传统的激光三角法测量玻璃厚度时,玻璃与测头的相对位置需保持固定,每当玻璃位置移动时,均需重新标定才能进行准确测量。针对这一问题,提出可自适应位移变化的玻璃厚度激光三角测量方法,玻璃在不同位置时均可以直接对玻璃厚度进行测量。首先分析当玻璃位于基准位置时,其前、后表面反射光的成像光斑间距与玻璃厚度之间的关系;其次分析当玻璃位移变化时,成像光斑间距与玻璃前表面位置、玻璃厚度之间的关系,建立数学模型,并相应地提出修正算法来消除玻璃位移变化对厚度测量的影响;最后设计了基于激光二极管-互补金属氧化物半导体(LD-CMOS)的激光三角测量系统,并采用多块已知厚度的玻璃样本进行标定和测量实验。实验结果表明,当玻璃位置在1~4.5 mm的范围内变动时,不同位置处玻璃厚度测量的绝对误差小于0.010 mm,并且相对误差均在0.5%以内。该方法实现了玻璃在不同位置时对玻璃厚度的高精度测量,无需重复标定,具有很好的实用性、灵活性和通用性。

When we measure glass thickness using the traditional triangulation method, the relative position of the glass and probe should be kept fixed. When the position of the glass changes, it must be recalibrated to accurately measure thickness. To address this problem, a multi-position glass-thickness-measurement method based on laser triangulation that can automatically adapt to displacement changes is proposed in this paper. By this method, glass thickness can be measured directly when glass position changes. Firstly, the relationship between the glass thickness and spacing of imaging spots of the reflected light from the front and back surfaces of the glass is analyzed when the glass is at the standard position. Then, the relationship among the spacing of imaging spots, position of front surface of the glass, and glass thickness is analyzed when the glass displacement changes. The corresponding mathematical model is established, and a compensation algorithm is proposed herein to correct the influence of the glass displacement change on the glass-thickness measurement. Finally, a laser triangulation system based on a laser-diode-complementary metal-oxide semiconductor (LD-CMOS) is designed, and multiple glass samples with known thicknesses are used for calibration and measurement experiments. Experimental results show that when the glass position changes within the range of 1-4.5 mm, the absolute errors of glass-thickness measurement at different positions are less than 0.010 mm and the relative errors are within 0.5%. The proposed method can thus realize high-precision glass-thickness-measurement without repeated calibration when the glass is at different positions, displaying good practicability, flexibility, and versatility.