I installed the another AOM (S/N:149256) as attached to check its diffraction efficiency with larger beam size compared to previously installed one.
The input beam power was 5.5mW and diffracted beam power was 3.5mW though the RF level was not tuned.
So the diffraction efficiency can be enhanced by larger beam size.

Then I put a concave lens in front of the AOM previously installed whose efficiency was about 50%.
Actually the efficiency was increased to 60%.

I gonna increase the beam size at AOMs to modify the position of lenses to enhance the diffraction efficiency (according to spec sheet, about 85% can be achieved).