Overview and operation of the DESI focal plane

Abstract

The Dark Energy Spectroscopic Instrument (DESI) is undertaking an ambitious spectroscopic survey of 35 million galaxies and quasars in its 5 year program. With this data, DESI will explore cosmic history through Baryon Acoustic Oscillations and will measure the growth of large scale structure with Redshift Space Distortions. To do this, DESI was constructed with a robotic focal plane system containing 5,020 fiber positioner robots, each equipped with a single fiber, enabling the collection of 5,000 simultaneous spectra. These positioner robots nominally have a 6mm patrol radius and a minimum pitch of 10.4mm such that neighboring robots have overlapping patrol regions. This presentation will give an overview of the focal plane system and its operation. We will begin by introducing its structure and key components. We will also discuss how the focal plane and its robots operate, detailing how the robots are positioned to targets. This will include an introduction to the software model for DESI fiber positioner robots, an overview of the anti-collision algorithm used to prevent collisions between neighboring robots and safety measures employed during operation.