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Laser Safety > LSO 06: Beam Hazards > Flashcards

LSO 06: Beam Hazards Flashcards

1
Q

What is MPE ?

A

amt of brightness safe to view for defined period

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2
Q

What is AEL ( accessible emission limit)?

A

maxm total power of laser radiation that can be emitted from the laser. It applies for laser manufacturer not for laser user

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3
Q

What is limiting aperture dependent on?

A

Laser wavelength, and other physical factors

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4
Q

What does higher classifications mean?

A

Higher risk of injury should accidental exposure occur

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5
Q

What are Class 1, Class 1M lasers?

M= magnifying optic

A

Safe under reasonable foreseeable conditions of operation, bean is inaccessible, visible and invisible wavelengths

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6
Q

What are Class 2/2M lasers?

A

low power visible wavelength lasers ( Should be visible), aversion response, AEL = 1mW for a CW laser

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7
Q

What are Class 3R lasers?

R= reduced requirements

A

Risk of injury is greater than for lower classess. AEL= 5mW ( continuous wave laser)

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8
Q

What are Class 3B lasers?

A

hazard from direct, Intra-beam viewing , specular reflection……. It is safe is view the diffuse reflection as long as its 13 cm from source and only 10 sec
AEL= 500mW, no fire hazard or combustion hazard

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9
Q

What are Class 4 lasers?

A

Direct intrabeam viewing is hazardous, specular and diffuse reflections is hazardous. eye, skin and fire hazard. more than 500mW

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10
Q

which class of laser has an AEL between 1-5 mW for a CW laser?

A

Class 3R

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11
Q

NHZ

A

Nominal Hazard Zone “ the space within which the level of the direct, reflected or scattered radiation may exceed the applicable MPE. Exposure levels beyond the boundary of the NHZ are below the appropriate MPE

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12
Q

Nominal Ocular Hazard Distance

A

The distance along the axis of the unobstructed beam from a laser, fiber end or connector to the human eye beyond which the irradiance or radiant exposure is not expected to exceed the applicable MPE

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13
Q

A class 3B laser with an NHZ of 30 cm is located in a lab. The laser operator stands no closer than 42 cm away from the laser during operations. Does this present a hazard to the operator?

A

No

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14
Q

Aperture

A

An opening window or lens through which optical radiation can pass

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15
Q

Intrabean Viewing

A

The viewing condition whereby the eye is exposed to all or part of a laser beam

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16
Q

Point source viewing

A

the viewing condition whereby the angular subtense of the source is equal to or less than the limiting angular subtense. less than 1.5mRad…..viewing through telescope is point source viewing

17
Q

Telescopic Viewing

A

viewing an object from a long distance with the aid of an optical system that increases the visual size of the image.

18
Q

Retinal Hazard Region

A

Optical radiation with wavelengths between 0.4 and 1.4 um ( 400-1400nm)

19
Q

Beam Geometry

A

can be described by: path of travel for laser beam, shape of the beam

20
Q

What is beam profile?

A

The distribution of irradiance or radiant exposure across the beam, perpendicular to the beam propagation direction

21
Q

Gaussian Beam Profile

A

Laser generate a beam with a cross-sectional energy distribution that can be described mathematically by a gaussian type distribution

22
Q

Top-hat beam profile

A

gives uniform beam energy across the diameter of the beam

23
Q

What are the ways a person may view a laser beam?

A

Intrabeam, specular reflection, diffuse reflection, infra beam, lens or laser

24
Q

what is infra beam viewing?

A

Eye directly in the path of laser beam

25
Q

What is specular reflection?

A

A beam is reflected off of a mirror like surface and directed into the eye

26
Q

What is Intrabeam, Lens-on- Laser viewing?

A

A beam is focused by a lens and directed in to the eye

27
Q

What is Diffuse reflection?

A

Beam reflects off of a non-mirror-like surface and enters the eye

28
Q

The viewing condition whereby the beam reflects off of a mirror like surface into the eye is

A

Specular reflection

29
Q

Beam Hazards

A

Ocular exposure to laser radiation in excess to the MPE will result in bioeffects
- Location of absorbance depends upon laser wavelength
type and extent of damage depends upon laser energy and duration of exposure

30
Q

Beam-initiated Fire

A

High concentration of radiant power that is observed with class 4 lasers can ignite materials that come in contact with the beam, flammable liquids, plastics, wood, fabrics

31
Q

Thermal hazards

A

non combustible material in the beam path of high power lasers may not burn but can get a very hot, can cause burns, laser components may become damaged or distorted

32
Q

what is LGAC

A

laser generated air contaminants. hazardous particulates and gaseous by products created by interaction of laser beam with matter
metals, organic material, plastics, glass tissue

Laser Safety (11 decks)

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