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Laser Laser: “light amplification by stimulated emission of radiation. A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow. A laser differs from other sources of light in that it emits light coherently. Spatial coherence allows a laser to be focused to a tight spot, enabling applications such as laser cutting and lithography. Spatial coherence also allows a laser beam to stay narrow over great distances (collimation), enabling applications such as laser pointers. Elements of laser production: 1. Pumping: is the energy source which supply the lasing medium with energy. Three source of energy: a. optical pumping. b. electrical pumping . c. chemical pumping. 2. Lasing medium: It is the material responsible to generate laser and possess the ability of population inversion, may be solid, liquid or gases. 3. Resonator or optical cavity: Tube or cavity contain medium and two parallel mirrors one in front the other. Components of a typical Laser: 1. 2. 3. 5. Medium. Laser pumping energy. Mirrors (3+4). Laser beam. The medium is a material with properties that allow it to amplify light by way of stimulated emission. Light of a specific wavelength that passes through the medium is amplified (increases in power). For the medium to amplify light, it needs to be supplied with energy in a process called pumping. The energy is typically supplied as an electric current or as light at a different wavelength. Pump light may be provided by a flash lamp or by another laser. Characters of Laser: Lasers are distinguished from other light sources by”: 1. Their coherence. Spatial coherence is typically expressed through the output being a narrow beam, which is diffraction-limited. Laser beams can be focused to very tiny spots, achieving a very high irradiance, or they can have very low divergence in order to concentrate their power at a great distance. 2. Monochromatic light. 3. High intensity light. 4. Laser in area of Ultraviolet light, visible light, infrared light. Continuous and pulsed laser: A laser can be classified as operating in either continuous or pulsed mode, depending on whether the power output is essentially continuous over time or whether its output takes the form of pulses of light on one or another time scale. Classification of Laser: First: According to the condition of active medium: A. Gas lasers: Helium–neon laser (He, Ne), carbon dioxide (CO ) lasers. 2 B. Liquid lasers: As examples, organic dye and Rhodamine. C. Solid-state lasers : for example, the first working laser was a ruby laser. Second: According to the types of radiation: A.Continuous laser. B. Pulsed laser. Third: According to the nature of activity: A. Surgical laser. B. Stimulating laser. Fourth: According to the nature of pumping: A. Electrical. B. Light. C. Chemical. . • • • • • • • • • Properties of laser surgery 1. Short stay in hospital. 2. Rapid operation. 3. Painless. 4. Low blemish. 5. Less hemorrhage and good control of bleeding. 6. Less infection. 7. Ablation of deep lesion. 8. Laser intensity was regulated to performed coagulation, vaporization and cutting. Laser therapy is used in many procedures. It may be used to: • shrink or destroy tumors, polyps, or precancerous growths • relieve symptoms of cancer • remove kidney stones • remove part of the prostate • repair a detached retina • improve vision (“laser eye surgery”) • Lasers can have a cauterizing (sealing) effect. • They may be used to seal: nerve endings, to reduce pain after surgery. Blood vessels, to help prevent blood loss. Lymph vessels, to reduce swelling and limit spread of tumor cells. • • Laser therapy can be utilized to: • • • • • Reduce inflammation Increase tendon and wound strength Reduce pain Increase lymphatic drainage Improve healing time • • • • • Relax tight muscles Increase mobility Reduce swelling Reduce scarring Speed bone repair Indications of continuous and pulsed modes of operation: 1. Cosmetic surgery (to remove tattoos, scars, stretch marks, sunspots, wrinkles, birthmarks) 2. Refractive eye surgery (to reshape the cornea in order to correct or improve vision) 3. Dental procedures (such as endodontic/periodontic procedures, tooth whitening, and oral surgery) 4. General surgery (such as tumor removal, cataract removal, breast surgery, plastic surgery and most other surgical procedures) CONTRAINDICATIONS 1. Pregnancy. 2. Patients with cancer. 3. Patients with pacemakers. 4. Directly looking into the light. 5. Growth plates in children. 6. Over cardiac region & Vagus nerve. 7. Over & around thyroid gland & endocrine glands. 8.Patients who have been pre-treated with one or more photo- sensitizers. 9. Organ transplantation: There is a possibility that the laser's positive effects on immune systems could compromise the immune suppression, which is critical to successful.