Optically scanned laser line sensor

This work presents the system design, motion control and the evaluation of an optical scanning system, which manipulates only the illumination path of a laser line sensor by a galvanometer scanner. The selected system design minimizes aberrations due to the optical scanning through the scanner placement. The surface profile is reconstructed from the measured quantities and the model parameters using geometrical relations. An adapted triangular scan trajectory, which features a constant scan speed, is used to scan the sample, such that a uniform lateral resolution is achieved. To follow the scan trajectory a PID feedback controller with a closed loop bandwidth of 305 Hz is designed. The field of view of 31x36 mm is obtained with a resolution of 300x400 pixels. The scanning system achieves a framerate of up to 0.67 frames/s. Experimental results show that the achievable resolution is comparable to the one of a classical mechanical scanning system.

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