J. Freed,
Today, with the gracious help of K. Kawabe, I took power meaurments of the SPI Pickoff BS (BST11) and its spare using S-polarized light
| Optic | Reflected Power | Transmited Power |
| Main optic (TP03547140) | 77% ± 7.7% | 21% ± 2.1% |
| Spare(TP03435437) | 76% ± 7.6% | 22% ± 2.2% |
| Expected values from ThorLabs | 81% | 18% (BST11_Data.xlsx) |
Due to the limited time and person power, we used a S121C PD to take these measurments, which we now realize has a 7% uncertainty at 1064nm with a >1mm diameter beam. Although we relized that the beam was too large after we finished the measurment of the main optic and added a lens to focus the beam during the spare measurement, we have no idea if the beam was ever below the 1mm threashold. As such even though we were using a PM100D power monitor which has a resolution of 0.1 mW, we have to quote an uncertainty of 10% of the final value for our meaurments. This is colaberated by the fact that mulitiple measurments of the same beam could yeild different reults when the PD was taken out of the beam path and put back in, but remained steady if left alone.
SPI-BS-PWR_MEAS.png Shows the measurment set up. The only pick off that was available was p-polarized, as such, we added another half wave plate/PBS combo to get S-Polarized light to our BS
There also existed a ghost beam from the AR-Coated wedge side of the BS that was not taken into acocount for the main optic but was for the spare. Though we dont think the ghost beams affected this measurment as they were 3 orders of magnitude of power below the main beams.
SPIPBSRATIOMEAS-3.txt is a text file containing extra notes as well as the power values measured. The power ratios were found by taking an average of all the trials and then divided by the power we measured just before the beam splitter.
