A microdisplay is a display that has a small size and a high resolution. It is usually on the scale of one inch wide. It is usually flat and built on technology like LCOS or OLED.
Microdisplays exist because of the need for electronic viewfinders in cameras.[1]
See also List of microdisplay companies
The resolution of microdisplays is often very high. A microdisplay can be used as the display source in a microlens-based light field display of a small size.
Companies that provide microdisplays included eMagin, bought by Samsung.