYZ stage is really a must. I made one (based on a micrometric XY stage) for my olympus so I can take gigapixels panoramas of integrated circuits with a 100x oil objective, for reverse engineering. Some captures took up to 30h!
If it were possible with PUMA, I would be able to make several captures in parallel, so yeah, really looking forward to that. It would also make this field of microscopy more accessible. It's currently very niche, probably because of the high investment required for this kind of setup (we talk about 2000-5000€ if you buy it and don't make it).
I will try also to do a motorized stage on my side, I have some low-cost ideas (at least for the X/Y part).
@@PUMAMicroscope So this 5mm spacer is missing on my build: czcams.com/video/cAEB10K8PqI/video.html
I can't find it anywhere. Do you think it is related to my problem?
Edit: found it right after posting the message... It's in Dominus part 1 => Lower_Collector (if anyone else is looking for it).
@@PUMAMicroscope Found the issue... and it was not the spacer.
I tried old Optico Paris objectives instead and I don't have the problem anymore (it's not perfect, but the image is OK). The other objectives act as mirrors on the top lens. Probably because it's some cheap objectives from a cheap Paralux microscope.
I was able to use the 10x and 40x objectives of the Optico Paris microscope without losing too much contrast.
I will have to try to buy new objectives to see if there are any improvements, because those were taken on old second hand microscopes.
Thanks. That's good to know - yes you want objectives with good anti-reflective coating at the back and blackened casings. Re the illuminator - it is not perfect parallelism that is required but the right amount of angle. The PUMA 2x23 LC LED system with and without spacer have different levels of angle (despite my diagrams showing a neat parallel beam). I haven't tried a perfectly parallel beam here. I have developed a good approximation to a parallel beam illuminator which I will be making some videos on later but I haven't tested that with PUMA epi at this stage. If you were using infinity objectives then I suppose a perfectly parallel input beam at the back would make sense but the 160 objectives have a cone of light out the back rather than a parallel beam (regarding light from the focussed image plane) so a similar cone is what you would ideally want to shine down from the back instead of a perfectly parallel beam. For most practical purposes I'm not sure how much difference this will make though.
Hey CZcams algorithm, please cut back a little on cat video and promote more high quality science video like that!
Thank you for these great videos and keeping your instrument open source. Waiting for my foundation scope, I'm really interested in upgrading it to a more sophisticated one so I can do trans polarisation contrast imaging for my project. What would you say is the spatial resolution of this technique using Puma? Could I ask please what is the smallest size microbe you were able to image usig trans polarised or Köhler configuration?
Thanks for your support - your scope will be posted in a couple of days but there are customs delays for UK goods entering your country so please watch the tracking and be patient. As for resolution - it depends on the objective and the illuminator. The numerical aperture of the current PUMA trans-polariser is not that great so you should be OK for pond-life microbes but you may have difficulty seeing the tiniest germs (I suggest dark ground microscopy would be better for that than trans-polarising). For normal Köhler resolution will be better and you should be able to see bacteria including TB, cocci, rods, etc. when suitably stained. I am working on even higher NA illuminators which could improve that but that is a development thing - PUMA is a live and active project so you can expect more upgrades and new modules in the months / years ahead. The next video will be on epi-illumination - out in a week or two - so stay tuned for that (and the epi-illuminator should give you the highest resolution of all, limited by the NA of your objective, so you may want to consider that for studying microbes).
@@PUMAMicroscope amazing stuff. Thank you for your reply. I look forward yo your new content. I'm a beginner at microscopy so a lot of stuff you say is new to me. Hopefully I can follow the texts you suggested earlier and try to keep up :)))
Hi, I have another question.
I'm trying to make a second light reflected PUMA to use a spare high quality infinity Olympus objective I have.
Why in the BoM the "Lens infinity tube" focal length is 100mm?
My objectives have "f = 180" written on. Do I need a tube lens with f = 180mm instead?
It's an achromat doublet I suppose?
Regards
Hello. For any infinity objective (regardless of its make or other features) when the specimen is at the correct working distance from it, the imaging rays coming out the back will all be parallel rays (the imaging BEAM will be diverging - but never mind about that for now, it does not affect the answer to your question). To get those parallel rays to converge to a focus so you can see the image in focus you need to get them to converge at the focal plane of your eyepiece. In the PUMA microscope there is only 100 mm from the position of the (optional) tube lens to the focal plane of the eyepiece, therefore the tube lens must cause those parallel rays to come to a focus 100 mm away from it and so, by definition, it must have a focal length of 100 mm.
Most professional infinity microscopes have tube lenses of f=200 mm or thereabouts. This is why using the PUMA with its 'standard' infinity tube lens of f=100 is a compromise and does not give good image correction (the objectives are designed for a tube lens with much longer f). However, you could use a tube lens with f=200 (or just over 200, something like 220 mm) and then you would need to increase the distance to the eyepiece by the appropriate amount - so if you use a tube lens with f=200 mm , just make the ocular tube longer by 100 mm (although things could get a little 'wobbly' if you stick a camera on the end of such a long tube without appropriate support).
I hope that all makes sense.
@@PUMAMicroscope Oh I see! Thank you very much for the explanation.
Do you think it may be worth the effort to use mirrors to make the system more compact? Or it may just reduce image quality for little gain?
@@oni2ink That mirror thing was the question I had to ask myself when designing the canonical PUMA. I decided against it because it would mean using first surface mirror or a TIR prism and would increase the cost and also mean singificantly more 3D printing and construction. However, for any individual, like yourself, if you are building a system for your own use then the decision is up to you. It shouldn't reduce image quality significantly if you use one first surface mirror but it will add weight and the system will have increased bulk which, if not designed carefully, cause increased vibrations thereby cancelling out the desired benefit. It may be easier to just design a more stable straight monocular tube (thicker walls with buttressing, etc.). Over to you to experiment and see what works.
@@PUMAMicroscope I see, thanks for the clarification. I'll try to increase the tube length, and the thicker walls are a neat solution.
My Olympus BH2 have a magnification changer just above the tube lens.
If I want something like this on the infinity PUMA version, do you think I can add an optional achromat lens on the tube? For example by using something like your filter slot system?
@@oni2ink For that you will could use a beam expander between the objective and the tube lens. This might reduce image quality - I would avoid it and use a higher res camera instead.
That's pretty interesting, and very well explained.
Is this kind of beam splitter usable with infinity corrected optics too? Or do we need a cube splitter for this case?
For example, I have an Olympus BH2, and I want to add reflected light illumination on it. What should I choose?
Thank you.
Thanks. I am glad you asked this question - it is important. I aim to do a dedicated video on infinity objective use but for now note that, with PUMA use of the optional infinity tube lens in this filter block is more of a concession than a recommendation. It allows infinity objectives to be used but with some important limitations. First, the tube lens has too short a focal length to correct for spherical aberrations and flat field in infinity objectives so, although they will 'work' you will get a very UN-plan field even with expensive professional infinity objectives. Second, the positioning of the tube lens will throw the AR projector out of focus so the HUD will not be useable with infinity objectives with this filter block. The epi-illumination mode should work just fine but not the trinocular camera port (because there is no tube lens for that port). So, while infinity objectives can be used with PUMA these significant limitations mean that I am currently looking at developing a more dedicated 'infinity optics filter block' to join the extant 'simple' and 'advanced' models.
Regarding BH2, they are all finite 160 mm tube scopes (not infinity) and their objectives are likewise 160 mm (as shown in the SPlan example in the video) so they will work just fine with the advanced filter block with its plate splitter (and without the infinity tube lens). I have a dedicated BH2 metallurgical microscope in my collection which has a dedicated epi-illumination port. Olympus tend to use cube prism splitters because for them, cost, weight and portability are not concerns so they adopt all the corrective optics discussed in the video. They therefore should give a better quality image - but at a price. I will be doing a dedicated video on epi-illumination and so I hope to demonstrate a comparison between PUMA's epi-illumination system vs. the Olympus BH2 metallurgical - so stay tuned for that.
@@PUMAMicroscope Thank you very much for the detailed answer.
I have a BH2-MJL, and all of my objectives are ∞/0. I didn't know that the BH2 models also came with a finite 160 mm tube scope, but now that you mention it I went to see the manuals and it is indeed the case. Good to know.
I already have a BH2-MA Brightfield Vertical Illuminator, but this stuff is rare and expensive so I was thinking of making a 3d pritable replacement just in case.
So, basically, if I want to make a PUMA only for integrated circuits observation (so light reflected), what do you think is the best?
Already, I guess I have to buy new objectives, as my BH2 ones will not be optimal for this, as you explained.
Can't wait for the next videos!
Regards.
Edit: After some research, I found pictures of the interior of the BH2-MA-2 on microbehunter. It's an half mirror.
The picture can be found easily on google image with the following keywords: olympus bh2-ma half mirror microbehunter
OK. Sorry - you are of course right - my mistake, I was thinking of the transillumination BH2s. My BH2 metallurgical also has infinity objectives. My points about use of infinity with PUMA remain valid. However, please take note of the stage size limitations of PUMA - most PCBs would not fit on the PUMA stage and even for those small PCBs that do fit, you would not get much working distance to do things like solder tiny SMD parts or some such. For that reason I do not recommend PUMA for PCB work (although it is good for imaging integrated circuit dies - as I will show in the forthcoming epi-illumination video).
@@PUMAMicroscope Yeah, I was thinking about observing integrated circuit dies. I will wait for the epi-illumination video!
Thank you.
Super! Can you suggest a classic text (obtainable) that covers the mechanical details in the first part? Thanks
Thanks. Sure, here are some freely available resources for further reading:
1. "Optical Microscopy" by Davidson and Abramowitz
This detailed reference and tutorial article contains further references for you to go deeper as required and the full article PDF is available free online from Zeiss campus here:
zeiss-campus.magnet.fsu.edu/referencelibrary/pdfs/Davidson_Abramowitz_Optical_Microscopy.pdf
2. For lighter reading try this article in the November 2015 issue of MicScape Magazine:
www.microscopy-uk.org.uk/mag/artnov15/The%20Mechanical%20Tube%20Length%20Version%201.pdf
3. Here is an online resource:
micro.magnet.fsu.edu/primer/anatomy/tubelength.html
@@PUMAMicroscope Great, thanks. Kit arrived!
Thanks for letting me know.
Hi again (previous comment got automatically deleted and I'm not sure why).
Do you think I can adapt the advanced filter block for a 30mm half mirror?
If I increase the height of the filter block, I assume I also need to reduce the tube length?
Thank you!
Hello. You have some flexibility in the advanced filter block because there is the space on top for the optional infinity tube lens. I recommend people not to use the tube lens (which is only for infinity corrected objectives) because the f=100 mm focal length of it is too short for high quality use of infinity objectives - I only designed that space there for the tube lens as a concession in case people really needed to use infinity optics. So possibly by extending the semi-mirror slot upwards more than downwards it might fit and all you will sacrifice is the space for the tube lens which you don't need anyway. In that case there will be no need to change the height of anything. I haven't actually tried this so can't be sure it will work but I'm guessing this might be do-able.
@@PUMAMicroscope Indeed good idea, I will see if it fit.
Do you have any tips for freecad when editing a design? Removing the chamfer groups one by one is very anoying because it move the content on the top of the hierarchy, so you need to move again everything each time. It's really frustrating, but maybe I'm doing it wrong?
I almost feel like it would be faster for me to edit the STL in blender...
And thank you for the answer, and great design by the way! It's is really fun to print, even if some little things here and here can probably been improved.
But many things are really clever.
See my 'Customising PUMA Part 1' video for my general FreeCAD design / usage approach. When it comes to something like all those chamfers I don't see any way round it - you just have to hit 'delete' and let them all go then re-apply afterwards. However what I do is keep a copy of the intact model in a separate file so when it comes to re-applying the chamfers I just refer to the intact model to tell me what needs (re)chamfering and by how much (so I don't have to remember them all or write them down). Yes, that part is a pain - sorry.
@@PUMAMicroscope Yes I started using FreeCad watching your video.
I'm just surprised that it's such a hassle for such simple things, but it seems to be a known issue with the software.
Maybe it will be addressed in the future, but at least it works on Linux...
When I finish my microscope, would you be interested in feedback?
If so, where would you prefer I post it?
Thank you.
Sure - feedback is very important. I don't have a central PUMA forum or anything (perhaps I should make one - just very busy these days). I would suggest you post about it on any social media accounts you have like twitter, insta/face or linked in - and your own YT channel. You could also post about it on Reddit - r/3Dprinting, r/functionalprint and even r/microscopy (although one of the mods there banned me for life - not sure why - most of the r/microscopy community actually like the microscope judging by the comments and upvotes my posts got).
May I have the STL file of the Black body light sinks?
Sure - but I don't keep a repository of STL files (they are way too big, the way I make them). So, instead you can just save whatever model you like as an STL using FreeCAD. The 3D printing guide PDF will show you how to do this, step-by-step. Here is the link: github.com/TadPath/PUMA/tree/main/3D_Printing. The black body light sink models are in the 'Dominus_part2.FCStd' FreeCAD file (in the 'Epi-Illumination' group of models in that file) here: github.com/TadPath/PUMA/tree/main/FreeCAD
Great!@@PUMAMicroscope