Two-degrees-of-freedom piezo-driven fast steering mirror with cross-axis decoupling capability

Area of Science:

• Optics and Photonics
• Mechanical Engineering
• Control Systems

Background:

• Piezo-driven fast steering mirrors (PFSMs) are crucial for high-precision optical systems.
• Mechanical cross-coupling between axes degrades the scanning precision of traditional PFSMs.
• Achieving independent two-degrees-of-freedom (2-DoF) motion is a significant challenge.

Purpose of the Study:

• To propose and validate a novel 2-DoF PFSM with inherent cross-axis decoupling capability.
• To analytically model the static and dynamic characteristics of the proposed PFSM.
• To demonstrate the effectiveness of the decoupling mechanism through experimental trajectory tracking.

Main Methods:

• Design and fabrication of a 2-DoF PFSM utilizing 2-DoF flexure hinges for decoupling.
• Analytical modeling of the PFSM's static and dynamic behavior.
• Implementation of independent proportional-integral-derivative (PID) controllers for each degree of freedom.
• Experimental validation using 1-DoF and 2-DoF trajectory tracking tests.

Main Results:

• The proposed PFSM achieves a tilt range of ±7 mrad for both axes.
• Low dynamic cross-coupling ratios below 2% (-34 dB) were experimentally verified.
• Bandwidths for both axes exceed 810 Hz.
• Maximal tracking errors are less than 0.2% for 1-DoF and 1% for 2-DoF trajectories.

Conclusions:

• The developed 2-DoF PFSM effectively mitigates cross-axis coupling, enhancing scanning precision.
• The analytical models and control strategy provide a robust framework for PFSM design.
• The experimental results confirm the high performance and potential applications of the decoupled PFSM.