Beam expander

The main advantage of the Galilean design is that it never focuses a collimated beam to a point, so effects associated with high power density such as dielectric breakdown are more avoidable than with focusing designs such as the Keplerian telescope.

[1] In tunable laser resonators intracavity beam expansion usually illuminates the whole width of a diffraction grating.

Designs applicable to tunable lasers with beam expansion factors of up to 200 have been disclosed in the literature.

[3][10] These matrix equations are applicable either to prism pulse compressors or multiple-prism beam expanders.

[3][11] The resulting plane illumination, with a near one-dimensional (or line) cross section, eliminates the need of point-by-point scanning and has become important for applications such as N-slit interferometry, microdensitometry, and microscopy.