Thermal lensing impact on the focal shift and optical deformation in the cutting head of 1064nm fiber lasers 1–6 kW
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DOI:
https://doi.org/10.15625/0868-3166/22744Keywords:
Thermal lensing, high power laser, cutting heat, fiber laser, focus shift;, 1064 nmAbstract
Thermal lensing is an unavoidable phenomenon in optical systems utilizing high-power lasers, including laser cutting heads, due to energy absorption-induced thermal and optical variations. This study analyzes its effects on a 1064 nm laser system (1–6 kW) using two fused silica plano-convex lenses, with focusing lens focal lengths of 125–300 mm. Simulations indicate a peak lens temperature of 952 K at 6 kW, driving focal shifts up to Δf = −45.4 mm (300 mm focal length) and relative refractive index changes of 74.5–114%. Spot diagram analysis at the focal plane indicates severe beam spreading and optical distortion when the laser power exceeds 4 kW. Proposed solutions include thermally stable materials, enhanced anti-reflective coatings, and real-time focal adjustments to optimize cutting precision.
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