Compact disc laser cleaning for polycarbonate recovering

In this research work, laser cleaning of Compact Discs (CDs) through the employment of a 30 W MOPFA Q-switched pulsed Yb:YAG fibre laser is investigated. The laser beam is used to ablate the metal substrate located between the polycarbonate layer and the outer serigraphy of CDs with the final aim to recover the polycarbonate layer and make it available for further applications. Compared to traditional cleaning processes, this method offers several advantages, including: absence of mechanical contact, reduction of secondary pollutants, low energy consumption, greater flexibility of use and possibility to work small batches. Two experimental test series were carried out. First, linear scans were executed at the maximum average power (30W) by changing scanning speed and pulse energy. The width of the ablated material was then measured on the test CDs. Furthermore, the mechanism of separation between the deposition layers and the polymer substrate is observed and described. The second experimental testing series was performed to identify the process conditions that could ensure a 100% cleaned surface without polymer degradation and to evaluate the corresponding process time. On the basis of the test results, three different conditions were observed: incomplete cleaning, complete cleaning and cleaning with polymer degradation.