Closed-Loop Positioning with Interferometric Precision

The application note highlights the capability of the PICOSCALE Interferometer to enable closed-loop positioning of samples with picometer precision. By integrating the interferometer with SmarAct's modular control system (MCS2), the setup achieves precise, low-latency control of a translation stage, addressing challenges in high-precision manufacturing and research.

Problem: Conventional positioning systems rely on integrated position feedback that often measures far from the point of interest (POI). This can lead to unaccounted drifts, compromising the desired precision and accuracy for advanced applications.

Solution: The PICOSCALE Interferometer directly measures displacement at or near the POI, providing unparalleled resolution and accuracy. By coupling the interferometer with SmarAct's MCS2 control system, real-time feedback loops are established, ensuring high-precision control with minimal latency.

Implementation

• The setup includes:
  • A target mirror mounted on a cantilever and aligned with a PICOSCALE sensor head.
  • The sensor head collects displacement data using interferometric methods and transmits it to the PICOSCALE controller.
  • The controller processes the data and sends it to the MCS2 via the SmarAct SI interface.
  • The MCS2 drives a SmarAct SLC1730 translation stage based on the feedback signal, achieving closed-loop control with latencies below 100 µs.

Result: The system successfully demonstrates precise closed-loop positioning, maintaining nanometer-level accuracy and low-latency feedback. Differential measurement setups further enhance performance by mitigating environmental disturbances, achieving highly accurate and stable positioning even in demanding conditions.