Download Precision laser metrology for the modern Accelerators Colliders

Precision laser metrology for the modern Accelerators
JINR: V. Batusov, J. Budagov, M. Lyablin, G. Shirkov
CERN: J-Ch. Gayde, B. Di Girolamo, H. Mainaud Durand,
D.Mergelkuhl, M. Nessi, G. Stern
Presented by M. Lyablin
Precision Laser Fiducial line in air
Introduction
 The next generation of linear colliders is very demanding
concerning the alignment tolerances of their components.
For the CLIC project, the reference axis of the components
will have to be pre-aligned within 10 µm at 1 sigma with
respect to a straight line in a sliding window of 200 m
 A new proposal is using a laser beam over 150 m as a
straight alignment reference.
 The method is based on the laser beam space stabilization
effect when a beam propagates in atmospheric air inside a
pipe with standing acoustic wave.
2
Observation of the effect of the stabilization of the laser ray space
location inside the tube with the standing acoustic waves
Demonstration to the CERN delegation
(R.Cashmore at all) of the laser ray
stabilization effect inside the tube.
This photo was made during the
period of high precision laser
controlled assembly in Dubna
of the MODULES of ATLAS TAIL
Hadron Calorimeter.
Our experimental R&D’s have shown that independent of direct
sun rays and of an air heat fluxes we found as a very significance by
an order of magnitude- decrease of the laser beam space noise
oscillation.
We found that the laser beam space uncertainty is strongly decreased upon ray exit
of a tube with the STANDING ACOUSTIC WAVES in an atmospheric air inside.
The left Figure is the σT uncertainty for the “case with the tube“.
The right Figure is the R= σA/ σT ratio with σA for “no tube ” case.
The factor R≈120x gain is an impressive result we observed for 70 m tube.
2,0
σT(μ)
 (m)
т
180
R=σA(μ)/ σT(μ)
1,8
R=В/Т 160
1,6
140
1,4
120
1,2
100
1,0
80
0,8
60
0,6
0,4
40
0,2
20
0,00
10
20
30
40
50
60
70
80
L(m)
0
0
10
20
30
40
50
60
70
80
L(m)
We propose to use as an EXTENDED COORDINATE AXIS the low σT laser
beam obtained on the base of above described new effect.
Laser Fiducial line: operation and design
δ
Ab
Laser
Colimator
QPre
Ae
QPrm
Am
Laser spot
The Laser Fiducial Line (LFL) measuring system uses a laser beam as
the reference of alignment, with its beginning and end points Ab and Ae
determined in the global reference frame of the tunnel.
5
Beginning and end points of the Laser Fiducial Line
Angular positioner
Laser beam
Optical fiber
Support Collimator
Concrete basis
Laser
The fiber-optic input of the laser
radiation into the LFL
Final QPR
Two-axis linear
positioner
Ae
Laser beam
Support
2-axis positioners are needed
for precise alignment
center of the quadrant photodetector
with the laser beam axis
Concrete basis
6
Intermediate points of measurements
Measuring QPR
Space stabilized laser beam
(fiducial line)
Two-axis linear positioners
Plane-parallel plate(PP)
Measured point-O
Measuring station with measurd point-O
Not destroying control system position measured point O
7
Thermal stability of the laser ray position
Tube
Laser beam
We use effect of laser beam
stabilization when it propagates
inside an atmospheric air filled pipe
with standing acoustic waves
Transparent glass
The short term laser ray stabilization scheme
Thermostabilizedair flux
Laser beam
System of short-term
stabilization
Two tubes set was used.
Between tubes the termostabilised
air flux is propagating
Outer tube with a heat insulation
coating
Long term stability system
With allowed few microns for the laser ray displacement from primary direction
the long-term temperature stabilization is to be in the level of 0.5 0C
8
Optimal collimation laser beam
Zmax
Zmax
√2 D0=Dmax
√2 D0
D0
The profile of collimated
laser beam
The telescopic collimator
The laser beam profile with optimal collimation
5500
200
5000
The laser beam optimal propagation length
in function of Laser single-mode beam diameter
Lk (m)
4000
150
Lk(m)
Lenght (m)
The laser beam optimal propagation length
in function of Laser single-mode beam diameter
4500
3500
(A)
(B)
3000
100
2500
2000
1500
50
laser=0.4
laser=0.4
1000
laser=0.63
laser=0.63
500
0
0
0
1
2
3
Laser beam
4
5
6
7
8
9
10
Diameter laser beam (mm)
diameter(mm)
0
5
10
15
20
25
30
35
40
45
50
Diameter laser beam (mm)
The collimation length Lk of single mode laser beam in function
of beam starting diameter: (A) for D by 10mm ;(B) for D by 50 mm
9
Including of the Laser Fiducial Line to the global coordinate system; the LFL
precision control by Total Station in an open air media
The Total Station target with adapter A1
2D – linear positioner
Z’
Т1
Т
A
В1 Laser beamВ2
Laser
Y’
X’
B
Т2
Z
The quadrant photoreceiver QPr1
O
X
Y
with adapterA2
C
D
The measurement stations– global coordinate system
For the 50m laser line an Total Station measurements
the difference was nearly 100μm for 16 meters length
Angular seismic stabilization by the precision INCLINOMETER
The principle of construction of the registration device to measure the seismic
slope of the Earth’s surface.
Laser
Direction
of the reflected beam
after tilt of base
Original
direction of the
reflected beam
QPR
θ
ψ
Cuvette with a liquid
Base
The surface of the liquid
in case of horizontal basis
The surface of the liquid
with tilt base
Main principle : use reflected laser beam from horizontal surface liquid
11
The experimental set-up
50 cm
QPr
CF
L
SM
О1
50 cm
О
•L-laser
•QPr-quadrant photodiode
•O,O1,O2- bases
•SM-semitransparent mirror
•C-calibration screw
•CF- collimator with
changeable focus
Sensor S
C
О2
frequency internal of 10-4Hz÷1Hz
The achieved inclinometer angular precision is 5 10-9 rad
The inclinometer tests
Earthquake In Sibiria 26 February 2011;
6h 17min (World time)
Beginning of earthquake
7h 50min (Geneva time):
26 February 2011
10,5
9,5
9,0
8,5
A
B
8,0
7,7
7,8
7,9
8,0
8,1
8,2
8,3
Geneva time(h)
•The Earth quake in Siberia on February 26, 2011
•Average amplitude of quake in Siberia was 6.5 units
•The distance to Geneva- L=6160km
•Calculated time of Earth quake begin
Tcalc=6h 21 min in Siberia (world time)
practically coincides with the published Tpub=6h 17 min
•Amplitude of angular oscillations was 2 10-6 rad
The angular component of the Earth quake
Measurement 28 Febr. 2012 3h 17min AM
4,4
4,2
•The observation of an earth surface
“single inclination” effect
•Amplitude was a few μrad
4,0
3,8
Dev(rad)
(rad)
10,0
3,6
3,4
3,2
3,0
2,8
2,6
2,4
0
1
2
3
Time (min)
Earth surface single oscillation
Earth angular surface oscillations of an industrial noise origin
Industrial origin noise:
-high activity of auto– traffic,
-works in the neighboring
(with our set-up) Lab room,
-people movement
close to detecting set-up etc.
7
6
Dev(rad)
5
4
C
Dinner time
D
σ values :
3
2
A
-in work period(CD) 0.3 μrad
-In dinner time(AB) 0.04 μrad
B
1
11
12
13
Time (h)
The day measurement angular movement of the concrete floor
12,5
12,4
Dev (rad)
12,3
12,2
12,1
Concrete floor inclination due
to man presence in 3 meters distance
from the experimental set-up
Amplitude was 0.3μrad
0.3 rad
12,0
11,9
11,8
11,7
11,6
11,5
11,4
0
1
2
3
Time (min)
The measured inclination of the concrete floor
The microseismic peak observation by ground angular motion
0,14
0,12
0,10
0,08
0,06
0,04
0
10
20
30
40
50
60
70
80
90
100
110
120
Time(sek)
The seismogram of an earth surface angular oscillation
at the “microseismic peak” frequency
0,05
Amplitude (rad)
Dev(rad)
0,16
Amplitude of Earth surface oscillation at
the “microseismic peak” frequency was
0.03μrad with frequency fd=0.13Hz.
Inclinometer sensitivity estimate gives
≈5·10-9 rad.
0,04
0,03
0,02
A
B
0,01
fd
0,00
0,01
0,1
Frequency (Hz)
1
Fourier analyses of oscillation at the “microseismic peak
The long experimental setups space location stability and an
earth surface angular oscillations
Experimental Hall
Linear accelerator-collider
Line of horizon
θmp
θmp
The Earth surface fixed time picture:
surface deformation induced by the standing waves originated by
the interference of “microseicmic peak”
The accelerator-collider positioning on the earth
surface deformed by the microseismic peak wave
Different accelerator parts are inclined relative to the ”basic” horizontal
line and consequently particle beams going through the focusing elements
leave them with some angular spread θmp relative to the nominal.
As a result it leads to random motion of position of focuses accelerators
If we can stabilize the angular movements of the accelerator with an
accuracy of 10-9rad we will be able to stabilize position of its focuses to
within 50 nm
16
Conclusion
As a summary, different technical issues of a 150 m and accuracy 10μm LFL in
atmospheric air were discussed, showing that the combination of:
 Single mode laser associated with a fiber beam coupler
for the light emitting point
 An optimal laser ray focusing collimation
 An intermediate sensor having no impact on the straightness of the beam
 The calibration of each sensor
 The suppression of air media refraction index and long term
variation of temperature
 The isolation of the laser source from angular seismic industrial noise
can lead to an alignment system providing the location of points within 10µm.
Such an alignment system opens new perspectives
to reach a new precision level of alignment for projects like CLIC, ILC.
An original method for precision measurements when alignment of beam pipe ends on a
reference axis has been proposed and tested. The test measurements have been
performed using jointly the LRL in a 2D local coordinate system and a Total Station
survey instrument in a global 3D coordinate system. The fiducial marks at the pipe ends
have been measured with both instrumentations. A transformation to a common
coordinate system has been applied to allow the comparison of the results.
The results of the measurements coincide to an accuracy of approximately ±100 µm in
the directions perpendicular to a common reference line close to the laser beam and for a
17
pipe placed at the middle of a 50m line.
Conclusion
The ground motion was studied by the detection of an earth surface angular
oscillation. Instrumentally method is based on the conceptually new design
laser inclinometer using the reflecting surface liquid, as a space stable
(horizontal) reference level. The achieved inclinometer measurement precision
was experimentally proved to be ≈5·10-9 rad.
The achieved laser inclinometer sensitivity was proved by observation (in
Geneva) of:

Ground 2µrad oscillation caused by the Siberian earth quake (6160 km);

Single 1÷2 µrad oscillation of origin to be studied;

Industrial origin noise of about 3 10-7 rad amplitude;

Microseismic peak for the first time recognized as a ground ≈3 10-8rad
angular oscillation at 0.13Hz frequency.

The last observed effect if properly “compensated” by adequate
instrumental method could give significant colliders luminosity increase by
reduction of beams intersection area to about 50nm level (an estimate) due to
some suppression of the lateral focus effect.

The instrument of this sort may happen to be useful for modern high
precision research equipment stabilization, for example, of large telescope to
reach an extreme resolution.