Abstract: In order to meet the requirement of measuring thickness of transparent materials for precision optical lens and glass container, etc., the polychromatic confocal method is used to measure the thickness of transparent material. The measuring principle of confocal system is introduced. A measuring structure scheme is proposed, and an experimental device is constructed and calibrated. The linear regression method is adopted to process the experimental data. The proposed method is to use linear prediction function to construct a mathematical model. The parameters in the model are determined using the measured data. The thickness model is improved by compensating error. The experimental results show that the measuring range of confocal system can reach 15 mm, and the accuracy of measurement is ±3 μm. The compound color confocal method is a kind of online non-contact measurement technique with high precision.

Key words: apparatus and instruments technology, confocal technology, transparent material, thickness measurement, linear regression