The Laser Doppler Velocimetry technique has been widely used for dynamic
measurements and experimental modal analysis. A laser scanning system that provides
position accuracy, speed, and flexibility plays a key role in this technique. This thesis
gives an overview of various laser scanning techniques and the requirements of a laser
scanning system for the LDV and modal testing. The G3B/DE2488, a most-advanced
galvanometer-based laser scanning system manufactured by the General Scanning Inc., is
one of the most suitable laser scanning systems for the LDV and modal testing. The
focus of this work was to test and calibrate such a scanning system to meet the
requirements for modal testing. A new method to determine laser scanning angles was
introduced. Based on this test method, a laser scanning system test rig was designed and
constructed. To determine a laser bealTI scanning angle, the laser and scanner together
were translated in a direction perpendicular to the target plane by using a micrometerdriven
translation stage. The translation of the scanned laser spot at the target plane due to the translation of the laser-scanner unit was traced by a photodetector and another set
of micrometer-driven translation stages that moved in the target plane. The laser beam
scanning angle was calculated from the traveled distances of the laser-scanner unit and of
the laser spot at the target plane. The test setup was used to determine the overall
performance of the G3B/DE2488 which included the scanning time and accuracy. The
errors that affected the scanning accuracy were analyzed. Due to the relatively low
precision and quality of the cost-constrained equipment used in the test setup, the
accuracy of determining a scanning angle was not very high (around 50 µrad). However,
if some high-accuracy and high-resolution equipment such as a beam profiler and a set of
motor-driven stages are used, this test method has the potential to detennine a laser beam
scanning angle with an accuracy in the order of microradians.
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