Naoki, Sheila

As part of noise budget with 75W, we did laser noise injection (frequency noise, intensity noise, jitter noise). Here is the instruction of laser noise injection.

The injection templates are in ligo/gitcommon/NoiseBudget/aligoNB/aligoNB/H1/coupling.

Frequency noise

template: Frequency_excitation.xml

Switch CARM control from REFL A+B to REFL B only:

• REFL A and B both have 9dB digital gain with 75W
• Step down 1dB on REFL A and up 1dB on REFL B until the REFL A gain is 3dB and REFL B gain is 15dB
• Step down REFL A gain down to -32dB 
• Turn off the input 1 switch (REFL_SERVO_IN1EN) for REFL A

Measurement:

• Take the reference without excitation and update the reference
• Plug the cable to the excitation port of CARM CMB in PSL rack and turn on the digital excitation switch (EXC A) of CARM CMB
• Start injection
• After the measurement, turn off the digital excitation switch, unplug the excitation cable, and bring back the CARM control

Intensity noise 

template: ISS_excitation_LF.xml, ISS_excitation_MF.xml, ISS_excitation_HF.xml

• Turn off the 10Hz pole in ISS second loop (PSL-ISS_THIRDLOOP_POLE_MON), and put 1 in the digital excitation gain (PSL-ISS_SECONDLOOP_EXCITATION_GAIN). The 10Hz pole and the digital excitation gain can be accessed from medm screen of ISS second loop as shown in the attached figure
• Take the reference without excitation and update the reference
• Start injection
• After the measurement, bring back the 10Hz pole and the digital excitation gain

Jitter noise

template: IMC_PZT_P_inj.xml, IMC_PZT_Y_inj.xml

• Take the reference without excitation and update the reference
• Start injection