> "Lucky imaging" is not a widely used technique in astronomy
True, but it is very popular in astrophotography.
Also, there are many recent advances in super-resolution imaging, compressive sensing, and sub-diffraction-limit pixels, often based on results from Donoho, Candes, and friends. Taking advantage of signal sparsity (i.e. that the set of physically possible signals is much smaller than the set of all possible signals, and physical systems have many constraints upon them) has led to a lot of surprising results over the past 15 years or so. Another approach that has yielded results is aperture synthesis, which has been applied to optical systems for at least the past 15 years. And in some certain circumstances for spysats, optical heterodyne detection can also be used to great effect.
> you are always going to be limited by the diffraction limit of the telescope
While the diffraction limit of a system is definitely a constraint, it's not as simple as this anymore.
Aperture synthesis, aka interferometry, has been applied to optical systems for far more than 15 years. The Narrabri Stellar Intensity Interferometer[1] saw first light in 1963, for example. However, your resolving power is still fundamentally limited by the distance between your telescopes. The diffraction limit may be more of a fuzzy limit than a hard cut off, but it is fundamental physics. Optical interferometry is hard, and you don't get a image in the way that most people would think of it. To build up a detailed image with aperture synthesis requires measurements over a very large number of baselines.
Yes, agreed. In fact, the first example I can think of is the Michelson stellar interferometer at the Mount Wilson Observatory, which was in operation in 1920.
However, there has been a major push recently to circumvent the limitations of optically connecting the telescope arrays; there are a few different approaches, of which I'm not aware of any fatal flaws. Seems likely it's a matter of time and physics and engineering; very difficult, but achievable.
True, but it is very popular in astrophotography.
Also, there are many recent advances in super-resolution imaging, compressive sensing, and sub-diffraction-limit pixels, often based on results from Donoho, Candes, and friends. Taking advantage of signal sparsity (i.e. that the set of physically possible signals is much smaller than the set of all possible signals, and physical systems have many constraints upon them) has led to a lot of surprising results over the past 15 years or so. Another approach that has yielded results is aperture synthesis, which has been applied to optical systems for at least the past 15 years. And in some certain circumstances for spysats, optical heterodyne detection can also be used to great effect.
> you are always going to be limited by the diffraction limit of the telescope
While the diffraction limit of a system is definitely a constraint, it's not as simple as this anymore.