You don't need to make them APO on a wide spectrum. Scientific data is usually taken using pass band filters. You could even have a barlow for each filter.
Exoplanet surveys are mostly done in infrared, so you just need a good lenses for IR.
You don't need to make them APO on a wide spectrum. Scientific data is usually taken using pass band filters. You could even have a barlow for each filter.
Exoplanet surveys are mostly done in infrared, so you just need a good lenses for IR.
What's the lambda for exoplanets? 1000nm? 3000nm? Can you do it with a normal sensor or you need active cooling?
Is it about right that for 1000nm I would need a 27m aperture to resolve an Earth sized planet at 10ly?
You don't need to make them APO on a wide spectrum. Scientific data is usually taken using pass band filters. You could even have a barlow for each filter.
Exoplanet surveys are mostly done in infrared, so you just need a good lenses for IR.
What's the lambda for exoplanets? 1000nm? 3000nm?
There is no special wavelengths for exoplanets. Different investigations work better at different wavelengths.
Can you do it with a normal sensor or you need active cooling?
It depends. :-) Also, we use a lot of passive cooling even in Earth orbit. JWST will passively cool its structure to 40K.
Is it about right that for 1000nm I would need a 27m aperture to resolve an Earth sized planet at 10ly?
Are you imagining real resolution, with critically sampled PSFs smaller than the exoplanets? This wont even be an issue until we have such targets. (I have not heard of any Earth sized exoplanets within 10, or 1000, LY.)
You could search for "Terestrial Planet Finder" to see how JPL would go a out this and see why even then they can't get this off the ground.