Distance Measurement Utilizing Image-Based Triangulation

This paper describes a distance-measuring sensor that utilizes image-based triangulation. The angle toward a laser spot changes with distance and is converted into a distance with the help of a calibration procedure. The sensor removes the background illumination with a linear polarizer, a bandpass filter, and knowledge of the line on the focal plane that the imaged laser spot moves along. The sensor utilizes a charge-coupled device detector and an eye safe laser. The sensor operates up to a distance of 10 m. The accuracy of the detector is 1.5 mm at 1 m distance, decreasing to 8 mm at 4 m distance. The sensor is able to track targets at velocities faster than 3.6 m/s at distances up to 4 m. The acquisition time for a target is typically 50 ms and update rates range from 6 Hz at 8 m distance for a low-reflectivity target to 340 Hz at 1 m distance for a high-reflectivity target.