an angle of rotation of the mirror may be related to an applied voltage as follows v x0 the sensor offset for the x axis when the angle of rotation is 0 degrees v y0 the sensor offset for the y axis when the angle of rotation is 0 degrees u03b1 the sensor gain for the x axis u03b2 the sensor gain for the y axis where v x is the x axis sensor voltage and v y the y axis sensor voltage the following equations apply here u03b8 and u03c6 are the angles of rotation with respect to the x and y axes of the mirror respectively the equations 1 and 2 assume that a response is linear with respect to the angle of rotation and there is no dependence on the angle of rotation with respect to the other axis the v yo and v x0 can be considered offset terms and u03b1 and u03b2 can be considered gain terms the equations 1 and 2 are easily modified to incorporate dependence between x and y axes of rotation as well as lower order terms as follows in operation it is desired that an input mirror 26 a align with an output mirror 26 b in order to accomplish this the mirror 26 a has to be turned with respect to the x axis and y axis given a desired angle a servo control for the mirrors uses the equations above to relate the sensor voltages to the desired angle from equation 1 it is clear that to solve for the unknowns v xo and u03b1 it is necessary to solve a system of two equations with two unknowns hence it.