During yesterday shift the cross-talk between the INJ and DET SLEDs has been investigated.
After switching off the DET-SLED, we have measured the power of the INJ-SLED arriving on HWS-DET (order of 4uW wrt an input power of 130uW). We have also measured the power of the beam reflected back from the WI on the proper HWS-INJ equal to 26 uW.
Then we have adopted the same procedure to evaluate the extra-light coming from the DET-SLED on HWS-INJ and we measured approximately 30nW wrt an input power of 1.9 mW. The light power reflected back from the NI on the proper HWS-DET was approximately of 0.1 mW.
These measurements will be used to fine-tune the decoupling strategy between the two SLEDs.