Implementation of modal optimization system of Subaru-188 adaptive optics

Abstract

Subaru AO-188 is a curvature adaptive optics system with 188 elements. It has been developed by NAOJ (National Astronomical Observatory of Japan) in recent years, as the up grade from the existing 36-element AO system currently in operation at Subaru telescope. In this upgrade, the control scheme is also changed from zonal control to modal control. This paper presents development and implementation of the modal optimization system for this new AO-188. Also, we will introduce some special features and attempt in our implementation, such as consideration of resonance of deformable mirror at the lower order modes, and extension of the scheme for the optimization of the magnitude of membrane mirror in wave front sensor. Those are simple but shall be useful enhancement for the better performance to the conservative configuration with conventional modal control, and possibly useful in other extended operation modes or control schemes recently in research and development as well.

Recent development in real time control system of Subaru LGSAO-188

“…The current on-going work in real-time control system of Subaru LGS AO is incorporation of DHS (data handling system), the main part of which has been previously implemented already [1]. The DHS is built on a computer independent from RTS (real time control system), and would be connected to RTS over the network and provided with the streaming data of DM voltage and WFS signals in real-time.…”

“…The major item is to invoke the optimum gain control, which is being implemented on the data handling system and attached to the real time control system. The function of the automatic gain control is as already mentioned in our previous SPIE paper [1], by calculating temporal spectrum of the deformable mirror and the curvature sensing, optimum feed back gain [2][3][4][5] is calculated and adjusted continuously. This is expected to enhance the performance during the long time exposure where the condition of turbulence is changing.…”