Research On New Method Of Measuring Parameters Of Laser Holographic Anti-Counterfeiting Labels

The laser holographic anti-counterfeiting label (LHACL) is a kind of anti-counterfeiting products. It plays an important part in inhibiting forgeries of name brands, credit cards and securities. But its anti-counterfeiting ability is being impaired by irregular qualities. Accordingly, the research interest on how to measure characteristic parameters of the LHACL accurately to improve its quality is booming.According to the state-specified standard, the quality of LHACLs is to be assessed by measuring their diffraction efficiency and SNR. But up to now, this assessment is difficult to be realized accurately and efficiently, owing to the lack of specialized instruments. The primary characteristic-parameter measurement instrument designed by our team suffered from its high cost and huge volume, which limit its accuracy and popularization.In this paper, a non-deviation real-time method, with lower requirement for the stability of source light, was proposed to measure the characteristic parameters of LHACLs. And a measuring device with higher accuracy and lower cost was designed, with the integration of automatic measurement, calculation, data display and storage.The main work of this paper includes:A low-cost high-precision measuring method was presented to measure the diffraction efficiency and SNR of LHACLs, which measures the intensity of the incident light in real time to reduce the dependency on the stability of the source light.The optical system was improved. And a mechanical system was designed to fix and control the optical system. Circuits and software components were designed, including C51-based controlling component, automatic sample platform, light-to-current conversion, data acquisition and processing, A/D conversion, LCD display and USB data storage.The characteristic parameters of 150 random samples were measured by our system. The measurement error of the incident light was less than 0.2%, due to which that of characteristic parameters was significantly reduced. With lower measuring cost and easily being instrumentation, the new system provides warranties for further researches on the assessment of LHACLs and the improvement of the nation-specified standard.