Photonic integrated circuit heterodyne interferometer laser gauges for picometer-class metrology

The Habitable Worlds Observatory (HWO) has the ambitious goal of directly imaging and characterizing Exo-earths in search of life in the universe. For HWO to achieve this, the observatory requires a robust wavefront control system (WCS) to maintain wavefront stability to roughly 2 pm over up to 1000 seconds. As part of the larger WCS, HWO will employ a laser metrology truss consisting of many laser metrology gauges to measure the relative pose between the primary mirror segments and the secondary mirror. Lockheed Martin has developed laser metrology gauges with pm-class stability using photonic integrated circuit (PICs) heterodyne interferometers. In this presentation, we report experimental measurements of metrology errors internal to our PIC gauges. We also present an architecture study on placement and orientation of metrology gauges to minimize wavefront error. Additionally, we present a technology readiness level assessment and roadmap for achieving a level 5 for the gauges.