Laser Flashcards
LASER
Light amplification by stimulated emission radiation
New global system classes
1
1M
2
2M
3R
3B
4
NOHD
Nominal ocular hazard distance
EOHD
Extended ocular hazard distance
Effects of Laser
Skin/ tissue damage
Eye damage
Other[fire,poisonous,]
Explain Laser Energy
Monochromotic 1 colour same wavelength in phase
Output
1W =1000mW
1J = 1000mJ
Wavelength
1000000000nm =1m
Divergence
1mr = 1000radians
1° = 17.5932529
Permanent eye damage can be a result of
Direct illumination of the eye
Indirect illumination [reflected]
Types of reflection
Diffuse - objects that reflect in many directions
Specular - mirror like objects reflect in one direction[most dangerous]
MPE
Maximum permissible exposure [ maximum dosage of radiation considered to be safe from causing permanent eye damage
MPE depends on 2 things
Laser wavelength
Exposure time
Laser light vs normal light
NL non coherent light where waves are not in phase- beam spreads
LL coherent light where waves are in phase beam much more directed
Skin damage typesx2
Thermal - or burn tissue is heated to the point denaturation of protien occurs
Photochemical- light triggers chemical reactions in the tissue
Laser classification
American & new global system
1M
Safe for unaided viewing but may be hazardous if collecting optics are employed within the beam
-LRF
2M
Same ocular hazard as 2 may be hazardous if collecting optics are employed within the beam
-Laser pointers
3R
Potentially hazardous but the probability of injury is small.
Not capable of causing skin damage
Cannot produce hazardous diffuse reflection
Blinking reflex can protect if lasers visible
Laser pointers
NOHD formula
=MPE-distance+risk assessment + operative considerations
EOHD
Extended optical hazard distance
EOHD safe distance depends on x3
Diameter of lens
Magnification of optics
Loss of energy in lenses
Laser areas of use
Commercial
Industrial
Medical
Military
Scientific
1
Not hazardous under reasonably forsewable conditions even if the beam is viewed with up to and including 50mm collecting optics
-Cd players
2
Limited to the visible part of the ems 400-700nm where protection is afforded by the blinking reflex to bright light including upto 50mm collecting optics
Prolonged staring can be harmful especially shorter wavelengths
Laser pointers
3B
Are hazardous but viewing diffuse reflections are typically safe
Probability of skin injury unlikely
Laser pointers
4
Most hazardous &capable of causing damage to eye and skin
May produce hazardouse diffuse reflections, ignite flammable materials and produce airborne contaminants
Laser designators
OD
Optical density
Defined as logarithmic
Googles ability to protect
Laser class depends on 2 things
Effect
Wavelength
