The current beam path on IOT2L goes first through an uncoated optics which dumps most of the power. According to alog 6301 and T1600107 the reflected beam is about 3%. The reflected beam is then about 60mW with 1.85W unlocked and maybe about 20mW at 35W locked.

Next a halfwave plate and polarization wedge are used to attenuate the beam further. In the current setup we are attenuating by about ~5. In order to increase the power on the IMC REFL photodetector by ~10 and keep the power in the wavefront sensors roughly the same, we would need to adjust this ratio to 1. Alternatively, we could simply remove the the polarization wedge and use the halwaveplate to give us s-polarization.

Downstream of the power adjustment, half the light is split towards the IMC REFL photodetector, whereas the other half is divided between the 2 wavefront sensors and a camera. The camera path takes about 5% of the light. We would need to replace this beamsplitter with a 90:10, which would reduce the light towards the wavefront sensors by 5. This setup would effectively increase the IMC REFL PD power by ten and double the power in the wavefront sensor path.

A trigger photodetector needs to be installed as well.