A thickness measuring device of metal sheet based on dual triangulation through side irradiation with single camera

A classical thickness measuring device based on dual triangulation places the laser sources over and under the sample. According to reports from factories, the tail warping of the metal sheet usually strikes the laser sources and damages them. In order to solve the problem, the dot laser sources are replaced by laser light section generators and placed on the side to avoid the tail warping crash. Moreover, only one camera is employed to monitor both upper and lower line faculae simultaneously, which solves the asynchronism problem. The optical structure and measuring mechanism of the improved device are described in this paper. A nonlinear fitting is utilized to calibrate the device, and the experimental result reveals that the maximum relative error is lower than 1.6% when the measured thickness ranges from 0.2 to 1 mm. Furthermore, even if the object is inclined within 5°, the maximum relative error is still lower than 2.55%.