Record power-up, posted by Loïc Amoudry at Optical room about lasers and optics
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Measurement made on 03/10/18 (nothing has been done since there).
Stable power in the cavity of 225 kW.
| 3rd stage current |
Transmission (mW) |
Pin (W) |
| 0 |
8 |
0.37 |
| 2 |
|
5.3 |
| 2.2 |
145 |
6.4 |
| 3 |
|
10.7 |
| 4 |
350 |
16.1 |
| 5 |
|
21.8 |
| 6 |
|
27.3 |
| 7 |
|
32 |
| 8 |
|
36.7 |
| 8.5 |
640 |
39.1 |
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Polarization optimization, posted by Loïc Amoudry at Optical room about lasers and optics
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Optimization of the polarization has been made the 03/10/18. Checked in reflection of the cavity in reflection&transmission of a PBS, locked and unlocked. Only with 2nd stage.
Ratio values are reflection of PBS divided by transmission or the opposite.
| |
Unlock value |
Ratio min/max |
Lock value |
Ratio min/max |
| No optimization |
|
|
|
|
| Reflection |
1.21 |
X |
3.89 |
X |
| Transmission |
14.3 |
8.5 % |
3.1 |
80 % |
| Only Lambda/2 |
|
|
|
|
| Reflection |
4.4 |
X |
2.91 |
X |
| Transmission |
11 |
40 % |
2.79 |
96 % |
| 2xLambda/2 + 1Lambda/4 |
|
|
|
|
| Reflection |
8.3 |
X |
3.4 |
X |
| Transmission |
6.8 |
82 % |
2.2 |
65 % |
| Same + PID optimization |
|
|
|
|
| Reflection |
9 |
X |
3.35 |
X |
| Transmission |
5.76 |
64 % |
2 |
60 % |
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Phase measurement with HASO, posted by Loïc Amoudry at Optical room about lasers and optics 
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2 measurement.
First one locked, in transmission of M2 with 2nd stage 0A.Total 89 cm from the big waist (planar mirrors). 2 wedges used.
Second one at input beam with the same power. Datas taken at the same equivalent position than the first one. 3 wedges used. |
Phase measurement with HASO, posted by Loïc Amoudry at Optical room about lasers and optics 8x
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* Loic has to fix the number of files (3) regarding the number of measurements (2)
* splitted Intensity and phase HASO files
* image for each file
| Loïc Amoudry wrote: |
|
2 measurement.
First one locked, in transmission of M2 with 2nd stage 0A.Total 89 cm from the big waist (planar mirrors). 2 wedges used.
Second one at input beam with the same power. Datas taken at the same equivalent position than the first one. 3 wedges used.
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Phase measurement with HASO, posted by Loïc Amoudry at Optical room about lasers and optics
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with just intensity, the coupling is 98%, and with phase, x direction coupling is 95%, y direction 97%, so the telescope is good.
| Loïc Amoudry wrote: |
|
* Loic has to fix the number of files (3) regarding the number of measurements (2)
* splitted Intensity and phase HASO files
* image for each file
| Loïc Amoudry wrote: |
|
2 measurement.
First one locked, in transmission of M2 with 2nd stage 0A.Total 89 cm from the big waist (planar mirrors). 2 wedges used.
Second one at input beam with the same power. Datas taken at the same equivalent position than the first one. 3 wedges used.
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Cavity polarization states (Koheras), Finesse of 2 polarization states, posted by Loïc Amoudry at Optical room about lasers and optics
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Measurments of Finesse with the 2 polarization states, let's call them H (higher) and L (lower): 24500 for the H and 23500 for the L.
We checked the polarization states in transmission of the FP cavity after a PBS. The H was stronger in PBS trans and the L stronger in PBS ref.
We measured the power in reflection of the PBS and added a half WP that we aligned with the PBS polarization. Then, to get the maximum power we had to tilt the half WP of 22° for the H and 18° for the L.
Finally we checked the extinction through half WP and PBS for H and L.
- For H : max 75 mW min 5 mW. Ratio 6.66%
- For L : max 70 mW min 4 mW. Ratio 5.7%
Right after Koheras : max 3.5 mW min 47 uW. Ratio 1.3%
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