Yeah, many of the theoretical solar sail ideas fall down on what I consider a useful "probe" is, and what it can mass. As mentioned in my other comment, if you define the "probe" to be "a single particle" we /already/ do this all the time in particle accelerators. But it's clearly not a useful "probe" I believe the original thought experiment implied. A few hundred grams of super thin solar sail material is still very much in the "Not A Probe" definition in my mind.

Plus even the best laser dispersion quickly gets significant at the distances required to give the sail the time to accelerate at such a low thrust.

Roundtrip Interstellar Travel Using Laser-Pushed Lightsails

https://ia800108.us.archive.org/view_archive.php?archive=/24...