In a major advance for high-precision metrology, researchers in South Korea have developed an “absolute distance measurement” system that comes remarkably close to the quantum limit of precision—measuring just 0.34 nanometers in only 25 microseconds.
The system, created by the Korea Research Institute of Standards and Science (KRISS), blends the best of two worlds: the precision of national length standards and the practicality of field-deployable devices.
Precision Meets Portability
Traditional length measurement tools, like single-wavelength laser interferometers, are precise but slow and spatially limited. They require complex setups and multiple stitched measurements to cover long distances. On the other hand, absolute distance systems can cover longer ranges in a single shot but typically sacrifice precision, landing in the micrometer range at best.
The KRISS team solved this trade-off by harnessing a powerful optical frequency comb (OFC). An OFC is a laser-based light source with thousands of evenly spaced frequencies—much like the keys on a piano—that offer both broad bandwidth and ultra-fine resolution. When used in spectral interferometry, this allows for both high-speed and high-accuracy measurements, even over longer distances.
Key Innovations
- Achieved sub-nanometer precision: 0.34 nm in 25 µs
- Measurement sensitivity near the quantum limit: 4.5·10⁻¹² m/Hz¹ᐟ²
- Compact and rugged design suitable for industrial field use
- Demonstrated remote sound sensing via acoustic vibrations
Implications for Industry and Science
“This achievement marks a significant step for Korea toward becoming a leading country in establishing next-generation length standards,” said Dr. Jang Yoon-Soo, senior researcher at KRISS. “The competitiveness of future industries such as AI semiconductors and quantum technologies hinges on the ability to accurately measure and control distances at the nanometer scale.”
The potential applications span from advanced manufacturing and robotics to quantum computing and aerospace engineering. The system’s rapid response and extraordinary resolution make it a candidate for replacing conventional tools in sectors where accuracy and speed are paramount.
A New Benchmark for Precision
The KRISS device doesn’t just break records—it raises the bar. With its compact form and ultra-fast measurements, the system could redefine what’s possible in length metrology. Next steps include refining its uncertainty model and integrating the technology into broader industrial platforms.
This research was supported by KRISS’s Basic Research Program and published in Laser & Photonics Reviews, a leading journal in optical science.
Journal: Laser & Photonics Reviews