Φ300 Hartmann field flattening laser beam expander

As for laser beam expander with high magnification, wide aperture and fast relative aperture, the off-axis aberrations of Galilean and Keplerian structures are difficult to be corrected. Based on third-order aberration theory, a novel field flattening laser beam expander optical system is presented. An aspheric objective is introduced, and a combined eyepiece of Galilean and Keplerian is put forward. As an example, a laser beam expander with magnification 30, field of view 2mrad, clear aperture of objective 300mm, focal length of objective 800mm, and primary working wavelength 0.6328μm is discussed,. Final test results by laser interferometer show that the PV value of the objective is better than λ/10 on axis and rms λ/90, PV value of optical system is better than λ/8 on axis and rms λ/55.