• What’s already existing? What’s already existing? • Laser system & impacts on Laser system & impacts on Optics Transport Optics Transport – Laser power Laser power – Focusing optics Focusing optics – Lens tolerances & Lens tolerances & system alignment system alignment – Scanning range Scanning range • Summary Summary [email protected]3 rd rd Mini-Workshop on Nano Project at ATF/KEK Mini-Workshop on Nano Project at ATF/KEK 30 30 th th May 2005 May 2005 Optics Transport for the Laser-wire Optics Transport for the Laser-wire at the ATF Extraction Line at the ATF Extraction Line Laser-wire Team Laser-wire Team
Transcript
• What’s already existing?What’s already existing?• Laser system & impacts on Laser system & impacts on
Optics TransportOptics Transport– Laser powerLaser power– Focusing opticsFocusing optics– Lens tolerances & system Lens tolerances & system
33rdrd Mini-Workshop on Nano Project at ATF/KEK Mini-Workshop on Nano Project at ATF/KEK
3030thth May 2005 May 2005
Optics Transport for the Laser-wire Optics Transport for the Laser-wire
at the ATF Extraction Lineat the ATF Extraction Line
Laser-wire TeamLaser-wire Team
2
What’s already existing?
A tiny change is needed in order to bring the laser beam to the focusing optics:
- Breadboard underneath the pipe - Pick-up the beam at MS1
Present setup for the e+ polarisation experiment
MS1M2
3
Laser Power
Laser Damage Threshold (LDT):
Best Coating 20 Joules/cm2 @ 532 nm, 8 ns.
E = 300 - 600 mJoulesPulse length = 200 - 300 psBeam diameter 2.R = 6 mm
Power density = 600 mJoules
. R2
= 2.1 Joules/cm2
13.3 Joules/cm2
LDT (8 ns) = 2.1 Joules/cm2 . 8 ns
0.2 ns
½
Safety factor is not enough !
Attenuate the beam to a couple of 10’s MW several 1000’s of photons.
4
Goal = Achieve a 1m spot size:
f = ./1
/1 aspheric lens
Simulation
Input waist ≥ 20mm
3” optics post- BE @45°
2” optics is appropriate.
Focusing Optics
Tight tolerance on the lens:
< 0.3 degrees tilt
< 0.5 mm decenter
CCD1
CCD2
MS1
MS2
MS1 = Steering mirror 1MS1 = Steering mirror 1
Setup is being developed at RHUL
5
Scanning range
σ = e-beam size
N= number of sigma scans
Scanning range is: = N x σ /f
Example: f = 60 mm & N = ± 5
(m) 1 6 (mrad) 0.08 0.5
Scan angle over exaggerated
Scanning is done with a Piezo driven Scanner:
PI S330: = ± 2.5 mrad, f=1KHz,
good repeatability.
Other options (A.O & E.O) are being investigated.
6
e-beam
z
x
3000
1000Breadboard
e-beam
z
xIP
Pick-up
Beam Expander
Shutter
MS1
Scanning Mirror
2650
100
200
1200
400
1290
700
960
EM
ZEMAX screenshot of the beam path
CCD1
Green
red
IrisIris
CCD’2
CCD3
MS2
EM
MS_F1
MS_F2
-Beam dumps are not shown-Fast photodiode is not shown-Some of the equipment are movable and multi-task: CCDs alignment, waist monitor, collimation)
7
Zemax Simulation
Waist at IPAberrations
Encircled energy
8
Summary & Plan
- KEK agreed to prepare the breadboard for us, its support, and its enclosure as well.
Many thanks !
- Thanks to our colleagues from the e+ Polarization experiment, the beam is delivered to the breadboard in the tunnel.
- The UK-group will take responsibility of getting all items needed on the breadboard (focusing, alignment, diagnostics, …) A shopping list is prepared will start ordering the items starting from next week.
- The setup will be tested in the UK before being shipped to KEK in September
