From Halopedia, the Halo wiki
Project THEIA is a UNSC research project focusing on the production of optical sensors. The project is a field test for - among other things - extremely compact, mission-specific optronics used by field commanders. A number of FCI-I attachments employ THEIA technology, including the FCI-I/BASIL attachment for the GEN3 SOLDIER-class Mjolnir and the FCI-I/PROFORMA attachment for the ENIGMA-class Mjolnir - the latter of which being one of many THEIA-derived generation-after-next sensor systems. THEIA-derived technology is also present in the MAUROS faceplate upgrade for the Mark V Zeta helmet.
List of appearances