JAIPUR NATIONAL UNIVERSITY

SCHOOL PHARMACEUTICAL SCIENCES

Laser(Light Amplification by Stimulated Emission of

Radiation) vineeGupta

M.Pharma 2ndsem

Pharmecutics

JNU, jaipur

The LASER beam was invented by the physicist MAIMAN in 1960

One of the most influential technological achievements of the 20th century

Lasers are basically excited light waves

STIMULATED EMISSION (2)

Incident photon Incident

photon

Emitted photon

Excitedelectron

Unexcitedelectron

Before emission After emission

CHARACTERISTICS OF LASER LIGHT

MONOCHROMATIC

DIRECTIONAL

COHERENT

The combination of these three properties makes laser light focus 100 times better than ordinary light

INVERTED POPULATION

When a sizable population of electrons resides in upper levels, this condition is called a "population inversion“In order to obtain the coherent light from stimulated emission, two conditions must be satisfied:

1. The atoms must be excited to the higher state. That is, an inverted population is needed, one in which more atoms are in the upper state than in the lower one, so that emission of photons will dominate over absorption.

Unexcited system

1E

2E3E

Excited system

1E

2E3E

METASTABLE STATE

2. The higher state must be a metastable state – a state in which the electrons remain longer than usual so that the transition to the lower state occurs by stimulated emission rather than spontaneously.

Metastable state

Photon of energy 12 EE

1E

2E3E

Metastable system1E

2E3E

Stimulated emission

Incident photon

Emitted photon

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INCANDESCENT VS. LASER LIGHT

1. Many wavelengths

2. Multidirectional

3. Incoherent

1. Monochromatic

2. Directional

3. Coherent

Radio

Long Wavelength

Short Wavelength

Gamma Ray

X-ray Ultraviolet

Infrared Microwaves

Visible

ELECTROMAGNETIC SPECTRUM

Lasers operate in the ultraviolet, visible, and infrared.

Radio

LASER SPECTRUM

10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 1 10 102

LASERS

200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 10600

Ultraviolet Visible Near Infrared Far Infrared

Gamma Rays X-Rays Ultra- Visible Infrared Micro- Radar TV Radio violet waves waves waves waves

Wavelength (m)

Wavelength (nm)

Nd:YAG 1064

GaAs 905

HeNe 633

Ar488/515

CO2 10600

XeCl 308

KrF248

2wNd:YAG 532

Retinal Hazard Region

ArF193

Communication Diode 1550

Ruby 694

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Alexandrite 755

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LASER OUTPUTContinuous Output (CW) Pulsed Output (P)

                       

watt (W) - Unit of power or radiant flux (1 watt = 1 joule per second).

Joule (J) - A unit of energy

Energy (Q) The capacity for doing work. Energy content is commonly used to characterize the output from pulsed lasers and is generally expressed in Joules (J).

Irradiance (E) - Power per unit area, expressed in watts per square centimeter.

En

erg

y (W

atts

)

TimeE

ner

gy

(Jo

ule

s)Time

LASER can be considered to be a form of light amplifier,

behave according to the basic laws of light, characteristics:

- travels in straight lines with a constant velocity in space;

- it can be located inside the electromagnetic spectrum acc. to its wavelength or frequency;

- it present a particular chromatic purity;

- can be transmitted;

- can be reflected;

- can be refracted;

- can be absorbed;

- it has the capacity of transmitting energy without loss through the air

- the LASER can be used both as unitary impulses and under continuous form.

LASER COMPONENTS

ACTIVE MEDIUM

Solid (Crystal)Gas

Semiconductor (Diode)

Liquid (Dye)

EXCITATION MECHANISM

Optical ElectricalChemical

OPTICAL RESONATOR

HR Mirror andOutput Coupler

The Active Medium contains atoms which can emit light by stimulated emission.

The Excitation Mechanism is a source of energy to excite the atoms to the proper energy state.

The Optical Resonator reflects the laser beam through the active medium for amplification.

High ReflectanceMirror (HR)

Output CouplerMirror (OC)

ActiveMedium

Output Beam

Excitation Mechanis

m

Optical Resonator

the beam of light is reflected back and forth along the central tube, until the waves of light become coherent.

MECHANISM OF LASER EMISSIONABSORPTION

E1

E2

SPONTANEOUS EMISSION

STIMULATED EMISSION

CLASSIFICATION OF LASER ACC. TO PRODUCTION TECHNIQUE

1. Optically Pumped Solid-State Lasers

I. Ruby Laser

II. Rare Earth Ion Lasers

III. Nd: YAG Lasers.

IV. Nd: Glass Lasers

V. Tunable Solid-State lasers

2 Liquid (Dye) Lasers3 Gas Lasers4 Semiconductor Lasers5 Free Electron Lasers6 X-ray Lasers, and7 Chemical Lasers

TYPES OF MEDICAL LASERS, ACCORDING THE INTENSITY OF EMISSION

a) Power LASER – has a strong emission only used in surgery; used to cut, coagulate and

evaporate tissues they can replace the scalpel of the surgeon this are ,,Hot laser’’, it deliver power up to thousands

of watts, for removal of unhealthy tissue without damaging the healthy tissue that surrounds it.

b) Mild LASER – medium emission is used for treatment of deeper tissues c) Soft LASER – weak emission acts only at the surface (dermathology)

LASER HAZARD CLASSES

Lasers are classified according to the level of laser radiation that is accessible during normal operation.

CLASS 1 • Safe during normal use• Incapable of causing injury• Low power or enclosed beam

CLASS I Laser Product

Label not required

May be higher class duringmaintenance or service

Nd:YAG Laser Marker

CLASS 2

CLASS II LASER PRODUCT

Laser RadiationDo Not Stare Into Beam

Helium Neon Laser1 milliwatt max/cw

• Staring into beam is eye hazard• Eye protected by aversion response• Visible lasers only• CW maximum power 1 mW

Laser Scanners

CLASS 3R (Formerly 3a)

Small Beam

Expanded Beam

CLASS IIIa Laser Product

LASER RADIATION-AVOID DIRECT EYE EXPOSURE

ND:YAG 532nm5 milliwatts max/CW

• Aversion response may not provide adequate eye protection• CDRH(Center for Devices and Radiological

Health ) includes visible lasers only• ANSI includes invisible lasers• CW maximum power (visible) 5 mW

Laser Pointers

CLASS IIIa LASER PRODUCT

Laser Radiation-Do Not Stare Into Beam or ViewDirectly With Optical InstrumentsHelium Neon Laser

5 milliwatt max/cw

CLASS 3B

• Direct exposure to beam is eye hazard• Visible or invisible• CW maximum power 500 mW

CLASS IIIb Laser Product

LASER RADIATION-AVOID DIRECT EXPOSURE TO BEAM

2w ND:YAG Wavelength: 532 nmOutput Power 80 mW

DPSS Laser with cover removed

CLASS 4

CLASS IV Laser Product

VISIBLE LASER RADIATION-AVOID EYE OR SKIN EXPOSURE TO DIRECT OR SCATTERED RADIATION

2w Nd:YAGWavelength: 532 nmOutput Power 20 W

• Exposure to direct beam and scattered light is eye and skin hazard• Visible or invisible• CW power >0.5 W• Fire hazard

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M is for magnification.

A class 1M laser is class 1 unless magnifying optics are used.

A class 2M laser is class 2 unless magnifying optics are used.

M classes usually apply to expanded or diverging beams.

CLASS 1M & 2M

LASER

Condition 2Diverging Beam

LASER

Condition 1Expanded Beam

Class 1 Incapable of causing injury during normal operation

Class 1M Incapable of causing injury during normal operationunless collecting optics are used

Class 2 Visible lasers incapable of causing injury in 0.25 s.

Class 2M Visible lasers incapable of causing injury in 0.25 sunless collecting optics are used

Class 3R Marginally unsafe for intrabeam viewing; up to 5 times the class 2 limit for visible lasers or 5 times the class 1 limit for invisible lasers

Class 3B Eye hazard for intrabeam viewing, usually not an eye hazard for diffuse viewing

Class 4 Eye and skin hazard for both direct and scattered exposure

LASER CLASSIFICATION SUMMARY

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The Federal Laser Product Performance Standard (FLPPS)of the Center for Devices and Radiological Health (CDRH)

This is federal law and applies to the manufacture of lasers.

The American National Standard for Safe Use of Lasers (ANSI

Z136.1) This is a VOLUNTARY Standard that applies to the

use of lasers. “recognized by” :

The Occupational Safety and Health Administration (OSHA)

IEC 60825 International Standard

LASER SAFETY STANDARDS

MORE RECENTLY HAVE BEEN ADOPTED THE TERMS OF:

Low Level Laser Therapy (LLLT),Low Intensity Laser Therapy (LILT).LLLT devices are typically delivering 10mW -200mW (0.2 0.01 Watts).

LLLT WHEN APPLIED TO THE BODY TISSUES

The generation of heat perturb local electron orbits and the result/ mechanisms on the cell membrane

Initiate chemical change, Disrupt molecular bonds and Produce free radicals.

TRATAMENT BY LLLT

LLLT offer superior healing and pain relieving effects , especially in the early stages of acute injuries, and for chronic problems.

LLLT is a universal method of treating muscle, tendon, ligament, connective tissue, bone and skin tissue with one simple piece of equipment, however, the best results are achieved when it is used to complement other treatment modalities!

Importantly for athletes, LLLT is a non-invasive, drug-free modality that can be applied on competition day without risking disqualification by drug testing!

HOW DOES LASER WORK?

The LASER effect at the cellular level, in vivo situation, is not complete and it is not very well know ,

studies are conducted for the research of all this effects, and it is far away to be completed.

DOSE CALCULATIONS

Energy Density is measured in units of Joules per square centimeter (J/cm2).

a lot of apparatus offer '’on board'’ calculations of this dose

operator to make some simple calculations based on several considerations:

output power (Watts) irradiation area (cm2) time (seconds)

GENERALITY

Most authorities suggest that the ENERGY DENSITY per TREATMENT SESSION should generally reduce in the range of 0.1 - 12.0 J/cm2 despite the fact that there are some recommendations which go up to 30 J/cm2.

maximal dose of 4 J/cm2 should not be exceeded.

Lower doses should be applied to the more acute lesions which would appear to be more energy sensitive.

Treatment time between 4 and 12 minutes.

FEDERAL SAFETY REQUIREMENTS FOR CLASS 1 LASER SYSTEMS WITH ENCLOSED CLASS 3b AND 4

LASERS

Protective Housing prevents access to laser radiation above safe level.

Safety Interlocks terminate laser beam if protective housing in opened.

Only authorized personnel may operate laser with interlocks defeated.

Warning Labels alert personnel if opening the housing might expose a laser hazard.

Viewing Windows and Optics limit laser and collateral radiation to safe levels.

DEFINITION OF MPE

Maximum

Permissible

Exposure

The level of laser light to which a person may be exposed without risk of injury.

SUGGESTED SOP FORMAT

1. Introduction – Description of laserType and wavelength; Intended application & LocationAverage power or energy per pulsePulse duration and repetition rate for pulsed lasers

2. Hazards – List all hazards associated with laserEye and skin hazards from direct and diffuse exposuresElectrical hazardsLaser generated air contaminantsOther recognized hazards

3. Control Measures – List control measures for each hazardEyewear requirement, include wavelength and ODDescription of controlled area and entry controlsReference to equipment manualAlignment procedures (or guidelines)

4. Authorized Personnel

5. Emergency Procedures

CONTRAINDICATIONS OF LASER THERAPY ARE

Pregnancy treatment over the pregnant uterus could affect rapidly dividing cells,

Patients with chronic pain have reported increased tiredness for a brief period, and long-standing pain conditions may transiently increase.

Areas of impaired sensation. Infections increase the risk of spreading the

infection, Hemophilia,

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CONTROL MEASURES

Engineering Controls

Interlocks

Enclosed beam

Administrative Controls

Standard Operating Procedures (SOPs)

Training

Personnel Protective Equipment (PPE)

Eye protection

CDRH CLASS WARNING LABELS

CLASS II LASER PRODUCT

Laser RadiationDo Not Stare Into Beam

Helium Neon Laser1 milliwatt max/cw

CLASS IV Laser Product

VISIBLE LASER RADIATION-AVOID EYE OR SKIN EXPOSURE TO DIRECT OR SCATTERED RADIATION

Argon IonWavelength: 488/514 nmOutput Power 5 W

Class IIClass IIIa with expanded beam

Class IIIa with small beamClass IIIbClass IV

INTERNATIONAL LASERWARNING LABELS

Symbol and Border: BlackBackground: Yellow

Legend and Border: BlackBackground: Yellow

INVISIBLE LASER RADIATIONAVOID EYE OR SKIN EXPOSURE

TO DIRECT OR SCATTERED RADIATIONCLASS 4 LASER PRODUCT

WAVELENGTH 10,600 nmMAX LASER POWER 200 W

EN60825-1 1998

USES

In medicine to break up gallstones and kidney stones, to weld broken tissue (e.g. detached retina) to destroy cancerous and precancerous cells; at the same time,

the heat seal off capillaries, to remove plaque clogging human arteries.

used to measure blood cell diameter fibre-optic laser catheter is in the treatment of

bleeding

ulcers. can photocoagulate blood can also be used for dental treatment

In industry to drill tiny holes in hard materials, for welding and machining, for lining up equipment precisely, especially in

inaccessible places

In everyday life to be used as bar-code readers, to be used in compact disc players, to produce short pulses of light used in digital

communications, to produce holograms.

HOLOGRAPHY Holography is the production of holograms by the use of

laser. A hologram is a 3D image recorded in a special

photographic plate. The image appears to float in space and to move when

the viewer moves.

RESEARCH

used to measure the speed of light in a laboratory

CLASS 4 LASER

ND:YAG 1064 nm100 Watts Max. Average Power

VISIBLE and/ or INVISIBLE LASER RADIATION-AVOID EYE OR SKIN EXPOSURE TO DIRECT OR SCATTERED RADIATION.

Controlled Area Warning Sign

LABORATORY DOOR INTERLOCK

ENTRYWAY WARNING LIGHTS

Photos courtesy of

LASER PROTECTIVE BARRIERS

CURBS ON OPTICAL TABLE

BEAM CONTROL

LASER SAFETY EYEWEAR

EYEWEAR LABELS

All eyewear must be labeled with wavelength and optical density.

The person operating the laser always has the primary responsibility for all hazards

associated with laser use.

WHO HAS PRIMARY RESPONSIBLITY FOR LASER

SAFETY ANY TIME A CLASS 3B OR CLASS 4 LASER IS OPERATED?

CONCLUSION

Laser communication in space has long been a goal for NASA because it would enable data transmission rates that are 10 to 1,000 times higher than traditional radio waves.

While lasers and radio transmissions both travel at light-speed, lasers can pack more data. It's similar to moving from a dial-up Internet connection to broadband.Astronomers could use lasers like very accurate rulers to measure the movement of planets with unprecedented precision.With microwaves, we're limited to numbers like a meter or two in distance, whereas [lasers have] a potential for getting down into well beyond the centimeter range.

THANK YOU