CH13 - Low-Power Laser

coherence

property of identical phase and time relationship; all photons of laser light are the same wavelength

collimation

there is minimal divergence of the photons; photons move in a parallel fashion, concentrating a beam of light

continuous wave

an uninterrupted opposed to pulsed beam of laser light

direct effect

the tissue response that occurs from energy absorption

divergence

the bending of light rays away from each other; the spreading of light

frequency

the number of cycles or pulses per second

indirect effect

a decreased response that occurs in deeper tissues

laser

a device that concentrates high energies into a narrow beam of coherent, monochromatic light

monochromaticity

the condition that occurs when a light source produces a single color or wavelength

photon

the basic unit of light; a packet or quanta of light energy

stimulated emission

occurs when a photon interacts with an atom already in a high energy state and decay of the atomic system occurs, releasing two photons

wavelength

the distance from peak to the same point on the next peak of an electromagnetic or acoustic wave

_____ lasers deliver a characteristic red beam with a wavelength of 632.8 nm; delivered in a continuous wave and has direct penetration of 2-5 mm and an indirect penetration of 10-15 mm.

HeNe

_____ lasers are invisible and have a wavelength of 904 nm; delivered in a pulse mode and have an average power output of 0.4 mW; has a direct penetration of 1-2 cm and an indirect penetration of 5 cm.

GaAs

T/F: AN atom containing more energy than normal is considered to be in an excited state.

T

T/F: HeNe and AuAg lasers are the most common.

F

T/F: Tissue responses occuring from absorption of the laser are direct effects.

T

Which of the following is NOT a property of lasers?

divergence

_____ lasers may be used for wound healing and pain management.

low-power

Wounds treated with low-power lasers were shown to have what?

both of these

How are lasers thought to influence the inflammatory process?

decrease prostaglandin production

What type of laser application technique consists of holding the applicator over each square cm for the appropriate period of time?

gridding

Which of the following is a contrainication for low-power lasers?

cancerous tumors

What energy density range is used in therapeutic applications?

0.05-4 J/cm2

What does laser stand for?

light amplification for the stimulated emission of radiation

What lasers are used in medical treatment?

Class I and II