| ID |
Date |
Author |
Status |
Type |
Category |
Location |
Title |
|
24
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Fri Mar 29 18:33:15 2019 |
Ronic Chiche | Fixed | issue | mechanics | lasers and optics | Optical room | Alignment procedure |
we did again the complete alignment procedure starting with iris and optimizing injection motors Ma and Mb, then installing mirror S2, S3, P4 and P1, optimizing thetaX and thetaY axis for each motor.
everything was fine until we installed P1. we tried to optimize thetaX and thetaY of P1 and we clearly observed a strange motion when doing that :
- for thetaX axis, steps in one direction seem to have a different length from steps in reverse direction.
- for thetaY axis, trying to move in one direction, makes sometime a motion in the reverse direction.
at this moment, it is difficult to say if the problem comes from the controller, the mirror mount or the motor itself.
if both axis are concerned on the same mirror (P1), maybe the problem comes from the mount... to be continued on Monday.
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25
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Tue Apr 2 17:59:18 2019 |
Loïc Amoudry | Fixed | report | lasers and optics | Optical room | Finesse after removing wires |
19/04/01: We removed the wires from the beam path in the cavity. Finesse stayed at 3400. FSR: 33.342 MHz.
When locked:
Input Power: ~4mW
Through S2: ~0.950uW
Through S3: ~0.930uW
Through P4: ~0.850uW |
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26
|
Tue Apr 2 18:03:31 2019 |
Loïc Amoudry | Fixed | report | lasers and optics | Optical room | Transmission of the mirrors |
We openned the cavity, removed S2 and measured trans of P1 and same for S2.
Pin ~= 3.91 mW
PS2 ~= 20 nW --> ~~ 5 ppm !!!
PP1 ~= 5.23 uW --> ~~ 1337 ppm !?!?!
P1 is the Sapphire mirror. 3mm thick. Tomorrow we'll measure its trans again, being out of the mount for constraint issues. |
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27
|
Tue Apr 2 18:05:46 2019 |
Loïc Amoudry | Fixed | info | lasers and optics | Optical room | Beam size at closest spherical mirrors position |
S3 and S2 @ +1 640 000 and P1 and P4 @ -825 000
Diameter in x: 4.7mm
Diameter in y: 4.7mm |
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28
|
Thu Apr 4 09:42:12 2019 |
Loïc Amoudry | Fixed | report | lasers and optics | Optical room | Transmission of the mirrors |
After verification, transmission of P1 correspond to ~150ppm.
The 1337ppm come from a beam leakage. Reflection from P1 goes to the input window which reflects again a part of the beam directly into the cavity between P1 and S3 then between P4 and S2.
| Loïc Amoudry wrote: |
|
We openned the cavity, removed S2 and measured trans of P1 and same for S2.
Pin ~= 3.91 mW
PS2 ~= 20 nW --> ~~ 5 ppm !!!
PP1 ~= 5.23 uW --> ~~ 1337 ppm !?!?!
P1 is the Sapphire mirror. 3mm thick. Tomorrow we'll measure its trans again, being out of the mount for constraint issues.
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29
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Fri Apr 5 11:18:47 2019 |
Loïc Amoudry | Fixed | report | lasers and optics | Optical room | Transmission of the mirrors |
P1 transmission out of the mount (means angle of the mirror is not the real angle):
Pin = 3.2 mW
Pout = 545 nW
Offset = 68 nW
Transmission = (545-68)/3.2e6 = 149 ppm
| Loïc Amoudry wrote: |
|
After verification, transmission of P1 correspond to ~150ppm.
The 1337ppm come from a beam leakage. Reflection from P1 goes to the input window which reflects again a part of the beam directly into the cavity between P1 and S3 then between P4 and S2.
| Loïc Amoudry wrote: |
|
We openned the cavity, removed S2 and measured trans of P1 and same for S2.
Pin ~= 3.91 mW
PS2 ~= 20 nW --> ~~ 5 ppm !!!
PP1 ~= 5.23 uW --> ~~ 1337 ppm !?!?!
P1 is the Sapphire mirror. 3mm thick. Tomorrow we'll measure its trans again, being out of the mount for constraint issues.
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30
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Fri Apr 5 11:28:39 2019 |
Loïc Amoudry | Fixed | report | lasers and optics | Optical room | Finesse with P1 SUPRASIL |
P1 SUPRASIL has been installed instead of P1 Sapphire. It has been cleaned 3 times on each face with wipe+isopropanol before to be installed.
Finesse ~= 10 000 - 11 000 (EOM Sweep of 100 kHz in 10sec, see last image.)
Coupling ~= 45%
Motors position:
P1 = -825 000
S2 = +825 000
S3 = +825 000
P4 = -825 000 |
| Attachment 1: 190404_mode_size_with_P1_SUPRASIL.PNG
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| Attachment 2: 190404_mode_fit_with_P1_SUPRASIL.PNG
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| Attachment 3: tek00000.png
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| Attachment 4: tek00002.png
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31
|
Mon Apr 8 10:18:31 2019 |
Loïc Amoudry | Fixed | report | lasers and optics | Optical room | Finesse after 2days |
Finesse measured this morning after P1 SUPRASIL being into the cavity for two days. In order to check if it's getting dirty.
Finesse still ~= 11 000 |
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32
|
Mon Apr 8 11:55:40 2019 |
Loïc Amoudry | Fixed | report | lasers and optics | Optical room | P4 cleaned and finesse measurement |
P4 cleaned with isopropanol.
Finesse measured afterward: ~=13 000 (clear increase) |
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33
|
Wed Apr 10 13:11:46 2019 |
Loïc Amoudry | Fixed | report | lasers and optics | Optical room | Mirror's cleaning and finesse |
Summary of what have been cleaned the last week:
P1 with isopropanol, finesse 11000
P4 with isopropanol, finesse 13000
S2 with isopropanol, finesse 13000
S3 with isopropanol, finesse 14000
S2 with isopropanol, finesse 14000
P4 with isopropanol, finesse 12500
P4 with isopropanol, finesse 12500
Finesse decreased with last steps which probably means our cleaning technique is at its maximum. We will probably try a cavity axis change with the mirror's motors to increase the finesse to the maximum like that.
Next step is to clean P1 with acetone + pur ethanol, then install the Onefive. |
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34
|
Thu Apr 18 16:07:23 2019 |
Loïc Amoudry | Fixed | info | lasers and optics | Optical room | Injection of 33MHz Onefive through fiber |
Output power of the Onefive, and power after injection and different components have been measured.
Coupling ~= 90%
Each of our two EOM roughly have the same loses ~3dB |
| Attachment 1: power_ouput_Onefive.PNG
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| Attachment 2: power_after_injection_and_point9dB_blue_fiber.PNG
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| Attachment 3: power_after_halfwaveplate_and_injection_and_point9dB_blue_fiber.PNG
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| Attachment 4: power_after_halfwaveplate_and_injection_and_point9dB_blue_fiber_and_EOM_NIR-MPX-LN-0dot1.PNG
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| Attachment 5: power_after_halfwaveplate_and_injection_and_point9dB_blue_fiber_and_EOM_NIR-MPX-LN-02.PNG
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35
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Thu Apr 18 16:17:53 2019 |
Loïc Amoudry | Fixed | issue | lasers and optics | Optical room | 33MHz Onefive power overtime decrease |
Power of the 33MHz Onfive decreases over time. Have to pay attention to that.
Note that air dryers have never been stopped.
10th april 2018: ~40mW (first picture, 10dB filter)
25th september 2018: ~36mW (second picture, 10dB filter)
16th april 2019: ~29mW (third picture, no filter)
|
| Attachment 1: 180410_power_33mhz_1jours.PNG
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| Attachment 2: 180925_Power.JPG
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| Attachment 3: 190416_power_ouput_Onefive.PNG
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36
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Tue May 21 17:44:46 2019 |
Loïc Amoudry | Fixed | report | lasers and optics | Optical room | New Suprasil mirror from LMA |
14/05/19:
New Suprasil mirror received. It will replace the S-BOX suprasil mirror on ThomX which was already replacing the sapphire mirror.
First finesse measurement: 14000
Features sent by Christophe Michel:
"- Transmission mesurée (1064 nm)= 172 ppm ; Transmission estimée (1031 nm)= 140 ppm
- Réflexion (1064 nm)= 1025 ppm; doit être inférieure à 1031 nm
L'AR n'est pas bon alors que l'on obtenu 170 ppm pour le run de calage!
J'espère que vous pourrez néanmoins l'utiliser.
- Diffusion moyenne sur diamètre 12 mm: 2.6 ppm"
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37
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Tue May 21 17:49:30 2019 |
Loïc Amoudry | Fixed | report | lasers and optics | Optical room | Finesse after cleaning (new suprasil mirror) |
15/05/19-20/05/19:
Cleaning of the mirrors:
Initial finesse 14000 @air
S2 with isopropanol, finesse 17000 @air
P4 with isopropanol, finesse 17000 @air
S3 with isopropanol, finesse 17000 @air
S3 with first contact, finesse 17000 @air
S2 with first contact, finesse 17000 @air |
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38
|
Thu May 23 10:10:56 2019 |
Ronic Chiche | Fixed | report | lasers and optics | Optical room | Finesse measurement by decay time technique |
5 Files attached:
- Note on the technique and results for the present cavity on 2019, May 21th : F ~ 18 000
- 2Tektronix scope raw data
- 2 matlab files to fit the scope raw data and extract the Finesse |
| Attachment 1: 2019-05-21_-_Finesse_measurement_by_decay_time_technique.docx
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| Attachment 2: tek0005CH1.isf
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| Attachment 3: tek0006CH1.isf
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| Attachment 4: plotdata.m
|
clear
clc
global datacut tcut Trt
[h,data]=myisfread('tek0005CH1.isf');
dt=h.Xincr;
Nt=h.Npoints;
t=0:dt:(Nt-1)*dt;
t=t';
% offset removing
offset=mean(data(0.9*Nt:Nt));
data=data-offset;
% magnitude calculation
datamax=mean(data(1:0.1*Nt));
% cuting data to remove constant part at the beginning of the signal
% and where log(data) becomes complex (signal close to zero is sometime negative)
id1=find(data<0.967*datamax);
id2=find(imag(log(data))~=0);
tcut=t(id1(1):id2(1)-1);
datacut=data(id1(1):id2(1)-1);
%fit
L=9;
c=3e8;
Trt=L/c;
rho=1-1.5e-4;
k=1-15e-4;
pc0=0.14;
t0=2e-3;
x0=[rho k pc0 t0];
options = optimset('Display','iter','PlotFcns',@optimplotfval,'TolX',1e-7,'TolFun',1e-7);
x=fminsearch('myerror',x0,options);
rho=x(1);
k=x(2);
pc0=x(3);
t0=x(4);
datafit=pc0/(rho-k)^2*((1-k)*rho.^((tcut-t0)/Trt)-(1-rho)*k.^((tcut-t0)/Trt)).^2;
%%
figure(1)
clf
plot(t*1e3,data)
grid on
xlabel('Time (ms)')
ylabel('Transmited power (A.U)')
figure(2)
clf
plot(tcut*1e3,log(datacut))
hold on
plot(tcut*1e3,log(datafit),'.')
grid on
xlabel('Time (ms)')
ylabel('Log(Transmited power) (A.U)')
legend('data','fit')
Tpin=Trt/2/abs(log(k));
Tcav=Trt/2/abs(log(rho));
F=2*pi*Tcav/Trt;
disp(['Finesse : ' num2str(F)])
disp(['Cavity decay time : ' num2str(Tcav*1e6) ' µs'])
disp(['Pin sw decay time : ' num2str(Tpin*1e6) ' µs'])
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| Attachment 5: myerror.m
|
function [ output ] = myerror( x )
%MYERROR Summary of this function goes here
% Detailed explanation goes here
global tcut datacut Trt
rho=x(1);
k=x(2);
pc0=x(3);
t0=x(4);
mydata=pc0/(rho-k)^2*((1-k)*rho.^((tcut-t0)/Trt)-(1-rho)*k.^((tcut-t0)/Trt)).^2;
output=sum((mydata-datacut).^2);
end
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39
|
Thu May 23 17:30:03 2019 |
Loïc Amoudry | Fixed | report | lasers and optics | Optical room | Transmission of Sapphire mirror |
See image. |
| Attachment 1: Sapphire_transmission.PNG
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42
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Wed Jun 12 17:49:20 2019 |
Loïc Amoudry | Fixed | info | lasers and optics | Optical room | Polarization |
Polariztion measured with Input vertically/horizontally polarized (~100% DOLP)
- Transmission (P4) locked on cavity horizontal polarization is ~50% linearly polarized and ~50% unpolarized ?
- Transmission (P4) locked on cavity vertical polarization is ~50% linearly polarized and ~50% unpolarized ? |
| Attachment 1: Polar_horiz_trans_P4.PNG
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| Attachment 2: Polar_vert_trans_P4.PNG
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| Attachment 3: Polar_vert_input.PNG
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43
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Tue Jun 18 20:44:34 2019 |
Huan Wang | Fixed | info | lasers and optics | Optical room | telescope for Koheras |
telescope of Koheras is removed, information record here:
- distance between collimator edge and -50 lens mount edge is 14.7cm,
- distance between another edge of -50 lens mount and +250 lens mount edge is 14.3cm,
- distance between another edge of +250 lens mount and edge of bread board is 25cm. |
| Attachment 1: 2019.06.18_telescope_of_Koheras.jpg
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46
|
Thu Jul 4 10:17:46 2019 |
Ronic Chiche | Fixed | info | detectors and electronics | Optical room | New design for PDH boxes |
A new design has been studied for the 5 PDH boxes to better match the low (33MHz) repetition rate of the ThomX laser.
the 5 PDH boxes have been modified and tested (see the attached report).
A mixer has been integrated to the PDH box for a more simple use.
the PDH N°1 has been lend to Huan for her experiment in China. |
| Attachment 1: 2019-06-14_-_PDH_Maurice_modifié.pdf
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47
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Thu Jul 4 18:28:55 2019 |
Loïc Amoudry | Fixed | issue | lasers and optics | Optical room | Onefive 33MHz unmodelocked |
Oscillator randomly unmodelocked on 3rd july afternoon (during oscillator power measurement, maybe a reflection from the powermeter power filter ?)
Modelocked this afternoon by putting Onefive motor and phase at reference on the PTC software. |