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    Laser Module 2

    Uploaded by

    Luis Enrique B G
    The document discusses laser safety and laser beam injuries. It notes that high power lasers can cause severe eye injuries and permanent vision loss from skin burns. It provides details on laser bioeffects on skin, including thermal burns, acoustic shockwaves, and photochemical effects. For the eyes, it describes the retinal hazard region from 400-1400nm and notes various laser wavelengths can cause damage to different eye tissues like the cornea, lens, and retina, potentially resulting in conditions like photokeratitis, cataracts, or permanent blind spots. Proper laser safety equipment is needed to prevent accidental exposure and injuries.

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    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd

    Laser Module 2

    Uploaded by

    Luis Enrique B G
    41 views24 pages
    The document discusses laser safety and laser beam injuries. It notes that high power lasers can cause severe eye injuries and permanent vision loss from skin burns. It provides details on laser bioeffects on skin, including thermal burns, acoustic shockwaves, and photochemical effects. For the eyes, it describes the retinal hazard region from 400-1400nm and notes various laser wavelengths can cause damage to different eye tissues like the cornea, lens, and retina, potentially resulting in conditions like photokeratitis, cataracts, or permanent blind spots. Proper laser safety equipment is needed to prevent accidental exposure and injuries.

    Original Description:

    Manual de seguridad para el manejo de láseres. 2

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    The document discusses laser safety and laser beam injuries. It notes that high power lasers can cause severe eye injuries and permanent vision loss from skin burns. It provides details on laser bioeffects on skin, including thermal burns, acoustic shockwaves, and photochemical effects. For the eyes, it describes the retinal hazard region from 400-1400nm and notes various laser wavelengths can cause damage to different eye tissues like the cornea, lens, and retina, potentially resulting in conditions like photokeratitis, cataracts, or permanent blind spots. Proper laser safety equipment is needed to prevent accidental exposure and injuries.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    41 views24 pages

    Laser Module 2

    Uploaded by

    Luis Enrique B G
    The document discusses laser safety and laser beam injuries. It notes that high power lasers can cause severe eye injuries and permanent vision loss from skin burns. It provides details on laser bioeffects on skin, including thermal burns, acoustic shockwaves, and photochemical effects. For the eyes, it describes the retinal hazard region from 400-1400nm and notes various laser wavelengths can cause damage to different eye tissues like the cornea, lens, and retina, potentially resulting in conditions like photokeratitis, cataracts, or permanent blind spots. Proper laser safety equipment is needed to prevent accidental exposure and injuries.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 24

    Risk Management Services

    www.riskmanagement.ubc.ca

    Laser Safety and Program Development

    Laser Beam Injuries

    Laser Beam Injuries


    High power lasers can cause skin burns and severe eye injuries
    resulting in permanent vision loss.

    Laser Bioeffects: Skin


    1)Thermal:
    Most laser skin injuries are thermal in nature.
    Exposure to high power beams at all
    wavelengths can result in skin burns. These
    burns usually do not lead to long-term
    disability, but they can have painful short-term
    consequences.
    Far IR light, such as that from CO2 lasers, is
    absorbed strongly by water in the skin and
    results in a surface burn. Near IR light with
    wavelengths close to 1 mm, such as that from
    a Nd:YAG laser, penetrates more deeply into
    tissue and can result in deeper, more painful
    burns.

    Skin Sensitivity:
    - Epidermis (UV-B, UV-C)
    - Dermis (IR-A)

    Laser Bioeffects: Skin


    (Thermal continued)
    If a high power laser beam is focused on the
    skin, it can vaporize tissue and drill a hole or
    produce a cut if the beam or tissue is moving.
    CW beams will cauterize the tissue preventing
    bleeding. Focused short pulses form repetitive
    pulse Q-switched lasers vaporize tissue without
    heating the surrounding tissue enough to
    cauterize. Exposures to focused Q-switched
    beams can result in cuts several millimeters
    deep that bleed freely.
    Skin Sensitivity:
    - Epidermis (UV-B, UV-C)
    - Dermis (IR-A)

    Skin Burn from CO2 Laser Exposure

    Accidental exposure to partial reflection of 2000 W CO2 laser beam


    from metal surface during cutting

    Laser Bio-effects: Skin


    2) Acoustic:
    Localized vaporization of tissue can create a mechanical
    shockwave to be propagated through the tissue. These
    shockwaves can cause tearing of surrounding tissue.
    3) Photochemical Effects:
    Causes changes to the chemistry of cells, which can result in
    changes to tissue.
    Photochemical skin injuries include sunburn and the possibility
    of promoting skin cancer by repeated low level exposures over
    long periods of time. Chronic effects can include cataract
    formation and skin aging. The best way to avoid these issues is
    to enclose high power UV beams.

    Laser Bioeffects: Eye

    Visual Response

    Laser Spectrum
    Gamma Rays

    10-13

    10-12

    10-11

    X-Rays

    10-10

    10-9

    Ultra- Visible
    violet

    10-8

    10-7

    Infrared

    10-6

    10-5

    Microwaves

    10-4

    10-3

    10-2

    Radar
    waves

    10-1

    TV
    waves

    Radio
    waves

    10

    102

    Wavelength (m)
    LASERS

    Retinal Hazard Region


    Ultraviolet

    200

    300

    Visible

    400

    500

    600

    Near Infrared

    700

    800

    900

    1000

    1100

    Far Infrared

    1200

    1300

    1400

    1500

    10600

    Wavelength (nm)
    ArF
    193

    XeCl
    308
    KrF
    248

    Ar
    488/515

    HeNe Ruby
    633 694
    2w Alexandrite GaAs
    Nd:YAG
    755
    905
    532

    Nd:YAG
    1064

    CO2
    Communication
    10600
    Diode
    1550

    Lasers operate in the ultraviolet, visible, near infrared, and far infrared regions of the spectrum.

    Eye Anatomy of Concern in Laser Injury

    Microwaves and Gamma Rays

    Wavelength of microwaves are too large to interact with the


    eye
    Wavelength of Gamma waves are too small to interact with
    the eye (at the cellular level)

    The Retinal Hazard Region

    400-1400nm
    Affects the retina

    Optical Portion of Electromagnetic Spectrum


    UV-C (Extreme)

    1 - 280 nm

    UV-B (Far)

    280 - 315 nm

    UV-A (Near)

    315 - 380 nm

    Visible Light

    380 - 780 nm

    Near IR (IR-A)

    780 - 4000 nm

    Middle IR (IR-B)

    4um - 14 um

    Far IR (IR-C)

    14um 100 um

    Ultraviolet region
    UV-C (100280nm)
    Cornea surface
    UV-A (315400nm)
    Affects the lens

    UV-B (280-315nm)
    Absorbed by the cornea

    Absorption of UV on Different Parts of The Eye

    % UV
    nm Absorption
    100
    280
    6
    92
    300
    16
    45
    320
    37
    340
    14
    12
    34
    360

    2
    36
    48
    52

    1
    1
    2

    Ultraviolet Effects on the Eye


    UV-A
    Lens Absorption:
    (315-380nm)
    - Injuries permanent
    - Cataractogenisis
    - Elasticity loss
    Retinal Absorption:
    - Not normally affected
    - Possible if photosensitized
    UV-B/C
    Corneal Absorption:
    (280-315nm)
    - Photokeratitis (6-12hr onset)
    (1-280nm)
    - Conjunctivitis
    - Photochemical reaction
    - Permanent scarring

    Infra-red Region

    Near IR
    (< 1400nm)
    Affects the retina

    Far IR
    Affects cornea and aqueous humor

    Visible and Near Infrared Effects on the Eye


    Retinal Hazard Region: 400-1400nm

    Elevated irradiance at retina


    Partially a function of pupil size
    Exposure duration is critical
    Thermal injury by protein denaturation
    Acoustical damage

    Middle and Far Infrared Effects on the Eye


    Cataractogenisis: acute exposure

    Cataractogenisis: chronic exposure


    Corneal flash burns
    Thermal injury to conjunctiva, iris etc.

    25 m

    THERMAL BURNS
    ON PRIMATE RETINA
    Photo courtesy of U S Air Force

    This image shows the macula of the eye of a rhesus monkey. The light spots on this retina were produced
    by 0.25 s exposures to a green laser beam with a power of 10 mW. Each of these exposures heated the
    retinal tissue to the point that the protein cooked, producing a white burn.
    This is the most common type of laser eye injury in humans. It is likely that thousands of people have
    received these small retinal burns. They are permanent blind spots. If the burn is outside the macula, the
    effect on vision is small. If the burn is inside the macula, the effect is much greater. One such burn in the
    center of the macula will mean that you cannot thread a needle using that eye. A slightly larger spot or
    multiple spots will make reading difficult.
    This type of injury can be prevented by wearing laser safety eyewear.

    Multiple Pulse Retinal Injury

    This is an image of the retina of a human who experienced an eye injury from a repetitive pulse near
    infrared laser. The beam was invisible. In such cases people do not usually realize they are being exposed
    until their vision has been severely effected. The persons eye was moving during this exposure. This
    resulted in a line of laser burns on the retina. This is a color enhanced image to better show the laser
    damage.
    The macula of the eye is located out of the photo to the lower left. This individual was lucky that the
    damage did not extend into the macula.
    The correct laser safety eyewear would have prevented this injury.

    Eye Injury by Q-Switched Laser

    Photo courtesy of U S Army Center for


    Health Promotion and Preventive Medicine

    This is a human eye injury resulting from four pulses into the macular region from an AN/GVS-5 Nd:YAG
    laser rangefinder. The pulse duration was about 20 ns and the pulse energy was about 15 J. The safe
    exposure limit for this pulse duration is 2 mJ per pulse. Thus, this exposure was 7500 times the safe level.
    Short pulse lasers produce the greatest eye hazards. Each short pulse results in a tiny explosion in the
    retina. The resulting shockwave causes severe damage to the retinal tissue.
    This photo was taken three weeks after the exposure. It shows the permanent destruction of the macular
    region. Visual acuity in the eye is approximately 20/400 and will not improve.

    Corneal Burn from CO2 Laser Exposure of


    Rabbit Eye

    This is a surface burn on the cornea of a rabbits eye caused by exposure to a CO 2 laser beam of a few
    watts. All the laser energy was absorbed by water on the surface of the cornea. This heated the cornea
    causing the protein in the corneal tissue to cook.
    Human eye injuries from far infrared lasers have been rare, but they have occurred.

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