Measurement Range Enhancement of a Scanning Probe by the Real Time Adjustment of the Interferometer Reference Mirror

Scanning probes on the micro/nano-coordinate measuring machines (micro/nano-CMMs) can produce on/off signals and achieve 3D measurement ability within a specific range. The authors have developed several scanning probes based on a 2D angle sensor and a miniature Michelson interferometer that can work within ± 10~\mu \text{m} . When the probe's lateral displacement is greater than 10~\mu \text{m} , the interferometer signal is easy to break, limiting the measurement range of these probes. A 2D angle fine-tuning stage using piezoelectric stack actuators is designed to adjust the reference mirror in real-time to solve signal separation between the reference beam and the measuring beam of the miniature Michelson interferometer. The coupling of the 2D angle fine-tuning stage in the x and y directions is analyzed, and the coupling model is established for a relatively precise compensation. Experimental results show that through the proposed 2D angle fine-tuning stage, the measurement range of the probe can be extended to ± 30~\mu \text{m} , and the interference signal can still remain stable and uninterrupted.