laser safety andras kis zettl group safety talk 11/16/2006

Laser Safety

Andras KisZettl group safety talk

11/16/2006

Laser Components

• Light Amplification by Stimulated Emission of Radiation

Associated hazards:

1. Laser Beam: eye injury, burns, skin cancer (UV), fire hazard

2. Active medium: toxic chemicals or gases (organic dyes, BeO in Ar lasers, HF, HeCd, HeHg, HeSe)

3. Excitation source: high voltage, water cooling

OPTICAL RESONATOR

excitation

Active medium

LASERbeam

high reflectancemirror

output couplermirror

Human Eye- laser beam can be focused by cornea and the lens to a very tight spot on the retina

400-1400 nm<400, >1400 nm

<400, >1400 nm

Burns, cataracts

Retinal damage

Eye Injury

Eye Injury From A Pulsed Laser

Skin Burns

• CO2 laser reflected from a metal surface

Types of laser eye exposure

Laser hazard classes

• Classification by wavelength and output power, according to their ability to produce damage

Class Power Remarks Typical examples

I Very low or beam completely enclosed

•Inherently safe,•No possibility of exposure

CD, DVD drives, laser printers…

II 1 mWVisible only

•Staring into the beam is hazardous•Eye protected by aversion response

Supermarket laser scanners, some pointers

IIIa 1-5 mW •Aversion may not be adequate Laser pointers

IIIb 5-500 mW •Direct exposure is a hazard Ar laser in Birge 123CF microscope in B219

IV >500 mW •Exposure to direct beam and scattered light is eye and skin hazard•Fire hazard

Laser ablation setup in Birge 266

Labels on setups

Class IIClass IIIa with expanded beam

Class IIIa with small beamClass IIIbClass IV

Safety measures

• Be informed

• Eyewear for classes IIIb, IV for everybody in the room

• Beam paths above >200 mW should be guided through tubes

• Highest risk during alignment, optical setup modification

IIIb and IV requirements

• EHS 280 Laser Safety Training

• EHS 281 Laser Safety Retraining (every 3 years)

• On the Job Training – provided by PI/supervisor & documented in the Activity Hazard Document

• Laser eye exams

Links:

UCB laser safety

LBL laser safety