Just adding information I finding, This stuff ain't cheap...
MAKROLON® OP Clear & TUFFAK® Optical Grade High-Impact Polycarbonate Sheet
Polycarbonate sheet has all the properties and features you demand, including:
Virtually unbreakable with 250 times the impact strength of float glass and 30 times that of acrylic.
High optical clarity
Highest light transmission
UV stability
Low distortion