We dont want this

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We dont want this!
lesions
Optic nerve
Fluorescein angiograph of retina after laser
irradiation
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We dont want this!
When the beam struck my eye I heard a distinct
popping sound, caused by a laser-induced
explosion at the back of my eyeball. My vision
was obscured almost immediately by streams of
blood floationg in the vitreous humor, and by
what appeared to be particulate matter suspended
in the vitreous humor. It was like viewing the
world through a round fishbowl full of glycerol
into which a quart of blood and a handful of
black pepper have been partially mixed. There was
local pain within a few minutes of the accident,
but it did not become excruciating
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Instruction is mandatory! Training is essential
for your safety!
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Light Amplification by the Stimulated Emission
of Radiation
Monochromatic

• Monochromatisch (smal spectrum)
• Coherent in de tijd (fase blijft behouden)
• Coherent in de ruimte (interferentie, spikkel
  patroon)
• Kleine divergentie (goed focuseerbaar)

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Directional
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Coherent
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Laser components
Lasing medium
Optical cavity
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De onderdelen van een laser
Plasma buis

Uitgang- spiegel
Spanningsbron gelijkstroom
100 reflector

• De drie belangrijkste onderdelen van een laser
• pomp om medium te exciteren
• medium met optische versterking
• optische trilholte

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Het laserende medium

• Gas
• He - Ne 632.8 nm
• Ar 514.5 nm .
• Kr 647 nm .
• CO2 10.6 mm
• Vaste stof
• Robijn (Cr3) 694 nm
• Nd YAG 1064 nm
• Halfgeleider
• AlGaAs 780 - 870 nm
• InGaAsP 1300-1600 nm
• Vloeistof
• Rhodamine 6G 580 - 630 nm

Het medium bepaalt de golflengte van het licht
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Focuseerbaarheid
Ideale bundel
Fictief beeld punt
f
h0
h1
S
S
laser
d
f
Focus laser bundel
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PULSED LASERS
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• Pupil
• Aperture of the eye. 
• Normal range of 2 - 7 mm.
• Range decreases with age. 
• 7 mm is used for hazard calculations.

• Cornea
• Living, protective tissue
• Transparent, 0.5 mm thick
• Mean index of refraction 1.376
• (? 70 of the refractive power)
• High metabolic rate
• (rejuvenating itself in 24 to 48 hours)

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• The retina is an extension of the brain and
  consists of several complex layers of nerve
  cells.
• Made up of rods and cones - rods for night and
  peripheral vision, cones for color and
  resolution.

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315 - 400 nm
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• Near Ultraviolet Wavelengths (UVA) 315 - 400 nm
• Most of the radiation is absorbed in the lens of
  the eye.
• The effects are delayed and do not occur for
  many years (e.g. cataracts).
• Far Ultraviolet (UVB) 280 - 315 nm and (UVC) 100
  - 280 nm
• Most of the radiation is absorbed in the cornea.
  
• Snow blindness/welder's flash) will result with
  high doses.
• Visible (400 -760 nm) and Near Infrared (760 -
  1400 nm)
• Most of the radiation is transmitted to the
  retina.
• Overexposure may cause flash blindness or
  retinal burns and lesions.
• Far Infrared (1400 nm - 1 mm)
• Most of the radiation is transmitted to the
  cornea.
• verexposure to these wavelengths will cause
  corneal burns.

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Chicken wing
hotdog
250 Watt Laser Moving at 1 Inch per Second
250 Watt Laser in Single Pulses
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• Electrical Hazard
• Uncovered electrical terminals.
• Improperly insulated electrical terminals.
• Hidden "power up" warning lights.
• Lack of training.
• "Buddy system" not being practiced
• Non-earth-grounded or improperly grounded laser
  equipment.
• Non-adherence to the OSHA lock-out standard
  (29CFR1910.147).
• Excessive wires and cables on floor that create
  fall or slip hazards

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• Laser Dyes and Solvents
• Dyes are used in some lasers as a lasing medium. 
  
• These dyes are complex organic compounds that are
  mixed in solution with certain solvents. 
• Some dyes are highly toxic or carcinogenic, and
  great care must be taken when handling them,
  preparing solutions, and operating lasers that
  contain these dyes. 
• A Material Safety Data Sheet must be made
  available to anyone working with these dyes.

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From ANSI Z136.1 (2000) causes for accidents

• Unanticipated eye exposure during alignment
• Misaligned optics and upwardly directed beams
• Available eye protection not used
• Equipment malfunction
• Improper methods for handling high voltage
• Intentional exposure of unprotected personnel
• Operators unfamiliar with laser equipment
• Lack of protection for ancillary hazards
• Improper restoration of equipment following
  service
• Eyewear worn not appropriate for laser in use
• Unanticipated eye/skin exposure during laser
  usage
• Inhalation of laser-generated air contaminants
• Ignition of fires of both a facility or
  personal nature
• Eye or skin injury of photochemical nature
• Failure to follow standard operating procedures
  (SOPs)

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• Engineering controls
• have eye protection for personnel
• protective housing with interlocks on removable
  parts
• a key-controlled master switch shall be provided
• the entire beam should be enclosed as much as
  possible
• warning light and sings should exist at the
  entrance
• be supervised by an individual with knowledge of
  laser safety
• have limited access to spectators
• have beam stops to terminate dangerous laser
  beams
• be designed to reduce diffuse and specular
  reflections
• not have a laser beam at eye level with people
• restrictions on windows and doorways to reduce
  exposure
• require disabling of the laser when it is not
  being used

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