Method for on-line measuring thickness of glass by using laser two-way symmetrical transmission way

For the shortcomings of the traditional flat glass thickness measurement, one method which was based on the principle of light refraction, with the dual laser symmetrical transmission method was proposed, and the whole measured system of on-line measurement of flat glass thickness was designed, in which line laser was the light source and the symmetry plane of mirrors were the optical path switching device to modulate the symmetrically distributed optical paths into two parallel line lasers, and a linear array CCD sensor was set as a visual exploration tool, meanwhile, the grey level of the transition area of the background and target was selected as the boundary threshold value of the single beam line's light band image according to the characteristics of captured image, the algorithm for obtaining light band center pixel was made modified gray gravity. After the experiment of the measurement on the sample glass thickness, the results show that the accuracy of these measurement methods can reach to 0.1 mm. The measuring accuracy is correspond with the requirements of the testing standards. Therefore the feasibility is verified, that have a good practical value.