DANGER
Laser Safety at Jefferson Lab
Conventional Class 3b and 4 Lasers
Free Electron Laser
Orientation Objectives
• Fundamentals of Laser Operation
– film: laser classification system
• Overview of ANSI Standard for the Safe Use
of Lasers
• Biological Effects of Overexposure to Laser
Radiation
Laser light source
Incandescent light source
1.
1.
2.
2.
3.
3.
Medical
Approval Form
CDRH/ANSI Hazard
Classification
• Class 3a
– These lasers can be visible, IR or UV.
– Direct viewing may cause eye injury.
– Laser power is <1 mWatt
• Class 3b
– These lasers can be visible, IR or UV.
– Direct and indirect viewing may cause eye injury.
– Laser power is between 5 and 500 mWatt
CDRH/ANSI Hazard
Classification
• Class 4
–
–
–
–
High power lasers
Direct and Indirect Viewing Hazard
Fire Hazard
Laser Power is >500 mWatts
• Special Considerations:
– invisible beams
– frequency doubled lasers
Conventional Lasers
•
•
•
•
•
•
CO2
nitrogen
argon
diodes
FIR
excimers
Free Electron Laser Facility
• Tunable Infrared Laser
• medium occupies
below grade area
• 6 user labs on upper
level
• FEL Control
room/center for laser
ops
FEL Theory
Jlab FEL Schematic
FEL Specifications
CW Operation
Average Power
Wavelength range
Micropulse energy
Pulse length
PRF
Bandwidth
Beam diameter at lab
600-1000 W
6.5-3 µm
~25 µJ
~2 ps FWHM nominal
37.425 MHz, 18.7125 MHz
~ Fourier transform limited (~ 0.2-0.5%)
down to 100 microns
Pulsed Operation
Planning to develop the capability of pulsed operation at rates from single
pulse up to 5 kHz.
Eye Physiology
Conventional Laser Safety
Program
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•
•
•
Responsibility/Authority
Procedures
Required controls
User Qualifications
Responsibility/Authority
Laser Safety Officer
Laser System Supervisor
Procedures
Laser Standard Operating Procedure
(LSOP)
• Author: LSS
• Approvals: Management, LSO
User Qualifications
• General laser safety orientation
• Laser Specific safety training
• Medical Approval
Class 3b Required Controls
• Same as Class 4 with two exceptions:
1. interlocked smoke detector not required
2. crash button not required
Class 4 Required Controls
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•
•
•
Smoke detector interlock to laser power
Entrance door interlock to shutter or power
Yellow beacon inline with power
Crash button inside and outside the laser
area
• Emission time delay 10 second minimum
• Approved schematic of safety interlock
system
Special hazards associated with
the FEL: The Accelerator
accelerator hazards
• vacuum
• ionizing radiation
• high voltage
• cryogenics
Special Hazards Associated with
the FEL: User Lab Issues
• User equipment
• Power levels
• Picosecond pulse
structure
• Harmonics
• Tunability
• Vacuum
Power
Picosecond Pulse Structure
• Existing ANSI
standard does not
address MPE’s for
picosecond pulses
• picosecond pulse
structure may be more
efficient in causing
injury
Harmonics
• Estimate : 10-h ,where
h is the harmonic.
• Estimate because
harmonics may be
lowered by optical
transport system
• some data suggests
increases in estimates
associated with the
higher harmonics
Tunability: Laser Safety Goggles
OD 5+ @ 1064 - 1400nm
OD 4+ @ 1400 1600nm
OD 4+ @ 2100; 2800 - 3200; 10,600nm
7.00
Filter 96
6.00
5.00
4.00
OD
3.00
2.00
1.00
Wavelength (nm)
2950
2700
2450
2200
1950
1700
1450
1200
950
700
450
0.00
200
• KG3 material
• window at 2.7
microns
• mitigation:
1. find a material that
absorbs at 2.7
microns and
sandwich it to the
KG3
2. for now, no lasing at
2.7 microns
Vacuum Issues
• Must transport beam
in vacuum to minimize
effects of CO2 / H2O
on the beam
• Optical transport
system user interface
is vacuum window
• window must be
protected to avoid loss
of vacuum
Special Hazards Associated with
the FEL: Personnel Issues
Two categories of
experimenters/Safety
Cultures
• Jefferson Lab
Employees
• Users
User Labs: Additional Controls
• Robust laser safety interlock system
• FEL control room with permissive to user
shutter
• video camera monitoring
• Experiment Approval Process
Bootstrapping An FEL Laser
Safety Program
• Benchmarking
• Peer Reviews
• Laser Expert audit
meetings
meetings
arguments
Benchmarking
• Information gathering from other FEL
facilities
• Drawing on past experience
• audit of three high energy laser labs
Reviews/Audits
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•
Accelerator Readiness Review
Personal Safety System Review
Laser Safety System Review
Anteon Audit