Glass processing with pulsed CO_2 laser radiation

Abstract

Recent results of processing fused silica using a high-power Q-switched CO₂ laser source with a maximum output power of 200 W are presented. Compared to the processing with continuous wave laser radiation, the main advantage of pulsed laser radiation is the influence of the light-matter interaction with high laser peak power at small average laser power. An application for the approach presented in this paper is the flexible manufacturing and form correction of optics. This laser-based process is nearly independent of the surface geometry and can even be enhanced by laser polishing and expanded to other glass materials. Hence, the high-power Q-switched CO₂ laser source is used to ablate glass material with an ablation rate up to 2.35 mm³/s and also for ablating glass material locally in a vertical dimension down to 3 nm.

Numerical model and experimental demonstration of high precision ablation of pulse CO2 laser

“…For laser figuring, a lateral resolution <100 μm and a vertical resolution <5 nm should be achieved [10] . Several experimental researches have been done to study high precision laser ablation for shape correction by a CW CO 2 laser [11] , ultrashort pulse laser [12,13] , and pulse CO 2 laser [14] . So far, however, it is reported that only a pulse CO 2 laser can meet the high precision requirements of laser beam figuring.…”

“…Therefore, single pulse ablation is sufficient to represent the process. The ablation depth can be controlled through laser pulse duration or incident energy [10,14] . The quality of the final corrected surface is determined by the superposition of single pulse ablation.…”

Numerical and Experimental Investigation of Morphological Modification on Fused Silica Using CO2 Laser Ablation

“…Laser processing is an effective and attractive method for surface modification of various materials, including surface texturing of semiconductors [1,2], corrosion prevention in biocompatible metals [3,4], and surface polishing of optical glass [5,6]. Employing CO 2 laser melting in a non-evaporative regime has enabled us to obtain surfaces of optical glass with a roughness smaller than 0.1 nm at a rapid processing rate of up to 5 cm 2 /s [5].…”

“…Fortunately, for fluctuation with a spatial wavelength larger than 100 µm, Weingarten et al [5,6] introduced the laser-beam figuring (LBF) process to correct errors in the shape of a polished surface of fused silica with a precise and selective material ablation using a pulsed CO 2 laser. In the LBF process, laser ablation is highly localized and the ablation depth is strongly related to the pulse duration, which allows for the elimination of a wide fluctuation (over 100 µm).…”

Consolidation of flame hydrolysis deposited silica with a 9.3 µm wavelength CO 2 laser

“…CO 2 lasers are widely used for machining glass [6,7] and have previously been used for smoothing and polishing of silica [8,9]. These techniques were performed with CO 2 lasers operating with a wavelength of 10.6 µm.…”