Robust Laser Beam Tracking Control using Micro/Nano Dual-Stage Manipulators

International audienceThis paper presents a study of the control problem of a laser beam illuminating and focusing a microobject subjected to dynamic disturbances using light intensity for feedback only. The main idea is to guide and track the beam with a hybrid micro/nanomanipulator which is driven by a control signal generated by processing the beam intensity sensed by a four-quadrant photodiode. Since the pointing location of the beam depends on real-time control issues related to temperature variation, vibrations, output intensity control, and collimation of the light output, the 2-D beam location to the photodiode sensor measurement output is estimated in real-time. We use the Kalman filter (KF) algorithm for estimating the state of the linear system necessary for implementing the proposed track-following control approach. To do so a robust master/slave control strategy for dual-stage micro/nanomanipulator is presented based on sensitivity function decoupling design methodology. The decoupled feedback controller is synthesized and implemented in a 6 dof micro/nanomanipulator capable of nanometer resolution through several hundreds micrometer range. A case study relevant to tracking a laser-beam for imaging purposes is presented

Robust Laser Beam Tracking Control using Micro/Nano Dual-Stage Manipulators

Abstract — This paper presents a study of the control problem of a laser beam illuminating and focusing a microobject subjected to dynamic disturbances using light intensity for feedback only. The main idea is to guide and track the beam with a hybrid micro/nanomanipulator which is driven by a control signal generated by processing the beam intensity sensed by a four-quadrant photodiode. Since the pointing location of the beam depends on real-time control issues related to temperature variation, vibrations, output intensity control, and collimation of the light output, the 2-D beam location to the photodiode sensor measurement output is estimated in real-time. We use the Kalman filter (KF) algorithm for estimating the state of the linear system necessary for implementing the proposed track-following control approach. To do so a robust master/slave control strategy for dual-stage micro/nanomanipulator is presented based on sensitivity function decoupling design methodology. The decoupled feedback controller is synthesized and implemented in a 6 dof micro/nanomanipulator capable of nanometer resolution through several hundreds micrometer range. A case study relevant to tracking a laser-beam for imaging purposes is presented. I