AFM+ InfraRed spectroscopy (IR spectro) has been performed, posted by Loïc Amoudry at Other about lasers and optics 
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AFM+ InfraRed spectroscopy (IR spectro) has been performed on 400kW S-BOX mirrors.
Seems that XPS made M3 and M4 dirty, but M1 have also ome dust. M2 seems clean, further AFM experiment should show that it is as clean as M1. |
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AFM performed on S-BOX mirrors, posted by Loïc Amoudry at Other about lasers and optics
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| 29/02/19 - AFM has shown that spots on mirror's surfaces are bumps and not holes. |
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AFM analysis of M2, posted by Loïc Amoudry at Optical room about lasers and optics
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We had enough time to proceed a quick scan of M2 which has also a hole but not centered on the mirror.
The hole is larger and higher than the one on M1. But the vertical range was to high for the AFM. Then we cannot see if there are sparkles or
not on this image. Further study with microscope would be welcome. |
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AFM analysis of M1, posted by Loïc Amoudry at Optical room about lasers and optics
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AFM has been proceeded on M1 and M2.
The pdf shows the first images taken with the PLIC room Leica microscope (zoom x10 and x80).
Then the hole has been studied with a handmade microscope. It brought a better resolution. We can now see the hole has an edge, a center structure |
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2nd stage amplifier issue, posted by Ronic Chiche at Optical room about lasers and optics
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the 2nd stage amplifier needed several hours (4-5h) to reach its nominal power (we look at photodiode level on a scope), instead of the awaited 30 minutes.
could it come from the probable spectrum shifting of the OneFive laser ?
(the power coming from the CVBG, coupled to the fiber, is lower than expected). |
2nd stage amplifier issue, posted by Ronic Chiche at Optical room about lasers and optics
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Last time, we switched ON directly the 2nd stage at 6A without increasing/decrinsing slowly the current.
today, we switched ON the chiller, switched ON the 1st stage, switch ON the power supply of the 2nd stage at 0A and then we increased slowly the
current until 6A... and the problem disappeared. |
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2nd stage amplifier issue, posted by Ronic Chiche at Optical room about lasers and optics
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2nd stage output power was going down. We checked the pump diode technical data sheet and the operating temperature is [25°C:35°C].
We increased the chiller temperature setpoint from 19°C to 23°C.
Then the output power increased (93mW on 2nd stage photodiode). |
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2nd stage CELIA amplifier, posted by Ronic Chiche at Optical room about lasers and optics
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| today, we measured the 2nd stage CELIA amplifier pump wavelength : 970-990 nm |
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2nd stage CELIA amplifier, posted by Ronic Chiche at Optical room about lasers and optics
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today we did several test with the Dichroic shortpass mirror (Thorlabs DMSP1000) and with a 10nm optical filter around 1030nm (which works in tranmission
at AOI=0).
one used the dichroic mirror in reflection: one should cut the pump @970-990nm and we should keep only the signal @1030nm. |
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2-mirror cavity locking, posted by Alice Renaux at Optical room about lasers and optics
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In June, we encountered some problems regarding the transmission and error signals (see images here),
looking as if the laser was switched off before the cavity was filled.
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2-mirror cavity full setup, posted by Alice Renaux at Optical room about lasers and optics
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Today with Ronic, we changed the FP cavity's mirrors to Layertek (Gamma Factory) mirrors :
- M1 : n°161186 --> fused silica, unknown absorption, unknown diffusion, T1=2500ppm transmission planar mirror ;
- M2 : n°161182 --> fused silica, unknown absorption, unknown diffusion, T2=10ppm transmission, 5m ROC mirror. |
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2-mirror cavity alignment, posted by Alice Renaux at Optical room about mechanics | lasers and optics
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At the beginning of the week, I installed a half-wave plate, a beamsplitter cube and a quarter-wave plate, as well as the end-of-cavity mirror, which
I unsuccessfully tried to align.
I removed the end-of-cavity mirror and started the laser injection over again with the two motorized mirrors placed in front of the vacuum chamber |
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2-mirror cavity alignment, posted by Alice Renaux at Optical room about lasers and optics
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Yesterday and today, I replaced the OEWaves CW laser with the NKT CW laser. Its screen does not display anything, so it has to be operated through the
GraphiK software.
I then re-aligned the cavity with a new adjustment adaptation tool between the mirror mounts and the irises. |
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2-mirror cavity alignment, posted by Alice Renaux at Optical room about lasers and optics
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The NKT laser PZT sensitivity is ~0.09pm/V of wavelength variation, which is equivalent to ~ 25MHz/V
So, the full range of the scan is roughly 250MHz (more than a FSR) for 10V.
It seems impossible to get such large resonances unless the Finesse is very low => let's try to change M1 by a spare GammaFactory plan |
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2 mirror cavity high power experiments, posted by Xinyi Lu at Optical room about lasers and optics
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Today, Ronic and I recorded some intracavity power and cavity mode size as shown in Fig. 1.
Coupling was calculated using the locking curve of this overcoupled cavity. Pr/Pi = 1-Cgeo*Cimp, Cimp = 1-|1-2T1/RTL|^2
We can see that the effective gain, coupling, and mode size decrease with increasing power. And the beam is constantly moving. |
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2 Mirror Setup @ 216.6 MHz, posted by Manar Amer at Optical room about lasers and optics | detectors and electronics
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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. |
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2 Mirror Setup @ 216.6 MHz, posted by Manar Amer at Optical room about lasers and optics | detectors and electronics
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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 |
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2 Mirror Setup @ 216.6 MHz, posted by Manar Amer at Optical room about lasers and optics | detectors and electronics
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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 |
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2 Mirror Setup @ 216.6 MHz, posted by Manar Amer at Optical room about lasers and optics
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Adding information about the 2 mirror cavity setup (plan - spherical) that is currently installed.
From Aurélien at the start of the manipulation.
@ 0 is where the injection mirror is located |
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100W CELIA laser amplifier "how's to" document, posted by Ronic Chiche at Optical room about lasers and optics | software
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1st version of the document.
if some information is not correct or missing, give any comment by replying to this post. |