Optical EngineeringExtended measurement region differential laser Doppler velocimeter with multipoint illumination
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A measurement region extended differential laser Doppler velocimeter with multipoint illumination was proposed. The arrangement used two types of ruled diffraction gratings to form the extended region with several independent measuring volumes. The measurement model was then given, demonstrating that a solid object passed through a single measuring volume or two measuring volumes simultaneously. Signal processing technique efficiently enhanced the signal-to-noise ratio. Experimental results showed that the measurement range along the optical axis could be extended to 109.73 mm with a beam angle of 9.557 deg. The mean error of velocity ranging from 7 to 13 m/s was 1.52% by using the frequency spectrum correction method. The results indicated that the proposed method has great potential for realizing the velocity measurement of solid objects in a large measuring region.