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