Digital Micromirror Devices (DMD) were invented by Texas Instruments in 1987 and are the core of the DLP technology used for video projection.
In the on state, light from the projector bulb is reflected into the lens making the pixel appear bright on the screen.
One future application is controlling the light in buildings, based on micromirrors between the two panes of Insulated glazing.
[1] A MEMS scanning micromirror consists of a silicon device with a millimeter-scale mirror at the center.
The mirror is typically connected to flexures that allow it to oscillate on a single axis or biaxially, to project or capture light.