Yuhang and Michael

We did a quick measurement of the new incoupling mirror using the OPO replacement setup in ATC. The incoupling mirror was placed with the convex side facing forward in the mirror mount. The beam was reflected at a low angle (approximately 10 degrees), which is within the specified incident angle tolerance. Reflection and transmission were measured on both faces of the incoupler.

Using thorlabs power meter, we obtained:

Forward mount

Incident =   6.58 mW
Reflected =  6.07 mW (92.2%)
Transmitted = 0.537 mW (8.1%)

Reverse Mount

Incident = 6.64 mW
Reflected = 6.04 mW (91.0%)
Transmitted = 0.535 mW (8.1%)

The power meter is imprecise when being intermittently moved around between measurements - certain beam spot positions around the edge of the power meter seem to record more power (also noted during a previous measurement of OPO nonlinear gain in TAMA)

Very rough measurement obtained by focusing ceiling lights onto the table indicates the focal length to be approximately 15cm.