Tracking laser Doppler measurement for velocity of moving target

This paper presents a novel tracking laser Doppler velocimeter that can achieve precision measurement of the target´s velocity along the optical axis. To meet the needs, we designed a feedback control system and the Pseudo-Random Sample Consensus algorithm, which are able to ensure the rapid identification and automatic tracking of the target. In addition, employing the retroreflective sheeting makes contribution to the long distance measurement. Experimental results showed that the velocimeter can achieve the accurate measurement of the target along the optical axis at the velocity of sub-micron level with the measurement error less than 0.5% as well as the measuring distance greater than 50m. Also, the velocimeter utilizes the automatic tracking function to achieve the in-plane movement monitoring of the target, which, to a certain extent, makes the target monitoring extend from two-dimensional plane to three-dimensional space. Meanwhile, this paper also gives an improved measurement scheme which can improve the measurement accuracy to the nanometer level to meet the needs of more sophisticated applications. The velocimeter can be used in the fields such as landslide monitoring, structure deformation detecting for bridges, dams and other projects. The high-precision, real-time, continuous monitoring data attained by the velocimeter can help to understand the movement of the target more accurately and establish the better movement model.