bamboo screen
笭 centers on a screen or lattice made from bamboo, used to partition space or filter light.
笭 combines 竹 (bamboo) with 令, which likely contributes a phonetic element. The character refers to a bamboo screen or lattice, consistent with the bamboo radical.
The bamboo crown 竹 sits above 令, like a woven bamboo screen filtering light. Picture a delicate bamboo lattice used as a room divider.
For レイ, imagine a ray of light passing through the bamboo screen: ray -> レイ, and the screen filters the light into soft patterns.