The Focal Plane Systems (FPS) were designed to replace the traditional SDSS fiber plug-plate systems at the Sloan and du Pont telescopes for the 5th generation Sloan Digital Sky Survey (SDSS-V).  The first FPS was deployed on the 2.4m Sloan Telescope at Apache Point Observatory in November 2021, and the second was deployed on the 2.4m Du Pont Telescope at Las Campanas Observatory in August 2022.

Each FPS deploys 500 zonal fiber positioners that allow us to reconfigure the fibers onto a new target field within 2-3 minutes of acquisition. Each positioner carries three fibers: two science fibers that feed the BOSS and APOGEE spectrographs and a third back-illuminated metrology fiber is used in conjunction with a telescope-mounted Fiber Viewing Camera (FVC) to measure the absolute positions of the fiber heads. The 300 APOGEE fibers are distributed among the 500 positioners to maximize common field coverage. A set of fiber-illuminated fiducials distributed in and around the positioner array establish a fixed reference frame for the FVC system. Finally, six CCD cameras mounted around the periphery of the focal plane provide acquisition, guiding, and focus monitoring functions. The FPS is the key enabling technology of the SDSS-V Milky Way and Black Hole Mapper surveys.