yafaray does this with ease its time cycles finish this once and for all
dispersion included for cycles study
Please post constructive feedback / suggestions, not just some caustics images.
Detailed caustics require intensive calculations and are only necessary in specific scenes, such as close-ups of tableware or jewelry. Cycles is targeted at speedy animation rendering, hence detailed caustics have no priority so far.
Indeed, there is a way.
Those are fake caustics and can be implemented as a shadow map almost for free even in Eevee:
As for real caustics there’s a Metropolis. It is not ideal either, but probably can be implemented in Cycles (though its not that easy)
Yahweh the true God is the only creator of real anything else is imitation and fake but cycles is long overdue for proper physics light caustics rather than cheap light shadow ray hacks and no one can argue with this.
OK, I think enough caustics-themed images have been posted. I’m closing this thread.
Concrete proposals to improve Cycles caustics are welcome in the User Feedback section, or if you’re a developer interested in contributing to Blender, post your proposal in the Cycles Development section.