GOALs of this month
1. to stabilize the PSL by taking the green beat note signal and actuating the MC length while assuming the X arm is a stable reference
2. to measure the stability of the beat note and to compare it with that of the IR PDH signal
=> above two actions finally answer the question : the green locking is stable enough to hand off the control servo to IR or not ?
Action Items
Indicators |
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complete
intermediate state 
nothing happened 
gave up
Step 1. X arm alignment for IR |
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action |
description |
status |
notes |
1-A |
setup DC_PD at an available port |
to find a fringe |
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1-B |
align BS, ITMX and ETMX |
to have TEM00 flash |
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put a camera at ETMX_TRANS |
1-C |
place TRANS_MON_PD and QPD |
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1-D |
hook it up TRANS_MON and QPD to ADC |
c1iscex |
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1-E |
make a simple mod/demod system |
to lock the IR |
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1-F |
feeding back the signal to MCL |
to lock the IR |
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1-G |
add a LOCKIN module into c1sus and c1iscex |
for A2L |
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1-H |
A2L for IR |
for precise alignment |
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C1ASS does |
put Thorlabs PDA255 at AS
Step 2. Re-alignment of green |
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action |
description |
status |
notes |
2-A |
change beam axis |
steer the mirrors at X end |
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2-B |
rearrange the optical setup at X end |
if necessary |
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2-C |
lock the green to X arm |
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2-D |
more precisely overlap the green beam axis to the IR |
using A2L |
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Step 3. Beat note detection |
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action |
description |
status |
notes |
3-A |
finalize the setup at PSL table |
Electronics, cables and etc.,.. |
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we need some dedicated power cables |
3-B |
alignment of optics at PSL table |
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3-C |
temperature tuning of the lasers |
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3-D |
check frequency counter |
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3-E |
phase lock the VCO |
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Step 4. Digital control to stabilize the PSL |
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action |
description |
status |
notes |
4-A |
connect VCO signal to ADC |
c1ioo or c1lsc |
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4-B |
connect some monitor signals to ADC |
green refl, trans, ..etc., |
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4-B |
simulink model refinement |
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4-C |
DAQ setting |
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4-D |
add RFM for feedingback to MC2 |
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4-E |
medm screen |
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Step 5. measurement |
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action |
description |
status |
notes |
5-A |
cavity scan |
adding offsets onto MC2 feedback |
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5-B |
measure the stability of beat note and IR PDH |
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5-C |
perform the same measurement while X arm is locked to IR |
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what is the dominant noise source |