All-optical compensation strategy for high-sensitive and precise rotating velocimetry of a multi-pose target

Rotational Doppler velocimetry holds immense potential for practical applications. However, the sensitivity and precision of existing systems are restricted by the broadening of rotational Doppler spectrum caused by the varied postures of a rotating target surface. Herein, we present and attest to an all-optical compensation scheme for the first time capable of overcoming this restriction, based upon the optical rotational Doppler effect and the eigenmode superposition and decomposition principle. It relies on the iterative compensations of broadening intramode phase differences between aligned and misaligned surfaces into the orbital-angular-momentum phase spectrum of emitted light field, correspondingly. In contrast to uncompensated situations, our demonstrated system can not only achieve the considerable improvement of signal-to-noise ratio up to roughly 2∼6 orders of magnitude and reduce the relative error below 1.5% under a certain offsets and rotating velocity range, which thus highlights the establishment of a high-sensitive and precise pathway for rotating velocimetry of a multi-pose target. The validated approach and findings may be applied in various real-world spinning scenarios, such as astronomical observations, industrial manufacturing and in-vivo biomedical engineering.