We calibrate the photodiode (Tx_PD1) on the injection bench of the PCal NE, with the "working standard virgo" integrating sphere (WSV).

We recalibrate the ADC port of the WSV with a tension generator, remove the offsets of the photodiodes and of the WSV.

We put WSV on the reflection bench of the NE PCal, and leave it for the night from 21/09 to 22/09. The laser was on a control loop with Tx_PD1, with a power command of 1.5 W, with power modulations at 34.5 and 63.5 Hz. We recorded the signal of WSV and Tx_PD1, and comput their ratio. We also recorded the X, Y, Z position of the and mirror and the humidity and temperture on the bench. NE_posMIR_Tx_WSV_ratio_vs_time.png

As expected, the ratio between WSV and Tx_PD1 depend highly on the humidity, since there are beamsplitters (thorlabs BSX11) on the benches. It seems to deppend also on the position of the mirror but less. The jump at 2:00 am (UT) is smaller on the ratio than on the mirror position. (see NE_posMIR_Tx_WSV_ratio_vs_time.png). As seen on figure NE_ratio_vs_HU.png the ratio seems to be proportioal to the humidity.

The ratio WSV/Tx_PD1 is equal to 963+/-1 mW/W. The calibration factor of the photodiode Tx_PD1 has been changed with respect of this ratio the 22/09 at 19:55 UT, on the config file. (from -4.932 to -4.752)