pinhole
A very small hole, such as one made by a needle or a tiny opening in a surface.
紙に針穴を開ける。
I make a pinhole in the paper.
針穴から光が漏れている。
Light is leaking through the pinhole.
Compound of 針 (hari, 'needle') and 穴 (ana, 'hole'). The reading はりあな is a straightforward combination.