This document discusses lasers and their applications. It begins by defining what a laser is, explaining that it produces coherent, monochromatic light in a single direction. It then covers the basic science of how lasers work through stimulated emission. Different types of lasers are described based on the lasing medium used. Medical applications are discussed in depth, including uses in surgery, dentistry, dermatology and more. Laser hair removal is explained as an example, describing how lasers target melanin in hair follicles to destroy them over multiple treatments. In summary, the document provides an overview of lasers, their functioning principles, types and important applications such as in medicine.

1. ‫بس‬‫الرحيم‬ ‫الرحمن‬ ‫هللا‬ ‫م‬
Al-Quds University
Faculty of Medicine
Medical Physics
Section 7
Laser and its applications
Student: Diaa Mohammad Sarahin
Instructor: Dr. Husain Alsamamra

2. Laser and its application
Laser enteredin manytechnological productsandit's consideredasanessential component
in CD players or in machines or dentist in cutting equipment and welding of iron or in the
measuringinstrumentsandotherfields. All of thesedevices use laser ,but what is Laser and
what makes the laser unique from other light sources. In this article we will explain
everything related to laser in a simple and clear .
Research Laboratory uses a laser beam
The word LASER namingof characters initial ideaforthe workof the laser and the following
sentence :
Light Amplification by Stimulated Emission of Radiation
The scientistAlbertEinsteinhaspredictedthe existence of the laser in 1917 and he put the
theoretical foundation for the process of Stimulated emission. first laser device Has been
designedinthe worldin1960 by T.H. Maimanusing a sapphire crystal and is known as Ruby
laser .
Laser production
If an atom supplied by a thermal energy or an energy from a light source or electric, some
of the electrons in the atom will move from orbit with a lower energy level to a higher
energy orbit and farther from the nucleus .
This idea is simplify to the previous process of absorption of energy in the atom, but is
considered the basis for the role of atom to produce the laser .
It is very important to obtain a laser Stir a large number of atoms, which photons are
emitted have the same wavelength (light-colored exact) .

3. Laser Light
Laser light differs from ordinary light which has the following characteristics:
1. Monochromatic light emitted, that has one wavelength, Wavelength determines
the color of the light output as well as its energy .
2. The lightemittedfromthe laser is coherent . In other words, the photons are all in
the same phase which makes the intensity of the light is great . so photons Do not
hide each other as a result of the phase difference between them .
3. Lightemittedhas one direction, Which the laser beam is a package of photons in a
straight path while ordinary light is scattered and spread across the space .
The responsible for these characteristics is the process of stimulated emission, while in
ordinary light the emission is spontaneous where each photon go out randomly with no
relation with other photons .
Types of laser
Solid-state laser : laser that produced by a material or mixture of solid stuffs like
ruby or mixture of neodymium-yttrium-aluminum, and its wavelength occurs in
Infrared " IR " region .
Gas laser : laser depends on gaseous material as " He , Ne , CO2 " and their
wavelengths occur in " IR " region .
Excimerlaser: laserthatusesNobel gasesas" Kr ,Ar " , andits wavelengthoccurs in
Ultraviolet " UV" region .
Dye laser: laserconsistof complicatedorganicsubstancesasdissolved rhodamine -
6G in alcoholic solution .
Semiconductor laser : sometimes called the diode laser depends on the
semiconductormaterial andit's characterizedbythe small size of the laser and little
powerconsumption,therefore isusedinmicroelectronicdevicessuch as CD devices
and laser printers .

4. Laser applications
 Industrial applications : such as measurements and alignment for Optical devices
Electricity lines , integrated circuit " IC " .
 Military applications : laser Used in correction, and used in remote detonation ,
uranium enrichment and nuclear fusion reaction .
 Scientific research applications : Spectroscopy , Laser (inertial) fusion, Very short
pulses (10-15 femtosec) , laser cooling of atoms , Study of the interaction of
electromagnetic radiation with matter .
 Special applications : Energy transport in space , Laser gyroscope , Fiber laser.
 Dailyapplications:
UsesFiled
Compact disc " CD "In House
Laser PrinterIn Work
Barcode ReaderIn Trade
FiberglassIn Communications
Exhibitions a three-dimensional imagingIn Entertainment

5.  Medical applications :
Laser enterinmedical applicationsand these applications divided either by type of
treatmentlike applicationsinsurgeryor in the field of dentistry or ophthalmology ,
dividedalsodepending on the type of laser used in medicine , such as laser carbon
dioxide or nitrogen laser or laser Alaximr, divided sometimes depending on the
nature of treatment applications such as surgery or welding or vascular diagnosis .
To understandthe applicationsof laser inmedicine must examine the relationship
between the laser and the different living cells . This relationship depends on the
characteristicsof the laser in terms of wavelength and intensity and shape when it
fell onthe bodyto be treated.If we considerthatenergylaser in the range of 1 watt
so we can by changing the wavelength control the nature of the relationship
between the laser and the living cells .
Laser effects in medical applications :
 Laser , whichworksinthe area of extreme ultraviolet kills living cells , such
as RNA and DNA .
 Laser , which works in the area of near ultraviolet radiation causes a
chemical reaction with the components of cells .
 Laser , which works in the area of visual ray causes thermal effects on the
cell because it absorbs the laser energy .
Medical fields that Laser enter in :
Eye Treatment, General Surgery, Ear, Nose and Throat, Dentistry, Dermatology,
Gastroenterology and colo-rectal, Plastic surgery, Gynecology, Urology, Oncology,
Orthopedics, Neurosurgery, Veterinary, Cardiovascular .
Before After

6. Hair removal ( Epilation)
Some of modernuses of laserspecially, Ruby laser or Alexandrite laser is to remove excess
hair unwanted . it's the only way which destroys the hair follicle without causing any skin
problemsandwithoutpainorsurgical intervention or hormone . Laser works by a quick red
pulses that destroys Excess hair follicles and without impact on the surrounding skin cells,
and alsowithouteffectonthe general bodyonthe shortor long term. Session of Ruby laser
does not take more than ten minutes to remove facial hair. As for the rest of the body still
takes relatively longer time . Laser eliminates all the hair follicles , which in the process of
full growth butdoesnot affectthe follicles , which in other stages of growth, so the patient
needsto3-6 sessions tobe eliminated85-90% of hair folliclesandthusnotappearing again .
The method of hair removal
Laser is a focused light radiation that penetrate to the skin and hair follicles, which these
follicles absorb .
Laser energy turns into heat which weakens the hair follicle without causing any internal
complications , and the skin is protected during the treatment ,through effective cooling
process by pumping soothing to the skin as the same speed of light .
This soothing works on cooling the upper layers of the skin providing people more
convenience,thishelpstoprotect the skin during treatment and at the same time helps to
deliver greater amounts of light reaching to the ends of the follicle to destroy it .
Laser decreases hair density after several sessions , The effectiveness of this method
depends onthe densityof hairinthe area to be treatedandthe degree of hairgrowth,more
the hair thickerresultsisbetter.Therefore the treatmentismore effective withpeople who
have black hair or dark brown because it contains a higher proportion of melanin , which
absorbs light with large percent .
people whohave blondhairare needmore sessionstoreachthe desiredresult . Taking into
account, that white hair is not affected by laser because it does not have pigment stuff .
As a result, Epilation byLaserisconsidered an efficient and long-term method, that reduce
time and efforts compare with traditional methods .
References:
http://ar.wikipedia.org
http://hazemsakeek.net
http://www.tbeeb.net