4/10/25 Power ratio measurements of the SPI pickoff beam splitter (BST11) using S-polarized light.

First optic TP03547140
Beam Power 32.2mW Was max
30.7mW when it was centered

We believe centering is more correct than finding max power as max power may be caused by some sort of extra reflections

Background light 0.1-0.2mW with an extra 1 uW dark noise So we turned of the lights

Reflected is 23.5mW Centered
Transmitted 6.42mW Centered

Round 2 
Full 30.2MW Centered
Ref 23.4 mW Centered
Tran 6.4 mW Centered

Round 3
Full 30.2mW Centered
ref 23.5mW Centered
Tran 6.47mW Centered

Ratio: T 77.3% R 21.2%
Ratio: T 75.6% R 22.5%

4/11/25
Second optic TP03435437
Round 1
full 25.4mW
ref 19.4mW ghost beam is 25um lights on 19um lights off
tran 5.75mW 4.24um ghost beam
Round 2
full 25.9 mW
ref 19.4 mW
tran 5.80mW