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BIOMEDICAL OPTICSAND LASERS
By:
Engr. Joseph Ronald Cañedo
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Outline
• Introduction / literature
• Basics of laser physics
• Matter acting on light
• Light acting on matter
• Medical laser applications
• Laser safety
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Electromagnetic spectrum
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LASER: Light Amplified by Stimulated Emission of Radiation
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Laser beam characteristics
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Matter acting on light
• reflection and refraction• absorption and scattering
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Reflection and refraction
law of reflection: θ = θ‘law of refraction: n1 sin θ = n2 sin θ‘‘
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Absorption• tissue absorption according to Lambert-Beer:
I(z) = I0 exp (−αz)
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Light acting on matter
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Laser-tissue interactions
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Photochemical interaction
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Thermal interaction
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Extra: Laser-induced interstitial thermotherapy (LITT)
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Plasma-induced ablation
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Photodisruption• pulse duration: 10−15 − 10− 9 sec• energy density: 1 − 1000 J/cm2• power density: 1011 − 1013 W/cm2• electric field strength: 107 − 108 V/cm
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Laser applications in medicine
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Laser applications in ophthalmology
• Indications:– retinal detachment– Cataract– Glaucoma– wrong-sightedness
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Wrong-sightedness
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Refractive power of the eye
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Techniques in refractive corneal surgery
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Model of keratomileusis
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fs-LASIK: Laser in situ keratomileusis with the femtosecond laser
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Laser applications in dentistry
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Pain free caries therapy: Investigated laser systems
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Caries diagnostics by plasma spectroscopy
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Plasma spectroscopy
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Laser applications in neurosurgery
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Laser safety classes
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Realized laser safety• laser safety officer• laser safety equipment:
1. warning sign and warning lamp2. safety curtain3. safety glasses