Theory and simulation of viscous damped reflection phase gratings

Micromachined reflection phase gratings operate via the electrostatic deflection of reflective microbeams. We develop a lumped parameter model for predicting the transient motion of these microbeams, taking into account electrostatic and tensile forces and viscous air damping via squeeze-film theory. We use this model to determine the time required for a deflected microbeam to return to its undeflected state. Our analysis shows that this re-set time is approximately one order of magnitude greater than the activation time.