therapeutic effect and types of laser

1. IRAM ANWAR

2. TYPES OF LASER
1. Solid State Laser
2. Gas Lasers
3. Dye lasers
4. Semiconductor lasers,

4. 1. Solid State Lasers:
Solid state lasers have lasing material distributed in a solid matrix, e.g., the
ruby or neodymium-YAG (yttrium aluminum garnet) lasers. The neodymium-
YAG laser emits infrared light at 1.064 micrometers.
Solid state lasers use high density solid media as active laser materials. Ions
of transition elements, particularly rare earth elements (Nd, Yb, Er, Ho etc.) or
transition metals (Cr, Ti etc.) are used most commonly as dopants as well as
glasses from silicate (SiO2) and phosphate classes.
• Advantages No chance is of wasting material in the active medium because
here material used is in solid form not in gas form, where this occurs. Both
continuous and pulsed output is possible from solid state lasers. Solid state
lasers have high Construction is comparatively simple. Output power
ranging from very low value of about 0.04 watts to high value of about 600
watts. Cost of solid state lasers is economical.
• Disadvantages Efficiency of solid state laser is very low as compared to
CO2 lasers. Great disadvantage of solid state lasers is the divergence. Output
power is also not very high as in CO2 lasers. Due to thermal lasing in solid
state lasers, the power loss occurs when the rod gets too hot

6. 2.Gas lasers: Gas lasers (helium and helium-neon, HeNe, are the most common
gas lasers) have a primary output of a visible red light. CO2 lasers emit energy in
the far-infrared, 10.6 micrometers, and are used for cutting hard materials.
General properties Solid state lasers use high density solid media as active laser
materials. Ions of transition elements, particularly rare earth elements (Nd, Yb,
Er, Ho etc.) or transition metals (Cr, Ti etc.) are used most commonly as dopants.
Host materials include crystals like sapphire (Al2O3), YLF (YLiF4), YAG
(Y3Al5O12), LISAF (LiSrAlF6), LICAF (LiCaAlF6), as well as glasses from
silicate (SiO2) and phosphate (P2O5) classes.
Advantages No chance is of wasting material in the active medium because here
material used is in solid form not in gas form, where this occurs. Both continuous
and pulsed output is possible from solid state lasers. Solid state lasers have high
Construction is comparatively simple. Output power ranging from very low value
of about 0.04 watts to high value of about 600 watts.
Disadvantages Efficiency of solid state laser is very low as compared to CO2
lasers. Great disadvantage of solid state lasers is the divergence. Output power is
also not very high as in CO2 lasers. Due to thermal lasing in solid state lasers, the
power loss occurs when the rod gets too hot.

7. Dye laser

8. 3.Dye lasers: Dye lasers use complex organic dyes like rhodamine 6G in
liquid solution or suspension as lasing media. They are tunable over a broad range
of wave lengths.
Dye Laser (A Liquid Laser)Liquid lasers are those lasers which uses liquid as an
active medium. In dye laser the liquid material called dye (for example
rhodamine B, sodium fluoresein and rhodamie 6G) uses as an active medium,
which causes to produce laser light. The dye lasers produce output whose
wavelengths are in the visible, ultra violet and near infrared spectrum.
Advantages of Dye Lasers
It is available in visible form (also in non-visible) Range of wavelengths can be
produced by the using dye lasers. Beam diameter is very less. Its beam divergence
(0.8 milli radians to 2 milli radians) is also less from many lasers beam
divergence. Construction of dye laser is not so complex. Having the greater
efficiency 25%. High output power is also possible with dye lasers
Disadvantages of Dye Lasers
Cost of dye lasers is very high.To tune at one frequency, the laser uses
birefringent element or filter making it more costly. In dye lasers it is very
difficult to determine the element that actually lases because dye has complex
chemical formula
.

10. 4.Semiconductor lasers: Semiconductor lasers, sometimes called diode lasers,
are not solid-state lasers. These electronic devices are generally very small and use
low power.
The semiconductor laser is very small in size and appearance.It is similar to a
transistor and has the operation like LED but the output beam has the characteristics
of laser light.The material which often used in semiconductor laser is the gallium
Arsenide, therefore semiconductor laser is sometimes known as Gallium Arsenide
Laser. It is also called Injection Laser.
Advantages of Semiconductor Lasers Smaller size and appearance make them
good choice for many applications. From cost point of view the semiconductor lasers
are economical. Semiconductor lasers have high efficiency. The low power
consumption is also its great advantage.
Disadvantages of Semiconductor Lasers Semiconductor laser is greatly dependent
on temperature. The temperature affects greatly the output of the laser. The lasing
medium of semiconductor lasers is too short and rectangular so the output beam
profile has an unusual shape. Beam divergence is much greater from 125 to 400 milli
radians as compared to all other lasers.