The perpendicularity of some of the A and M prisms were tested.
- The measurement results are listed as Attachment 1 and 2 together with the comparisons to the measurement in 2013 and the spec provided from the vendor.
- Here, the positive number means that the front side of the prism has larger angle than 90deg for the air side. (i.e. positive number = facing up)
- The RoC of the curved mirrors is 2.5m. Therefore, roughly speaking, 83arcsec corresponds to ~1mm beam spot shift. The requirement is 30 arcsec.
- The A prisms tend to have positive and small angle deviations while the M prisms to have negative and large (~50arcsec) angle deviations.
- The consistency: The measurements in 2013 and 2019 have some descrepancy but not too big. This variation tells us the reliability of the measurements, say +/-30arcsec.
- The photos of the setup is shown as Attachments 3/4/5. Basically this follows the procedure described in Sec 2.2.2 of T1500060.
- The autocollimator (AC) is held with the V holders + posts.
- The periscope post for the turning Al mirror was brought from Downs by Stephen.
- The turning mirror is a 2" Al mirror. The alignment of the turning mirror was initially aligned using the retroreflection to the AC. Then the pitching of the holder was rotated by 22.5deg so that the AC beam goes down to the prism.
- The prism is held on a Al mirror using the post taken from a prism mount.
- If the maximum illumination (8V) is used, the greenish light becomes visible and the alignment becomes easier.
- There are two reflections 1) The beam which hits the prism first, and then the bottom mirror second, 2) The beam which hits the bottom mirror first and then the prism second. Each beam gains 2 theta compared to the perfect retroreflection case. Therefore the two beams have 4 theta of their relative angle difference. The AC is calibrated to detect 2 theta and tells you theta (1div = 1 arcmin = 60 arcsec). So just read the angle defferencein the AC and divide the number by 2 (not 4).
The 9MHz port was tuned and the impedance was measured.
I helped to complete the 5th OMC Transport Fixture. It was built at the 40m clean room and brought to the OMC lab. The fixture hardware (~screws) were also brought there.
Jan 15, 2015 3rd OMC completed
The face caps of the DCPD/QPD cables were installed (Helicoils inserted)
PD7&10 swapped with PD11(for DCPD T) and PD12(DCPD R).
Firct Contact coating removed
Note on the 3rd OMC
Before the 3rdOMC is actually used,
- First Contact should be applied again for preventing contamination during the installation
- DCPD glass windows should be removed
3IFO EOM dark microscope images courtesy by GariLynn and Rich
Attachment1/2: Hole #1
Attachment3/4: Hole #2
Attachment5: Hole #2
3IFO EOM (before any modification) was tested to measure the impedance of each port.
The impedance plot and the impedance data (triplets of freq, reZ, imZ) were attached to this entry.
The 3IFO EOM test performed at the 40m. Result: 40m ELOG 13819
Antonio borrowed: Rich's PD cutter (returned), Ohir power meter(returned), Thorlabs power meter head, Chopper
The 40m Bake Lab's Dirty ABO's OMEGA PID controller was borrowed for another oven in the Bake Lab (sound familiar? OMC elog 377), so I have had to play with the tuning and parameters to recover. This bake seemed to inadequately match the intended temperature profile for some reason (intended profile is shown by plotting prior qualifying bake for comparison).
The parameters utilized here are exactly matching the prior qualifying bake, except that the autotuning may have settled on different parameters.
Options to proceed, as I see them, are as follows:
OMC (002) after repair
History:Mirror replacement after the damage at H1. Measurement date 2019/1/10