Monitoring laser

Contents :

I PresentationII Safety &triggerIII AnalysisIV Next actions

Monitoring laserDavid BAILLEUX

1

Krypton lampYLF

Ti:S

YLF

Ti:S

Output

I Presentation

David BAILLEUX

3Monitoring laser

YLF Ti:S 527nm 440nmPulse energy 10mJ 1mJPulse width 40n 40nsPulse power 250kW 25kW

YLF = Yttrium Lithium Fluoride

Principe: optical pumpage..

I Presentation

David BAILLEUX

4Monitoring laser

Pump + heat exchanger

Cooling:

Transfo (110V)Inlet

Outlet

Laser Settings

I Presentation

David BAILLEUX

5Monitoring laser

Remote controls:

- wavelength- energy

Record data for 2 lasers :histogram and history

- energy- pulse width- pulse center- wavelength

Waveform Display

III Safety, trigger

David BAILLEUX

6Monitoring laser

Safety:A TTL level input is required on the safety module.

No TTL signal shutter of YLF laser closed

This TTL signal is off if :- the door is opened,- the main fiber is broken, or no light on pin diode.

An interlock is provided to close the laser shutter (pump) in case of unexpected opening of the laser room door.The interlock also functions if optical fibers were accidentally broken or removed. This is achieved by the level 2 TTL input, provided byFanouts …TTL signal at high level if the level fanouts receive laser pulse.

III Safety

David BAILLEUX

7

External trigger :

Timing signal form YLF laser

External trigger

Level TTL signal

TRIGGER = Timing signal

EVT

PIN NIVEAU 2

FIBRE HS

GENE porte rapide

END of porte

SECURITY LASER

Security laser(TTL level)

4 us

GENE T0(manual switch)

FIBRE OK

*T

*T > tps de transmission ds las fibres + tps de propagation du signal ds les cables.

No event no more light security laser = low level shutter closed

David

BAILLEUX9

III Analysis

Monitoring laser

26 A working point

YLF 2000 mW

Ti:S 110 mWEnergy from

0 to 100 %, soft0 mW Output Ti:S 1,1 mW

Neutral density filter 1/100

Results after calibration

III Analysis

David BAILLEUX

10

/mean=1 % /mean=3 %

/mean= 1.6 % /mean= 2.1 %

New lampPlot from 2 Oct

(27 Oct)

Old lamp(31 August)

YLF

YLF ENGY YLF FWHM

David

BAILLEUX11

New lampPlot from 2 Oct

(27 Oct)

Old lamp(31 August)

/mean=7.7 % /mean=7.5%

/mean= 4.9 % /mean= 4.3 %

Ti:S ENGY Ti:S FWHM

Ti:S

David

BAILLEUX12

III Analysis

Variations p-p:40%

With new lamp(27/09)

End of stabilization

Variations p-p:5%

In August

66 h

III Analysis

Variations p-p: 10%

With new lamp

Long term

David BAILLEUX

13

10 j

- Lamp has to be replaced every 2000 hours (83 days), Degradation is about 10% at 1000 h and 20% at 2000 h

- Wavelength : problem from 440 to 500 nm : no light at 500 nmfine tuning needed, service from Quantronix (similar problem in Caltech)Forecast : ready in 2 weeks ?

-Next year: software improvement: Now data are recorded every 1 s (scope limitation)

Laser events = 2000/mn DAQ record 20 events/mn (0.3 Hz) data during all test beam

probe for temperature inside the laser barrack new laser installation Feb 2003 ?

Summary