Optimum deformable mirror modes for sensorless adaptive optics

Wavefront sensorless adaptive optics schemes rely upon the accurate generation of aberration modes by the adaptive element, usually a deformable mirror. Analytic functions are often used for representation of the aberrations in these systems. Such functions cannot be perfectly reproduced by deformable mirrors and the approximation errors can affect the aberration correction procedure. We derive alternative modal basis sets directly from the actuator influence functions, thus avoiding the approximation errors. We investigate how the choice of aberration modes affects the performance of a sensorless adaptive imaging system. The new modes are found to be most advantageous for deformable mirrors with a small number of actuators.