Effects of fictive temperature on mid-frequency waviness in laser polishing of glass

Laser polishing of glass optical elements is considered to be a promising processing technology. However, mid-frequency waviness (MFW) is an important defect affecting the practical application of laser polishing. The formation mechanism of MFW has been studied in different aspects. Here, the correlation between fictive temperature and MFW caused by laser polishing is studied on fused silica for the first time. We heat the fused silica samples by a CO2 laser and quench them in air to simulate different fictive temperatures. Then the changes of the Si-O-Si bond angle are measured by a Fourier infrared spectrometer, which is associated with the density of glass. Combining experimental data and laser polishing temperature field simulation, we could find that, although it is not the main factor of MFW formation, the effect of fictive temperature on MFW cannot be ignored. The result provides a meaningful reference for the process of laser polishing glass optical elements.