The Laser Interferometry Space Antenna (LISA) is the third Large Mission of ESA's Cosmic Vision program and from 2034 on will measure gravitational waves (GWs) with a wavelength roughly one million times longer than ground-based GW detectors like Virgo and LIGO. To measure the interference patterns of the 1 micron laser beams, large low-noise quadrant photodiodes (QPDs) are needed that are not available on the commercial market. In collaboration with Nikhef and Dutch photonics industry, SRON is developing such QPDs since 2018. Currently, this project is in phase A (feasibility study).