Study On The Detection Of Rotating Object Based On Optical Vortices’ Rotational Doppler Shift

Optical vortices are a new kind of structure fields with helical wavefront and doughnut structure.Such unique characteristics contribute to their widely applications in lots of domains,for instance,optical communications,rotation detection,optical tweezers,quantum entanglement,etc.This paper mainly focuses on the rotational Doppler shift of optical vortices,and their applications in rotation detection.Three main points as follows are discussed in this paper.1.The most common optical vortices,including Laguerre-Gauss beams,Bessel-Gauss beams,perfect vortices,polarization vortices,vectorial vortex beams,and the way to generate them,are demonstrated.Moreover,tunable production of polarization vortices with arbitrary polarization topological charge through a Sagnac-like interferometer is also proposed.2.Principles of rotational Doppler shift,and how to detect a ration object,are discussed in detail.3.The two-fold multiplexed Laguerre-Gauss and Bessel-Gauss beams with opposite topological charges,are employed as the source,to illuminate the rotating object directly.A photodiode is used to capture scatter lights.After analyzing the intensity-modulation of such scatter lights,an apparent frequency shift is observed,which can reveal the angular velocity.The favorable experiment results indicate that,the detection accuracy can be improved,through increasing the sample interval or the absolute value of topological charges.Additionally,obstruction-free rotation detection can be realized by employing Bessel-Gauss beams as the source.