The high-quality LOWER protective optical glass, with a diameter of 27.9 mm and a thickness of 4.1 mm (JGS1 Fused Silica), is an essential protective component in fiber laser heads. Its primary function is to effectively protect more expensive collimating and focusing lenses from dust, smoke, and molten metal spatter generated in the CNC cutting zone. The use of advanced anti-reflective coatings (AR) with a high resistance threshold prevents the absorption of laser energy, minimizes the thermal lensing effect, and guarantees full focal length stability during operation at powers up to 4,000 W.

The protective lenses feature precise geometric design, smooth, polished edges, and excellent resistance to thermal stress. This specific dimensional standard is fully compatible with a wide range of medium-power fiber cutting heads, including the extremely popular Raytools series (e.g., BT240S, BM109), as well as components from brands such as WSX, Precitec, Bodor, and Gweike.