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Laser basics[26239].pptx
- 1. Basic dental Laser knowledge Dr.Hanaa Mohammed El Shenawy .. Professor of Laser applications in Dentistry, in oral surgery& medicine department, National research Center Cairo PhD degree in Medical and Biological Application of Laser Science
- 2. Introduction Historical Perspective Fundamentals ofdental lasers Laser Physics Lasers in Dentistry Endodontics ,Operative & Aesthetic Dentistry Dental laser safety
- 3. Light Amplification by S timulated Emissionof Radiation
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- 5. Electromagnetic spectrum Generally,EM radiation is classified by wavelength into electrical energy, radio, microwave, infrared, the visible region we perceive as light, ultraviolet, X-rays and gamma rays. The behavior of EM radiation depends on its wavelength. Higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths. When EM radiation interacts with single atoms and molecules, its behavior depends on the amount of energy per quantum it carries.
- 6. A laser isa device that transforms light of various frequencies into a chromatic radiation in the visible, infrared, and ultraviolet regions with all the waves in phase capable of mobilizing immense heat and power when focused at close range
- 7. L.A.S.E.R The solution thatis looking for the problem Lasers can be ... • based on solid, liquid, or gaseous media • big or small, expensive or cheap • high or low power, • pulsed or continuous (CW) • at wavelengths anywhere from the far IR to the X- ray region
- 12. Laser Physics Theelectron may be in either of the two energy levels, thus:
- 13. Laser Physics Ifthe electron is in the higher level it may fall down into the lower level. In its doing this it must give up an amount of energy equal to the energy difference between the two levels. Now we finally get to lasers. L.A.S.E.R. which can cause stimulated emission in two more atoms to give four photons , and so on.
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- 15. Laser consists ofa lasing medium contained with an optical cavity, with an external energy source to maintain a population inversion so that stimulated emission of a specific wavelength can occur, producing monochromatic, collimated and coherent beam of light
- 18. All dentallasers have emission wave lengths of 0.5μm (500 nm) to 10.6μm (10,600 nm) Within the visible or invisible infrared non-ionizing EM range & emit thermal radiation The dividing line between ionizing and non-ionizing portion is on the junction of ultraviolet and visible violet light
- 19. Active medium– Gas, liquid or solid Contained in glass or ceramic tubes Energy – Electric current Mirrors are added to each end to increase the back and forth movement of photons Thus increasing the stimulation of emission of radiation
- 20. Laser Delivery Systems Coherent, Collimated beam of laser light must be delivered to the target tissue Two delivery systems that are employed Hollow Waveguide or Tube Glass fiber optic cable
- 21. Flexible Hollow Waveguide(Tube) Has an interior finish mirror Laser energy is reflected along this tube and exits through a hand piece Strikes the tissue in a non-contact manner An accessory tip of sapphire or hollow metal can be connected
- 22. Glass Fiber opticcable More flexible than waveguide Less weight and less resistance in movement Smaller diameter (200-600 μm) Glass component is encased in a resilient sheath Fragile & can’t be bent in sharp angles Used in contact and non-contact mode
- 23. Advantages Thinner & flexible Highercarrying capacity Less energy degradation Low power consumption Non – inflammable Light weight
- 24. Laser Emission Modes Dental lasers can emit light energy in 2 modalities Constant ON Pulsed ON/OFF In Constant or Continuous Wave, the beam is emitted at one power In Gated Pulse Mode, there are periodic alterations of laser energy (Blinking light)
- 25. This isachieved by the opening and closing of a mechanical shutter in front of the beam path of a continuous wave emission All surgical lasers that operate in continuous wave have this gated pulse feature Third mode is termed Free running pulsed mode or True Pulsed In this large peak of energy of laser light is emitted for a very short time
- 26. Laser – TissueInteraction Laser light has four different interactions with the target tissue Amount of energy absorbed by the tissue depends on the tissue characteristics such as pigmentation and water content
- 27. •Absorbed by tissues andresults and light energy is converted to thermal energy •Light travels in different directions, absorbed over a greater surface area •Causes less thermal effect • Light transfers to tissue without any interaction & injury • Little or no absorption • No thermal effect on Tissue Reflection Transmission Absorption Scattering
- 29. At lowtemperatures below 100°C, the thermal effects denature proteins and produce hemolysis They cause coagulation & shrinkage Above 400°C, carbonization of organic materials occurs with onset of some inorganic materials Between 400°C & 1200°C, inorganic constituents melt, re-crystallize or vaporize
- 30. Tissue Feature Hemoglobin Absorbedby Blue & Green WL Melanin Absorbed by short wavelengths Hydroxyapatite Absorbed by a wide range of WL Dental structures have different amount of water content, Enamel being the least followed by Dentin, Bone, Calculus, Caries and Soft tissue Dental lasers have a Photothermal effect
- 31. In general, shorterWL (500-1000 nm) are well absorbed in pigmented tissues and blood elements Longer WL are more interactive with water and Hydroxyapatite Co2 (10,600 nm) is well absorbed by water and has the highest affinity for Hydroxyapatite
- 32. What does theOperator control? Level of applied power (Power Density) Total energy to be delivered (Energy density) Rate & Duration of exposure (Pulse Repetition) Mode of energy delivery
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- 34. Common Laser typesUsed in Dentistry
- 35. Classifications: Lasers arenamed according to: Active medium Wavelength Delivery systems Emission modes Tissue absorption Clinical Application
- 36. Classifications: I. Based onActive Medium a) Solid State b) Gas c) Semiconductors d) Excimer e) Dye II. Mode of action a) Contact mode (focused or defocused) - Ho:YAG ; Nd: YAG b) Non-contact mode (focused or defocused) - CO2
- 37. III. Based asapplication a) Soft tissue laser - Argon, Co2, diode; Nd:YAG. b) Hard tissue laser - Er : YAG c) Resin curing laser - Argon IV. Based on Level of energy emission: a) Soft lasers (Low level energy): He-Neon; Ga-Arsenide. b) Hard lasers (High level energy): Er:YAG laser ; Nd: YAG laser.
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- 39. Argon Active mediumis Argon gas Fiber optically delivered Continuous wave & Gated Pulsed modes Only laser whose light is in the visible spectrum 2 wavelengths are used: 488 nm (Blue) 514 nm (Blue-Green)
- 40. 488 nmemission is used to activate camphoroquinone in composite resins The beam divergence of this blue light is used in non-contact mode, produces excessive amount of photons thus providing curing energy More strength in cured resin when compared to conventional blue light Shorter curing time
- 41. 514 nmhas its peak absorption in tissues containing Hb, Hemosiderin and Melanin Has excellent hemostatic capabilities Small diameter flexible glass fiber is used for delivery Used in contact mode Used in Surgical Endodontics Acute inflammatory Periodontal conditions and highly vascularized lesions such as Hemangioma
- 42. Neither wavelengthis absorbed by dental tissues or water Their poor absorption by enamel and dentin is an advantage when used for incising and sculpting gingival tissues Minimal interaction and no damage to tooth surface Both can be used for caries detection Argon laser light illuminates the tooth, the disease area appears dark orange-red colored
- 43. Diode Is asolid active medium laser Manufactured from semiconductor crystals using combinations of Al, In, Ga and Ar Available wavelengths are 800 nm (Al) to 980 nm (In), placing them at the beginning of the infra red spectrum Fiber optic delivered Continuous wave or Gated Pulse modes Used in Contact mode
- 44. Diode WLare highly absorbed by pigmented tissue and deeply penetrating, though hemostasis is not as rapid as with Argon laser Poorly absorbed by tooth tissues Soft tissue surgeries can be performed near tooth Causes a rapid increase in temperature thus, surgical site needs to be air or water cooled Diode is an excellent soft tissue surgical laser Small size & Portable
- 45. Diagnodent (Kavo)is a visible red diode with a WL of 655 nm and 1 milliwatt power This red energy excites fluorescence from carious tooth structure, which is reflected back into a detector device in the unit This analyses and quantifies the degree of caries
- 47. Neodynium:YAG (Nd:YAG) Hasa solid state active medium, which is a garnet crystal combined with rare earth elements Yytrium & Aluminum doped with Neodynium Wavelength is 1064 nm Operate in free running pulsed mode with short pulse durations Delivered via fiber optic cable Contact mode
- 48. Laser lightis highly absorbed by melanin Clinical applications include cutting and coagulating soft tissues Energy is slightly absorbed by dental hard tissues but there is little interaction between sound tooth structure following soft tissue surgery Pigmented surface carious lesions can be vaporized without removing the healthy surrounding enamel
- 49. Holmium:YAG Consists ofa solid crystal of Yytrium, Aluminum Garnet sensitized with Chromium and doped with Holmium and Thulium ions Delivered via Fiber optic cable Free running pulsed mode Wavelength is 2100 nm Absorbed by water 1000 times more than Nd:YAG
- 50. Using peakpowers it can ablate hard calcified tissues As a soft tissue laser instrument it does not react with Hb or other tissue pigments Used more in TMJ disorders and Orthopedic cases
- 51. The Erbium Family 2 distinct lasers Erbium Chromium: YSGG Erbium:YAG
- 52. Er Cr:YSGG ErbiumChromium:Yytrium Scandium Gallium Garnet Wavelength – 2780 nm Delivered via fiber optics Free running pulsed mode Fiber cable diameter is much larger and requires an air or water coolant
- 53. Er:YAG Erbium: Yytrium,Aluminum Garnet Wavelength is 2940 nm Delivered via hollow tube and fiber optic cable Free running pulsed mode
- 54. These 2WL’s have the highest absorption in water and have high affinity for hydroxyapatite The laser couples into hydroxyl radical in the apatite crystal and into water that is bound to the crystalline structures of tooth Caries removal and tooth preparation can be easily carried out The increased water content in carious lesions allows the laser to preferentially interact with diseased tissue
- 55. This isthe most efficient laser for drilling and cutting enamel as its energy is well absorbed by hydroxyapatite
- 56. CO2 Gas activemedium laser Co2 pumped via electrical discharge current and is present in a sealed tube Wavelength is 10,600 nm Delivered via hollow tube or wave guide Continuous or Gated pulsed mode
- 57. Well absorbedby all biological hard & soft tissues Can easily cut and coagulate soft tissue Has a shallow depth of penetration into tissue The laser energy is delivered by a hollow wave guide in a non contact fashion This WL has the highest absorption in hydroxyapatite of any dental laser Thus tooth must be protected during soft tissue application
- 58. Its highthermal absorption makes the CO2 laser less suitable for cutting and drilling enamel & dentin as the damage to the dental pulp may occur
- 59. Lasers in Endodontics DentinalHypersensitivity Pulp Diagnosis Pulp Capping & Pulpotomy Cleaning & Shaping of root canal systems Sterilization Endodontic Surgery
- 60. Dental Hypersensitivity Characterizedas short, sharp pain from exposed dentin that occurs in response to provoking stimuli such as cold, heat or chemicals Not ascribed to any other dental defect or pathology Can be attributed to non carious tooth loss (Wasting diseases)
- 61. Various treatmentmodalities Blocking the dentinal fluid flow Application of various agents to exposed dentinal tubule Oxalate salts Isobutyl cyanoacrylate Fluoride releasing resins Reduce Neuronal Responsiveness 5% Potassium Nitrate & 10% Strontium Nitrate
- 62. Laser as atreatment modality Rationale for laser induced reduction in DH is based on 2 possible mechanisms 1st mechanism – implies direct effect of laser irradiation on the electric activity of nerve fibers within the dental pulp 2nd mechanism – modification of the tubular structure of dentin by melting and fusing of the hard tissue or smear layer and subsequent sealing of dentinal tubules
- 63. Lasers for treatmentof DH are divided into 2 groups: Low Output Power Lasers Middle Output Power Lasers Helium – Neon Diode Nd:YAG Gallium-Aluminum-Arsenide diode Co2
- 64. Pulp Diagnosis LaserDoppler flowmetry (LDF) was developed to assess blood flow in microvascular systems, e.g. in the retina, gut mesentery, renal cortex and skin (Morikawa et al. 1971, Riva et al. 1972)
- 65. Helium –Neon and Diode laser at a low power of 1 or 2 mW Wavelength is 632.8 nm Laser beam is directed towards the tooth (to the blood vessels) Moving RBC causes the frequency of the laser beam to be Doppler shifted and some of the light be back scattered out of the tooth
- 66. The reflectedlight is detected by the photocell on the tooth surface and its output proportional to the number and velocity of the blood cells Advantages : Can be used in traumatized teeth Does not rely on painful sensation to determine vitality
- 68. Pulp Capping &Pulpotomy Pulp capping is a procedure in which a dental material such as Calcium hydroxide or MTA is placed over a pulpal wound to encourage the formation of reparative dentin Pulpotomy is defined as the surgical removal of the coronal portion of the pulp by means of preserving the remaining radicular tissues
- 69. Melcer etal used Co2 lasers & demonstrated new mineralized dentin formation without cellular modifications in pulpal tissues Shoji et al used Co2 lasers in different WL and reported that no damage was detected in the radicular pulp. Charring, coagulation necrosis and degeneration of odontoblastic layer occurred, with no pulp damage Jukic et al used Co2 and Nd:YAG lasers on exposed pulp tissue and reported that a dentinal bridge was formed
- 70. Co2 andNd:YAG lasers are well absorbed by the hydroxyapatite of enamel and dentin, causing tissue ablation, melting and re-solidification These lasers do not cause any thermal damage to the pulp tissue and do not increase the intra-pulpal temperature – if used at the correct power, duration of time and intensity
- 71. Cleaning & Shapingof Root Canal System Various laser systems can deliver the energy into the root canal using a thin optical fiber Various systems that have been used are Nd:YAG Er,Cr:YSGG Argon Diode Er:YAG
- 72. It hasbeen demonstrated in many studies that the laser radiation has the ability to remove debris and smear layer from the root canals It also has the potential to kill the microorganisms Bergman et al suggested that lasers is not an alternative to the conventional cleaning & shaping, but can be used as an adjunct
- 73. Limitations for usein Root Canals Emission of laser energy from the tip of optical fiber or the laser when directed into the root canal is not uniform There may be thermal damage to the periapical tissues May be hazardous when the tooth apex is near vital structures such as mandibular nerve or mental foramen
- 75. Laser assisted Obturation Aim of Obturation: Eliminate all avenues of leakage Seal the RC system from all ends Rationale in using lasers for obturation is that the irradiation can be used as a heat source for softening the GP Conditioning of the dentin walls can also be done
- 76. Lasers in EndodonticSurgery Weichman & Johnson attempted to seal the apical foramen of freshly extracted teeth in which the pulp had been removed Laser is used for the surgery, a bloodless surgical field should be easier to achieve due to the ability of the laser to vaporize tissue and coagulate and seal small blood vessels
- 77. The useof this laser seals the dentinal tubules in the apical portion of the root and sterilizes the surgical site On, extracted teeth (Stabholz et al. 1992 Arens et al. 1993, Wong et al. 1994), used the Nd:YAG laser and found that there was a reduction in the penetration of dye or bacteria within resected roots When the laser was used for resection itself, either in extracted human teeth in vitro (Maillet et al. 1996), found that tissue repairs was quicker when compared with those roots resected with a bur
- 78. Advantages Good hemostasis Improved visualization of surgical site Sterilization operative field Reduced permeability of root surface dentin Reduction in post operative pain Reduced risk of contamination of surgical site by eliminating use of air turbines
- 79. Constraints Time Consuming Increase temperature Causeirreversible pulpal damage Needs precise execution Increased cost of treatment
- 80. Lasers in Operative& Aesthetic Dentistry Lasers have become a part of routine operative and aesthetic practice There are five lasers that are currently in the armamentarium
- 81. Argon lasers Thewavelength is absorbed by Hb This attribute allows precision cutting, hemostasis & coagulation of vascular tissue Use of argon lasers have been used for curing composites (at low power achieving higher bond strength) Transillumination in diagnosis of tooth fractuures
- 82. Plasma Arc Curing(PAC) PAC & Argon laser curing systems have rapid polymerization of composites However they increase heat generation and polymerization shrinkage stresses Studies have shown that they exhibit a narrow spectral output and do not coincide with the spectral requirements of all restorative resins Bleaching of stained teeth
- 83. Co2 Lasers Used forvaporizing, cutting and coagulation of soft tissue Used more for soft tissue procedures which include gingival re-modelling and shaping in aesthetic dentistry (Perio- Aesthetics)
- 84. Diode Lasers 2different WL are used Ga-Al-As Laser (800 nm) & In-Ga- As (980 nm) These are used in contact mode for cavity preparation, removal of bacterial contamination and coagulation of tissue Also used for Diagnosis
- 85. Erbium Family Erlasers are absorbed by Hydroxyapatite and water Allows to cut soft tissue, tooth structure and bone Er:YAG (2940 nm) cuts teeth easily & quickly Also used for removal of caries (excavation)
- 86. Decay present onthe facial of the maxillary left lateral incisor The Erbium laser used to remove the decay. No anesthesia was required After caries removal and preparation is complete Definitive direct bonded restoration after preparation with the Erbium laser
- 87. Etching Laser etchinghas been evaluated as an alternative to acid etching of enamel and dentine. The Er:YAG laser produces micro- explosions during hard tissue ablation that result in microscopic and macroscopic irregularities These micro irregularities make the enamel surface micro retentive and may offer a mechanism of adhesion without acid-etching
- 88. However, ithas been shown that adhesion to dental hard tissues after Er: YAG laser etching is inferior to that obtained after conventional acid etching (Martinez-Insua et al., 2000) The weaker bond strength of the composite to laser-etched enamel and dentine to the presence of subsurface fissuring after laser radiation. This fissuring is not seen in conventional etched surfaces The subsurface fissuring contributed to the high prevalence of cohesive tooth fractures in bonding of both laser-etched enamel and dentine
- 89. Caries prevention Studiesexamined the possibility of using laser to prevent caries (Hossain et al., 2000; Apel et al., 2003) It is believed that laser irradiation of dental hard tissues modifies the calcium to phosphate ratio, reduces the carbonate to phosphorous ratio, and leads to the formation of more stable and less acid soluble compounds, reducing susceptibility to acid attack and caries
- 90. Laboratory studieshave indicated that enamel surfaces exposed to laser irradiation are more acid resistant than non-laser treated surfaces (Watanabe et al., 2001; Arimoto et al., 2001) The degree of protection against caries progression provided by the one-time initial laser treatment was reported to be comparable to daily fluoride treatment by a fluoride dentifrice (Featherstone, 2000)
- 91. Laser Assisted Bleaching Two laser-assisted whitening systems have been cleared by the FDA The laser is used to enhance the activation of bleaching material, which then whitens the teeth The argon laser wavelength of 488 nm for 30 seconds to accelerate the activity of the bleaching gel After the laser energy is applied, the gel is left in place for three minutes, then removed. This procedure is repeated four to six times
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- 95. Laser-assisted toothbleaching, however, still poses a number of unanswered questions Because of continuing concerns and unknowns about laser interactions with hard tissue and the lack of controlled clinical studies, CO2 laser-assisted bleaching is not recommended (FDA) Based on previously accepted uses of argon lasers and associated temperature-rise studies, the use of the argon laser in place of a conventional curing light may be acceptable if the manufacturer’s suggested procedures are carefully followed (FDA)
- 96. Laser Applications Frenectomy •Gingival troughing
- 97. Laser Applications GingivalRecontouring • Gingivoplasty
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- 99. Dental Laser Safety Safety is an integral part of providing dental treatment with lasers 3 aspects to safety: Manufacturing process Proper operation of the device Personal protection
- 100. Regulatory Agencies AmericanNational Standard Institute (ANSI) Food and Drug Administration (FDA) Center for devices and Radiological Health (CDRH) Occupational safety health administration (OSHA)
- 101. Safety Laser Classification ClassLaser Properties I Pose no health hazard e.g. CD Player II Emit only visible light with low power output & do not pose any health hazards Maximum allowable output is 1 mW IIIa Emit any WL and have an output power of 0.5 W of visible light; In this laser light can be viewed only momentarily Caution label is present IIIb Hazardous to unprotected eye; Output power no greater than 0.5 W; eg. Argon Laser curing light; Eye protection is must IV Hazardous from direct viewing and may produce diffuse reflections; Output power more than 0.5 W; Can produce fire and severe skin reactions; Can ignite inflammable devices
- 102. Fire & ExplosionHazards Use only wet and fire retardant materials in operative field Use non combustible anesthetics Avoid alcohol based topical anesthetics Avoid alcohol moistened gauze or cotton Fire Extinguisher Stay informed Follow ANSI regulations
- 103. Laser Safty: Safety Precautions. OcularHazard. Skin Hazard.
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- 108. Guidelines Mention outside Door Switch Fire hazards
- 109. Eye Protection In1962, the awareness to eye protection began Eye is a critical target for laser injury Class III & IV lasers pose a threat to the eye Proper eye wear is a must
- 110. Why the Eye??? Cornea is made up of 90% Water Absorbs emissions from all lasers Cause Corneal Burns Holium and Erbium lasers affect the Aqueous and Vitreous Humor as well as the lens which lead to Aqueous Flare & Cataract formation Retinal damage occurs due to lasers with more depth of penetration and is absorbed into the pigments (Argon, Diode, He:Ne)
- 111. The eyeis 100,000 times more vulnerable to injury than the skin WL from 400-1400 Protective glasses must have an Optical Density of at least 4 For specific high WL lasers like Nd:YAG & Diodes, there are specific eye wear Eyewear is designed to have adequate protection for a wide range of WL’s Regardless of protection, NEVER look directly into the laser beam
- 112. Sterilization & Infection Control Fiber optic cables & handpieces can be autoclaved in pouches Oil based aerosols must not be used The wires and protective casing / housing should be wiped clean and not autoclaved
- 113. The advantages oflaser in dentistry: • Compared to the traditional dental drill, lasers: May cause less pain in some instances, therefore, reducing the need for anesthesia May reduce anxiety in patients uncomfortable with the use of the dental drill Minimize bleeding and swelling during
- 114. The disadvantages oflasers in dentistry: Lasers can't be used on teeth with fillings already in place. Lasers can't be used in many commonly performed dental procedures. For example, lasers can't be used to fill cavities located between teeth, around old fillings, and large cavities that need to be prepared for a crown. In addition, lasers cannot be used to remove defective crowns or silver fillings, or prepare teeth for bridges. Traditional drills may still be needed to shape the filling, adjust the bite, and polish the filling even when a laser is used.
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- 116. There are thousandsof research studies and medical publications,saying that LASER is a very effective modality of treatment that is being widely used all over the world with promising and successful results, also in Orthopedic surgery which is very targety oriented, convenient and cost effective. LASER has been widely used in medical science with proved & promising success for treatment of a variety of medical conditions including carpal tunnel syndrome, cervical neck pain, low back pain, joint pain, frozen shoulder, generalized muscle pain. and acceleration of wound healing. Besides orthopedic application, NASA are currently using Laser for medical conditions in space applications. All of these events validate the growing acceptance in mainstream medicine for the medical efficacy of laser therapy as a viable, often superior therapeutic treatment modality.
- 117. Worldwide laser salesby application ( Ref: Journal of Laser Application, Feb 2005
- 118. General Laser FA Q Q: Is the radiation from lasers harmful? A: The radiation from lasers is light, a form of electro magnetic radiation, which is non-ionizing radiation and is around us all the time. It can be dangerous under certain circumstances such as when a laser beam is projected into the eye, onto the skin or onto flammable materials (see Basic Laser Safety). Ionizing radiation such as that from X-rays, and nuclear materials is dangerous as it can cause cell damage and cancer. If treated with caution and respect, a laser is not dangerous.
- 119. Q: Who inventedthe laser? A: The actual inventor of the laser is lost in a storm of controversy, claims and counter claims. Most historians will agree that the first recorded operation of a laser was on 7th July 1960 by Dr. Theodore Maiman at the Hughes Research Labs in Malibu California. Dr. Maiman’s laser was based on the theoretical ideas of Albert Einstein, Dr. Charles Townes and Arthur Shawlow.
- 120. Q: What isthe star/sun shaped symbol I see all over the web site? A: The symbol is a stylized or simplified version of the international “sunburst” symbol which stands for lasers. The standard international symbol is shown on the left in the International "Lasers In Use" warning sign which should be posted in areas where unshielded lasers are in use. You may even find a similar sign or logo inside your CD player or CD-ROM drive as they use low power laser diodes to read the data from the disk.
- 121. Q: How canlasers hurt me? A: If a high power laser beam strikes you in the eye it can cause a burn on your retina. Just as you can use a magnifying glass to focus the sun and burn with the light, the lens in the human eye focuses the laser beam down to a very small point on the retina which can cause a burn. The focusing effect can concentrate a laser beam up to 100,000 times thus a one watt beam entering the eye can be focused to a point with 100,000 watts of power, more than enough to cause a severe retinal burn and loss of vision
- 122. Q: Are laserspowerful enough to use as weapons like we see in the Star Wars movies and on Star Trek? A: Fortunately present day laser systems are unsuitable for use as weapons as the power needed to cut through space ships or do serious damage to metal objects is extremely high. Presently lasers that are powerful enough to machine metal are large and heavy and require lots of power and cooling water to operate thus are not useful as portable “death rays”.
- 123. Q: How islaser power measured? A: Laser power is measured in watts - the same watts used to measure the power of light bulbs. A 10 watt laser will appear much brighter than a 10 watt light bulb since the light from the bulb travels in all directions and spreads rapidly, while the light from the laser is concentrated in a beam only a few millimeters in diameter.
- 124. Q: Can Ibuild my own laser? A: To build your own laser, you would have to have access to a precision machine shop to build the frame, have glassblowing skills to make the tube, vacuum equipment to pump down the tube and access to rare gasses to fill the tube; you would also need considerable electronics skills to build the exciter (power supply). It would be like trying to build your own light bulb or fluorescent tube. It is simpler to purchase a laser as low cost HeNe and diode lasers are readily available. Q: I still want to try building a laser... is there any place I can get plans? A: You can visit the Laser Hobbyists topic in our Backstage Area which has a Laser Construction page with some information that may be helpful. Be leery of those who offer low cost plans for building a laser on the net as these plans are often useless.
- 125. Q: Do allLasers need to have a cooling system? A: Small lasers such as HeNe and diode lasers usually do not need any special cooling systems as they cool by convection of the air around them, or by conduction of the heat into the mounting or casing. As the output power of the laser increases, the amount of heat produced increases and cooling systems have to be used. CW lasers up to about one watt can be air- cooled, over 1 watt most lasers require water cooling as air can not remove the heat fast enough, although there are Copper Vapor and YAG lasers that produce several watts of optical power and are air-cooled.
- 126. References Pathways ofPulp (9th Ed.) – S.Cohen Art & Science of Operative Dentistry – Sturdevant Textbook of Endodontics (6th Ed.)– Ingle DCNA – 2000, 2005 Journal of Endodontics International Endodontic Journal Journal of American Dental Association British Dental Journal