Process Parameter Optimization for CO₂ Laser Polishing of Fused Silica Using the Taguchi Method

Area of Science:

• Materials Science
• Laser Processing
• Surface Engineering

Background:

• Fused silica is a critical optical material requiring high-quality surface finishes.
• Traditional polishing methods can be time-consuming and may not achieve the desired nanometer-level smoothness.
• Laser-based polishing offers a potential alternative for efficient and precise surface modification.

Purpose of the Study:

• To investigate the optimization of fused silica polishing using a CO2 laser.
• To evaluate the influence of key process parameters on surface roughness.
• To determine the optimal parameter combination for achieving superior surface quality.

Main Methods:

• Utilized a CO2 laser with a rapid scanning rate to create a line heat source for polishing.
• Employed the Taguchi method to systematically analyze the effects of four process parameters: laser reciprocating scanning length (A), laser beam scanning speed (B), feed speed (C), and defocusing amount (D).
• Performed analysis of variance (ANOVA) to identify significant factors and their interactions.

Main Results:

• Achieved a significant reduction in surface roughness from Ra = 0.157 μm to 0.005 μm.
• Identified the optimal process parameter combination as A1B1C1D1.
• Determined that laser beam scanning speed (B) has a significant impact on polishing quality, with the interaction between factors A and B (A × B) contributing the most (42.69%) to the optimal parameters.

Conclusions:

• CO2 laser polishing is an effective method for achieving ultra-smooth surfaces on fused silica.
• The Taguchi method and ANOVA are valuable tools for optimizing laser polishing processes.
• Understanding the interaction between laser scanning parameters is crucial for precise surface finishing.