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Flashcards in LASER Deck (51)
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1

Light Amplification by Stimulated Emission of Radiation

Photon that hits atom that is already excited
This creates radiation effect

2

History of LASER: 1917

1917 Einstein - concept of stimulated emission of radiation

3

Biophysical father of LASER

Albert Einstein

4

History of LASER: 1954

Shawlow, Townes, Basoc and Prochorov
MASER
1st stimulated emission device

5

History of LASER: 1960`

Javan and Maiman
Ruby LASER - maiman
He-Ne LASER - javan
Visible portion of em spectrum

6

History of LASER: 1962

White et al
Cold LASER
Indigoviolet portion of roygbiv of light

7

History of LASER: 1960-1970

endre mester
Low level LASER diode type
Non thermal effects of LASER
Therapeutic father of LLLT
Was only used by doctors

8

History of LASER: 2002

low intensity laser in rehabilitation

9

On EM spectrum, it is close to ---- and ------

infrared and visible

10

properties of laser

Monochromatic : single frequency and wavelength making one color
Coherent : moves in one direction
Collimated : multiple wavelengths of radiation move parallel to each other

11

LASER produces ---- intensity light in ---- area/s

high, one

12

LASER physical components (gaseous and photodiode)

active medium (lasing agent); helium-neon; gallium arsenide, gallium-aluminum arsenide;

resonance chamber; sealed glass cylinder; diode p=n junction gap

power source; electrical; electrical

13

spontaneous emission

Absorption: When you plug the machine, the electrons move to higher energy shells

Emission: moves inwards to lower energy shell, creates radiation

Made of various wavelengths, therefore not monochromatic

14

stimulated emission is made of --- wavelengths, therefore you make a -----

Made of similar wavelengths, therefore you make a laser

15

longer wavelength = ---- frequency = ------ penetration

lower frequency, deeper penetration

16

red light vs violet light

violet = shorter wavelength

red = longer wavelength

17

red light penetration

600-700 nm

18

Helium-neon LASER penetration

632.8 nm

19

Ruby LASER penetration

694.3 nm

20

gallium aluminum arsenide LASER penetration

860-780 nm

21

gallium arsenide laser penetration

904-910 nm

22

power (mW)

rate of energy flow

23

power density (mW/cm2)

amount of power per unit area
maximum of 100 mW/cm2

24

class 1

power: <0.5 mW

no hazard

25

class 1M

power: <0.5 mW

no hazard because of large diameter beam or less-divergent beam

26

class 2

power: < 1 mW

safe for momentary viewing

provokes blink reflex

27

class 3A

<5 mW

Laser pointers; eye hazard with prolonged exposure

28

class 3B

<500 mW

for therapy; permanent eye damage with brief exposure, viewing of siffused beam reflected from skin is safe; minor burns with long exposure

29

class 4

>500 mW

surgical and industrial cutting laser

permanent eye damage

serious skin burns

burns clothing

30

photobiomodulation

light modulates biological processes

enhances cellular function