Abstract
An experimental optical bench test-bed for developing new wavefront sensing concepts for Multi-Conjugate Adaptive Optics (MCAO) systems is described. The main objective is to resolve imaging problems associated with wavefront sensing of the atmospheric turbulence for future MCAO systems on Extremely Large Telescopes (ELTs). The test-bed incorporates five reference sources, two deformable mirrors (DMs) and atmospheric phase screens to simulate a scaled version of a 10-m adaptive telescope operating at the K band. A recently proposed compact tomographic wavefront sensor is employed for star-oriented DMs control in the MCAO system. The MCAO test-bed is used to verify the feasibility of the wavefront sensing concept utilizing a field lenslet array for multi-pupil imaging on a single detector. First experimental results of MCAO correction with the proposed tomographic wavefront sensor are presented and compared to the theoretical prediction based on the characteristics of the phase screens, actuator density of the DMs and the guide star configuration.
Highlights
A laboratory setup of Multi-Conjugate Adaptive Optics (MCAO) system [1] has been built on an optical bench as a test-bed for developing new wavefront sensing concepts [2, 3]
An effective operation of the MCAO system at any position on the sky requires a number of artificial sources, namely laser guide stars (LGSs), and a wavefront sensing system for adequate probing of the atmospheric turbulence above the telescope
The virtual wavefront sensor comprises two sensors, here we present only the optical design for the primary WFS working as a multi-directional WFS [3] on the laboratory MCAO test-bed
Summary
A laboratory setup of Multi-Conjugate Adaptive Optics (MCAO) system [1] has been built on an optical bench as a test-bed for developing new wavefront sensing concepts [2, 3]. Due to intrinsic telescope aberrations associated with imaging of LGSs seen as objects at finite distance, the LGS wavefront propagation through the multi-mirror systems to the final telescope focus is hardly feasible To resolve this problem, one could design a special purpose telescope optical system optimized for imaging both laser and natural guide stars [7] or implement a virtual wavefront sensor (WFS) concept [2]. The virtual wavefront sensing concept employs a primary wavefront sensor (WFS) placed at the first available LGS focus where LGSs images are not significantly aberrated (which is true for typical two-mirror telescopes at Cassegrain or Gregorian focus), and a dedicated test WFS working in the telescope final focus The latter operates in conjunction with an artificial point source at an intermediate science telescope focus to monitor the effects of the second part of the telescope system containing additional DMs invisible for the primary WFS. It is our intention to develop and test the primary WFS system first before advancing to the level of complexity to verify the virtual WFS concept
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
