The first scientific observations with adaptive optics (AO) at W. M. Keck Observatory (WMKO) began in 1999. Through 2023, over 1200 refereed science papers have been published using data from the WMKO AO systems. The scientific competitiveness of AO at WMKO has been maintained through a continuous series of AO and instrument upgrades and additions. This tradition continues with AO being a centerpiece of WMKO’s scientific strategic plan for 2035. We will provide an overview of the current and planned AO projects from the context of this strategic plan. The current projects include implementation of new real-time controllers, the KAPA laser tomography system and the HAKA high-order deformable mirror system, the development of multiple advanced wavefront sensing and control techniques, the ORCAS space-based guide star project, and three new AO science instruments. We will also summarize steps toward the future strategic directions which are centered on ground-layer, visible and high-contrast AO.
The Real Time Controllers (RTCs) for the W. M. Keck Observatory Adaptive Optics (AO) systems have been upgraded from a Field Programmable Gate Array (FPGA) to a Graphics Processing Unit (GPU) based solution. The previous RTCs, operating since 2007, had reached their limitations after upgrades to support new hardware including an Infra-Red (IR) Tip/Tilt (TT) Wave Front Sensor (WFS) on Keck I and a Pyramid WFS on Keck II. The new RTC, fabricated by a Microgate-led consortium with SUT leading the computation engine development, provides a flexible platform that improves processing bandwidth and allows for easier integration with new hardware and control algorithms. Along with the new GPU-based RTC, the upgrade includes a new hardware Interface Module (IM), new OCAM2K EMCCD cameras, and a new Telemetry Recording Server (TRS). The first system upgrade to take advantage of the new RTC is the Keck I All-sky Precision Adaptive Optics (KAPA) Laser Tomography AO (LTAO) system, which uses the larger and more sensitive OCAM2K EMCCD camera, tomographic reconstruction from four Laser Guide Stars (LGS), and improvements to the IR TT WFS. On Keck II the new RTC will enable a new higher-order Deformable Mirror (DM) as part of the HAKA (High order Advanced Keck Adaptive optics) project, which will also use an EMCCD camera. In the future, the new RTC will allow the possibility for new developments such as the proposed ‘IWA (Infrared Wavefront sensor Adaptive optics) system. The new RTC saw first light in 2021. The Keck I system was released for science observations in late 2023, with the Keck II system released for science in early 2024.
We report on two critical upgrades to NIRC2, the workhorse diffraction-limited infrared instrument in use with the Keck II telescope Adaptive Optics (AO) system at the W. M. Keck Observatory. NIRC2 has been in operation for over two decades and it is one of the most productive instruments at WMKO. The NIRC2 detector is a 1Kx1K InSb Aladdin-3. We have upgraded the detector electronics from the original system based on transputers to a state-of-the-art Archon controller. One of the most demanded NIRC2 observing modes is high-contrast imaging using Vector Vortex Coronagraphic (VVC) masks, which have been available to the NIRC2 observing community since 2015. To maximize the attenuation of the AO-generated Point Spread Function (PSF) core, the star needs to be precisely centered on the vortex mask over the course of an observation. This is achieved with a servo loop control software based on the Quadrant Analysis of Coronagraphic Images for Tip-tilt Sensing (QACITS) technique. We have migrated the original IDL-based QACITS software to Python, including several updates and a new graphical interface. Both Archon and QACITS upgrades are aimed at boosting the NIRC2 observing efficiency.
Maintaining the co-phasing of the primary mirror segments is a critical aspect to the operation of segmented telescopes. However, speckle-based measurements of the phasing of the Keck primary estimated static aberrations of approximately 90 nm rms that are not sensed by the current edge-sensing segment control system. We propose directly sensing and controlling the primary via the wavefront sensor of the adaptive optics system, as a Controllable Segmented Primary (CSP), to actively correct its phasing. In this work, we consider strategies for implementing and calibrating the CSP system on-sky.
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