Ralph, TarquinAltin, PaulRabeling, DavidMcClelland, DavidShaddock, Daniel2021-07-131559-128Xhttp://hdl.handle.net/1885/240556We present a new technique for the fine alignment sensing of optical interferometers. Unlike conventional wavefront sensing systems, which use multielement photodiodes, this approach works with a single-element photodiode, in combination with a spatial light modulator (SLM) and digitally enhanced heterodyne interferometry. As all signals pass through a single photodetection and analog path, the technique exhibits high common-mode rejection to low frequency errors present in conventional systems. By changing the modulation pattern on the SLM, the technique can also be extended to sensing higher-order wavefront errors. In this paper, we demonstrate the technique experimentally and compare performance with a conventional heterodyne wavefront sensing system. This may improve and simplify alignment systems in space-based interferometers such as the planned LISA gravitational wave detector and provide a way to optimize the power in laser cavities not possible with the traditional segmented diode approachAustralian National University (ANU).application/pdfen-AU© 2017 Optical Society of America201710.1364/AO.56.0023532020-11-23