Using geometrical optics theory and off-axis aberration analysis, a set of crossed double strip integrators for high power CO_2 laser beam homogenizing has been designed.

It is hard to design for beam expander with high power and wide aperture required, because it is shorten length, larger aperture, as well as on axis and off axis aberration must be corrected properly.

It may be used to test the on - or off-axis various wavelength wave aberrations, chromatic aberration and other optical performances of various magnification microscopic objective.