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Misalignment Decoupling and Tilt-to-Length Suppression in a Micro-Actuated Beam Steering Mechanism via Nonlinear
Yang Li1,2, Changkang Fu1,2, Hongming Zhang1,2
1State Key Laboratory of Optical Field Manipulation Science and Technology, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China.
Micromachines
|May 27, 2026
Summary
A new nonlinear cyclic modulation method effectively identifies and suppresses tilt-to-length (TTL) coupling, a major noise source in precision interferometry. This technique significantly reduces noise, improving pointing accuracy and parasitic displacement in sensitive optical systems.
Area of Science:
- Physics
- Optical Engineering
- Metrology
Background:
- Tilt-to-length (TTL) coupling is a significant noise source in high-precision interferometric measurements.
- Angular actuation and beam steering systems are particularly susceptible to TTL noise.
Purpose of the Study:
- To propose and validate a nonlinear cyclic modulation method for identifying lateral misalignment.
- To suppress TTL coupling noise in precision interferometric systems.
Main Methods:
- Applying controlled sinusoidal angular excitation to the system.
- Evaluating the complex modulus ratio between optical path difference (OPD) and beam angle at modulation frequency.
- Separating and quantifying TTL noise in the frequency domain.
Main Results:
- Lateral offset correction reduced TTL noise by 94% (suppression factor of 15.5).
- Achieved pointing control better than 21 µm/rad.
- Reduced parasitic displacement noise of the point-ahead angle mechanism (PAAM) from 10 pm/Hz1/2 to below 4 pm/Hz1/2.
Conclusions:
- The proposed modulation-based framework effectively identifies and suppresses TTL coupling.
- The method is applicable to various precision interferometric systems requiring high accuracy.
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