Daylight redirecting film

Refraction and total internal reflection inside optical prisms can bend beams of light.

Daylight redirecting film is made of acrylic[5] on a flexible polyester backing, one side coated with a pressure-sensitive adhesive (to make it peel-and-stick).

Some film is moulded with tiny triangular prisms, making a flexible peel-and-stick miniature prismatic panel.

Another film is moulded with thin near-horizontal voids protruding into or through the acrylic; the slits reflect light hitting their top surfaces upwards.

[2] The slit-based films are more transparent (both are translucent), but when the sun is high, they tend to send the light up at the ceiling, not deeper into the room.