Sigfit Software - Adaptive Control

Adaptive Control Simulation

Unwanted optical surface disturbances could be supplied by a finite element analysis or generated by SigFit.

Each actuator influence function is the surface deformation resulting from a unit input to a single actuator and is obtained from the results of a finite element analysis or generated by SigFit.

SigFit computes the best corrected surface prediction by computing the actuator inputs which result in minimizing the surface RMS error

SigFit’s adaptive control simulation allows the user to predict the best corrected surface of an adaptive optic. The surface deformation descriptions to be corrected are input in the same manner as is done for a polynomial fitting analysis. Additional inputs require the specification of a result file containing the actuator influence data sets.

These data sets consist of finite element subcases each representing the effect of one actuator. Augment actuator cases which are generated internal to SigFit may also be selected. Augment actuator cases are commonly used to remove the best fit plane and/or power to simulate focus correction or the inability of a metrology test to see such deformations.

The predicted corrected surface may be fit with polynomials, sent to an optical analysis input file, interpolated to an array, or viewed in a post-processor with nodal result files. The following table shows an example of the printed summary output for adaptive control analysis. The table shows the input surface (disturbance to be corrected), the input surface minus its best-fit-plane motion, and the corrected surface expressed as RMS error.

Table 1

Additional printed output includes the inputs to each actuator and the polynomial fit to the corrected surface. Other output methods such as array interpolation or optical analysis import files may be generated as well.