A real-time sub-μrad laser beam tracking system

Abstract

We present a rugged and reliable real-time laser beam tracking system operating with a high speed, high resolution piezo-electric tip/tilt mirror. Characteristics of the piezo mirror and position sensor are investigated. An industrial programmable automation controller is used to develop a real-time digital PID controller. The controller provides a one million field programmable gate array (FPGA) to realize a high closed-loop frequency of 50 kHz. Beam tracking with a root-mean-squared accuracy better than 0.15 µrad has been laboratory confirmed. The system is intended as an add-on module for established mechanical mrad tracking systems.

A System for Precise Laser Beam Angular Steering

“…Systems based on a mirror stilted by piezoelectric elements are usually used owing to the possibility of controlling them with a voltage. They are also highly precise [5,10]. Their angular positioning resolutions are no higher than a few microradians.…”

“…There are numerous methods used for the angular control of the beam: a wedge [3] and window [4], a tilt mirror [5][6][7][8][9][10] a mirror matrix [11,12] and a diffraction grating generated by liquid crystals [13]. Only those systems that do not cause distortion of the beam wavefront, such as tilt mirrors [5,[8][9][10] or wedges [3] can be applied in interference displacement measuring systems. Systems based on a mirror stilted by piezoelectric elements are usually used owing to the possibility of controlling them with a voltage.…”

Atmospheric tip/tilt compensation for laser beam tracking with amateur telescopes

“…6 the main features of cRIO are listed. More detailed analyses of the controller performance and the features of the graphical programming code can be found in [5]. …”

“…We apply a tip/tilt mirror (PI S-330) unit operated with piezo-electric actuators. Characteristics and system properties of the used piezoelectric tip/tilt beam steering mirror PI S-330 manufactured by Physik Instrumente (PI) are described in [4,5].…”