From Star Trek: Theurgy Wiki
The aluminium surface wafer was chemically bond onto a triaxial optical display crystal membrane, which served as a high resolution graphic display medium. Monocrystal microwaveguides at 1. 8 mm intervals provided electro plasma system power transmission to the upper sensor matrix and transducer layers.
The substrate of the controlled surface was composed of microfoamed polyduranide sheeting, which provided structural integrity to the assembly. Incorporated into this layer was a matrix of optical nanoprocessors that permitted the display surface sheeting to be self-configuring, once addressed and initialized by the local processor node. For redundancy's sake, the panel nanoprocessors included sufficient nonvolatile memory to permit system operation, even in the absence of main computer support.
Image and text from the Starfleet Technical Manual.