the telescope matchs the cold cavity beam, so it is normal to have a power decrease on the transmission photodiode when the cavity is heating at high power. we can try to adjust the telescope by moving lens, one by one, to increase the cavity power.
Beam diameter behind M2 :
- 2nd stage @ 6A - 1kW inside cavity sx = 2120 µm sy = 2150 µm
- 3rd stage @ 3A - 30kW inside cavity
sx = 2260 µm sy = 2475 µm