Install 2-mirror cavity, posted by Xinyi Lu at Optical room about lasers and optics 
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Today Viktor and I completed the installation of the two-mirror cavity and managed to lock and measure the finesse.
- The finesse is 36k now (see figure 1). For the designed value of the mirror, the expected finesse is ~50k.
- The diameter of M2 transmission is 1.67 mm,1.65 mm (see figure 2). |
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Injection at the amplifier current of 2 A, posted by Xinyi Lu at Optical room about lasers and optics
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Today, Ronic and I optimized the locking at the amplifier current of 2 A and obtained ~ 21 kW inside the cavity.
- When all the iris open, the injected power is 10 W and the coupling is ~ 40%, corresponding to an effective gain of 2,100 and
a full gain of 5,250. But the coupling may not be the true value because there is a large spot around the output beam. |
Impacts on mirror's surface, posted by Loïc Amoudry at Optical room about lasers and optics
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All the mirrors show impacts on there surface (some of them do not show deposit). Does it come from experiments or fabrication ? Are these holes
or bumps ? |
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Images of ThomX mirrors , posted by Manar Amer at Optical room about lasers and optics
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Under the microscope,
the spherical mirrors show the deposit of metal dots on the reflecting surface and not on the back of the mirrors
The mirror with fewer spots near the center was used in the setup. |
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Images of ThomX mirrors , posted by Manar Amer at Optical room about lasers and optics
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Mirror images in the previous log showing the metal deposit of the coating of the spherical mirrors
(not sent by mail due to large size of images)
Manar |
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High power experiments (550kW), posted by Xinyi Lu at Optical room about lasers and optics
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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) |
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High power experiments (520kW), posted by Xinyi Lu at Optical room about lasers and optics
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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 |
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High power experiments (500kW), posted by Xinyi Lu at Optical room about lasers and optics
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Last week, we achieved a stable intracavity average power of 500kW, limited by amplifier power. The experimental data are shown in Figure 1.
- We measured the transmitted laser with a power meter in the windows behind M2 and M4 respectively, and the results were consistent, so the
measurements were credible. |
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High power experiments (272kW), posted by Xinyi Lu at Optical room about lasers and optics
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Today, Ronic and I achieved 272kW inside the cavity at 7.5A. The coupling maintained 60%-70%.
Amp current (A)
Injection power (W)
Circulating power (kW)
Gain
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High power experiments (200kW), posted by Xinyi Lu at Optical room about lasers and optics
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These days, Ronic and I achieved 200kW inside the cavity and 70% coupling efficiency.
- By optimizing the telescope, the coupling reached 70% with iris fully open and maintained 60%-70% coupling at high power.
- The cavity mode went from 2.2mm,2.5mm (38kW) to finally 2.3mm,2.8mm (200kW) without changing a lot. |
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High power experiments (200kW), posted by Xinyi Lu at Optical room about lasers and optics
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all the injection power in the chart have not been measured recently but during the Loic thesis period.
and these old measurements stopped at 5.5A of pump current.... so, the data at "8A" is a pure estimation.
about the last measurement : |
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Glow discharge cleaner on SBOX mirrors, posted by Loïc Amoudry at Optical room about lasers and optics
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The glow discharge cleaner has been tested on the SBOX mirrors.
I've put them 1 by 1. Each run was 15min long at 15mA. The mirrors HR face was always away from the electrode and ~35° angle
with the support. These values have been choosen thanks to the reference: |
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Fundamental Mode TEM00, posted by Manar Amer at Optical room about lasers and optics
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The current setup for the SBox has a beam viewer and 2 photodiodes placed at reflection and transmission.
The CW laser piezoelectric crystal was driven using the lase lock system to observe the 00 mode.
Mode Observed and has no reflection (from what was previously seen) |
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Fundamental Mode TEM00, posted by Manar Amer at Optical room about lasers and optics
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Adding images from the transmission after the spherical mirrors M3 and M4 window for a resonating mode inside the cavity.
There appears to be some misalignment from the center of the mirror ???
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Fundamental Mode TEM00, posted by Manar Amer at Optical room about lasers and optics
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Images of the Transmitted beam at M2 mirror at different days.
The first one was from last week, the second from yesterday.
There is misalignment (drift due to temperature) from the position where the beam was initially. ( reference taken between centers of mode and |
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Fundamental Mode TEM00, posted by Manar Amer at Optical room about lasers and optics
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Closing series of 00 mode for FSR @ 133.33 MHz
Manar |
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First run with spare mirrors, posted by Loïc Amoudry at Optical room about lasers and optics
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I (A)
Trans (mW)
Coupling (%)
Pin
(W)
Gain
0
4
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Finesse vs power by difference between main and second resonance, posted by Loïc Amoudry at Optical room about lasers and optics
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Measurements show that ratio decrease versus power. BUT, the second resonance measurement induce lower power in the cavity so the ratio is not directly
true.
Also, simulation of the main/second resonance power by Pierre's simulation has shown ratio ~50, ~47.6 and 43.5 respectively for 0A, 2A and |
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Finesse vs power by difference between main and second resonance, posted by Loïc Amoudry at Optical room about lasers and optics
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Measurement on 24/10/18
Loïc
Amoudry wrote:
Measurements show that ratio decrease versus power. BUT, the second |
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Finesse vs power by difference between main and second resonance, posted by Loïc Amoudry at Optical room about lasers and optics
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Measurement on 25/10/2018
Loïc
Amoudry wrote:
Measurements show that ratio decrease versus power. BUT, the second |