Sill Optics has launched large aperture beam expanders, which incorporate fused silica lenses.
High power fibre lasers usually provide a collimated beam with an 1/e² diameter from 6mm to 9mm, i.e. the full beam width can be up to 18mm. A cut-off of the beam would result in a significant loss of energy for the process and the beam expander would heat up.
With clear entrance apertures of up to 30mm, the new beam expanders transmit the entire beam with excellent imaging quality. A divergence setting with high pointing stability allows a proper collimation or a controlled focus or defocus of the beam.