ETMY HWS source replacement notes: 51nanoL, 520nm laser source

Converted 51nanoL to Class3R by injecting it directly into fiber-coupled splitter. Output power of each port is 0.17mW due to excess insertion loss from FC/PC coupler instead of FC/APC coupler. Expected output power from each port is 2.5mW at 520nm.

 

1118 - At ETMY, getting set up on go onto ALS/HWS table. ALS laser is OFF. Using T1900654 as guide for work. On table with fan on.

1123 – ETM HWS MEDM screens have reverted to old versions with no control of LED light source. 

1132 – Adjusting the launch irises to be centered on the existing HWS beam

1136 – Lens 1 (closest to ETMY): PLCX-50.8-1030.2

Lens2: PLCX-25.4-1030.2

Lens3: PLCC-25.4-257.5

 

1137 – Distances between optics

LPMtoPBS: 305mm

PBStoM1: 65mm

M1AtoM1B: 113mm

M1BtoM1C: 25mm

M1CtoL1: 83mm

L1toL2: 610mm

L2toM2: 38mm

M2toM3: 67mm

M3toM4: 662mm 

M4toM5: 68mm

M5toL3: 261mm

L3toM6: 323mm + 3mm BS

M6toHWS: 629mm

 

1149 – Summary

LPM to L1: target: 570, measured: 591

L1 to L2: target 610, actual 610

L2 to L3: target 1079, actual: 1096

L3 to HWS: target 903, actual 955

 

1153 – Removed existing LED source and existing unlabled lens (which looks to be about 120mm focal length)

1207 – Added and labeled new f=75mm collimating lens

1227 – Laser on table and 50/50 coupler installed. Final version should be off-table and in a box that converts it to 3R with a single mode fiber output coupler.

1251 – Laser going through optics. Gets elliptical if collimating lens is twisted.

1303 – Got return beam from ETM. Still need to collimate outgoing beam and image correctly.

1519 – Back at ETMY. Going to measure beam profile and beam convergence.

Distance from source to lens L3

• COLLtoSM1 = 175mm
• SM1toSM2 = 363mm
• SM2toBS = 240mm
• BStoL3 = 85mm

TOTAL = 863mm

 

Adjusting beam from source to converge at a point 91mm past the lens L3

 

Using beam scan

1544 – Cleaned up beam on BeamScan to be centered in aperture

Looks single mode

 

Measurement 1: translation stage = 2.62 units

W1 = 6.8mm, z1 = 327

W2 = 5.5mm, z2 = 505

Delta = 7”

Puts focus 395mm past L3

 

Measurement 2: TS = 3.00units

W1 = 6.79, z1 = 327

W2 = 4.45, z2 = 505

Puts focus -20mm past L3

 

Suggests going to 2.90 units

Measurement 3 = 2.88units

W2 = 4.82

W1 = 6.86

Puts focus 58mm past L3

 USING this

 

1603 – now adjusting the aligment so it’s centered on the optics

Looks quite large going through the iris on the periscope

 

1618 – got return beam on HWS

• Looked clipped – aligned steering mirror input vaccum system to minimize clipping
• Aligned steering mirror before HWS to center on the HWS.

 

Nominal solution for HWS imaging of test mass (based on measured distances between lenses this is an estimate of how much we need to move the HWS along the optical axis, DZ, to image the ETM onto the HWS)

DZ nominal for HWS = -176mm, approximately 7”

Still a lot of noise on return beam. Adding a 2" beam tube (snout) onto the HWS cut down on a lot of ambient light coupling into the HWS.

Did basic test of imaging by looking at shadow of AERM move as we pitched the ETM. Try to do proper imaging tomorrow.