Design of a high-precision and non-contact dynamic angular displacement measurement with dual-Laser Doppler Vibrometers

Abstract

A wide dynamic range, high precision, non-contact and large bandwidth angular displacement measurement (ADM) is greatly necessary for the applications such as industrial control and military equipment. This paper proposes a simple and effective ADM method based on Doppler Effect, heterodyne detection and diffuse reflection, which can fulfill these requirements simultaneously. Two beams of parallel light generated by a pair of laser Doppler vibrometers are incident upon the surface of rotational target, then data processing unit acquires the velocity of dual laser incident points on the moving target, and resolves the rotational angular displacement and translation displacement of target through the relationship between dual laser beams dynamically. Several major measurement errors that may affect the ADM accuracy are analyzed. A high precision rotary table is used as an angular displacement standard to verify the measurement range and accuracy, the verification experiment shows that the measurement range is not less than ±10° and the measurement accuracy is 0.0362° based on the method. After using a polynomial error compensation, the measurement accuracy can be promoted to 0.0088°, and this compensation method can be applied to real time measurement.

High Sensitivity and Full-circle Optical Rotary Sensor for Non-cooperatively Tracing Wrist Tremor with Nanoradian Resolution

“…As to optical metrology, it has attracted increasing attention due to its nondestructive detection, tracking to the wavelength source and strong electromagnetic immunity. Normal interferometric methods need two beams or more to decouple the motions in multi-degree-of-freedom for the angle measurement [10], [11]. Some other optical methods can also measure the angle variation, including auto-collimatic method [12], total internal reflection method [13], grating-based interferometer [14], birefringence heterodyne interferometry [15], surface plasmon resonance [16], self-mixing interferometry [17], and dual-comb interferometry [18].…”

High Sensitivity and Full-circle Optical Rotary Sensor for Non-cooperatively Tracing Wrist Tremor with Nanoradian Resolution

“…As to optical metrology, it has attracted increasing attention due to its nondestructive detection, measuring traceability to the wavelength and strong electromagnetic immunity. Normal interferometric methods need two beams or more to decouple the motions in multi-degree-of-freedom for the angle measurement [10], [11]. Some other optical methods can also measure the angle variation, including auto-collimatic method [12], total internal reflection method [13], grating-based interferometer [14], birefringence heterodyne interferometry [15], surface plasmon resonance [16], self-mixing interferometry [17], and dual-comb interferometry [18].…”

Development of a High-Resolution All-Fiber Homodyne Laser Doppler Vibrometer

“…The influence of the internal parasitic reflections of the LDV is analyzed in Ref [ 25 ]. When measuring the rotational angular displacement with dual LDVs, Ref [ 26 ] improves the measurement accuracy to 0.0088° after analyzing the influence of the light intensity non-uniformity error, the systematic defect error, the synchronization error, and the sampling frequency-caused error. Besides the analysis of SNR of the LDV, diverse optical configurations and signal processing methods have been reported in the scientific literature and by commercial manufacturers.…”