The study of cold or obscured, red astrophysical sources can significantly benefit from adaptive optics (AO) systems employing infrared (IR) wavefront sensors. One particular area is the study of exoplanets around M-dwarf stars and planet formation within protoplanetary disks in star-forming regions. Such objects are faint at visible wavelengths but bright enough in the IR to be used as a natural guide star for the AO system. Doing the wavefront sensing at IR wavelengths enables high-resolution AO correction for such science cases, with the potential to reach the contrasts required for direct imaging of exoplanets. To this end, a new near-infrared pyramid wavefront sensor (PyWFS) has been added to the Keck II AO system, extending the performance of the facility AO system for the study of faint red objects. We present the Keck II PyWFS, which represents a number of firsts, including the first PyWFS installed on a segmented telescope and the first use of an IR PyWFS on a 10-m class telescope. We discuss the scientific and technological advantages offered by IR wavefront sensing and present the design and commissioning of the Keck PyWFS. In particular, we report on the performance of the Selex Avalanche Photodiode for HgCdTe InfraRed Array detector used for the PyWFS and highlight the novelty of this wavefront sensor in terms of the performance for faint red objects and the improvement in contrast. The system has been commissioned for science with the vortex coronagraph in the NIRC2 IR science instrument and is being commissioned alongside a new fiber injection unit for NIRSPEC. We present the first science verification of the system—to facilitate the study of exoplanets around M-type stars.

中文翻译：

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凯克配有红外金字塔波前传感器的自适应光学元件

寒冷或模糊的红色天文学资源的研究可从采用红外（IR）波前传感器的自适应光学（AO）系统中受益匪浅。一个特殊的领域是研究M型矮星周围的系外行星和恒星形成区原行星盘内行星的形成。这些物体在可见光波长下微弱，但是在红外光下足够明亮，可以用作AO系统的自然导星。在红外波长下进行波前感测可以对此类科学案例进行高分辨率的AO校正，并有可能达到对系外行星进行直接成像所需的对比度。为此，在Keck II AO系统中增加了新的近红外金字塔波前传感器（PyWFS），从而扩展了用于研究微弱红色物体的AO系统的性能。我们介绍了Keck II PyWFS，这代表了许多首创，包括安装在分段望远镜上的第一台PyWFS以及在10米级望远镜上首次使用的IR PyWFS。我们讨论了红外波前感测技术的科学和技术优势，并介绍了Keck PyWFS的设计和调试。特别是，我们报告了用于PyWFS的HgCdTe红外阵列检测器用Selex雪崩光电二极管的性能，并就微弱红色物体的性能和对比度的改善突出了这种波前传感器的新颖性。该系统已通过NIRC2红外科学仪器中的涡旋冠冕仪进行了科学调试，并且正在与用于NIRSPEC的新型光纤注入装置一起进行调试。