Laser Safety Flashcards Preview

Health Physics > Laser Safety > Flashcards

Flashcards in Laser Safety Deck (28):
1

Which government agency regulates the classification and control measures Incorporated into laser products?

FDA

2

Conjunctivitis may result from a welding arc due to

UV radiation. The wavelengths responsible for conjunctivitis are 270-280 nm in the UV area of the electromagnetic spectrum.

3

The most important type of UV for causing cancer from sunlight is

UVB

4

Most biologically effective wavelength for killing microbes by UV

270 nm UVB

5

Eye exposure to a 1520 to 1570 nm laser results in damage to:

The Cornea. Wavelengths greater than 1400 nm are absorbed in the cornea

6

Laser wavelengths generally considered retina hazards

400 to 1400 nm

7

What is the usual unit for measurement of laser radiation

J/cm^2 or W/cm^2

8

Target organ for consideration of biological damage to humans from laser exposure is the

Eye. Skin is a close second.

9

Far infrared wavelength

1400nm to 1mm

10

Near Infrared wavelength

780 to 1400 nm

11

Visible electromagnetic spectrum

400nm to 780nm

12

Ultraviolet electromagnetic spectrum

Far: 200-315nm Near: 315-400 nm

13

Three areas of eye sensitivity

Retina, Lens, Cornea

14

Wavelengths that put the retina at risk

Visible, IR-A (near)

15

Wavelengths that put the lens at risk

UV-A

16

Wavelengths that put the cornea at risk

UV-B, UV-C, IR-B, IR-C

17

Class 1 laser

Laser cannot cause injury either because it is too low powered or because of engineered safety controls.

18

Class 2 laser

May be viewed for less than 0.25 seconds. The aversion response, which leads to a blink in less than 0.25 second, is sufficient to prevent injury to the eye. Max power level = 1 mW

19

Class 3a laser

Can injure the eye in intrabeam viewing for less than 0.25 seconds ,or viewing a specular reflection for less than 0.25 seconds. Max power level = 5 mW.

20

Class 3b laser

Same as 3a, except max power level = 500 mW, max radiant exposure = 10 j/cm^2 per pulse. ANSI 'DANGER' Sign.

21

Class 4 laser

Hazardous to the eyes and the skin during intrabeam and diffuse exposure. Potential fire hazard. Power level >500 mW. ANSI 'DANGER' sign

22

Aversion response time for visible light

0.25 seconds

23

Aversion response time for IR

10 seconds

24

one Watt is equal to

1 joule per second

25

Peak Power (Watts)

Energy/Time (Joules/second)

26

Irradiance (E)

E=Watts/((pi/4)(cm)^2))

27

Radiant exposure (H)

H=Joules/((pi/4)(cm^2))

28

Optical Density

OD=Log((E or H/MPE))