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.

高倍率及大孔径扩束器要求筒长短、口径大、轴上和轴外的像差都要很好地校正，所以光学系统的设计是非常困难的。

youdao

This configuration is compatible with an Open Rack system to provide an off the shelf SAS expander.

FORBES: Open Source Storage Changes Industry Cost Structure