L a s e r S a f e t y a t J e f f e r s o n L a b

C o n v e n t i o n a l C l a s s 3 b a n d 4 L a s e r sF r e e E l e c t r o n L a s e r

D A N G E R

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

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3.

Incandescent light sourceLaser light source

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 600-1000 W Wavelength range 6.5-3 µm Micropulse energy ~25 µJ Pulse length ~2 ps FWHM nominal PRF 37.425 MHz, 18.7125 MHz Bandwidth ~ Fourier transform limited (~ 0.2-0.5%) Beam diameter at lab 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

• 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

• 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

• 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

Filter 96

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7.00

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45

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70

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95

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50

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Wavelength (nm)

OD

OD 5+ @ 1064 - 1400nm OD 4+ @ 1400 - 1600nm

OD 4+ @ 2100; 2800 - 3200; 10,600nm

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

meetingsmeetingsarguments

Benchmarking

• Information gathering from other FEL facilities

• Drawing on past experience

• audit of three high energy laser labs

Reviews/Audits

• Accelerator Readiness Review

• Personal Safety System Review

• Laser Safety System Review

• Anteon Audit