Features of high-precision measurements of laser beam lateral displacements in hybrid 3D scanning fiber-optic measuring heads

Abstract

The article discusses the features of using a feedback sensor based on an acousto-optical (AO) laser measuring system (LMS) for high-precision control of transverse displacements of the laser beam in hybrid 3D scanning adaptive fiber-optic measuring heads. Scanning circular movements of a laser beam with a frequency of 1, 5, 10 kHz, formed by a miniature fiber-optic piezoscanner, are considered. Two working sections are created from the circular trajectory formed by a moving laser beam, which are its orthogonal projections, and the current position of the optical spot of each of them is measured in AO LMS. The frequency and accuracy parameters of the AO LMS for traveling ultrasonic waves excited in the AO modulator used as a measure (ruler) are analyzed. The dependences on the length of the ultrasonic waves of the Doppler frequency range, the signal-to-noise ratio of the photodetector, the phase error and the error of transverse displacements, the number of distinguishable angular deviations within 180°, and the spatial resolution are determined and analyzed.