Today I tried to align a cavity with folded geometry as shown in the picture.
The cavity has asymmetric cavity length where the longer one is about 60 mm and the shorter is 15 mm.

Eventually I could see the transmitted flash as attached picture.
Therefore, it may be possible to lock the cavity with a folding mirror though I have not checked the finesse nor transmitted power.

Tomorrow I will estimate the finesse with folded geometry and try to lock the laser using the servo.