A new wavefront sensor for Keck: Pyramid wavefront sensing in the near infrared

A near infrared pyramid wavefront sensor (WFS) has been successfully installed on the Keck II telescope as part of the Keck Planet Imager and Characterizer (KPIC). The combination of the highly sensitive pyramid WFS and low noise infrared detector technology (specifically the SAPHIRA APD array) is opening up new opportunities for high resolution, high contrast imaging of faint red objects. Such capability will allow the detailed study of phenomena such as exoplanets around M-dwarf stars and planet formation in obscured star forming regions. This system is the first of its kind (an infrared pyramid WFS implemented on a 10 m class telescope), providing insight for future adaptive optics (AO) systems such as those planned for the Extremely Large Telescopes. In this paper we present an overview of this new wavefront sensor, including the results of commissioning and the science verification process. We explore the benefits of operating a pyramid WFS in the infrared and the new capabilities provided by such a system. In addition, we compare the current performance with that of Keck’s facility AO systems.

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