The sensors of WE Pcal are calibrated with respect to WSV, it has been installed the 15/11/2022 evening.
17h15 - 17h40 UTC: Installation of the follower circuits, two single ended for WSV, and one differential
17h40 - 18h20 UTC: Calibration of the ADC ports n°5 & 6 with the follower circuits
18h25 - 19h07 UTC: Installation of WSV sphere on Rx sphere
19h13 UTC: Laser switched on, with control loop on Tx_PD1, without permanent lines
No problem has been noticed
During the night from the 15 to the 16th of November, we let WSV on the reflection bench of WE PCal, in order to calibrate the photodiodes Tx_PD1 & 2 with respect ot WSV. The laser command was 1.3 W, in loop with Tx_PD1. Three permanent lines 35 Hz, 60 HZ and 350 Hz were added in the command signal. However, due to an error in the ADC voltage calibration done the 15th, the data taken during the night are biased.
The ADC calibration was done again the 16th at 8h45. And data has been taken from 9h30 to 13h50.
However, the power seen by WSV wasn't stable because the reflected beam moved, due to movements of the end mirror. The WE tower was in air.
WSV is removed the 16/11 at 15h00 in order to install WE_Rx sphere on the reflection bench, at 15h20.
After 16h the WE mirror position can be controlled, so a new calibration attempt with WSV will be done during the night from the 16th to the 17th of November.
The Rx sphere has been instaled on WE on the reflection bench at 15h20.
There is a saturation problem at the output of Rx sphere. The saturation is due to the follower circuit at the differnetial output of the sphere.
The saturation threshold increase if the Vbias generated by the DAC that supply the follower circuit increase. However, the maximum voltage generated by the DAC is +5 V differential.
Therefore laser power is lowered to 1 W.
A 3 bananas - LEMO3 cable can be made, in order to supply the follower circuit with a voltage generator Rohde&Schwartz. The same on the supply the integrating sphere WSV. (+15 -15 V)
The saturation problem doesn't happen on WSV because the output voltages are single-ended.
The sphere WSV has been re-installed on WE PCal bench, at 19h05.
The ADC port that measure the power output voltage of WSV, has been re-calibrated with respect to the time-electronic 1048 voltage generator.
| time-electronic | ADC2378 | keithley |
| 0 V | 16 µV +/- 5 µV | 4 µV +/- 1 µV |
| 1 V | 0.99995 V +/- 0.05 mV | 1 V +/- 0.1 mV |
| 1.8 V | 1.80007 V +/- 0.05 mV | 1.8 V +/- 0.1 mV |
The output voltage is measured by both the ADC2378 and the keithley voltmeter, in order to cross check the voltage calibration. With different laser power in the sphere. The power is in loop with Tx_PD1 photodiode.
| input power | ADC2378 | keithley |
| 0 W | -3.22 mV +/- 0.01 mV | -2.64 mV +/- 0.01 mV |
| 0.5 W | -1.3166 V +/- 0.1 mV | -1.3163 V +/- 0.1 mV |
| 1 W | -2.6284 V +/- 0.1 mV | -2.6280 V +/- 0.1 mV |
| 1.3 W | -3.4119 V +/- 0.1 mV | -3.4115 V +/- 0.1 mV |
| 1.5 W | -3.9390 V +/- 0.1 mV | -3.9385 V +/- 0.1 mV |
The ADC value is ~ 0.5 mV below the keithley volmetervalue. Which represent a bias of 0.015% of 3.4115 V, for a input power of 1.3 W.
The permanent lines are switched on at 20h10. The sphere takes data during the night from the 16th to the 17th of Novenber for PCAL photodiode calibration.
The position of the WE mirror is stabilized.
The 3 bananas - LEMO3 cable has been made and installed on WE, in order to supply the differntial follower circuit. The laser power command is set on 1.3 W, in loop with Tx_PD1, with permanent lines.
There is no saturation of the signal anymore.
