The calibration and verification equipment (CAVE) for KASM

The Keck Adaptive Secondary Mirror (KASM) project will broaden the use of adaptive optics on the Keck I telescope by integrating the correction device into the secondary mirror. By replacing the static secondary with a high-actuator count convex deformable mirror, image sharpening will be available to all instrument ports. The KASM optical surface will be a thin shell polished to match the optical prescription of the existing Keck I secondary mirror to within a few microns. The final correction of the optical shape will be achieved with control of the ASM’s actuators. The calibration and verification equipment (CAVE) will be an optical metrology package designed to verify that the delivered KASM has the correct optical figure. CAVE will also be used to verify and calibrate the actuator motion, both spatially and temporally, forming the basis for the actuator influence functions used in closed-loop operations. CAVE will be used during testing at the University of California Observatories optical laboratory, as well as during commissioning and periodic verification at the W.M. Keck Observatory, necessitating a robust and repeatable kinematic mounting arrangement. We describe the design of CAVE and develop a concept for laboratory and telescope facility operations and calibration.