5 ms·
Can that be overcome with computational photography?
by flyinglizard 6y ago
Can that be overcome with computational photography?
- nitrogen 6y agoI'm neither an astronomer nor an imaging expert, but I've read that ground-based telescopes use "lucky imaging" plus deformable mirrors to work around atmospheric distortion. Maybe something analogous works in the reverse direction.
- de_watcher 6y agoFor deformable mirrors they shine a control beam into the sky. A spy satellite would have to shine it downwards.
- krisoft 6y agoCan you use a known object which is illuminated by the sun?
- rocqua 6y agoGiven that people have called this 'wavefront based correction' I would guess you need light source where all photons are 'in phase' like a laser. The sun is not such a source. However, I do not know near enough about physics to say the above with any degree of confidence.
- bobmoretti 6y agoNo 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?
- mturmon 6y agoOptical interferometry has been used to synthesize very large apertures in ground based experiments (e.g., https://en.wikipedia.org/wiki/Palomar_Testbed_Interferometer https://en.wikipedia.org/wiki/Palomar_Testbed_Interferometer). That was in the mid 1990s. Operational ground interferometers have obtained 5 mas resolution, which corresponds to sub-mm resolution from an orbital platform. You still have atmospheric turbulence, but do we know how to get around the naive diffraction limit.