Research On Laser Gauge Method Of Film Thickness

With rapid development of scientific engineering technology and social production, polyester films are more and more widely used. The film manufacturing industry is in great need for secure, precise and non-contact film thickness gauging method. This thesis studies un-touch online film gauge methods in such a situation,With comparison and analysis of current non-contact film thickness gauge solutions and study of optical characteristic of films, the infrared energy absorbance method is chosen. Based on this method, the thesis designs the infrared laser film thickness gauging experiment platform, also, the infrared laser, photo detector and experimental film objects are selected based on comparisons. To avoid influence of all kinds of background stray light and other electromagnetic disturbance, this thesis drives infrared laser source with a pulse signal. To treat the signals, a preamplifier and a corrective detection circuit consisting of a synchronization integrator and correlator are designed; the corrective detection circuit is in charge of processing corrective calculation of signals acquired by photo detector. This thesis also solves problems in debugging and makes improvement of the platform based on demands of experiment. Based on the platform, experiments against half-hardened PVC film, card protection film, antibacterial film, PVC film and magnetic-roll-tape film are made; all results are concluded, analyzed and summarized.The results of all 5 films shows excellent repeatability, curves of half-hardened PVC ,card protection film , antibacterial film , PVC film are quite linear which proved infrared energy absorbance method is quite fitful for thickness gauging of polyester films , also, it can be used to gauge other slim materials which gives this method a widely appliance prospects.