The explanation of the microscope experiment contains a misleading simplification for the sake of understandability. Can you find which simplification that is?
Great video and amazing explanation. You have addressed a very important aspect of the angular resolution of the Webb and clarified that Hubble gives actually sharper images than Webb which previously was not understood and they gave the wrong impression that Webb is sharper than the Hubble. However Webb can collect more light and therefore will have a longer range. Nevertheless, you did not address that infrared spectrum of Webb is not absorbed so much as visible spectrum of Hubble from space dust, gasses and nebulas. Therefore with the Webb we will seethrough these obstacles which is a very important feature of infrared telescopy.
About the spacing between the mirror segments of the Webb and the diffraction and sharpness problems this can cause? I believe the black substrate material behind the mirrors will absorb all these artifacts.
the way you showed us the wave propagating on screen doesn't make a lot of sense to me. Im not entirely sure how you did that to be honest, was it by changing the focal length?
Explaining that the light pattern outside the aperture looks like a wave because that's the only way light can travel is misleading -- shining a laser across a flat surface wouldn't look wavy, even though it's also traveling as an electromagnetic wave. The wave pattern is an interference effect with the wavelets traveling at the edge of the aperture
@@SodiumNitrateBot Yes, Lucas, spot on. I am suggesting in that part that what you are seeing is the actual EM-wave moving out and inwards, which is of course not true. You are still just seeing diffraction. However, because you can only see diffraction to the point that the field extends, there will still be some relationship between the extend of the energy redistribution and the extend of the diffraction pattern. I left this in to let people discover this themselves. @Alex Domatas the patterns are recorded by changing the focal position of a microscope with a very shallow depth of focus. In this way you can observe what happens at a specific "slice" of space. I used this same method in previous videos such as the one on Photon sieves.
I’m not aware of any other UA-cam channel that has your combination of approachability for an optics beginner like me, combined with depth of technical detail if I make the effort to study it. Thanks so much, and please keep the videos coming.
Most schools of engineering are like that, these days. Simply focused on cramming as much information into a students head as possible without regard for actually understanding it.
Living in Tucson Arizona and surrounded by a large astronomical and optical research community I have had the opportunity to talk with many optical researchers and astronomers. You sir have an exceptional ability to communicate the science of optics. I appreciate your efforts and hope you continue as I have learned a great deal from your videos. cheers
Im a hobbyist in tucson. What approachable communitys do you all speak off? I got an 8" dobsonian and some great books, but i need more stellar friends!:)
Your videos are always great! Yes, I'd be interested to know about segmented mirror telescopes. It does seem like diffraction would be a problem. Maybe they use similar tricks as semiconductor masks?
Thanks Ben. Yes, as long as the diffractive edges are regularly spaced, they represent a very specific frequency component in the Fourier transform. I'm not aware of how exactly they do it, you could imagine that it is some kind of low-frequency spatial filtering. That might also explain why the outer perimeter of the mirror has an hexagonal shape and has not been rounded. Because only then it the same filter can be used for both segment spacings as well as the edge.
@@LarsBerntzon In chip masks it works differently. The precise mask pattern is actually irrelevant, it's only about the light distribution at the photoresist layer. So you use computational methods to optimize this intensity profile by using specific diffraction effects and write the patterns to achieve this onto the litho mask.
@@HuygensOptics Ah, I see. So if we could go to the end of the universe and place a really big specially crafted mask there we could get really good images in our telescopes :)
I got a master's degree specializing in electromagnetic wave propagation and your explanation of the physical cause of edge diffraction is the best ever! It really brings together the mathematics and real world observations. And yes, what you show as "waves" in the microscope image are actually interference patterns, not the actual light waves. This is a good way to visualize what is going on with the energy transfer.
I had most of this material at the university in a course on industrial imaging, at the time it was quite fascinating and i am surprised how much i put it to use working. It is so much fun to watch these videos and gain more info and insights on these topics. The quality of content you make and put out there for free is really astonishing. I cant thank you enough!
I would have loved to have this person as my teacher at the University. It does not matter how hard or complex the topic is, he always finds the way to make it extremely attractive to me... and I am just totally ignorant when it comes to physics or optics. Chapeau!
@@Emenblade I can imagine that when they were deciding the budget for JWST somebody told them "ok, we can give you enough money to make a telescope as good as hubble but in infrared, you are saying that it is a hubble replacement anyway, just in infrared, alright? We won't fund anything bigger than that".
@@TheoEvian Because the first object from JWT to be posted on Reddit will be compared side by side to the image from Hubble, and every crackpot will claim JWT is a waste of money as it produces worse images. So I guess NASA cares about Reddit Karma?
@@Tore_Lund They do care about PR quite a lot but I don't think that would be the main reason. As I said, I can imagine the image quality being a part of the budget negotiations.
Just gotta say, I love this channel much. Plenty of other channels offer shallow takes on similar topics, but this is the only channel I know that really dives deep into the subject of optics, and presents in a manner that most people with an interest in science can learn from. Thanks so much for taking the time to make these videos.
After several weeks of James Webb news, I needed a fresh dose of Huygens Optics. Your videos are so well made that an interested novice, like myself, can follow along.
Ooooopssss there goes resolution in the deeper infrared. That was a remarkable clear and visually superb illustrated explanation, understandable for a layman like me. LOVED IT 💯!
Indeed. Not an oops though, it Is highly specialized and likely hundreds of hours were poured into deciding exactly where to focus our instrumentation. You can not have it all, and in this case they preferred to Have great balance between visible and infrared. Rather than deep infrared only without any visible light
Great explanation of these concepts. If you read any of the blogs on photography or cameras, you will be amazed at the confusion amongst photographers on the topic of "resolution" of lenses.
A remarkable presentation filled with teaching and discussion RE:JWST. As long as you identify fundamental limitations to optical performance, JWST will be 'seen' as remarkable with potentially new scientific data for cosmologists. Without belaboring points, a larger mirror could not have been launched today and high red shift demands longer wavelengths. JSWT will (hopefully) collect the only available photons from high red shift objects - full stop. Your video is one of the most well prepared and rigorous I have ever seen; I particularly like the energy discussion. I will review Feymann's lectures again to compare with your presentation.
I've been working in optics for almost a quarter century, and I have to say that this guy has a gift at explaining things. I'm a little envious, actually.
Very nice Video! I am working in the field of optics and I got some amazing new perspectives from your videos. I think another advantage of the longer wave length of the James Webb telescope is that you can observe through dust which is not possible with visible light.
Or you can look at it in terms of a spatial Fourier transform, translating between position and k-space. The spatial profile between the aperture/lens/mirror and the focus can be described by a fractional Fourier transform. This then tells you, that the k-vector distribution created by the round aperture in front of a lens makes a focus which is its Fourier transform, an Airy disk.
@@HuygensOptics Speaking of Fourier, would it make sense to make apertures with Gaussian or raised cosine edges? E.g. via gradient in optical density? Those would result in less ripple. Another question - just like we use equalisation in digital communication, would it be possible to compensate for some of the distortion caused by the finite aperture using digital filters?
You just delivered the single best explanation to why a pinhole lens has an optimal diamater. I always heard, that diffraction causes the image to get less sharp if you have an apperature that is too small, but I never really understood why. Your graphics really helped me too wrap my head around it. Such a great Video!
Thank you for making this video - it's extremely informative. I am working on my PhD in Astrophysics, and you're still educating me. The surface-tension analogy and explanation for the Huygens-Fresnel principle was particularly eye-opening.
It seems like it should be possible to set limits on the possible granularity of spacetime by looking for gaps in the stretched wavelengths. Thank you for the thorough going over on aperture.
Als iemand die halverwege de middelbare school natuurkunde liet vallen, nooit de uni heeft betreden, en later pas astrofotografie heeft opgepakt... moet ik zeggen dat ik de uitleg en combinatie met praktijk beelden super overzichtelijk en begrijpelijk vind. Goed werk!
Jeroen: Thank you for this video. It has let me add your astute observations on diffraction to my own patchwork of understanding. And I appreciate your sharing your extraordinary optical creations through your other videos. You are making an outstanding contribution to the world wide web!
I am fascinated by your clear and detailed explanation of the role of the diffraction limit on resolution. The last time I was dealing with it has been 45 years ago in the advanced internship (Fortgeschrittenen-Praktikum) physics studies. Since then I wondered that endoscopes and miniature cameras of mobile phones were able to supply such good images as never going into details. Now suddenly by following your video I experience more clarity. It is a great pleasure!
The presenter pans across a lot of physics, not just optics. The presentation is so well thought through that a lot of difficult concepts get explained so ordinary mortals can understand. Max kudos! But should we be surprised at the Dutch who currently (Q3/2023) have Robbert Dijkgraaf as Minister of Education. Dhr Dijkgraaf is an internationally known theoretical physicist, former director of the Institute for Advanced Study at Princeton (a role taken by Robert Oppenheimer in the 1950s). So brain the size of a planet, close enough - education in good hands.
This is the only video on youtube that actually explained Diffraction so effectively that I can't even express. Now I know why everyone says don't shoot above f11 with most lenses because smaller the size of aperature the angle at which the incoming light will diffract so severely that most of it won't fall on sensor so less resolution/softer images. Also Thank you sir for that JWST explanation I was commenting everywhere saying the apparent resolution of JWST is basically even lower than hubble But so many people are just waiting for the images. Also IR is the reason why JWST has only 2MP sensors in its cameras to help it get as light as possible & not care about resolution as much as there is literally no way anyways.
NIRCam instrument consists of an array of ten 2048x2048 px sensors, so it's roughly a 40 MP imager. Furthermore the optic correction capabilities of JWST are far better than those of Hubble. Given it can work up to 600 nm (visible orange), it will provide high resolutions images, even if these will not give the most scientifically relevant results.
@@robcavazz Thats what I don't think they would have designed & made such a masterpiece if it e=was not even higher resolution. Guess all have to wait and watch which turns out to be true. But being an engineer myself I have immense amount of faith in the engineers who designed all of jwst the optics[USA guys] & ofc Instruments[Canada guys]. BTW do you know how they will add all the colors like the colors closer to blue in wavelengths? Which techniques? Also is it same for IR & Far visible range or it differs?
When you describe the effect of relaxing boundary conditions, you're correctly describing the physics of diffraction. But I would argue that Huygen's principle denotes something more specific, even though I agree that this isn't always understood when people present it as if it were an exact description of nature. Huygens gave an approximate description of (linear) wave propagation that has one fundamental physical ingredient: the superposition principle. This ability to form superpositions makes it possible (a) to consider every point as the source of a "spherical wave," and (b) to reconstruct the wave at any other point from the spherical-wave contributions that originated at other points. To do this right, you have to do certain integrals (using Green's functions). The construction in Huygens' principle is an approximation to this method that captures the main phenomena reasonably well (in three dimensions, but ironically not so well in two).
First video I have just seen of you and can just hope, you teach other people in some way other than youtube. Man this was spot on explanation and new information without the bla bla around other stuff!
I hate to say it but this video has deflated a bit of my excitement for jwst. Up until now I had the idea in my head of jwst being able to literally zoom further out, and to be able to resolve those more distant objects just as well as Hubble. I have been imagining resolved images tracing the first stars ever born, and then being able to watch step by step as they coalesce into galaxies. This video has made it clear that we won’t be getting those images. I get that there is still an immeasurable amount of new science sure to come from the observatory, I’m just a bit bummed that the super-mega-ultra deep field of my minds eye is likely still one or two generations of space telescopes out…
That is something that has always frustrated me about the science journalism surrounding the James Webb. It has always been sold as a bigger/better Hubble, but it's not. It's an instrument with a totally different purpose. I have been worried for years that the general public might be disappointed when it "fails" to generate "better" results. Nothing against JWST. Just 100% a failure to explain what the goals and capabilities are. Which is a shame.
@@martinmckee5333 Most journalists aren't paid enough to care about anything. Most articles are written on short deadlines by people not qualified to write them, while they are working on several other similar articles besides. Under these circumstances, it's not surprising such incredibly poor coverage is given to every subject.
@@lobsterbark Not surprising, no. But still disappointing. I'm convinced that the quality of science journalism (or lack thereof), is a big reason for the current lack of excitement in and outright distrust of science by the general population.
Eon space labs is doing great. Really impressed with their work in very short time and limited resources. Keep doing good job Team Eon Space Labs (ESL).👏👏👏
It's the same principle as why you don't see the obstruction by the secondary mirror and the arms that hold it, they are not in focus. They form, in the worst case scenario, if the gaps were very big, a slight gradient on the image. (but I'm sure mr Huygens can explain it better). edit: it could be that they cause some weird difraction spikes on very bright stars, not sure about that.
This is not the first video from your channel that I see, but even more than before I'm mesmerized! You deserve millions of subscribers. Thank you very much for this amazing content!
Great great great video! I didn't even know how curious I was about this stuff. Your voice is super relaxing and you're so informative, too. We received a little 80mm aperture hobby telescope for christmas,and are already looking at others after seeing the moons of Jupiter.
I agree with the position of explaining light in the same manner as we would any other form of energy. Very good video my good sir, thanks for making this. As per typical with your content I find my self learning about something that I didn't even consider was a thing to learn.
Good video. I am an amateur photographer. The facts laid out here are the reason, that people claiming "My phone does just as good pictures as your big camera" drive me mad.
As a simple viewer of this fascinating field of science, combined with your capability to communicate these complicated terms in a way simpler mood, is outstanding. With this background on my side, my expectations for the web space telescope were rather *BIG*... but you let me look better at the physical reality. I'm a bit sad, but THANKS!
What a beautiful video!!! I would have loved if you teased the fact that you are going to give such a good explanation at the end, I was really frustrated at the beginning because you said a lot of things that are so and so, and you made no indication that you will explain later. I got instantly so curious that I stopped the video in 1/4 going to look elsewhere for answers. After a quick look at the comments, I came to the conclusion that you actually will explain, and I just need to be patient. :) Also for me, the key was first understanding the intuition, then the formula, that order would feel more natural to me. :) Thank you so much for these videos, I was incredibly curious about diffraction at boundaries for a long time and no physicist I talked with was able to give me an explanation I was happy with. Great insights!
I love your explanations! They are so clear and interesting. I'm very excited to see what the Webb telescope will show us. I have a distinct memory of getting mild vertigo years ago watching a slow zoom in on some part of the deep field image and realizing that all those "stars" were actually galaxies. Thanks for your care in making such good sciences content.
Thank you for this extremely clear explanation. I find that experiments like Webb and Ligo are truly physical science marvels. There was, I believe, and still is an infrared telescope aboard a large aircraft flying at roughly 12 km. The older one was the Kuyper observatory. In this respect I am curious how much better Webb will bee ! It is awesome! I was not clear about the statement " in our part if the universe " . I thought Holland was at the center. ;)
mindblowing video, thank you SO MUCH for showing what you think it'll look like at that wavelength - I'm still expecting the results could be eerie....... interesting stuff!! Best channel on youtube
Alonso & Finn, now those names take me back 25 years, to my time at TU Delft! What I kind of missed in this excellent explanation is that it is possible to increase the aperture of a system by creating an array of telescopes. If done properly, it increases resolution but not the sensitivity. Or, if you go more exotic, you can create a massive slice of an imaginary dish, and increase aperture this way. That would be the RATAN-600 radio telescope.
With NASA’s announcement today of the completion of the JWST’s alignment, I would absolutely love a very (very!) detailed video on exactly what alignment means - their video mentions both spatial and phase alignment, using FFTs, and I can’t think of anyone better on the internet to explain it than Huygens Optics!
I absolutely love your Videos, every time I learn something new and exciting. Can't wait for the next one 😃😃 You are doing a Great job of explaining things in a simple to understand and interesting way. 10/10 🥰
Something with 377 ohms of impedance (so it generates no reflection) but also has resistance to absorb the energy … the basic principle of stealthy radar absorption across the intended frequency range. EM waves are EM waves but materials involved behave different at different frequencies.
@@elderbob100 Some mirrors have the outer edge curve slightly away to make the bulk of the fringe rings be outside the imaging reflection. Black paint is also used, which is no better than a sharp edge, but usually the edge of an astronomical mirrors has worse imperfections at the edge, so it helps.
If I continue to view your videos and supplement that behavior with advanced studies in maths and optics, I'll attain my advanced degree approximately 100 yrs after my death. But I still learn from you. Thank you very much.
An excellent explanation. Thank you. It seems like this would also explain why refractors and schiefspieglers would punch way above their weight when viewing fine detail on planetary objects. Liked, subscribed, and now commented.
Great video, always say cameras are like most things, bigger is better. I am excited about the James Webb because the longer wavelength can see through dust giving us images of things we have never seen.
i wouldn't beleive that this is true ! luckily youtube give me the chance to see your video ( thanks to youtube recommandation) ! and what a humble Man you are! great content ...keep going giving us the knowledge that opens our eyes.
That was a crazy good video! I would add that in quantum theory light is a particle of a given energy where "wavelength" corresponds to the probably of a thing (mirror or camera sensor) interacting with such photon(so reflecting it if a mirror, or absorbing it, if say a CCD) very generally speaking. Thus resolving power is based on how close the optics are to the "Overlap" of probability areas. These probability areas could be imagined as a fuzzy sphere equal to the wavelength of light ..where the closer we are to the sphere center , the higher the probability that photon will be absorbed/reflected etc. for ex: if a detector/mirror is so small that two separate photons landing on it have large overlapping areas , then "which photon" it was can not be well distinguished (uncertainty principle applied to electrons absorbing photons ) so the resolution is low. However all this does not contradict anything you have in the video, it is simply the alternative way to look at it. Keep up the great work.
Very informative and thank you for this. While this telescope is wonderful for many reasons, it is false to assume image resolution beyond what has already been seen. Since James Webb is looking at infrared light, it is important to note the aperture required for comparable image resolution to visible telescopes is much greater even than six meters. The longer the wavelength, the greater the aperture needed for the same resolution. We will be able to see images from infrared light (not in infrared light) which will show us stars and galaxies at greater distances than can be observed in visible light, but we should not think we will see more distant objects with the same clarity Hubble has given us. As for planetary observations within the local galactic group, I think we are in for a real treat. This is where James Webb will excel. Thanks again for this video and for providing input on this issue.
I attended the Christiaan Huygens school in the early 1960s (Rotterdam) for Electronics; they had also optics and clocks&watchmaking as fields of study. Enjoyed this (refresher) course!
I've learned something new from this video. Great illustrations and explanations. If there would be a sensor for the UV part of the spectrum on the James Webb platform, it would give even more angular resolution due to the shorter wavelengths of UV light. I think this could create interesting images.
Some of this reminded me of the filming (photography?) used by Stanley Kubrick in 2001. When filming the models he wanted them to look as convincing as possible (some of these models were huge, there were two models of the spacecraft, one for close-up and the other for long shots, the spherical section of the close-up model was about 8ft diameter and the long model was about 13ft long, the space station was really large, all models bar one [the lunar lander] were destroyed after filming) so he opted for a very deep field of view and thus a tiny aperature, this required an exposure time of several seconds per frame. For moving shots, the camera was on a precise rail system and moved a tiny distance between frames, all automated and unattended. The space station also rotated as well as the camera moving, adding a further degree of complexity. Single short scenes took several hours to film, and days to make sure they were just so. There was a story of a faulty scene using the space station due to an overexcited crew watching a football match in an area adjacent to the studio - apocryphal? One of my favourite parts of the technology aspect of the film was the high tech, beautiful looking, visual displays with their vector graphics (actually back projected 16mm film) right next to nixie tubes. >:-)> - well, it was the sixties, before anyone had landed on the moon, there was only so much you could do!
I wonder what you could get by taking the incredible details you could see on the shorter wavelengths, and analyzing the relative "fuzziness" on the longer wavelengths, combining them if you assume some model of how the sources of the light correlate their emissions at different wavelengths
Can you do a quick video explaining the fringe patterns seen in the recent Webb image now that it is aligned. 1… rays coming out of the star 2… each ray has multiple interference lines 3… the blooming around the star 4… Dim stars look like weird twisted Daisy wheels.
The explanation of the microscope experiment contains a misleading simplification for the sake of understandability. Can you find which simplification that is?
Great video and amazing explanation. You have addressed a very important aspect of the angular resolution of the Webb and clarified that Hubble gives actually sharper images than Webb which previously was not understood and they gave the wrong impression that Webb is sharper than the Hubble. However Webb can collect more light and therefore will have a longer range.
Nevertheless, you did not address that infrared spectrum of Webb is not absorbed so much as visible spectrum of Hubble from space dust, gasses and nebulas. Therefore with the Webb we will seethrough these obstacles which is a very important feature of infrared telescopy.
About the spacing between the mirror segments of the Webb and the diffraction and sharpness problems this can cause? I believe the black substrate material behind the mirrors will absorb all these artifacts.
the way you showed us the wave propagating on screen doesn't make a lot of sense to me. Im not entirely sure how you did that to be honest, was it by changing the focal length?
Explaining that the light pattern outside the aperture looks like a wave because that's the only way light can travel is misleading -- shining a laser across a flat surface wouldn't look wavy, even though it's also traveling as an electromagnetic wave. The wave pattern is an interference effect with the wavelets traveling at the edge of the aperture
@@SodiumNitrateBot Yes, Lucas, spot on. I am suggesting in that part that what you are seeing is the actual EM-wave moving out and inwards, which is of course not true. You are still just seeing diffraction. However, because you can only see diffraction to the point that the field extends, there will still be some relationship between the extend of the energy redistribution and the extend of the diffraction pattern. I left this in to let people discover this themselves. @Alex Domatas the patterns are recorded by changing the focal position of a microscope with a very shallow depth of focus. In this way you can observe what happens at a specific "slice" of space. I used this same method in previous videos such as the one on Photon sieves.
I’m not aware of any other UA-cam channel that has your combination of approachability for an optics beginner like me, combined with depth of technical detail if I make the effort to study it. Thanks so much, and please keep the videos coming.
I can only 2nd this! ^^
Thank you Huygens Optics!
Truth
I third this! Thanks from Australia :-)
Perfectly put
Me too
"This principle is far more often explained, then it is really understood" love it.
Haha, yea, I caught that too. There's a lot of low-key jokes in these videos.
Most schools of engineering are like that, these days. Simply focused on cramming as much information into a students head as possible without regard for actually understanding it.
So it is with many principals, physical and otherwise.
I couldn't agree more than that ! ( very agree )
That was a fantastic turn of phrase.
Living in Tucson Arizona and surrounded by a large astronomical and optical research community I have had the opportunity to talk with many optical researchers and astronomers. You sir have an exceptional ability to communicate the science of optics. I appreciate your efforts and hope you continue as I have learned a great deal from your videos. cheers
A fellow Tucson resident on this channel! It shouldn't be surprising but for some reason it just makes me happy
@@colinbrown7947 Third Tucson Resident here, and it does indeed make me very happy. The Tucson Optics community is great.
Im a hobbyist in tucson. What approachable communitys do you all speak off? I got an 8" dobsonian and some great books, but i need more stellar friends!:)
@@briank592 Tucson Amateur Astronomers (TAA) is a great place to make connections and get started.
@@professorbellorum Thank you for your direction!
Your videos are always great! Yes, I'd be interested to know about segmented mirror telescopes. It does seem like diffraction would be a problem. Maybe they use similar tricks as semiconductor masks?
I believe they are very similar. The reconstruction techniques seem to share Fourier ptychography as an ancestor or cousin.
Thanks Ben. Yes, as long as the diffractive edges are regularly spaced, they represent a very specific frequency component in the Fourier transform. I'm not aware of how exactly they do it, you could imagine that it is some kind of low-frequency spatial filtering. That might also explain why the outer perimeter of the mirror has an hexagonal shape and has not been rounded. Because only then it the same filter can be used for both segment spacings as well as the edge.
@@HuygensOptics would this filtering be done in software then? How is it done for chip masks?
@@LarsBerntzon In chip masks it works differently. The precise mask pattern is actually irrelevant, it's only about the light distribution at the photoresist layer. So you use computational methods to optimize this intensity profile by using specific diffraction effects and write the patterns to achieve this onto the litho mask.
@@HuygensOptics Ah, I see. So if we could go to the end of the universe and place a really big specially crafted mask there we could get really good images in our telescopes :)
I got a master's degree specializing in electromagnetic wave propagation and your explanation of the physical cause of edge diffraction is the best ever! It really brings together the mathematics and real world observations. And yes, what you show as "waves" in the microscope image are actually interference patterns, not the actual light waves. This is a good way to visualize what is going on with the energy transfer.
I had most of this material at the university in a course on industrial imaging, at the time it was quite fascinating and i am surprised how much i put it to use working.
It is so much fun to watch these videos and gain more info and insights on these topics. The quality of content you make and put out there for free is really astonishing. I cant thank you enough!
I digress, the second half of the video is the most fascinating thing i have seen this year. :D
I would have loved to have this person as my teacher at the University. It does not matter how hard or complex the topic is, he always finds the way to make it extremely attractive to me... and I am just totally ignorant when it comes to physics or optics. Chapeau!
Agreed!
Most instruments on JWST are sensitive to the near infrared at wavelengths
Wait, is there a reason why they wanted a comparable resolution?
@@Emenblade may be this is the reason why he is now a former optical engineer and full time conspiracy theorist
@@Emenblade I can imagine that when they were deciding the budget for JWST somebody told them "ok, we can give you enough money to make a telescope as good as hubble but in infrared, you are saying that it is a hubble replacement anyway, just in infrared, alright? We won't fund anything bigger than that".
@@TheoEvian Because the first object from JWT to be posted on Reddit will be compared side by side to the image from Hubble, and every crackpot will claim JWT is a waste of money as it produces worse images. So I guess NASA cares about Reddit Karma?
@@Tore_Lund They do care about PR quite a lot but I don't think that would be the main reason. As I said, I can imagine the image quality being a part of the budget negotiations.
Just gotta say, I love this channel much. Plenty of other channels offer shallow takes on similar topics, but this is the only channel I know that really dives deep into the subject of optics, and presents in a manner that most people with an interest in science can learn from. Thanks so much for taking the time to make these videos.
After several weeks of James Webb news, I needed a fresh dose of Huygens Optics. Your videos are so well made that an interested novice, like myself, can follow along.
Ooooopssss there goes resolution in the deeper infrared.
That was a remarkable clear and visually superb illustrated explanation, understandable for a layman like me.
LOVED IT 💯!
Indeed. Not an oops though, it Is highly specialized and likely hundreds of hours were poured into deciding exactly where to focus our instrumentation. You can not have it all, and in this case they preferred to Have great balance between visible and infrared. Rather than deep infrared only without any visible light
I've never considered why wave behaves like they do and your video gave me a greate intuition about it!
This is super food for thoughts.
Thanks
Great explanation of these concepts. If you read any of the blogs on photography or cameras, you will be amazed at the
confusion amongst photographers on the topic of "resolution" of lenses.
Modern day photographers are remarkably ignorant about how their cameras work considering how easy it is to find information on the internet
This video is much more intelligent than UA-cam deserves.
In the sea of videos trying to explain Webb ST. This one is absolutely the best. (From what I have seen so far)
Your explanations have a very large aperture, they are crystal clear !
A remarkable presentation filled with teaching and discussion RE:JWST. As long as you identify fundamental limitations to optical performance, JWST will be 'seen' as remarkable with potentially new scientific data for cosmologists. Without belaboring points, a larger mirror could not have been launched today and high red shift demands longer wavelengths. JSWT will (hopefully) collect the only available photons from high red shift objects - full stop. Your video is one of the most well prepared and rigorous I have ever seen; I particularly like the energy discussion. I will review Feymann's lectures again to compare with your presentation.
Explaining the Huygens-Fresnel diffraction principle as an exchange of energy, is mindblowing! Now I even understand EM waves better too!
I appreciate the clear diagrams and pause your videos many times to study them.
I've been working in optics for almost a quarter century, and I have to say that this guy has a gift at explaining things. I'm a little envious, actually.
Very nice Video! I am working in the field of optics and I got some amazing new perspectives from your videos. I think another advantage of the longer wave length of the James Webb telescope is that you can observe through dust which is not possible with visible light.
Yep, that's one of the reasons NASA indicates for going IR - to get through the dust. However, after watching this video, I am a bit puzzled.
Or you can look at it in terms of a spatial Fourier transform, translating between position and k-space. The spatial profile between the aperture/lens/mirror and the focus can be described by a fractional Fourier transform. This then tells you, that the k-vector distribution created by the round aperture in front of a lens makes a focus which is its Fourier transform, an Airy disk.
Sure. But this would also have significantly reduced average viewing duration.
@@HuygensOptics Speaking of Fourier, would it make sense to make apertures with Gaussian or raised cosine edges? E.g. via gradient in optical density? Those would result in less ripple. Another question - just like we use equalisation in digital communication, would it be possible to compensate for some of the distortion caused by the finite aperture using digital filters?
You just delivered the single best explanation to why a pinhole lens has an optimal diamater. I always heard, that diffraction causes the image to get less sharp if you have an apperature that is too small, but I never really understood why. Your graphics really helped me too wrap my head around it. Such a great Video!
Thank you. That was the first time I understood the difference between Hubble and Webb’s capabilities.
Thank you for making this video - it's extremely informative.
I am working on my PhD in Astrophysics, and you're still educating me.
The surface-tension analogy and explanation for the Huygens-Fresnel principle was particularly eye-opening.
A rare for-grownups content presentation. You feel taken seriously when listening to this.
That explanation really came together at the end and made perfect sense.
It seems like it should be possible to set limits on the possible granularity of spacetime by looking for gaps in the stretched wavelengths.
Thank you for the thorough going over on aperture.
[off topic] as a nerdy macro photographer, I just love THIS explanation of diffraction
Chapeau!
Als iemand die halverwege de middelbare school natuurkunde liet vallen, nooit de uni heeft betreden, en later pas astrofotografie heeft opgepakt... moet ik zeggen dat ik de uitleg en combinatie met praktijk beelden super overzichtelijk en begrijpelijk vind. Goed werk!
Jeroen: Thank you for this video. It has let me add your astute observations on diffraction to my own patchwork of understanding. And I appreciate your sharing your extraordinary optical creations through your other videos. You are making an outstanding contribution to the world wide web!
I am fascinated by your clear and detailed explanation of the role of the diffraction limit on resolution. The last time I was dealing with it has been 45 years ago in the advanced internship (Fortgeschrittenen-Praktikum) physics studies. Since then I wondered that endoscopes and miniature cameras of mobile phones were able to supply such good images as never going into details. Now suddenly by following your video I experience more clarity. It is a great pleasure!
The presenter pans across a lot of physics, not just optics. The presentation is so well thought through that a lot of difficult concepts get explained so ordinary mortals can understand.
Max kudos!
But should we be surprised at the Dutch who currently (Q3/2023) have Robbert Dijkgraaf as Minister of Education. Dhr Dijkgraaf is an internationally known theoretical physicist, former director of the Institute for Advanced Study at Princeton (a role taken by Robert Oppenheimer in the 1950s). So brain the size of a planet, close enough - education in good hands.
Thank you for the energy concept of wave diffraction. I find it much more intuitive than the geometric concepts.
This is the only video on youtube that actually explained Diffraction so effectively that I can't even express. Now I know why everyone says don't shoot above f11 with most lenses because smaller the size of aperature the angle at which the incoming light will diffract so severely that most of it won't fall on sensor so less resolution/softer images. Also Thank you sir for that JWST explanation I was commenting everywhere saying the apparent resolution of JWST is basically even lower than hubble But so many people are just waiting for the images. Also IR is the reason why JWST has only 2MP sensors in its cameras to help it get as light as possible & not care about resolution as much as there is literally no way anyways.
NIRCam instrument consists of an array of ten 2048x2048 px sensors, so it's roughly a 40 MP imager. Furthermore the optic correction capabilities of JWST are far better than those of Hubble. Given it can work up to 600 nm (visible orange), it will provide high resolutions images, even if these will not give the most scientifically relevant results.
@@robcavazz Thats what I don't think they would have designed & made such a masterpiece if it e=was not even higher resolution. Guess all have to wait and watch which turns out to be true. But being an engineer myself I have immense amount of faith in the engineers who designed all of jwst the optics[USA guys] & ofc Instruments[Canada guys]. BTW do you know how they will add all the colors like the colors closer to blue in wavelengths? Which techniques? Also is it same for IR & Far visible range or it differs?
I thought about this issue with the wavelength and resolution and hadn't seen it addressed yet, so thank you for that!
One of the best discussions on this topic I have ever seen.
Excellent video! Diffraction is one of the most hermetic phenomena in light and you always make it reach the edge of grasping it. Fascinating subject!
When you describe the effect of relaxing boundary conditions, you're correctly describing the physics of diffraction. But I would argue that Huygen's principle denotes something more specific, even though I agree that this isn't always understood when people present it as if it were an exact description of nature. Huygens gave an approximate description of (linear) wave propagation that has one fundamental physical ingredient: the superposition principle. This ability to form superpositions makes it possible (a) to consider every point as the source of a "spherical wave," and (b) to reconstruct the wave at any other point from the spherical-wave contributions that originated at other points. To do this right, you have to do certain integrals (using Green's functions). The construction in Huygens' principle is an approximation to this method that captures the main phenomena reasonably well (in three dimensions, but ironically not so well in two).
First video I have just seen of you and can just hope, you teach other people in some way other than youtube. Man this was spot on explanation and new information without the bla bla around other stuff!
Thank you for this. I love learning new things and you do a great job of explaining complicated concepts.
So informative. I felt like I just absorbed a lecture without feeling the chore of a lecture.
I hate to say it but this video has deflated a bit of my excitement for jwst. Up until now I had the idea in my head of jwst being able to literally zoom further out, and to be able to resolve those more distant objects just as well as Hubble. I have been imagining resolved images tracing the first stars ever born, and then being able to watch step by step as they coalesce into galaxies. This video has made it clear that we won’t be getting those images. I get that there is still an immeasurable amount of new science sure to come from the observatory, I’m just a bit bummed that the super-mega-ultra deep field of my minds eye is likely still one or two generations of space telescopes out…
That is something that has always frustrated me about the science journalism surrounding the James Webb. It has always been sold as a bigger/better Hubble, but it's not. It's an instrument with a totally different purpose. I have been worried for years that the general public might be disappointed when it "fails" to generate "better" results.
Nothing against JWST. Just 100% a failure to explain what the goals and capabilities are. Which is a shame.
@@martinmckee5333 Most journalists aren't paid enough to care about anything. Most articles are written on short deadlines by people not qualified to write them, while they are working on several other similar articles besides.
Under these circumstances, it's not surprising such incredibly poor coverage is given to every subject.
@@lobsterbark Not surprising, no. But still disappointing. I'm convinced that the quality of science journalism (or lack thereof), is a big reason for the current lack of excitement in and outright distrust of science by the general population.
Eon space labs is doing great. Really impressed with their work in very short time and limited resources. Keep doing good job Team Eon Space Labs (ESL).👏👏👏
And here I was, all hyped up for some amazingly sharp pictures from the Webb's telescope.
An excellent explanation for people whithout deep knowledge for telescopes. I learned some unique stuff.
"When the pro speak". Thanks you for sharing your knowledge
I would be fascinated by a video describing the methods that the JWST uses to compensate for the gaps between the primary mirror segments.
It's the same principle as why you don't see the obstruction by the secondary mirror and the arms that hold it, they are not in focus. They form, in the worst case scenario, if the gaps were very big, a slight gradient on the image. (but I'm sure mr Huygens can explain it better). edit: it could be that they cause some weird difraction spikes on very bright stars, not sure about that.
@@forton615 yes, the spikes on near stars give away the geometry of the secondary mirror support arms
This is not the first video from your channel that I see, but even more than before I'm mesmerized! You deserve millions of subscribers. Thank you very much for this amazing content!
Great great great video! I didn't even know how curious I was about this stuff. Your voice is super relaxing and you're so informative, too. We received a little 80mm aperture hobby telescope for christmas,and are already looking at others after seeing the moons of Jupiter.
So very good! You've cleared up things I thought I knew clearly before.
That video explains this subject so well and is so interesting! Really pleasant to watch 😀
Superb presentation, especially about the edge effects of spreading both inwards and outwards, I've never seen that explained so clearly. Thankyou
I agree with the position of explaining light in the same manner as we would any other form of energy. Very good video my good sir, thanks for making this. As per typical with your content I find my self learning about something that I didn't even consider was a thing to learn.
Very nice to understand the optical limitations of James Webb.
Good video. I am an amateur photographer.
The facts laid out here are the reason, that people claiming "My phone does just as good pictures as your big camera" drive me mad.
This was an AMAZING reveal of optics down to the quantum level. Very thought provoking!
As a simple viewer of this fascinating field of science, combined with your capability to communicate these complicated terms in a way simpler mood, is outstanding. With this background on my side, my expectations for the web space telescope were rather *BIG*... but you let me look better at the physical reality.
I'm a bit sad, but THANKS!
What a beautiful video!!! I would have loved if you teased the fact that you are going to give such a good explanation at the end, I was really frustrated at the beginning because you said a lot of things that are so and so, and you made no indication that you will explain later. I got instantly so curious that I stopped the video in 1/4 going to look elsewhere for answers. After a quick look at the comments, I came to the conclusion that you actually will explain, and I just need to be patient. :)
Also for me, the key was first understanding the intuition, then the formula, that order would feel more natural to me. :)
Thank you so much for these videos, I was incredibly curious about diffraction at boundaries for a long time and no physicist I talked with was able to give me an explanation I was happy with. Great insights!
I love your explanations! They are so clear and interesting. I'm very excited to see what the Webb telescope will show us. I have a distinct memory of getting mild vertigo years ago watching a slow zoom in on some part of the deep field image and realizing that all those "stars" were actually galaxies. Thanks for your care in making such good sciences content.
Now I fully understand why a big telescope or microscope means better resolution!! Thank you!!
Excellent video explaining hard to grasp concepts!! Bravo!!
Thank you for this extremely clear explanation. I find that experiments like Webb and Ligo are truly physical science marvels. There was, I believe, and still is an infrared telescope aboard a large aircraft flying at roughly 12 km. The older one was the Kuyper observatory. In this respect I am curious how much better Webb will bee ! It is awesome! I was not clear about the statement " in our part if the universe " . I thought Holland was at the center. ;)
SOFIA, Stratosphere Observatory for Infra-Red Astronomy, a joint NASA/ DLR Project flies out of Southern California.
mindblowing video, thank you SO MUCH for showing what you think it'll look like at that wavelength - I'm still expecting the results could be eerie....... interesting stuff!! Best channel on youtube
YAY, made my month to see another video.
Alonso & Finn, now those names take me back 25 years, to my time at TU Delft!
What I kind of missed in this excellent explanation is that it is possible to increase the aperture of a system by creating an array of telescopes. If done properly, it increases resolution but not the sensitivity.
Or, if you go more exotic, you can create a massive slice of an imaginary dish, and increase aperture this way. That would be the RATAN-600 radio telescope.
This is my first time finding your channel, but I'm definitely impressed!
With NASA’s announcement today of the completion of the JWST’s alignment, I would absolutely love a very (very!) detailed video on exactly what alignment means - their video mentions both spatial and phase alignment, using FFTs, and I can’t think of anyone better on the internet to explain it than Huygens Optics!
I absolutely love your Videos, every time I learn something new and exciting.
Can't wait for the next one 😃😃
You are doing a Great job of explaining things in a simple to understand and interesting way. 10/10 🥰
Every new video you publish is such a treat for my brain. Thanks!
Could you add some form of impedance matching structure at the boundary of the aperture to improve energy coupling and reduce reflection?
What like some material with different speed of light in it?
@@PurpleVidaar Or an energy sink.
I had a similar idea. A half inch strip around the front edge of the mirror that starts out clear and gradually turns black.
Something with 377 ohms of impedance (so it generates no reflection) but also has resistance to absorb the energy … the basic principle of stealthy radar absorption across the intended frequency range. EM waves are EM waves but materials involved behave different at different frequencies.
@@elderbob100 Some mirrors have the outer edge curve slightly away to make the bulk of the fringe rings be outside the imaging reflection. Black paint is also used, which is no better than a sharp edge, but usually the edge of an astronomical mirrors has worse imperfections at the edge, so it helps.
Excellent explanation for non expert viewers!
Thanks for your explanation.It makes me understand more of the world itself.
If I continue to view your videos and supplement that behavior with advanced studies in maths and optics, I'll attain my advanced degree approximately 100 yrs after my death. But I still learn from you. Thank you very much.
loved the explanation of angular resolution.
An excellent explanation. Thank you. It seems like this would also explain why refractors and schiefspieglers would punch way above their weight when viewing fine detail on planetary objects. Liked, subscribed, and now commented.
Great video, always say cameras are like most things, bigger is better. I am excited about the James Webb because the longer wavelength can see through dust giving us images of things we have never seen.
Very cool approach to Huygens principle.
And now I also know it's pronounced Huyxens.
i wouldn't beleive that this is true ! luckily youtube give me the chance to see your video ( thanks to youtube recommandation) ! and what a humble Man you are! great content ...keep going giving us the knowledge that opens our eyes.
That was a crazy good video!
I would add that in quantum theory light is a particle of a given energy where "wavelength" corresponds to the probably of a thing (mirror or camera sensor) interacting with such photon(so reflecting it if a mirror, or absorbing it, if say a CCD) very generally speaking. Thus resolving power is based on how close the optics are to the "Overlap" of probability areas. These probability areas could be imagined as a fuzzy sphere equal to the wavelength of light ..where the closer we are to the sphere center , the higher the probability that photon will be absorbed/reflected etc.
for ex: if a detector/mirror is so small that two separate photons landing on it have large overlapping areas , then "which photon" it was can not be well distinguished (uncertainty principle applied to electrons absorbing photons ) so the resolution is low. However all this does not contradict anything you have in the video, it is simply the alternative way to look at it. Keep up the great work.
Very informative and thank you for this. While this telescope is wonderful for many reasons, it is false to assume image resolution beyond what has already been seen. Since James Webb is looking at infrared light, it is important to note the aperture required for comparable image resolution to visible telescopes is much greater even than six meters. The longer the wavelength, the greater the aperture needed for the same resolution. We will be able to see images from infrared light (not in infrared light) which will show us stars and galaxies at greater distances than can be observed in visible light, but we should not think we will see more distant objects with the same clarity Hubble has given us. As for planetary observations within the local galactic group, I think we are in for a real treat. This is where James Webb will excel. Thanks again for this video and for providing input on this issue.
I attended the Christiaan Huygens school in the early 1960s (Rotterdam) for Electronics; they had also optics and clocks&watchmaking as fields of study. Enjoyed this (refresher) course!
I presume his lectures were full of skirts? Huygens was 9 magnitudes more dandy than Fresnel!
Again a superb video. Congratulations!
Wonderful video. It would be interesting to hear a discussion about the interferometry techniques used by James Webb as you mentioned it.
congratulations on the attention. you guys deserve it it's a kick ass idea.
I've learned something new from this video. Great illustrations and explanations. If there would be a sensor for the UV part of the spectrum on the James Webb platform, it would give even more angular resolution due to the shorter wavelengths of UV light. I think this could create interesting images.
This is a fantastic explanation, thank you.
Thank you for this explanation of the relationship.
Well done. As someone who ground his own 6" Newtonian mirror in 1969, this is both familiar and new to me.
cheers from sunny Vienna, Scott
Wow. What a great demonstration.
Some of this reminded me of the filming (photography?) used by Stanley Kubrick in 2001.
When filming the models he wanted them to look as convincing as possible (some of these models were huge, there were two models of the spacecraft, one for close-up and the other for long shots, the spherical section of the close-up model was about 8ft diameter and the long model was about 13ft long, the space station was really large, all models bar one [the lunar lander] were destroyed after filming) so he opted for a very deep field of view and thus a tiny aperature, this required an exposure time of several seconds per frame.
For moving shots, the camera was on a precise rail system and moved a tiny distance between frames, all automated and unattended. The space station also rotated as well as the camera moving, adding a further degree of complexity. Single short scenes took several hours to film, and days to make sure they were just so. There was a story of a faulty scene using the space station due to an overexcited crew watching a football match in an area adjacent to the studio - apocryphal?
One of my favourite parts of the technology aspect of the film was the high tech, beautiful looking, visual displays with their vector graphics (actually back projected 16mm film) right next to nixie tubes. >:-)> - well, it was the sixties, before anyone had landed on the moon, there was only so much you could do!
Once in a while you stumble across a video for which a simple like-button just isn’t enough.
Would love to see a video about what you think the spectrums analyzed would look like, and the possible discoveries that many are predicting
Thank you for this video, it was very interesting and educational.
I leaned a ton from this video. Thank you!
I wonder what you could get by taking the incredible details you could see on the shorter wavelengths, and analyzing the relative "fuzziness" on the longer wavelengths, combining them if you assume some model of how the sources of the light correlate their emissions at different wavelengths
A wonderful explanation.
Can you do a quick video explaining the fringe patterns seen in the recent Webb image now that it is aligned.
1… rays coming out of the star
2… each ray has multiple interference lines
3… the blooming around the star
4… Dim stars look like weird twisted Daisy wheels.
Would love to hear how wavefront sensing works for telescopes that have to align multiple mirrors!
Given such wavefront sensor data is precise enough, could one maybe simulate an enormous telescope using an array of very small telescopes?