[Vicky, Regina, Dorotea, Sheila]

We looked at the IR seed light transmitted vs reflected ratio through the OPO to see if any losses can be inferred by this ratio degrading through this past year. We're also unable to probe the IR losses in real time so we trended back over a year and grabbed data points (plot here). Dorotea's follow up post will look at green losses in the OPO cavity which are easier to see since green light enters the OPO cavity through M1 with R1_532 ~98%. This log is trying to look at red OPO losses (which are squeeze losses in the form of degrading OPO escape efficiencies). But this measurement is effectively injecting IR light at M2, which is highly reflective at R2_1064 ~99.9%, so losses will look like a slight change in this trans/refl ratio, which is already very small. 

 

Our measurements do not rule out that we're seeing loss, but it's hard to infer it from this measurement alone. We probably don't have enough consistent data points to see the trend of the transmission vs reflectance ratio over time. 

 

Related alogs of on-table measurements of the trans/refl ratio through the OPO: