Design and practice multi-channel real time system on deformation control of optical plate

Optical plates (OP) play more and more important role in modern ground-based telescopes. They can be as segments composing primary mirror, deformable mirror for correcting air turbulence or active stressed lap used in polishing large aspherical optics. When control the deformation of these plates, we always confronts with common situations: high shape precision requirement, rapid deformation frequency with real time demand, intrinsic multi-channel coupling characteristic. So how to improve OP deformation performance becomes a critical task in practical design. In this paper, the control principle of OP is first introduced. Then a three-layer control architecture is presented. They are application layer, real time control layer and motion execution layer. After that we designed a prototype system following this framework, targeting active stressed polishing lap which has twelve motion channels. Both the hardware and software development are discussed thereafter. OP surface deformation experiments are carried out and surface shape obtained using LVDT array. Results verify the effectiveness of the design. And we are looking forward to use this control design in more channel and time demanding applications.