For context, I'm a software engineer, and when thinking of fixing CA using software, I came to the conclusion that it was impossible because the aberration is light that is actually out of focus, so infirmation is lost when photons hit the sensor (the direction is partially lost). So to be able to fix it, we need it to be focused, and that's when more optical surfaces come into play...
The thing is the challenges of triplets and more are still a thing, I was thinking that if the beam can be splitted and frequencies focused and processed by themselves, we could use high quality glass cheap doublets with tbis reusable complex part, makimg it convenient in tje case of a. 300mm doublet tvat is payable, unlike a 300mm APO... In tje same page, the same beam splitter could be used with a 400mm and a 3000mm, potentially lowering the total cost (400mm APO + 3000mm APO vs 400mm doublet + 3000mm doublet + splitter) and being able to push the current limits... I'm just trying to find if it's worth making the experiment myself with some cheap chinese doublets, filters and ccds... Apparently it does
As I understand it, you propose to use beam splitters to separate the light into a number of individual colors and then sample them individually and recreate the images from the separate colors digitally. I see a number of issues that make this impractical.
- Each beam splitter reduces the transmission by a factor of two. This represents a large loss of light.
- Each color will need to be aligned and focused individually. Focus depends on temperature. This is a nightmare, focusing just one optic is difficult as focus shifts throughout the night. It's hard to imagine focusing multitple sensors.
- Refractors suffer from field curvature and the difference in focal length of the various colors (this is what chromatic aberration is), depends on the focal length of objective. With each objective swap, you would have to realign and refocus in significant way.
- Field curvature means that the edge of the field is not in focus when the center is in focus. This is a function of focal length. Each time you swap objectives, you would need to swap the field flattener optics. This is tricky and time consuming.
- Besides light, resolution would almost certainly be lost.
- Inexpensive achromats suffer more than just chromatic aberration..
It seems like a very complex optical system that is compromised in a many ways. besides the beam splitters, there will be numerous microstages and mirrors all mounted on an optical bench and these will be relatively large mirrors because they have to be larger than the focal plane.
Realize, all this optics has to be placed before the focal plane so you will be working with a relatively large beam that is not in focus.
All this to avoid using better quality glass.. Or as Geza said, why not just use an mirror? a Newtonian is perfectly corrected for chromatic aberration.
One rule of thumb in optics is to keep it as simple as possible, each element adds aberrations. Quality refractors are much better than diffraction limited. That means they provide an image that is perfect to a small fraction of a wave length of light.