Lasers Flashcards
Class 1
No risk to skin and eyes
Safe for long-term intra-beam viewing
Completely enclosed
Examples: DVD player, laser cutting system
Class 1M
No risk to skin and eyes
Safe for long-term intra-beam viewing
Hazardous if viewed with magnifying optics
Examples: laser diodes, speed meters
caution warning
Class 1C
No risk to eye if laser remains in contact with tissue
AEL stopped or reduced below AEL of Class 1
Example: at home laser hair removal
follow instructions for use labelling
Class 2
Visible beams
No skin risk
Safe for momentary intra-beam viewing and with optical instruments
Hazardous for deliberate viewing
Blink response/ head movement
Example: laser pointer
do not stare labelling
Class 2M
Visible beams
No skin risk
No risk to eye for short intra-beam viewing
Blink response/ head movement
Possible eye injury using viewing instruments
Example: alignment laser for CT
yellow caution label
Class 3R
Low risk to eyes for intentional viewing
No risk to skin
Professional use
Example: alignment or levelling lasers
Class 3B
Risk to eyes from intra-beam viewing
Diffuse viewing is safe
Low risk to skin
Examples: physiotherapy, broadband sources
amber warning label
Class 4
High risk to eye for both direct and diffuse viewing
High risk to skin
Fire hazard
Examples: surgical lasers, cutting
red danger labelling
Components of Laser Eyewear Marking Scheme
1064 D LB7 X CE95
1. Wavelength range
2. Test condition
3. Protection factor
4. Approve inspection body test mark
5. Conformity test mark
Test conditions for laser eyewear marking scheme
D = continuous wave
I = long pulsed
R = Q-switched
M = Mode-locked
Two main laser safety regulations
Control of Artificial Optical Radiation at Work Regulations
Artificial Optical Radiation Directive
Health and Safety at Work Act is also relavent
Aim of laser standards
to ensure consistency in manufacturing or a particular task
IEC (International Electrotechnical Comission)
What are laser classifications based on?
- eye and skin risks
- conditions of use, exposure time or environment
- accessible emission limits (AEL)
- maximum permissible exposure (MPE)
- worst case assumptions
can be used as a guide for a risk assessment
What is accessible emission?
The power or energy of radiation emitted by the laser that is accessible.
Is compared to the AEL under various standard conditions.
What are the conditions under which AEL values are compared?
Timeframe
Limiting aperture
Distance
Source size
What is the time basis of 0.25s used for?
Class 2, 2M and 3R
400-700 nm
Blink response
What is the time basis of 100s used for?
all wavelengths greater than 400nm
aversion response
What is the time basis of 30,000s used for?
all wavelengths <= 400 nm
all wavelenghts > 400 nm where intentional long term viewing is inherent
working day
What is the retinal hazard region?
400 - 1400 nm
What are the manufacturer safety requirements for class 3B/4 lasers?
remote interlock
emission warning
beam stop
key-switch
safety docs
aiming beam
NOHD
audible or visible beam on indicator
eye protection
What are the manufacturer safety requirements for all classes except 1?
safety lables
aperture marked
What does the Control of Artificial Optical Radiation at Work Regs require employers to do?
assess the risk of adverse health effects to the eyes and skin
eliminate or reduce risks below Exposure Limit Values
inform and train staff
provide health surveillance and medical examinations
What is the manufacturing standard and what does it cover?
BS EN 60601
basic safety and essential preformance
electrical safety, voltage, graphic symbols, safety measures
covers class 3B and 4 lasers
What is the safety standard and what does it cover?
BS EN 60825
safety measures, wavelengths, marking, physilogical effects
laser guards
safe use of lasers on humans (class 1C, 3B, 4)
guidance for best practice (MPE, NOHD)
eye protection
surgical drapes
Maximum Permissible Exposure
highest power or energy density of a source that is considered safe (J/m^2 or W/m^2)
depends on wavelength, exposure time, observation geometry
5 steps of a risk assessment
- Identify Hazard
- Identify who may be harmed and how
- Evaluate risks and decide on control measures
- Record findings and implement them
- Review and update if necessary
What are the hazards relating to the use of lasers?
- Equipment (fire, trip hazard)
- Process (plume, internal fire)
- Environment (controlled area, reflections, interlocks)
- Personnel (staff, patient)
What is the Nominal Ocular Hazard Distance?
distance at which the beam irradiance or radiance exposure = MPE
What is the heirarchy of controls?
- Elimination
- Substitution
- Engineering Controls
- Administrative Controls
- PPE
Who are the duty holders?
LPS
Clinical Laser Expert
LPA
LSO
When are local rules required?
for every class 3B and 4 laser
MHRA provides guidance on what should be included
