Microscopy: Point Spread Function (Jeff Lichtman)
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- Опубликовано: 3 июл 2024
- Learn more: www.ibiology.org/talks/point-...
An infinitesimally small point appears in the microscope as a spot with a certain size, blurred in the z-direction and with concentric rings around it. This "point spread function" reveals many of the optical properties of your microscope. This lecture explains why and how the microscope images a point as a point spread function. 
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Ho my... Thats got to be one of THE MOST didactic video about PSF's... Although the channel is about biology, the optics explanation is better than most of the optics specialized videos. Congratulations! Thank you for sharing this!
Very clear lecture! Thank you for making it easy to comprehend!
Inspirational! This very important but challenging subject is rendered so clear and interesting by someone who understands it inside-out but is still able to project into the minds of those who don't. It's also extremely humble. Jeff Lichtman has made major contributions to our understanding of the brain by advancing imaging technologies and yet he resists the temptation to refer to his work (not even using his beautiful images as examples). Thank you for this masterclass in teaching!
If you also are using the light microscope for your brain research, kindly pass on any tips or tricks novices might find useful when undergoing their ow experimental beain research via bright field microscopy. Thank you in advance (RUclips videos are an extremely wonderful communication medium for any such informative videos.).
This video renders the highest resolution ever for Diffraction and PSF; you are a great educator Professor Lichtman; a thousand thanks...
REALLY FANTASTIC LESSON!!
Amazing lecture! Thank you very much!
Very good lecture! Thanks
Thanks for the clear explanation. It was very useful.
Best explanation ive seen!
Fantastic! Thanks a lot for the clear explanation :)
Great talk. Thank you very much.
clearly explained the PSF. Thanks a lot.
Great video! very understandable, thanks for sharing. Also it would be nice if Jeff could look at the camera.
As a side item, this lecture also shows well why resolution is inverse to depth of field.
wonderful explanation.
Amazing video! :)
P.s.f. is for only point sources. Edge spread function describes lines or extended sources.
25:30, how does he get 225 from 0,61 * 480 / 1,4 ? Am I missing something or is it wrong?
Interesting course about Psf , interference and numerical aperture (NA)
The smaller NA , the wider Psf , the larger NA the smaller Psf
Frederic HEHN MD
Very good!thnks!
Brilliant insight at explaining the nature of PSF. There is one point though I couldn't catch: the difference between the diagrams at 20:30 and 22:25 showing the axial intensity distribution of the PSF and the bottom diagrams at 25:00 also showing the axial intensity distribution. Diagrams at 20:30 and 22:25 clearly show an axially intensity distribution while it is in the diagram at 25:00. Why is it so?
Good question. I also wondered, why Prof. Lichtman showed such PSFs in his simulations. I think the reason the PSFs at 20:30 and 22:25 show the axial asymmetry is that they were computed for a spherical tube lens which is far away from ideal imaging conditions because any spherical lens introduces spherical aberrations. This spherical aberration is just the axially asymmetric pattern shown first. The in the end of the lecture, Prof. Lichtman unfortunately does not tell us, that he now shows ideal PSFs generated by aspheric lenses - which is way more common in high-NA microscopes. To be honest, I do not understand why he started with aberrated PSFs in the first place especially without mentioning the aberration occuring.
Even though I said that the ideal PSF shown in the end is closer to the PSF of a high-end microscope, please be aware that this is only the case if the sample and the immersion medium have a matched refractive index. If this is not the case - e.g., as when imaging biological samples with refractive index n of about 1.4 with an "air-objective" (n = 1, no oil, glycerin, water or whatever between sample and front lens) - you will end up with a PSF that looks just as the one shown at 20:30.
To put things right: I think this video excellently introduces the PSF in a very clear way! My remark is no criticism but only a humble attempt to answer a given question. Thank you for your great efforts in producing this educative video!
at 7 minutes, the diagram shows the waves that will interfere in antiphase (due to mirroring one waveform to make the other?) When the set for point D2 is shown, they are shown in phase on the rays, but should be antiphase. I had a couple students ask me about this. The ray diagram has one set (upper or lower) flipped. The diagrams to the right showing the interference are correct.
+john john It may simply be related to the choice of the origin: if one choses the origin at the point between the two wavelets then the bottom wavelet is "negative antiphase", thus in phase with the top one. I assume that these two waves are merely a representation to illustrate wave propagation, what is important are the diagrams on the right.
How do you plot those images in the XZ plane?
At 15:05 wouldn't the red wavelength be 780 nm instead of 580 nm (green-yellow)?
Applicable lastname, lightman in Dutch
DOPE!
With his name he must be an expert ;-)
Nice lecture but you repeated 90% of this in previous ones