From the spline approximation method using normalized parabolic B-splines there have been obtained analytical expressions for the mean square aperture error of the phase front regeneration taking into account the measurement noise of the Hartman type phase front sensor. There have been evaluated the correlation matrix of the control signal vector of the adaptive flexible reflector for the turbulence Kolmogorov spectrum. On the basis of the obtained result there have been written the expression for the optimal recurrent evaluation of the control signal vector of the piezoceramie plate-based adaptive flexible reflector.