The PWG, Young's Slits and Köhler's Conjugates
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- Опубликовано: 23 июл 2024
- Here I describe the Plane Wavefront Generator (PWG) - a module that produces spatially coherent EM radiation from a normal LED! I also present Young's slits experiment using it with a 3D printed slits mask. Finally I show how this relates to Köhler illumination by filling in some theory on the microscope conjugate planes.
CONTENTS
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00:00 Intro to the Plane Wavefront Generator (PWG)
01:05 Parallel rays vs. parallel beams
06:32 Building the PWG
13:40 Collimating the PWG
15:14 Young's slits with the PWG and 3D printed 'slits'
17:24 Köhler's conjugates
SUPPORT PUMA
============
PUMA is an open source microscopy project. You can help support the project by:
1. Become a Patron: / pumamicroscope
2. Donate via PayPal: www.paypal.com/donate/?hosted...
3. Simply subscribing to this RUclips channel, like, comment and share these videos.
4. Spread the word - post the news about PUMA and link to this RUclips channel on your social media sites and any other outreach method (tell your friends, colleagues, students or teachers and lecturers about PUMA, for example).
5. Consider purchasing your optics and related supplies from our affiliated online optics store, OptArc.co.uk ( www.optarc.co.uk/ )
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PARTS AND TOOLS
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For the latest details and instructions on how to print the parts see the 'PUMA_3D_Printing_Guide.pdf' and 'Bill_of_Materials' spreadsheet on the PUMA GitHub page ( github.com/TadPath/PUMA ).
3D Printed Models Introduced in this Video
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Dominus (File: Dominus_part3.FCStd):
PWG parts
Young's slits parts
Non-Printed Parts and Tools
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No changes were introduced with this video.
LINKS TO REFERENCED VIDEOS
==========================
First Köhler video:
• Köhler Illumination - ...
LED and Lower Collector
• The LED Illuminator an...
Trans-Polarisation Illuminator
• The Trans-Polarisation...
Photology 3: Wavefronts
• Photology 3: Represent...
Photology 4: Coherence
• Photology 4: Coherence
OTHER LINKS
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PARD Capture software:
github.com/TadPath/PARDUS/tre...
PUMA Köhler Illuminator Specs document:
github.com/TadPath/PUMA/tree/...
FOR FURTHER INFORMATION
=======================
1. Open access write-up about PUMA on the FreeCAD blog:
blog.freecad.org/2023/02/13/a...
2. The official PUMA GitHub page where you can download the specs and source files to build or customise your own PUMA system:
github.com/TadPath/PUMA
3. The scientific peer reviewed publication on PUMA that was published in 2021 in the Journal of Microscopy (a journal of the Royal Microscopical Society) available here:
pubmed.ncbi.nlm.nih.gov/34151...
onlinelibrary.wiley.com/doi/1...
Thanks for your interest in the PUMA microscope system.
PJT 01/03/23 
Наука
What an immense work.. No words..
This is what we searched for to take a perfect microchip shoots with high quality light.
Thanks. Yes - micro-Z stepping interferometry of chip surfaces is one application. I would like to try that and make a video on the results - but of course I'll be very happy if others beat me to it!
Its's a shame videos like this don't get more attention. So much work has gone into the microscope as well as this video. Keep educating you are doing a great job!!
Thanks for the encouraging comments. Sometimes I do wonder - I mean 'big' RUclipsrs can just post a video of them sneezing in front of the camera and get 10K views in the first hour - it took my first PUMA video almost 2 years to hit 10K and most of my other videos never reach 1K. But I still have some knowledge to teach - which I think at least some people will find valuable - so I will carry on for now.
@PUMAMicroscope Big RUclipsrs videos have high entertaining value.
Yours have tremendous value but for niche audience. And i'm grateful they do exist.
@@PUMAMicroscope We might be a small crowd, but we're a crowd of enthusiasts, professionals and scholars all over the world that are highly interested in the topic.
@@PUMAMicroscope It's a bottle in the sea waiting to be found.
On youtube the quality is not what get more likes, it's what the algorithm promotes.
I experienced this myself with a simulation I made, requiring a lot of work. Then I published the video and I got a few likes...
Months later, for whatever reason, the algorithm decided to highlight the video. It got 240k views and thousands of likes in just a few days...
But in the end, it didn't bring me anything at all, because youtube is youtube. It's mostly for entertainment.
Your channel may be small, but people here are very interested.
Myself I watched more than 10x some videos just to understand some concepts.
Optics is really hard to grasp without visual / real world applications. And you did a great job with that. You really are the best / most comprehensible reference on the subject, IMO.
@@oni2ink Thanks.
Very interesting. Thanks for the video.
I was curious about using an objective in this kind of setup. Happy to see it's possible!
We can use this to measure precisely the back focal plane of any objective right?
Maybe it can be used in white light interferometry too? But without the last lens?
Is this PWG useful in microscopy in general? Do you have plans for uses in the future with PUMA microscope?
Thanks. Yes you can use PWG to measure BFP - although simply pointing the objective at a distant scene will also work. I will be using the PWG to demonstrate Abbe's diffraction theory of image formation in the light microscope and some Fourier optics work (at least that's the plan). As for white light interferometry and OCT - I would like to make my precision PUMA XYZ stage a reality first but, if successful, those are some of the applications that the PWG can be used for in conjunction with the beam splitter of the advanced filter block (although it might also work with the Z-motorised current stage with precise microstepping in Z - I need to experiment). So there's a tonne of PUMA material still to come.
@@PUMAMicroscope This looks very promising. I'm very hyped!
I hope you'll find some good solutions for the motorized stage, but it's really not a trivial solution.
Atm my best result was using an aluminum frame made of 2020 extrusions to mount the microscope on a linear rail using a lead screw for the Z axis, and two double linear rails (motorized) for X and Y. It's surprisingly very precise and works even with a 100x objective.
But, well, it's probably larger than what you ever want (something about 24x24x40cm - 40 cm height mainly because I have a 80mm tube extension).
But on the other hand, it's very lightweight (the frame contains more emptiness than anything...) so I have a lot of vibration issues.
I'm not sure if motorized and "portable" are really in the realm of the possible.
But linear rails are pretty good at this task, and even if the precision is not perfect, if you are doing backlash compensation you can get great results and easier stitching later.
Next I want to try to 3d print linear rails to see if we can get good results... or not (in order to cut prices)!
@@PUMAMicroscope Also, it may interest you - I recently got a monochrome global shutter raspberry pi camera based on the OV9281 sensor. It's only 35€, and the quality is really good - I think it may be a great deal to use for microscopy in specific applications, because monochrome camera are generally VERY expensive, especially with a global shutter...
If you want to get one just search for Innomaker OV9281 camera.
@@PUMAMicroscope Also, it may interest you - I recently got a monochrome global shutter pi camera based on the OV9281 sensor.
I think it may be great to use for microscopy in specific applications, because monochrome camera are generally VERY expensive, especially with a global shutter...
Search for Innomaker OV9281 camera.
You also have USB ones with very low framerate on ali. But probably good enough for experimentation.
Also, it may interest you - I recently got a high framerate monochrome global shutter pi camera based on the OV9281 sensor for very cheap.
Only "downside", it's only 1280 x 800.
But I'm sure it's enough for a lot of applications. I plan to use one to make a spectrometer, and another one for microscopy in general.