1. L ight A mplification by S timulated E mission of R adiation  LASERS are ELECTROMAGNETIC WAVE AMPLIFIERS

2. MONOCHROMATICITY  1. MONOCHROMATICITY – only one wavelength with a defined frequency. IDENTICAL  When a laser light entering a prism would be IDENTICAL on exit, because of MONOCHROMATICITY.

3. PEAKS & TROUGHS (TEMPORAL COHERENCE) (SPATIAL COHERENCE)  That is all the PEAKS & TROUGHS of the electrical & magnetic fields occurs at the same time (TEMPORAL COHERENCE) & travel in the same direction (SPATIAL COHERENCE).

4. parallelism  It refers to the relative parallelism of the laser beam. greater the concentration of energy  The more parallel the laser beam the greater the concentration of energy in a localized area. very low divergence property  The laser light has very low divergence property, so it does not tend to spread out.

5. Quantum theory (Stable / Ground / Lower State) 1. According to Quantum theory – electrons can only occupy certain energy levels or shells around the nucleus. (Stable / Ground / Lower State) additional energy (Excited / Unstable state) 2. If the atom is given additional energy say by heating, these outer electrons can be made to occupy higher energy levels. (Excited / Unstable state) 3. Spontaneous emission occurs. The excited state returns to a lower energy state, emitting the excess energy as a photon, or quanta of light.

6. Stable atom is given extra energy by heating Electron has a new Energy Level (excited) but unstable. Spontaneous emission, of photon, back to a lower energy level.

7. CASCADE / AVALANCHE EFFCET.  Since there are many more of electrons, there is further stimulated emission of photons causing a CASCADE / AVALANCHE EFFCET.  [(i.e.) One photon releasing another identical one photon, then these two stimulating two more & so on]  Population Inversion  Population Inversion – Having more atoms in the upper energy state than the lower energy state.

8. cylindrical tube low pressure  It consists of a cylindrical tube containing these gases at low pressure & surrounded by a flash gun / electrical supply. polished fully polished partially polished  Inside the tube it is polished for the reflection to occur (One end of the tube fully polished & the other end partially polished ) & so the molecules reverberate the walls in a highly agitated state, building energy.

9. BURSTS laser beam optic fiber beam applicator or probe  When the critical level is reached, the flow of energy literally BURSTS through the partially polished front end of the tube giving out the laser beam which is channeled along an optic fiber to the beam applicator or probe for treatment. visible red region at 632.8nm. The helium – neon lasers give radiation in the visible red region at 632.8nm.

11.  1. Helium – neon laser – Superficial benefit.  2. Gallium Aluminium Arsenide ( GaAs) – Deep benefit.  810 – 850nm – At near infrared wavelength

12. EPIDERMIS.  1. Helium – Neon Laser – up to EPIDERMIS.  (2 – 5mm depth)- Direct effect  (8 – 1omm depth) – Indirect effect EPIDERMIS & DERMIS  2. GaAs – up to EPIDERMIS & DERMIS  (1 – 2 cms depth)- Direct effect  (Up to 5 cms depth) – Indirect effect  This is selected for more deeper structures to treat, like – sprain, strain & contusion.

14.  The intensity of laser used in physiotherapy treatment range from 1mWcm¯² to 50mWcm¯². very low power & Intensity.  It is relatively very low power & Intensity. 3mm  The beam diameter is about 3mm which is used clinically.

15.  1. Heat Production – Reversible process  2. Dehydration – Reversible process  3. Coagulation of proteins, Thermolysis & Evaporation  3. Coagulation of proteins, Thermolysis & Evaporation SHOULD NOT OCCUR with the laser dosage.

16.  R eflected  A bsorbed  T ransmitted (Penetration)

17.  an acceleration in collagen synthesis,  enhancing cellular metabolism,  a decrease in microorganisms,  an increase in vascularization,  increases in fibroblastic proliferation,  enhances the synthesis of nucleic acids and cell division,  increased phagocytosis,  A decrease in prostaglandin (PGE 2 ),  decreased sensory nerve conduction velocity,

18.  Tissue / Wound Healing Increase in Collagen formation, Vasodilatation & DNA Synthesis. Additional factors involved are – Increase in Collagen formation, Vasodilatation & DNA Synthesis.  Pain Reduction – Both Acute & Chronic  Painful Soft tissue Injuries ( of swelling) edema

19.  Musculoskeletal Conditions  Swelling of Joints  Neurogenic pain states  Myofascial pain  Post traumatic joint disorders & Burns

20.  1. Cancer Tissue  2. Pregnant Uterus  3. Hemorrhage  4. Infected tissue  5. Epileptic  6. Cardiac patients  7. Pacemakers

21.  1. Eyes shiny surfaces  2. Avoid reflecting the laser beam from shiny surfaces CONTACT with the skin  3. Only switch ON the laser when the applicator is in CONTACT with the skin protective goggles  4. Use the appropriate protective goggles.

22.  1. Treatment is applied to the skin by a HAND – HELD APPARATUS. MAXIMUM  2. Direct application to the skin ensures MAXIMUM transfer of laser energy. GOGGLES  3. Need to wear the GOGGLES ALCOHOL.  4. The treatment surface is cleaned with ALCOHOL.

23. contact with the tissues.  5. It is important to maintain the laser applicator in contact with the tissues. RIGHT ANGLES  6. The laser beam is applied at RIGHT ANGLES.  TENDERNESS / PAIN.  7. The applicator contact should not provoke TENDERNESS / PAIN.

24. SUPERFICIAL CONDITIONS – Wounds, Ulcers & Skin conditions. 8. Visible red light laser (HeNe) is recommended for SUPERFICIAL CONDITIONS – Wounds, Ulcers & Skin conditions. DEEPER MUSCULOSKELETAL STRUCTURES (GaAs) 9. Infrared laser is for DEEPER MUSCULOSKELETAL STRUCTURES (GaAs) 10. Low power (BioStimulative) lasers provide NO SENSATION to the patient.

25.  1. Type of Laser – HeNe, GaAlAs  2. Wavelength of Laser  3. Power of Laser  4. Size of the treatment area  5. Exposure time

26.  1. The amount of energy delivered to the patient is measured in JOULES PER CENTIMETER SQUARE. J/Cm².  It can be calculated by a formula consisting of ( The time of exposure, The power of the laser & the size of the area)

27.  Mean power = 10mw  Treatment Area = 0.125cm²  Time of exposure = 50sec  10mw/0.125cm² = 80mw/cm²  Energy Density = 80mw/cm² x 50sec = 4000mJ/cm² = 4J/cm²

28. 1 to 10J/cm²  The usual ranges are from 1 to 10J/cm²  Dose as low as 0.5J/cm²  Dose as high up to 32J/cm²  The therapeutic laser range from 0.5J/cm² & 4J/cm²

29.  It is generally recommended that the LOW PULSE FREQUENCIES & LONG PULSE DURATIONS – ACUTE CONDITION.  HIGHER PULSE FREQUENCY & SHORT PULSE DURATION – CHRONIC CONDITIONS  Note:- 1. Low power laser DOES NOT PRODUCE THERMAL RESPONSE. 2. The power of laser is preset within the device along with the wavelength.

30.  1. Direct Contact Application  2. Scanning Technique  3. Spot Technique / Gridding  4. Acupuncture point Application