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  • Light and its nature have caused a lot of ink to flow during these last decades. Its dual behavior is partly explained by (1)Double-slit experiment of Thomas Young - who represents the photon’s motion as a wave - and also by (2)the Photoelectric effect in which the photon is considered as a particle. A Revolution: SALEH THEORY solves this ambiguity and this difficulty presenting a three-dimensional trajectory for the photon's motion and a new formula to calculate its energy. More information on
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  • Thank you.Hopefully to mention PDT (Photodynamic Therapy).
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  1. 1. JAIPUR NATIONAL UNIVERSITY SCHOOL PHARMACEUTICAL SCIENCES Laser (Light Amplification by Stimulated Emission of Radiation) vineeGupta M.Pharma 2ndsem Pharmecutics JNU, jaipur
  2. 2. 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
  3. 3. STIMULATED EMISSION (2) Incident photon Incident photon Emitted photon Excited electron Unexcited electron Before emission After emission
  4. 4. CHARACTERISTICS OF LASER LIGHT MONOCHROMATIC DIRECTIONAL COHERENT The combination of these three properties makes laser light focus 100 times better than ordinary light
  5. 5. 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 2E 3E Excited system 1E 2E 3E
  6. 6. 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 2E 3E Metastable system 1E 2E 3E Stimulated emission Incident photon Emitted photon
  7. 7. 7 INCANDESCENT VS. LASER LIGHT 1. Many wavelengths 2. Multidirectional 3. Incoherent 1. Monochromatic 2. Directional 3. Coherent
  8. 8. Radio Long WavelengthShort Wavelength Gamma Ray X-ray Ultraviolet Infrared Microwaves Visible ELECTROMAGNETIC SPECTRUM Lasers operate in the ultraviolet, visible, and infrared. Radio
  9. 9. 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 Ar 488/515 CO2 10600 XeCl 308 KrF 248 2w Nd:YAG 532 Retinal Hazard Region ArF 193 Communication Diode 1550 Ruby 694 Alexandrite 755
  10. 10. 10 LASER OUTPUT Continuous 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. Energy(Watts) Time Energy(Joules) Time
  11. 11.  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.
  12. 12. LASER COMPONENTS ACTIVE MEDIUM Solid (Crystal) Gas Semiconductor (Diode) Liquid (Dye) EXCITATION MECHANISM Optical Electrical Chemical OPTICAL RESONATOR HR Mirror and Output 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 Reflectance Mirror (HR) Output Coupler Mirror (OC) Active Medium Output Beam Excitation Mechanism Optical Resonator
  13. 13.  the beam of light is reflected back and forth along the central tube, until the waves of light become coherent.
  17. 17. 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
  18. 18. 2 Liquid (Dye) Lasers 3 Gas Lasers 4 Semiconductor Lasers 5 Free Electron Lasers 6 X-ray Lasers, and 7 Chemical Lasers
  19. 19. 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)
  20. 20. LASER HAZARD CLASSES Lasers are classified according to the level of laser radiation that is accessible during normal operation.
  21. 21. 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 during maintenance or service Nd:YAG Laser Marker
  22. 22. CLASS 2 CLASS II LASER PRODUCT Laser Radiation Do Not Stare Into Beam Helium Neon Laser 1 milliwatt max/cw • Staring into beam is eye hazard • Eye protected by aversion response • Visible lasers only • CW maximum power 1 mW Laser Scanners
  23. 23. CLASS 3R (Formerly 3a) Small Beam Expanded Beam CLASS IIIa Laser Product LASER RADIATION- AVOID DIRECT EYE EXPOSURE ND:YAG 532nm 5 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 View Directly With Optical Instruments Helium Neon Laser 5 milliwatt max/cw
  24. 24. 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 nm Output Power 80 mW DPSS Laser with cover removed
  25. 25. CLASS 4 CLASS IV Laser Product VISIBLE LASER RADIATION- AVOID EYE OR SKIN EXPOSURE TO DIRECT OR SCATTERED RADIATION 2w Nd:YAG Wavelength: 532 nm Output 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
  26. 26. 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 Condition 2 Diverging Beam Condition 1 Expanded Beam
  27. 27. Class 1 Incapable of causing injury during normal operation Class 1M Incapable of causing injury during normal operation unless 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 s unless 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
  28. 28.  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
  29. 29. 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).
  30. 30. 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.
  31. 31. 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!
  32. 32. 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.
  33. 33. 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)
  34. 34. 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.
  35. 35. 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.
  36. 36. DEFINITION OF MPE Maximum Permissible Exposure The level of laser light to which a person may be exposed without risk of injury.
  37. 37. SUGGESTED SOP FORMAT 1. Introduction – Description of laser Type and wavelength; Intended application & Location Average power or energy per pulse Pulse duration and repetition rate for pulsed lasers 2. Hazards – List all hazards associated with laser Eye and skin hazards from direct and diffuse exposures Electrical hazards Laser generated air contaminants Other recognized hazards 3. Control Measures – List control measures for each hazard Eyewear requirement, include wavelength and OD Description of controlled area and entry controls Reference to equipment manual Alignment procedures (or guidelines) 4. Authorized Personnel 5. Emergency Procedures
  38. 38. 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,
  39. 39. 39 CONTROL MEASURES Engineering Controls  Interlocks  Enclosed beam Administrative Controls  Standard Operating Procedures (SOPs)  Training Personnel Protective Equipment (PPE)  Eye protection
  40. 40. CDRH CLASS WARNING LABELS CLASS II LASER PRODUCT Laser Radiation Do Not Stare Into Beam Helium Neon Laser 1 milliwatt max/cw CLASS IV Laser Product VISIBLE LASER RADIATION- AVOID EYE OR SKIN EXPOSURE TO DIRECT OR SCATTERED RADIATION Argon Ion Wavelength: 488/514 nm Output Power 5 W Class II Class IIIa with expanded beam Class IIIa with small beam Class IIIb Class IV
  42. 42. 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
  43. 43. In industry  to drill tiny holes in hard materials,  for welding and machining,  for lining up equipment precisely, especially in inaccessible places
  44. 44.  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.
  45. 45. 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.
  46. 46. RESEARCH  used to measure the speed of light in a laboratory
  50. 50. Photos courtesy of LASER PROTECTIVE BARRIERS
  52. 52. BEAM CONTROL
  54. 54. EYEWEAR LABELS All eyewear must be labeled with wavelength and optical density.
  55. 55. 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?
  56. 56. 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.
  57. 57. THANK YOU