Last week, when we tried to superpose the infrared and green beam on the bench, we just put a CCD camera on the transmission of the dichroic mirror. Since the green power is larger and easier to see, so there are much stronger green power in the infrared path, which is not useful anymore after we align the beam well. So yesterday we put a mirror which can reflect green at 45 degree before the CCD camera to remove it. The original plan is to put another beam splitter after this mirror to separate the beam into two, one for CCD, the other for PSD, the same as the green path. But after I tried to put the beam splitter, I cannot see any infrared both in the reflection and transmission with the CCD. So we gave up with this idea and just stopped with the mirror installed.
We tried to calibrate the AOM again. Since the PD has too much effect on the power fluctuation, we decided to put two power meter in 0 and 1st order, so when we change the RF power, we can see the difference between these two orders. But we cannot find a good position to put the power meter that two order is separated enough and also the beam size is smaller than the aperture of the power meter. So we put another beam splitter after the MZ BS, and two power meter on two path of this beam splitter. Then with spectrum analyzer, we did the ratio between these two power in time domain to see the real change effected by the RF power.