Modeling of Laser Scanning System to Determine Its Associated Uncertainty of Measurement

In the fabrication of fine wires such as filaments of lamps and optical fibers, it is always necessary to measure the diameter in real-time and correct the extrusion process. For metrological purposes, laser beam scanning technique will produce similar results as comparative to diffraction-assisted methods. A computerized laser beam scanning measurement system (LSM) is designed and fabricated. The LSM consists of a low power helium-neon gas laser source, a specially designed collimating lens, a hysteresis synchronous motor, a photo detector and a protective replaceable window along with temperature sensor. The LSM is mathematically modeled to identify various error contributing sources. The LSM is calibrated using a set of national reference standard cylindrical pins and a set of national reference standard slots to determine its relative calibration factor. The uncertainty of measurement achieved in the range of (0–35) mm is ± (0.55 +39.2L/m) µm.