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No matter what you do, you still have to deal with diffraction [1], which means the resolution is inversely proportional to the aperture. I think the Trump/Iran
by bobmoretti 6y ago
No matter what you do, you still have to deal with diffraction [1], which means the resolution is inversely proportional to the aperture. I think the Trump/Iran release was estimated to be pretty close to the diffraction limit.
[1] https://en.wikipedia.org/wiki/Angular_resolution#Explanation https://en.wikipedia.org/wiki/Angular_resolution#Explanation
- ridgeguy 6y agoHow about optical interferometry? IIRC, this can beat the diffraction limit.
- greglindahl 6y agoOptical interferometry means you have a wider telescope. Same limit formula.
- mturmon 6y agoYes, but the aperture of the interferometer is no longer limited in the same way, so we could say that interferometry gets around the “naive” diffraction limit.
- cryptonector 6y agoWell, but if you have a bunch of these in orbit, able to image the same site, at the same time...
- CalChris 6y agoYep. angle = k (wavelength / diameter) And the diameter is going to be limited by the launch vehicle. But multiple satellites could improve this.
- stefanpie 6y agoJust took a radars course and we definitely spent a whole section on just atmospheric effects / defraction. My only guess about how you could maybe lower the error is by monitoring and measuring the condition of the atmophere and building a model that can use that data to apply corrections and reduce error to your image.
- TheSpiceIsLife 6y agoIf there was a known object in an image could a high resolution image of the known object be used to compensate for atmospheric diffraction effects?
- bronson 6y agoOne example is a laser guide star: https://en.m.wikipedia.org/wiki/Laser_guide_star https://en.m.wikipedia.org/wiki/Laser_guide_star
- cartoonfoxes 6y agoYes. Ssshhh.
- xioxox 6y agoAs I mentioned above, there is a technique called lucky imaging, where you take lots of short exposures and only use the best ones. In astronomy, this can be used to reach the diffraction limit. You need a bright source, however, and it provides a narrow field of view.
- craftinator 6y agoAnother technique is to use multiple camera sources spread out over an area. The angle between the cameras is known, so differences in the images caused by diffraction and atmospheric aberrations can be computed out to some degree.
- jwiley 6y agoCan you expand on "the Trump/Iran release was estimated to be pretty close to the diffraction limit"? What is this in reference to?
- spacefearing 6y agohttps://mobile.twitter.com/realDonaldTrump/status/1167493371973255170 https://mobile.twitter.com/realDonaldTrump/status/1167493371...
- aiiane 6y agohttps://www.npr.org/2019/08/30/755994591/president-trump-tweets-sensitive-surveillance-image-of-iran https://www.npr.org/2019/08/30/755994591/president-trump-twe...
- dylan604 6y agoI think your question was misunderstood, as the other replies do not go into any details on diffraction limit at all. I too would be interested in knowing if this image is showing all we got, or because someone else looked at it and said "sure you can release it, we've got better than that anyway."
- echelon 6y agoCan multi-camera/multi-view photogrammetry defeat this limit and create super-resolution imagery?