The LWBI includes an optical head, containing an interferometer, detectors, translation mechanism, and metrology laser, using light weight technologies and a more mass-conscious approach. The lightweight balloon interferometer (LWBI) will have a performance similar to that of the JPL MkIV, yet will weigh just one fifth of the mass. The reduced payload size and mass will make the LWBI much easier to launch, facilitating close co-location with observations from space-borne sensors such as TES and HIRDLS on board AURA.