Single-layer metasurface enables a compact rotational speed detection system.

Area of Science:

• Optics and Photonics
• Metrology
• Applied Physics

Background:

• Rotational Doppler effect (RDE) detection offers rapid, non-contact measurement of rotational speed.
• Existing RDE systems often employ bulky optical components like spatial light modulators (SLMs) or digital micromirror devices (DMDs), hindering miniaturization and integration.
• The complexity of current RDE systems limits their practical application in space-constrained environments.

Purpose of the Study:

• To propose and demonstrate a novel, compact method for rotational speed detection based on RDE.
• To overcome the limitations of bulky optical elements in conventional RDE systems.
• To enable the development of miniature and integrated RDE-based metrology devices.

Main Methods:

• Generation of conjugate topological vortex beams using a single-layer metasurface.
• Implementation of a compact RDE-based rotational speed detection system.
• Analysis of frequency peak gaps in echo light signals for speed determination.

Main Results:

• Successful demonstration of the first compact RDE-based rotational speed detection system.
• Accurate measurement of rotational speed by analyzing frequency peak gaps.
• Achieved a maximum average relative measurement error of 0.812%.

Conclusions:

• The proposed single-layer metasurface method significantly simplifies RDE system design.
• This advancement paves the way for miniature, integrated RDE metrology devices.
• The technology is well-suited for applications with stringent size and payload limitations.