Researchers from the Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) of the Chinese Academy of Sciences developed a new grating interferometer design that significantly improves measurement stability under large three-dimensional angular misalignments. By introducing an extended Bias–Littrow configuration with angular self-compensation, the system overcomes a major limitation of conventional grating interferometers, which often fail when even small angular deviations occur. The study was published in Optics and Lasers in Engineering.

High-precision displacement measurement is essential in advanced manufacturing fields such as semiconductor fabrication, precision machining, and nanoscale assembly. Grating interferometers are widely valued for their compact structure, high resolution, and strong environmental resistance. However, in practical industrial environments, small tilts or rotational deviations of the measurement grating can easily disrupt beam alignment, degrade signal quality, and reduce measurement accuracy. This sensitivity has long restricted the broader use of grating interferometric systems in complex dynamic conditions.

To address this challenge, the research team designed a three-dimensional large-angular-tolerance grating interferometer (3DLAT-GI). The system incorporated an angular self-compensation unit into a bias–Littrow optical structure, allowing it to automatically suppress the effects of grating orientation errors across multiple axes. Through theoretical modeling, numerical simulation, and experimental validation, the researchers established how the new configuration maintained beam alignment even when the grating experienced significant angular variations.

A key innovation of the work was the use of corner-cube optical elements to preserve beam parallelism regardless of grating posture. This approach effectively prevented coherent beam separation, which is a major source of failure in traditional systems. The team also developed a mathematical threshold model to determine the practical angular tolerance limits of the system, providing a clear framework for future optimization and industrial deployment.

Experimental testing demonstrated that the interferometer maintained stable operation and nanometer-scale precision despite substantial simultaneous angular changes around multiple axes. Compared with conventional designs, the new system showed dramatically enhanced tolerance to rotational disturbances while preserving high measurement accuracy. This robustness makes the technology particularly suitable for demanding environments where vibration, alignment imperfections, or mechanical motion are unavoidable.

Beyond its immediate technical improvements, the study represents an important step forward for industrial metrology. Reliable displacement measurement under realistic working conditions is critical for improving manufacturing precision, reducing system downtime, and enabling next-generation technologies that require extreme positional control. Applications could extend from semiconductor lithography equipment to ultra-precision machine tools and advanced optical instrumentation.

This work provides a practical pathway toward more resilient and adaptable grating interferometric systems. By combining optical innovation with precision engineering, the new method expands the operational flexibility of displacement sensors and supports the growing demand for robust, high-accuracy measurement technologies in modern industry.