Description
Exoplanet imaging requires extremely high AO performance over a small field of view to achieve the required contrast. The next generation of high contrast instruments, such as the Planet Camera and Spectrograph (PCS) for the ELT, will put even greater demands on AO performance. The Pyramid Wavefront Sensor (PWFS) (Ragazzoni, 1996) is widely recognised as providing the best closed-loop performance for high contrast single conjugate adaptive optics (AO) systems, with many current and future AO systems selecting the PWFS as their primary natural guide star wavefront sensor. Here we propose combining the PWFS with a microwave kinetic inductance detector (MKID) (Day et al., 2003) array and describe the benefits this can bring to future AO system performance.
An MKID array is a superconducting detector with unique properties compared to CCD/CMOS detectors that provide a measure of the position, arrival time and energy of each photon incident on the array. Sorting the photons into wavebands allows us to measure the wavefront at multiple wavelengths simultaneously, providing additional information to increase the performance of the AO system and collecting a large number of photons across a wide wavelength band. First, we will introduce the MKID and PWFS, and present the concept of a chromatic PWFS. We will present the advantages of using this concept, demonstrating increased contrast and limiting magnitude compared to a single-band PWFS. Finally, we will present simulation results in an ELT environment, demonstrating the features which make this concept a good candidate for the future PCS XAO system.
