A pinhead mirror can be used to create a camera similar to a pinhole camera

Pinhole camera

A pinhole camera is a simple camera without a lens and with a single small aperture – effectively a light-proof box with a small hole in one side. Light from a scene passes through this single point and projects an inverted image on the opposite side of the box...

. Instead of passing through a tiny hole, the light to form the image is reflected by a small disc-shaped mirror (with a diameter the same as that of a pinhole; about 0.15mm-0.4mm). One advantage is that a pinhead mirror can be swivelled to scan a scene or project a scene to different locations.

Pinhead mirror technology was protected under US patent 4,948,211 - "Method and Apparatus for Optical Imaging Using a Small, Flat Reflecting Surface" until the patent expired in 2009.