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22 June 2015 Length characterization of a piezoelectric actuator travel with a mode-locked femtosecond laser
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The development of absolute distance measurement methods have been enabled by new kind of lasers, special digital signal processing electronics, algorithms and new materials for optics. The phenomenon of the mode-lock of the femtosecond pulse laser increased a number of potential applications with distance surveying where that stable generator of very short and periodically repeated coherent pulses can be used. The main aim of the work is a description of precise measuring method with absolute scale which is able to determine the length of unknown distance with direct traceability to a time standard. The principle of the method is based on a passive optical cavity with mirrors keeping measured distance, in our case a piezoelectric actuator. Time spacing of short femtosecond pulses generated by mode-locked laser is optically phase locked to the cavity free spectral range. A value of the repetition frequency of the laser determines the measured distance. The exact value of the frequency/period of the femtosecond pulse train is detected by a frequency counter. The counting gate of the counter is synchronized with a highly stable oscillator disciplined by H-maser or GPS received signal from atomic clocks. The work shows methods how to overcome problems with dispersive optics in the passive cavity and a way of phase lock of the femtosecond laser repetition rate to free spectral range of the cavity. This measuring technique is demonstrated on length characterization of the piezoelectric transducer which belongs to ultra-precise positioning actuators.
© (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Lenka Pravdová, Adam Lešundák, Václav Hucl, Martin Čížek, Břetislav Mikel, Jan Hrabina, Šimon Řeřucha, Ondřej Číp, and Josef Lazar "Length characterization of a piezoelectric actuator travel with a mode-locked femtosecond laser", Proc. SPIE 9525, Optical Measurement Systems for Industrial Inspection IX, 95254K (22 June 2015);

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