A beam diameter of 18 mm is relayed at a magnification of 1.2x without vignetting (1% loss). That means for a Gaussian beam, the maximum input size at 1/e² is defined as 12 mm. With a magnification of 1.5x, a maximum beam of 11 mm (1/e²) can be expanded by the optic, and at 3x magnification, the system allows a free incoming beam diameter of 9 mm (1/e²).
The beam expander is designed as a diffraction-limited Galilean system without internal focus and consists of four high-grade fused silica lenses coated with a broadband low absorption coating to decrease the thermal focal shift.
Also a version designed for the wavelength range of 515 nm – 545 nm is available and furthermore a motorized version (S6EZM5412/328) has been added to our product range.