Planar Water-Cooled Reflective Copper Mirror

Planar Water-Cooled Reflective Copper Mirror

The planar water‑cooled reflective copper mirror is an optical element that operates on the principle of light reflection. It redirects the incident laser beam in different directions to enable beam delivery and focusing. The integrated water‑cooling design allows high‑power operation, extends the mirror’s service life, reduces the frequency of replacement, and lowers maintenance costs, making it suitable for kilowatt‑level and above laser processing applications.

Material & Process

The mirror is fabricated from a copper substrate with a thermal conductivity exceeding 400 W/(m·K), which rapidly conducts away heat generated by laser irradiation. Together with the water‑cooling system, this ensures thermal balance, preventing surface deformation or coating degradation. Some versions use a nickel‑copper alloy (NiCu) substrate to enhance mechanical strength and corrosion resistance.

The optical surface is finished by diamond turning or precision lapping, achieving a surface figure of λ/4 PV (@633 nm) and a surface quality of 20/10 (scratch/dig). This guarantees phase stability of the reflected beam and compatibility with beam‑control requirements for both fiber and solid‑state lasers. A hard gold coating (typically 0.1–1 μm thick) is deposited on the polished substrate, providing a reflectivity Ravg >99.5% (@10.6 μm) and improved scratch resistance.

Enhanced Metallic Reflective Coating, Reflectance >99.5% at 10.6μm

（Note：X-axis represents wavelength in micrometers, Y-axis represents reflectance percentage.）

Water‑Cooling Design

Cooling channels are embedded inside the mirror body. Circulating water or a specialized coolant removes heat, raising the laser power handling capacity to the 20–40 kW range. Selected models incorporate independent cooling circuits for both the mirror face and the mounting base, further improving thermal management and extending continuous operation to hundreds of hours or more.

Applications

This mirror is suitable for fiber lasers (1–40 kW) and CO₂ lasers operating at 10.6 μm and near‑infrared wavelengths, meeting the requirements for efficient and stable processing of stainless steel, aluminum alloys, and other materials. It is widely used in laser welding cladding, additive manufacturing, laser quenching surface modification, laser edge banding, laser heating, and related processes.

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