Design Of A Single-CCD Dual-optical Path Laser Triangulation Online Thickness Measurement System For Wide-film

Nowadays, Lithium battery is a relatively ideal mobile power. It’s widely used inportable electronic products, Electric vehicles, uninterrupted power supply (UPS), and thepower transmission system, etc. The thickness of pole piece’s coating and its uniformity has adirect influence on the performance of lithium battery, such of its capacity, service life,security, etc. So, It’s very important to measure the thickness of pole piece’s coating online. Inthis paper, some of the existing coating thickness measurement methods were analyzed andcompared. According to the demand of lithium battery coating thickness measurement, asingle CCD dual-optical path laser triangulation online thickness measurement system forwide-film is designed.In this system, the upper (lower) laser beam focused onto the upper(lower) surface,and then the upper and lower two speckles were imaged onto the same CCD through theoptical system. The thickness for measurand can be calculated base on the relationshipbetween the thickness value and the speckles on image plant. However, due to the relativelyindependence of the upper and lower optical path, the light deflection and the nonlinearaberration in this system, the relationship between the thickness value and the speckles onimage plant is no longer simple. According to the imaging characteristics, a non-linear modelis established to correct the relationship between the thickness value and the speckles onimage plant in this system. In this paper, the impact of speckles, temperature and oblique ofobject plane in this system is analyzed through experiments. Some useful solutions also putforward in this paper.The field results show that, in the measurement range, the measurement error of thesystem within±2um, and the repeatability within±1um. So, the accuracy for thismeasurement system can meet the requirements of online thickness measurement for lithiumbattery pole piece coating. Furthermore, this system can be applied to online measurement forother opaque film and sheet. Compared with other measurement system, this system is notharmful to humans, and also higher reliability.