Beam expander optics increase output beam diameters to 300–600 mm
Large-output beam expander modules use an air-spaced lens doublet input coupled to a large spherical lens to increase the diameter of a collimated input beam (50–100 mm) to a larger output beam (300–600 mm). Enabling interferometers to test optical flats up to 600 mm diameter, typical wavefront distortion is > λ/10.
Optical Surfaces
Kenley, U.K.