FSR change & Finesse Measurements , posted by Manar Amer at Optical room about lasers and optics | detectors and electronics
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a Finesse of 30k with the present mirrors :
T1=120 ppm ;A1=(2.6+1) ppm;
T2=1.5 ppm ;A2=(4.5+0.27) ppm;
corresponds to 39 ppm of additional losses for each mirror and a theoretical gain of about 11k.
| Manar Amer wrote: |
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Yesterday evening the cavity was Vacuum pumped up to pressure of 5.5*10^-2 and locked
changed FSR to be 216.662 MHz and alignment a little and measured the Finesse
in Vacuum we have average Finesse = 30341.6265
FWHM (KHz) = 7.0592
Finesse = 30692.1961
FWHM (KHz) = 7.2186
Finesse = 30014.556
FWHM (KHz) = 7.1051
Finesse = 30493.7635
FWHM (KHz) = 7.1079
Finesse = 30481.9812
FWHM (KHz) = 7.1413
Finesse = 30339.2695
FWHM (KHz) = 7.1624
Finesse = 30249.776
FWHM (KHz) = 7.0239
Finesse = 30846.2719
FWHM (KHz) = 7.2614
Finesse = 29837.6477
FWHM (KHz) = 7.1935
Finesse = 30119.1768
| Manar Amer wrote: |
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The FSR of the 2 mirror (plan-spherical) Cavity was adjusted from 210 MHz to reach 216.643 MHz
it was done by having two reference irises, one at the injection point and one at the reflection
then changing the position of injection plan mirror to slightly closer distance and monitoring the reflection on the oscilloscope to be max.
The cavity modes were still seen, and we had to only improve the injection alignment after.
Me and Ronic locked in air and measured the Finesse, which was bigger by ~ 20%
average Finesse = 30208.53614
FWHM (KHz) = 7.0179
Finesse = 30869.9522
FWHM (KHz) = 7.1257
Finesse = 30403.005
FWHM (KHz) = 7.1287
Finesse = 30390.4014
FWHM (KHz) = 7.2884
Finesse = 29724.5531
FWHM (KHz) = 7.3055
Finesse = 29654.769
| Manar Amer wrote: |
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Update for Finesse measurement, The cavity was put under vacuum ~ 1.1*10^-1 mbar
and the alignment and coupling improved.
FSR = 210.1 MHz
Average Finesse = 25686.46222
FWHM (KHz) = 8.2387
Finesse = 25501.5659
FWHM (KHz) = 8.2028
Finesse = 25613.2858
FWHM (KHz) = 8.0978
Finesse = 25945.3289
FWHM (KHz) = 8.1744
Finesse = 25702.3142
FWHM (KHz) = 8.1847
Finesse = 25669.8163
Concluded from Ronic's calculations, this could be the maximum finesse we might be able to obtain with this setup
with Gain ~ 8000
On Monday we adjust the frequency to match 2160.66 MHz and lock the Pulsed,
at the same time start we start with the CELIA amplifier.
| Manar Amer wrote: |
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The cavity was realigned using irises instead of pinholes, gave a better alignment.
The inside of the box, the spherical and the injection mirror were cleaned and placed back inside the box.
we see beating of fundamental mode, previously at the transmission point we placed a wedge to split the beam which resulted in an elliptical mode
we removed it and placed a very thin beam splitter, the beam is circular now.
The cavity was locked in air at a coupling of ~ 60-70 %
Finesse and line width measured five readings with a Finesse average 25095.08884 of a Gain ~ 8000
FWHM (KHz) = 8.2928
Finesse = 25323.0544
FWHM (KHz) = 7.9202
Finesse = 26514.4395
FWHM (KHz) = 8.5834
Finesse = 24465.8636
FWHM (KHz) = 8.4571
Finesse = 24831.2419
FWHM (KHz) = 8.6275
Finesse = 24340.8448
Theoretical and expected Finesse for the 2 mirror setup with the losses is calculated by Ronic for comparison between four and 2 mirror setup.
| Manar Amer wrote: |
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The SBox cavity setup was changed to have only 2 mirrors M1 plane and M2 spherical, both from ThomX
Distance between the mirror ~ 72 cm , increased from 70 cm to take into account the thickness of the ThomX mirrors
Two lenses (300 mm @ 50 cm , 200 @ 104 cm) were placed to have the beam radius ~ 0.55 mm.
The cavity was locked with a coupling of 60 %, for Finesse measurement the sweep was taken over 100 KHz of 2 seconds.
FSR ~ 210.00 MHz, line width ~ 8.56 KHz, Finesse ~ 24 500 .
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FSR and Finesse measurement, posted by Ronic Chiche at Optical room about lasers and optics 
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Yesterday the cavity has been aligned and locked with the CW Koheras laser.
the FSR has been measured by modulation technique at 133.344MHz at 1mbar pressure in the cavity.
the polarization has to be optimized for the Finesse measurement otherwise, some "shoulders" appear beside the Airy peak and reduce Finesse fit.
once it is done, 3 consecutive measurements give an average Finesse of 20800. |
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FSR and Finesse measurement, posted by Xinyi Lu at Optical room about lasers and optics
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- Today, Ronic and I measured the finesse and FSR after optimizing the locking. FSR was adjusted to 160.27 MHz to match the pulsed laser repetition rate. The finesse was 3029.
Note: It's now CW laser injected, SBOX's old mirrors. There are lots of dust on the old mirrors without cleaning.
- Then we cleaned the cavity inside and outside, and removed four mirrors.
- Tomorrow we will check the clean condition and install new mirrors if we can. Before installation, it may be helpful to discuss how to minimize the introduction of dust. |
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Dust Cleaning of SBox, posted by Manar Amer at Optical room about utilities
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An Initial cleaning of the KBoX outside was done, All the optics and mechanics placed that were on the table were removed.
Only the old Mitylaser amplifier remains on the table.
Since we will be using the ThomX Celia amplifier, we will remove it and place it in a secure location (to be decided).
Tomorrow a cleaning of the inside of the cavity box is to be done. |
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Dust Cleaning of SBox, posted by Manar Amer at Optical room about utilities
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The cleaning was done twice with half an hour interval between the two times
reading on the dust meter was taken after each time, and it was zero averaged over a 10-min
| Manar Amer wrote: |
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An Initial cleaning of the KBoX outside was done, All the optics and mechanics placed that were on the table were removed.
Only the old Mitylaser amplifier remains on the table.
Since we will be using the ThomX Celia amplifier, we will remove it and place it in a secure location (to be decided).
Tomorrow a cleaning of the inside of the cavity box is to be done.
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Dust Cleaning of SBox, posted by Manar Amer at Optical room about mechanics | lasers and optics | utilities 6x
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The inside of the cavity was cleaned today. It was very dirty and had big dust particles and fibers inside.
Cleaning was done for everything; wall, floor, fixed mounts, wires (still have some dust difficult to remove), edges.
The dust meter average was measured outside the cavity (2471 p/m3 av 6 min) and inside after cleaning (1424 p/m3 av 10 min).
The cavity was left open under the clean air flow, will observe it under UV, clean and measure Dust tomorrow.
Images attached are after cleaning.
Objects inside the cavity at the moment :
- 4 main mirror mounts
- 4 mirror fixers on mounts and 3 screws each (total 12)
- 2 reflecting mirror mounts
- 2 dielectric mirrors (mounted and to be cleaned)
- two mounts for D-shaped mirrors.
- 2 D-shaped mirrors (unmounted, and they will need cleaning)
- 2 metal irises (pinholes)
| Manar Amer wrote: |
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The cleaning was done twice with half an hour interval between the two times
reading on the dust meter was taken after each time, and it was zero averaged over a 10-min
| Manar Amer wrote: |
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An Initial cleaning of the KBoX outside was done, All the optics and mechanics placed that were on the table were removed.
Only the old Mitylaser amplifier remains on the table.
Since we will be using the ThomX Celia amplifier, we will remove it and place it in a secure location (to be decided).
Tomorrow a cleaning of the inside of the cavity box is to be done.
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Dust Cleaning of SBox, posted by Manar Amer at Optical room about mechanics | lasers and optics | utilities
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After an overnight where the cavity box was left open, a measurement of the Dust meter was taken:
Outside on the optical table on direct air flux (1701 p/m3 Av 10 min) and
Inside the cavity box (998 p/m3 Av 10 min)
The dust inside the cavity has decreased by ~ 30 % for 0.3 u particles.
Note: the cavity box is still open.
| Manar Amer wrote: |
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The inside of the cavity was cleaned today. It was very dirty and had big dust particles and fibers inside.
Cleaning was done for everything; wall, floor, fixed mounts, wires (still have some dust difficult to remove), edges.
The dust meter average was measured outside the cavity (2471 p/m3 av 6 min) and inside after cleaning (1424 p/m3 av 10 min).
The cavity was left open under the clean air flow, will observe it under UV, clean and measure Dust tomorrow.
Images attached are after cleaning.
Objects inside the cavity at the moment :
- 4 main mirror mounts
- 4 mirror fixers on mounts and 3 screws each (total 12)
- 2 reflecting mirror mounts
- 2 dielectric mirrors (mounted and to be cleaned)
- two mounts for D-shaped mirrors.
- 2 D-shaped mirrors (unmounted, and they will need cleaning)
- 2 metal irises (pinholes)
| Manar Amer wrote: |
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The cleaning was done twice with half an hour interval between the two times
reading on the dust meter was taken after each time, and it was zero averaged over a 10-min
| Manar Amer wrote: |
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An Initial cleaning of the KBoX outside was done, All the optics and mechanics placed that were on the table were removed.
Only the old Mitylaser amplifier remains on the table.
Since we will be using the ThomX Celia amplifier, we will remove it and place it in a secure location (to be decided).
Tomorrow a cleaning of the inside of the cavity box is to be done.
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Divergence of the CW beam after collimator , posted by Manar Amer at Optical room about lasers and optics
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Closing the series of the telescope for the beam @ 133.33 MHz
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Different cavity modes & Pulse width, posted by Xinyi Lu at Optical room about lasers and optics
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- Last week, we obtained three curves of the variation of different cavity modes with power (Fig. 1). By comparing the gain for similar cavity mode sizes, we found that the gain always drops with increasing power.
- We measured the pulse width. The pulse width of the seed laser, after CVBG, amplified at 2A was measured by UPD (rise time < 70ps). Code filtering was performed by comparing the data to reduce the effect of rise time. The final result was t= 186 ps after CVBG and t=162 ps for the amplified at 2A.
- Today we will measure finesse using CW laser.
| Xinyi Lu wrote: |
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- We re-measured the gain before moving the mirror. Gain ~9000 was achieved at 3A, but as the power increased, the gain dropped and was difficult to optimize. In fact, we found that each day the gain was a little higher than the previous day.
| Amp current (A) |
Injection power (W) |
Circulating power (kW) |
Gain(coupling~0.7) |
Finesse |
| 3 |
23.5 |
213 |
9046 |
33595 |
| 4 |
35.5 |
309 |
8692 |
32933 |
| 5 |
47 |
390 |
8292 |
32165 |
- We then moved the M3 spherical mirror 1.7mm to make the beam size larger and measured the variation in cavity mode size at different powers. (Figure 1, red is the original result and blue is the result for a larger cavity mode). It is clear that the larger the cavity mode, the larger the slope. The new slope of w_y is 7.9mm/MW. Tomorrow we will make the cavity mode smaller (like in Carstens' paper) and compare the three curves.
- It is not simple to compare the gain variations of different cavity modes because it takes more time to optimize the telescope and alignment. Ronic suggested that we could compensate for the cavity mode variation by moving the spherical mirror to see how the gain changes at different powers while keeping the cavity mode unchanged.
- In addition, we measured the spectrum of the menhir laser, after cvgb, amplifier output at 3A (Figure 2). We found that the peak changed from 1031 nm to 1032 nm after CVBG, probably because of the imperfect alignment of CVBG.
| Xinyi Lu wrote: |
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- Today we moved the position of the D-shaped mirror at 6A. When motor1 (vertical) is 0.2mm away from the spot, the power in the cavity rises from 457kW to 483kW. Gain=8407 is similar to that at low power (Gain=8511). So the D-shaped mirror lost some of the gain in the previous experiments. At 4A and 5A we did not move the D-shaped mirror. (Figure 1)
- At 8A, we got 553 kW inside the cavity for one minute (Figure 2). The pump temperature is higher than yesterday (up to 34°C).
- At 7.5A and 8A, the cavity can remain stably locked, but the power fluctuation in the cavity is so large that it is difficult to optimize the alignment. This may be due to the short time the amplifier was on, the pump temperature, amplifier pointing and power fluctuations, and thermal effects in the cavity....... The amplifier operated differently at different moments.
- We measured the spectrum of the amplified laser. (Figure 3) The peak is 1032.2 nm. We will optimize the alignment and increase the power to optimize this measurement.
- Next arrangement
Thursday: larger laser beam size
Friday: smaller laser beam size
Monday: finesse measurement with CW laser (Firstly check the possibility of measuring with pulsed laser)
| Xinyi Lu wrote: |
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Yesterday, Ronic, Xing, Qili and I achieved a more stable 520kW power at 7.5A (71W injection) by optimizing the alignment and locking parameters. (Figure 1)
- The cavity can be stable locked when airflow is on. At 7.5A, the pump temperature is about 28℃. The chiller temperature didn't change, to the same 23 ℃ setting. We can try 8A later (75W injection) for a short time;
- Figure 2 demonstrates the cavity mode variation, wy/Pc ~ 1.7 mm/MW, half that of the OL paper (3.3 mm/MW). The thermal deformation of our device is much smaller.
- The experimental data are shown in Figure 3. Figure 4 shows the injection power vs circulating power.
- There are some tests that can be done at the moment. I'll update on the elog after discussing the necessity today. ^_^
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Different cavity modes & Pulse width, posted by Xinyi Lu at Optical room about lasers and optics
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Additional information:
The pulse duration has been performed in RF on a UPD-70-IR2-P photodiode from Alphalas GmbH by carefully deconvoluting the response function of the photodiode measured directly with the sub-picosecond laser beam.
Figure 1 shows the pulse width through the CVBG. Figure 2 is the pulse width when amplified to 10W.
| Xinyi Lu wrote: |
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- Last week, we obtained three curves of the variation of different cavity modes with power (Fig. 1). By comparing the gain for similar cavity mode sizes, we found that the gain always drops with increasing power.
- We measured the pulse width. The pulse width of the seed laser, after CVBG, amplified at 2A was measured by UPD (rise time < 70ps). Code filtering was performed by comparing the data to reduce the effect of rise time. The final result was t= 186 ps after CVBG and t=162 ps for the amplified at 2A.
- Today we will measure finesse using CW laser.
| Xinyi Lu wrote: |
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- We re-measured the gain before moving the mirror. Gain ~9000 was achieved at 3A, but as the power increased, the gain dropped and was difficult to optimize. In fact, we found that each day the gain was a little higher than the previous day.
| Amp current (A) |
Injection power (W) |
Circulating power (kW) |
Gain(coupling~0.7) |
Finesse |
| 3 |
23.5 |
213 |
9046 |
33595 |
| 4 |
35.5 |
309 |
8692 |
32933 |
| 5 |
47 |
390 |
8292 |
32165 |
- We then moved the M3 spherical mirror 1.7mm to make the beam size larger and measured the variation in cavity mode size at different powers. (Figure 1, red is the original result and blue is the result for a larger cavity mode). It is clear that the larger the cavity mode, the larger the slope. The new slope of w_y is 7.9mm/MW. Tomorrow we will make the cavity mode smaller (like in Carstens' paper) and compare the three curves.
- It is not simple to compare the gain variations of different cavity modes because it takes more time to optimize the telescope and alignment. Ronic suggested that we could compensate for the cavity mode variation by moving the spherical mirror to see how the gain changes at different powers while keeping the cavity mode unchanged.
- In addition, we measured the spectrum of the menhir laser, after cvgb, amplifier output at 3A (Figure 2). We found that the peak changed from 1031 nm to 1032 nm after CVBG, probably because of the imperfect alignment of CVBG.
| Xinyi Lu wrote: |
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- Today we moved the position of the D-shaped mirror at 6A. When motor1 (vertical) is 0.2mm away from the spot, the power in the cavity rises from 457kW to 483kW. Gain=8407 is similar to that at low power (Gain=8511). So the D-shaped mirror lost some of the gain in the previous experiments. At 4A and 5A we did not move the D-shaped mirror. (Figure 1)
- At 8A, we got 553 kW inside the cavity for one minute (Figure 2). The pump temperature is higher than yesterday (up to 34°C).
- At 7.5A and 8A, the cavity can remain stably locked, but the power fluctuation in the cavity is so large that it is difficult to optimize the alignment. This may be due to the short time the amplifier was on, the pump temperature, amplifier pointing and power fluctuations, and thermal effects in the cavity....... The amplifier operated differently at different moments.
- We measured the spectrum of the amplified laser. (Figure 3) The peak is 1032.2 nm. We will optimize the alignment and increase the power to optimize this measurement.
- Next arrangement
Thursday: larger laser beam size
Friday: smaller laser beam size
Monday: finesse measurement with CW laser (Firstly check the possibility of measuring with pulsed laser)
| Xinyi Lu wrote: |
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Yesterday, Ronic, Xing, Qili and I achieved a more stable 520kW power at 7.5A (71W injection) by optimizing the alignment and locking parameters. (Figure 1)
- The cavity can be stable locked when airflow is on. At 7.5A, the pump temperature is about 28℃. The chiller temperature didn't change, to the same 23 ℃ setting. We can try 8A later (75W injection) for a short time;
- Figure 2 demonstrates the cavity mode variation, wy/Pc ~ 1.7 mm/MW, half that of the OL paper (3.3 mm/MW). The thermal deformation of our device is much smaller.
- The experimental data are shown in Figure 3. Figure 4 shows the injection power vs circulating power.
- There are some tests that can be done at the moment. I'll update on the elog after discussing the necessity today. ^_^
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Deposit on S-box mirrors after return from LMA, posted by Loïc Amoudry at Optical room about lasers and optics
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Cleaning on dirty surface shows something is deposited on the surface. Cleaning displaces and removes part of the deposit. |
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Damaged mirrors test, posted by Alice Renaux at Optical room about lasers and optics
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Today with Dorian we tested three mirrors with which we previously haven't been able to obtain any resonance or optical beating :
- C16111/11 : The mirror looks normal under a microscope, apart from a few inclusions and maybe a small scratch towards the edge. We tested it with a 161186 M1 mirror and we weren't able to obtain any optical beating on the cavity's mirrors or resonance.
- 161185 (1) : The mirror looks normal with the naked eye. We tested it with a 161182 M2 mirror and we were able to notice some optical beating on the cavity's mirrors as well as small resonance peaks and a higher-order transverse mode.
- 161185 (2) : The mirror shows some damage on the substrate side (not the coated side). We tested it with a 161186 M2 mirror and we were able to notice some optical beating on the cavity's mirrors as well as huge resonance peaks and a Gaussian transverse mode.
The updated recap file is available here, as well as a few pictures. |
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Damage on mirror surface , posted by Manar Amer at Optical room about lasers and optics
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Following the storage of ~ 50 kW inside the cavity and a sudden drop in transmitted power from the cavity
damage to the mirror surface was suspected.
We broke vacuum and took images of the surface of the 2 mirrors in the cavity, the spherical and the planar mirror
image 1 , spherical reflective surface (no visible damage with the UV light, and no visible damage under the microscope)
image 2 , planar coupler mirror reflective surface (no visible damage under UV light, but under the microscope there is a damaged spot close to the center)
image 4 is the planar surface reflective surface at zoom 8 on the microscope.
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Damage on mirror surface , posted by Manar Amer at Optical room about lasers and optics
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Tomorrow will try to shift the injection mirror to avoid hitting the damaged spot.
| Manar Amer wrote: |
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Following the storage of ~ 50 kW inside the cavity and a sudden drop in transmitted power from the cavity
damage to the mirror surface was suspected.
We broke vacuum and took images of the surface of the 2 mirrors in the cavity, the spherical and the planar mirror
image 1 , spherical reflective surface (no visible damage with the UV light, and no visible damage under the microscope)
image 2 , planar coupler mirror reflective surface (no visible damage under UV light, but under the microscope there is a damaged spot close to the center)
image 4 is the planar surface reflective surface at zoom 8 on the microscope.
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Damage on mirror surface , posted by Manar Amer at Optical room about lasers and optics
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After discussing, we have decided against shifting the mirror to avoid the time lost.
We changed the injection mirror to a different mirror from Mighty Laser set, Transmission of mirror 80 ppm. (no visible damage at the center of the mirror, only a small scratch on the back)
mirror cleaned using pure ethanol and pure water with spin coater, also the spherical mirror was cleaned again.
| Manar Amer wrote: |
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Tomorrow will try to shift the injection mirror to avoid hitting the damaged spot.
| Manar Amer wrote: |
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Following the storage of ~ 50 kW inside the cavity and a sudden drop in transmitted power from the cavity
damage to the mirror surface was suspected.
We broke vacuum and took images of the surface of the 2 mirrors in the cavity, the spherical and the planar mirror
image 1 , spherical reflective surface (no visible damage with the UV light, and no visible damage under the microscope)
image 2 , planar coupler mirror reflective surface (no visible damage under UV light, but under the microscope there is a damaged spot close to the center)
image 4 is the planar surface reflective surface at zoom 8 on the microscope.
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Damage on mirror surface , posted by Manar Amer at Optical room about lasers and optics
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a better image of the damaged spot, image taken with the arrow for the reflective surface facing the other direction (image shows position)
The image of M1 for ThomX reflective surface was taken at min zoom (full image scale 13 mm) and max zoom (full image scale 2 mm) on microscope
The spot appears to be not close to the center of the mirror, at max zoom in the center we do not see the spot it is just out of the image
the last image has the mirror position adjusted to center the damaged spot for a better image of it.
| Manar Amer wrote: |
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After discussing, we have decided against shifting the mirror to avoid the time lost.
We changed the injection mirror to a different mirror from Mighty Laser set, Transmission of mirror 80 ppm. (no visible damage at the center of the mirror, only a small scratch on the back)
mirror cleaned using pure ethanol and pure water with spin coater, also the spherical mirror was cleaned again.
| Manar Amer wrote: |
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Tomorrow will try to shift the injection mirror to avoid hitting the damaged spot.
| Manar Amer wrote: |
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Following the storage of ~ 50 kW inside the cavity and a sudden drop in transmitted power from the cavity
damage to the mirror surface was suspected.
We broke vacuum and took images of the surface of the 2 mirrors in the cavity, the spherical and the planar mirror
image 1 , spherical reflective surface (no visible damage with the UV light, and no visible damage under the microscope)
image 2 , planar coupler mirror reflective surface (no visible damage under UV light, but under the microscope there is a damaged spot close to the center)
image 4 is the planar surface reflective surface at zoom 8 on the microscope.
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Damage on mirror surface , posted by Manar Amer at Optical room about lasers and optics
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ThomX injection mirror has been cleaned and placed again inside the optical cavity.
This time to avoid the damaged spot I have displaced the mirror mount horizontally to have a distance between center of the beam and the spot ~ 2.5 - 3 mm.
The alignment was affected slightly but recovered by adjusting the mirror mount nobs, (00 mode observed in air)
The cavity was closed is being pumped with vacuum.
To be done: adjust the cavity length and find the resonance, improve the outer alignment, lock the cavity
| Manar Amer wrote: |
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a better image of the damaged spot, image taken with the arrow for the reflective surface facing the other direction (image shows position)
The image of M1 for ThomX reflective surface was taken at min zoom (full image scale 13 mm) and max zoom (full image scale 2 mm) on microscope
The spot appears to be not close to the center of the mirror, at max zoom in the center we do not see the spot it is just out of the image
the last image has the mirror position adjusted to center the damaged spot for a better image of it.
| Manar Amer wrote: |
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After discussing, we have decided against shifting the mirror to avoid the time lost.
We changed the injection mirror to a different mirror from Mighty Laser set, Transmission of mirror 80 ppm. (no visible damage at the center of the mirror, only a small scratch on the back)
mirror cleaned using pure ethanol and pure water with spin coater, also the spherical mirror was cleaned again.
| Manar Amer wrote: |
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Tomorrow will try to shift the injection mirror to avoid hitting the damaged spot.
| Manar Amer wrote: |
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Following the storage of ~ 50 kW inside the cavity and a sudden drop in transmitted power from the cavity
damage to the mirror surface was suspected.
We broke vacuum and took images of the surface of the 2 mirrors in the cavity, the spherical and the planar mirror
image 1 , spherical reflective surface (no visible damage with the UV light, and no visible damage under the microscope)
image 2 , planar coupler mirror reflective surface (no visible damage under UV light, but under the microscope there is a damaged spot close to the center)
image 4 is the planar surface reflective surface at zoom 8 on the microscope.
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D-shape mirrors positionning status, posted by Ronic Chiche at Optical room about mechanics | lasers and optics | detectors and electronics
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This afternoon we opened the cavity and put the D-shape mirrors at their correct place, close to the beam.
we checked the relative position of the mirrors to the beam using the 2nd stage of the amplifier (<1W) and with the sensitive (and cleaned) orange optical card.
with this configuration, we can see very clearly the beam inside the cavity (~ 100µW) and we can check easily if the D-shape mirrors are correctly placed.
the motors used to move the D-shape are the Newport Picomotors 8303-V
with roughly 30nm/step sensitivity and 50mm of range (~1 600 000 steps)
the 4 axis controller used ot move these motors is the Newport 8742.
For both Vertical and Horizontal D-shape mirrors:
* when you do +N steps on the controller, you retract the D-shape mirror from the beam
* when you do -N steps on the controller, you push the D-shape mirror to the beam
the 0 position on the controller corresponds to the D-shape close to the beam.
now, the FP cavity is closed and pumped to go back to vacuum.
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D-shape mirrors positionning status, posted by Ronic Chiche at Optical room about mechanics | lasers and optics | detectors and electronics
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The cavity box is vacuum pumped at 6*10^-2 mbar.
| Ronic Chiche wrote: |
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This afternoon we opened the cavity and put the D-shape mirrors at their correct place, close to the beam.
we checked the relative position of the mirrors to the beam using the 2nd stage of the amplifier (<1W) and with the sensitive (and cleaned) orange optical card.
with this configuration, we can see very clearly the beam inside the cavity (~ 100µW) and we can check easily if the D-shape mirrors are correctly placed.
the motors used to move the D-shape are the Newport Picomotors 8303-V
with roughly 30nm/step sensitivity and 50mm of range (~1 600 000 steps)
the 4 axis controller used ot move these motors is the Newport 8742.
For both Vertical and Horizontal D-shape mirrors:
* when you do +N steps on the controller, you retract the D-shape mirror from the beam
* when you do -N steps on the controller, you push the D-shape mirror to the beam
the 0 position on the controller corresponds to the D-shape close to the beam.
now, the FP cavity is closed and pumped to go back to vacuum.
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D-shape mirrors positionning status, posted by Ronic Chiche at Optical room about mechanics | lasers and optics | detectors and electronics
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summary:
- the motors used to move the D-shape are the Newport Picomotors 8303-V
the sensitivity is roughly 30nm/step
the range is 1 600 000 steps or 50mm
- the 4 axis controller used ot move these motors is the Newport 8742.
channel 1 is for the vertical D-shape
channel 2 is for the horizontal D-shape
+N steps on the controller, you retract the D-shape mirror from the beam
-N steps on the controller, you push the D-shape mirror to the beam
the 0 position, vertically and horizontally is close to the beam.
the stand position is at ~ +200 000 steps in both directions.
| Ronic Chiche wrote: |
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The cavity box is vacuum pumped at 6*10^-2 mbar.
| Ronic Chiche wrote: |
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This afternoon we opened the cavity and put the D-shape mirrors at their correct place, close to the beam.
we checked the relative position of the mirrors to the beam using the 2nd stage of the amplifier (<1W) and with the sensitive (and cleaned) orange optical card.
with this configuration, we can see very clearly the beam inside the cavity (~ 100µW) and we can check easily if the D-shape mirrors are correctly placed.
the motors used to move the D-shape are the Newport Picomotors 8303-V
with roughly 30nm/step sensitivity and 50mm of range (~1 600 000 steps)
the 4 axis controller used ot move these motors is the Newport 8742.
For both Vertical and Horizontal D-shape mirrors:
* when you do +N steps on the controller, you retract the D-shape mirror from the beam
* when you do -N steps on the controller, you push the D-shape mirror to the beam
the 0 position on the controller corresponds to the D-shape close to the beam.
now, the FP cavity is closed and pumped to go back to vacuum.
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