An LED Strobe Scanning System for Enhanced Measurement Accuracy, Flexibility, and Noise Reduction

Conventional laser triangulation measurement (LTM) typically employs a line laser and a precision displacement stage to achieve 3-D measurements. However, as a coherent light source, the laser usually leads to scattering noise, and the mechanical motion of the displacement stage brings about cumulative errors, which limits the measurement accuracy and data reliability. To address these challenges, an improved measurement system based on LED strobe scanning is proposed in this article. The proposed system employs a noncoherent LED rather than a conventional laser source to eliminate scattering noise and incorporates galvanometer scanning for surface profiling to avoid cumulative errors caused by mechanical motion. To realize LED-based strobe scanning measurements, the proposed system initially shapes the LED light into a longitudinally uniform, laterally focused stripe using a dual freeform lens. Subsequently, the system adjusts the working distance through a cam mechanism. Additionally, the system encodes the LED and galvanometer signals via a lower computer to implement strobe scanning measurements. Compared to the traditional LTM system, the experimental results show that the measurement accuracy of the system proposed in this article is increased by more than 60%, the signal-to-noise ratio (SNR) is enhanced by over 13%, and the roughness of the measured point cloud is reduced by more than 63%. The proposed system provides a more accurate, flexible, and low-noise 3-D measurement solution.