Misalignment Effects on Power Gathered by Optical Fiber Pyrometer

This article presents a model for analyzing the effect of misalignments in the optical power gathered by a single-color fiber-optic off-axis pyrometer when there is a tilting angle between the longitudinal fiber axis and the plane of the emitted surface. The model takes into account the fiber parameters, such as the diameter and the numerical aperture, as well as the target object size and measuring distance. Simulations show the simultaneous influence of tilting angle and lateral displacement. This provides key behavioral insights to guide alignment and calibration, helping to avoid temperature measurement errors in advanced manufacturing. The model allows integration of the emissivity angle dependence. Results show that the influence of lateral misalignment is negligible for values below 15 µm (which is 1/10 of the 150 µm minimum distance) when considering a 160 µm object size and a 60° tilting angle. The displacement influence, for a fixed tilting angle, is higher in specific directions of displacement.