It's a neat idea but I wouldn't say "three mirrors, each measuring 17 sq m" is particularly "giant".
In English there isn't a general word for altering a trajectory into an object. In this case however, reflect is precisely suited to what mirrors do to light and doesn't have the confusing inverse connotation of away. You reflect away from something or onto something equally well in English.
Divert.
yay for the elegance of latin-based prefixes! =)
In a neat coincidence "umbrage" and "umbrella" apparently share a common origin in Latin "umbra" (shade).