Laser removal of paraffin wax from glass surfaces

Waxes and thermopolymers are commonly used to mount optical and photonic materials prior to polishing and singularization. After demounting, residual wax/thermopolymer can adhere to the component surface, frequently in the form of particles. Dry, ultraviolet-pulsed laser cleaning has been demonstrated to effectively remove paraffin wax particles, prepared on a glass surface using a wax aerosol technique. This method produces dome-shaped particles. Experimental evidence suggests the dome-shaped particles are vaporized by the absorption of the energy from the laser pulse. A theoretical model based on vaporization has been developed and this leads to predictions of the critical fluence for single laser pulse removal of dome-shaped particles which is in good agreement with that experimentally measured (220mJ/cm ²). The model also gives insight into the geometries and relative thermal properties of the "particles" and surface, which are important in determining whether removal by vaporization is a viable process.