LSO 06: Beam Hazards

Question 1

What is MPE ?

Answer 1

amt of brightness safe to view for defined period

Question 2

What is AEL ( accessible emission limit)?

Answer 2

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

Question 3

What is limiting aperture dependent on?

Answer 3

Laser wavelength, and other physical factors

Question 4

What does higher classifications mean?

Answer 4

Higher risk of injury should accidental exposure occur

Question 5

What are Class 1, Class 1M lasers?

M= magnifying optic

Answer 5

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

Question 6

What are Class 2/2M lasers?

Answer 6

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

Question 7

What are Class 3R lasers?

R= reduced requirements

Answer 7

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

Question 8

What are Class 3B lasers?

Answer 8

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

Question 9

What are Class 4 lasers?

Answer 9

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

Question 10

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

Answer 10

Class 3R

Question 11

NHZ

Answer 11

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

Question 12

Nominal Ocular Hazard Distance

Answer 12

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

Question 13

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?

Answer 13

No

Question 14

Aperture

Answer 14

An opening window or lens through which optical radiation can pass

Question 15

Intrabean Viewing

Answer 15

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

Question 16

Point source viewing

Answer 16

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

Question 17

Telescopic Viewing

Answer 17

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

Question 18

Retinal Hazard Region

Answer 18

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

Question 19

Beam Geometry

Answer 19

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

Question 20

What is beam profile?

Answer 20

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

Question 21

Gaussian Beam Profile

Answer 21

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

Question 22

Top-hat beam profile

Answer 22

gives uniform beam energy across the diameter of the beam

Question 23

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

Answer 23

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

Question 24

what is infra beam viewing?

Answer 24

Eye directly in the path of laser beam

Question 25

What is specular reflection?

Answer 25

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

Question 26

What is Intrabeam, Lens-on- Laser viewing?

Answer 26

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

Question 27

What is Diffuse reflection?

Answer 27

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

Question 28

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

Answer 28

Specular reflection

Question 29

Beam Hazards

Answer 29

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

Question 30

Beam-initiated Fire

Answer 30

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

Question 31

Thermal hazards

Answer 31

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

Question 32

what is LGAC

Answer 32

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