Monolithic interferometric modules for multi-axis coordinate positioning with sub-nanometre precision

We report on developing, characterizing, and verifying a compact, monolithic laser interferometric assembly designed for high-precision two- and three-axis displacement measurements in coordinate positioning systems. The design targets OEM integration into advanced precision motion platforms, including nanometrology instruments, semiconductor manufacturing equipment, and ultra-high vacuum (UHV) environments. Using a single laser source, the assembly integrates multiple interferometers into a monolithic L-shaped base frame, enabling sub-nanometer periodic error in X-Y motion systems while minimizing geometric and thermal instabilities. The pre-aligned and pre-adjusted architecture simplifies integration, enhances long-term stability, and ensures consistent metrological performance. The system's verification protocol employs quadrature phase analysis and systematic error metrics to characterize performance and optimise assembly. The results indicate sub-nanometer measurement capability and suggest the system's suitability for scalable implementation in advanced coordinate metrology applications.